Directional deep brain stimulation for cervical dystonia: Outcomes, challenges and future directions

<h2>Abstract</h2><h3>Background</h3> Cervical dystonia is a movement disorder marked by involuntary head and neck muscle contractions. Deep brain stimulation (DBS) targeting the globus pallidus internus (GPi) is a recognised treatment, with directional DBS—enabling current steering—gaining traction in movement disorder management. <h3>Objective</h3> This study assessed clinical outcomes in cervical dystonia patients treated with directional DBS at our centre, compared to a matched group receiving conventional DBS, and examined challenges and research directions in directional DBS for dystonia. <h3>Methods</h3> Eleven patients with adult-onset isolated cervical dystonia received bilateral GPi stimulation with directional DBS systems, compared to a demographically matched cohort with conventional systems. Clinical outcomes and stimulation parameters were recorded at the latest follow-up, and electrode positioning was analysed using patient-specific volumes of tissue activated (VTA). <h3>Results</h3> Directional DBS significantly improved dystonia severity, pain, disability, and quality of life (p < 0.001), with no significant differences versus conventional DBS. Five patients utilised at least one directional electrode; six were set to bilateral "ring-mode" stimulation. Group VTA for directional DBS was positioned more medial and anterior than ring-mode or conventional DBS. Side effects were less frequent in directional DBS (20 %) than in ring-mode (83 %) or conventional DBS (36 %). <h3>Conclusion</h3> Directional DBS showed efficacy comparable to conventional DBS in managing cervical dystonia, with fewer side effects. Despite these benefits, its application in dystonia remains limited compared to other movement disorders, such as Parkinson's disease and essential tremor, though advances in image-guided programming and biomarker discovery could support wider use in dystonia management.