Aneurysms

Cerebral (brain) aneurysms are sacs (dilatations) of the brain vessels (arteries) mostly at the branching points (bifurcation, trifurcation). They are also knows as berry aneurysms since they resemble berries- having a neck and a dome. These dangerous blood vessel sacs may tear (burst) and cause deadly bleedings inside the brain with potentially catastrophic consequences which include coma, vegetative status, and death.

Brain aneurysms are serious and potentially life threatining lesions which require medical care once they are diagnosed. While up to 3-5% of people (prevalence rate) may carry these deadly sacs, rupture (burst) rate is quite low (5-10/100.000). Smoking and cocaine use appeared to be directly related to the the formation of aneurysms and hypertension and atherosclerosis facilliate aneurysms to grow further.

Aneurysms may grow silently for years and reach to enormous sizes over 25 mm in diameter and these aneurysms are called giant aneuryms which may cause pressure onto the surrounding nerves and brain thus patients may admit to hospital with the complaints of eyelid-drop (ptosis), headache, muscle weakness in one side of the body, blurred vision, and in difficulty moving eyeballs. On the other hand, some aneurysms cause thinning of the vessel wall without an obvious dilatation and these aneuysms may also cause fatal bleedings.

Brain aneurysms maybe saccular (sac in shape), fusiform, and dissecting, saccular type is being the most common morphology.

The diagnostic imaging modalities of the brain aneurysms are computed tomography angiography (CTA), magnetic resonance imaging angiography (MRA), and digital substraction angiograpy (DSA). The former 2 techniques CTA and MRA are non-invasive techniques while DSA requires a vessel puncture and catheterization. In burts aneurysms, computed tomography is the best and the fastest tool to diagnose the blood spilliage in the subarachoid space and any associated blood clot in the brain.

Most cerebral aneurysms (85-90%) are located in the so called ‘anterior circulation territory’ while 10-15 % are located in the so called ‘posterior circulation-aka. vertebrobasilar system.

The most common sites of aneurysms in anterior circulation are anterior communicating artery (Acom), posterior communicating artery (Pcom), and middle cerebral artery aneurysms (MCA).

Basilar apex (tip) aneurysms are the most common aneurysms in the posterior circulation.

Once aneurysms burst, they cause ‘subarachnoid hemorrhage’ (bleeding in between the brain inner membranes) and may cause expanding blood clot inside the brain parenchyma. Thus, urgent securing of the aneurym and evacuation of any associated blood clot is of extreme importance to prevent re-bleeding and relaxation of the brain.

Securing of aneurym neck by a placement of a metal clip (aneurysm clipping) is the main strategy in micro-neurosurgical treatment of brain aneurysms and only the experienced and well trained neurosurgeons may execute this demanding job properly.

Secondary treatment options of aneurysms include endovascular therapy and bypass surgeries.

Intensive care (ICU) follow up after aneurysm clipping surgery is very crucial since significant portion of patients with burst aneurysms develop vasospams (narrowing of major brain arteries due to blood) at varying degrees and hydrocephalus (accumulation brain-spine fluid in the brain cavities).