MIAMI—Deep brain stimulation (DBS) for dystonia may substantially improve function and quality of life for over a decade post implantation, according to patient survey results presented at the First Pan American Parkinson's Disease and Movement Disorders Congress.
The internal globus pallidus (GPI) has emerged as the optimal surgical target for the treatment of dystonia, and quality of life improvements have been documented for as long as five years on average, said Elliot Hogg, MD, of the Department of Neurology at Cedars-Sinai Medical Center in Los Angeles, and colleagues.
"No large series have consistently followed patients treated with DBS beyond five years from implantation. Whereas some studies have shown that the efficacy of stimulation improves with time, others have suggested that there may be late recurrence of dystonia," the researchers said. "Given that DBS is often performed in young patients who can be expected to have DBS for many years, and possibly decades, sustained benefit is an important clinical concern."
To study the long-term effects of GPI DBS on the quality of life of people with dystonia, Dr. Hogg and colleagues mailed the 36-Item Short Form survey (SF-36) to people with dystonia who had undergone DBS surgery at least five years prior to the study. Subjects were instructed to use the survey to compare their quality of life in the period immediately preceding DBS implantation with that of the current day. The researchers compared the scores using a matched pair t-test analysis.
Twenty-seven patients participated in the study (mean age, 38.9; 15 female). Eighteen subjects were diagnosed with a DYT1 mutation, six had other primary generalized dystonias, two had secondary dystonias, and one had cervical dystonia.
Average time from implantation was 9.5 years (range, five to 15 years). Average total SF-36 scores were 36.9 before DBS and 72.1 at current day.
Patients reported improvement across all subcategories of the SF-36, with the greatest relative improvement in social function. Patients who had had DBS for longer than 10 years (n = 10) reported similar overall improvements, compared with the population as a whole. Subjects younger than 30 (n = 11) reported higher total SF-36 improvements (ie, from 33.0 to 81.2), compared with the entire sample.
"Our study provides the longest follow-up data on DBS for dystonia at an average of 10 years since implantation," the researchers concluded. "Despite the limitations of self-reporting and possible recall bias, the results show a substantial benefit in all areas of function and quality of life, which were sustained over a decade post implantation."
Because studies have suggested that stimulation-induced parkinsonism may complicate bilateral DBS of the GPI, Dr. Hogg and colleagues also asked 27 patients who had had at least five years of DBS to complete a nine-item survey on parkinsonian symptoms. Patients reported 1.33 parkinsonian symptoms on average. The most commonly reported symptoms were hypophonia (33% of subjects) and micrographia (26%).
Both of Dr. Hogg's studies were supported in part by the Dystonia Medical Research Foundation.
—Jake Remaly
Suggested Reading
Baizabal-Carvallo JF, Jankovic J. Movement disorders induced by deep brain stimulation. Parkinsonism Relat Disord. 2016;25:1-9.
Loher TJ, Capelle HH, Kaelin-Lang A, et al. Deep brain stimulation for dystonia: outcome at long-term follow-up. J Neurol. 2008;255(6):881-884.
