Different clinical course of pallidal deep brain stimulation for phasic- and tonic-type cervical dystonia

Dystonia has been treated well using deep brain stimulation at the globus pallidus internus (GPi DBS). Dystonia can be categorized as two basic types of movement, phasic-type and tonic-type. Cervical dystonia is the most common type of focal dystonia, and sequential differences in clinical outcomes between phasic-type and tonic-type cervical dystonia have not been reported. This study included a retrospective cohort of 30 patients with primary cervical dystonia who underwent GPi DBS. Age, disease duration, dystonia direction, movement types, employment status, relevant life events, and neuropsychological examinations were analyzed with respect to clinical outcomes following GPi DBS. The only significant factor affecting clinical outcomes was movement type (phasic or tonic). Sequential changes in clinical outcomes showed significant differences between phasic- and tonic-type cervical dystonia. A delayed benefit was found in both phasic- and tonic-type dystonia. The clinical outcome of phasic-type cervical dystonia is more favorable than that of tonic-type cervical dystonia following GPi DBS.