3.16
Intracranial pressure, or ICP, means the pressure inside the skull. Normal ICP in lying adults is 7 to 15 mmHg.
The rigid and nonexpandable cranium houses three primary components: brain tissue, cerebrospinal fluid, and blood.
According to the Monro–Kellie doctrine, a typical adult's total intracranial volume is about 1,700 mL, consisting of brain tissue, which is 80%, blood, which is 10%, and CSF, which is 10%.
If one component increases and another does not decrease, ICP rises.
Causes of increased ICP include head injury, intracranial hemorrhage, and large ischemic stroke, as well as infections, such as meningitis.
Other contributing factors for increased ICP include space-occupying lesions, such as brain tumors, and disturbances in CSF dynamics, such as impaired CSF reabsorption in hydrocephalus or increased CSF production in choroid plexus tumors.
Intracranial hypertension is a sustained elevation of intracranial pressure (ICP) above 22 mm Hg. In supine adults, normal ICP is ~7–15 mm Hg.
The rigid, nonexpandable cranium contains three components—brain tissue, blood, and cerebrospinal fluid (CSF)—that total ~1,700 mL in a typical adult: 1,400 mL brain (~80%), 150 mL blood (~10%), and 150 mL CSF (~10%). According to the Monro–Kellie doctrine, total intracranial volume is effectively fixed. When one component expands, CSF and venous blood are displaced to compensate; once that reserve is exhausted, ICP rises steeply.
Causes by compartment
Brain compartment — increased tissue volume (edema or mass effect)
CSF compartment
Vascular compartment — increased blood volume or pressure
Intracranial pressure, or ICP, means the pressure inside the skull. Normal ICP in lying adults is 7 to 15 mmHg.
The rigid and nonexpandable cranium houses three primary components: brain tissue, cerebrospinal fluid, and blood.
According to the Monro–Kellie doctrine, a typical adult's total intracranial volume is about 1,700 mL, consisting of brain tissue, which is 80%, blood, which is 10%, and CSF, which is 10%.
If one component increases and another does not decrease, ICP rises.
Causes of increased ICP include head injury, intracranial hemorrhage, and large ischemic stroke, as well as infections, such as meningitis.
Other contributing factors for increased ICP include space-occupying lesions, such as brain tumors, and disturbances in CSF dynamics, such as impaired CSF reabsorption in hydrocephalus or increased CSF production in choroid plexus tumors.
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