Most adults with functional motor disorders (FMDs) report a history of psychological or physical trauma 6 months before the onset of symptoms, a retrospective study of 482 individuals suggests. Those challenges prevent more than half of those patients – most of whom are women – from working, the researchers found.
“This finding points to the huge socioeconomical burden of FMD and emphasizes the need for better diagnostic procedure and active management,” wrote Béatrice Garcin, MD, of Sorbonne Université, Paris, and associates.
FMDs are a common presentation of functional neurologic disorders, but clinical characteristics of FMDs are not well understood because large series of consecutive patients are limited, Dr. Garcin and associates said.
In the study, published in the Journal of Psychosomatic Research, the investigators reviewed data from consecutive patients with FMD who were seen at a single hospital in France between 2008 and 2016. Half of the patients had functional motor weakness (241) and half had functional movement disorders (241). All of the patients had been referred for transcranial magnetic stimulation (TMS) as treatment for FMD.
The median age of the patients was 40 years, the median age at the onset of symptoms was 35.5 years, and 74% were women. The most common clinical presentations were tremor and dystonia (83.4%), and no demographic differences were observed between patients with functional motor weakness and functional movement disorders. Symptoms were bilateral in about half of the patients (51.7%), with left- and right-sided symptoms in 28.2% and 20.1%, respectively.
More than 80% of the patients reported a history of trauma within 6 months of the onset of their symptoms, mainly psychological trauma (50.6%). Another 20.1% reported a physical trauma, and 8.7% reported trauma from surgical procedures.
In addition, about two-thirds (66.4%) had psychiatric comorbidities; 52.7% of these were mood disorders: 49.3% depression and 3.3% bipolar disorder. “However, these results about psychiatric comorbidities should be taken with caution,” the researchers emphasized. “ and psychiatric diagnosis may lack precision because of the absence of systematic psychiatric interviews and psychiatric questionnaires in the present study.”
No significant differences appeared between the motor weakness and movement disorders groups in terms of occupation, level of education, medical somatic history, symptom onset, psychiatric comorbidities, or self-reported history of trauma. Patients in the motor weakness group were significantly younger at the time of TMS treatment and had a shorter disease duration prior to that treatment. No differences were noted between the groups with regard to clinical FMD phenotypes.
The study findings were limited by several factors, including the potential selection bias because of enrollment at a neurology referral center, lack of a control group, and underrepresentation of children and older adults, the researchers noted. Also, symptom severity was not assessed and could not be compared among phenotypes or demographic groups.
However, the results contribute to the characterization of FMD patients. “Future studies are needed to clarify the characteristics of FMD patients and the consequences of their symptoms on disability and work status,” they said.
The study received no outside funding. Lead author Dr. Garcin had no disclosures.