Long-Term Outcomes of Deep Brain Stimulation in Pantothenate Kinase-Associated Neurodegeneration-Related Dystonia

OBJECTIVE: To investigate the long-term clinical outcomes of pallidal deep brain stimulation (GPi-DBS) in patients with pantothenate kinase-associated neurodegeneration (PKAN). METHODS: We reviewed the records of patients with genetically confirmed PKAN who received bilateral GPi-DBS for refractory dystonia and were clinically followed up for at least 2 years postoperatively at two centers in Korea. Pre- and postoperative Burke–Fahn–Marsden Dystonia Rating Scale motor subscale (BFMDRS-M) scores, disability subscale (BFMDRS-D) scores, and qualitative clinical information were prospectively collected. Descriptive analysis was performed for BFMDRS-M scores, BFMDRS-D scores, and the orofacial, axial, and limb subscores of the BFMDRS-M at 6–12, 24–36, and 60–72 months postoperatively. RESULTS: Five classic-type, four atypical-type, and one unknown-type PKAN cases were identified. The mean preoperative BFMDRS-M score was 92.1 for the classic type and 38.5 for the atypical or unknown type, with a mean BFMDRS follow-up of 50.7 months and a clinical follow-up of 69.0 months. The mean improvements in BFMDRS-M score were 11.3%, 41.3%, and 30.5% at 6–12, 24–36, and 60–72 months, respectively. In four patients with full regular evaluations until 60–72 months, improvements in the orofacial, axial, and limb subscores persisted, but the disability scores worsened from 24–36 months post-operation compared to the baseline, mainly owing to the aggravation of eating and feeding disabilities. CONCLUSION: The benefits of GPi-DBS on dystonia may persist for more than 5 years in PKAN. The effects on patients’ subjective disability may have a shorter duration despite improvements in dystonia owing to the complex manifestations of PKAN.