Changes in regional cortical temperature and cerebral blood flow after cortical spreading depression

Regional cerebral blood flow (rCBF) measurement by laser Doppler flowmetry and cortical temperature measurement using thermoencephaloscopy (TES) were performed to investigate the relationship between the changes in rCBF and cortical temperature after induced cortical spreading depression (CSD) in rats. TES showed a gradually expanding thermoresponse like an extending circular wave after CSD induced by application of KCl. Similarly, a transient increase in rCBF spread from the site of stimulation with a velocity of propagation of 2.5 mm/min. Simultaneous monitoring of rCBF and cortical temperature showed that the transient increase in rCBF was associated with an initial decrease in cortical temperature, followed by an increase in cortical temperature. We suggest that the cortical temperature is regulated mainly by neurogenic control of the pial microvascular blood supply that is precisely adjusted to the metabolic needs of the cerebral cortex. Non-injured cortex with the fine vascular architecture must be preserved during neurosurgery to allow heat transfer from deep areas of the cortex.