Electrical stimulation of the prelemniscal radiation in the treatment of Parkinson's disease: An old target revised with new techniques

OBJECTIVE: In the treatment of tremor and rigidity in patients with Parkins on's disease (PD), the prelemniscal radiation (RAPRL), a subthalamic bundle of fibers, is an exquisite target that can be visualized easily on ventric ulograms. We sought to evaluate the effect of electrical stimulation of the RAPRL on symptoms and signs of PD in a long-term trial and to determine th e localization of the stimulated area by means of stereotactic magnetic res onance imaging studies. METHODS: Ten patients with PD predominantly on one side had tetrapolar elec trodes stereotactically oriented through a frontal parasagittal approach to the RAPRL contralateral to the most prominent symptoms. Preoperative and p ostoperative evaluations at 3, 6, 9, and 12 months after surgery were perfo rmed using conventional PD scales and quantitative evaluations of tremor am plitude and reaction time. Stereotactic high-resolution magnetic resonance imaging studies with the electrodes in place were used for anatomic localiz ation. RESULTS: In all patients, temporary suppression of tremor occurred when the electrodes reached the target. The most effective stimulation was obtained when the pair of contacts was placed in the RAPRL. Long-term stimulation a t 130 Hz, 0.09 to 0.450 milliseconds and 1.5 to 3.0 V produced significant improvement in tremor and rigidity and mild improvement in bradykinesia. CONCLUSION: The RAPRL is an effective target for the alleviation of tremor and rigidity in patients with PD by either lesioning or neuromodulation; ho wever, neuromodulation has the advantage of not inducing an increase in bra dykinesia. The stimulated area seems to be independent of the subthalamic n ucleus.