Decline In Cerebral Blood Flow Research Articles

Cerebral blood flow in diabetes mellitus: evidence of abnormal cerebrovascular reactivity.

Cerebral blood flow (CBF) was studied at normocapnia and after a challenge with 5% CO2 in 59 diabetic patients and 28 controls. There was a significant age-related decline in CBF in both groups, which suggests that diabetes does not affect the rate of decrease of CBF with age. After CO2 challenge CBF increased in most of the controls; in the patients CBF increased in 23, decreased in 26, and remained stable in 10. Thus the reactivity of cerebral blood vessels in diabetics is altered. Diabetics have diminished cerebrovascular reserve and are thus at increased risk of cerebrovascular disease because they are unable to compensate when necessary with an increased CBF.

Diaschisis with cerebral infarction.

Fifteen patients admitted to Philadelphia General Hospital with acute strokes had repeated measurements of cerebral blood flow measured by the 133Xenon inhalation method. A progressive decline in cerebral blood flow in both hemispheres was observed during the first week after infarction in twelve of these patients. This decline could be partially explained by loss of autoregulation, but could not be correlated with level of consciousness, clinical status of PCO2. This progressive decline in flow in the non-ischemic hemisphere indicates a process more complex than a simple destruction of axonal afferants to neurons as implied by the term diaschisis. The flow changes in the non-ischemic hemisphere are likely caused by a combination of the immediate effects of decreased neuronal stimulation modified by loss of autoregulation, release of vasoactive substances, cerebral edema, and other factors.

Effect of Cobalt-60 Gamma Irradiation on Blood Pressure and Cerebral Blood Flow in the Macaca mulatta

Sixteen Macaca mulatta monkeys were exposed to a single 2500-R dose of cobalt-60 gamma irradiation at a dose rate of 500 R/min. Immediately following irradiation there was precipitous decline in cerebral blood flow. The initial decline was followed by a period of partial recovery within 20 to 30 minutes, with a subsequent slower secondary decrease in cerebral blood flow thereafter. Alterations in cerebral blood flow were accompanied by parallel changes in systemic blood pressure. Following irradiation there was a phase of immediate hypotension followed by transient partial recovery at 20 to 30 minutes. Contributing to the observed decrease in cerebral blood flow following irradiation was an apparent impairment of the normal regulatory function of the cerebral vasculature in maintaining adequate blood flow. The cerebral blood flow decline was of a degree that might be expected to produce impairment of normal CNS function. It occurred at a time during which behavioral incapacitation has been observed follow...