Bilateral electrical stimulation of prelemniscal radiations in the treatment of advanced Parkinson's Disease

OBJECTIVE: Tremor and rigidity have been efficiently controlled by electrical stimulation of contralateral prelemniscal radiations (Raprl) in patients with unilateral Parkinson's disease. The present study determines the effect of bilateral Raprl electrical stimulation in a group of patients with severe bilateral tremor, rigidity, and bradykinesia. METHODS: Five patients with Parkinson's disease (Hoehn and Yahr scale, Stage V) underwent bilateral stereotactic electrode implantation. Postoperative magnetic resonance imaging studies confirmed their position. Bipolar chronic electrical stimulation was performed through contiguous contacts of each electrode, which were selected by means of a screening test that explored multiple combinations. Preoperative and 3-, 6-, 9-, and 12-month postoperative evaluations were performed using international rating scales. Postoperative evaluations were performed with 24 hours off medication-on stimulation. RESULTS: Contralateral tremor and rigidity were significantly decreased by simple insertion of electrodes in Raprl and returned hours to days later. Contacts for chronic stimulation were located in the area between the red and subthalamic nuclei, including Raprl, zona incerta, and substantia Q. Efficient stimulation had at least one contact in Raprl and in four cases, both contacts were only in Raprl. Stimulation parameters were 90 to 130 Hz, 90 to 330 mu s, and 1.5 to 3.5 V. Unified Parkinson's Disease Rating Scale (motor, Part 111) scores decreased 65% (P< 0.001), with improvements of 90% in tremor (P < 0.001), 94% in rigidity (P < 0.001), 75% in bradykinesia (P < 0.001), 40% in gait, and 35% in postural stability (P < 0.05) at 1 year. CONCLUSION: Raprl electrical stimulation is safe and efficient to treat patients with the Parkinson's disease symptomatic triad. By use of Raprl stereotactic coordinates, electrodes were placed behind the subthalamic nucleus.