Neurophysiologie clinique = Clinical neurophysiology
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During resection of intramedullary spinal-cord tumors intraoperative neurophysiological monitoring has become a true surgical technology. Motor evoked potentials are the most important modality for this purpose. Its use requires neurophysiological expertise from the surgeon, and a monitoring team in place able to handle the necessary equipment. ⋯ Such adaptation comprises simply waiting for the recordings to spontaneously improve again, irrigating with warm saline solution to wash out blocking potassium. Other measures include the elevation of mean arterial pressure to improve local perfusion. Even staged resection can be considered if intraoperative measures do not sufficiently improve the recordings.
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Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is increasingly used to treat advanced Parkinson's disease (PD). The optimal method for targeting the STN before implanting the definitive DBS electrode is still a matter of debates. Beside methods of direct visualization of the nucleus based on stereotactic magnetic resonance imaging (MRI), the most often used technique for targeting STN consists in recording single-cell activity along exploratory tracks of 10-15mm in length, centered on the theoretical or MRI-defined target coordinates. ⋯ Signal amplitude significantly increased at the both rostral and caudal STN margins (P<0.05) and the level of neuronal activity easily distinguished inside from outside the nucleus. This study showed that STN boundaries could be adequately determined on the basis of intraoperative multi-unit recording with a semi-microelectrode. The accuracy of our method used for positioning DBS electrodes into the STN was confirmed both on CT-MRI fusion images and on the rate of therapeutic efficacy.
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To analyse the parallel use of transcranial electrical stimulation (TES) and direct cortical stimulation (DCS) for eliciting muscle motor evoked potentials (MMEPs) in intracranial aneurysm surgery; to correlate permanent or transient TES- and/or DCS-MMEP changes with surgical maneuvers and clinical motor outcome. ⋯ In aneurysm surgery, provided that close-to-motor-threshold stimulation and the most focal stimulating electrode montage are used, TES- and DCS-MMEPs do not differ in their capacity to detect an impending lesion of the motor cortex or its efferent pathways. TES stimulation can cause significant muscular contraction during surgery, potentially disrupting the operating surgeon. DCS maintains the singular advantage of stimulating a very focal and superficial motor cortex stimulation that does not result in patient movement.
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New motor deficit after surgery for deep-seated gliomas can occur from subcortical ischemia of the pyramidal tract. Motor evoked potentials (MEPs) validly indicate impending motor tract ischemia in cerebrovascular surgery. This study determines the feasibility and clinical utility of MEP monitoring for ischemic complication avoidance during surgery for deep-seated, specifically insular gliomas. ⋯ Ischemia in deep-seated glioma surgery usually occurs uncorrelated to resection close to the pyramidal tract. MEP monitoring efficiently helps detect ischemia early and to avert definite stroke and permanent new paresis in part of these cases.
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Entrapment of the pudendal nerve may be at the origin of chronic perineal pain. This syndrome must be diagnosed because this can result in the indication of surgical decompression of the entrapped nerve for pain relief. Electroneuromyographic (ENMG) investigation is often performed in this context, based on needle electromyography and the study of sacral reflex and pudendal nerve motor latencies. ⋯ Pudendal neuralgia related to nerve entrapment is mainly suspected on specific clinical features and perineal ENMG examination provides additional, but no definitive clues, for the diagnosis or the localization of the site of compression. In fact, the main value of ENMG is to assess objectively pudendal motor innervation when a surgical decompression is considered. Perineal ENMG might predict the outcome of surgery but is of no value for intraoperative monitoring.