Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology
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Comparative Study
The subthalamic nucleus in Parkinson's disease: power spectral density analysis of neural intraoperative signals.
To test a new tool for the neurophysiological identification of the human subthalamic nucleus (STN) during stereotactic surgery for the implantation of deep-brain-stimulation (DBS) electrodes, we analysed off-line the intraoperative signals recorded from patients with Parkinson's disease. We estimated the power spectral density (PSD) along each penetration track (8 patients, 13 sides) and determined the spatial correlation of the PSD with the target location estimated from neuroimaging procedures ("anatomical target"), and with the final target location derived from standard intraoperative neurophysiological procedures for STN localization ("clinical target"). At each step we recorded the 'on-line' signal for 120 seconds; because the PSD was estimated by calculating the periodogram for 6-second epochs of neural signal, we had 20 epochs at each step. ⋯ When the track was outside the nucleus, the PSD remained unchanged. Even on recordings with low signal-to-noise ratio, off-line PSD analysis of neural signals showed a good correspondence with the target indicated by the surgical team. On-line intraoperative estimation of the PSD may be a simple, reliable, rapid and complementary approach to electrophysiological monitoring during STN surgery for Parkinson's disease.