What Happens During Brain Aneurysm Coiling — Step by Step

The idea of treating a brain aneurysm through a groin artery sounds remarkable. Here is a detailed explanation of exactly what happens during an endovascular coiling procedure.

Before the Procedure

The patient undergoes MRI/MRA or CT angiography to precisely map the aneurysm's location, size, and neck width. Blood tests, medication review (aspirin and clopidogrel may be started for unruptured aneurysms), and a thorough anaesthesia assessment are completed. The procedure is performed in a specialised biplane angiography suite — a room with high-definition X-ray equipment designed for neurovascular work.

Step by Step

1. Anaesthesia: General anaesthesia is used — not because the procedure is painful (it is not), but to ensure the patient remains completely still throughout the delicate microcatheter navigation within the brain's blood vessels.
2. Groin access: A needle puncture in the right femoral artery (groin) provides access. A thin introducer sheath is placed.
3. Guide catheter placement: A 5–6 French guide catheter is navigated from the groin, up through the aorta, into the carotid or vertebral artery supplying the affected part of the brain.
4. Microcatheter navigation: A 0.017-inch microcatheter is carefully steered through the cerebral arteries — vessels as small as 1–2mm — under live X-ray guidance, until its tip is positioned inside the aneurysm sac.
5. Coil deployment: Tiny platinum coils (0.010 inches in diameter) are fed through the microcatheter into the aneurysm. Each coil is assessed for position and stability before being permanently detached. Multiple coils are packed into the sac until it is fully occluded.
6. Final angiogram: Contrast injection confirms complete exclusion of the aneurysm from the blood circulation. The parent arteries are confirmed to be unaffected.
7. Closure: The groin access is sealed. The patient is woken from anaesthesia and assessed neurologically in the recovery room.

Duration

Simple aneurysms: 1–2 hours. Complex wide-neck aneurysms or WEB procedures: 2–4 hours. The patient typically stays in the intensive care unit overnight for monitoring after a ruptured aneurysm, or in a regular ward room after an elective (unruptured) procedure.