Commentary: Using Directional Deep Brain Stimulation to Co-activate the Subthalamic Nucleus and Zona Incerta for Overlapping Essential Tremor/Parkinson\u27s Disease Symptoms.

We have read with interest the article titled “Using Directional Deep Brain Stimulation to Co-activate the Subthalamic Nucleus and Zona Incerta for Overlapping Essential Tremor/Parkinson\u27s Disease Symptoms” by Falconer et al. (1). In this case report, the authors present a patient treated with unilateral left-sided deep brain stimulation (DBS) after medical management alone proved to be ineffective. The stereotactic target was described as being “3 mm lateral to the most lateral point of the red nucleus” at the Bejjani line (2); and implantation of the electrode at this target was confirmed with microelectrode recordings, intraoperative macrostimulation testing, as well as post-operative imaging. Based on their clinical findings with significant UPDRS improvement and medication reduction, the authors ultimately concluded that DBS in this patient resulted in “possible co-activation of the dorsal aspect of the STN and the adjacent ZI through the utilization of a bipolar directional montage on a single segmented contact.” Although an interesting and exciting concept, we found this interpretation to be misleading