2nd February 2024

Conversion disorder/ Functional neurological symptom disorder

Conversion Disorder (also known as Functional Neurological Symptom Disorder [FNSD]) is an illness characterised by neurological complaints (either motor or sensory). These symptoms are irreconcilable with any other neurological conditions or illness. People with conversion disorder may experience some common features, including impaired vision, speech or hearing, weakness of upper or lower limbs, seizures and memory issues. 

Functional denotes abnormal CNS functioning VS Psychogenic refers to psychological causes

Clinical presentation

Motor symptoms

• Weakness, Paralysis
• Abnormal movements, tremors, shakes, seizures
• Gait abnormalities
• Abnormal limb posturing

Sensory symptoms

• Numbness
• Reduced or absent sensation
• Reduced or absent hearing
• Reduced or absent vision

Others

• Abnormal speech or abnormal volume
• Diplopia
• Difficulty swallowing or a lump in the throat
• Nonresponsive or Comatose
• General weakness

Epidemiology

• About 1/3rd of new patients seen in neurology clinics have symptoms that are either not at all or only partly explained by structural neurologic disease. About 1/5th of patients in general hospital settings might present with Conversion disorder.
• Usually seen in middle age (35 to 50).
• About a quarter of them have a co-morbid neurological disorder.
• NEAD- Non-epileptic attack disorder is seen in 2-5/10000

Criteria (DSM 5)

Criteria A

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

Criteria B

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

Criteria C

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

Criteria D

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

Risk Factors

• Maladaptive personality
• Childhood abuse
• Neglect
• Stressful life events
• Similar neurological conditions in the family or the individual

Diagnosis

History 

In addition to the usual history, the following points are important to consider:

• Dissociation at the time of the disorder is a common feature
• Depersonalisation (feeling a part of themselves is unreal) and derealisation (Feeling everything around is unreal) are common features in FNSD. 
• Panic disorder can be a common presentation.
• La-belle indifference: This is about being cheerful despite the diagnosis of a disability. This can be a feature of conversion and or factitious disorder.

Examination

FNSD is not a diagnosis of exclusion. There can be some positive signs of functional disorder that can be elicited here.

Common features of Conversion disorder noted

• Non- Epileptic Attack Disorder (NEAD)
• • Prolonged episode
  • Closed eyes during episode or resistance to opening
  • No injury to the tongue, No falls, No collapse
  • Crying during and after the episode
  • Ability to recall the whole incident 
  • Prolonged amnesia post-episode
• Functional limb weakness
  • Hoover’s sign positive: Involuntary extension of the “normal” leg occurs when flexing the contralateral leg against resistance. To perform the test, the examiner should hold one hand under the heel of the “normal” limb and ask the patient to flex the contralateral hip against resistance (while the patient is supine), asking the patient to keep the weak leg straight while raising it.
• Visual problems
  • Fogging test is where the individual can still read with the affected eye despite altering the lens in the normal eye
  • Tubular field vision at any distance
• Tremor Test: Tremor entrainment test is a specialised test that helps to identify unilateral tremors that are functional

Management

Non-pharmacological 

• Psychoeducation
• CBT
• Physiotherapy

Pharmacological

• Management of depression and anxiety

Differential Diagnoses

• Neurological conditions
• Somatic symptom disorder
• Factitious disorder
• Dissociative disorder
• Body dysmorphic disorder
• Depression
• Anxiety disorders
• Panic disorder

References

• MR; PJLM. Conversion disorder [Internet]. National Center for Biotechnology Information. U.S. National Library of Medicine; [cited 2022 Dec 21]. Available from: https://pubmed.ncbi.nlm.nih.gov/31855394/ 
• Bass, C. (2012). Conversion and dissociation disorders. New Oxford Textbook of Psychiatry, pp.1012–1021. doi:10.1093/med/9780199696758.003.0130. 
• Peeling, J.L. and Muzio, M.R. (2020). Conversion Disorder. [online] PubMed. Available at: https://www.ncbi.nlm.nih.gov/books/NBK551567/
• Stonnington, C.M., Barry, J.J. and Fisher, R.S. (2006). Conversion Disorder. American Journal of Psychiatry, 163(9), pp.1510–1517. doi:10.1176/ajp.2006.163.9.1510.
• Nicholson, T.R.J., Stone, J. and Kanaan, R.A.A. (2010). Conversion disorder: a problematic diagnosis. Journal of Neurology, Neurosurgery & Psychiatry, [online] 82(11), pp.1267–1273. doi:10.1136/jnnp.2008.171306.
• Owens, C. and Dein, S. (2006). Conversion disorder: the modern hysteria. Advances in Psychiatric Treatment, [online] 12(2), pp.152–157. doi:10.1192/apt.12.2.152.