The cerebral aneurysms are outpouching of brain arteries, often at a weak spot, and looks like a berry hanging on a stem. A normal arterial wall is made up of three layers. If there is an abnormal loss or absence of the muscular layer of the artery wall, leaving only two layers, an aneurysm can form.
The most common type of cerebral aneurysm is called a saccular, or berry aneurysm, occurring in 90 percent of cases. Other types of aneurysms are fusiform and dissecting aneurysms. Fusiform aneurysms are associated with atherosclerosis (Cholesterol plaque) and dissecting aneurysms are tears along the wall of the artery, causing the blood to flow between the layers of the arterial wall. They can rupture because of trauma or in severe cases, can rupture spontaneously also.
Above: Different Types of Cerebral Aneurysm
The ultimate cause of a brain aneurysm is abnormal degeneration of the arterial wall causing its weakening. The effects of pressure from the pulsations of blood flowing through it enlarge it. However, there are a few identified risk factors for developing an aneurysm:
If you think you are an increased risk, get yourself screened by a trained neurosurgeon for the presence of an aneurysm because timely treatment before it ruptures is lifesaving.
Aneurysms can sit silently for a very long time in the brain and grow larger and larger with time before finally giving away and causing a catastrophic hemorrhagic stroke. Therefore, it is imminent to diagnose an aneurysm before it has ruptured to prevent any future disability or loss of life.
If diagnosed early and treated, aneurysms are harmless and pose no threat to the individual or life. Unfortunately, in the majority of the cases, an aneurysm is diagnosed when it has already ruptured or the weak spot gives away leading to a brain hemorrhage (a hemorrhagic stroke), technically called a “Subarachnoid Hemorrhage”.
The good news is that smaller aneurysms (less than 7mm) have a lower risk of rupture than the larger ones and thus if detected early, while they are still small, they can be effectively treated before they burst.
Aneurysms may cause symptoms by compression of brain structures which are usually caused by either an aneurysm close to nerves or by a large aneurysm technically known as a “Giant aneurysm”. Thus, they affect the function of that region of the brain.
The most common symptom is the closure of one eyelid. The other symptoms can be:
If a hemorrhagic stroke has occurred due to aneurysmal rupture, the symptoms depend upon the size and severity of the stroke.
When an aneurysm ruptures, it is one of the most dramatic symptoms in medicine, often described as “very severe headache” or the “worst headache of my life”. Other symptoms of subarachnoid hemorrhage are:
It can also cause unconsciousness or the worst, sudden death.
Above: CT Scan of a Ruptured Cerebral Aneurysm
The complications that can develop after the rupture of an aneurysm include:
While smaller aneurysms have lesser chances of rupture, there are various factors which predispose an aneurysm for rupture:
With the help of advanced imaging techniques used for brain scannings like CT scans, MRI, and digital subtraction angiography (done in a Cath lab), we can efficiently diagnose even small aneurysms in the cerebral arteries. Hence, timely diagnosis and treatment are possible in all cases if the patient presents to us in the early course of the disease.
Above: A catheter being guided through a small cut in the groin to an artery and then to the blood vessel in the brain where aneurysm is located.
There are several investigations, ideally, a CT scan done within the first 6 hours helps in making a diagnosis of a Subarachnoid hemorrhage. Further presence, morphology, and size of the aneurysm are confirmed by Digital subtraction angiography (DSA).
Above: Ruptured Intracranial Aneurysm with Subarachnoid Hemorrhage
An unruptured aneurysm can be treated via a minimal access route (by making a small hole in the skull) or it can be treated by endovascular route, as preferred nowadays, in a modern neurovascular Cath lab by an endovascular surgeon.
In Minimal access surgery, the blood flow into the aneurysm is stopped by clipping the blood vessel feeding into it. This is known as aneurysmal clipping.
During the endovascular procedure (aneurysmal coiling or flow diversion), the surgeon enters the bloodstream via the artery (usually of the groin) using a catheter and miniature devices like catheters, coils, flow diverters, flow disruptors, and many other similar devices are used to wall off the blood flow into the outpouching or to obliterate the aneurysm itself.
If an aneurysm has already been ruptured, it is a surgical emergency and needs to be managed like a stroke.
A surgery by either of the routes is curative for the existing aneurysms and thus, preventing their risk of future rupture. But, it does not prevent the formation of a new aneurysm elsewhere in the brain in the future. Therefore, a regular follow up is necessary to see if any new aneurysms are growing.
Above: CT Scan of Coil Embolizations (minimally invasive procedure) to treat an aneurysm
Unfortunately, intervention either interventional or microsurgical is the only treatment modality for an aneurysm.
Dr. Vikas being a hybrid neurosurgeon has been treating aneurysms by the endovascular route as well as microsurgical route since the last 20 years. He has continued to upgrade his skills by doing fellowships at the reputed University of Zurich and University of Milwaukee.
Dr. Vikas has also been running a teaching fellowship in Neurovascular interventions for the past 5 years now.