Deep Brain Stimulation of the Thalamic Ventral Lateral Anterior Nucleus for DYT6 Dystonia

Background: A missense mutation of the THAP1 gene results in DYT6 primary dystonia. While deep brain stimulation (DBS) of the internal globus pallidus (GPi) is effective in treating primary dystonia, recent reports indicate that GPi DBS is only mildly effective for DYT6 dystonia. Objective: To describe a patient with DYT6 dystonia who underwent thalamic ventral lateral anterior (VLa) nucleus DBS. Patient: A 35-year-old Japanese man had been experiencing upper limb dystonia and spasmodic dysphonia since the age of 15. His dystonic symptoms progressed to generalized dystonia. He was diagnosed as having DYT6 dystonia with mutations in the THAP1 gene. Because his dystonic symptoms were refractory to pharmacotherapy and pallidal DBS, he underwent thalamic VLa DBS. Results: Continuous bilateral VLa stimulation with optimal parameter settings ameliorated the patient's dystonic symptoms. At the 2-year follow-up, his Burke-Fahn-Marsden Dystonia Rating Scale total score decreased from 71 to 11, an improvement of more than 80%. Conclusions: The thalamic VLa nucleus could serve as an alternative target in DBS therapy for DYT6 dystonia.