Brain aneurysm treatment ranges from careful monitoring to emergency surgery, depending on whether the aneurysm has ruptured and how likely it is to rupture in the future. For unruptured aneurysms, doctors weigh the size, location, and shape of the bulge against the risks of intervention. For ruptured aneurysms, treatment is an emergency that begins in the ICU and moves quickly toward surgery.
How Doctors Decide Whether to Treat
Not every brain aneurysm needs surgical repair. Many small, unruptured aneurysms are monitored with periodic imaging rather than treated right away. Doctors use a scoring system called the PHASES score to estimate the five-year risk of rupture. The score accounts for six factors: the patient’s geographic population, whether they have high blood pressure, their age (with higher risk over 70), the aneurysm’s size, whether they’ve had a previous brain bleed from a different aneurysm, and the aneurysm’s location in the brain.
Size carries the most weight. An aneurysm smaller than 7 millimeters adds zero points, while one 20 millimeters or larger adds 10. Location matters too: aneurysms along certain arteries toward the back of the brain score higher than those along the internal carotid artery. Patients who score below 3 are generally observed. Those above 4 are more likely to be recommended for intervention. Scores of 3 or 4 fall in a gray zone where the decision comes down to individual circumstances, including age and overall health.
Surgical Clipping
Clipping is the traditional open surgical approach. A neurosurgeon makes a small opening in the skull and places a tiny titanium clip across the neck of the aneurysm, sealing it off from normal blood flow. The clip stays in place permanently.
This method is highly durable. Over an average follow-up of about nine years, only 2.9% of clipped aneurysms showed any regrowth. For aneurysms that were completely clipped, the annual regrowth rate was just 0.26%. Interestingly, patients were more likely to develop an entirely new aneurysm elsewhere (0.89% per year) than to see a clipped one come back.
The tradeoff is that clipping is more invasive. Recovery takes at least four to six weeks, and complication rates are higher than with less invasive alternatives. In a large study of elective (non-emergency) procedures, clipping carried a hospital mortality rate of 1.6% and a post-procedure stroke rate of 6.7%. The overall rate of any serious complication was about 8.4%.
Endovascular Coiling
Coiling is a less invasive option. Instead of opening the skull, a doctor threads a thin catheter through an artery, usually starting in the groin, and guides it up to the aneurysm. Tiny platinum coils are packed inside the aneurysm, causing blood to clot around them and effectively shutting the aneurysm off from circulation.
Coiling has significantly lower complication rates than clipping for elective procedures. Hospital mortality drops to about 0.6%, post-procedure stroke occurs in roughly 3% of cases, and the overall serious complication rate is about 3.7%. Recovery is also faster since no part of the skull is opened.
The main limitation is durability. Coiled aneurysms are more likely to reopen over time than clipped ones, which means you’ll need follow-up imaging (typically with MRI) at regular intervals to check that the coils are still holding. Some patients eventually need a second procedure.
Flow Diverters for Complex Aneurysms
Flow diverters are a newer endovascular option, originally developed for giant or wide-necked aneurysms that are difficult to coil. These are mesh stents placed inside the parent artery, redirecting blood flow away from the aneurysm. Over weeks to months, the aneurysm gradually clots off and shrinks.
Their use has expanded beyond giant aneurysms to include small and medium-sized ones, and even aneurysms on smaller vessels. In a large international study comparing several flow diverter designs, the overall complete closure rate was 72% at last follow-up. Different devices had slightly different strengths: some navigated twisting blood vessels better, while others worked better in larger arteries or in patients with unusually shaped vessels. The choice of device typically depends on the specific anatomy of your aneurysm and the surrounding arteries.
When an Aneurysm Ruptures
A ruptured aneurysm causes bleeding around the brain, known as a subarachnoid hemorrhage. This is a life-threatening emergency. Treatment begins immediately in the ICU, where the priority is stabilizing blood pressure, managing pain, and preventing seizures. The goal is to seal the aneurysm as quickly as possible, using either clipping or coiling, to stop the bleeding and prevent a second rupture.
Even after the aneurysm is secured, a dangerous complication called vasospasm can develop between days 3 and 21. This is when blood vessels near the bleed tighten and restrict blood flow to the brain, potentially causing stroke-like symptoms: worsening headache, confusion, or new neurological problems. The medical team monitors closely during this window and keeps blood pressure at levels that maintain adequate blood flow to the brain.
What Recovery Looks Like
Recovery timelines differ substantially between the two main approaches. After open clipping, most people need at least four weeks off work, and many need longer depending on the physical demands of their job. For the first three months, you’ll be advised to avoid strenuous exercise, heavy lifting, contact sports, and risky activities like climbing ladders. Even everyday tasks may tire you out more quickly than expected during the first several weeks.
Endovascular procedures (coiling or flow diverters) generally allow a faster return to daily life since the skull isn’t opened, though you’ll still have activity restrictions and need time to recover from the procedure itself.
Regardless of the method used, long-term follow-up is part of the treatment plan. Coiled aneurysms need periodic imaging to check for reopening. Clipped aneurysms are more stable but still warrant occasional monitoring, partly because the rate of forming a completely new aneurysm elsewhere in the brain is higher than the rate of a clipped one regrowing. Your treatment team will set an imaging schedule based on the type of repair and your individual risk factors.