Single-unit activity of the anterior Globus pallidus internus in Tourette patients and posterior Globus pallidus internus in dystonic patients.

OBJECTIVES: Our goal was to provide a detailed analysis of neurons' electrophysiological activity recorded in sub-territories of Globus pallidus internus (GPi) used as Deep Brain Stimulation (DBS) targets for these clinical conditions to potentially assist electrode targeting. METHODS: We used intra-operative microelectrode recording during stereotactic neurosurgery to guide implantation of DBS lead. RESULTS: Units in the medial anterior part of GPi of 7 Tourette's syndrome patients under general anesthesia were firing at mean and median rate of 32.1 and 21 Hz respectively (n = 101), with 45% of spikes fired during bursts and 21.3 bursts per minute. In the latero-posterior part of GPi of 7 dystonic patients under local anesthesia the mean and median activity were 46.1 and 30.6 Hz respectively (n = 27), and a mean of 21.7 bursts per minute was observed, with 30% of all spikes occurring during these bursts. CONCLUSION: Units activity pattern - slow-regular, fast-irregular or fast-regular were present in different proportions between the two targets. SIGNIFICANCE: The electrophysiological characteristics of the medial-anterior part of GPi and its latero-posterior portion can be used to assist DBS electrode targeting and also support the refinement of pathophysiological models of Tourette's syndrome and Dystonia.

Deep brain stimulation of the antero-medial globus pallidus interna for Tourette syndrome.

BACKGROUND: We have previously reported the results of Deep Brain Stimulation (DBS) of the antero-medial globus pallidus interna (GPi) for severe Tourette Syndrome (TS) in 11 patients. We extend this case series to 17 patients and a longer follow-up to a maximum of 46 months. METHODS: 17 patients (14 male; mean age 29.1 years, range 17-51 years) with severe and medically intractable TS were implanted with Medtronic quadripolar electrodes bilaterally in the antero-medial GPi. The primary outcome measure was the Yale Global Tic Severity Scale (YGTSS). Secondary outcome measures included the Yale-Brown Obsessive Compulsive Scale, Hamilton Depression Rating Scale, Gilles de la Tourette Quality of Life Scale and Global Assessment of Functioning. Follow up was at one month, three months and finally at a mean 24.1 months (range 8-46 months) following surgery. RESULTS: Overall, there was a 48.3% reduction in motor tics and a 41.3% reduction in phonic tics at one month, and this improvement was maintained at final follow-up. 12 out of 17 (70.6%) patients had a>50% reduction in YGTSS score at final follow up. Only 8 patients required ongoing pharmacotherapy for tics post-surgery. Patients improved significantly on all secondary measures. Adverse consequences included lead breakage in 4 patients, infection (1), transient anxiety (2), dizziness (1), poor balance (1) and worsening of stuttering (1). CONCLUSIONS: This case series provides further support that antero-medial GPi DBS is an effective and well tolerated treatment for a subgroup of severe TS, with benefits sustained up to 4 years.

Deep brain stimulation of anteromedial globus pallidus interna for severe Tourette's syndrome.

OBJECTIVE: Multiple anatomical targets for deep brain stimulation (DBS) have been proposed for the treatment of severe Tourette's syndrome. In this open study, the authors evaluated the effectiveness of DBS of the anteromedial globus pallidus interna on tic severity and common comorbidities. METHOD: Eleven patients (eight of them men, mean age=39 years) with severe and medically intractable Tourette's syndrome underwent implantation of Medtronic quadripolar electrodes in the globus pallidus interna bilaterally. The primary outcome measure was the Yale Global Tic Severity Scale. Secondary outcome measures included the Yale-Brown Obsessive Compulsive Scale, the Hamilton Depression Rating Scale, the Gilles de la Tourette Syndrome-Quality of Life Scale, and the Global Assessment of Functioning Scale. Follow-up occurred at 1 month and then at a mean of 14 months after surgery (range=4-30 months). RESULTS: Ten patients (91%) reported improvement in tic severity soon after DBS. Overall, there was a 48% reduction in motor tics and a 56.5% reduction in phonic tics at final follow-up. Six patients (54.5%) had a more than 50% reduction, sustained for at least 3 months, in Yale Global Tic Severity Scale score. Only two patients required ongoing pharmacotherapy for tics after surgery, and patients improved significantly on all secondary measures. One patient did not tolerate DBS and discontinued treatment after 3 months. Greater anxiety in two patients and hardware malfunction in three patients were noteworthy adverse outcomes. CONCLUSIONS: The results suggest anteromedial globus pallidus interna DBS for Tourette's syndrome is an effective and well-tolerated treatment for a subgroup of patients with severe Tourette's syndrome.