Your Eyes Might Be the First to Know About a Brain Aneurysm

One in 50.

That's how many people in the United States are walking around with an unruptured brain aneurysm — about 6.8 million people, according to the Brain Aneurysm Foundation. Most of them have no idea.

A brain aneurysm is a weak spot in a brain artery that balloons outward, like a thin patch on a garden hose. Most never cause trouble. But when one ruptures, blood spills into the space around the brain — a subarachnoid hemorrhage — and about half the time it's fatal. Roughly 30,000 Americans rupture one every year. That's one every 18 minutes.

I look at eyes for a living, so here's the part that keeps me up at night: sometimes the first warning sign shows up in the eyes.

The droopy eyelid that meant something

A neurosurgeon I follow, Dr. Betsy Grunch, recently shared the case of a 46-year-old mother who felt a pop in her head while lifting weights, followed by the worst headache of her life. In the ER, her neck was stiff — and her right eyelid was drooping, with the pupil on that side blown wide.

That combination told the whole story. She had an aneurysm on the posterior communicating artery — a "PCom" aneurysm — sitting right next to the third cranial nerve, the nerve that lifts your eyelid, constricts your pupil, and moves your eye. The aneurysm was pressing on it.

Here's the rule every eye doctor learns early and never forgets: a painful third-nerve palsy with a dilated pupil is a compressive lesion until proven otherwise. In plain English — if your eyelid droops and your pupil blows and it hurts, think aneurysm, and think fast.

And here's the part that gives me chills: a week earlier, she'd had a smaller headache she chalked up to stress. That was likely a sentinel headache — a small warning leak before the big one. Some data suggests up to half of ruptures are preceded by one. She didn't know. Most people don't.

Know the warning signs

The classic red flags of a rupture:

• A sudden, severe "thunderclap" headache — the worst of your life, peaking within seconds
• Nausea or vomiting
• Stiff neck, sensitivity to light
• Loss of consciousness, seizure, or sudden weakness

A thunderclap headache means calling 911 — even if it starts to feel better. Don't drive yourself. Don't wait for the rest of the list.

And the subtler one, from my side of medicine: a new droopy eyelid with a dilated pupil, especially with pain or headache around the eye. That's an emergency too.

What raises the risk — and what you can change

Smoking and high blood pressure are the two big modifiable risk factors — two things you can do something about today. Family history matters as well: the American Heart Association recommends screening for people with two or more first-degree relatives diagnosed with a brain aneurysm. Aneurysms are more common in women, and most ruptures happen between ages 35 and 60.

The good news buried in all this: most aneurysms are treatable, and many small ones are simply watched with periodic scans. Finding one isn't an automatic trip to the operating room — it's information, and information is the whole game.

Why I'm writing about this

Because the eyes are the only place in the body where we can look directly at blood vessels and nerves without cutting anything open — and because every so often, the eyes file the first report. A droopy lid. A pupil that won't constrict. Details that seem small until you know what they mean.

September was Brain Aneurysm Awareness Month, but awareness doesn't expire. Know the thunderclap headache. Know your blood pressure. Know your family history. And know that your eyes might be trying to tell you something,

Sources: Brain Aneurysm Foundation, statistics and facts (bafound.org); case via Betsy Grunch, MD, #SundayCaseStudy on LinkedIn.

Author

Paddy Kalish OD, JD and B.Arch Author and Blogger