Subthalamic stimulation for Parkinson's disease

Deep brain stimulation by high frequency (HFS) has been developed starting in the thalamic target (Vim) from pragmatic observations and subsequently f ollowed by other targets, such as the subthalamic nucleus (STN) and pallidu m as an application of current knowledge from basic preclinical research in neuroscience. The mechanism involved by this neurosurgical approach is not completely solved. For Vim we have formed the hypothesis that HFS induces a jamming of sensory-motor loops but for the STN, from our experimental res earch in rats we have shown that HFS induces functional inhibition of cell activity in the target nuclei. in our patients the implantation of the stim ulation electrodes was carried out stereotactically, under local anesthesia , using ventriculography, MRI, micro-recordings and clinical evaluation of the effects of stimulation on rigidity. When the stimulation is turned ON i n the STN area a significant decrease in rigidity was determined by the neu rologists. Stimulation or even penetration of the electrode may be responsi ble for transient dyskinesias. The average location of the clinically effic ient contact of the chronic stimulating electrodes is statistically located at 5.02 +/- 0.71 1/12 degrees of AC-PC in the AP direction, at -1.5 +/- 0. 66 1/8 degrees of the height of the thalamus in the ventricle direction, wi th laterality at 11.98 +/- 1.12 mm in the lateral direction. The beneficial , effects of STN stimulation are significant providing that the electrodes are correctly placed into the target. There is strong improvement of the sy mptoms of the triad in which akinesia, rigidity, and tremor are reduced on average to 41.6, 48.6, and 27%, respectively, when compared with the previo us preoperative level. From our experience, HFS of the STN could be conside red the surgical therapy of choice at advanced stages of Parkinson's diseas e, (C) 2000 IMSS. Published by Elsevier Science Inc.