A POSITRON EMISSION TOMOGRAPHY STUDY OF CEREBRAL ACTIVATION-ASSOCIATED WITH ESSENTIAL AND WRITING TREMOR

Objective: To compare the abnormal patterns of cerebral activation ass ociated with essential and writing tremors. Design: Positron emission tomography using oxygen 15-labeled water was utilized to determine reg ional cerebral blood flow. Positron emission tomography images that we re taken of the brain in individual patients were coregistered with ma gnetic resonance images of the same brain to ascertain accurate locali zation of cerebral activation in single patients. Patients with essent ial tremor underwent scanning at rest, during involuntary postural tre mor, and during passive wrist oscillation. Normal control subjects und erwent scanning at rest and during voluntary and passive wrist oscilla tion. Patients with writing tremor underwent scanning while they were holding a pen to paper with consequent involuntary tremor and again wh ile they were holding a pen in the same supinated arm without tremor. Setting: Research hospital. Patients or Other Participants: Seven pati ents with essential tremor, six patients with writing tremor, and six matched control subjects. Interventions: None. Main Outcome Measures: Regional cerebral blood flow. Results: Essential tremor was associated with abnormal bilateral cerebellar, red nuclear, and thalamic activat ion. Writing tremor was also associated with abnormal bilateral cerebe llar activation. Voluntary wrist oscillation in control subjects cause d only ipsilateral cerebellar activation. These findings were evident in single patients, when positron emission tomography images were core gistered with magnetic resonance images and on group analysis of the p ooled positron emission tomography data after transformation into ster eotaxic space. Conclusion: These results indicate that both essential and writing tremors are associated with abnormal bilateral overactivit y of cerebellar connections.