Implantation of human pedunculopontine nucleus: a safe and clinically relevant target in Parkinson’s disease

The peduncolopontine nucleus modulates locomotor activity and dysfunction in this nucleus may be responsible for the gait and postural impairments seen in Parkinson’s disease and othermovement disorders. We report the ¢rst surgical exploration and implantation of deep brain stimulating electrodes of the peduncolopontine nucleus area in two Parkinson’s disease patients to examine the safety and the potential bene¢t of chronic electrical stimulation at this site.Under local anesthesia, the peduncolopontine nucleus was approached from a coronal burr hole using a trajectory that was 78^ 801 and 62^641 on the coronal and sagittal planes. Microrecordings helped to identify neurons in peduncolopontine nucleus and the adjacent substantia nigra pars reticulata. Chronic deep brain stimulating electrodes were implanted within thepeduncolopontine nucleus in amanner similar to thatpracticed with deep brain stimulating surgery at other targets. Peduncolopontine nucleus neurons were characterized by small and broad multiunits (230 mV, 2.5ms, 14.6Hz). Caudal to this area, neurons ¢ring at higher frequency, approximately 70Hz, characteristic of nigral neuronal discharges, were encountered, followed by 2mm of cells similar to those recorded in the dorsal peduncolopontine nucleus area.After deep brain stimulating electrodes implantation, acute intraoperative stimulation (up to 3V) was performed with two stimulation frequencies in each session. Stimulation at 80Hz has little discernable e¡ect. On the other hand, stimulation at 10Hz fostered a subjective feeling of ‘well-being’and a time-locked amelioration of the clinical scores.These ¢ndings demonstrate that the stereotactic approach of peduncolopontine nucleus is safe. The target may reliably be identi¢ed by microrecordings. Low-frequency stimulation may produce acute improvements in motor function. NeuroReport16:1877^1881c 2005 LippincottWilliams &Wilkins.