Long-Term Successful Outcome of Dystonic Head Tremor after Bilateral Deep Brain Stimulation of the Ventral Intermediate and Ventro-Oral Internus Nuclei: A Case Report and Literature Review of Dystonic Head Tremor

Head tremor in patients with dystonia is referred to as dystonic tremor. During surgical treatment, numerous targets may be selected, including the internal segment of the globus pallidus and the ventral intermediate (Vim) nucleus; however, there is no consensus concerning the most effective treatment target. We report herein a case of dystonic head tremor in which improvement persisted for 5 years after deep brain stimulation (DBS) of the bilateral thalamic Vim and ventro-oral internus (Voi) nuclei. The patient, a 67-year-old woman, has a horizontal head tremor associated with cervical dystonia that had been resistant to drug treatment over 3 years. Immediately following surgery, dystonia and tremor symptoms had completely improved. Voice volume declined and dysarthria occurred but improved upon adjusting the stimulation conditions. Over 5 years, both head tremor and cervical dystonia have been completely controlled, and no other obvious complications have been observed. As the Voi nucleus receives pallidothalamic projections involved in dystonia and the Vim nucleus receives cerebellothalamic projections involved in tremors, stimulating these 2 nuclei with the same electrode appears reasonable in the treatment of dystonic tremor. This case suggests that Vim-Voi DBS may be effective for treating dystonic head tremor.