Postoperative gait deterioration after bilateral subthalamic nucleus stimulation in Parkinson's disease

Deep brain stimulation of the subthalamic nuclei (STN) is a good therapeutic option to reduce dyskinesias and improve appendicular motor signs in well‐selected patients with advanced Parkinson's disease (PD). Concerns about long‐term adverse effects play an increasingly role in the decision whether or not to refer patients for this treatment. Worsening of gait as a consequence of STN stimulation for PD has been described, but may be under‐recognized in clinical practice. The aim of this study was to evaluate the effects of STN stimulation on gait relative to global outcome in a group of consecutively operated patients. For this purpose, we used a standardized patient questionnaire that asked about global outcome and specific effects on gait, as experienced both 6 months postoperatively and currently (at the time of completing the questionnaire; mean: 2.7 +/? 1.1 years). A delayed worsening of gait after bilateral STN stimulation was experienced by a considerable proportion of patients (42% of subjects, for gait in the OFF phase), and this was apparently relatively “selective” because their global outcome scores continued to be improved. These findings highlight the presence of a hitherto poorly recognized long‐term complication of bilateral STN stimulation. Further systematic studies are required to pinpoint the clinical and surgical determinants of this late gait deterioration. © 2008 Movement Disorder Society