Volume and pressure in the craniospinal axis.

Raised intracranial pressure is common in neurosurgical practice, but the clinical effects are variable. The factors which initiate intracranial hypertension are now fairly well established; the extent of the increase of intracranial pressure produced by any combination of these factors is a function of the volume-pressure status of the patient at that particular time and may be expressed in terms of brain clastance. The effects of raised intracranial pressure on the function of the brain are mediated through both changes in cerebral blood flow and brain shift or herniation. Understanding of these principles helps in selection of effective therapy for raised intracranial pressure. Ideal clinical management of raised intracranial pressure should be directed toward the identification of those situations in which intracranial pressure may become increased and should attempt to prevent intracranial hypertension before it actually occurs.