Unilateral Stimulation of Prelemniscal Radiations for the Treatment of Acral Symptoms of Parkinson's Disease: Long-Term Results.

BACKGROUND: Prelemniscal radiations (Raprl) have been proposed as a target for the treatment of Parkinson's disease. We evaluated effectiveness of this target through UPDRS-III in patients treated with Raprl deep brain stimulation (Raprl-DBS) and followed from 24 to 48 months. METHODS: Nineteen patients in Hoehn-Yahr stages II-III were implanted with tetrapolar deep brain stimulation electrodes in Raprl contralateral to the extremities with more prominent symptoms. Placement was assisted by MRI/CT/anatomical atlas fusion, microelectrode recording, and micro- and macro-stimulation. The effect on motor symptoms was evaluated in an open label protocol through specific items of the UPDRS-III score, applied pre-operatively and 6, 12, 24, and 48 months after the onset of stimulation in an OFF-medication/ON-stimulation condition. Changes in scores with regard to pre-operative condition were obtained for each symptom in both sides and statistical significance determined through double-tail Wilcoxon test. Influence of demographic variables on outcome was analyzed using linear regression testing. RESULTS: A greater than 80% decrease in UPDRS score for contralateral symptoms (classified as excellent results) occurred in 14 patients (73.7%), while in the other 5 it decreased from 33 to 79% (considered suboptimal results). These changes remained statistically significant up to 48 months (p < 0.01), while ipsilateral symptoms progressively increased. Suboptimal results were associated with selective improvement of only one symptom. CONCLUSION: Raprl-DBS induces a long-term, significant improvement of contralateral acral symptoms of Parkinson's disease.

Optimizing Prelemniscal Radiations as a Target for Motor Symptoms in Parkinson's Disease Treatment.

OBJECTIVE: To better define prelemniscal radiations (Raprl) as a target for the control of tremor and rigidity in Parkinson's disease (PD). METHODS: A total of 36 deep brain stimulation (DBS) electrodes were stereotactically implanted in Raprl contralateral to the extremities to be treated. Effects on symptoms were evaluated using UPDRS-III before and after DBS, and significance was determined using the Wilcoxon test. The location of DBS contacts in cases with optimum versus suboptimum results was evaluated using Student's t test and percentage improvement correlated through a bivariable Pearson test. The power and percentage of spike components for microelectrode recordings were statistically compared between the target point and structures located above and below. RESULTS: Raprl-DBS improved tremor and rigidity (p < 0.01). The potency of microelectrode recordings indicated that the target was formed by fibers. There was no correlation between demographic characteristics and clinical outcome, and there were no significant differences in stereotactic placement between cases with optimum and suboptimum results. Tremor and rigidity were selectively improved in cases with suboptimum results. CONCLUSION: Raprl-DBS is an effective treatment for the motor symptoms of PD. Selective improvement of symptoms suggests that the target has different fiber components related to either tremor or rigidity, and variations in improvement between cases may derive from individual variations of the location of these fibers.