Brain Stimulation Can Improve Tourette’s Syndrome
Brain Stimulation Can Improve Tourette’s Syndrome
Abstract & Commentary
Source: Babel TB, et al. Immediate and long-term outcome after infrathalamic and thalamic lesioning for intractable Tourette’s syndrome. J Neurol Neurosurg Psychiatry. 2001; 70:666-671.
Motor and vocal tics are among the most common movement disorders, affecting as many as 5 in 10,000 people. Most patients with tics do not meet criteria for Tourette’s syndrome, which requires motor and vocal tics to begin before age 21 and to be present for at least 1 year. Even among Tourette’s patients, the vast majority do not require treatment for their tics. When tics interfere with scholastic or social activities, standard medications such as clonazepam, clonidine, guanfacine, and dopamine agonists usually provide adequate tic control. Even patients with more disabling tics can often be treated successfully with dopamine-depleting agents, such as reserpine or tetrabenazine, or even neuroleptic agents. The latter should be avoided if possible because of their unacceptable risk of inducing a tardive movement disorder.
It is rare for patients with severe Tourette’s syndrome not to respond to conventional medications. These unusual patients have severe, debilitating tics that prevent them from participating in social interactions, including behaviors that may injure themselves or others. Termed "malignant Tourette’s," they present a significant therapeutic challenge, and neurosurgical approaches including limbic leucotomy, cingulotomy, and thalamic lesioning have been attempted in desperation. Because these patients are so rare, most reports of these procedures describe single cases, preventing adequate evaluation of results.
In this paper, Babel and colleagues report their experience accumulated over 3 decades with 17 patients with malignant Tourette’s treated with unilateral or bilateral thalamic surgery. They quantified the pre- and postoperative severity of motor and vocal tics by a simple scoring system. Nine patients underwent bilateral procedures, targeting the zona incerta, ventrolateral nucleus, and lamella medialis of the thalamus.
Babel et al documented a profound reduction in motor and vocal tic scores (P < 0.001). These reductions in tic severity were maintained over time (an average of 7 years). Unilateral lesioning provided adequate control of tics. Immediate postoperative complications including dystonia, dysarthria, and cerebellar deficits were common, occurring in 11 patients. These disturbances did not improve in 3 patients, and in these cases they were a source of significant disability.
Commentary
Malignant Tourette’s syndrome is one of the most challenging hyperkinetic movement disorders. In the United States, few neurosurgical operations have been performed in these patients. This paper is of interest for several reasons. First, it documents that ablation of specific thalamic nuclei can improve motor and vocal tics, and that these effects can be long lasting. Second, it is not surprising that there was a high incidence of adverse events, and that a significant minority of these events were disabling. Many of the surgeries were performed prior to the availability of high-resolution magnetic resonance imaging, and it is now known that bilateral lesioning procedures have an unacceptable incidence of side effects of dysarthria and cognitive impairment.
In the future, most stereotactic surgeries will use deep brain stimulation instead of lesioning procedures. Deep brain stimulation is safer and also offers the opportunity to finetune stimulation parameters to obtain maximum benefit. Given the encouraging nature of Babel et al’s results, a trial of deep brain stimulation of the thalamus for malignant Tourette’s would appear warranted. —Steven Frucht
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