Long-Term Efficacy of Deep Brain Stimulation of Bilateral Globus Pallidus Internus in Primary Meige Syndrome.

[OBJECTIVE] Deep brain stimulation (DBS) of the internal segment of the globus pallidus (GPi) is an alternative therapy in ameliorating the clinical symptoms of primary Meige syndrome. Nevertheless, proof of its efficacy and safety is insufficient due to several case reports and small-sample clinical studies. This study aims to investigate postoperative long-term efficacy in patients undergoing DBS of the GPi for primary Meige syndrome.

[METHODS] We performed a retrospective study to assess the efficacy and safety of bilateral GPi stimulation in 40 patients with primary Meige syndrome who responded poorly to medical treatments or botulinum toxin injections. All participants were postoperatively followed up at the outpatient clinic, and their motor functions were assessed using the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS). The severity of patients' dystonia was evaluated before surgery and at follow-up neurostimu-lation.

[RESULTS] The implanted stimulator was turned on 1 month after surgery. All 40 patients received monopolar stimulation using the following parameters: voltage 2.5-3.5 V (average: 2.6 ± 0.8 V), frequency 60-160 Hz (average: 88.0 ± 21.3 Hz), and pulse width 60-185 μS (average: 90.0 ± 21.1 μS). In 28 of 40 patients, the symptoms had signifi-cantly improved within 1 week of stimulation. Most of the patients had been followed up for 6-24 months (average: 15.0 ± 7.8 months). The clinical symptoms of all patients had significantly improved. At 6, 12, and 24 months after surgery, the BFMDRS subscores of eyes, mouth, speech, and swallowing were significantly lower, and subscores of mouth movement showed progressively decreased with prolonged stimulation time. The overall improvement rate was 83%. Five adverse events occurred in the 40 patients; all of these events resolved without permanent sequelae.

[CONCLUSIONS] Bilateral GPi-DBS demonstrated satisfactory long-term efficacy in the treatment of primary Meige syndrome and could serve as an effective and safe option.