Conversion Disorder (Functional Neurological Disorder)

Conversion Disorder (also known as Functional Neurological Symptom Disorder or Functional Neurological Disorder [FND]) is a mental disorder characterized by neurologic symptoms (either motor or sensory) that is incompatible with any known neurologic disease. Common symptoms include weakness and/or paralysis, non-epileptic seizures, movement disorders, speech or visual impairment, swallowing difficulty, sensory disturbances, or cognitive symptoms.

Risk Factors

Many clinicians use the alternative names of “functional” (referring to abnormal central nervous system functioning) or “psychogenic” (referring to a “psychiatric” etiology) to describe the symptoms of conversion disorder.

Criterion A

1 or more symptoms of altered voluntary motor or sensory function.

Note: Autonomic symptoms such as orthostatic lightheadedness would not meet Criterion A!

Criterion B

Clinical findings provide evidence of incompatibility between the symptom and recognized neurological or medical conditions. 

Criterion C

The symptom or deficit is not better explained by another medical or mental disorder.

Criterion D

The symptom or deficit causes clinically significant distress or impairment in social, occupational, or other important areas of functioning or warrants medical evaluation.

Symptom Type Specifiers

Specify symptom type:

  • With weakness or paralysis
  • With abnormal movement (e.g. - tremor, dystonic movement, myoclonus, gait disorder)
  • With swallowing symptoms
  • With speech symptom (e.g. - aphasia, dysphonia, slurred speech)
  • With seizure attacks or seizures
  • With anesthesia or sensory loss

  • With special sensory symptom (e.g. - visual, olfactory, or hearing disturbance)
  • With mixed symptoms

Episode and Stressor Specifier

Specify if:

  • Acute episode: Symptoms present for less than 6 months.
  • Persistent: Symptoms occurring for 6 months or more.

Specify if:

  • With psychological stressor (specify stressor)
  • Without psychological stressor
  • Another mental disorder
    • If another mental disorder better explains the symptoms, that diagnosis should be made. However the diagnosis of conversion disorder may be made in the presence of another mental disorder.
  • Neurological disease
    • The main differential diagnosis is neurological disease that might better explain the symptoms. After a thorough neurological assessment, an unexpected neurological disease cause for the symptoms is rarely found at follow up. However, reassessment may be required if the symptoms appear to be progressive. Conversion disorder may coexist with neurological disease.
    • Conversion disorder may be diagnosed in addition to somatic symptom disorder. Most of the somatic symptoms encountered in somatic symptom disorder cannot be demonstrated to be clearly incompatible with pathophysiology (e.g., pain, fatigue), whereas in conversion disorder, such incompatibility is required for the diagnosis. The excessive thoughts, feelings, and behaviours characterizing somatic symptom disorder are often absent in conversion disorder.
    • The diagnosis of conversion disorder does not require the judgment that the symptoms are not intentionally produced (i.e. - not feigned), because assessment of conscious intention is unreliable. However definite evidence of feigning (e.g. - clear evidence that loss of function is present during the examination but not at home) would suggest a diagnosis of factitious disorder if the individual's apparent aim is to assume the sick role or malingering if the aim is to obtain an incentive such as money.
    • Dissociative symptoms are common in individuals with conversion disorder. If both conversion disorder and a dissociative disorder are present, both diagnoses should be made.
    • Individuals with body dysmorphic disorder are excessively concerned about a perceived defect in their physical features but do not complain of symptoms of sensory or motor functioning in the affected body part.
    • In depressive disorders, individuals may report general heaviness of their limbs, whereas the weakness of conversion disorder is more focal and prominent. Depressive disorders are also differentiated by the presence of core depressive symptoms.
    • Episodic neurological symptoms (e.g., tremors and paresthesias) can occur in both conversion disorder and panic attacks. In panic attacks, the neurological symptoms are typically transient and acutely episodic with characteristic cardiorespiratory symptoms. Loss of awareness with amnesia for the attack and violent limb movements occur in non-epileptic attacks, but not in panic attacks.

Comparison of Somatic Symptom Disorders, Factitious Disorder, and Malingering Fig. 1

  • Hoover's sign
    • Weakness of hip extension returns to normal strength with contralateral hip flexion against resistance.
  • Weakness
    • Marked weakness of ankle plantar-flexion when tested on the bed in an individual who is able to walk on tiptoes
  • Tremor entrainment test.
    • A unilateral tremor may be functional if the tremor changes when the individual is distracted away from it. This may be observed if the individual is asked to copy the examiner in making a rhythmical movement with their unaffected hand and this causes the functional tremor to change such that it copies or “entrains” to the rhythm of the unaffected hand or the functional tremor is suppressed, or no longer makes a simple rhythmical movement.
  • Seizures
    • In attacks resembling epilepsy or syncope (“psychogenic” non-epileptic attacks), the occurrence of closed eyes with resistance to opening or a normal simultaneous electroencephalogram (although this alone does not exclude all forms of epilepsy or syncope)
  • Visual blindness
    • A tubular visual field (i.e. - tunnel vision) may indicate conversion
    • In patients reporting severe monocular or binocular limitations, normal visual evoked potential (VEP) results plus a normal neuro-ophthalmic examination is strongly suggestive of functional origin.[1]
    • Normal pupillary reflexes and preserved optokinetic nystagmus suggest grossly intact subcortical and cortical visual pathways and therefore a functional
    • Electrophysiological testing and structural neuroimaging is often needed to confirm the diagnosis of functional blindness, so as to rule out cortical pathology, including cortical blindness.

Education and self-help techniques is the most important first-line treatment

Cognitive behavioural therapy has good second-line evidence.

Physical therapy is recommended for motor symptoms of conversion disorder.