Physiologic study of the subthalamic volume

Deep brain stimulation (DBS) obtains good control of advanced PD symptoms. Chronic stimulation of Stn may alleviate rigidity, dyskinesia and tremor. A natomical and functional intraoperative mapping are mandatory to obtain car eful target localisation. Per-operative macrostimulation was carried out in 22 patients undergoing bilateral DBS in Stn; a volume 6 mm above to 4 mm b elow Stn was explored. Positive, collateral and adverse effects were record ed every 2 mm. Results obtained during acute stimulation were correlated to anatomical data from stereotactic atlases. Our findings suggest a volume, encompassing the zona incerta, Forel's fields and the lowermost part of ant erior thalamus, functionally homogeneous to Stn. In fact, the stimulation o f this volume obtains reduction of PD symptoms comparable to Stn.