CEREBRAL BLOOD-FLOW CHANGES INDUCED BY ELECTRICAL-STIMULATION OF THE GASSERIAN GANGLION AFTER EXPERIMENTALLY INDUCED SUBARACHNOID HEMORRHAGE IN PIGS

The effect of trigeminal electrical stimulation on cerebral blood flow has been studied in conditions of normal or reduced cerebral blood flow (CBF). Autologous blood was injected into the subarachnoid space of ten Pittmann-Moore pigs to induce subarachnoid haemorrhage (SAH) accompanied by cerebral blood flow (CBF) reduction. One week later, in six of ten animals, a considerable decrease of CBF was noted as evaluated by means of a recording-system monitoring over the right parieto-temporal calvarium the washout of Xenon-133 injected into the internal carotid artery after the external carotid had been clamped. Continuous electrical stimulation of the Gasserian ganglion performed in the six animals with severely induced CBF reduction produced a remarkable cerebrovascular dilation and increase of CBF lasting over 3 h. Electrical stimulation of the Gasserian ganglion produced a similar pattern of vasodilation in six pigs in which no blood was injected and no reduction of CBF was evident. The mechanisms and the anatomical pathways which underlie these results are discussed.