Coiling vs clipping: which aneurysm treatment is better?

Neither coiling nor clipping is better for every brain aneurysm. Coiling is a less invasive procedure done from inside the blood vessels and usually has a faster recovery, while clipping is open surgery that tends to be more durable and less likely to need a second treatment. The best choice depends on the aneurysm's size, shape and location, the patient's age and health, and the experience of the treating team.

What is the difference between coiling and clipping?

Clipping closes the aneurysm from the outside, while coiling fills it from the inside. Both aim to stop blood from entering the weak, ballooned section of the artery so it cannot bleed, or bleed again.

• Surgical clipping. A neurosurgeon performs a craniotomy, which means temporarily removing a small window of skull, then works between the folds of the brain to reach the aneurysm. A small metal clip is placed across the aneurysm's neck (where it joins the normal artery), sealing it off. The bone is put back at the end of the operation.
• Endovascular coiling. A thin tube called a catheter is passed into an artery, usually in the groin or wrist, and guided up into the brain using live X-ray imaging. Soft platinum coils are fed into the aneurysm, where they fill the space and encourage the blood inside to clot, cutting the aneurysm off from circulation.

Which is better, coiling or clipping?

Each approach has trade-offs, and specialists weigh them case by case. The table below shows the general pattern, though individual cases vary.

	Clipping	Coiling
How it is done	Open surgery through the skull	Catheter through the blood vessels
Hospital stay (unruptured)	Usually several days	Often 1 or 2 nights
Recovery	Usually several weeks	Often about a week
Durability	Very durable once fully clipped	Some aneurysms refill over time
Follow-up imaging	Often limited	Usually repeated scans over years

Several features of the aneurysm and the patient tend to shape the decision:

• Location. Aneurysms deep at the back of the brain, such as at the tip of the basilar artery, are hard to reach surgically, so coiling is often favored. Middle cerebral artery aneurysms often have branches arising near the neck and are frequently clipped.
• Shape. A wide-neck aneurysm has a broad opening that makes it harder for coils to stay in place. These may need extra devices or surgery.
• Bleeding into the brain. If a rupture has caused a large blood clot that needs to be removed, open surgery can remove the clot and clip the aneurysm at the same time.
• Age and health. Older patients and people with serious medical conditions often tolerate a less invasive procedure better.
• Team expertise. Results depend on the skill and experience of the people doing the procedure, so local expertise matters.

Coiling vs clipping in ruptured aneurysms: what did ISAT find?

The International Subarachnoid Aneurysm Trial (ISAT) is the best-known head-to-head comparison, and it found better one-year outcomes with coiling but more need for retreatment. The trial enrolled people with ruptured aneurysms that doctors judged suitable for either treatment and randomly assigned them to coiling or clipping.

At one year, fewer patients in the coiling group had died or become dependent on others for daily care (roughly 24 percent versus 31 percent in the clipping group). The trade-off was durability: coiled aneurysms were more likely to need a second procedure, and the risk of a later rebleed, while low after both treatments, was somewhat higher after coiling. Long-term follow-up continued to favor coiling for survival and independence.

ISAT has important limits. Most participants had small aneurysms in the front part of the brain's circulation and were in fairly good condition after their bleed, so the results do not automatically apply to every aneurysm. Devices and techniques have also changed since the trial. Since then, coiling has become the first option for many ruptured aneurysms in many centers, while clipping remains the better fit for others.

Is aneurysm coiling considered brain surgery?

Coiling is a brain procedure, but it is not open brain surgery. The skull is not opened and there is no scalp incision; the only opening is a small puncture in an artery at the groin or wrist. It is usually done under general anesthesia by a neurointerventional specialist, who may be a neurosurgeon, a neuroradiologist or a neurologist with specialized training.

Because it is less invasive, recovery is usually quicker than after clipping. It still carries real risks, including stroke from a small clot and bleeding from the aneurysm during the procedure, so hospitals treat it with the same seriousness as an operation.

What is aneurysm coiling with stenting?

Stent-assisted coiling places a small mesh tube in the main artery across the aneurysm's neck, which acts like a scaffold to hold the coils inside. It is mostly used for wide-neck aneurysms that would not hold coils on their own.

A stent requires antiplatelet medicines, often two at first, to keep clots from forming on it. These medicines raise bleeding concerns right after a rupture, so many teams avoid stents in that setting when another option works. Other tools for difficult shapes include balloon-assisted coiling, flow diverters (dense stents that redirect blood so the aneurysm gradually closes) and devices placed inside the aneurysm itself, such as the Woven EndoBridge (WEB) device.

Why do coiled aneurysms need follow-up?

Coiled aneurysms need follow-up because some of them refill over time. Coils can compact and blood can push back into part of the aneurysm, a process called recanalization. Most patients have repeat imaging over the following months and years, and only a portion of recurrences are large enough to need retreatment.

The risk is not the same for everyone. Larger aneurysms, wide necks, ruptured aneurysms and aneurysms that were not fully closed at first all tend to carry higher recurrence risk. Researchers are building models that estimate an individual aneurysm's recurrence risk after coiling, such as this recanalization risk calculator.

Frequently asked questions

Is coiling safer than clipping?

For many patients, coiling carries lower immediate risk and allows a faster recovery, which is the main reason ISAT favored it at one year. But safety depends on the aneurysm. For some shapes and locations, clipping is the safer and more durable choice overall.

Can a clipped aneurysm come back?

A completely clipped aneurysm very rarely comes back, which is why clipping is considered durable. Aneurysms that were only partly clipped can regrow, and some people develop new aneurysms elsewhere, so doctors may still recommend occasional imaging.

How long does recovery take after each procedure?

After coiling of an unruptured aneurysm, many people return to normal activities within about a week. After clipping, recovery usually takes several weeks. After a rupture, recovery depends mainly on the bleed itself rather than the treatment, and it can take months.

Can a coiled aneurysm be treated again?

Yes. An aneurysm that refills after coiling can often be treated again with more coils, a stent or a flow diverter, and occasionally with surgical clipping. The choice depends on the size and shape of the recurrence.

Who decides between coiling and clipping?

Ideally, the decision is made by a team that includes both open vascular neurosurgeons and endovascular specialists, together with the patient and family. Asking whether both options were considered, and why one was recommended, is a reasonable question for any patient.