Intracerebral Hemorrhage

A Balloon Pump Inside a Rigid Box

Your skull is a rigid plastic container—it cannot stretch. Inside sits the brain tissue (the balloon's rubber), blood vessels (thin tubes carrying fluid), and cerebrospinal fluid (the air pumping in). Normally, the pump adds air slowly and the balloon expands evenly. But when one tube ruptures, air (blood) floods out in a jet and collects in a pocket, pushing the balloon sideways and compressing its neighbors. The box (skull) cannot give way, so pressure inside climbs. First, the pump (your body) tries to squeeze out some air (CSF) to make room, but that only works a little. Soon the swollen pocket squashes the balloon's vital control center (the brainstem—the place that keeps you breathing and awake), and the whole system collapses. The rupture is like a weakened tube—years of high pressure (hypertension) or buildup of gunk (amyloid) thins the walls until they split.