When an Aneurysm Bleeds

When an Aneurysm Bleeds

What happens to the brain when an aneurysm bleeds? In most cases, the bleeding stops quickly. However, if blood that has leaked touches brain cells, the cells may be damaged. Blood in the cerebrospinal fluid increases pressure on the brain. Leaked blood may also touch nearby arteries, which may cause these arteries to narrow. 

Damage to Brain Cells

Blood from an aneurysm can leak into the CSF in the space around the brain (the subarachnoid space). The pool of blood forms a clot, called a hemotoma. Blood can irritate, damage or destroy nearby brain cells. This may cause problems with body functions or mental skills. 

Fluid Buildup in the Brain

Blood from a torn aneurysm can block CSF circulation. This can lead to fluid buildup and increased pressure on the brain. The open spaces in the brain (ventricles) then enlarge. This problem is called hydrocephalus. It can make a patient lethargic, confused or incontinent. Fluid may also build up in the brain after surgery. To stop fluid buildup, a drain may be placed in the ventricles. This removes leaked blood and trapped CSF. 

Narrowing of Nearby Arteries

An artery may narrow if leaked blood touches it. This response, called vasospasm, may happen up to 14 days after an aneurysm bleeds. Vasospasm can decrease blood needed in other parts of the brain. It can be fatal. To treat vasospasm, the patient's blood pressure and fluid intake are increased. This increases the force of the blood and widens the artery.