RESUMEN
Biomechanical properties of the human skull affect its dynamic tensility (pliability, compliance) by changes of intracranial volume and pressure (deltaV/deltaP). The goal of this study is to substantiate a possibility of noninvasive and dynamic evaluation of cranial compliance. The transcranial dopplerogram of middle cerebral artery and hemispheric bioimpedance were synchronously recorded, which represent information about pulsative changes of intracranial pressure and volume, respectively. The parameters were recorded at rest and during adequate hemo- and liquorodynamic tests in different age groups--20-30, 40-50, and 70-85 years. As compared with the young group, a decrease of the cranial compliance in the intermediate age group was revealed due to an observed increase if rigidity of skull bones and ligaments, which indicates a decrease of stability of the intracranial circulatory system. However, in the group of 70-85 years the compliance rose again due to an enlargement of intracranial liquor spaces and facilitation of liquor circulation inside the intracranial cavity; this can be suggested to be a compensatory mechanism for supporting the adequate brain circulatory-metabolic state.
Asunto(s)
Envejecimiento/fisiología , Cráneo/anatomía & histología , Adulto , Anciano , Anciano de 80 o más Años , Fenómenos Biomecánicos , Suturas Craneales/anatomía & histología , Suturas Craneales/fisiología , Humanos , Presión Intracraneal , Persona de Mediana Edad , Respiración , Cráneo/fisiología , Adulto JovenRESUMEN
We evaluated increases in local cerebral blood flow (LCBF) localized to single activated cortical columns by H2 clearance methods. The rat whisker-barrel cortex is a model for cortical function and neural processing in active explorative behaviors. Up to four 30-40 microns Pt wire electrodes were inserted in or near the rat whisker-barrel cortex. Electrode positions were mapped by postmortem histology. H2 was generated electrochemically by constant current from one electrode and detected by one or more other electrodes 300-500 microns away. Changes in LCBF produced inverse changes in PH2. Shifts during steady H2 generation were calibrated against standard H2 inhalation clearance curves at rest and during inhalation of 7.5% CO2 for 1 min for quantitative estimates of LCBF. Contralateral whisker stimulation at 3 Hz, 1 min duration and delivered every 2 min produced the largest increases in LCBF. LCBF responses were detected in approximately 1 s. Stimulation of single whiskers produced the largest responses when an electrode was in the corresponding barrel. These results indicate that increased neural activity in a single cortical column produces blood flow responses primarily in that column.
Asunto(s)
Circulación Cerebrovascular/fisiología , Corteza Somatosensorial/irrigación sanguínea , Corteza Somatosensorial/fisiología , Vibrisas/fisiología , Animales , Electrodos Implantados , Complejo IV de Transporte de Electrones/metabolismo , Femenino , Flujometría por Láser-Doppler , Masculino , Estimulación Física , Ratas , Ratas Wistar , Flujo Sanguíneo Regional/fisiologíaRESUMEN
The local cerebral blood flow (LCBF) and cerebrovascular reactivity to CO2 inhalation test were studied in rabbits after experimental local brain lesions. A decrease of the LCBF and cerebrovascular reactivity was observed in the grey and white matter surrounding the traumatic focus at the distance of about 15 mm, being minimal on the 3rd-5th days followed by normalizing by the 10th-14th days after lesions. The cerebrovascular reactivity was found to be a valuable prognostic parameter to assess the functional restoration of the brain.
Asunto(s)
Lesiones Encefálicas/fisiopatología , Encéfalo/fisiopatología , Animales , Vasos Sanguíneos/fisiopatología , Encéfalo/irrigación sanguínea , Corteza Cerebral/irrigación sanguínea , Corteza Cerebral/fisiopatología , Chinchilla , Flujo Sanguíneo RegionalRESUMEN
Studies in cats and in neurosurgical patients reveal that intraskull pressure, blood volume and total brain blood flow depend on the same factors, to a different extent though. This is determined by structural--functional organization of the intraskull circulation system, the analysis of which revealed a scheme of functional interrelationships among volumes and pressures of fluid media in the closed skull space. The features of interrelationships are not rigid and can have their own specifics in concrete situations.
Asunto(s)
Volumen Sanguíneo , Encéfalo/irrigación sanguínea , Presión Intracraneal , Animales , Gatos , Presión Venosa Central , Arterias Cerebrales/fisiología , Humanos , Pletismografía , Conejos , Flujo Sanguíneo Regional , Vasodilatación , Venas/fisiologíaRESUMEN
The functional stability of cerebral circulation involves its ability to resist against external influences and is based on the cerebral vessels reactivity. Objective methods for evaluation of this reactivity are proposed using standard and specific functional loads. The indices of intracranial and systemic hemodynamics were recorded in experimental animals, healthy humans and patients with head injuries during postoperative period. The dynamics of cerebral vessel reactivity was found to depend on the body functional state.
Asunto(s)
Lesiones Encefálicas/fisiopatología , Circulación Cerebrovascular , Animales , Gatos , Humanos , Lactante , Pletismografía de Impedancia , Postura , Presión , ConejosRESUMEN
The feature of correlation between functional activity of the brain tissue and structural-functional characteristics of the vascular system after sensory deprivation by the removal of whiskers in newborn animals were studied in nembutal-anaesthetized rats in comparison to the animals under d-tubocurarine with local anesthesia. It has been shown that there are major changes of EP parameters and ECoG in the sensory-deprived brain area and diminution of brain cortex thickness. Changes in the vascular system are mainly structural, what are revealed as disorganization in angioarchitecture of radial arteries. At the same time, differences in the blood circulation intensity are found in d-tubocurarine animals only. The largest volume of the local blood circulation is observed in intact hemisphere of sensory-deprived animal. Thus, it can be concluded that sensory-deprived model is the alternative to the ischemia model. This model can be used in studies of physiology of brain blood circulation, and the "structure-function" correlation, in particular.
Asunto(s)
Privación Sensorial/fisiología , Corteza Somatosensorial/fisiología , Animales , Animales Recién Nacidos , Estimulación Eléctrica/métodos , Electroencefalografía , Electrofisiología , Femenino , Masculino , Ratas , Ratas Wistar , Corteza Somatosensorial/irrigación sanguínea , Vibrisas/fisiologíaRESUMEN
The development of cortical cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) were studied in Wistar rats during early postnatal ontogenesis, in groups aged 2-5, 6-8, 9-11, 12-15, 16-18 and 19-25 days. CBF was measured polarographically using inhaled hydrogen clearance method, with platinum electrodes inserted into parietal cortex. At the mentioned age periods, CBF and its percentage of adult level averaged as 38 (21%), 81 (45%), 142 (78%), 85 (47%), 110 (61%), and 118 (65%) ml/100 g/min, respectively. Hence, during the early postnatal ontogenesis CBF increased gradually, however, it did not reach the adult level up to the end of the first month. CBF peak at 9-11 days period is suggested as a result of sharp rise of the brain vessels growth. CVR was assessed as the percentage of CBF increase after standardized 5% CO2 inhalation test. At the above age periods, CVR was found to bi 26, 33, 36, 41, 44 and 31% respectively, and was similar to adult rat CVR of 36%. The conclusion was drawn that regulatory mechanisms of adequate responses of brain vasculature to chemical metabolic factors are well developed already at the very beginning of postnatal life.
Asunto(s)
Envejecimiento/fisiología , Encéfalo/irrigación sanguínea , Circulación Cerebrovascular/fisiología , Animales , Animales Recién Nacidos , Encéfalo/crecimiento & desarrollo , Electrodos Implantados , Polarografía , Ratas , Ratas WistarRESUMEN
The authors discuss a new method for measuring the overall cerebral blood flow in man from analysis of the hydrogen clearance curves recorded in the internal jugular vein with a sounding platinum electrode. The hydrogen clearance curves are polyexponential in character and for calculating the blood flow it is therefore necessary to use the stochastic method. The use of the "initial inclination" method is also admissible in proximate curve analysis. The values of the overall cerebral blood flow in patients with craniocerebral injury measured by the method suggested are in agreement with the data in the literature.
Asunto(s)
Circulación Cerebrovascular , Hidrógeno , Neurofisiología/métodos , Humanos , Venas YugularesAsunto(s)
Adaptación Biológica , Arvicolinae/metabolismo , Corteza Cerebral/metabolismo , Hipoxia Encefálica/metabolismo , Consumo de Oxígeno , Enfermedad Aguda , Animales , Corteza Cerebral/irrigación sanguínea , Femenino , Conservantes de Alimentos/farmacología , Conservantes de Alimentos/toxicidad , Hipoxia Encefálica/inducido químicamente , Masculino , Ratas , Ratas Wistar , Nitrito de Sodio/farmacología , Nitrito de Sodio/toxicidad , Especificidad de la EspecieAsunto(s)
Encéfalo/metabolismo , Conservantes de Alimentos/toxicidad , Hipoxia-Isquemia Encefálica/metabolismo , Metahemoglobinemia/metabolismo , Consumo de Oxígeno , Nitrito de Sodio/toxicidad , Enfermedad Aguda , Animales , Encéfalo/irrigación sanguínea , Encéfalo/patología , Conservantes de Alimentos/administración & dosificación , Hipoxia-Isquemia Encefálica/inducido químicamente , Hipoxia-Isquemia Encefálica/patología , Masculino , Metahemoglobinemia/inducido químicamente , Metahemoglobinemia/patología , Consumo de Oxígeno/efectos de los fármacos , Ratas , Ratas Wistar , Nitrito de Sodio/administración & dosificaciónRESUMEN
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.
Asunto(s)
Líquido Cefalorraquídeo/fisiología , Cráneo/anatomía & histología , Cráneo/fisiología , Adulto , Femenino , Humanos , Masculino , Persona de Mediana EdadAsunto(s)
Circulación Cerebrovascular/fisiología , Animales , Vasos Sanguíneos/anatomía & histología , Capilares/anatomía & histología , Corteza Cerebral/anatomía & histología , Corteza Cerebral/irrigación sanguínea , Electroquímica , Microcirculación/fisiología , Ratas , Ratas Wistar , Vibrisas/fisiologíaAsunto(s)
Periodicidad , Cráneo/fisiología , Adaptación Fisiológica , Adolescente , Adulto , Encéfalo/irrigación sanguínea , Medios de Contraste , Impedancia Eléctrica , Electrodos , Humanos , Imagen por Resonancia Magnética , Persona de Mediana Edad , Movimiento/fisiología , Pletismografía de Impedancia/instrumentación , Pletismografía de Impedancia/métodos , Radiografía , Valores de Referencia , Cráneo/anatomía & histología , Cráneo/diagnóstico por imagen , Factores de Tiempo , Grabación de Cinta de Video/instrumentación , Grabación de Cinta de Video/métodosAsunto(s)
Encéfalo/irrigación sanguínea , Encéfalo/fisiología , Periodicidad , Adolescente , Adulto , Animales , Velocidad del Flujo Sanguíneo , Impedancia Eléctrica , Humanos , Hipertensión Intracraneal/diagnóstico por imagen , Hipertensión Intracraneal/fisiopatología , Hipertensión Intracraneal/terapia , Arteria Cerebral Media , Medicina Osteopática , Ratas , Ultrasonografía Doppler TranscranealRESUMEN
In the paper, the mechanism of forming of rhythmic slow-wave fluctuations in craniospinal cavity was investigated. In five young healthy persons, at rest and under voluntary respiration arrest test, the bioimpedansograms of head and lumbosacral part of vertebral column were synchronously registered as these recordings reflect the changes of relationships between blood/CSF volumes in cranial and lumbosacral regions, respectively. The recordings were subjected to frequency and spectral computer analysis (PC Macintosh G-4, Chart 5.2. software). The rapid (pulsatile) as well as slow and counter-directed waves (frequency 6-10 cycles/min) of these processes were revealed in cranial and lumbosacral regions. The data obtained suggest the CSF dynamic concept of origin of the craniosacral rhythm. The pulse and slow-frequency oscillations of the cerebral vessels tone initiate corresponding intracranial pressure waves, and the latter are the motivating forces for to-and-fro CSF shifts in caudal direction. This mechanism is accompanied by tonic contractions of lumbar muscles and sacrum movements, and it is manually perceptible as a craniosacral rhythm.
Asunto(s)
Relojes Biológicos/fisiología , Encéfalo/fisiología , Canal Medular/fisiología , Adulto , Femenino , Humanos , Masculino , PletismografíaRESUMEN
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.