NeuroTalk Support Groups - Deep Brain Stimulation for Tourette Syndrome

http://neurology.jwatch.org/cgi/cont...q=etoc_jwneuro

Quote:

Deep Brain Stimulation for Tourette Syndrome
A small open-label trial establishes safety and suggests efficacy.

This is a report of experience with deep brain stimulation (DBS) in 18 patients with severe Gilles de la Tourette syndrome that was refractory to medication and psychobehavioral therapy. The stimulation targets were the bilateral centromedian–parafascicular complex and ventral oral nuclei of the thalamus. The main assessment instrument was the Yale Global Tic Severity Rating Scale. The study was open-label except for one double-blind assessment of nine patients during "on," "off," and sham "off" periods.

Overall, the patients improved significantly on the vocal-tic, motor-tic, and social-impairment components of the scale. Improvement was greater in the "on" than the "off" parameter. Patients experienced anxiety during the sham "off" period. The procedure was generally well tolerated.

Comment: This report represents the largest published series of patients with Tourette syndrome treated with deep brain stimulation. It can be considered an early-phase study that establishes safety and suggests efficacy.

There are, as would be expected at this stage, several unresolved issues. One of the most contentious issues is the identification of the most appropriate stimulation target. Several targets for Tourette syndrome have already been examined, including the globus pallidus, the anterior limb of the internal capsule, and the nucleus accumbens. The relative attributes, risks, and benefits of these targets for Tourette are not known. Tourette is a heterogeneous disease with important comorbidities, including obsessive-compulsive components. The extent to which the clinical features in individual patients could be used as predictors of benefit with DBS must be determined.

The best choice of stimulation parameters also remains unresolved. The choice so far is empirical. There is no biologic marker to help guide the choice between high-frequency and low-frequency stimulation or between intermittent and continuous stimulation or to guide the choice of stimulation intensity. The time lag between stimulation and response and the prolonged washout effect after cessation of stimulation contribute to the complexity of optimizing stimulation parameters.

Despite these challenges, this work is an important early step in examining the circuitry of Tourette and in understanding how modulation of these neural elements can lead to behavioral changes. Because relatively few patients have been operated on so far, data and resources must be pooled and common instruments and protocols used so that these issues can begin to be addressed.

— Andres M. Lozano, MD, PhD, FRCSC

Dr. Lozano is Professor of Surgery and RR Tasker Chair in Functional Neurosurgery, University of Toronto; Senior Scientist, Toronto Western Research Institute; President, World Society for Stereotactic and Functional Neurosurgery; and Canadian Research Chair in Neuroscience (Tier 1), Toronto Western Hospital, Toronto.

Published in Journal Watch Neurology April 1, 2008

Citation(s):
Servello D et al. Deep brain stimulation in 18 patients with severe Gilles de la Tourette syndrome refractory to treatment: The surgery and stimulation. J Neurol Neurosurg Psychiatry 2008 Feb; 79:136.

Original article (Subscription may be required)
Medline abstract (Free)

Okun MS et al. Avoiding deep brain stimulation failures in Tourette syndrome. J Neurol Neurosurg Psychiatry 2008 Feb; 79:111.

Original article (Subscription may be required)
Medline abstract (Free)