Functional neurological and somatic symptom disorders

Functional neurological disorder (previously termed conversion disorder) and somatic symptom disorder are both characterised by somatic symptoms associated with significant distress or impairment.

The underlying cause is not fully understood. Although psychological stressors can be important risk factors and may perpetuate symptoms, they are not necessary to make the diagnosis.

Functional neurological disorder can be diagnosed on the basis of positive 'rule in' features on neurological examination - it is no longer considered a diagnosis of exclusion.

Good therapeutic alliance, validation of the patient's suffering, and shared clinician-patient understanding of the condition are essential for effective management.

Treatment includes cognitive behavioural therapy, physiotherapy, and avoiding unnecessary medicines, tests, and procedures. Diagnosis and treatment of associated comorbid psychiatric conditions can benefit overall functioning and recovery.

This topic describes diagnosis and management of functional neurological disorder and somatic symptom disorder in adults only; diagnosis and management in children is beyond its scope.

Functional neurological disorder (previously termed conversion disorder) and somatic symptom disorder are (neuro)psychiatric conditions that fall under the somatic symptom and related disorders category of the Diagnostic and Statistical Manual of Mental Disorders, 5th edition, text revision (DSM-5-TR) (previously termed somatoform disorders). Somatic symptom and related disorders are those with prominent physical symptoms associated with significant distress and impairment of function.

Functional neurological disorder is characterised by motor or sensory function deficits that suggest neurological or medical conditions associated with characteristic 'rule in' features on neurological examination and clinically significant distress or social/occupational impairment. Somatic symptom disorder is characterised by one or more somatic symptoms that are distressing or result in significant disruption of daily life. To meet DSM-5-TR criteria, these patients must have excessive thoughts, feelings, or behaviours related to the somatic symptoms or associated health concerns as manifested by at least one of the following: disproportionate and persistent thoughts about the seriousness of one’s symptoms; persistently high levels of anxiety about health or symptoms; excessive time or energy devoted to these symptoms or health concerns. Importantly, even if any one somatic symptom is not continuously present, the state of being symptomatic is persistent (typically more than 6 months).