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cerebral artery strips. An article from the "Fukushima Journal of Medical Science," 1987, 33:55-70, demonstrated that prevention of cerebral vasospasms by the use of ascorbic acid which prevents the degradation of oxyhemoglobin. What causes cerebral vasospasms remains elusive, however, we are closer to its understanding.
We can see that vasospasms that could cause the loss of a patient with an aneurysmal subarachnoid hemorrhage occurs more often because of the shear number of patients with traumatic brain injury. Because we are looking to prevent secondary injury in patients with traumatic head injury, we should invest more time and understanding into this very deadly problem.
ELECTROPHYSIOLOGICAL MONITORING FOR NEUROSURGERY
LECTURE NOTES FROM MULTIPLE SOURCES FOR SLIDES
NOT ORIGINAL WORK
Monitoring nervous system functions during surgery is not a new venture. Neurosurgeons have operated under local anesthesia to monitor neurological functions and changes as a result of surgical manipulation or arterial occlusion. Eliciting motor responses after stimulation has been used for decades to map the cerebral cortex during epilepsy surgery. Surgical treatment of tumors at the base of the skull carries significant risk to the functioning of the cranial nerves, the brain stem, and the cerebral hemispheres. This risk is due both to problems associated with maintaining adequate blood supply to the brain stem and cerebral hemispheres and to the effect of various operative maneuvers aimed at adequately exposing the tumor and removing it. These risks may he reduced if appropriate information concerning the relationships between surgery and the anatomical structures.
Intraoperative neurophysiological monitoring provides a real-time control loop around a system composed of the surgeon and the patient. The goals of this control loop are both the reduction of morbidity and a dynamic assessment of structure-function relationships of the patient's nervous system. The surgeon needs information about the functional status of the nervous system, during surgery, in order to adapt the surgical strategy in such a way as to minimize morbidity. Immediate knowledge of the physiological effect of each surgical manipulation is irreplaceable. It has long been appreciated that the patient's physiological status is dynamic, and that during surgery rapid and life-threatening changes may occur. This realization has led to the sophisticated patient monitoring by anesthesiologists where extensive physiological monitoring is routinely used to maintain the homeostatic status of the patient. This monitoring may be thought of as putting a control loop around the anesthesiologist and the patient for the purposes of life support. Some information is available from these procedures that also reflect the stress on the central nervous system, for (Continued on page 102)
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