How Severe Does Carotid Stenosis Need to Be Before It Needs Treatment?

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.

We're usually talking about narrowing at the carotid bifurcation in the neck, where the common carotid artery splits into the external carotid, supplying the face, and the internal carotid, supplying the brain. Stenosis of 50% or more on catheter angiography, or 60% or more on non-invasive imaging like CT or MR angiography, is considered significant and needs treatment. When we say severe stenosis, we mean 70% to 99% narrowing.

We work as a multidisciplinary team with a very respectful relationship with our neurosurgical colleagues. For aneurysms where both approaches are feasible, endovascular coiling is preferred under current guidelines, but we don't impose that on patients. We hold a multidisciplinary meeting, review the morphology together, discuss which endovascular option — coil, stent-assisted coil, or flow diversion — is most appropriate, and then meet the patient's family and explain the complexity, risk, and cost of each option in full so they can make an informed decision.

We need awareness at every level, not just among medical professionals but in the community, about the FAST acronym — facial drooping, arm weakness, speech disturbance, all occurring suddenly, and time. Any sudden neurological deficit, sudden severe headache, or sudden seizure requires urgent neuroimaging and immediate transfer to a centre with neuro care capability. A CT or MRI is mandatory, because you cannot distinguish an ischemic stroke from a haemorrhagic one clinically — the imaging is what tells you whether neurointervention is needed.

There are two distinct subsets. In the acute subset, the stroke is actively evolving and intervention has to happen locally — the thrombolytic drug window is 4.5 hours, and mechanical thrombectomy is 6 hours in all cases, extending to 24 hours in selected imaging-positive cases. Acute stroke care has to be developed in and around the patient's own locality; it can't depend on a distant specialist centre. The second subset is secondary prevention, where the stroke has already happened, the cause has been identified, and we're addressing it to prevent a future event. Those are the patients who can make a calculated decision to travel — most of our overseas patients fall into this category.

It is the point in the neck where the common carotid artery splits into the external carotid artery, which supplies the face, and the internal carotid artery, which supplies the brain.

On direct catheter angiography, stenosis of 50 percent or more is considered significant, while on non-invasive imaging such as CT or MR angiography the threshold is set higher, at 60 percent or more, to account for the lower precision of these methods compared with catheter angiography.

Not usually. Severe stenosis does not typically cause death directly, but the stroke it can precipitate can be catastrophic, so even very tight narrowing close to 99 percent is treated as a serious threat requiring intervention.