What is Aneurysm?
What is Brain Aneurysm?
An aneurysm is dilation and ballooning of a weak spot of an artery.What is the incidence of aneurysm?
It is a disease that has developed or may develop at a rate of 1.5-5% of the general population. According to this calculation, 1 million 200 thousand - 4 million people in Turkey have or will have aneurysm. Most of these aneurysm patients do not have any complaint. 1-3% of patients with brain vessel aneurysm may develop brain hemorrhage. Unfortunately, about half of patients with aneurysm-induced cerebral hemorrhage pass away.How does aneurysm occur?
Aneurysms are usually not congenital. They usually occur after 40 years of age. It may also occur as from the age of 20’s. People with more than two first-degree relatives who had an aneurysm are 5 times more likely to have an aneurysm than normal individuals.Aneurysms usually occur at the bifurcation sites of the vessels and are thought to develop due to exposure of these regions to continuous pressure. They grow slowly and as they grow, their walls become weaker. They are more common in some vascular diseases (fibromuscular dysplasia, cerebral arthritis, arterial dissection). Infection, use of medicines (amphetamine) or drug use such as cocaine have a role in the development of some aneurysms.
Are all aneurysms the same?
No. Aneurysms vary by size, shape and location.
By size:
- Small aneurysms: Smaller than 5 mm
- Moderate aneurysm: Measuring 6-15 mm in size
- Large aneurysms: Measuring 16-25 mm in size
- Giant: Greater than 25 mm
By shape:
- Saccular: In the form of a balloon with a narrow neck according to its size
- Wide neck: In the form of a balloon with a wide neck according to its size
- Fusifom: In the form that a segment of a vessel expands in all its walls
By location:
Aneurysms usually occur in the main arteries in the immediate vicinity of the brain tissue. If it originates from a side wall of a flat vessel, it is called "sidewall aneurysm" and if it's located in bifurcation region of a vessel, it is called "bifurcation aneurysm". Aneurysms originating from the anterior vessels of the brain are called "aneurysm of anterior circulation" and those originating from the posterior veins of the brain are called "aneurysm of posterior circulation".How is Aneurysm Diagnosed?
Aneurysm is diagnosed by some special imaging methods.- Computed tomography angiography (CTA)
- Magnetic Resonance Angiography (MRA)
In these methods, computerized tomography or magnetic resonance images obtained by administration of medicine through arm vein are converted into a vessel image by a special program. These methods usually allow imaging and diagnosis of aneurysms larger than 3 mm.
Angiography
The most advanced method in vessel imaging that provides detailed information is catheter angiography. In this method, which is called DSA (digital subtraction angiography) in today's technology, a thin tube called catheter is introduced from the groin vein to reach the main vessels leading to the brain and a kind of dye is applied to obtain the image of the vessel. All of the features of the brain vessels can be examined in detail in these images, which can be obtained in different positions and even transformed into 3D vessel image. Before planning a treatment related to the vessels, a diagnostic brain angiography should be performed to examine the problems in the vein.Can a patient with aneurysm have another aneurysm?
The likelihood of having another aneurysm of a patient who had an aneurysm is between 15-20%.What are the findings of unruptured aneurysm?
Unruptured aneurysms usually do not cause any finding. Often, they are detected by chance in brain imaging performed for another reason, whereas some aneurysms grow silently, compressing nerves or other formations around them and causing their function to fail so they can be diagnosed. To a lesser extent, some large or giant aneurysms are partially diagnosed because a clot forms inside them, a part of this clot breaks off and occludes a vein, leading to certain symptoms.Why does aneurysm bleed?
It's not possible to fully understand which factor plays a role in bleeding of aneurysm or when an aneurysm will bleed. However, the causes that increase the probability of bleeding are clear:- Elevated blood pressure increases bleeding risk.
- Lifting heavy items or straining may increase the pressure in the brain vessel and cause aneurysm to bleed.
- Severe emotional storms (sadness, anger) that increase blood pressure increase the risk of bleeding.
- Certain medications (ephedrine, amphetamine, dietary drugs) and the use of substances such as cocaine increase the risk of bleeding of aneurysm.
- Smoking increases the risk of bleeding.
What is the likelihood of rupture of an unruptured aneurysm?
There is no clear answer to this question. This issue shows great similarity with another current issue in Turkey: Earthquake. If we make analogy; having an aneurysm in our brain is like sitting on a fault line. Just as it is not possible to know when a fault line will cause an earthquake and what the intensity of that earthquake will be, it is not possible to know when an aneurysm will rupture and at what intensity.Certain characteristics of aneurysm give an idea about the extent of the risk of bleeding. It is possible to have an idea about the possibility of bleeding of an aneurysm by looking at its characteristics such as size, shape and location; but this is not certain. If an aneurysm bleeds, it is highly likely that it will bleed again soon. Therefore, it should be treated as soon as possible.
What does aneurysm bleeding cause?
Inside the skull, the brain and the vessels that feed the brain are inside a fluid (cerebrospinal fluid) and there is a membrane surrounding that fluid. Aneurysm-induced cerebral hemorrhage is the mixing of blood into the fluid as a result of the rupture of the vessel in that fluid (subarachnoid hemorrhage). In the case of bleeding into the cerebrospinal fluid, the brain may respond to that in various ways:- Sudden death occurs in about 20% of bleeding patients. (An important part of the events where the person is said to have died suddenly or been found dead in their bed are patients who died as a result of a brain hemorrhage.)
- It causes a very severe headache that lasts for several hours or days. Patients often describe this pain as "the most severe headache in my life".
- It may cause nausea, vomiting.
- It causes severe pain in the neck and back of the neck and neck movements are restricted.
- Tendency to fall asleep or coma may develop.
- If there is partial hemorrhage into the brain tissue, loss of strength in arms and/or legs, impaired speech or impaired cooperation, loss of vision or seizure may occur.
Which damages does aneurysm bleeding cause in the brain?
The risk of death in aneurysm bleeding is approximately 50%. The likelihood of having moderate or severe disability varies between 20 and 35%. 15-30% of patients fully recover or recover from this condition with mild disability. 15-20% of patients who had a cerebral hemorrhage due to aneurysm may develop "vasospasm" (constriction of blood vessels due to mixing of blood into the cerebrospinal fluid). Due to this constriction of the vessels, feeding of the brain can be impaired and brain damage develops.Other adverse events that may develop in aneurysm-induced cerebral hemorrhage are ”hydrocephalus" (dilation of fluid-filled spaces in the brain) and respiratory distress. Heart and lung problems, which may develop due to brain damage, can also cause other organ damage in the body.
Does treatment of ruptured aneurysm help to treat brain damage?
No. If brain damage has occurred due to aneurysm bleeding, treatment of the aneurysm does not help to remedy this damage. The aim of treatment of ruptured aneurysm is to prevent rebleeding and brain damage or death that may occur due to this bleeding. In the case of brain damage caused by bleeding, the method recommended for acquisition of lost functions is rehabilitation.
How is aneurysm treated?
Aneurysm cannot be treated with medication; a surgical intervention is required. There are two main methods: clipping with open surgery or endovascular treatment (treatment applied through the vein without opening the skull).How is clipping of aneurysm with open surgery performed?
The operation is performed under general anesthesia. A section is removed from the skull, in a location and width, in accordance with the site of aneurysm and the surgeon's preference. Under the microscope, the surgeon advances through the spaces and folds around the brain, reaches the vein with aneurysm and progresses up to the section with the aneurysm of this vein.The place where the aneurysm joint the normal vein is prepared by various surgical techniques and a clip (one or several) is placed on the neck of the aneurysm. Meanwhile, in order to prevent probable aneurysm bleeding, it may be necessary to close the main vein with a temporary clips. After location and position of the clip are checked, the surgeon turns back using the route they have used to reach that site, sutures brain membrane again and closes the opening formed in the skull, and the operation is terminated. After the operation, the patient is taken to the intensive care unit and then transferred back to normal service when s/he reaches the appropriate conditions.
How is aneurysm treated with closed method (by endovascular route)?
The procedure should be performed under general anesthesia. The purpose of general anesthesia is not possible pain or ache the patient may have during the procedure. That the patient or his/her head mustn't be moved even by 1 mm during this treatment, which will last for one or several hours. At the same time, an anesthesiologist controls the patient's vital functions such as heart and lung functions during treatment of the brain, which increases patient safety.The patient's groin areas are stained for sterilization, then the patient is draped in a sterile fashion and a small opening is left in the groin areas. A needle is introduced through the artery in the groin and a small inlet, called an “introducer”, is placed in this segment of the artery. This 2 mm-diameter tube usually has a valve on its outer end and completely prevents bleeding out during the procedure. Under imaging guidance, the surgeon advances with a long and thin tube, called a catheter, and manages to reach the vessel with aneurysm in a short period of time. Through this tube, which is called a "guide catheter", a much thinner second tube (a microcatheter measuring about 0.5 mm in diameter) is introduced by the surgeon, who then proceeds with that tube. Using that microcatheter, the surgeon enters the aneurysm (in the company of imaging) and the aneurysm is filled by forming a ball with very soft wire spirals, called a "coil". The aim is to prevent blood from entering the aneurysm. During the procedure, dye injections are performed intermittently from the main vein to check how much the aneurysm has been filled, whether blood has entered into it, and the state of the adjacent vessels. During this process, a balloon may be used to control blood flow in the vessel or to ensure that the coils placed in the aneurysm coil up properly. Using a very small balloon (max 4 mm in diameter) fixed to the tip of another microcatheter, the surgeon advances through the guide catheter and reaches a site adjacent to the aneurysm to use it. Temporary inflation of this balloon shows the effect of the temporary clip in open surgical technique.
If the aneurysm neck is wide, a special stent may be placed in this part of the vessel in order to prevent the coils placed in the aneurysm from overflowing into the main vessel. If the aneurysm is too large and its neck is wide, it may be necessary to place a special stent with a tightly woven mesh called "a flow diverter stent" to this part of the vessel where the aneurysm is located.
How does the healing process develop after aneurysm treatment?
In unruptured aneurysms; open surgery patients are usually discharged within 1 week. Complete recovery can take several weeks to several months. Patients who are treated with endovascular treatment are usually discharged within 1-2 days. They completely return to normal life within a maximum period of 1 week.In ruptured aneurysms; regardless of the treatment method, the risky process continues for a while even if the treatment has been extremely successful.
Complications that may develop due to the effect of bleeding may be effective for approximately 3 weeks following bleeding and risk life. If this process is overcome without damage, it may take many months for the patient to fully heal.
Which complications may develop in the case of ruptured aneurysms?
If the aneurysm ruptures, there may be 2 main problems, as mentioned above;Vasospasm: It is a vein constriction that may develop if blood is mixed with the fluid where brain and vessels are located. Narrowing of the vessel due to contraction limits blood flow through it so the brain tissue fed by the contracting vessel does not get enough blood, which results in edema and/or damage due to lack of blood supply. If the vasospasm is detected early, its treatment will produce better results. In addition to some medications and treatments such as lowering the pressure by partially draining the cerebrospinal fluid with a needle or catheter, advanced techniques such as reaching that region through the vessel by angiography method and application of balloon or medication to expand the vessel may also be performed.
Hydrocephalus: It is the expansion of fluid-filled cavities, which are normally present in the brain, due to the deterioration of the circulation with the effect of blood. This may cause the brain to become compressed in the skull and deteriorate its blood supply. If hydrocephalus develops, by a relatively easier operation, it is possible to transfer the excess fluid accumulated to a cavity (thoracic or abdominal cavity) outside the skull by placing a tube called a shunt inside such cavities.
Which method is better for treatment of aneurysm?
Both open surgical clipping operation and closed (through the vessel) treatment method, called endovascular treatment, which are applied to treat brain aneurysms, have been proven to be effective and their long-term results are reliable. The important point in this selection is to determine which method is better suited for the patient and the aneurysm.The decision should be made according to aneurysm location, size, its relationship with neighboring vessels, its relationship with neighboring brain tissues, flow characteristics of this part of the vessel, the general condition of the patient, whether the patient has other diseases or not. A widespread belief today is choosing the endovascular treatment (closed treatment) in treatment of aneurysm, if it is possible to do it. In cases where endovascular treatment is not available, open surgical clipping operation is performed. As a result of this development, recently, attempts have been made to perform treatment by closed method in the neurosurgical community. Endovascular treatment of brain aneurysms (closed method) has been done by neuroradiologists for many years.