Long-latency somatosensory evoked potentials during carotid endarterectomy.

Scalp recorded somatosensory evoked cortical responses (SSEP) may be measured under general anesthesia to assess the electrical responsiveness of the brain. Such potentials were measured in 25 patients undergoing carotid endarterectomy without shunt. Electrical unresponsiveness occurred bilaterally in one patient and unilaterally in one patient. The patient with unilateral electrical silence developed a perioperative stroke, the only stroke in this series. Analysis of the SSEPs recorded from these patients suggests that profound ischemia produces electrical silence: that intermediate degrees of ischemia produce prolonged interpeak latencies and decreasing amplitudes in the SSEP. This modality seems to offer promise as an intraoperative monitor during cerebrovascular surgery.

Cognitive improvement after extracranial reconstruction for the low flow--endangered brain.

Twelve patients with multiple occlusive neck vessel lesions were thought to possess low flow-endangered brains. These patients were studied before and after carotid reconstruction with a battery of neuropsychologic tests emphasizing memory and mental agility. A closely matched control group was selected from patients undergoing endarterectomy for hemodynamically insignificant lesions. The patients with low flow-endangered brains showed significantly greater improvements in memory and mental abilities than did the control group. Reconstruction of neck vessels may reverse such global neurologic deficits in carefully selected patients.