Advances in Bioscience and Bioengineering

A long historical experience of monofrequency rheoencephalography (REG) showed its limited capabilities. The new approach is presented – multifrequency REG that is REG recording simultaneously at three frequencies 16, 100 and 200 kHz. The different brain impedances received were analyzed on the base of equivalent electrical circuits of brain tissue. First, this enables to calculate intra-extracellular electrical component for evaluation of brain tissue hydration state by means of an original computational method. Second, dynamic cooperative analysis of multi-REG and transcranial Doppler pulsations provides the indices of intracranial CSF mobility (CSFm) and cranial compliance (CCe). Third, spectral analysis of processes recorded provides the new valuable information about regulatory processes and brain metabolism involved, and this enables to evaluate indirectly brain cognitive capabilities. Fourth, comparison of spectrum diagrams of slow intracranial volume fluctuations in ranges 0 – 0.3 Hz demonstrates their similarity both in healthy human and in awake rabbits, notwithstanding their rates differences of heart pulsations and respiratory chest movements. The application of this new approach to investigation of intracranial circulation in healthy humans of different ages and in neurosurgical patients showed its promising efficacy.