Clinical Characteristics of Functional Movement Disorders: A Clinic-based Study

Functional movement disorders are recognized as a "crisis" in neurology. We aimed to determine the rate of incidence of functional movement disorder patients at a university outpatient neurology clinic in South Korea, and highlight the clinical and phenomenological characteristics.

Patients who were assessed by a movement disorders neurologist at a university hospital between March 2016 and May 2017 were screened for functional movement disorders. Demographic and clinical data were reviewed, and the phenomenology of movements was studied.

Of 321 patients evaluated for the chief complaint of a movement abnormality, approximately 10% (31 patients) were diagnosed with a functional movement disorder. The female to male ratio was 7:1 (27 females to four males). The mean age at presentation was 53 years (standard error 3.6 years), and the mean disease duration was 5 years (standard error 1.4 years). Sixty-one percent (19 out of 31 patients) had a past medical history of depression, anxiety, or other psychiatric illnesses. Tremor and speech abnormalities were most prevalent (19 and 12 patients, respectively). Onset was reported to be abrupt in 14 patients (45%). Thirteen (42%) patients were found to have improvement at a follow-up visit, 10 (32%) had no improvement, and eight (26%) were lost to follow-up.

Functional movement disorders are not uncommon in the outpatient neurology clinic. Our results confirm that tremor is the most frequent movement occurring in functional movement disorders, and the most commonly affected body parts were found to be the upper and lower extremities. Speech was also found to be frequently involved (39%). Patients with no improvement at follow-up had longer mean disease duration (6.2 years), consistent with previous observations that prolonged symptom duration is associated with poor clinical outcome. Our study results obtained from a Korean population suggest that previous observations on functional movement disorders from other regions hold true in Eastern Asia.