Brain aneurysm symptoms, among them headache behind eyes or between eyes, are extremely rare, but when they occur, they're serious and require quick attention.

When trying to figure out the reason behind a headache, you might find yourself wondering if you’re having brain aneurysm symptoms. Dilated pupils, blurred or double vision, and eye-region pain (a headache behind eyes, a headache between eyes, or a headache above eyes) all could be signs to seek medical attention: They may be brain aneurysm symptoms signaling that a blood vessel in the brain is leaking or is about to rupture. The latter condition is fatal in about 40 percent of cases.

So why do brain aneurysm symptoms occur, and could your headaches (particularly a headache behind eyes) be a warning sign? First, it helps to know what an aneurysm is.

What Is a Brain Aneurysm?

Aneurysms are weak areas in the arteries that bulge outwards to form a balloon. You can develop an aneurysm anywhere in your body, but they are especially common in the aorta, which is the main artery carrying oxygenated blood from the heart into the body. If an aneurysm occurs here, it’s called an aortic aneurysm, and it can develop in the abdomen or the chest area.

It’s less common to develop a brain aneurysm (also called a cerebral aneurysm), but certain risk factors increase your vulnerability. For example, aneurysms are more common in people age 40 and older (particularly women), people with a family history of brain aneurysms, and people who’ve suffered head injuries. High blood pressure and atherosclerosis (hardened arteries) also increase your risk, as do inherited conditions that weaken blood vessels (for example, vascular Ehlers-Danlos syndrome, in which reduced levels of a protein called collagen render body tissues fragile), and blood vessel abnormalities in the brain. Smoking and/or drinking heavily and a history of cocaine abuse also can factor in.

If you fit into any of these categories, it’s important to be aware of which brain aneurysm symptoms might signal a medical emergency.

Stay Alert for These Brain Aneurysm Symptoms

Certain brain aneurysm symptoms can suggest the presence of a large unruptured aneurysm. As noted above, these symptoms include:

• Headaches (particularly headache behind eyes, headache between eyes, and headache above eyes).
• Dilated pupils
• Blurred or double vision

Other brain aneurysm symptoms red-flag a possible rupture. Even though the bleeding from a rupture typically lasts only for a few seconds, it can damage brain cells and increase pressure in the brain, disrupting the flow of oxygen. The pressure also can block the flow of cerebrospinal fluid around the brain, causing a build-up of fluid that further increases damaging pressure on the brain. Increased pressure can result in a coma, brain damage, and/or death.

Even if you survive the immediate aftermath of a rupture, blood vessels in the brain can gradually constrict in the days and weeks afterwards. Called vasospasm, this condition can trigger a stroke. Symptoms:

• Sudden, severe headache
• Sudden onset of blurred or double vision
• Drooping eyelids
• Stiff neck
• Nausea and vomiting
• Sudden weakness and dizziness
• Sudden light sensitivity
• Seizures
• Loss of consciousness