CLINICAL ARTICLE ABBREVIATIONS BFMDRS = Burke-Fahn-Marsden Dystonia Rating Scale; CD = cervical dystonia; CI = confidence interval; CP = cerebral palsy; DBS = deep brain stim- ulation; GPi = globus pallidus pars internus; ICL = intercommissural line; iMRI = intraoperative MRI; IPG = internal pulse generator; MCP = midcommissural point; MER = microelectrode recording; PD = Parkinson disease; QSM = quantitative susceptibility mapping; SAE = serious adverse event; SEM = standard error of the mean; STN = subthalamic nucleus; TWSTRS = Toronto Western Spasmodic Torticollis Rating Scale. SUBMITTED March 2, 2019. ACCEPTED June 27, 2019. INCLUDE WHEN CITING Published online October 11, 2019; DOI: 10.3171/2019.6.JNS19548. * V.D.S. and Y.B.B. contributed equally to this work. Clinical outcomes of pallidal deep brain stimulation for dystonia implanted using intraoperative MRI *Vibhash D. Sharma, MD, 1,2 Yarema B. Bezchlibnyk, MD, PhD, 3,4 Faical Isbaine, PhD, 3 Kushal B. Naik, MBBS, MPH, 6 Jennifer Cheng, MD, 3,5 John T. Gale, PhD, 3 Svjetlana Miocinovic, MD, PhD, 1 Cathrin Buetefsch, MD, PhD, 1 Stewart A. Factor, DO, 1 Jon T. Willie, MD, PhD, 1,3 Nicholas M. Boulis, MD, 3 Thomas Wichmann, MD, 1 Mahlon R. DeLong, MD, 1 and Robert E. Gross, MD, PhD 1,3 Departments of 1 Neurology and 3 Neurosurgery, Emory University School of Medicine, Atlanta, Georgia; Departments of 2 Neurology and 5 Neurosurgery, University of Kansas Medical Center, Kansas City, Kansas; 4 Department of Neurosurgery and Brain Repair, University of South Florida, Tampa, Florida; and 6 Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, Georgia OBJECTIVE Lead placement for deep brain stimulation (DBS) using intraoperative MRI (iMRI) relies solely on real-time intraoperative neuroimaging to guide electrode placement, without microelectrode recording (MER) or electrical stimula- tion. There is limited information, however, on outcomes after iMRI-guided DBS for dystonia. The authors evaluated clini- cal outcomes and targeting accuracy in patients with dystonia who underwent lead placement using an iMRI targeting platform. METHODS Patients with dystonia undergoing iMRI-guided lead placement in the globus pallidus pars internus (GPi) were identifed. Patients with a prior ablative or MER-guided procedure were excluded from clinical outcomes analysis. Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) scores and Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) scores were assessed preoperatively and at 6 and 12 months postoperatively. Other measures analyzed include lead accuracy, complications/adverse events, and stimulation parameters. RESULTS A total of 60 leads were implanted in 30 patients. Stereotactic lead accuracy in the axial plane was 0.93 ± 0.12 mm from the intended target. Nineteen patients (idiopathic focal, n = 7; idiopathic segmental, n = 5; DYT1, n = 1; tardive, n = 2; other secondary, n = 4) were included in clinical outcomes analysis. The mean improvement in BFM- DRS score was 51.9% ± 9.7% at 6 months and 63.4% ± 8.0% at 1 year. TWSTRS scores in patients with predominant cervical dystonia (n = 13) improved by 53.3% ± 10.5% at 6 months and 67.6% ± 9.0% at 1 year. Serious complications occurred in 6 patients (20%), involving 8 of 60 implanted leads (13.3%). The rate of serious complications across all patients undergoing iMRI-guided DBS at the authors’ institution was further reviewed, including an additional 53 patients undergoing GPi-DBS for Parkinson disease. In this expanded cohort, serious complications occurred in 11 patients (13.3%) involving 15 leads (10.1%). CONCLUSIONS Intraoperative MRI–guided lead placement in patients with dystonia showed improvement in clinical outcomes comparable to previously reported results using awake MER-guided lead placement. The accuracy of lead placement was high, and the procedure was well tolerated in the majority of patients. However, a number of patients ex- perienced serious adverse events that were attributable to the introduction of a novel technique into a busy neurosurgical practice, and which led to the revision of protocols, product inserts, and on-site training. https://thejns.org/doi/abs/10.3171/2019.6.JNS19548 KEYWORDS dystonia; deep brain stimulation; intraoperative MRI; interventional MRI; ClearPoint; globus pallidus; asleep DBS; functional neurosurgery J Neurosurg October 11, 2019 1 ©AANS 2019, except where prohibited by US copyright law