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Correspondence to Dr J Stone, Department of Clinical Neurosciences, Western General Hospital, Edinburgh EH4 2XU, UK; [email protected]
Introduction
Functional (or psychogenic) motor symptoms refer to weakness or movement disorders that are genuine but do not relate to an underlying neurological disease.1 2 Alternative names for this group of symptoms include motor conversion disorder/symptoms (diagnostic and statistical manual of mental disorders, fourth version (DSM IV)) and dissociative motor disorder (ICD-10). Functional motor symptoms, as we will call them in this review, are the second commonest ‘non-organic’ symptom seen in neurological practice after non-epileptic attacks,3 4 with paralysis or weakness being the commonest manifestation.3
The perception of the prognosis of functional motor symptoms in the medical literature is variable. Historically, patients with acute functional motor symptoms have often been thought to have a good outcome. However, neurologists working in specialist clinics frequently encounter patients with disabling and chronic functional motor symptoms that appear resistant to treatment.
We aimed to systematically review all follow-up studies of functional motor symptoms. We focused on global clinical outcome as well as physical and occupational functioning. We also collated data regarding negative and positive prognostic factors including comorbidity and socio-economic status.
The issue of diagnostic revision and misdiagnosis at follow-up was not included in this review since we have systematically reviewed this topic previously.5
Methods
A broad search strategy was used, using PubMed, the reference lists of articles we found in this search and reference lists of important overview articles, as well as articles known by JS, MJE and AC.
We searched for all studies reporting on functional motor symptoms, using these terms: “conversion disorder, conversion symptoms, hysteri*, somatisation, psychogenic, psychosomatic, non-organic, unexplained, dissoc*” and first “weakness, paralysis, movement disorder, gait disorder, motor symptoms, dystonia, myoclon*, tremor, twitching, wheelchair, *plegia, *paresis, disability, *” and second “prognosis”, “follow-up”, “natural history” and “natural course”. Relevant studies were identified and their reference lists were hand searched.
Inclusion and exclusion criteria are listed in table 1. We attempted to find all the literatures from 1 January 1940 up to and including 1 January 2013.
Table 1Criteria for study inclusion and exclusion
| Definition of symptoms that clearly indicates symptoms were not due to a disease process | Hysteria defined... |