Neuromodulation of prelemniscal radiations in the treatment of Parkinson's disease.

In patients with Parkinson's disease (PD), tetrapolar electrodes were implanted in the prelemniscal radiations (RAPRL) to treat tremor, rigidity and bradykinesia. Fifteen patients were implanted unilaterally and five patients bilaterally and followed-up for one year. The selection criteria included the presence of unilateral pronounced tremor and rigidity in patients implanted unilaterally or bilateral symptoms including severe bradykinesia in patients implanted bilaterally. In the operating room, the tremor decreased significantly or was abolished following the insertion of the electrode in the RAPRL. This effect was temporary and subsided when the stimulation was off. However, when the stimulator was turned on, the severity of the symptoms and signs decreased significantly. The post-implantation MRI confirmed that the electrode contacts used for stimulation were inserted in RAPRL, a group of fibers located between the red nucleus and subthalamic nucleus, above the substantia nigra, medially to the zona incerta and below the thalamus. The patients were evaluated using the UPDRS part III, before implantation and every 3 months during the first year. Global scores decreased significantly. The pre- and postoperative median values (range in round brackets) were as follows: tremor improved from 3 (2-16) to 1 (2-3) (p<0.001); rigidity was either abolished or decreased markedly from 2 (1-16) to 0 (0-4) (p< 0.001); bradykinesia improved from 2 (0-4) to 1 (0-2) (p<0.001). We conclude that RAPRL, an area anatomically different from STN, is a good target for electrical stimulation in order to treat effectively all the main symptoms of PD.