CEREBRAL HEMODYNAMICS AND CEREBRAL METABOLISM DURING COLD AND WARM STRESS

The purpose of this study was to examine if local thermo-applications affect central nervous reactions. in a crossover study, six normal, he althy volunteers at first received cold packs (Cryogel, 8-12 degrees C ; Pine GmbH, Hamburg, Germany) and afterwards hot packs (Parafango, 50 -60 degrees C; Pine GmbH), and another six volunteers started with the hot packs and had the cold packs later; both groups administered the hot and cold packs to their thighs. Before, during, and after treatmen t, cerebral blood flow velocity (CBFV) in the middle cerebri-artery (( MCA)) was measured continuously by transcranial Doppler sonography, wh ereas cerebral respiratory chain enzyme cytochrome aa3 (cCytaa3) and c erebral oxygen saturation (cHbO(2)) were measured by transcranial near infrared spectroscopy in frontal brain tissue. Furthermore, CO2 end-t idal and arterial blood pressure (noninvasive) were also measured. Six other volunteers received only one treatment; therefore, 15 measureme nts with cold and 15 measurements with hot packs were performed. Durin g application of cold packs, a decrease of cHbO(2) of 10.5% (P < 0.001 ) and cCytaa3 of 6.7% (P < 0.001) was found, whereas the CBFVMCA incre ased significantly (3.9%; P < 0.001) between preliminary and post-stim ulus periods. When cold packs were removed, a significant increase of the cHbO(2) (16.9%; P < 0.001) and cCytaa3 (9.7%; P < 0.001) was measu red. With these values, cHbO(2) and cCytaa3 showed an overshooting cou nter-reaction beyond the initial level, When applying the hot packs, a contrary course of the parameters was found. cCytaa3 showed a signifi cant increase of 9.3% (P < 0.001) at the end of the stimulus phase and a decrease of 1.9% (P = 0.02) during the post-stimulus period. The co rrelating increase of cHbO(2) was significant at 13.7% (P < 0.005). Al the end of the post-stimulus phase, a significant decrease of cHbO(2) at 1.9% (P = 0.004) was recorded, With Parafango applications, a sign ificant decrease of CBFVMCA at 6.9% (P < 0.001) was measured at the en d of the stimulus in comparison with the preliminary phase. Crossover analysis showed no significant period effects and intraindividual chan ges between period and treatment. Therefore, both treatments can be co mpared within the individual using paired t test. Local cold and warm stimuli influence the cerebral hemodynamics and cerebral metabolism. C erebral hemodynamics (CBFVMCA in comparison with cerebral metabolism ( cCytaa3, cHbO(2)) show opposite reactions under thermo-stress, Of spec ial interest is the overshooting counter-regulation of cerebral metabo lism after cold stimulation. These effects may open new thermotherapeu tic aspects in central nervous system diseases.