Changes of circulatory-metabolic indices and skull biomechanics with brain activity during aging.

The cerebral blood flow values used in experimental and clinical investigations as the informative criteria for brain blood supply are often misleading. The correlation between the cerebral blood supply and brain function is not proven in all cases. An increase of brain activity is known to be accompanied by a rise of blood flow in activated regions, while a decreased activity results in a decreased blood flow. This demonstrates the close correlation between the brain blood supply and its activity. Such a correlation had not been noted in the age-dependent decrease of cerebral blood flow, suggesting the existence of special age-related mechanisms that develop with age to maintain brain metabolism. The biomechanical properties are of special significance as predicted in the early 20th century. Only recently were they validated by the simultaneous recording of Transcranial Dopplerogram and Rheoencephalogram with in-depth analysis focused on single cardiac cycles. Functioning of the intracranial blood and cerebrospinal fluid dynamics was integrated with a special physiological test "Prognosis-2" to measure brain cognitive function. Correlation was demonstrated with the circulatory-metabolic state of brain activity, especially in people with changing cognitive function. The data supports a conceptual model of adequate circulatory-metabolic supply of brain activity, showing the functional unity, which follows from integration of the mentioned systems.

[Interhemisphere asymmetry of the CSF dynamics and biomechanical properties of the skull].

This investigation shows that both intracranial liquor circulation and skull biomechanical properties evaluated by its pliability (compliance) to intracranial pressure are characterised by marked interhemisphere asymmetry. The interhemisphere differences of cerebrospinal fluid mobility were evaluated by means of asymmetry coefficient (right/left ratio of liquor mobility) which was found to be 1.25-1.45 in healthy middle-age persons. For the skull pliability (compliance) the coefficient of hemispheric asymmetry was 0.75-0.95. These two hemisphere asymmetry coefficients are characterized by reciprocal relationships. These coefficients demonstrated no dominancy related to right/left hemisphere as well as no correlation with neurophysiological parameter. Functional tests (apnoea, hyperventilation, Stookey test) gave rise to significant changes of these coefficient values. At ageing, the magnitudes of these coefficients decreased. The spectral analysis of pulse waves of dopplerogram and rheoencephalogram reveals hemisphere asymmetry, too. It should be suggested that the interhemisphere asymmetry of the CSF dynamics and skull biomechanical properties is a special mechanism which contributes in the process of circulatory-metabolic support of brain activity.

Slow-wave oscillations in the craniosacral space: a hemoliquorodynamic concept of origination.

The mechanism of formation of rhythmic, slow-wave oscillations in the craniospinal cavity were studied. Synchronous bioimpedance traces were made of the head and lumbosacral part of the spine in five healthy young subjects at rest and during voluntary breath-holding; these reflect changes in the ratios of blood and CSF volumes in these parts of the craniospinal space. Computer amplitude-frequency and spectral analysis of the data (Macintosh G-4, Chart-5.2) demonstrated slow (6-12 cycles/min) and rapid (pulsatile) oscillations in different directions in the cranial and lumbosacral areas. These data suggested a hemoliquorodynamic hypothesis for the craniosacral rhythm. The pulsatile and slow-wave oscillations of cerebrovascular tone and intracranial pressure evidently initiate to-and-fro displacements of the CSF in the caudal direction. The associated tonic contractions of the musculature of the lumbar part of the spine and the mobility of the sacrum are detected manually as the craniosacral rhythm.

[Age-related characteristics of relationships between brain blood flow, liquor dynamics and biomechanical properties of human cranium].

The peculiarities of relationships between changes of cerebral blood flow, intracranial liquor dynamics and skull biomechanics in humans were studied in an age aspect. For this aim, a non-invasive method was proposed based on concomitant registration of rheoencephalogram and transcranial dopplerogram and evaluation of relationships between intracranial volume and pulse pressure changes (P-V index). The data obtained were analyzed by pattern-phase computer processing and compared with the blood flow parameters. The investigation was carried out on healthy volunteers of 18-25, 40-50 and 65-75 years of age. It was shown that circulatory-metabolic supplying of human brain was supported by such factors as volume brain blood flow, intracranial liquor dynamics in cooperation with skull biomechanics. The cerebral blood flow decrease at aging could be compensated by increase of the reserve-compensatory abilities of the system of cranial-spinal liquor dynamics.