Correlation of active contact positions with the electrophysiological and anatomical subdivisions of the subthalamic nucleus in deep brain stimulation.

BACKGROUND

The most effective contacts in subthalamic nucleus (STN) deep brain stimulation are reported to be dorsolateral, and suppression of synchronized oscillatory activity might be a mechanism of action.

OBJECTIVES

To analyze the optimal contact position in regard to the anatomical and electrophysiological position and to determine whether oscillatory and bursty activity is more frequent around the active contact.

METHODS

In 21 patients, the clinically most effective contacts were analyzed according to their relative position to the anatomical and electrophysiological STN center, which was assessed by T2-weighted MRI and microrecording. In 12 out of 21 consecutive patients, autocorrelograms of the action potentials within the vicinity of the active contact were compared to the most ventromedial reference contact.

RESULTS

The isocenter of the anatomical and electrophysiological STN had a mean deviation of 0.8 mm (SD 1.45). Thirty-two out of 42 active contacts were found dorsal to the anatomical isocenter of the STN. None of the active contacts were ventral to the STN. Synchronized oscillatory or bursty activity was found in 67% of the patients within the vicinity of the active contact. In 64% of the patients, the ventromedial reference contact showed irregular activity.

CONCLUSIONS

Synchronized activity in the autocorrelogram correlates with the most effective contact. The optimal localization of the finally stimulated contact is dorsal to the STN isocenter.