Functional weakness: clues to mechanism from the nature of onset.
Jon Stone, Charles Warlow, Michael Sharpe
Journal of Neurology, Neurosurgery, and Psychiatry January 2012 DOI: 10.1136/jnnp-2011-300125 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Retrospective interview study Peer reviewed |
|---|---|
| Sample size | 107 |
| Population | Adults with functional weakness of less than 2 years' duration |
| Key points | Functional weakness most commonly begins suddenly (46% of patients), with panic, dissociative symptoms, or injury to the affected limb frequently reported at onset; 13% were present on waking or after general anaesthesia and 39% developed gradually. In 16% of patients no potentially relevant factors were identified. The authors propose that symptoms and circumstances at onset can suggest mechanisms of symptom formation in vulnerable individuals. |
Abstract
Functional weakness describes weakness which is inconsistent and incongruent with disease. It is also referred to as motor conversion disorder (DSM-IV), dissociative motor disorder (ICD-10) and 'psychogenic' paralysis. Studies of aetiology have focused on risk factors such as childhood adversity and life events; information on the nature and circumstance of symptom onset may shed light on the mechanism of symptom formation. To describe the mode of onset, associated symptoms and circumstances at the onset of functional weakness. Retrospective interviews administered to 107 adults with functional weakness of <2 years' duration. The sample was 79% female, mean age 39 years and median duration of weakness 9 months. Three distinct modes of onset were discerned. These were: sudden (n=49, 46%), present on waking (or from general anaesthesia) (n=16, 13%) or gradual (n=42, 39%). In 'sudden onset' cases, panic (n=29, 59%), dissociative symptoms (n=19, 39%) and injury to the relevant limb (n=10, 20%) were commonly associated with onset. Other associated symptoms were non-epileptic attacks, migraine, fatigue and sleep paralysis. In six patients the weakness was noticed first by a health professional. In 16% of all patients, no potentially relevant factors could be discerned. The onset of functional weakness is commonly sudden. Examining symptoms and circumstances associated closely with the onset suggests hypotheses for the mechanism of onset of weakness in vulnerable individuals.