Location of active contacts in patients with primary dystonia treated with globus pallidus deep brain stimulation

OBJECTIVE: Deep brain stimulation of the globus pallidus internus has been used for the treatment of various forms of dystonia, but the factors influencing postoperative outcomes remain unknown. We compared the location of the contacts being used for stimulation (active contacts) in patients with cervical dystonia, generalized dystonia, and Parkinson's disease and correlated the results with clinical outcome. METHODS: Postoperative magnetic resonance scans of 13 patients with cervical dystonia, six patients with generalized dystonia, and five patients with Parkinson's disease who underwent globus pallidus internus deep brain stimulation were analyzed. We assessed the location of the active contacts relative to the midcommisural point and in relation to the anteroposterior and mediolateral boundaries of the pallidum. Postoperative outcome was measured with the Toronto Western Spasmodic Torticollis Rating Scale (for cervical dystonia) and the Burke-Fahn-Marsden Dystonia Rating Scale (for generalized dystonia) during the last follow-up. RESULTS: We found that the location of the active contacts relative to the midcommisural point and the internal boundaries of the pallidum was similar across the groups. In our series, the contacts used for stimulation were clustered in the posterolateral region of the pallidum. Within that region, we found no correlation between the location of the contacts and postoperative outcome. CONCLUSION: The location of the active contacts used for globus pallidus internus deep brain stimulation was similar in patients with cervical dystonia, generalized dystonia, and Parkinson's disease.