EXPLAINED | What Is Cerebral Aneurysm? The Cerebrovascular Disease Xi Jinping Is Said To Be Suffering From

Cerebral aneurysm, also called a brain aneurysm or intracranial aneurysm, is a ballooning or bulge in a blood vessel of the brain, due to weakness in the wall of the vessel.

Cerebral aneurysm is a cerebrovascular disease arising due to weakening of a blood vessel in the brain (left) (Johns Hopkins); Xi Jinping (right) is reportedly suffering from cerebral aneurysm (AFP)

Source : Johns Hopkins/AFP

New Delhi: The President of China, Xi Jinping, is reportedly suffering from a cerebral aneurysm, a cerebrovascular disease. He had to be hospitalised at the end of 2021, and preferred to be treated with traditional Chinese medicines rather than going for surgery, media reports said.

Since the outbreak of Covid-19 till the 2022 Beijing Winter Olympics, Xi had avoided meeting foreign leaders, giving rise to speculations about his health. 

What Is Cerebral Aneurysm?

Cerebral aneurysm, also called a brain aneurysm or intracranial aneurysm, is a ballooning or bulge in a blood vessel of the brain, due to weakness in the wall of the vessel. In this cerebrovascular disease, the vessel fills with blood. The vessel develops a blister-like dilation that can become thin and rupture without warning.

Cerebrovascular diseases are brain blood vessel blockages, bleeding, or other problems which disrupt the regular flow of blood to the brain, depriving it of necessary oxygen that can subsequently cause damage to the brain. 

The aneurysm will rupture and bleed into the space around the brain, in case the aneurysm expands and the blood vessel wall becomes too thin, according to Baltimore-based Johns Hopkins Medicine. This event is called a subarachnoid haemorrhage (SAH), which may cause a haemorrhagic (bleeding) stroke and is a life-threatening event. The resultant bleeding into the space around the brain can also lead to a coma. A brain aneurysm requires immediate medical treatment. 

Aneurysms are usually found at the base of the brain just inside the skull, in an area called the subarachnoid space, according to the American Association of Neurological Surgeons, headquartered in Illinois, United States. The terms SAHs and aneurysms are often used synonymously because 90 per cent of SAHs are attributed to ruptured cerebral aneurysms. 

An aneurysm ruptures when a hole develops in the sac of the aneurysm, which can range in size from small to nearly one inch. Giant aneurysms are the aneurysms which are larger than one inch are called giant aneurysms, pose a particularly high risk, and are difficult to treat.

The hole of an aneurysm can be small, in which case only a small amount of blood leaks, or large, which leads to a major haemorrhage. An aneurysm whose sac has not previously leaked is called an unruptured aneurysm. 

Symptoms Of Cerebral Aneurysm

The presence of a brain aneurysm may not be known until it ruptures, as most brain aneurysms are devoid of symptoms, and small in size, which have a lower risk of rupture than giant aneurysms. The diameter of a small aneurysm is less than 10 millimetres or less than four-tenths of an inch. 

Sometimes, a small amount of blood may leak, which can result in symptoms that happen before a rupture. This is known as sentinel haemorrhage to the brain. Since some aneurysms press on adjacent structures, such as nerves to the eye, they may be symptomatic. For instance, they may cause visual loss or diminished eye movements, even if the aneurysm has not ruptured. 

The symptoms of an unruptured brain aneurysm include headaches, eye pain, vision changes, and diminished eye movement. 

The first evidence of a brain aneurysm is most often a SAH which occurs due to rupture of the aneurysm, and may cause symptoms such as rapid onset of "worst headache of one's life", stiff neck, nausea and vomiting, changes in mental status, pain in specific areas, dilated pupils, loss of consciousness, high blood pressure, loss of balance or coordination, sensitivity to light, back or leg pain, problems with certain functions of the eyes, nose, tongue, and ears that are controlled by one or more cranial nerves, and coma and death, among others. 

Risk Factors For Cerebral Aneurysm

Inherited risk factors for cerebral aneurysm include alpha-glucosidase deficiency, alpha-1 antitrypsin deficiency, arteriovenous malformation (AVM), coarctation of the aorta, Ehlers-Danlos syndrome, fibromuscular dysplasia, hereditary hemorrhagic telangiectasia, Klinefelter syndrome, Noonan's syndrome, Polycystic kidney disease (PCKD), and tuberous sclerosis, among others. 

Alpha-glucosidase deficiency is a complete or partial deficiency of the enzyme needed to break down glycogen and convert it into glucose, while alpha-1 antitrypsin deficiency is a hereditary disease that may lead to hepatitis and cirrhosis of the liver or emphysema of the lungs. Arteriovenous malformation is an abnormal connection between an artery and a vein. Coarctation of the aorta is a narrowing of the aorta, which is the main artery coming from the heart. 

Ehlers-Danlos syndrome is a connective tissue disorder that is less common. Fibromuscular dysplasia is an arterial disease that most often affects the medium and large arteries of young to middle-aged women. 

Hereditary hemorrhagic telangiectasia is a genetic disorder of the blood vessels in which there is a tendency to form blood vessels that lack capillaries between an artery and vein. 

Klinefelter's syndrome is a genetic condition in men in which an extra X chromosome is present. Noonan's syndrome is a genetic disorder that causes abnormal development of many parts and systems of the body. 

Polycystic kidney disease is a genetic disorder characterised by the growth or numerous cysts filled with fluid in the kidneys, and is the most common medical disease associated with saccular aneurysms. 

Tuberous sclerosis is a type of neurocutaneous syndrome, which is a disorder that can affect the brain, spinal cord, organs, skin, and skeletal bones. 

Acquired risk factors associated with aneurysm formation include advancing age, alcohol consumption, atherosclerosis, which is a buildup of plaque in the inner lining of an artery, cigarette smoking, use of illicit drugs such as cocaine or amphetamine, high blood pressure, head injury, and infection, among others. The risk factors increase a person's risk, but do not necessarily cause cerebral aneurysm.

How Can Brain Aneurysm Be Diagnosed?

According to Johns Hopkins, a brain aneurysm is discovered after it has ruptured or by chance during diagnostic exams, such as computed tomography (CT) scan, magnetic resonance imaging (MRI), or angiography (a type of X-ray used to check blood vessels) that are being done for other reasons. 

The diagnostic procedures for a brain aneurysm may include cerebral angiography, computed tomography scan, magnetic resonance imaging, and magnetic resonance angiography, in addition to a complete medical history and physical exam. 

Cerebral angiography provides an image of the blood vessels in the brain to detect a problem with vessels and blood flow. A CT scan is an imaging test that uses X-rays and a computer to make detailed images of the body, and may be used to detect abnormalities and identify the location of the aneurysm, and check if it has burst or is leaking. An MRI is a diagnostic procedure that uses a combination of large magnets, radio frequencies, and a computer to produce images of organs and structures within the body. It detects small changes in brain tissue using magnetic fields, in order to locate and diagnose an aneurysm. An MRA is a non-invasive procedure that uses a combination of magnetic resonance technology and intravenous contrast dye, which causes blood vessels to appear opaque on the MRI image, allowing the doctor to visualise the blood vessels being evaluated.

How Can Brain Aneurysm Be Treated?

Depending on the size and location of the brain aneurysm, and whether or not it has ruptured, one or more techniques are used to treat the disease. Broadly, there are three treatment options for people with cerebral aneurysm — medical (non-surgical therapy, surgical therapy or clipping, and endovascular therapy or coiling with or without adjunctive devices. 

Other methods include flow diversion with stents, artery occlusion and bypass, and observation. 

Medical Therapy

According to AANS, medical therapy is usually only an option for the treatment of unruptured cerebral aneurysms. Strategies include smoking cessation and blood pressure control, because these are the only factors that have been shown to have a significant effect on aneurysm formation, growth, or rupture.

Surgical Clipping

An aneurysm is clipped through craniotomy, which is a surgical procedure in which the brain and the blood vessels are accessed through an opening in the skull, after the bulge is identified. 

The aneurysm is carefully separated from the surrounding brain tissue, following which a small metal clip, usually made from titanium, is applied to the neck of the aneurysm. 

Endovascular Coiling

Endovascular coiling is a procedure performed to block blood flow into an aneurysm, and is a minimally non-invasive technique, which means that an incision into the skull is not required to treat the aneurysm.

The process involves passing a catheter through the groin up into the artery containing the aneurysm, where platinum coils are released, to induce clotting of the aneurysm, and thus, prevent blood from getting into it. 

Flow Diversion With Stents

Flow diversion is an endovascular technique in which the device is placed in the parent blood vessel to divert blood flow away from the aneurysm itself, instead of placing a device inside the aneurysm sac. A microcatheter is navigated past the aneurysm without having to enter the aneurysm, following which the flow-diverting device is deployed across the neck of the aneurysm in the parent blood vessel where the aneurysm is present. 

Artery Occlusion And Bypass

Artery occlusion and bypass is a two-part procedure combining open microsurgery and endovascular coiling, in order to coil the entire diseased portion of the blood vessel and then bypass the blood flow to the specific location in the brain. Artery occlusion and bypass is different from endovascular coiling in the fact that the former closes down the whole vessel rather than just putting coils in the aneurysm sac. 

Flow Disruption

Intramuscular flow disruption with a WEB (Woven EndoBridge) device is one of the latest technological advancements in the management of wide-necked aneurysms, especially at the bifurcation of an artery. The WEB device, which is an innovative endovascular device used for the treatment of intracranial aneurysms, is placed within an aneurysm in contrast to the flow diversion stents which are placed in the parent artery.