A subarachnoid hemorrhage occurs when there is bleeding between the brain and the subarachnoid space surrounding it. Most cases present with a sudden and severe headache. It's also possible for the headache to cause vomiting, nausea, and loss of consciousness. In most cases, the bleeding occurs when an aneurysm in the brain ruptures. An aneurysm is an abnormal bulge that forms in a blood vessel. Some aneurysms can be treated before they rupture, while others can only be monitored. The bleeding can sometimes also be a result of trauma and injury. In rarer cases, other health issues and blood vessel problems can cause this type of bleeding. Abnormal tangles of blood vessels called arteriovenous malformations can cause this bleeding in the brain.
Surgical clipping is used to treat aneurysms, which are abnormal bulges in the wall of an artery, and sometimes this procedure is done as a preemptive measure to keep the aneurysm from causing bleeding. However, the procedure is often done as part of a treatment and damage control after the aneurysm has already caused bleeding. By themselves, aneurysms often cause no symptoms. In fact, many individuals may not be aware they have an aneurysm at all. But the larger an aneurysm becomes, the thinner the walls of the artery are stretched. It can become thin enough to rupture or leak, which can then lead to a subarachnoid hemorrhage. During a surgical clipping procedure, a neurosurgeon will open the patient's skull and put a clip across the aneurysm's neck. This keeps more blood from entering it, which in turn prevents or stops existing bleeding. It also prevents the aneurysm from growing larger. The main goal of the surgery is to keep blood from flowing into the aneurysm without blocking off any of the small arteries near it.