Cerebral Aneurysm and Subarachnoid Hemorrhage
What Is It?
A cerebral aneurysm is a bulging of an artery that supplies blood to the brain. These aneurysms can enlarge over time and are at risk for rupturing. If they rupture then bleeding occurs around the brain, called subarachnoid hemorrhage because it occurs in the space under the arachnoid membrane which covers the brain and spine. Subarachnoid hemorrhage generally occurs suddenly and causes a severe headache and can cause significant neurological injury or death.
The cause of a cerebral aneurysm in most patients is not known. They are generally thought to occur sporadically and develop during a persons life. They are more common with older age and there may be an association with high blood pressure and/or smoking. As the cerebral aneurysm enlarges its risk for rupture increases although aneurysms of any size can potentially bleed. Rarely patients can have multiple aneurysms and there are some familial conditions which can increase the risk for the development of aneurysms.
The cerebral aneurysm itself may or may not cause symptoms. Often they are silent, without overt symptoms. They can occasionally cause headache or other neurological symptoms, particularly if they are larger and putting pressure on surrounding neurological structures (nerves, brain, etc.). Usually, the overt symptoms only occur when the aneurysm ruptures and bleeds. This causes severe, sudden headache and other symptoms.
What Types of Symptoms Are Typical?
When a cerebral aneurysm ruptures, the most common symptom is headache. The headache typically comes on very suddenly and is typically very severe. Patients often describe it as "the worst headache of my life." The headache is usually described as a sharp or stabbing pain. While some patients only experience headache, many have other symptoms as well.
Other symptoms accompanying headache with subarachnoid hemorrhage can include:
- Nausea and/or vomiting
- Photophobia (avoidance of bright light)
- Neck stiffness and/or pain (nuchal rigidity)
- Deterioration or loss of consciousness
In addition to these symptoms, some people suffering a subarachnoid hemorrhage will present comatose or even die before they reach the hospital. In fact, a significant percentage of all subarachnoid hemorrhage present as sudden death.
How Is The Diagnosis Typically Made?
The diagnosis of subarachnoid hemorrhage from rupture of an aneurysm is typically made by three different means. First, the simple history and physical exam can often suggest the diagnosis. If a patient presents with the classic symptoms of a sudden, severe headache, the diagnosis of subarachnoid hemorrhage should be considered.
To further work up such a patient, a CT scan is usually ordered. The CT scan can usually demonstrate the acute blood around the base of the brain, confirming the diagnosis.
Rarely, if the CT scan does not definitively show blood but the patient has all the classic symptoms of subarachnoid hemorrhage, a lumbar puncture (spinal tap) can be performed. A needle is inserted into the spine in the lower back and a sample of cerebrospinal fluid (the water-like fluid that surrounds the brain and spinal cord) is sampled. Normally the CSF has no blood in it. In a patient with subarachnoid hemorrhage there will be considerable blood in the CSF and it will display xanthochromia (a yellow discoloration due to break-down products of hemoglobin from the blood).
To make the diagnosis of a cerebral aneurysm as the cause of the subarachnoid hemorrhage there are another few studies which may be ordered. Classically, an angiogram is used to evaluate the blood vessels to the brain. This study uses a dye injected into the arteries to take x-ray images of the blood vessels. This study is generally considered the gold standard and can demonstrate the exact size, location and configuration of most cerebral aneurysms.
More recently, newer technologies have been used to diagnose aneurysms. A special CT scan called a CT angiogram can be used in some hospitals and good ones have the advantage of a 3-dimensional image of the blood vessels and aneurysm. Special MRI scans, called MRA or MR angiography, can also be used to image the blood vessels although the resolution of this method is not as good as either CTA or classic angiography and can miss small aneurysms.
What Are Some Common Treatments?
Treatment of a cerebral aneurysm, whether it has ruptured or not, are aimed at excluding the aneurysm from the blood circulation so that it cannot rupture or re-rupture. For the majority of aneurysms this is accomplished by one of two ways.
The older, traditional treatment is to clip the aneurysm surgically. The head is opened by a neurosurgeon (opening the skull is called a craniotomy) and the aneurysm and surrounding blood vessels are exposed. A special metal clip is used to close the base of the aneurysm so that blood can no longer get into the aneurysm.
A newer technique which can be used for many aneurysms is called endovascular treatment or "coiling". A catheter is advanced into the arteries from a large blood vessel in the upper leg (the femoral artery). This catheter is maneuvered by x-ray up to the aneurysm where it can be used to deposit metal coils that fill the aneurysm. This helps to fill the space within the aneurysm and cause the remaining space to clot off, preventing blood from filling the aneurysm.
Both of these treatments have their advantages and disadvantages and their applicability may vary depending on the specifics of each aneurysm and patient. Patients should discuss their options with their own treating physicians to determine the best management option for their specific case.
In a patient who presents with a subarachnoid hemorrhage, treatment usually entails many different things. For one, their aneurysm is generally treated as quickly as possible by one of the means described above. Additionally, these patients are generally admitted to an intensive care unit to closely care for them during the acute period after the hemorrhage. The specifics of this treatment will vary depending on the clinical condition of the patient. Most patients are treated to control blood pressure before the aneurysm is protected, to help prevent re-rupture. Some patients may develop hydrocephalus which may require treatment by a ventriculostomy or shunt. Patients who are comatose or have significantly depressed level of consciousness may need to be on a mechanical ventilator. Patients will also be screened for and treated for vasospasm which is a common complication after subarachnoid hemorrhage. Vasospasm is a constriction of the blood vessels to the brain which can cause new neurological injury or stroke.
The long term disability and mortality rates after subarachnoid hemorrhage can be substantial. Those patients who survive the acute period often have a prolonged hospitalization, oftentimes followed by rehabilitation treatments.
Return to the Causes of Headaches page
from the Cerebral Aneurysm page.
Return to the Nervous System Diseases home page.
This site is not intended to offer medical advice. Every patient is different, and only your personal physician can help to counsel you about what is best for your situation. What we offer is general reference information about various disorders and treatments for your education.