Cerebral edema (brain swelling) is an “aftershock” of severe traumatic brain injury. Caused, primarily, by vasogenic edema, it usually peaks 48 to 72 hours after the injury. By itself cerebral edema could be detrimental and cause a significant deterioration in the patient’s condition.

The skull is a rigid structure with limited space within it. Once the brain starts expanding within the skull, secondary damage to the brain can occur, primarily, via vascular compromise.

The image above demonstrates the consequences of cerebral edema: loss of white-gray matter differentiation, loss of cerebral sulci, compressed ventricles. You can also see the brain is, literally, bulging out through the craniotomy defect.

The pressure inside the skull, in the patient with a head injury, should be closely monitored. Ventricular drains are being used to monitor the intracranial pressure (ICP) and administer therapeutic interventions like draining the cerebrospinal fluid (CSF) to decrease pressure in the brain. Medications, primarily osmotic diuretics, could also be use to alleviate elevated ICP.

Several studies have shown the benefit of decompressive craniectomy – removing part of the patient’s skull to make more room for the injured brain to expand.