What is cerebral hemorrhage? Cerebral hemorrhage is uncontrolled bleeding in the brain. It can occur from an injury or as a result of a leaky or burst blood vessel. This can happen when a blood vessel gets weakened enough that its wall can no longer withstand the pressure of the blood flowing through it. High blood pressure, atherosclerosis (buildup of plaque in artery walls), and amyloid angiopathy (protein deposits in artery walls) can weaken blood vessel walls. Aneurysms, which are bulges in weakened areas, can form when blood vessels are damaged or they can be present at birth. Arteriovenous malformations, which are abnormal connections between arteries and veins that may be present at birth, are another vascular abnormality that can be a site of cerebral hemorrhage. The brain has many blood vessels running through it and around it. If a blood vessel inside the brain bursts, blood can get into the brain tissue and cause inflammation and swelling. If one of the blood vessels on the surface of the brain breaks, blood can collect between the brain and the membranes that surround it (subarachnoid hematoma). This causes pressure on the brain. Both inflammation and pressure can damage the brain. Symptoms of cerebral hemorrhage often come on suddenly. Cerebral hemorrhage is always an emergency and needs to be treated as soon as possible to save as much brain tissue as possible. While some people experience long-term complications of cerebral hemorrhage, others are able to recover completely. Cerebral hemorrhage is always an emergency. Seek immediate medical care (call 911) for serious symptoms, such as severe headache, nausea, numbness or weakness, loss of the ability to see or speak, seizures, or change in level of consciousness or alertness, such as passing out or unresponsiveness.