Unilateral Microelectrode Recording–Guided Pallidotomy in Advanced Parkinson's Disease: Clinical and Neuropsychological Outcomes in a Guatemalan Cohort

BACKGROUND Unilateral microelectrode-guided pallidotomy has re-emerged as a therapeutic option for advanced Parkinson's disease (PD), particularly in resource-limited settings. This study evaluated motor and neuropsychological outcomes following radiofrequency ablation of the internal globus pallidus (GPi) using image fusion and intraoperative microelectrode recording. To assess the motor efficacy, cognitive impact, and safety profile of unilateral GPi pallidotomy guided by neurophysiological monitoring in patients with advanced idiopathic PD of the rigid-akinetic subtype.

METHODS This retrospective, single-center, observational case series included 12 patients with advanced PD who underwent unilateral radiofrequency pallidotomy targeting the internal segment of the GPi. Movement Disorder Society-Unified PD Rating Scale Part III (MDS-UPDRS-III), including both contralateral and ipsilateral domain sub scores. Levodopa-induced dyskinesias (UPDRS-IV) and cognitive performance (NEUROPSI Attention and Memory battery) were also assessed before and 12 months after surgery. Statistical analyses were conducted using paired t-tests or Wilcoxon signed-rank tests depending on data distribution, with significance set at p < 0.05.

RESULTS At 12-month follow-up, motor outcomes improved significantly. Mean MDS-UPDRS-III scores decreased from 64.1 ± 27.1 preoperatively (OFF medication) to 37.8 ± 24.4 postoperatively, and from 23.5 ± 17.0 to 10.6 ± 8.5 in the ON state. The overall OFF-state improvement was 44.4% ± 21.2%. Paired t-tests confirmed a highly significant reduction in motor scores (t = 6.19, p < 0.0001; mean change -26.3 points, 95% confidence intervals (CI) -34.7 to -18.0). Domain-specific analysis showed significant contralateral improvements in rigidity (-48%, p = 0.0006), bradykinesia (-49.5%, p < 0.0001), resting tremor (-81%, p = 0.004), gait (-27.8%, p = 0.013), postural stability (-39%, p = 0.021), and dyskinesias (-56%, p = 0.017). Ipsilateral changes were mild and not statistically significant for rigidity (-14.6%, p = 0.519), bradykinesia (-25.0%, p = 0.084), or rest tremor (-50.0%, p = 0.121). No major surgical complications occurred. Neuropsychological assessment revealed modest postoperative gains in executive functioning and working memory, with preservation of global cognition.

CONCLUSION Unilateral GPi pallidotomy guided by imaging and microelectrode recording is a safe and effective procedure that significantly improves motor symptoms while preserving cognitive function in appropriately selected patients with advanced PD, as demonstrated in our Guatemalan cohort.