Targeting the basal ganglia for deep brain stimulation in Parkinson's disease

The revitalization of surgery for Parkinson's disease (PD) has fueled discu ssion about the best methodology to define the target. Placement of electro des for deep brain stimulation (DBS) requires the usual stereotactic techni que but the argument is mainly centered on whether or not microrecording ne uronal activity is necessary. We compared the accuracy of calculating the c oordinates X (medio-lateral) and Y (rostro-caudal) considered by the classi c stereotactic method, i.e,, definition of the AC-PC intercomissural line b y MRI and a digitized version of the Schalten-brand's atlas, with final ele ctrode placement according with microrecording and microstimulation in 21 p atients. For both the globus pallidum internum (GPi) (n = 21) and the subth alamic nucleus (STN) (n = 36) there was, respectively, a 43% and 45% mismat ching of more than 3 mm between the theoretic coordinates and the final sit e of electrode location. This applies to both the X and Y planes. Accuracy was not, improved in patients (n = 11) in whom the bilateral procedure was undertaken in a single day. We conclude that proper electrode positioning o f the STN and GPi requires fine electrophysiologic assessment.