Functional Neurological Symptom Disorder (Conversion Disorder)

Epidemiology and Etiology

Epidemiology

• Estimated prevalence Prevalence The total number of cases of a given disease in a specified population at a designated time. It is differentiated from incidence, which refers to the number of new cases in the population at a given time. Measures of Disease Frequency varies, with the highest prevalence Prevalence The total number of cases of a given disease in a specified population at a designated time. It is differentiated from incidence, which refers to the number of new cases in the population at a given time. Measures of Disease Frequency found in neurology clinics.
• More common in women and patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship of low socioeconomic status 
• Manifests in adolescence and early adulthood
• More prevalent in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with neurologic or psychiatric comorbidities Comorbidities The presence of co-existing or additional diseases with reference to an initial diagnosis or with reference to the index condition that is the subject of study. Comorbidity may affect the ability of affected individuals to function and also their survival; it may be used as a prognostic indicator for length of hospital stay, cost factors, and outcome or survival. St. Louis Encephalitis Virus

Etiology

• Exact etiology is unknown. 
• Thought to be a combination of psychodynamic, developmental, biological, and social pathology 
• Stressful life events have been shown to be potential triggers for the physical symptoms. 
• There is evidence for impaired communication Communication The exchange or transmission of ideas, attitudes, or beliefs between individuals or groups. Decision-making Capacity and Legal Competence between the amygdala Amygdala Almond-shaped group of basal nuclei anterior to the inferior horn of the lateral ventricle of the temporal lobe. The amygdala is part of the limbic system. Limbic System: Anatomy and supplementary motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology area, causing excessive cortical arousal.

Clinical Presentation

Functional neurological symptom disorder presents with neurologic symptoms that are inconsistent with structural disease. 

• Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship may present with sensory Sensory Neurons which conduct nerve impulses to the central nervous system. Nervous System: Histology complaints that do not map to known nerve distributions (e.g., weakness/paresthesia in the entire leg Leg The lower leg, or just “leg” in anatomical terms, is the part of the lower limb between the knee and the ankle joint. The bony structure is composed of the tibia and fibula bones, and the muscles of the leg are grouped into the anterior, lateral, and posterior compartments by extensions of fascia. Leg: Anatomy).
• Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship showing non-epileptiform 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 may have abnormal features (eyes closed tightly) and should be evaluated with video EEG EEG Seizures.

Common motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology symptoms:

• Non-epileptic 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 (psychogenic 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)
• Tremor Tremor Cyclical movement of a body part that can represent either a physiologic process or a manifestation of disease. Intention or action tremor, a common manifestation of cerebellar diseases, is aggravated by movement. In contrast, resting tremor is maximal when there is no attempt at voluntary movement, and occurs as a relatively frequent manifestation of parkinson disease. Myotonic Dystrophies (psychogenic tremor Tremor Cyclical movement of a body part that can represent either a physiologic process or a manifestation of disease. Intention or action tremor, a common manifestation of cerebellar diseases, is aggravated by movement. In contrast, resting tremor is maximal when there is no attempt at voluntary movement, and occurs as a relatively frequent manifestation of parkinson disease. Myotonic Dystrophies)
• Impaired gait Gait Manner or style of walking. Neurological Examination
• Weakness/paralysis

Common sensory Sensory Neurons which conduct nerve impulses to the central nervous system. Nervous System: Histology symptoms:

• Anesthesia Anesthesia A state characterized by loss of feeling or sensation. This depression of nerve function is usually the result of pharmacologic action and is induced to allow performance of surgery or other painful procedures. Anesthesiology: History and Basic Concepts
• Vision Vision Ophthalmic Exam impairment ( blindness Blindness The inability to see or the loss or absence of perception of visual stimuli. This condition may be the result of eye diseases; optic nerve diseases; optic chiasm diseases; or brain diseases affecting the visual pathways or occipital lobe. Retinopathy of Prematurity, decreased visual field Visual Field The Visual Pathway and Related Disorders)
• Hearing impairment Hearing impairment Hearing loss, also known as hearing impairment, is any degree of impairment in the ability to apprehend sound as determined by audiometry to be below normal hearing thresholds. Clinical presentation may occur at birth or as a gradual loss of hearing with age, including a short-term or sudden loss at any point. Hearing Loss
• Hallucinations Hallucinations Subjectively experienced sensations in the absence of an appropriate stimulus, but which are regarded by the individual as real. They may be of organic origin or associated with mental disorders. Schizophrenia

Diagnosis

General approach

• Associated with so-called la belle indifference: Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship appear to be inappropriately unconcerned with their symptoms given their level of disability Disability Determination of the degree of a physical, mental, or emotional handicap. The diagnosis is applied to legal qualification for benefits and income under disability insurance and to eligibility for social security and workman’s compensation benefits. ABCDE Assessment.
• History and physical exam should begin from the patient in the waiting room until the patient leaves the office, as inconsistencies are likely to be found.
• Baseline investigations may include:
  • CBC
  • Basic metabolic panel Basic Metabolic Panel Primary vs Secondary Headaches
  • Liver function tests Liver function tests Liver function tests, also known as hepatic function panels, are one of the most commonly performed screening blood tests. Such tests are also used to detect, evaluate, and monitor acute and chronic liver diseases. Liver Function Tests
  • Thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy panel
  • Urinalysis Urinalysis Examination of urine by chemical, physical, or microscopic means. Routine urinalysis usually includes performing chemical screening tests, determining specific gravity, observing any unusual color or odor, screening for bacteriuria, and examining the sediment microscopically. Urinary Tract Infections (UTIs) in Children
  • Toxicology screen
  • Imaging may be required.

Diagnostic criteria

• ≥ 1 motor Motor Neurons which send impulses peripherally to activate muscles or secretory cells. Nervous System: Histology or sensory Sensory Neurons which conduct nerve impulses to the central nervous system. Nervous System: Histology impairment
• Inconsistency between reported symptoms and physical exam findings
• Absence of a diagnosed clinical entity that explains the symptoms 
• Social, occupational, or other dysfunction related to distress caused by the symptoms

Specific findings

The following 2 tests may help differentiate functional neurological symptom disorder from organic disease, if the respective neurological deficits are present.

• Hoover’s sign:
  • Diagnostic test to differentiate organic from non-organic leg Leg The lower leg, or just “leg” in anatomical terms, is the part of the lower limb between the knee and the ankle joint. The bony structure is composed of the tibia and fibula bones, and the muscles of the leg are grouped into the anterior, lateral, and posterior compartments by extensions of fascia. Leg: Anatomy paresis Paresis A general term referring to a mild to moderate degree of muscular weakness, occasionally used as a synonym for paralysis (severe or complete loss of motor function). In the older literature, paresis often referred specifically to paretic neurosyphilis. ‘general paresis’ and ‘general paralysis’ may still carry that connotation. Bilateral lower extremity paresis is referred to as paraparesis. Spinal Disk Herniation
  • Patient must be supine; examiner cups both hands under the patient’s heels.
  • Patient is instructed to flex the hip of the non-paretic leg Leg The lower leg, or just “leg” in anatomical terms, is the part of the lower limb between the knee and the ankle joint. The bony structure is composed of the tibia and fibula bones, and the muscles of the leg are grouped into the anterior, lateral, and posterior compartments by extensions of fascia. Leg: Anatomy. 
  • Examiner should feel the contralateral heel press down into their palm. 
  • When the patient is asked to flex the hip of the paretic leg Leg The lower leg, or just “leg” in anatomical terms, is the part of the lower limb between the knee and the ankle joint. The bony structure is composed of the tibia and fibula bones, and the muscles of the leg are grouped into the anterior, lateral, and posterior compartments by extensions of fascia. Leg: Anatomy, the examiner should similarly feel the contralateral heel press down into their palm. 
  • Positive: failure of the contralateral heel to depress → hip girdle is not being activated to lift the paretic leg Leg The lower leg, or just “leg” in anatomical terms, is the part of the lower limb between the knee and the ankle joint. The bony structure is composed of the tibia and fibula bones, and the muscles of the leg are grouped into the anterior, lateral, and posterior compartments by extensions of fascia. Leg: Anatomy → suggestive of functional neurological symptom disorder 
• Drop arm Arm The arm, or “upper arm” in common usage, is the region of the upper limb that extends from the shoulder to the elbow joint and connects inferiorly to the forearm through the cubital fossa. It is divided into 2 fascial compartments (anterior and posterior). Arm: Anatomy test: 
  • While patient is lying down, raise the impaired arm Arm The arm, or “upper arm” in common usage, is the region of the upper limb that extends from the shoulder to the elbow joint and connects inferiorly to the forearm through the cubital fossa. It is divided into 2 fascial compartments (anterior and posterior). Arm: Anatomy above the patient and release. 
  • In patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with functional neurological symptom disorder, the arm Arm The arm, or “upper arm” in common usage, is the region of the upper limb that extends from the shoulder to the elbow joint and connects inferiorly to the forearm through the cubital fossa. It is divided into 2 fascial compartments (anterior and posterior). Arm: Anatomy will not hit the face.

Management and Prognosis

Management

• Clinicians must assure patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship that their symptoms are real, but do not represent irreversible damage.  
• Establishing good rapport as well as working in a multidisciplinary team is important. 
• Treatment of choice is psychotherapy Psychotherapy Psychotherapy is interpersonal treatment based on the understanding of psychological principles and mechanisms of mental disease. The treatment approach is often individualized, depending on the psychiatric condition(s) or circumstance. Psychotherapy, usually CBT. 
• Physical and occupational therapy Occupational Therapy Skilled treatment that helps individuals achieve independence in all facets of their lives. It assists in the development of skills needed for independent living. Fetal Alcohol Spectrum Disorder for evaluation and treatment of underlying distress.
• Utilize pharmacotherapy when there are other comorbid psychiatric illnesses such as depression or anxiety Anxiety Feelings or emotions of dread, apprehension, and impending disaster but not disabling as with anxiety disorders. Generalized Anxiety Disorder.

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

• Relatively poor with low response to current treatment modalities 
• Higher patient confidence in physician as well as shorter duration of symptoms are associated with better outcome.

Differential Diagnosis

• Myasthenia gravis Myasthenia Gravis Myasthenia gravis (MG) is an autoimmune neuromuscular disorder characterized by weakness and fatigability of skeletal muscles caused by dysfunction/destruction of acetylcholine receptors at the neuromuscular junction. MG presents with fatigue, ptosis, diplopia, dysphagia, respiratory difficulties, and progressive weakness in the limbs, leading to difficulty in movement. Myasthenia Gravis (MG): an autoimmune neuromuscular disorder caused by dysfunction of acetylcholine Acetylcholine A neurotransmitter found at neuromuscular junctions, autonomic ganglia, parasympathetic effector junctions, a subset of sympathetic effector junctions, and at many sites in the central nervous system. Receptors and Neurotransmitters of the CNS receptors Receptors Receptors are proteins located either on the surface of or within a cell that can bind to signaling molecules known as ligands (e.g., hormones) and cause some type of response within the cell. Receptors at the neuromuscular junction Neuromuscular junction The synapse between a neuron and a muscle. Skeletal Muscle Contraction. The condition presents with fatigue Fatigue The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli. Fibromyalgia, ptosis Ptosis Cranial Nerve Palsies, diplopia Diplopia A visual symptom in which a single object is perceived by the visual cortex as two objects rather than one. Disorders associated with this condition include refractive errors; strabismus; oculomotor nerve diseases; trochlear nerve diseases; abducens nerve diseases; and diseases of the brain stem and occipital lobe. Myasthenia Gravis, dysphagia Dysphagia Dysphagia is the subjective sensation of difficulty swallowing. Symptoms can range from a complete inability to swallow, to the sensation of solids or liquids becoming “stuck.” Dysphagia is classified as either oropharyngeal or esophageal, with esophageal dysphagia having 2 sub-types: functional and mechanical. Dysphagia, respiratory difficulties, and progressive weakness in the limbs leading to difficulty in movement. Diagnosis is established based on clinical presentation as well as detection of antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions and electrophysiologic studies, which are negative in functional neurological symptom disorder.
• Somatic symptom disorder Somatic symptom disorder Somatic symptom disorder (SSD) is a condition characterized by the presence of 1 or more physical symptoms associated with excessive thoughts and feelings about symptom severity. Symptoms are usually not dangerous, but the patient devotes excessive time and energy to figuring out their underlying cause and how to treat them. Somatic Symptom Disorder ( SSD SSD Somatic symptom disorder (SSD) is a condition characterized by the presence of 1 or more physical symptoms associated with excessive thoughts and feelings about symptom severity. Symptoms are usually not dangerous, but the patient devotes excessive time and energy to figuring out their underlying cause and how to treat them. Somatic Symptom Disorder): a condition in which patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship present with 1 or multiple somatic complaints and excessive thoughts and concern about the severity of their symptoms. Management is with CBT. Somatic symptom disorder Somatic symptom disorder Somatic symptom disorder (SSD) is a condition characterized by the presence of 1 or more physical symptoms associated with excessive thoughts and feelings about symptom severity. Symptoms are usually not dangerous, but the patient devotes excessive time and energy to figuring out their underlying cause and how to treat them. Somatic Symptom Disorder is a diagnosis of exclusion as there are no exam findings, unlike in functional neurological symptom disorder.  
• Illness anxiety Anxiety Feelings or emotions of dread, apprehension, and impending disaster but not disabling as with anxiety disorders. Generalized Anxiety Disorder disorder: a condition characterized by prolonged and exaggerated concern about one’s health and possible illness. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship fear or are convinced that they have a disease and interpret minor or normal bodily symptoms as signs of serious medical conditions. Management is with CBT. Those with functional neurological symptom disorder do not exhibit the excessive worry found in illness anxiety Anxiety Feelings or emotions of dread, apprehension, and impending disaster but not disabling as with anxiety disorders. Generalized Anxiety Disorder disorder.