PSYCHOGENIC MYOCLONUS

We report 18 patients (13 women, 5 men; age range, 22 to 75 years; mean, 42.5), whom we ultimately diagnosed as having ''psychogenic myoclonus.'' The myoclonus was present for an average of 36 months (range, 1 to 110), and it was segmental in 10, generalized in seven, and focal in one. Stress precipitated or exacerbated the myoclonic movements in 15 patients; 14 had a definite increase in myoclonic activity during periods of anxiety. A combination of the following findings helped to establish the psychogenic nature of the myoclonus: (1) clinical features incongruous with ''organic'' myoclonus, (2) evidence of underlying psychopathology, (3) an improvement with distraction in 14 and with placebo in nine, and (4) the presence of incongruous sensory loss or false weakness in five. Over half of all patients with adequate follow-up improved after gaining insight into the psychogenic mechanisms of their movement disorder. This study attempts to characterize psychogenic myoclonus, the most common psychogenic movement disorder in our movement disorders clinic, and provides a guide to its diagnosis and treatment.