Cerebral edema is swelling of the brain parenchyma due to excessive fluid accumulation. It may be focal or generalized. Cerebral edema is defined as either vasogenic, cytotoxic, or transependymal. Vasogenic edema occurs when the blood-brain barrier is disrupted and is most often seen with focal lesions such as brain tumors and abscesses. Cytotoxic edema occurs when the blood-brain barrier is intact with impaired cellular metabolism and is most commonly seen with ischemic stroke, toxic exposure, metabolic derangements, and hypoxia. Transependymal edema occurs due to obstructive hydrocephalus and breakdown of the cerebrospinal fluid (CSF)-brain barrier.

Cerebral edema is characterized by blurred vision, intracranial hypertension, headache, and loss of consciousness. Other common signs and symptoms are nausea, vomiting, sudden elevated blood pressure, mental status alteration, and decreased heart rate. It presents a life-threatening medical emergency leading to herniation, coma, and brain death.

Causes include severe brain trauma, ischemic stroke, meningitis, encephalitis, hepatic encephalopathy, brain cancer, diabetic ketoacidosis, eclampsia, or cerebral infarction. It also occurs as a form of high-altitude edema. Cerebral edema may occur in infants and adults.

Management aims to reduce intracranial pressure and excess brain fluid and includes corticosteroids, osmotic agents, diuretics, inotropics and other pharmacotherapy, decompression, and surgery.