The Advantage of Microelectrode Recording When Pneumocephalus Threatens the Precise Placement of a Deep Brain Stimulator.

Clinical Vignette: A 69-year-old woman with Parkinson's disease underwent left subthalamic nucleus (STN) deep brain stimulation (DBS). Intraoperative awake microelectrode recording (MER) was used to confirm targeting. Clinical Dilemma: MER and stimulation mapping revealed a short STN segment on the central pass, absent STN activity on the lateral pass, and low thresholds for capsular side effects. The data suggested a mismatch between the planned imaging-based trajectory and the localization of STN using physiology. Clinical Solution: A substantial adjustment based on MER was required, giving up the 'fork' in the brain. The lead was repositioned 3.4 mm posterior and 2.9 mm medial to the initial central pass (4.9 mm vector). Final placement produced robust motor benefit and a desirable therapeutic window for programming. Gap in Knowledge: Asleep image-guided workflows assume static intracranial anatomy: pneumocephalus can induce millimetric brain shift. This case demonstrated a pneumocephalus-related displacement and how MER, stimulation thresholds, and postoperative atlas-based validation can be employed to correct it. Highlights: This case illustrates how intraoperative pneumocephalus can compromise targeting in deep brain stimulation.Microelectrode recording provided critical confirmation, guided corrective lead adjustments, and safeguarded therapeutic outcomes, emphasizing the value of physiology-based targeting alongside modern imaging techniques.