[Dystonia and tremor in bilateral lesion of the posterior mesencephalon and the vermis].

The aim of this study is to report the association of diffuse dystonia and tremor in a bilateral and extended lesion of the posterior mesencephalon. After surgery on a meningioma of the upper part of the fourth ventricle, this patient presented with facial dystonia, predominating on orbicularis muscles and peribuccal area, and limb dystonia, with tonic extension of fingers and first toes. The tremor was associated with a rhythmic and most often alternate agonist-antagonist muscular activation, whose frequency varied from 3 to 7 Hz. These disorders were increased by the standing position, voluntary movement, somatosensory stimulations, stress or emotion. Pyramidal and somatosensory tracts were spared. Therapeutic trials showed that both the dystonia and tremor were improved by subcutaneous injection of apomorphine, the dystonia by trihexyphenidyle, and the tremor by carbamazepine and propranolol, but not by levodopa and benserazide. The cerebral blood flow study using HMPAO showed a relatively important activity on the cerebellum, which could play a role in the onset of these disorders.