1. Causes of a ruptured cerebral aneurysm

A. Factors that weaken blood vessel walls

• Long-term high blood pressure (hypertension), which weakens vessel walls.

• Atherosclerosis, which reduces elasticity of arteries.

• Head trauma (rare, but may rupture an existing aneurysm).

• Vascular infections (mycotic aneurysm).

• Smoking (a major risk factor).

• Heavy alcohol use and stimulant drugs (especially cocaine, amphetamines).

B. Congenital or medical conditions associated with aneurysms

• Connective tissue disorders (Marfan syndrome, Ehlers–Danlos).

• Polycystic kidney disease.

• Arteriovenous malformations (AVMs).

• Family history of brain aneurysms.

C. Situations that can trigger rupture

Rupture can occur when blood pressure suddenly increases:

• Straining during bowel movements.

• Intense physical exertion.

• Stress or emotional surges.

• Sexual activity.

• Sudden spikes in blood pressure.

However, many aneurysms rupture during rest or sleep without warning.

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2. Symptoms of a ruptured aneurysm

A rupture causes a subarachnoid hemorrhage (SAH), a neurological emergency.

Most prominent symptom

• A sudden, extremely severe headache
  – often described as “a thunderclap” or “the worst headache of my life,” occurring within seconds.

Other common symptoms

• Severe nausea and vomiting

• Neck stiffness

• Sensitivity to light

• Blurred or double vision

• Altered consciousness: confusion, drowsiness, or deep coma

• Seizures

• Weakness or paralysis on one side of the body

• Unilateral dilated pupil (suggesting nerve compression)

Severe, life-threatening signs

• Immediate loss of consciousness

• Brief breathing arrest

• Bilateral fixed dilated pupils

• Deep coma (GCS < 7)

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3. Warning symptoms before rupture (if present)

About 10–20% of patients may have warning signs hours to days before rupture:

• Unusual or persistent headache

• Blurred vision

• Pain around the eye

• Drooping eyelid

But many cases have no warning signs at all.