Delayed-onset cerebellar syndrome

Background: Delayed-onset involuntary movements, including dystonia and myoclonus, have been reported after stroke or head trauma. Moreover, there have been reports of delayed-onset isolated intention tremor and, in several of these cases, gait ataxia. Objective: To further define the clinical features of a delayed-onset cerebellar syndrome. Design: Subjects with cerebellar tremor and either head trauma or stroke were identified using a computerized database, providing detailed demographic and clinical information on 4002 patients with involuntary movements other than Parkinson's disease seen at our center between 1983 and 1995. Medical records and videotaped neurological examinations were retrospectively reviewed. Setting: The Center for Parkinson's Disease and Other Movement Disorders at Columbia-Presbyterian Medical Center, New York, NY. Patients: Five patients with delayed onset cerebellar syndromes. Results: Five patients with stroke or head trauma developed a cerebellar syndrome 3 weeks to 2 years after the initial insult. The syndrome, characterized by intention tremor, ataxic dysarthria, nystagmus, dysmetria, dysdiadochokinesis, and gait ataxia, was progressive in at least one patient. In four patients, lesions were present on neuroimaging in the thalamus or brain stem (especially in the midbrain). Conclusions: A delayed-onset cerebellar syndrome may follow head trauma or stroke. The syndrome is sometimes progressive and often disabling. The delayed onset implies that the syndrome is not caused by the initial lesion itself but may be caused by the development of postsynaptic supersensitivity or secondary reorganization of involved pathways.