Brain Aneurysm Symptoms — Warning Signs You Must Never Ignore

Most brain aneurysms are silent until they rupture — but some give warning signs. Knowing them can be life-saving. This is one medical article that everyone should read once.

The Thunderclap Headache — The Most Important Warning Sign

A ruptured brain aneurysm (subarachnoid haemorrhage) classically presents as a sudden, explosive headache — described by patients as "the worst headache of my life" or "like being hit on the head with a hammer." It reaches maximum intensity within seconds, often accompanied by nausea, vomiting, neck stiffness, sensitivity to light, and sometimes loss of consciousness. This is a medical emergency with a 30–40% mortality rate if not treated immediately.

Sentinel Headache — The Warning Bleed

In 10–43% of cases, a small warning bleed (sentinel bleed) occurs days to weeks before the major rupture. This presents as a sudden, severe headache that then resolves. Many patients dismiss this as a migraine. It is not — it is a critical warning that a major rupture may be imminent. Any sudden, unusually severe headache warrants immediate CT scanning.

Symptoms of an Unruptured Aneurysm

Large unruptured aneurysms can press on adjacent brain structures and cause symptoms: double vision or visual loss (aneurysm compressing the optic nerve), a drooping eyelid and dilated pupil (posterior communicating artery aneurysm pressing on cranial nerve III), facial pain or numbness. These symptoms require urgent MRI and neurovascular evaluation.

Who Should Be Screened?

Consider brain aneurysm screening (MRA or CT angiography) if you have: first-degree relatives with brain aneurysms (2+ family members), polycystic kidney disease, previous brain aneurysm, coarctation of the aorta, Marfan's syndrome, or a connective tissue disorder.