Preliminary Measurement of Intraoperative Sympathetic Nerve Activity Using Microneurography and Laser Doppler Flowmetry During Surgical Resection of Suprasellar Tumors

Abstract

Intraoperative microneurography (enabling direct measurement of sympathetic outflow) and laser Doppler flowmetry were used to measure skin sympathetic nerve activity (SSNA) and skin blood flow (SBF) as indicators of hypothalamic damage during resection of 12 suprasellar tumors, 6 craniopharyngiomas, 4 meningiomas, 1 pituitary adenoma, and 1 germ cell tumor. SSNA was measured from a tungsten microelectrode inserted into the peroneal nerve, and SBF was measured from the foot innervated by the peroneal nerve. SBF reduction was induced by nociceptive procedures and non-nociceptive procedures before tumor exposure, on exposed tumors, and directly on the hypothalamus. SSNA could be reliably recorded in only 4 patients because of technical difficulties. In these patients, SSNA bursts appeared, followed by SBF reduction. The number of SSNA bursts was 37% to 100% of the number of SBF reduction events. Various surgical procedures involving painful stimuli or mechanical stress on the hypothalamus induced SSNA bursts and SBF reduction. The present findings suggest that SSNA and SBF can be used to detect sympathetic nerve activity, as an indicator of hypothalamic function, during neurosurgical procedures.