Subarachnoid Hemorrhage (Clinical)

Definition and Epidemiology

Definition^[2]

• SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage is a type of cerebrovascular accident Cerebrovascular accident An ischemic stroke (also known as cerebrovascular accident) is an acute neurologic injury that occurs as a result of brain ischemia; this condition may be due to cerebral blood vessel occlusion by thrombosis or embolism, or rarely due to systemic hypoperfusion. Ischemic Stroke (stroke) resulting from intracranial hemorrhage Intracranial hemorrhage Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most sahs originate from a saccular aneurysm in the circle of willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage into the subarachnoid space Subarachnoid space The space between the arachnoid membrane and pia mater, filled with cerebrospinal fluid. It contains large blood vessels that supply the brain and spinal cord. Subarachnoid Hemorrhage. 
• Subarachnoid space Subarachnoid space The space between the arachnoid membrane and pia mater, filled with cerebrospinal fluid. It contains large blood vessels that supply the brain and spinal cord. Subarachnoid Hemorrhage: area between the arachnoid mater Arachnoid mater A delicate membrane enveloping the brain and spinal cord. It lies between the pia mater and the dura mater. It is separated from the pia mater by the subarachnoid cavity which is filled with cerebrospinal fluid. Meninges: Anatomy and the pia mater Pia mater The innermost layer of the three meninges covering the brain and spinal cord. It is the fine vascular membrane that lies under the arachnoid and the dura mater. Meninges: Anatomy layers of the meninges Meninges The brain and the spinal cord are enveloped by 3 overlapping layers of connective tissue called the meninges. The layers are, from the most external layer to the most internal layer, the dura mater, arachnoid mater, and pia mater. Between these layers are 3 potential spaces called the epidural, subdural, and subarachnoid spaces. Meninges: Anatomy surrounding the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification

Epidemiology^[2]

• Hemorrhagic strokes:
  • Account for 15%–20% of cerebrovascular accidents 
  • 50% of hemorrhagic strokes are due to SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage.
• Saccular aneurysms Saccular aneurysms Brain Aneurysms:^[7]
  • Ruptured saccular aneurysms Saccular aneurysms Brain Aneurysms are the most common cause of SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage.
  • Approximately 3%–5% of the population has radiographic evidence of unruptured saccular aneurysm Saccular Aneurysm Subarachnoid Hemorrhage.
  • Most aneurysms, especially small ones, do not rupture.
• 15%–20% percent of SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage cases are non-aneurysmal.
• Incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency:
  • Global incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency of SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage: 6–10 cases/100,000 person-years
  • Blacks > whites
  • Women > men (slightly)
• Manifests most commonly at 40–60 years of age

Etiology

Risk factors^[2,7,8]

• Genetics Genetics Genetics is the study of genes and their functions and behaviors. Basic Terms of Genetics, increased incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency seen in:
  • Autosomal dominant polycystic kidney disease Autosomal dominant polycystic kidney disease Polycystic kidney disease (PKD) is an inherited genetic disorder leading to the development of numerous fluid-filled cysts in the kidneys. The 2 main types of PKD are autosomal dominant polycystic kidney disease (ADPKD), which is often diagnosed in adulthood, and autosomal recessive polycystic kidney disease (ARPKD), which is often diagnosed antenatally or shortly after birth. Autosomal dominant polycystic kidney disease (ADPKD) ( ADPKD ADPKD Polycystic kidney disease (PKD) is an inherited genetic disorder leading to the development of numerous fluid-filled cysts in the kidneys. The 2 main types of PKD are autosomal dominant polycystic kidney disease (ADPKD), which is often diagnosed in adulthood, and autosomal recessive polycystic kidney disease (ARPKD), which is often diagnosed antenatally or shortly after birth. Autosomal dominant polycystic kidney disease (ADPKD))
  • Ehlers-Danlos syndrome Ehlers-Danlos syndrome Ehlers-Danlos syndrome (EDS) is a heterogeneous group of inherited connective tissue disorders that are characterized by hyperextensible skin, hypermobile joints, and fragility of the skin and connective tissue. Ehlers-Danlos Syndrome (EDS)
  • Primary aldosteronism (glucocorticoid-remediable aldosteronism (GRA))
• Family history Family History Adult Health Maintenance:
  • Up to fivefold increased risk in 1st-degree relatives
  • Familial cerebral aneurysms rupture more frequently than nonfamilial aneurysms
• Hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension
• Stimulant use:
  • Cocaine Cocaine An alkaloid ester extracted from the leaves of plants including coca. It is a local anesthetic and vasoconstrictor and is clinically used for that purpose, particularly in the eye, ear, nose, and throat. It also has powerful central nervous system effects similar to the amphetamines and is a drug of abuse. Cocaine, like amphetamines, acts by multiple mechanisms on brain catecholaminergic neurons; the mechanism of its reinforcing effects is thought to involve inhibition of dopamine uptake. Local Anesthetics
  • Amphetamine/ methamphetamine Methamphetamine A central nervous system stimulant and sympathomimetic with actions and uses similar to dextroamphetamine. The smokable form is a drug of abuse and is referred to as crank, crystal, crystal meth, ice, and speed. Stimulants
  • Sympathomimetics Sympathomimetics Sympathomimetic drugs, also known as adrenergic agonists, mimic the action of the stimulators (î±, β, or dopamine receptors) of the sympathetic autonomic nervous system. Sympathomimetic drugs are classified based on the type of receptors the drugs act on (some agents act on several receptors but 1 is predominate). Sympathomimetic Drugs:
    • Cold remedies
    • Appetite suppressants
• Coagulopathy:
  • Genetic or acquired bleeding diathesis Bleeding diathesis Wiskott-Aldrich Syndrome
  • Therapeutic or supratherapeutic anticoagulation Anticoagulation Pulmonary Hypertension Drugs
• Cigarette smoking Smoking Willful or deliberate act of inhaling and exhaling smoke from burning substances or agents held by hand. Interstitial Lung Diseases
  • Dose dependent Dose Dependent Drug-Induced Liver Injury
  • Risk decreases after cessation.
• Alcohol use disorder Alcohol use disorder Alcohol is one of the most commonly used addictive substances in the world. Alcohol use disorder (AUD) is defined as pathologic consumption of alcohol leading to impaired daily functioning. Acute alcohol intoxication presents with impairment in speech and motor functions and can be managed in most cases with supportive care. Alcohol Use Disorder
• Estrogen Estrogen Compounds that interact with estrogen receptors in target tissues to bring about the effects similar to those of estradiol. Estrogens stimulate the female reproductive organs, and the development of secondary female sex characteristics. Estrogenic chemicals include natural, synthetic, steroidal, or non-steroidal compounds. Ovaries: Anatomy deficiency (increased incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency observed in women > 50 years of age)
• Increased incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency observed in multiparous Multiparous A woman with prior deliveries Normal and Abnormal Labor females

Causes^[2,7,8]

• Trauma
• Ruptured aneurysms
  • Saccular aneurysms Saccular aneurysms Brain Aneurysms (“ berry aneurysms Berry aneurysms Brain Aneurysms,” round shape) are the most common cause of SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage.
  • Fusiform aneurysms (dilatation of the entire vessel wall for a short distance) and mycotic aneurysms (bacterial, fungal, or viral infection of the vessel wall) are also possible.
• Arteriovenous malformations Arteriovenous malformations Congenital vascular anomalies in the brain characterized by direct communication between an artery and a vein without passing through the capillaries. The locations and size of the shunts determine the symptoms including headaches; seizures; stroke; intracranial hemorrhages; mass effect; and vascular steal effect. Intracerebral Hemorrhage (AVMs)
• Arterial dissections
• Vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus
• Vascular amyloid deposition
• Pituitary apoplexy Pituitary apoplexy The sudden loss of blood supply to the pituitary gland, leading to tissue necrosis and loss of function (panhypopituitarism). The most common cause is hemorrhage or infarction of a pituitary adenoma. It can also result from acute hemorrhage into sella turcica due to head trauma; intracranial hypertension; or other acute effects of central nervous system hemorrhage. Clinical signs include severe headache; hypotension; bilateral visual disturbances; unconsciousness; and coma. Hypopituitarism
• Illicit stimulant use

Pathophysiology

Given that saccular aneurysm Saccular Aneurysm Subarachnoid Hemorrhage is the most common etiology of SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage, this section will focus on the pathogenesis of saccular aneurysm Saccular Aneurysm Subarachnoid Hemorrhage rupture. Events that occur after the rupture itself are common to other etiologies of SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage. 

Saccular aneurysm Saccular Aneurysm Subarachnoid Hemorrhage^[2,7]

• Protrusions from intracranial arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology
  • Thin-walled
  • Tunica media Tunica media The middle layer of blood vessel walls, composed principally of thin, cylindrical, smooth muscle cells and elastic tissue. It accounts for the bulk of the wall of most arteries. The smooth muscle cells are arranged in circular layers around the vessel, and the thickness of the coat varies with the size of the vessel. Arteries: Histology may be absent or thin.
  • Absence of the internal elastic Elastic Connective Tissue: Histology lamina is a common finding.
• Acquired lesions rather than congenital Congenital Chorioretinitis
• Most commonly located in the circle of Willis Circle of Willis A polygonal anastomosis at the base of the brain formed by the internal carotid, proximal parts of the anterior, middle, and posterior cerebral arteries, the anterior communicating artery and the posterior communicating arteries. Subarachnoid Hemorrhage
  • Located in the anterior circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment > posterior circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment
  • Sites of bifurcation are the most vulnerable.
• Develop over a short time in response to abnormal vascular shear forces:
  • Time period thought to be short (hours to days)
  • May rupture or harden after initial dilation
• Not all saccular aneurysms Saccular aneurysms Brain Aneurysms rupture:
  • Stabilization may occur with hardening due to collagen Collagen A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of skin; connective tissue; and the organic substance of bones (bone and bones) and teeth (tooth). Connective Tissue: Histology deposition.
  • Stable saccular aneurysms Saccular aneurysms Brain Aneurysms are relatively common.

Pathologic features of ruptured saccular aneurysms Saccular aneurysms Brain Aneurysms^[2,7]

• Abnormalities in smooth muscle organization
• Hypocellularity
• Intimal hyperplasia Hyperplasia An increase in the number of cells in a tissue or organ without tumor formation. It differs from hypertrophy, which is an increase in bulk without an increase in the number of cells. Cellular Adaptation
• Infiltration with T cells T cells Lymphocytes responsible for cell-mediated immunity. Two types have been identified – cytotoxic (t-lymphocytes, cytotoxic) and helper T-lymphocytes (t-lymphocytes, helper-inducer). They are formed when lymphocytes circulate through the thymus gland and differentiate to thymocytes. When exposed to an antigen, they divide rapidly and produce large numbers of new T cells sensitized to that antigen. T cells: Types and Functions and macrophages Macrophages The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood monocytes. Main types are peritoneal macrophages; alveolar macrophages; histiocytes; kupffer cells of the liver; and osteoclasts. They may further differentiate within chronic inflammatory lesions to epithelioid cells or may fuse to form foreign body giant cells or langhans giant cells. Innate Immunity: Phagocytes and Antigen Presentation
• Thin layer of thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus
• Presence of odontogenic bacterial DNA DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure (possible role of dental/periodontal infection)

Risk factors for rupture^[2,7]

• Aneurysm Aneurysm An aneurysm is a bulging, weakened area of a blood vessel that causes an abnormal widening of its diameter > 1.5 times the size of the native vessel. Aneurysms occur more often in arteries than in veins and are at risk of dissection and rupture, which can be life-threatening. Thoracic Aortic Aneurysms size (diameter) > 7 mm → ↑ risk of aneurysmal rupture Aneurysmal rupture The tearing or bursting of the weakened wall of the aneurysmal sac, usually heralded by sudden worsening pain. The great danger of a ruptured aneurysm is the large amount of blood spilling into the surrounding tissues and cavities, causing hemorrhagic shock. Thoracic Aortic Aneurysms:
  • Larger aneurysms are more likely to grow than smaller aneurysms.
  • The rate of rupture risk is proportional to the diameter of the aneurysm Aneurysm An aneurysm is a bulging, weakened area of a blood vessel that causes an abnormal widening of its diameter > 1.5 times the size of the native vessel. Aneurysms occur more often in arteries than in veins and are at risk of dissection and rupture, which can be life-threatening. Thoracic Aortic Aneurysms.
• Aneurysm Aneurysm An aneurysm is a bulging, weakened area of a blood vessel that causes an abnormal widening of its diameter > 1.5 times the size of the native vessel. Aneurysms occur more often in arteries than in veins and are at risk of dissection and rupture, which can be life-threatening. Thoracic Aortic Aneurysms growth:
  • Aneurysmal growth increases the diameter of the lesion.
  • Rapid growth outpaces the ability for collagen-mediated stabilization.
• Aneurysm Aneurysm An aneurysm is a bulging, weakened area of a blood vessel that causes an abnormal widening of its diameter > 1.5 times the size of the native vessel. Aneurysms occur more often in arteries than in veins and are at risk of dissection and rupture, which can be life-threatening. Thoracic Aortic Aneurysms site:
  • The risk of rupture varies based on the parent vessel giving rise to the aneurysm Aneurysm An aneurysm is a bulging, weakened area of a blood vessel that causes an abnormal widening of its diameter > 1.5 times the size of the native vessel. Aneurysms occur more often in arteries than in veins and are at risk of dissection and rupture, which can be life-threatening. Thoracic Aortic Aneurysms.
  • Posterior circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment > anterior circulation Circulation The movement of the blood as it is pumped through the cardiovascular system. ABCDE Assessment > cavernous carotid artery

Factors that may trigger Trigger The type of signal that initiates the inspiratory phase by the ventilator Invasive Mechanical Ventilation rupture^[2,7]

• Trauma
• Physical exertion within 2 hours of rupture
• Valsalva maneuver Valsalva maneuver Forced expiratory effort against a closed glottis. Rectal Prolapse (prolonged or repetitive)
• Uncontrolled hypertension Uncontrolled hypertension Although hypertension is defined as a blood pressure of > 130/80 mm Hg, individuals can present with comorbidities of severe asymptomatic or “uncontrolled” hypertension (≥ 180 mm Hg systolic and/or ≥ 120 mm Hg diastolic) that carries with it a significant risk of morbidity and mortality. Uncontrolled Hypertension
• Rupture can also occur with nonstrenuous activity.

Clinical sequelae of rupture^[2,7]

• Leakage of blood into the CSF:
  • Leads to increased intracranial pressure Intracranial Pressure Idiopathic Intracranial Hypertension ( ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP))
  • Initial bleeding (sentinel bleed) may last only seconds but with a high incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency of rebleeding.
• Hydrocephalus Hydrocephalus Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, intracranial. Subarachnoid Hemorrhage/ increased ICP Increased ICP Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, intracranial. Subarachnoid Hemorrhage:
  • Blockage of CSF flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure and/or reabsorption caused by buildup of blood products and or/adhesions 
  • Continued leakage of blood into the subarachnoid space Subarachnoid space The space between the arachnoid membrane and pia mater, filled with cerebrospinal fluid. It contains large blood vessels that supply the brain and spinal cord. Subarachnoid Hemorrhage compounds the problem.
  • Endothelial dysfunction from the site of rupture causes local hyperemia and inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation.
• Cerebral vasospasm:
  • Release of inflammatory mediators from injured vessels may cause local vasoconstriction Vasoconstriction The physiological narrowing of blood vessels by contraction of the vascular smooth muscle. Vascular Resistance, Flow, and Mean Arterial Pressure.
  • Vasospasm causes local hypoperfusion, worsening the ischemic insult.

Clinical Presentation

History

The classic presenting symptom of SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage is a thunderclap headache Thunderclap Headache Subarachnoid Hemorrhage. There are other presenting symptoms as well.

• Thunderclap headache Thunderclap Headache Subarachnoid Hemorrhage:^[6,11,15,17]
  • Sudden onset (seconds to minutes)
  • “ Worst headache of my life Worst Headache of My Life Subarachnoid Hemorrhage”
  • Often (10%–40%) preceded by less severe prodromal headaches (“sentinel headaches”)
  • Headache Headache The symptom of pain in the cranial region. It may be an isolated benign occurrence or manifestation of a wide variety of headache disorders. Brain Abscess location/description is inconsistent among SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage sufferers.
  • Headache Headache The symptom of pain in the cranial region. It may be an isolated benign occurrence or manifestation of a wide variety of headache disorders. Brain Abscess presentation: not always severe but usually accompanied by nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics and vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia^[14]
• Neck stiffness Neck Stiffness Meningitis/ pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways:^[6,11,17]
  • Correlates with spread of blood into the CSF causing meningeal irritation Meningeal Irritation Subarachnoid Hemorrhage
  • Often presents hours after the onset of headache Headache The symptom of pain in the cranial region. It may be an isolated benign occurrence or manifestation of a wide variety of headache disorders. Brain Abscess
• Altered level of consciousness Altered Level of Consciousness Intracerebral Hemorrhage^[6,15]:
  • Brief loss of consciousness 
  • Altered mental status Altered Mental Status Sepsis in Children/confusion/ agitation Agitation A feeling of restlessness associated with increased motor activity. This may occur as a manifestation of nervous system drug toxicity or other conditions. St. Louis Encephalitis Virus 
  • Coma Coma Coma is defined as a deep state of unarousable unresponsiveness, characterized by a score of 3 points on the GCS. A comatose state can be caused by a multitude of conditions, making the precise epidemiology and prognosis of coma difficult to determine. Coma is uncommon.
  • Sudden death occurs in > 20% of affected individuals before presenting to medical attention Attention Focusing on certain aspects of current experience to the exclusion of others. It is the act of heeding or taking notice or concentrating. Psychiatric Assessment. 
• Seizure:^[11,17]
  • In approximately 10%–20% of SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage cases
  • Generally occur in the first 24 hours
  • Associated with poor outcome 
  • Seen in association with middle cerebral and anterior communicating artery aneurysms
• Nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics/ vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia^[6,17]
• Sentinel hemorrhage:^[6,17]
  • A “warning leak” occurring prior to major hemorrhage
  • Symptoms (milder headache Headache The symptom of pain in the cranial region. It may be an isolated benign occurrence or manifestation of a wide variety of headache disorders. Brain Abscess, nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics, vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia) take place around 2–8 weeks before the SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage.
  • Neck stiffness Neck Stiffness Meningitis not commonly noted.

Physical examination

• Elevated blood pressure^[6,19]
  • Often in the severe range
  • May be a precipitating event for aneurysmal rupture Aneurysmal rupture The tearing or bursting of the weakened wall of the aneurysmal sac, usually heralded by sudden worsening pain. The great danger of a ruptured aneurysm is the large amount of blood spilling into the surrounding tissues and cavities, causing hemorrhagic shock. Thoracic Aortic Aneurysms
  • May be a reactive phenomenon to intracerebral events
• Meningismus Meningismus Subarachnoid Hemorrhage^[6,17]
  • Correlates with spread of blood into the CSF causing meningeal irritation Meningeal Irritation Subarachnoid Hemorrhage
  • Kernig and Brudzinski signs Brudzinski Signs Meningitis in Children may be present
• Preretinal hemorrhage (Terson syndrome)^[6]
  • Associated with increased ICP Increased ICP Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, intracranial. Subarachnoid Hemorrhage as opposed to true retinal involvement
  • Associated with poor outcome
• Oculomotor nerve Oculomotor nerve The 3D cranial nerve. The oculomotor nerve sends motor fibers to the levator muscles of the eyelid and to the superior rectus, inferior rectus, and inferior oblique muscles of the eye. It also sends parasympathetic efferents (via the ciliary ganglion) to the muscles controlling pupillary constriction and accommodation. The motor fibers originate in the oculomotor nuclei of the midbrain. The 12 Cranial Nerves: Overview and Functions (CN III) palsy Palsy paralysis of an area of the body, thus incapable of voluntary movement Cranial Nerve Palsies^[6]
  • Often presents as a unilateral pupillary defect
  • Due to CN III compression Compression Blunt Chest Trauma from aneurysm Aneurysm An aneurysm is a bulging, weakened area of a blood vessel that causes an abnormal widening of its diameter > 1.5 times the size of the native vessel. Aneurysms occur more often in arteries than in veins and are at risk of dissection and rupture, which can be life-threatening. Thoracic Aortic Aneurysms of the posterior communicating artery or superior cerebellar artery Superior cerebellar artery Cerebrovascular System: Anatomy (located near CN III exit site from the brainstem)
• Focal neurologic deficit Focal Neurologic Deficit Intracerebral Hemorrhage^[11,15]
  • SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage can manifest with a wide variety of neurologic findings.
  • Findings depend on the size and location of the hemorrhage.
• Cushing triad^[19]
  • Due to raised ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP) 
  • Widened pulse pressure (raised systolic, lowered diastolic) 
  • Irregular respirations 
  • Bradycardia Bradycardia Bradyarrhythmia is a rhythm in which the heart rate is less than 60/min. Bradyarrhythmia can be physiologic, without symptoms or hemodynamic change. Pathologic bradyarrhythmia results in reduced cardiac output and hemodynamic instability causing syncope, dizziness, or dyspnea. Bradyarrhythmias

Diagnosis

Any thunderclap headache Thunderclap Headache Subarachnoid Hemorrhage presenting with or without neurologic symptoms/signs or altered mental status Altered Mental Status Sepsis in Children should be emergently evaluated with neuroimaging Neuroimaging Non-invasive methods of visualizing the central nervous system, especially the brain, by various imaging modalities. Febrile Infant. Noncontrast CT is readily available at most acute care hospitals and is the initial test of choice. 

If the person is unstable, rapidly deteriorating, or displaying signs of raised ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP), do not wait for diagnostic confirmation before stabilizing the patient and commencing neuroprotective measures.

Ottawa SAH rule Ottawa SAH rule Subarachnoid Hemorrhage^[15]

• Clinical decision tool used to evaluate suspected SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage with emergent noncontrast CT of the head (Ottawa SAH calculator)
• Evaluated in neurologically intact patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship presenting with thunderclap headache Thunderclap Headache Subarachnoid Hemorrhage
• Sensitivity: 100%, specificity: 15% 
• The presence of any of the following features is an indication for emergent CT:
  • Neck Neck The part of a human or animal body connecting the head to the rest of the body. Peritonsillar Abscess pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways or stiffness
  • Limited neck Neck The part of a human or animal body connecting the head to the rest of the body. Peritonsillar Abscess flexion Flexion Examination of the Upper Limbs on examination
  • Witnessed loss of consciousness
  • Onset during exertion
  • Thunderclap headache Thunderclap Headache Subarachnoid Hemorrhage (instantly peaking pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways)
  • Age ≥ 40 years

Noncontrast head CT^[9,11,17]

• Cornerstone of SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage diagnosis
• Sensitivity of up to 100%:
  • If performed within 6 hours of presentation (sensitivity drops to 86% if performed after 6 hours)^[15]
  • If reviewed by qualified neuroradiologist
• Should include cuts through the base of the brain Brain The part of central nervous system that is contained within the skull (cranium). Arising from the neural tube, the embryonic brain is comprised of three major parts including prosencephalon (the forebrain); mesencephalon (the midbrain); and rhombencephalon (the hindbrain). The developed brain consists of cerebrum; cerebellum; and other structures in the brain stem. Nervous System: Anatomy, Structure, and Classification
• Locations of blood in SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage:
  • Basal cistern(s): most common
  • Sylvian fissure Fissure A crack or split that extends into the dermis Generalized and Localized Rashes(s)
  • Interhemispheric fissure Fissure A crack or split that extends into the dermis Generalized and Localized Rashes
  • Interpeduncular fossa

Lumbar puncture Lumbar Puncture Febrile Infant (LP)

An LP should be performed promptly (despite negative CT if clinical suspicion of SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage is high).^[10,12,15]

• Whenever possible, the sample should be collected at least 12 hours after the event. 
• The sample should be protected from light (wrapped in foil or placed in a thick brown envelope Envelope Bilayer lipid membrane acquired by viral particles during viral morphogenesis. Although the lipids of the viral envelope are host derived, various virus-encoded integral membrane proteins, i.e. Viral envelope proteins are incorporated there. Virology outside the specimen back) to prevent degradation of bilirubin Bilirubin A bile pigment that is a degradation product of heme. Heme Metabolism. 
• Avoid vacuum tube transport systems.

Studies should include:^[12,15]

• Opening pressure
• Cell counts:
  • RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology
  • WBCs
  • Visual inspection Inspection Dermatologic Examination for xanthochromia Xanthochromia Subarachnoid Hemorrhage ( yellowish appearance Yellowish Appearance Subarachnoid Hemorrhage due to presence of bilirubin Bilirubin A bile pigment that is a degradation product of heme. Heme Metabolism)
    • RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology release oxyhemoglobin as they break down.
    • Oxyhemoglobin converts to methemoglobin then to bilirubin Bilirubin A bile pigment that is a degradation product of heme. Heme Metabolism (in vivo) → xanthochromia Xanthochromia Subarachnoid Hemorrhage
    • Xanthochromia Xanthochromia Subarachnoid Hemorrhage indicates that blood has been in the CSF for ≥ 2 hours.
• Classic LP findings:
  • Elevated opening pressure
  • Elevated RBC count followed by xanthochromia Xanthochromia Subarachnoid Hemorrhage
• SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage is ruled out when:^[15,20]
  • RBC  < 2000 × 10⁶/L
  • No xanthochromia Xanthochromia Subarachnoid Hemorrhage seen
• False-positive LP findings:
  • A ”traumatic tap” may reveal a falsely elevated RBC count.
  • Differential of RBC counts between successive sample tubes can help differentiate false positives from true positives.
  • The RBC count should decrease or clear with successive tubes.

Identification Identification Defense Mechanisms of the bleeding source^{[9,11,17,22,25]}

• After SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage is established, angiographic studies should be performed to identify the hemorrhagic source:
  • Digital subtraction angiography Angiography Radiography of blood vessels after injection of a contrast medium. Cardiac Surgery (DSA): preferred method, allows for intervention to be performed simultaneously with identification Identification Defense Mechanisms of the source
  • CTA CTA A non-invasive method that uses a ct scanner for capturing images of blood vessels and tissues. A contrast material is injected, which helps produce detailed images that aid in diagnosing vascular diseases. Pulmonary Function Tests and MRA MRA Imaging of the Heart and Great Vessels: noninvasive alternatives
• Once the bleeding source is identified, clinical decisions about appropriateness of intervention are undertaken.

Severity assessment^[14,15,21]

Several scales Scales Dry or greasy masses of keratin that represent thickened stratum corneum. Secondary Skin Lesions are utilized clinically in the diagnosis and grading Grading Methods which attempt to express in replicable terms the level of cell differentiation in neoplasms as increasing anaplasia correlates with the aggressiveness of the neoplasm. Grading, Staging, and Metastasis of severity in SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage. The Hunt and Hess grading Grading Methods which attempt to express in replicable terms the level of cell differentiation in neoplasms as increasing anaplasia correlates with the aggressiveness of the neoplasm. Grading, Staging, and Metastasis system (calculator) is among the most commonly used in clinical medicine. Another system is the World Federation of Neurological Surgeons grading Grading Methods which attempt to express in replicable terms the level of cell differentiation in neoplasms as increasing anaplasia correlates with the aggressiveness of the neoplasm. Grading, Staging, and Metastasis scale Scale Dermatologic Examination, which incorporates the Glasgow Coma Coma Coma is defined as a deep state of unarousable unresponsiveness, characterized by a score of 3 points on the GCS. A comatose state can be caused by a multitude of conditions, making the precise epidemiology and prognosis of coma difficult to determine. Coma Scale Scale Dermatologic Examination ( GCS GCS A scale that assesses the response to stimuli in patients with craniocerebral injuries. The parameters are eye opening, motor response, and verbal response. Coma) with motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology deficits.

• Other grading Grading Methods which attempt to express in replicable terms the level of cell differentiation in neoplasms as increasing anaplasia correlates with the aggressiveness of the neoplasm. Grading, Staging, and Metastasis systems are available.
• The above scales Scales Dry or greasy masses of keratin that represent thickened stratum corneum. Secondary Skin Lesions, which are commonly used, have notable intraobserver and interobserver variability.
• No single scale Scale Dermatologic Examination has been found to be optimal in determining prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas and in helping to guide management.
• Choice of system depends on the individual and/or institution; it is important, however, to consider other important factors that determine prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas, including:
  • Age
  • Hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension
  • Size of bleed on CT scan
  • Aneurysm Aneurysm An aneurysm is a bulging, weakened area of a blood vessel that causes an abnormal widening of its diameter > 1.5 times the size of the native vessel. Aneurysms occur more often in arteries than in veins and are at risk of dissection and rupture, which can be life-threatening. Thoracic Aortic Aneurysms location and size
  • Other cranial areas affected by hemorrhage
  • Time of admission

Routine laboratory studies^[25]

Additional tests that may help guide diagnosis and management include:

• CBC
• Coagulation studies Coagulation studies Coagulation studies are a group of hematologic laboratory studies that reflect the function of blood vessels, platelets, and coagulation factors, which all interact with one another to achieve hemostasis. Coagulation studies are usually ordered to evaluate patients with bleeding or hypercoagulation disorders. Coagulation Studies (PTT, PT/INR)
• Creatinine
• Glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance
• Troponin
• Toxicology screening Screening Preoperative Care
• Inflammatory markers
• ECG ECG An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures. Electrocardiogram (ECG)

Complications

The following are potential complications of SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage:^[17,18,22]

• Rebleeding:
  • Occurs in ⅓ of SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage cases 
  • Maximum risk within 1st 2–12 hours
  • Associated with poor outcomes 
  • Factors that increase rebleeding:
    • Longer wait until aneurysm Aneurysm An aneurysm is a bulging, weakened area of a blood vessel that causes an abnormal widening of its diameter > 1.5 times the size of the native vessel. Aneurysms occur more often in arteries than in veins and are at risk of dissection and rupture, which can be life-threatening. Thoracic Aortic Aneurysms treatment
    • Loss of consciousness on initial presentation
    • Sentinel headache Headache The symptom of pain in the cranial region. It may be an isolated benign occurrence or manifestation of a wide variety of headache disorders. Brain Abscess
    • Large aneurysm Aneurysm An aneurysm is a bulging, weakened area of a blood vessel that causes an abnormal widening of its diameter > 1.5 times the size of the native vessel. Aneurysms occur more often in arteries than in veins and are at risk of dissection and rupture, which can be life-threatening. Thoracic Aortic Aneurysms size
    • High systolic blood pressure
    • Acute hydrocephalus Hydrocephalus Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, intracranial. Subarachnoid Hemorrhage
• Vasospasm leading to delayed cerebral ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage:
  • Most frequent 7–10 days after initial event 
  • Can lead to ischemic stroke Ischemic Stroke An ischemic stroke (also known as cerebrovascular accident) is an acute neurologic injury that occurs as a result of brain ischemia; this condition may be due to cerebral blood vessel occlusion by thrombosis or embolism, or rarely due to systemic hypoperfusion. Ischemic Stroke 
• Hydrocephalus Hydrocephalus Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, intracranial. Subarachnoid Hemorrhage:
  • Can be seen within hours of SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage or a later complication (chronic)
  • Occurs from obstruction of blood products and/or reduced absorption Absorption Absorption involves the uptake of nutrient molecules and their transfer from the lumen of the GI tract across the enterocytes and into the interstitial space, where they can be taken up in the venous or lymphatic circulation. Digestion and Absorption of CSF
• Hyponatremia Hyponatremia Hyponatremia is defined as a decreased serum sodium (sNa+) concentration less than 135 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled via antidiuretic hormone (ADH) release from the hypothalamus and by the thirst mechanism. Hyponatremia: may be due to cerebral salt wasting or SIADH SIADH Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a disorder of impaired water excretion due to the inability to suppress the secretion of antidiuretic hormone (ADH). SIADH is characterized by impaired water excretion leading to dilutional hyponatremia, which is mainly asymptomatic but may cause neurologic symptoms. S Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)
• Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever: most common medical complication  
• Seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures 
• Anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types
• Cardiopulmonary events

Management

Management may vary depending on practice location. The following information is based on US and UK literature and guidelines. Treatment may be guided by specialist consultation (e.g., neurosurgery Neurosurgery Neurosurgery is a specialized field focused on the surgical management of pathologies of the brain, spine, spinal cord, and peripheral nerves. General neurosurgery includes cases of trauma and emergencies. There are a number of specialized neurosurgical practices, including oncologic neurosurgery, spinal neurosurgery, and pediatric neurosurgery. Neurosurgery).

Stabilize life-threatening conditions^[15,22,25]

• ABCDE management:
  • Intubation Intubation Peritonsillar Abscess, particularly in the following cases:
    • Comatose state Comatose State Coma
    • Hemodynamically instability
    • Heavy sedation 
    • Paralysis
    • Hypoxemia Hypoxemia Neonatal Respiratory Distress Syndrome
    • Hypoventilation
    • Elevated ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP)
  • Address any trauma-related conditions:
    • Administer blood products in blood loss anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types
    • Address internal organ damage
  • Stabilize cardiovascular status:
    • Check cardiac troponins on admission 
    • Address arrhythmia
    • Stabilize blood pressure
  • Maintain euvolemia Euvolemia Volume Depletion and Dehydration 
  • Treat seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures (see below for details)
• Keep on nothing-by-mouth status in anticipation Anticipation The apparent tendency of certain diseases to appear at earlier age of onset and with increasing severity in successive generations. Huntington Disease of possible surgery 
• Discontinue/reverse anticoagulants Anticoagulants Anticoagulants are drugs that retard or interrupt the coagulation cascade. The primary classes of available anticoagulants include heparins, vitamin K-dependent antagonists (e.g., warfarin), direct thrombin inhibitors, and factor Xa inhibitors. Anticoagulants:
  • Prothrombin Prothrombin A plasma protein that is the inactive precursor of thrombin. It is converted to thrombin by a prothrombin activator complex consisting of factor Xa, factor V, phospholipid, and calcium ions. Hemostasis complex concentrate (PCC) and vitamin K Vitamin K A lipid cofactor that is required for normal blood clotting. Several forms of vitamin K have been identified: vitamin K 1 (phytomenadione) derived from plants, vitamin K 2 (menaquinone) from bacteria, and synthetic naphthoquinone provitamins, vitamin K 3 (menadione). Vitamin k 3 provitamins, after being alkylated in vivo, exhibit the antifibrinolytic activity of vitamin k. Green leafy vegetables, liver, cheese, butter, and egg yolk are good sources of vitamin k. Fat-soluble Vitamins and their Deficiencies, if on warfarin Warfarin An anticoagulant that acts by inhibiting the synthesis of vitamin K-dependent coagulation factors. Warfarin is indicated for the prophylaxis and/or treatment of venous thrombosis and its extension, pulmonary embolism, and atrial fibrillation with embolization. It is also used as an adjunct in the prophylaxis of systemic embolism after myocardial infarction. Warfarin is also used as a rodenticide. Anticoagulants
  • Specific reversal agents available for factor X Factor X Storage-stable glycoprotein blood coagulation factor that can be activated to factor Xa by both the intrinsic and extrinsic pathways. A deficiency of factor X, sometimes called stuart-prower factor deficiency, may lead to a systemic coagulation disorder. Hemostasis inhibitors (e.g., andexanet alfa Andexanet Alfa Anticoagulants, idarucizumab Idarucizumab Anticoagulants)
  • PCC or FFP FFP Transfusion Products, if specific agents are unavailable or delayed
• Once stabilized, consider transfer to an appropriate facility:
  • Neurologic ICU ICU Hospital units providing continuous surveillance and care to acutely ill patients. West Nile Virus
  • Availability of specialists:
    • Neurosurgeons
    • Endovascular specialists

Neuroprotective measures^{[11,13,15,16]}

Prevention of delayed cerebral ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage:

• Delayed cerebral ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage (DCI) is a major cause of death and is associated with vasospasm.
• As stated, vasospasm most frequently is observed 7–10 days after aneurysm Aneurysm An aneurysm is a bulging, weakened area of a blood vessel that causes an abnormal widening of its diameter > 1.5 times the size of the native vessel. Aneurysms occur more often in arteries than in veins and are at risk of dissection and rupture, which can be life-threatening. Thoracic Aortic Aneurysms rupture, with resolution noted after 21 days.^[17]
• Drug of choice is nimodipine Nimodipine Subarachnoid Hemorrhage.^[17]
  • Although there is no clear evidence that vasospasm is reduced by nimodipine Nimodipine Subarachnoid Hemorrhage, administration of this drug has been shown to improve neurologic outcomes.
  • Administer to patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage.
  • Start as early as possible (< 96 hours after diagnosis)
  • Recommended dose is 60 mg orally every 4 hours.
  • IV preparations are not FDA-approved: if oral route is compromised, the contents of the nimodipine Nimodipine Subarachnoid Hemorrhage capsule Capsule An envelope of loose gel surrounding a bacterial cell which is associated with the virulence of pathogenic bacteria. Some capsules have a well-defined border, whereas others form a slime layer that trails off into the medium. Most capsules consist of relatively simple polysaccharides but there are some bacteria whose capsules are made of polypeptides. Bacteroides can be extracted into a syringe and given via a nasogastric tube Nasogastric tube Malnutrition in children in resource-limited countries.
• Treatment with nimodipine Nimodipine Subarachnoid Hemorrhage is continued for 21 days.
• Maintaining euvolemia Euvolemia Volume Depletion and Dehydration is also recommended to prevent DCI.^[14,17]

Prevention of rebleeding: 

• Blood pressure control:^[17,25]
  • Goal systolic blood pressure < 160 mm Hg (avoid dropping below 130 mm Hg)
  • Goal mean arterial pressure Mean Arterial Pressure Mean arterial pressure (MAP) is the average systemic arterial pressure and is directly related to cardiac output (CO) and systemic vascular resistance (SVR). The SVR and MAP are affected by the vascular anatomy as well as a number of local and neurohumoral factors. Vascular Resistance, Flow, and Mean Arterial Pressure < 110 mm Hg
  • Avoid rapid drops in blood pressure.
  • Avoid hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension.
  • Avoid nitrates Nitrates Nitrates are a class of medications that cause systemic vasodilation (veins > arteries) by smooth muscle relaxation. Nitrates are primarily indicated for the treatment of angina, where preferential venodilation causes pooling of blood, decreased preload, and ultimately decreased myocardial O2 demand. Nitrates, as these may elevate ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP).
• Drug options for hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension:^[23]
  • Labetalol Labetalol A salicylamide derivative that is a non-cardioselective blocker of beta-adrenergic receptors and alpha-1 adrenergic receptors. Subarachnoid Hemorrhage
    • IV injection: 10–20 mg over 2 minutes; followed by 20–80 mg every 10 minutes until SBP SBP Ascites is < 160 mm Hg or mean arterial pressure Mean Arterial Pressure Mean arterial pressure (MAP) is the average systemic arterial pressure and is directly related to cardiac output (CO) and systemic vascular resistance (SVR). The SVR and MAP are affected by the vascular anatomy as well as a number of local and neurohumoral factors. Vascular Resistance, Flow, and Mean Arterial Pressure is < 100 mm Hg
    • IV infusion: 0.5–2 mg/min until a satisfactory response is achieved, then discontinue. 
  • Nicardipine Nicardipine A potent calcium channel blockader with marked vasodilator action. It has antihypertensive properties and is effective in the treatment of angina and coronary spasms without showing cardiodepressant effects. It has also been used in the treatment of asthma and enhances the action of specific antineoplastic agents. Class 4 Antiarrhythmic Drugs (Calcium Channel Blockers)
    • IV infusion: 3–5 mg/hr for 15 minutes, increased by 2.5 mg/hr every 15 minutes, adjusted to response.
    • Maximum rate: 15 mg/hr
    • Reduce dose gradually once target blood pressure is achieved.
    • Maintenance dose Maintenance Dose Dosage Calculation: 2–4 mg/hr
• Short-course tranexamic acid Tranexamic acid Antifibrinolytic hemostatic used in severe hemorrhage. Hemophilia:^[17,22]
  • Consider a 24- to 72-hour course of IV tranexamic acid Tranexamic acid Antifibrinolytic hemostatic used in severe hemorrhage. Hemophilia if endovascular coiling Endovascular Coiling Subarachnoid Hemorrhage or neurosurgical clipping is suitable but cannot be carried out within 24 hours.
  • May reduce rebleeding risk but has not been proven to improve clinical outcomes.

Consider seizure prophylaxis Prophylaxis Cephalosporins:

• Levetiracetam Levetiracetam A pyrrolidinone and acetamide derivative that is used primarily for the treatment of seizures and some movement disorders, and as a nootropic agent. Second-Generation Anticonvulsant Drugs (20 mg/kg IV loading dose Loading Dose Dosage Calculation, then 1 g IV every 12 hours) is the drug of choice.
• Phenytoin Phenytoin An anticonvulsant that is used to treat a wide variety of seizures. The mechanism of therapeutic action is not clear, although several cellular actions have been described including effects on ion channels, active transport, and general membrane stabilization. Phenytoin has been proposed for several other therapeutic uses, but its use has been limited by its many adverse effects and interactions with other drugs. First-Generation Anticonvulsant Drugs has been associated with poor outcomes.^[22]
• May be continued for months after initial insult (in those at risk for delayed seizure, e.g., intracerebral hematoma Hematoma A collection of blood outside the blood vessels. Hematoma can be localized in an organ, space, or tissue. Intussusception, prior seizure)^[17]

Management of increased ICP Increased ICP Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, intracranial. Subarachnoid Hemorrhage: 

• Head elevation to 30 degrees
• IV mannitol Mannitol A diuretic and renal diagnostic aid related to sorbitol. It has little significant energy value as it is largely eliminated from the body before any metabolism can take place. It can be used to treat oliguria associated with kidney failure or other manifestations of inadequate renal function and has been used for determination of glomerular filtration rate. Mannitol is also commonly used as a research tool in cell biological studies, usually to control osmolarity. Osmotic Diuretics:
  • Administer 0.25–1 g/kg over 30–60 minutes.
  • Repeat every 6–8 hours, as needed.
• Short-term, controlled hyperventilation Hyperventilation A pulmonary ventilation rate faster than is metabolically necessary for the exchange of gases. It is the result of an increased frequency of breathing, an increased tidal volume, or a combination of both. It causes an excess intake of oxygen and the blowing off of carbon dioxide. Respiratory Alkalosis 
• Analgesia Analgesia Methods of pain relief that may be used with or in place of analgesics. Anesthesiology: History and Basic Concepts and antiemetics Antiemetics Antiemetics are medications used to treat and/or prevent nausea and vomiting. These drugs act on different target receptors. The main classes include benzodiazepines, corticosteroids, atypical antipsychotics, cannabinoids, and antagonists of the following receptors: serotonin, dopamine, and muscarinic and neurokinin receptors. Antiemetics:
  • Pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways and vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia can raise ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP).
  • Remember to take into account the sedating effect of opiates Opiates Opiates are drugs that are derived from the sap of the opium poppy. Opiates have been used since antiquity for the relief of acute severe pain. Opioids are synthetic opiates with properties that are substantially similar to those of opiates. Opioid Analgesics when conducting neurologic assessments.

Neurosurgical and endovascular intervention^[11,17,22]

Consult neurosurgery Neurosurgery Neurosurgery is a specialized field focused on the surgical management of pathologies of the brain, spine, spinal cord, and peripheral nerves. General neurosurgery includes cases of trauma and emergencies. There are a number of specialized neurosurgical practices, including oncologic neurosurgery, spinal neurosurgery, and pediatric neurosurgery. Neurosurgery and/or endovascular interventionist as soon as a SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage is suspected! The goal is to stop the bleeding, prevent rebleeding, and manage ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP) to prevent secondary ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage. Possible interventions include:

• Surgical aneurysm clipping Surgical Aneurysm Clipping Subarachnoid Hemorrhage
• Endovascular coiling Endovascular Coiling Subarachnoid Hemorrhage
• Ventriculostomy Ventriculostomy Surgical creation of an opening in a cerebral ventricle. Neurosurgery placement
• Decompressive hemicraniectomy Hemicraniectomy Neurosurgery:
  • May be indicated to relieve ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP) in cases of intracerebral hemorrhage Intracerebral Hemorrhage Intracerebral hemorrhage (ICH) refers to a spontaneous or traumatic bleed into the brain parenchyma and is the 2nd-most common cause of cerebrovascular accidents (CVAs), commonly known as stroke, after ischemic CVAs. Intracerebral Hemorrhage
  • May be indicated to relieve ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP) in cases of severe cerebral edema Cerebral edema Increased intracellular or extracellular fluid in brain tissue. Cytotoxic brain edema (swelling due to increased intracellular fluid) is indicative of a disturbance in cell metabolism, and is commonly associated with hypoxic or ischemic injuries. An increase in extracellular fluid may be caused by increased brain capillary permeability (vasogenic edema), an osmotic gradient, local blockages in interstitial fluid pathways, or by obstruction of CSF flow (e.g., obstructive hydrocephalus). Increased Intracranial Pressure (ICP)
• Cerebrovascular imaging is recommended immediately after aneurysm Aneurysm An aneurysm is a bulging, weakened area of a blood vessel that causes an abnormal widening of its diameter > 1.5 times the size of the native vessel. Aneurysms occur more often in arteries than in veins and are at risk of dissection and rupture, which can be life-threatening. Thoracic Aortic Aneurysms repair.

Monitoring and additional management^[11,13,25]

Monitoring should be performed in an ICU ICU Hospital units providing continuous surveillance and care to acutely ill patients. West Nile Virus by specially trained staff equipped to continuously and simultaneously address the following:

• Hemodynamic instability:^[17]
  • May require central lines, arterial lines, ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP) monitor
  • Monitor for hypoxemia Hypoxemia Neonatal Respiratory Distress Syndrome and arrhythmias.
  • IV fluid infusions (usually normal saline Normal saline A crystalloid solution that contains 9. 0g of sodium chloride per liter of water. It has a variety of uses, including: as a contact lens solution, in ophthalmic solutions and nasal lavage, in wound irrigation, and for fluid therapy. Intravenous Fluids) for maintenance of euvolemia Euvolemia Volume Depletion and Dehydration
  • Avoid large amounts of hypotonic Hypotonic Solutions that have a lesser osmotic pressure than a reference solution such as blood, plasma, or interstitial fluid. Renal Sodium and Water Regulation fluids.
  • Avoid significant volume contraction.
  • Closely monitor fluid input and output.
• Neurologic deterioration:
  • Focused neurologic exam every 2 hours by qualified ICU ICU Hospital units providing continuous surveillance and care to acutely ill patients. West Nile Virus nurse
  • Emergent CT for any acute deterioration
  • Transcranial Doppler Doppler Ultrasonography applying the doppler effect, with frequency-shifted ultrasound reflections produced by moving targets (usually red blood cells) in the bloodstream along the ultrasound axis in direct proportion to the velocity of movement of the targets, to determine both direction and velocity of blood flow. Ultrasound (Sonography) can be used to monitor for vasospasm (arterial narrowing or change in blood velocity).^[17]
• Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever:
  • Increases cerebral metabolic rate^[24]
  • Antipyretics and cooling measures as indicated to achieve normothermia^[17]
• ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP):
  • Ventriculostomy Ventriculostomy Surgical creation of an opening in a cerebral ventricle. Neurosurgery: Intracranial line placed by neurosurgical staff to monitor ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP).
  • Ventriculostomy Ventriculostomy Surgical creation of an opening in a cerebral ventricle. Neurosurgery also allows for drainage of CSF to reduce ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP).
• Electrolyte imbalance:
  • Hyponatremia Hyponatremia Hyponatremia is defined as a decreased serum sodium (sNa+) concentration less than 135 mmol/L. Serum sodium is the greatest contributor to plasma osmolality, which is very tightly controlled via antidiuretic hormone (ADH) release from the hypothalamus and by the thirst mechanism. Hyponatremia is especially common in this setting.
  • IV fluid choice and drip rate may be adjusted to maintain eunatremia.
  • Hyperglycemia Hyperglycemia Abnormally high blood glucose level. Diabetes Mellitus is associated with poor outcomes, so the following are recommended:
    • Glucose Glucose A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement. Lactose Intolerance monitoring 
    • Maintenance of euglycemia with insulin Insulin Insulin is a peptide hormone that is produced by the beta cells of the pancreas. Insulin plays a role in metabolic functions such as glucose uptake, glycolysis, glycogenesis, lipogenesis, and protein synthesis. Exogenous insulin may be needed for individuals with diabetes mellitus, in whom there is a deficiency in endogenous insulin or increased insulin resistance. Insulin protocol
• When hydrocephalus Hydrocephalus Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, intracranial. Subarachnoid Hemorrhage is present:^[11]
  • Acute hydrocephalus Hydrocephalus Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, intracranial. Subarachnoid Hemorrhage is usually managed by external ventricular drainage or lumbar drainage. 
  • Chronic hydrocephalus Hydrocephalus Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, intracranial. Subarachnoid Hemorrhage is usually managed with a ventricular shunt. 
• Deep vein thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus ( DVT DVT Deep vein thrombosis (DVT) usually occurs in the deep veins of the lower extremities. The affected veins include the femoral, popliteal, iliofemoral, and pelvic veins. Proximal DVT is more likely to cause a pulmonary embolism (PE) and is generally considered more serious. Deep Vein Thrombosis)/ pulmonary embolism Pulmonary Embolism Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Pulmonary Embolism (PE) prophylaxis Prophylaxis Cephalosporins:
  • Mechanical means are preferred. 
  • Anticoagulants Anticoagulants Anticoagulants are drugs that retard or interrupt the coagulation cascade. The primary classes of available anticoagulants include heparins, vitamin K-dependent antagonists (e.g., warfarin), direct thrombin inhibitors, and factor Xa inhibitors. Anticoagulants are generally avoided until definitive repair has been undertaken.

Follow-up^[5,9,11]

• Care plan:
  • Develop and document a personalized care plan, including details of follow-up care.
  • Give a copy to the patient (or family/caregivers).
  • Include details of whom to contact at the specialist center for ongoing advice and support. 
• Neuroimaging Neuroimaging Non-invasive methods of visualizing the central nervous system, especially the brain, by various imaging modalities. Febrile Infant:
  • Consider follow-up neuroimaging Neuroimaging Non-invasive methods of visualizing the central nervous system, especially the brain, by various imaging modalities. Febrile Infant for people with an aneurysmal SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage. 
  • The frequency of follow-up imaging is based on:
    • Type and outcome of any neurosurgical or endovascular intervention 
    • Presence of non-culprit aneurysms: A multidisciplinary team including a neuroradiologist and a neurosurgeon should evaluate options for these. 
    • Estimated risk of rebleeding 
    • Risk of planned/subsequent interventions 
    • Patient’s preference 
• Ongoing measures:
  • Encourage smoking Smoking Willful or deliberate act of inhaling and exhaling smoke from burning substances or agents held by hand. Interstitial Lung Diseases cessation and direct to support resources/groups. 
  • Antiplatelet and anticoagulation Anticoagulation Pulmonary Hypertension Drugs medication:
    • Do not withhold solely on the basis of SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage if the culprit aneurysm Aneurysm An aneurysm is a bulging, weakened area of a blood vessel that causes an abnormal widening of its diameter > 1.5 times the size of the native vessel. Aneurysms occur more often in arteries than in veins and are at risk of dissection and rupture, which can be life-threatening. Thoracic Aortic Aneurysms has been secured by coiling or clipping. 
    • Balance harm of not taking medication with risk of future SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage.
  • Headaches:
    • Common, generally benign Benign Fibroadenoma 
    • May be due to chronic hydrocephalus Hydrocephalus Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, intracranial. Subarachnoid Hemorrhage if the person has features of raised ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP).
• Screening Screening Preoperative Care: It is reasonable to offer screening Screening Preoperative Care ( neuroimaging Neuroimaging Non-invasive methods of visualizing the central nervous system, especially the brain, by various imaging modalities. Febrile Infant) to 1st-degree relatives of patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with SAH SAH Subarachnoid hemorrhage (SAH) is a type of cerebrovascular accident (stroke) resulting from intracranial hemorrhage into the subarachnoid space between the arachnoid and the pia mater layers of the meninges surrounding the brain. Most SAHs originate from a saccular aneurysm in the circle of Willis but may also occur as a result of trauma, uncontrolled hypertension, vasculitis, anticoagulant use, or stimulant use. Subarachnoid Hemorrhage for saccular aneurysms Saccular aneurysms Brain Aneurysms.

Prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas^[5]

• Early mortality Mortality All deaths reported in a given population. Measures of Health Status rates as high as 10%–20%
• 1-year mortality Mortality All deaths reported in a given population. Measures of Health Status as high as 20%–25%
• Survivors may have significant morbidity Morbidity The proportion of patients with a particular disease during a given year per given unit of population. Measures of Health Status:
  • Increased incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency of cardiovascular events
  • Neurologic, cognitive, and memory Memory Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory. Psychiatric Assessment deficits are common.
  • Sleep Sleep A readily reversible suspension of sensorimotor interaction with the environment, usually associated with recumbency and immobility. Physiology of Sleep disorders and mood disorders are common.
  • Persistent seizure disorder is common.
  • Anosmia Anosmia Complete or severe loss of the subjective sense of smell. Loss of smell may be caused by many factors such as a cold, allergy, olfactory nerve diseases, viral respiratory tract infections (e.g., COVID-19), aging and various neurological disorders (e.g., Alzheimer disease). Cranial Nerve Palsies is common.

Differential Diagnosis

• Ischemic stroke Ischemic Stroke An ischemic stroke (also known as cerebrovascular accident) is an acute neurologic injury that occurs as a result of brain ischemia; this condition may be due to cerebral blood vessel occlusion by thrombosis or embolism, or rarely due to systemic hypoperfusion. Ischemic Stroke: an ischemic infarct Infarct Area of necrotic cells in an organ, arising mainly from hypoxia and ischemia Ischemic Cell Damage of the cerebral parenchyma caused by occlusion of a cerebral artery by atherosclerotic lesions or cardioembolic emboli. Ischemic stroke Ischemic Stroke An ischemic stroke (also known as cerebrovascular accident) is an acute neurologic injury that occurs as a result of brain ischemia; this condition may be due to cerebral blood vessel occlusion by thrombosis or embolism, or rarely due to systemic hypoperfusion. Ischemic Stroke presents with neurologic deficits Neurologic Deficits High-Risk Headaches and/or altered mental status Altered Mental Status Sepsis in Children/level of consciousness that depends on the size and location of the infarct Infarct Area of necrotic cells in an organ, arising mainly from hypoxia and ischemia Ischemic Cell Damage. Diagnosis is clinical and confirmed by neuroimaging Neuroimaging Non-invasive methods of visualizing the central nervous system, especially the brain, by various imaging modalities. Febrile Infant. Management includes initial stabilization, possible cerebrovascular intervention, addressing identifiable underlying etiologies ( severe hypertension Severe hypertension A confirmed blood pressure ≥ 180 mm Hg systolic and/or ≥ 120 mm Hg diastolic. Uncontrolled Hypertension, embolus), and management of cardiovascular risk factors. 
• Other hemorrhagic cerebral conditions: carotid/cerebral artery dissection, epidural hemorrhage Epidural Hemorrhage Epidural hemorrhage (EDH) is an event characterized by bleeding into the epidural space between the dural layers of the meninges and the skull. The primary mechanism triggering bleeding is trauma (i.e., closed head injury), which causes arterial injury, most commonly middle meningeal artery injury. Epidural Hemorrhage, intraparenchymal hemorrhage, and subdural hemorrhage Subdural Hemorrhage Subdural hemorrhage (SDH) is bleeding into the space between the dural and arachnoid meningeal layers surrounding the brain. The most common mechanism triggering the bleeding event is trauma (e.g., closed head injury) causing a tearing injury to the extracerebral “bridging” veins. Subdural Hemorrhage are other hemorrhagic manifestations of the cerebral vasculature that can present with neurologic deficits Neurologic Deficits High-Risk Headaches and/or altered mental status Altered Mental Status Sepsis in Children/level of consciousness. Diagnosis is clinical and confirmed by neuroimaging Neuroimaging Non-invasive methods of visualizing the central nervous system, especially the brain, by various imaging modalities. Febrile Infant. Management depends on the hemorrhagic etiology and includes initial stabilization, neurosurgical/endovascular consultation, management of ICP ICP Normal intracranial pressure (ICP) is defined as < 15 mm Hg, whereas pathologically increased ICP is any pressure ≥ 20 mm Hg. Increased ICP may result from several etiologies, including trauma, intracranial hemorrhage, mass lesions, cerebral edema, increased CSF production, and decreased CSF absorption. Increased Intracranial Pressure (ICP), and monitoring in a neurologic ICU ICU Hospital units providing continuous surveillance and care to acutely ill patients. West Nile Virus. 
• Hypertensive encephalopathy Encephalopathy Hyper-IgM Syndrome: neurologic deficit and/or altered mental status Altered Mental Status Sepsis in Children/level of consciousness that presents in the setting of severe hypertension Severe hypertension A confirmed blood pressure ≥ 180 mm Hg systolic and/or ≥ 120 mm Hg diastolic. Uncontrolled Hypertension. Diagnosis is based on the presence of elevated blood pressure and neurologic signs/symptoms. Neuroimaging Neuroimaging Non-invasive methods of visualizing the central nervous system, especially the brain, by various imaging modalities. Febrile Infant is useful to rule out ischemic or hemorrhagic cerebrovascular accident Cerebrovascular accident An ischemic stroke (also known as cerebrovascular accident) is an acute neurologic injury that occurs as a result of brain ischemia; this condition may be due to cerebral blood vessel occlusion by thrombosis or embolism, or rarely due to systemic hypoperfusion. Ischemic Stroke. Management centers around careful acute lowering of the blood pressure and long-term blood pressure management.