Conversion Disorder (Functional Neurological Symptom Disorder)
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Direct answer
Conversion disorder is the involuntary loss or alteration of motor or sensory function — seizures, paralysis, blindness, aphonia, tremor or sensory loss — that resembles a neurological disease but shows internal inconsistency and is associated with psychological stressors. ICD-10 classifies it among dissociative (conversion) disorders because the symptom is seen as an unconscious resolution of distress, whereas DSM-5 calls it functional neurological symptom disorder and stresses positive clinical signs rather than the absence of disease. Diagnosis requires incompatibility between the symptom and recognised neurological conditions, and management combines reassurance, physiotherapy, psychotherapy and treatment of comorbid depression or anxiety.
What you must remember
- Diagnostic standard: positive signs of internal inconsistency — Hoover sign (weak hip extension returns when the other leg pushes down), tubular visual fields, tremor entrainment, eyes closed during pseudoseizures and midline-splitting sensory loss.
- Pseudoseizure clues: gradual onset, asynchronous thrashing, pelvic thrusting, eyes firmly closed, prolonged duration, talking during the event and a normal ictal EEG without prolactin rise; incontinence and self-injury do not exclude it.
- La belle indifférence: classical calm detachment about disabling symptoms — traditionally asked, though its absence does not exclude the diagnosis.
- Classification: ICD-10 groups it with dissociative disorders (dissociative motor disorder, convulsions, anaesthesia); DSM-5 uses functional neurological symptom disorder and dropped the required stressor.
- Epidemiology: commoner in rural settings, lower educational attainment, adolescents and young adults, and after acute psychosocial stress; a neurological disease explains symptoms in only a small minority of modern series.
- Management: communicate the positive diagnosis confidently, restore function early with graded physiotherapy, add cognitive behaviour or psychodynamic therapy, and treat comorbid depression or anxiety.
- Prognosis: acute-onset, short-duration, stress-linked motor symptoms do best; chronic weakness and pseudoseizures relapse.
Common confusion
The examiner's favourite is conversion disorder versus organic disease: conversion weakness shows Hoover sign and gives way inconsistently, whereas organic hemiparesis shows consistent pyramidal-pattern weakness with tone and reflex changes. Equally examinable is pseudoseizure versus epileptic seizure — video-EEG telemetry is the gold standard when the two coexist, which happens in a notable proportion of patients. Finally, conversion is unconscious in both production and motivation, separating it from factitious disorder (conscious production, unconscious motivation) and malingering (conscious production and conscious external gain).
Exam-focused takeaway
NEET-PG presents a young woman after a family conflict with a non-physiological deficit and normal imaging, expecting conversion disorder and a positive sign such as Hoover sign as the diagnostic clue. One-liners test la belle indifférence, the ICD-10 dissociative family, the video-EEG approach to pseudoseizures, and the conscious-unconscious ladder versus malingering. Management questions reward early rehabilitation and psychotherapy rather than invasive investigations, and caution that anticonvulsants have no role in pure dissociative convulsions.
Frequently asked questions
What is conversion disorder?
Involuntary motor or sensory alteration mimicking neurological disease but showing internal inconsistency on examination.
What is the Hoover sign?
Weak hip extension that becomes strong when the opposite leg presses down, demonstrating functional weakness.
How are pseudoseizures distinguished from epileptic seizures?
Gradual onset, eye closure, asynchronous movements and normal ictal EEG; video-EEG is definitive.
What is la belle indifférence?
Striking lack of concern about a disabling symptom — classical but neither universal nor diagnostic.
Where does ICD-10 place conversion disorder?
Among the dissociative disorders, as dissociative motor disorder, convulsions or anaesthesia.
What is the best management approach?
Confident positive diagnosis, early graded physiotherapy, psychotherapy and treatment of comorbid mood disorder.