DIAGNOSTIC AND PATHOPHYSIOLOGICAL ASPECTS OF PSYCHOGENIC TREMORS

Psychogenic tremor has become a rare movement disorder. Twenty-five pa tients from our movement disorder unit presented either with obviously nonorganic body shaking during stance or with extremity tremors, A su dden onset and a variable but rarely remitting course of the condition was common. The ''coactivation sign of psychogenic tremor'' and absen t finger tremor were the most consistent criteria to separate them fro m organic tremors. Quantitative analysis of tremor shows decreasing am plitudes in most organic tremors when the extremity is loaded with add itional wrights, In contrast, we found an increase of tremor amplitude for most of the cases with psychogenic tremor. This might be caused b y increased coactivation to maintain tile oscillation These clinical a nd electrophysiological features suggest a clonus mechanism induced by coactivation as the pathophysiological basis of psychogenic extremity tremor. Psychiatric evaluation did not show overt signs of hysteria f or the majority of the patients. However, we found depression and func tional somatic or psychosomatic conditions to be frequent among the pa tients. A reduced ability to cope with stressful situations may play a significant rule. The clinical course of the condition is usually far from benign. We conclude that psychogenic tremor can be positively di agnosed by means of neurologic signs in the majority of patients and i s not only a diagnosis of exclusion. The poor outcome makes early and serious neuropsychiatric attempts at therapy necessary.