Thalamus Stimulation for Myoclonus-Dystonia Syndrome: Five Cases and Long-term Follow-up.

BACKGROUND: Myoclonic dystonia syndrome (MDS) is a rare inherited movement disorder characterized by the coexistence of myoclonic jerks and dystonia. Deep brain stimulation (DBS) is a promising treatment for patients with MDS that targets the globus pallidus internus or ventral intermediate nucleus (Vim) of the thalamus. However, there are few studies regarding the long-term effects of Vim DBS in patients with MDS and even fewer in those without gene mutations. METHODS: Two positive and three negative SGCE mutation patients presenting with predominant myoclonus underwent Vim DBS. The Unified Myoclonus Rating Scale and the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) were assessed pre- and postoperation. RESULTS: Over an average follow-up period of 50 months, the myoclonus improvement rate was 92.7%. The average improvement in the BFMDRS motor score was 71.4% and the average improvement in the BFMDRS disabling score was 75.8%. CONCLUSIONS: This study suggests that Vim DBS can be a safe and effective treatment option for patients with MDS. Vim DBS alone may be preferable for patients with myoclonus-dominated MDS regardless of the identification of an SGCE mutation. Additional globus pallidus internus DBS may be used for progressive dystonia after Vim DBS.