A cerebral aneurysm is also referred to as a cerebral vasodilatation, arterial dilatation in the brain or an arterial bulge in the brain. It is a spindle-shaped, berry-shaped or sac-shaped dilation of arterial brain vessels.
The cerebral vasodilatation has a diameter of about 5 mm to 3 cm. If the cerebral vascular dilatation is 2.5 cm or more in size, it is a giant aneurysm.
An aneurysm in the brain occurs particularly in the vessels at the base of the brain. Due to the structure of the vessel wall, the branching points of the arteries are usually affected.
Illustration of a brain aneurysm © freshidea | AdobeStock
A serious complication of a brain aneurysm is an aneurysm rupture, i.e. the aneurysm bursts or tears.
As a ruptured brain aneurysm can quickly become life-threatening, immediate treatment is required. A brain aneurysm can rupture at any age. However, the risk of rupture of a cerebral vascular dilatation is highest in the fifth and sixth decade of life.
15 to 20% of aneurysm patients have more than one cerebral vasodilatation. In about 10 to 20% of cases, there are multiple aneurysms in the arteries at the base of the brain. It is estimated that between 0.2 and 9% of Central Europeans have aneurysms. This means that around 2,000 to 90,000 per 1 million people have a brain aneurysm. Women are more frequently affected than men.
A brain aneurysm is caused by changes in the endothelial cells of the inner wall of the blood vessel.
It is often not possible to clearly determine the cause of a cerebral vasodilatation. Brain aneurysms occur more frequently in some families. It is therefore assumed that not only acquired but also congenital factors lead to the vascular changes.
Over the years and in the presence of other factors, e.g.
a brain aneurysm can develop.
The muscle layer around the cerebral arteries at the base of the brain is thinner than that of the other arteries in the body. Therefore, the cerebral arteries at the base of the brain are particularly susceptible to a brain aneurysm.
High blood pressure (hypertension) is an important risk factor for cerebral vasodilatation. The blood exerts high pressure on the inside of the vessel walls. If the vessel wall is weakened at a certain point, this area can give way and the weak point is pushed outwards like a sac. This is how a brain aneurysm develops.
Arteriosclerosis(vascular calcification) is another risk factor for a brain aneurysm. The calcium deposits cause the cerebral arteries to lose their elasticity, making the vessels less able to cushion the pressure waves of the heartbeat.
High blood pressure is a risk factor for the formation of a brain aneurysm © wutzkoh | AdobeStock
Other risk factors for a brain aneurysm are
- Smoking,
- an advanced age,
- heavy alcohol consumption,
- head injuries and
- some hereditary diseases (e.g. Marfan syndrome, Ehlers-Danlos syndrome).
A brain aneurysm often causes no symptoms at the beginning.
However, if the cerebral vasodilatation presses on a cranial nerve, symptoms may occur. Unlike peripheral nerves, cranial nerves do not originate from the spinal cord, but directly from the brain. This often results in paralysis and facial paralysis.
If the cerebral vasodilatation bursts, a cerebral hemorrhage or stroke occurs.
Symptoms of a non-ruptured brain aneurysm
The facial nerve(oculomotor nerve) is usually affected by the cerebral vasodilatation. The facial nerve is responsible for eye movements. Therefore, pressure on the nerve from the brain aneurysm can lead to, among other things
- Movement disorders of the eyes,
- Eye muscle paralysis,
- Pain above and behind one eye,
- dilated pupils,
- seeing double vision,
- drooping eyelid up to and including
- paralysis of one side of the face
can occur.
Such symptoms can usually be alleviated by brain aneurysm surgery.
Symptoms of a ruptured brain aneurysm
A brain aneurysm at the base of the brain is very dangerous. If a vasodilatation of a large cerebral vessel at the base of the brain bursts, this can lead to bleeding into the subarachnoid space. This is referred to as an aneurysmal subarachnoid haemorrhage (SAH ). The subarachnoid space is the space between the brain and the meninges, which is known asthe arachnoid membrane.
A subarachnoid hemorrhage occurs every year in about 100 people per 1 million inhabitants.
[IMAGE]
As the cerebral hemorrhage cannot drain to the outside due to the bony skull, the pressure on the brain increases. This can lead to serious damage to the brain. Up to 60 to 70% (some sources even report up to 90%) of patients do not survive the cerebral hemorrhage.
Only around 10% of patients with a ruptured brain aneurysm do not suffer any neurological deficits. The remaining patients suffer neurological deficits, e.g.
- loss of speech,
- complete or partial paralysis (paresis) or
- hemiplegia (hemiparesis).
Symptoms that can be attributed to the increased intracranial pressure may include
- Sudden, very severe headaches,
- Nausea and vomiting,
- neck stiffness,
- drowsiness,
- sensitivity to light,
- drowsiness,
- unconsciousness and
- coma
may occur. Immediate brain aneurysm surgery is necessary in the event of a ruptured brain aneurysm.
A brain aneurysm does not necessarily cause symptoms. It is therefore often discovered by chance as an incidental finding during a computer tomography (CT) scan or magnetic resonance imaging (MRI) of the head.
If the cerebral aneurysm has burst, the symptoms (e.g. sudden onset of headaches) can often lead to a suspected diagnosis.
If cerebral vasodilatation is suspected, imaging procedures can help. They can clearly show the ruptured cerebral aneurysm and a cerebral haemorrhage. Other diagnostic tests include a cerebrospinal fluid examination and cerebral angiography.
In most cases, the first diagnostic measure is a computer tomography (CT) scan. If necessary, a contrast agent is used. This X-ray examination provides a good view of the blood flow in the brain. Brain haemorrhages and a burst brain aneurysm can also be easily detected.
Magnetic resonance imaging (MRI ) usually provides more detailed findings of bleeding and cerebral vasodilatation than CT. X-rays are also not used.
In the case of a subarachnoid hemorrhage, the red blood cells can be detected by examining the cerebrospinal fluid (CSF). The cerebrospinal fluid examination is usually performed if a CT scan does not indicate a hemorrhage, but the symptoms do. This involves taking a small amount of cerebrospinal fluid from the spinal canal with a needle as part of a lumbar puncture.
If these examinations do not provide any definitive findings, a cerebral angiography can be performed. For this, a thin and flexible catheter is inserted into a large artery, usually from the groin into the brain. A dye is used to stain the cerebral arteries. A burst aneurysm can then be clearly visualized on a CT scan.
Screening for a non-ruptured brain aneurysm is particularly recommended if
- a parent or sibling has suffered from a ruptured brain aneurysm or
- if there is a congenital disease that increases the risk of cerebral vasodilatation.
Not every accidentally discovered brain aneurysm poses a risk. If the brain aneurysm does not cause any symptoms and the vessel walls are stable, there is often no need for treatment. Regular check-ups are then sufficient.
However, if there is a risk of an aneurysm rupture, the vessel must be treated preventively. It is reinforced at the weakened site or the brain aneurysm is clamped (clipping). There is a risk, for example, if there is a hereditary predisposition and certain risk factors.
The clip used for clipping is a metal clamp that the surgeon places at the base of the dilated cerebral vessel. The lumen of the vessel is not narrowed in the process.
Alternatively, small platinum coils can be inserted using a minimally invasive, endovascular procedure(coiling).
Other neurosurgical forms of brain aneurysm surgery include
- Wrapping: the weakened vascular sites are wrapped with the patient's own tissue or foreign material for reinforcement
- trapping: small balloons are inserted before and after the brain aneurysm.
Acute secondary bleeding from a ruptured brain aneurysm is the cause of the high mortality rate within the first few days after the rupture. The most important goal in all aneurysmal cerebral haemorrhages is therefore to stop the bleeding as quickly as possible and to close the source of the bleeding.
Early surgery (0 to 3 days after the subarachnoid hemorrhage) usually shows better long-term results than late surgery (11 to 14 days after the subarachnoid hemorrhage). The least favorable results are to be expected with surgery between the 7th and 10th day after the subarachnoid hemorrhage.
Even today, patients with severe symptoms or persistent unconsciousness are often only operated on after their condition has stabilized.
Depending on
- age,
- general condition and
- location, size and shape of the cerebral vasodilatation
treatment is generally either endovascular or neurosurgical.
Endovascular brain aneurysm surgery (endovascular coiling, endovascular aneurysm occlusion)
In endovascular brain aneurysm surgery, a hollow microcatheter is advanced from the groin into the defective cerebral artery. The surgeon then inserts a stent. A stent is a fine wire mesh that reinforces the vessel wall from the inside.
Microcoils made of a platinum alloy (coils) are then inserted into the aneurysm sac using a guide wire. Although these microcoils only partially fill the brain aneurysm, they cause a thrombus to form. In this way, they prevent further blood circulation in the brain aneurysm and a possible rupture.
This brain aneurysm operation does not require neurosurgical opening of the skull or surgery on the brain. This minimally invasive brain aneurysm operation is therefore the preferred technique.
If there are no complications, the coil material remains permanently in the brain and does not need to be removed.
Tiny coils partially fill the brain aneurysm (coiling) © Naeblys | AdobeStock
If coiling is not possible or if the brain aneurysm has burst (emergency treatment), a different method is required. A neurosurgeon then opens the skull. Three techniques are now conceivable:
Neurosurgical brain aneurysm operation: clipping
During clipping, the neck of the vascular sac is completely clamped off with a clip (usually made of titanium). This separates the aneurysm sac from the blood circulation. The cerebral vessel on which the brain aneurysm is located remains intact.
If the clip does not fit perfectly, there is a risk that
- the formation of a new brain aneurysm or
- a stenosis (occlusion) of the carrier vessel.
In some cases, a control angiography is therefore performed postoperatively. If there are no complications, the clipping material remains permanently in the brain and does not have to be removed.
The aneurysm is clamped off during clipping © ilusmedical | AdobeStock
Neurosurgical brain aneurysm operation: wrapping
During wrapping, the surgeon wraps the arterial wall of the cerebral vascular dilatation. Wrapping can be carried out with the body's own tissue (e.g. muscle or fascia) or with foreign material (e.g. gauze, linen or plastic). The subsequent connective tissue wall reinforcement is intended to prevent a rupture.
However, the brain aneurysm remains intact during wrapping. It can also increase in size, which is why the protective effect of this brain aneurysm operation is controversial.
Neurosurgical brain aneurysm operation: trapping
The term trapping is used when the surgeon uses a blood vessel above and below the cerebral vasodilatation using
- clips or
- with endovascularly placed balloons
balloons.
This procedure can only be used if the area of the brain dependent on the affected cerebral artery is otherwise supplied. For this reason, extensive cerebral blood flow tests and functional tests are required prior to the brain aneurysm operation.
Follow-up treatment after brain aneurysm surgery
After a neurosurgical or endovascular brain aneurysm operation, the patient must be closely monitored. In this way, any complications can be detected and treated in good time.
Treatment of symptoms and complications
In addition to direct surgical treatment of cerebral vasodilatation, symptoms and complications are usually treated with medication. For example, the patient receives
- Painkillers for headaches and
- calcium channel blockers to prevent vasospasm. Vasospasm is a narrowing of the intracranial cerebral arteries, which can result in severe cerebral infarction with a fatal outcome.
given. The cerebrospinal fluid circulation disorder, which can be detected on CT just a few hours after the hemorrhage, is treated with lumbar drainage or ventricular drainage.
Patients with a non-ruptured cerebral aneurysm can reduce the risk of rupture of the cerebral vascular dilatation. The most important point is a healthy lifestyle:
- Refrain from smoking and drugs.
- Make sure you eat a healthy and balanced diet and get enough exercise. Changing your diet and being physically active can lower your blood pressure.
- Limit your caffeine consumption. Caffeine can lead to a sudden rise in blood pressure.
- Avoid overexertion. Sudden and intense physical exertion (e.g. weight lifting) can lead to a sudden rise in blood pressure.
- Be careful when taking acetylsalicylic acid (aspirin) and other medications that inhibit blood clotting. Discuss this with your doctor, as these drugs increase the risk of bleeding in the event of a brain aneurysm.
