Effects of electrical stimulation of the gasserian ganglion on regional cerebral blood flow after induced subarachnoid hemorrhage in pigs evaluated by Tc-99m-HMPAO-SPECT

It could be demonstrated that cervical spinal cord stimulation increases ce rebral blood flow. The effects of electrical stimulation of the trigeminal ganglion in the acute phase of SAM in pigs were investigated. The experimen ts were carried out on 11 domestic pigs divided in two groups (group I: SAM [n = 5]; group II: SAM and trigeminal stimulation [n = 6]). In all animals a native SPECT was performed. The Gasserian ganglion was exposed for inser ting the stimulation electrode. SAH was induced by injecting 10 mi autologo us blood through a catheter placed in the suprasellar cistern. 30 minutes a fter SAM-induction electrical stimulation was started for two hours in grou p 11 (2.8-4.5 V, 50Hz, 300 mus). Tc-99m-HMPAO (400-540 MBq) was injected in travenousely 110 minutes later. In group I 99mTc-HMPAO was applied after th e same time interval. 80 minutes later SPECT was performed. Data were proce ssed to calculate the uptake of radioactivity (%/kg tissue weight). The mea n values were calculated for the different groups: native animal examinatio n (%/kg tissue weight): 0.6343; group I: 0.468; group II: 0.6533. Comparing the mean values a highly significant difference between group I and group II (p <0.01) and between native examination and group I (p<0.01) could be f ound. No statistical significance could be detected on comparing the left/r ight-ratio in any ROI. The electrical stimulation of the Gasserian ganglion leads to a significantly increased uptake of Tc-99m-HMPAO after induced SA M. Maybe the stimulation of the Gasserian ganglion constitutes a new therap eutic modality treating disturbed rCBF after SAH.