Usefulness of neurophysiologic techniques in stereotactic subthalamic nucleus stimulation for advanced Parkinsonʹs disease

Objective: The objectives of this study are to determine the impact of neurophysiologic guidance on subthalamic nucleus (STN) targeting and to assess its safety and effectiveness. Methods: We have compared the initial theoretic anatomic target (TAT) of the STN with the final microrecording guided coordinates in 15 consecutive patients with bilaterally implanted electrodes in the STN. The clinical results and adverse effects are also reported. All comparisons were done through a paired Studentʹs t test and Pearsonʹs correlation test. Results: Neurophysiological guidance changed the target coordinates in 26 of the procedures. The mean correction applied to the TAT in order to place the electrode in its definite location was 0.4 mm (±0.8, range 0–3; P=0.03) in the medial-lateral axis, 1.6 mm (±1.2, range 0–5; P=0.01) in the anterior-posterior plane and 0.8 mm (±0.8, range 0–3; P=0.26) in the vertical axis. The mean number of microrecording tracks employed to localize each STN was 2.8±1.8 (range 1–8) tracks. After surgery, the total UPDRS motor score in the off medication condition improved by 65.9%; UPDRS-II scores were reduced by 71.8% and Schwab and England scores improved by 45.3%. No intraoperative hemorrhages occurred in this series. Conclusions: Neurophysiological guidance is a safe and useful tool in order to improve and confirm target localization. The correction applied in the target resulted in a significant clinical improvement 6 months after surgery.