Use of somatosensory evoked potentials for intraoperative monitoring of cerebral and spinal cord function.
EPs can be used in the operating room for monitoring the integrity of many levels of the central nervous system. SEPs can monitor the spinal cord, brain stem, and cerebral hemispheres. Such monitoring can alert the surgical team to the presence of complications, allowing prompt correction in some cases so as to prevent postoperative neurologic deficits. Monitoring can be done from stimulation of either the lower or upper extremity. Recordings can be taken over the scalp or can be made from electrodes put into the surgical site itself. Monitoring of the spinal cord is most often done for surgery involving scoliosis, spinal tumors, or arteriovenous malformations, and during crossclamping of the thoracic aorta. Animal models and human surgical experience has shown that monitoring the posterior columns is an effective way to assess the status of the motor pathways of the spinal cord, because the two pathways are both affected in almost all acute circumstances. Monitoring can also assess the functional status of the cerebral hemispheres. This is most often applied during carotid endarterectomy or repair of aneurysms of the carotid artery and its branches. Occasionally, this has also been applied to monitoring the cortex during cardiopulmonary bypass. Such EP monitoring does not cover the wide areas of cortex that can be monitored using EEG, but the EPs do tend to change and disappear at a level of ischemia nearer to the true critical level. Intraoperative median nerve EPs can also be used to identify the hand level of the motor and somatosensory cortex. Such identification of motor cortex can help guide neurosurgeons in their choice of how or where to perform a biopsy, excision, and the like. Overall, intraoperative evoked potential monitoring is becoming widespread because it is a practical way to help avoid neurologic complications, and it can be carried out using equipment already available in many hospitals. A substantial further review in this field can be found in Evoked Potential Monitoring in the Operating Room.
Nuwer
M R
MR
UCLA Department of Neurology, Reed Neurological Research Center.
D001927:Brain Diseases / Q000503:physiopathology* / Q000601:surgery; D005073:Evoked Potentials, Somatosensory; D006801:Humans; D008991:Monitoring, Physiologic; D013118:Spinal Cord Diseases / Q000503:physiopathology* / Q000601:surgery