This information is intended to provide an overview of the anatomy of the brain and to help you understand what happens during a ruptured cerebral aneurysm. The anatomy overview will provide the basis for understanding the ruptured cerebral aneurysm repair.
Hemorrhage from a Ruptured Cerebral Aneurysm
What is it?
Hemorrhage is the medical term for bleeding. The rupture of one of the brain's blood vessels can cause bleeding into the subarachnoid space - beneath the arachnoid membrane, on top of the pia mater - and into brain tissue. The bleeding usually stops, at least temporarily, when a clot forms over the ruptured area.
Why does it happen?
The most frequent cause of spontaneous subarachnoid hemorrhage (not due to injury) is the rupture of a small aneurysm, or bulging sac, on one of the blood vessels that supplies the brain (Fig. 3). It is usually impossible to determine why the aneurysm forms and bursts, but the condition is common in adults and may be associated with aging, diabetes, pregnancy, hypertension (high blood pressure), heredity or trauma.
Cerebral aneurysms are usually of three types: saccular with a narrow "neck" (called "berry" aneurysms because of their shape and their tendency to occur in clusters); saccular with a broad base; and fusiform, in which a short section of the artery bulges all the way around (Fig. 4). Each shape determines the degree of difficulty a surgeon faces in attempting to treat the problem.
An aneurysm may rupture spontaneously - even during sleep - and therefore may not be related to the strain of hard work, sexual intercourse or other physical activity.
Although it is not always possible to discover the exact source of bleeding, other causes of spontaneous subarachnoid hemorrhage include arteriovenous malformations, certain types of infections and bleeding disorders.
What symptoms can it cause?
A ruptured cerebral aneurysm at first causes a severe headache, which can be followed by nausea, vomiting, double vision, sensitivity to light, neck stiffness, weakness, memory loss, paralysis, coma or death. The headache is usually of sudden onset and tremendous severity.
How severe the symptoms are and how long they last depend on the amount and location of the bleeding.
What complications can occur from the rupture?
The blood vessels around the aneurysm are irritated by the blood from the hemorrhage and will at times go into a state of spasm, (Fig. 5). This vasospasm ("vaso" meaning vessel) can occur any time after the rupture, usually peaks at seven days following the hemorrhage and resolves within 14 days when the blood has been absorbed by the body. It can increase any or all symptoms. It is the body's own attempt to prevent a second hemorrhage by restricting the flow of blood through the vessels around the aneurysm. Vasospasm thus reduces pressure on the delicate aneurysm but unfortunately also reduces the normal blood supply to parts of the brain.
Ongoing research is being done to discover a medicine that will control vasospasm. As of yet, none has proven very effective, though some medications offer neurological benefit. The mainstay of treatment is aggressive hydration and elevation of blood pressure.
Other complications from subarachnoid hemorrhage, such as hydrocephalus, hematoma (blood clot) and brain swelling involve the brain. But other body systems also can be affected because of the severe nature of the illness. Pulmonary embolus, heart abnormalities and bleeding from an ulcer may cause further complications.
How is it diagnosed?
Several tests are used to confirm the diagnosis of a ruptured cerebral aneurysm. Some are explained in the evaluation portion of this section.
Because cerebrospinal fluid flows within the subarachnoid space, a sample of CSF taken during a spinal tap at the base of the spine will show blood from the hemorrhage. A CT scan will show blood inside the skull and indicate how much bleeding has occurred. To find the source of the hemorrhage, an angiogram is performed.
When is surgery performed?
Surgery is performed only when the patient's condition allows. It is done to place a clip around the "neck" of the aneurysm in an attempt to prevent a second rupture or to relieve pressure on the brain from a large blood clot.
Surgery cannot reverse brain injury already caused by the hemorrhage, which must be treated with rest and rehabilitation. If clipping is impossible, an attempt is made to treat the aneurysm in another way (such as coating it with a plastic wrap, trapping it or coiling it through the groin endovascularly).
What happens afterwards?
Many patients return to normal function after treatment. The condition of the patient before surgery is the most important factor in outcome.
If a neurologic deficit remains, a period of rehabilitation will be necessary to maximize improvement. This process requires that the patient and his family maintain a strong, positive attitude, set small goals for improvement and work steadily to accomplish each goal.