Long-Term Clinical Outcome of Internal Globus Pallidus Deep Brain Stimulation for Dystonia.

BACKGROUND:GPi (Internal globus pallidus) DBS (deep brain stimulation) is recognized as a safe, reliable, reversible and adjustable treatment in patients with medically refractory dystonia. OBJECTIVES:This report describes the long-term clinical outcome of 36 patients implanted with GPi DBS at the Neurosurgery Department of Seoul National University Hospital. METHODS:Nine patients with a known genetic cause, 12 patients with acquired dystonia, and 15 patients with isolated dystonia without a known genetic cause were included. When categorized by phenomenology, 29 patients had generalized, 5 patients had segmental, and 2 patients had multifocal dystonia. Patients were assessed preoperatively and at defined follow-up examinations postoperatively, using the Burke-Fahn-Marsden dystonia rating scale (BFMDRS) for movement and functional disability assessment. The mean follow-up duration was 47 months (range, 12-84). RESULTS:The mean movement scores significantly decreased from 44.88 points preoperatively to 26.45 points at 60-month follow up (N = 19, P = 0.006). The mean disability score was also decreased over time, from 11.54 points preoperatively to 8.26 points at 60-month follow up, despite no statistical significance (N = 19, P = 0.073). When analyzed the movement and disability improvement rates at 12-month follow up point, no significant difference was noted according to etiology, disease duration, age at surgery, age of onset, and phenomenology. However, the patients with DYT-1 dystonia and isolated dystonia without a known genetic cause showed marked improvement. CONCLUSIONS:GPi DBS is a safe and efficient therapeutic method for treatment of dystonia patients to improve both movement and disability. However, this study has some limitations caused by the retrospective design with small sample size in a single-center

Overall movement and disability scales in the patients with <i>DYT</i>-1 dystonia, PKAN, and tardive dystonia.

<p>Patients with <i>DYT</i>-1 dystonia showed an abrupt decrease in motor and disability scores, and a sustained improved state during the follow-up period. Patients with <i>PKAN</i> had relatively higher motor and disability scores preoperatively. But some patients showed substantial improvement in motor score over time; 2 patients acquired improvement which appeared even after postoperative 12 months without resetting (indicated as asterisks). Tardive dystonia patients experienced no considerable improvement in motor and disability scores, except for 1 patient. (PKAN: pantothenate kinase-associated neurodegeneration)</p

The mean movement and disability scales in the patients with <i>DYT</i>-1 dystonia, PKAN, and tardive dystonia.

<p>Patients with <i>DYT</i>-1 dystonia showed abrupt decrease in movement and disability scores over time. Patients with PKAN revealed relatively higher movement and disability scores preoperatively. The mean scores of the patients with tardive dystonia remained staionary. (PKAN: pantothenate kinase-associated neurodegeneration)</p

Overall BFMDRS motor and disability scales in 6 patients who underwent 84 months follow up.

<p>Of the 6 patients who underwent 84 months follow up, one patient with tardive dystonia showed steady improvement overtime and a patient with acquired dystonia revealed constant scores over time. Except for them, remaining 4 patients with isolated dystonia without known genetic cause showed secondary worsening.</p