Original popular science article: Intracranial aneurysm

Editor: Kang Yan Reviewer: Yang Pengbin

(Liu Qichen) Today, I will introduce you to a brain disease - intracranial aneurysm. Maybe some people find this word unfamiliar? You connect former British Prime Minister Churchill, former Soviet leader Stalin, former Israeli Prime Minister Sharon, current US President Biden, and China's famous "sketch king" Zhao Benshan, and find their common points? Are you immediately a little "confused"? In fact, these celebrities have all suffered from a disease - intracranial aneurysms (IA). The first three celebrities even died of this disease. Today, we will let a doctor of medicine popularize this disease.

Brain diseases you should know about - intracranial aneurysm

[Science Popularization Assistant] Today, I will introduce you to a brain disease - intracranial aneurysm. Maybe some people find this word unfamiliar? You connect former British Prime Minister Churchill, former Soviet leader Stalin, former Israeli Prime Minister Sharon, current US President Biden, and China's famous "sketch king" Zhao Benshan, and find their common points? Are you immediately a little "confused"? In fact, these celebrities have all suffered from a disease - intracranial aneurysms (IA). The first three celebrities even died of this disease. Today, we will let a doctor of medicine popularize this disease.

[Doctor]: Intracranial aneurysm is a common disease in clinical practice. In fact, it is not a tumor, but a cerebrovascular disease. Intracranial aneurysm is a bulge or bulge formed in some weak parts of the cerebral artery wall due to the long-term impact of blood flow. It is named because of its general shape like a balloon and its resemblance to a "tumor". It often occurs in the larger blood vessels in the brain, such as the cerebral artery circle, the intracranial segment of the internal carotid artery, the middle cerebral artery, the basilar artery, etc.

In most cases, intracranial aneurysms lurk in the body, do not rupture, and are asymptomatic; but once they rupture, it means that the "bomb" explodes, causing a catastrophic blow to the human body, and may lead to serious consequences such as hemiplegia, aphasia, coma, and even death. One-third of patients die within 30 days, and one-third of patients survive, but with neurological loss (disability). In China, the annual incidence of subarachnoid hemorrhage (SAH) caused by intracranial aneurysms is close to 2/100,000, and in some countries it is as high as 22.5/100,000.

How much do you know about the symptoms of intracranial aneurysm?

[Science Assistant]: This disease is so terrible, how can we be sure that we have intracranial aneurysm? What are the symptoms?

【Doctor】: The symptoms of ruptured intracranial aneurysm are obvious and easy to identify. The main manifestations are headache, nausea and vomiting, neck stiffness or pain, and impaired consciousness.

[Science Assistant]: Everyone has headaches. Headaches can occur when you don't sleep well, when you catch a cold, when you have a cold, etc. What kind of headaches indicate a ruptured intracranial aneurysm?

[Doctor]: This is a very good question. Let me explain the above phenomena one by one.

First, the headache of a ruptured intracranial aneurysm is a sudden, severe headache that occurs quickly after the aneurysm ruptures. The pain is often unbearable for patients and is often described as "severe headache", "lightning headache", "explosive headache", "the most severe headache in my life" and "thunderbolt-like pain". US President Biden was hospitalized due to a ruptured intracranial aneurysm. He described this headache as follows: "There were flashes of lightning in my mind, and I felt a strong electric shock. This was the most painful pain I had ever experienced in my life." The characteristics of this headache are: (1) The headache often occurs suddenly, like lightning, and the pain peaks within 1 minute; (2) It is more diffuse and the localization characteristics are not obvious; (3) The headache is severe. This kind of headache is also rare. But once it occurs, it should be taken seriously rather than ignored. Because this kind of headache often indicates the presence of subarachnoid hemorrhage, and the cause behind it is likely to be a ruptured intracranial aneurysm.

The second is nausea and vomiting. When an aneurysm ruptures, blood enters the subarachnoid space, causing vasospasm and insufficient blood supply to the brain tissue, leading to intracranial hypertension, manifested as nausea and vomiting, which are jet-like. Nausea and vomiting often indicate intracranial hypertension.

The third is stiffness or pain in the neck. The subarachnoid space contains cerebrospinal fluid, which is connected to the sulci and cisterns of the entire brain. The direct consequence of aneurysm rupture and bleeding is that blood enters the subarachnoid space. Blood cell metabolites produce inflammatory stimulation to the meninges, and the direct manifestation of stimulation of the occipital meninges is stiffness or pain in the neck.

Fourth, impaired consciousness. It manifests as blurred consciousness or even drowsiness and coma. The main reason is the stress response caused by the sudden bleeding. The second is the extensive subarachnoid hemorrhage causing cerebral vasospasm --- cerebral ischemia. In addition, bleeding can directly lead to intracerebral hematoma and intracranial hypertension. In severe cases, it leads to impaired consciousness. Zhao Benshan showed impaired consciousness when his intracranial aneurysm ruptured.

In addition, visual impairment, decreased vision, narrowed visual field, and in severe cases blindness may occur; as well as increased blood pressure, increased body temperature, gastrointestinal bleeding, and cerebrocardiac syndrome.

[Popular Science Assistant]: It is easy to identify a ruptured intracranial aneurysm, but how to judge if it has not ruptured? Is there any way to prevent it from rupturing?

[Doctor]: Most unruptured intracranial aneurysms have no obvious symptoms. Some patients may experience mild dizziness and corresponding symptoms. When these symptoms occur, the presence of an intracranial aneurysm should be considered. These symptoms are mostly when the aneurysm is large or happens to compress the surrounding nerve tissue.

1. Headache or periorbital pain. This type of headache usually has no localization effect, but periorbital pain is related to the compression of local tissues around the orbit by aneurysms.

2. Visual impairment. Large intracranial aneurysms of the internal carotid artery can directly compress the optic nerve, resulting in visual impairment, or enlarged pupil on one side, or deviation of the eyeball.

3. Eyelid ptosis. Paralysis of the oculomotor nerve on one side will cause the upper eyelid on the same side to ptosis, the eyeball to be in an abducted position, and the inward, upward, and downward movements are restricted. The eyeball movement is impaired, and the pupil is dilated, and the direct and indirect light reflex is impaired. This is related to the oculomotor nerve paralysis, and the space-occupying effect caused by the posterior communicating artery aneurysm is an important cause.

4. Numbness and facial paralysis on one side of the face. Monoplegia or hemiplegia can be caused by the space-occupying effect of the aneurysm or by the detachment of emboli in the aneurysm.

It may also manifest as convulsions, which are mostly caused by middle cerebral artery aneurysms, and may even cause aphasia and mental symptoms. Symptoms such as choking when drinking water, hoarseness, and difficulty swallowing may be caused by compression of the posterior cranial nerves by a posterior inferior cerebellar artery aneurysm or a vertebral basilar artery aneurysm.

The best way is to find the signs and go to the hospital for treatment in time. Use medical means to make accurate judgments, such as digital subtraction angiography (DSA), magnetic resonance angiography (MRA), CT angiography (CTA), etc. When conditions are met and the condition permits, a full-brain DSA examination should be performed as soon as possible to determine the cause of bleeding, decide on the treatment method, and judge the prognosis.

[Popular Science Assistant]: Is there any way to prevent an intracranial aneurysm from rupturing?

[Doctor]: There are usually no obvious symptoms before a cerebral aneurysm ruptures. This is because for some reason the walls of the cerebral arteries become weak, and the arterial walls swell up like a "balloon", sometimes as thin as a piece of paper. As you can imagine, such weak parts are very easy to rupture when subjected to external force or increased blood vessel pressure. Therefore, any factor that causes high blood pressure may cause the rupture of an intracranial aneurysm.

Avoid drastic fluctuations in blood pressure. Any factors that cause a sudden increase in blood pressure can induce aneurysm rupture. For example, under the inducements of mental stress, emotional excitement, fatigue, violent head shaking, sudden bending, rapid standing, drinking, straining to defecate, lifting heavy objects, etc., a sudden increase in blood pressure can easily cause aneurysm rupture and bleeding. For high-risk groups, regular examinations must be carried out, including MRA, CTA, and DSA. Avoid inducing factors in daily life to reduce the occurrence of aneurysm rupture.

Do you know what causes intracranial aneurysm?

[Science Assistant]: What causes it? Can it be prevented?

【Doctor】: The pathogenesis of intracranial aneurysms is still unclear. There are several possible causes.

1. Congenital factors: The thickness of intracranial arteries is 2/3 of the thickness of extracranial blood vessels of the same diameter. The bifurcation of branches is most susceptible to blood flow impact. Cracks appear in the middle layer of the cerebral artery wall, and there are residual embryonic blood vessels or abnormalities and defects in the development of congenital arteries, which are susceptible to blood flow impact and form aneurysms.

2. Arteriosclerosis, the elastic layer in the arterial wall is destroyed, which leads to the arterial wall being unable to withstand greater vascular pressure, causing the weak parts of the artery to bulge and form cerebral aneurysms.

3. Trauma, craniocerebral injury, surgery and other external forces can cause damage to the blood vessel walls of the brain and form cerebral aneurysms.

4. Infection: Infection in any part of the body will spread through the blood in the form of small emboli, and then stay in the terminal branches of the cerebral arteries. When a person's skull base is fractured, the infection will also erode the cerebral arteries from the outside to the inside, causing infected aneurysms or fungal aneurysms.

5. Other reasons. Current research generally believes that the biological process of aneurysms is closely related to genetic and environmental factors. Family history of intracranial aneurysms is one of the independent risk factors for predicting aneurysm rupture that is currently known and widely used in clinical practice. In addition, age and gender are closely related to the occurrence of intracranial aneurysms. The proportion of female patients is significantly higher than that of male patients. Smoking more than 20 cigarettes a day can aggravate inflammatory damage to the intracranial vascular wall, making it more likely to cause aneurysms.

How to prevent intracranial aneurysm, a “time bomb”?

[Popular Science Assistant]: How should we prevent the occurrence of cerebral aneurysms in daily life?

[Doctor]: The cause of intracranial aneurysm formation is still unclear, and it is related to many individual factors of the patient, including genes, heredity, external factors, etc. In addition, we know very little about the causes of intracranial aneurysm formation, and there is no definite and effective means to prevent it. But what is clear is that the formation of aneurysm is caused by damage to the blood vessel wall.

For patients with congenital factors such as a family history of cerebral aneurysms, they should develop good eating and living habits from childhood to prevent the occurrence of cerebrovascular diseases. They should promptly cure trauma and infection, maintain a calm state of mind, avoid emotional excitement, and reduce the impact on intracranial pressure to avoid rupture of cerebral aneurysms.

For middle-aged patients over 40 years old, especially female patients, they must pay attention to a balanced diet and reduce the intake of high-fat, high-cholesterol foods. At the same time, they must control smoking and drinking to reduce the occurrence of diseases such as hypertension and arteriosclerosis, and avoid affecting the elasticity of the cerebral blood vessel walls and inducing cerebral aneurysms.

This is what we can do for aneurysms at present. To be precise, there is no complete prevention method for aneurysms. What we can do is early detection and early treatment, and that's all.

How to defuse a bomb and avoid danger

[Popular Science Assistant]: Is there any good treatment for intracranial aneurysm?

[Doctor]: The treatment of aneurysms is still a high-risk surgery. Whether to undergo surgery should be considered comprehensively. For asymptomatic aneurysms with a diameter of <5 mm and regular shape, dynamic follow-up observation and regular brain CT, MRI and other examinations can be performed.

For ruptured aneurysms with a diameter ≥5 mm and irregular shape, the expected risks and difficulty of surgical treatment are not high; for those with a diameter <5 mm, a comprehensive judgment should be made based on the morphology, location, number and patient condition.

There are two treatments for aneurysms: one is craniotomy to clip the aneurysm. The other is interventional embolization of the aneurysm. Both have their advantages and disadvantages. You should consult a professional doctor about which treatment to choose. Intracranial aneurysm is a cerebrovascular disease, which is completely different from a tumor. Although it is very dangerous, after treatment, it does not require radiotherapy or chemotherapy like a tumor. In any case, cerebral aneurysm is also a benign disease. If diagnosed early and treated in time, the patient can be cured for life after surgery, so there is no need to worry too much.

[Popular Science Assistant]: With the advancement of modern medical technology, whether it is a ruptured or unruptured aneurysm, successful surgical treatment can be achieved, early detection and early treatment can be carried out, and the harm of cerebral hemorrhage to humans can be reduced, turning this "time bomb" into a dud.