Brain Aneurysm: Symptoms, Causes, Diagnosis & Treatment

Updated in February 2023

A brain aneurysm consists of a dilation of a blood vessel that takes blood to the brain. When this happens, the dilated part will stretch and have a thinner wall, which increases its risk for rupturing. When a brain aneurysm ruptures, it causes a hemorrhagic stroke, which can be life-threatening depending on the amount of bleeding. 

In most cases, intact brain aneurysms do not cause any symptoms. This is why they are usually only discovered after they burst. A ruptured brain aneurysm causes symptoms like a very intense headache that can come on suddenly or gradually, and many patients also report a "hot" head, or a sensation of "emptying" in the head. 

An intact brain aneurysm is treatable with surgery, but generally the doctor will prescribe treatment to decrease the chances of a rupture. Surgery is usually indicated for brain aneurysms that have already ruptured, but it can be recommended for specific aneurysms based on their location and size.

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Main symptoms

Intact brain aneurysms normally do not cause any symptoms and are only found after an extensive head or brain assessment, or after it has ruptured. Some people will present with more specific signs, like constant pain behind the eyes, dilated pupils, double vision or face tingling. 

Symptoms commonly emerge only after the aneurysm has ruptured or if it is emptying. In these cases, symptoms are similar to those of a hemorrhagic stroke, which include: 

  • Very intense and sudden headache that worsens with time
  • Nausea and vomiting
  • Stiff neck
  • Double vision
  • Seizures
  • Fainting 

If these symptoms emerge or if you suspect you may have a ruptured brain aneurysm, you should seek medical attention immediately or call 911. 

Other, less minor, health conditions (like a migraine) can present with similar symptoms. If you have a frequent intense headaches, you should see your family doctor or a neurologist to identify the underlying cause and start treatment as necessary. 

Possible causes

The exact causes of why brain aneurysms develop are still not totally known, although there are some factors that seem to increase the risk for aneurysms. These include: 

  • Smoking 
  • Uncontrolled hypertension
  • Drug use, especially cocaine 
  • Excess alcohol intake
  • Positive family history

In addition, some illnesses chronic and/or genetic illnesses are also associated with a higher risk for an aneurysm, like PCOS, aortic dissection and cerebral malformation.

Confirming a diagnosis

Generally, to confirm the presence of a brain aneurysm, the doctor will order diagnostic imaging to visualize the brain structures and identify any dilation in the blood vessels. The most common imaging tests are MRI, CT scans and cerebral angiography. 

Treatment options

Treatment for brain aneurysms can very depending not only on the patient’s health history, but also the size of the aneurysm and whether it is actively bleeding. The most common treatments include: 

1. Intact brain aneurysm

Most times, doctors opt to leave an intact aneurysm alone, as the risk for bleeding during surgery is very high. The doctors will regularly monitor the aneurysm size instead to ensure it is not increasing in size. 

Medications can be prescribed to relieve symptoms. Acetaminophen or ibuprofen can help to reduce headaches, like levetiracetam can help to manage seizures. 

In some cases, the neurologist may still opt to perform endovascular surgery to insert a stent. This can prevent the rupture of an aneurysm, but it is a very delicate and risky procedure that requires informed consent of the patient. 

2. Ruptured brain aneurysm

Ruptured brain aneurysms are considered to be a medical emergency, which require immediate medical attention in a hospital. Surgery will usually be performed to close the vessel and control bleeding. Prompt treatment leads to a decreased bleeding and a decreased chance of lifelong complications. 

Possible complications 

A brain aneurysm can cause bleeding into the brain (an intracerebral hemorrhage) or into the meninges that line the brain (a subarachnoid hemorrhage).

Some patients may not experience any complications after an aneurysm, while others may have neurological changes, similar to a post-stroke patients. Some complications include difficulty raising an arm, difficulty speaking or slow speech. People who have had an aneurysm in the past have a greater risk for developing another one.