[Rhythmical myoclonus and tremor at rest disclosing mesencephalic metastasis]

We report a case in which rhythmical myoclonus and tremor at rest revealed a thalamo-subthalamic metastasis from a bronchial carcinoma. Tremor of the upper limbs and face (4 Hz) disappeared with sustained posture and action. A cogwheel phenomenon, hypotonia and disorders of automatic and voluntary movements were also present. Surface electromyographic recordings showed a rhythmical, synchronous activity of the biceps brachialis and triceps muscles at rest. Pathology disclosed lesions of the red nucleus and neighbouring area and severe compression of the substantia nigra which were likely to be the cause of the signs and symptoms.