Deep brain stimulation of the subthalamic nucleus for Parkinson's disease:Methodologic aspects and clinical criteria

The technique of deep brain stimulation (DBS) for the treatment of Parkinso n's disease (PD) is evolving very rapidly. The subthalamic nucleus (STN) ha s become the preferred target in the past few years since our group demonst rated that high-frequency stimulation in this nucleus improves all cardinal features of PD, including resting tremor. This benefit in the parkinsonian symptoms allows a drastic reduction in daily levodopa requirements. Dyskin esias become drastically attenuated, possibly as a consequence of reduced d opaminergic medication but also because STN DB may stabilize basal ganglia output activity, thus avoiding the problems associated with standard levodo pa replacement therapy. DBS of the STN is associated with a marked improvem ent of motor function even in patients with advanced PD. Such a large degre e of benefit in parkinsonian features relies on two:crucial points that mus t be taken into consideration for achieving the best possible results with this technique: proper selection of patients and accuracy in targeting the STN. From a neurosurgical point of view, we believe that the most precise l ocalization of the STN is obtained by using ventriculography to determine t he stereotactic coordinates of the STN. This is complemented with intraoper ative neuronal microrecording to define physiologically the sensorimotor re gion of the nucleus. Future advances in neuroimaging techniques may well le ad to modifications of our current methodology.