What is a subarachnoid hemorrhage?
Subarachnoid hemorrhage (SAH) refers to bleeding within the subarachnoid space, which is the area between the brain and the tissues that cover the brain.
The subarachnoid space is the space where the cerebrospinal fluid circulates, and it’s responsible for protecting your brain from injury by serving as a cushion. A hemorrhage in this space can cause a coma, paralysis, and even death.
This condition can occur quickly, and is often the result of head trauma. The key to survival is immediate medical intervention. Call a doctor or 911 as soon as possible if you or someone you know has the symptoms of SAH.
This life-threatening condition is also rare. According to the Brain Aneurysm Foundation, SAH accounts for between 0.01 and 0.08 percent of visits to the emergency room.
Symptoms of SAH
When SAH develops, it has several symptoms. The main symptom is a sudden, severe headache, which is more intense at the base of the skull. It is often described as the worst headache people have ever experienced. Some people may even feel a popping sensation in their head before the hemorrhage begins.
You may also have:
- neck pain
- numbness throughout your body
- shoulder pain
- sensitivity to light
- decreased vision
- double vision
- rapid loss of alertness
The symptoms of SAH come on suddenly, and you may lose consciousness quickly. Seek emergency medical attention right away if you experience any of these symptoms combined with a severe headache.
Causes of SAH
SAH can occur spontaneously, or as a result of head trauma. Spontaneous SAH is often related to brain aneurysms, which are abnormalities within the brain’s arteries. The most common cause of primary SAH is a berry aneurysm. It’s called a berry aneurysm because it forms a cluster of sac-like pouches in a cerebral vessel that looks like a cluster of berries. These aneurysms swell up and weaken the walls of the arteries over time.
When an aneurysm erupts, it quickly bleeds and forms a clot. This condition is responsible for most SAH cases. Aneurysmal hemorrhage may occur at any age, but it’s most common between age 40 and 65. Brain aneurysms are more common in women, in smokers, and in those with high blood pressure. In some cases, trauma to the brain during an injury can cause aneurysms and result in a subarachnoid hemorrhage.
Other causes of SAH include:
A serious head injury, such as one that occurs in a car crash or when an older person falls and hits their head, can also lead to an SAH.
Risk factors for SAH
SAH can occur at any age, and some people are even born with cerebral aneurysms that can lead to this condition. According to the Internet Stroke Center, women are more likely than men to develop brain aneurysms, and thus SAH. Smoking and high blood pressure can also increase your risk of developing an aneurysm. Drug use, particularly methamphetamine and cocaine, dramatically increase the risk of not only developing an aneurysm, but having SAH.
One in 50 people is estimated to have an unruptured aneurysm in the United States. You should talk to your doctor about your risk if you have a history of brain aneurysms.
If you have aneurysms, it’s important to see your doctor regularly to determine your risk for hemorrhaging — before SAH develops.
SAH is often detected during a physical exam. Your doctor may notice that you have a stiff neck and vision problems. The history of the sudden worst headache of your life also makes SAH more likely. This combination often leads to a diagnosis of SAH. You’ll need more testing to find out the severity of the hemorrhage so that you can get proper treatment.
First, your doctor may conduct a CT scan of the head to look for bleeding in your skull. If the results are inconclusive, the doctor may use a contrast dye during the procedure.
Other tests include:
- an MRI scan, which uses radio waves to get clear, detailed images of the brain
- a cerebral angiography, which uses an X-ray and injected dye to detect blood flow in the brain
- a transcranial ultrasound, which detects blood flow in the arteries within the brain
- lumbar puncture to see if blood cells are found in the cerebrospinal fluid
This condition is often misdiagnosed because 73 percent of people don’t get scans.
Rapid treatment is important to save your life and reduce the possibility and extent of brain damage. Bleeding and pressure may build up in the brain, leading to coma and additional brain damage. This pressure needs to be alleviated by medications or a procedure to drain some of the cerebrospinal fluid. Second, the cause of the bleeding needs to be identified and treated, as new bleeding from the same aneurysm can frequently occur without treatment. Surgery is performed to clip, or close, the aneurysm and stop future bleeding.
If your aneurysm is being clipped, a craniotomy is performed and the aneurysm is closed. A craniotomy involves opening the skull to expose the area of involvement. A technique called endovascular coiling may also be used to reduce the risk of further bleeding.
If SAH causes a coma, treatment will include appropriate life support with artificial ventilation, protection of the airways, and placement of a draining tube in the brain to relieve pressure.
If you don’t lose consciousness from the SAH, you’ll still be given strict instructions to prevent post-treatment coma. Bed rest is standard for people recovering from this condition. Your doctor will also ask you to refrain from straining your body or bending over. These actions can increase the pressure on your brain.
Your doctor may prescribe medications to:
- regulate blood pressure with medication through an IV
- prevent artery spasms with nimodipine
- relieve severe headaches with painkillers and antianxiety medications
What are the complications of SAH?
Even after SAH treatment, you may be at risk for related complications. The most common complication is called repeated bleeding. This happens when a rupture that has healed itself ruptures again. Repeated bleeding can increase your risk of death. Comas due to SAH can also eventually lead to death.
In some cases, people may experience seizures or strokes following treatment.
How can I prevent SAH?
The only way to prevent this condition is to identify potential problems within the brain. Early detection and, in some cases, treatment of a brain aneurysm can prevent a subsequent hemorrhage in the subarachnoid space.
What is the long-term outlook for SAH?
SAH is a serious condition that can frequently be fatal. The recovery period is long, and you may be at a higher risk of complications if you’re older or have poor overall health.
The earlier you seek emergency medical care, the better your chances of survival.