Brain Swelling (Cerebral Oedema): Causes, Consequences, and Treatment

The human brain sits within a rigid skull — a closed box. Any process that increases the volume inside this box raises intracranial pressure (ICP). As ICP rises, blood flow to the brain is compromised, and eventually brain tissue is forced downward through the base of the skull (herniation) — a catastrophic event that causes rapid death or permanent brain damage unless reversed immediately. Brain swelling (cerebral oedema) is one of the most important and dangerous causes of raised ICP.

Causes of Brain Swelling

Vasogenic oedema: Breakdown of the blood-brain barrier — the tight junction system that keeps fluid out of brain tissue. Causes: brain tumour (both primary and metastatic — tumours produce factors that disrupt the BBB); abscess; severe meningitis or encephalitis; major ischemic stroke. The oedema surrounds the lesion like a halo on CT/MRI.

Cytotoxic oedema: Swelling within the brain cells themselves due to cellular energy failure. Occurs in: ischemic stroke (cells cannot maintain their ion pumps; water floods in); cardiac arrest (global ischemia); severe hypoglycaemia; traumatic brain injury. This type is largely irreversible — the cells are dying.

Hydrocephalus: Accumulation of cerebrospinal fluid — either due to obstruction of its flow (obstructive hydrocephalus — tumour blocking the ventricular system) or impaired reabsorption.

Symptoms of Rising Intracranial Pressure

Classic triad (Cushing's triad — a late and ominous sign): hypertension + bradycardia + irregular breathing. Earlier signs: progressive headache (worst on waking); repeated vomiting (projectile, without nausea); decreasing level of consciousness; one pupil dilating and becoming unreactive (third nerve compression — sign of imminent herniation).

Management

Head elevation to 30°; IV mannitol or hypertonic saline (draws fluid out of the brain); controlled hyperventilation (temporarily reduces CO2 and constricts cerebral vessels); dexamethasone (specifically for vasogenic oedema around tumours and abscesses); emergency decompressive craniectomy for large strokes or traumatic brain injury. For neurological consultation: Sri Anand CNC, Chanda Nagar, Hyderabad. Call +91 90633 66983.