Deep Brain Stimulation Effective in Dystonia

Low-frequency deep brain simulation (DBS) of the internal globus pallidus internus (GPi) in young patients with primary torsion dystonia (PTD) is as effective as more conventional high frequency DBS, claims a new study.

Researchers at Mount Sinai Medical Center (New York, NY, USA) retrospectively evaluated the efficacy of lower frequency DBS at 60 Hz in 15 consecutive patients with medically refractory PMD. The mean age of the patients was 20 years, and 12 of the 15 patients had the DYT1 gene mutation. The patients had DBS leads stereotactically implanted within the GPi. The researchers analyzed magnetic resonance imaging (MRI) and intraoperative microelectrode recordings and assessed function on the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) at baseline and at 1, 3, 6, and 12 months after implantation.

The results showed that all patients tolerated implantation well. All showed progressive improvement of their BFMDRS motor subscores, with a mean 38% improvement in the median score at one month and 89% improvement at one year. The disability subscores showed similar improvements. The study was published in the August 14, 2007, issue of the journal Neurology.

"The clinical response to DBS allowed seven patients to completely discontinue their medications,” said lead author Dr. Michele Tagliati, an associate professor in the department of neurology. "Six additional patients had reduced their medications by at least 50%. Surgical complications were limited to two superficial infections, which were treated successfully.”

PTD is a neurologic movement disorder characterized by involuntary muscle contractions, which force certain parts of the body into abnormal and painful movements or postures. Dystonia can affect any part of the body including the arms and legs, trunk, neck, eyelids, face, or vocal cords. The causes of most types of dystonia are still not completely understood. Several types, including DYT1+, RDP, and Dopa-Responsive, are genetically caused; other types, called tardive dystonia, are cased by known reactions to multiple medications, while what is called secondary generalized dystonia appear to also be genetically linked.


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