Deep brain stimulation (DBS) showed promise in improving tic severity in patients with Tourette syndrome in a prospective, open-label registry study, but the treatment was associated with adverse events in a substantial number of patients.
“The first-year results of this multinational electronic collaboration strengthen the notion that DBS could be a potential surgical treatment for select patients with Tourette syndrome,” Daniel Martinez-Ramirez, MD, of the University of Florida, Gainesville, and his colleagues wrote in their study published online Jan. 16 in JAMA Neurology. “Practitioners should be aware of the high number of stimulation-related adverse events and that these are likely reversible.”
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The research team studied data from 185 patients with bilateral Tourette syndrome in 10 countries who had undergone DBS implantation between Jan. 1, 2012, and Dec. 31, 2016, and found that DBS significantly improved the Yale Global Tic Severity Scale scores of patients in the study for both motor and phonic tics. Mean motor tic scores improved 38.2% at 6 months, compared with baseline, and 38.5% at 12 months. A similar effect was observed for phonic tic scores, with improvements of 44.2% and 42.7% at 6 and 12 months, compared with baseline, respectively. While there was slight variation between the 6- and 12-month follow-ups for both phonic and motor tic scores, these changes were not statistically significant.
Despite the improvement of Yale Global Tic Severity Scale scores, adverse events were prevalent among patients in the study. Of 158 patients, 56 (35.4%) reported a total of 160 adverse events during the first follow-up year. Of those events reported, 48 (30.8%) were stimulation related, while 6 (3.8%) were surgically related, and 2 (1.3%) were related to issues with the device. The most common adverse events were dysarthria, reported by 10 patients (6.3%), and paresthesias, reported by 13 patients (8.2%). These events were not permanent and did not involve any major complications.
There are a number of limitations when using data from a multinational registry and database, according to the authors. Using information from different sites may affect results because surgical and treatment techniques may differ by location. Additionally, the lack of standardized inclusion criteria for the registry may have affected the results.
Despite the study’s limitations and the adverse events were observed, DBS still appeared effective in improving motor and phonic tics in Tourette syndrome patients. With these results, Dr. Martinez-Ramirez and his associates recommended what needs to be done to further research into DBS.
“Larger numbers of patients will need to receive DBS implants across multiple targets, and comparison of center-to-center outcomes could help refine the therapy,” they wrote. “Publishing multiyear outcomes to a public website (https://tourettedeepbrainstimulationregistry.ese.ufhealth.org) will improve access to information, improve data sharing, and, we hope, contribute to improvement in outcomes.”
Two investigators reported receiving grants from various pharmaceutical companies, government agencies, and foundations. Both also served as consultants to major pharmaceutical companies. All other researchers had no relevant financial conflicts to disclose.
SOURCE: Martinez-Ramirez D et al. JAMA Neurol. 2018 Jan 16. doi: 10.1001/jamaneurol.2017.4317.