What Causes Brain Aneurysms? Hypertension, Smoking and Other Risk Factors

In haemorrhagic stroke, neurons aren't 100% dead — there's cytotoxic oedema, but if we can remove the blood and relieve the pressure on the brain, neurons can recover function. Our primary goal is to save the patient's life first; the first week to ten days after the bleed is life-threatening, so all effort goes into preventing death and disability, and neurological recovery happens over time through rehabilitation. That's different from ischemic stroke, where we're reversing the deficit on the table itself — rescuing neurons at the brink of death and restoring function immediately.

Not all intracranial haemorrhages require surgical evacuation — most are managed medically. When the bleed is causing raised intracranial pressure, because the brain is inside a closed skull and any extra volume risks herniation, we have to evacuate it. There are several techniques — minimally invasive surgery, stereotactic drainage, or open decompressive surgery — and that's the neurosurgeon's domain. Our endovascular role is in identifying and occluding the underlying vascular cause, the aneurysm or AVM, that caused the bleed in the first place.

Think of it like a blocked drainage system under a city. A surgeon's approach is to dig down from outside to reach the blockage. Our approach is to enter the drainage system from where it begins and navigate a map through the system to the blockage, clearing it from within — you don't have to dig the ground. Access is through a needle puncture in the groin or wrist, and from there the catheters track through the blood vessels all the way to the brain.

Age is not a criterion for us. We have treated patients in their 90s and even at 100 years of age and seen them recover. Age alone is never a reason to withhold intervention.

The key risk factors are hypertension and smoking. Blood hits the vessel wall repeatedly, the wall weakens and bulges into an aneurysm, and the body tries to repair itself — but if blood pressure is chronically elevated, or tobacco smoke is weakening the vessel wall, or there's an underlying genetic factor causing weak collagen, that repair mechanism gets overwhelmed and the aneurysm develops over time. This is different from AVMs, which are congenital and present from birth — aneurysms are acquired lesions that develop over a lifetime.

AVMs are congenital lesions present since birth, while aneurysms are acquired: they develop gradually over a person's lifetime as a consequence of factors like hypertension and smoking.

Yes. An underlying genetic factor involving weak collagen in the vessel wall can also predispose a person to aneurysm formation, compounding the effect of chronic hypertension and smoking.