Safety and efficacy of unilateral and bilateral pallidotomy for primary dystonia.

OBJECTIVE: Ablation of the globus pallidus internus (pallidotomy) is an effective surgical intervention for dystonia. However, the current literature on the efficacy and safety of pallidotomy for dystonia is derived only from single-case reports and small cohort studies. METHODS: We retrospectively analyzed patients with primary dystonia who underwent pallidotomy at our institution between 2014 and 2019. Neurological conditions were evaluated using the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS, range: 0-120). We evaluated the total BFMDRS score and each subitem score (nine body regions) in the patients who underwent unilateral and bilateral pallidotomy before surgery and at last available follow-up. Moreover, postoperative complications were analyzed. RESULTS: We found that 69 and 20 patients underwent unilateral and bilateral pallidotomy respectively. The mean age at dystonia onset was 40.4 ± 15.2 years. The mean clinical follow-up period was 17.2 ± 11.6 months. Unilateral pallidotomy significantly improved the total BFMDRS score from 11.2 ± 14.7 preoperatively to 5.4 ± 7.6 at last available follow-up (51.8% improvement, p < 0.001). Furthermore, there was a significant and independent improvement in all midline BFMDRS subitems, including eyes, mouth, speech/swallow, and neck, after unilateral pallidotomy. Bilateral pallidotomy significantly improved the total BFMDRS score from 14.6 ± 10.2 preoperatively to 3.8 ± 8.2 at last available follow-up (74.0% improvement, p < 0.001). However, bilateral pallidotomy induced medically refractory parkinsonism (postural instability and gait disturbance) in five patients, dysarthria in three patients, and dysphagia in one patient. INTERPRETATION: Unilateral radiofrequency pallidotomy remains a viable treatment option for patients with some forms of dystonia. Bilateral pallidotomy cannot be recommended due to unacceptably high complication rates.

Pallidotomy for severe tardive jaw-opening dystonia.

Bilateral pallidotomy was performed in a schizophrenic patient with severe jaw-opening dystonia developed after chronic neuroleptic treatment. The dystonia led to sustained mandibular joint dislocation, and tracheotomy was performed after suffocation. The jaw-opening dystonia disappeared immediately following pallidotomy; the tracheotomy was closed, and he regained eating and speech ability. Analysis of the neuronal firing of the globus pallidus revealed low neuronal firing rates in the internal pallidum (GPi) and an irregular burst pattern of the GPi cells compared to those in Parkinson's disease. These results suggest that pallidotomy is a treatment option for tardive jaw-opening dystonia and that dystonia of this type is driven by abnormal neural activities in the GPi.

Long-term suppression of tremor by deep brain stimulation of the ventral intermediate nucleus of the thalamus combined with pallidotomy in hemiparkinsonian patients.

Deep brain stimulation (DBS) of the ventral intermediate nucleus of the thalamus (VIM) is a powerful surgical option in the treatment of tremor-predominant Parkinson's disease. However, its therapeutic efficacy depends on the tremor distribution. DBS is highly efficient in relief of distal appendicular tremor but not other types of tremor. Also, it is generally thought that DBS of the VIM has no significant beneficial effects on other motor symptoms of Parkinson's disease. We report two hemiparkinsonian patients, in whom unilateral VIM DBS combined with posteroventral pallidotomy produced long-lasting suppression of not only hand tremor, but also leg or jaw tremor and other motor symptoms.