Alternative Deep Brain Stimulation Targets in the Treatment of Isolated Dystonic Syndromes: A Multicenter Experience-Based Survey.

Background: The globus pallidus internus (GPi) is the traditional evidence-based deep brain stimulation (DBS) target for treating dystonia. Although patients with isolated "primary" dystonia respond best to GPi-DBS, some are primary or secondary nonresponders (improvement <25%), showing variability in clinical response.

Objective: The aim was to survey current practices regarding alternative DBS targets for isolated dystonia patients with focus on nonresponders to GPi-DBS.

Methods: A 42-question survey was emailed and distributed during a DBS conference to clinicians involved in DBS for dystonia. The survey covered (1) use of alternative DBS targets as primary or rescue options, (2) target selection based on dystonia phenomenology, (3) experience with secondary nonresponders to GPi-DBS, and (4) management of patients with additional DBS leads.

Results: The response rate was 53.8%, including neurologists and neurosurgeons from 28 DBS centers in 13 countries; 89% of neurologists and 86% of neurosurgeons used alternative DBS targets to GPi, with subthalamic nucleus being the most common initial or rescue alternative to GPi. Patients with additional tremor received DBS in the ventral intermediate nucleus or caudal zona incerta. Individual experience ranged from 5 to 25 patients. Most patients were still receiving dual target stimulation at the last follow-up.

Conclusions: We show that more than 85% of surveyed clinicians use alternative DBS targets, mostly in some isolated dystonia patients not adequately responsive to GPi-DBS. More knowledge is needed to evaluate outcomes in alternative targets and establish the best strategies for managing insufficient GPi-DBS response in dystonia patients with diverse phenomenology. Our article contributes to establishing a clearer time frame and criteria for defining nonresponders in dystonia patients undergoing DBS.