The prognosis of functional (psychogenic) motor symptoms: a systematic review

The prognosis of functional (or psychogenic) motor symptoms (weakness and movement disorder) has not been systematically reviewed.

We systematically reviewed PubMed for all studies of eight or more patients with functional motor symptoms reporting follow-up data longer than 6 months (excluding studies reporting specific treatments). We recorded symptom duration, physical and psychiatric comorbidity, disability, occupational functioning at follow-up and prognostic factors.

24 studies were included. There was heterogeneity regarding study size (number of patients (n)=10 491), follow-up duration clinical setting and data availability. Most studies (n=15) were retrospective. Reported symptom outcome was highly variable. Mean weighted follow-up duration was 7.4 years (in 13 studies where data was extractable). The mean percentage of patients same or worse at follow-up for all studies was 39%, range 10% to 90%, n=1134. Levels of physical disability and psychological comorbidity at follow-up were high. Short duration of symptoms, early diagnosis and high satisfaction with care predicted positive outcome in two studies. Gender had no effect. Delayed diagnosis and personality disorder were negatively correlated with outcome. Prognostic factors that varied between studies included age, comorbid anxiety and depression, IQ, educational status, marital status and pending litigation.

Existing follow-up studies of functional motor symptoms give us some insights regarding outcome and prognostic factors but are limited by their largely retrospective and selective nature. Overall, prognosis appears unfavourable. The severity and chronicity of functional motor symptoms argues for larger prospective studies including multiple prognostic factors at baseline in order to better understand their natural history.