Functional neurologic symptom disorder
Functional neurologic symptom disorder (conversion disorder) causes real, involuntary weakness, sensory loss, movement abnormality, or non-epileptic attacks that are incompatible with recognized neurologic disease on careful examination. Diagnosis rests on positive bedside signs of incongruity (Hoover sign, tremor entrainment) rather than exclusion alone; first-line treatment is diagnosis explanation plus physiotherapy or cognitive behavioral therapy, not antiseizure or other disease-specific drugs.
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What this article covers
- Overview
Definition: functional neurologic symptom disorder (FNSD), also called conversion disorder, is one or more symptoms of altered voluntary motor or sensory function that are incompatible with a…
- Epidemiology
Common in neurology practice: functional symptoms account for a substantial share of new neurology outpatient referrals and are among the more frequent diagnoses seen in general neurology clinics.
- Risk factors
Prior psychological trauma: a history of physical, sexual, or emotional abuse, combat exposure, or other significant adverse life events is a commonly identified antecedent.
- Pathophysiology
A disorder of nervous system function, not structure: neuroimaging and neurophysiologic studies have not identified a consistent structural lesion; functional imaging instead shows altered activity…
- Clinical features
Functional weakness or paralysis: limb or facial weakness that does not follow a pyramidal, root, or peripheral nerve pattern, with variability in strength across the exam or from visit to visit.
- Differential diagnosis
True neurologic disease matching the anatomic pattern (stroke, myelopathy, peripheral neuropathy, myasthenia gravis): weakness or sensory loss follows a consistent, reproducible anatomic distribution…
- Diagnosis
Clinical diagnosis established by positive signs of physiologic incompatibility, not by exclusion alone: the diagnosis requires internal inconsistency between the reported deficit and objective…
- Management
First, deliver the diagnosis clearly using the positive examination findings, validating that the symptoms are real and not intentionally produced, since how it is communicated predicts treatment engagement.
- Complications
Iatrogenic harm from repeated, unnecessary testing: invasive procedures, unneeded medications, and their side effects accumulate when diagnosis is delayed or repeatedly doubted.
- Prognosis
Generally favorable with early, clearly communicated diagnosis and prompt rehabilitation: patients with acute-onset symptoms and short duration before diagnosis have substantial or complete recovery.
- Prevention
No primary prevention strategy exists for FNSD, since the underlying psychological vulnerabilities are not readily modifiable in advance.
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