Increased intracranial pressure sometimes causes protrusion (herniation) of brain tissue through one of the rigid intracranial barriers (tentorial notch, falx cerebri, foramen magnum). Brain is classified based on the structure through which tissue is herniated.
Transtentorial (uncal) herniation: The medial temporal lobe is squeezed by a unilateral mass across and under the tentlike tentorium that supports the temporal lobe.
Subfalcine herniation: The cingulate gyrus is pushed under the falx cerebri by an expanding mass high in a cerebral hemisphere.
Central herniation: Both temporal lobes herniate through the tentorial notch because of bilateral mass effects or diffuse brain edema.
Upward transtentorial herniation: This type can occur when an infratentorial mass (eg, tumor in the posterior fossa, cerebellar hemorrhage) compresses the brain stem, kinking it and causing patchy brain stem ischemia.
Tonsillar herniation: Usually, the cause is an expanding infratentorial mass (eg, cerebellar hemorrhage), forcing the cerebellar tonsils, through the foramen magnum.
If ICP is increased, intracranial and cerebral perfusion pressure should be monitored, and pressures should be controlled.
Question:
What is the ideal intracranial pressure (ICP) goal that is needed to maintain a proper cerebral profusion pressure of 50-70mm Hg?
Results
#1. What is the ideal intracranial pressure (ICP) goal that is needed to maintain a proper cerebral profusion pressure of 50-70mm Hg?
The goal is to maintain ICP at ≤ 20 mm Hg and cerebral perfusion pressure at 50 to 70 mm Hg. Cerebral venous drainage can be enhanced (thus lowering ICP) by elevating the head of the bed to 30° and by keeping the patient’s head in a midline position.
Measures to control ICP include: Sedation, Hyperventilation, Hydration, Diuretics, Blood pressure (BP) control, Corticosteroids, Removal of cerebrospinal fluid (CSF), Position The patient’s head should be kept in a midline position, and neck rotation and flexion should be minimized. Tracheal suctioning, which can increase ICP, should be limited.
