Localization of Motor Cortex with Median Nerve Somatosensory Evoked Potentials
Motor cortex localization can be helpful during a craniotomy. Somatosensory evoked potentials (SSEP) can help with this task. The primary cortical SSEP from median nerve stimulation is generally easily and quickly defined on the exposed cerebral cortex. Several types of recording electrodes can be used. Interpretation is usually based upon several features, including the maximum N20 amplitude, phase reversal of N20-P20 across the central fissure, and the presence of small step-like negative potentials leading up to the N20 over the primary sensory cortex. Localization of the motor cortex is most often applied in situations in which the surgeon can use some discretion in defining the limits of a resection or the location of a biopsy.
It can be advantageous to identify the motor cortex during a craniotomy. The complexities fo sulci and gyri anatomy are somewhat too variable and unpredictable to be reliable by themselves. Somatosensory evoked potentials (SSEP) provide a means of helping the surgeon identify the primary postcentral somatosensory cortex, thereby also establishing the location of the precentral motor cortex. This technique is relatively quick and simple, and it can be used without substantial problems or complications in many various circumstances.
KeywordsAttenuation Neuropathy Assure Isoflurane Halothane
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- Lesser RP, Lüders H, Dinner DS, Morris HH, Wyllie E (1989) Extraoperative monitoring of patients with intractable seizures. In: Desmedt JR (ed) Neuromonitoring in Surgery. Elsevier, Amsterdam, The Netherlands, pp 303–318Google Scholar
- Nuwer MR (1986) Evoked Potential Monitoring in the Operating Room. Raven Press, New YorkGoogle Scholar
- Penfield W, Jasper HH (1954) Epilepsy and the Functional Anatomy of the Human Brain. Little, Brown, and Company, BostonGoogle Scholar