PAT 20A/B Chapter Notes - Chapter 9: Cerebral Perfusion Pressure, Subarachnoid Cisterns, Dural Venous Sinuses
23 Jul 2015
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Document Summary
Skull has 3 components: brain tissue, blood & csf. Pressure exerted d/t combined total volume of the 3 components. Equilibrium is maintained by the volume relationship of these 3 within the rigid skull. If the volume of one component increases & the volume from another component is displaced, the total intracranial volume won"t change. If a volume of 1 component changes without a decrease in another, icp elevates. Not applicable in situations in which the skull isn"t rigid (neonates) Intrinsic compensatory mechanisms exist to resist increases in icp. Major compensatory mechanism is displacement of csf into spinal subarachnoid space or basal subarachnoid cisterns, and to a lesser degree by altering production & absorption. Alterations in blood volume occur through compression of cerebral veins & dural sinuses, regional cerebral vasoconstriction/dilation or changes in venous outflow. Brain tissue volume compensates through distention of dura/compression of brain tissue.
