What Is an Aneurysm, and Who Is More Prone to It?
Aneurysms typically develop in the circle of Willis at the base of the brain, at points where vessels branch; they most often favour the anterior communicating artery, the posterior communicating artery and the middle cerebral artery. Size directly affects rupture risk: while the annual rupture probability is quite low in small sacs under 7 mm, this probability climbs as the diameter grows. The two main modifiable risks to emphasise are smoking and uncontrolled blood pressure; to these are added older age, female sex and excessive alcohol. Hereditary and structural causes include a family history of aneurysm, polycystic kidney disease (ADPKD), Ehlers-Danlos Type IV and Marfan syndrome. For this reason, screening with MRA is considered in people who have two or more aneurysms/haemorrhages among first-degree relatives and in certain genetic diseases.
Symptoms and the Haemorrhage (SAH) Emergency
A significant proportion of unruptured aneurysms cause no symptoms and are caught incidentally on an MRI or CT performed for another reason. Larger ones can press on neighbouring structures and cause a drooping eyelid, double vision or loss of vision. When an aneurysm ruptures, subarachnoid haemorrhage (SAH) develops — a true life-threatening emergency: a sudden pain that bursts within seconds, described by patients as “the worst headache of my life”, may be accompanied by neck stiffness, nausea-vomiting, sensitivity to light and loss of consciousness. In such a picture one must go to the emergency department without losing time and call the emergency number. After bleeding, re-bleeding and acute hydrocephalus in the early period, and the vasospasm peaking on days 7–10 later on, are the prominent dangers and are closely monitored in intensive care.
Should We Monitor or Treat?
Surgery is not always required for an unruptured aneurysm; the decision is patient-specific and risk is calculated with tools such as the PHASES score. For small sacs in the anterior circulation, annual imaging follow-up with MRA/CTA and control of risk factors (quitting smoking, balancing blood pressure) is often sufficient. Treatment comes to the fore in the following situations: aneurysms above a certain diameter, those growing rapidly, symptomatic sacs causing pressure signs, smaller sizes with a family history, and young patients with a long expected lifespan. In other words, the sentence “I have an aneurysm” does not by itself mean “I must be operated on”.
Coiling — From Inside the Vessel, Without an Incision
In coil embolisation, the aneurysm is reached with a thin catheter advanced from the groin, and platinum spiral coils are placed inside the sac to isolate the aneurysm from the blood flow. In wide-necked sacs, balloon- or stent-assisted techniques come into play, and in some large aneurysms, flow-diverter stents are used. The procedure is performed under general anaesthesia, does not require opening the skull, recovery is relatively fast (usually a 2–3 day stay), and it is preferred especially in older patients or those at high surgical risk. Its most important weakness is that in some cases the aneurysm can reopen over time (recanalisation), and it usually requires dual antiplatelet medication for a period along with intermittent control angiography.
Microsurgical Clipping — The Open Method
In clipping, the skull is opened and a small titanium clip is placed at the neck of the aneurysm under the microscope, permanently separating the sac from the circulation. During the procedure, whether the clip is correctly seated is checked with ICG angiography, micro-Doppler and neurophysiological monitoring. Offering a permanent solution and a very low chance of reopening are its greatest strengths; it comes to the fore especially in wide-necked complex aneurysms, those located on the middle cerebral artery, and sacs that reopen after coiling. By contrast, it requires opening the skull and its recovery is somewhat longer than coiling (usually a 5–7 day stay). Which method is chosen is decided by weighing together the aneurysm’s diameter, neck width, location and the patient’s overall condition.