Deep brain stimulation of the subthalamic nucleus: anatomical, neurophysiological, and outcome correlations with the effects of stimulation

Abstract

Objectives: Bilateral chronic high frequency stimulation of the subthalamic nucleus (STN), through the stereotactical placement of stimulating electrodes, effectively improves the motor symptoms of severe Parkinson's disease. Intraoperative neurophysiological and clinical monitoring techniques (neuronal electrical activity recording and intraoperative stimulation) may improve and refine the localisation of the nucleus. The objective of this work was to compare the preoperative CT and MRI localisation with the intraoperative neurophysiological identification of STN. The relation between the localisation of the STN and the position of the most effective contact of the permanent quadripolar electrode at a 3 month and 1 year follow up was also studied. Methods: Fourteen consecutive parkinsonian patients were submitted to bilateral implant for STN stimulation. All the patients underwent a standard MRI and stereotactic CT to obtain, by image fusion and localisation software, the stereotactical coordinates of STN. The STN extension and boundaries were identified by a semimicrorecording of the neuronal electrical activity. The definitive quadripolar electrode was positioned to locate at least two contacts within the STN recording area. Intraoperative macrostimulation was performed to confirm the correct position of the electrode. Postoperative clinical evaluation of the effects of stimulation was checked for each contact of the quadripolar electrode testing the improvement on contralateral rigidity to select the best contact. This evaluation was repeated at 3 months and 1 year after surgery. Results: In 35.7% of the procedures it was necessary to perform more than one track to get a recording of neuronal activity consistent with STN. The mean position of the central point of all the 28 STN recording areas in respect of the AC-PC line midpoint was 2.7 mm posterior (SD 0.7), 3.8 mm inferior (SD 1.1), and 11.6 mm lateral (SD 0.9), and the mean distance between the anatomical target and the central point of the STN as defined by intraoperative recording was 0.5 mm (SD 0.5) on the anteroposterior plane, 0.7 mm (SD 0.7) on the lateral plane, and 0.9 mm (SD 0.6) on the vertical plane. At 1 year the mean position of the central point of the most effective contact of the electrode in respect of the AC-PC line midpoint was 1.7 mm posterior (SD 0.9), 1.7 mm inferior (SD 1.5), and 12.3 mm lateral (SD 0.9). Conclusion: The results highlight the role of the intraoperative recording to get a more accurate localisation of the STN in surgery for Parkinson's disease, allowing the identification of the boundaries and of the extension of the nucleus. The most effective contact of the quadripolar electrode was always in the upper part of the STN recording area or immediately above it, suggesting a role of this region in the clinical effectiveness of the STN electrical stimulation.

Correlating Clinical Scores with Anatomical Electrodes Locations for Assessing Deep Brain Stimulation

“…Even if results of motor scores studies were almost identical, the visualization of the atlas containing the UPDRS III shows that the postero-superior region was the most effective region for motor improvement. This follows conclusions of previously published works [10,21], and can be explained by the fact that this part of the STN (usually named the dorso-lateral part) is implicated in sensory and motor functions [22].…”

Subthalamic deep brain stimulation: clinical and neuropsychological outcomes in mild cognitive impaired parkinsonian patients

“…Subjects were selected according to the Core Assessment Program for Surgical Interventional Therapies in Parkinson's disease (CAPSIT-PD) [9] and STN-DBS bilateral surgery was performed following the procedure previously described elsewhere [10] .…”

Parkinson’s disease outcomes after intraoperative CT-guided “asleep” deep brain stimulation in the globus pallidus internus

“…Studies of these methods with postoperative imaging to assess final lead location in the STN 3,11,15,20,23,26,33 or GPi 5,14,28,30 revealed important correlations between the precise anatomical lead position and clinical outcome. These data coupled with improved MRI resolution led the way for "direct" targeting, wherein the targeted structure is directly visualized on MRI.…”