BRAIN ANEURYSMS
Aneurysm is a ballooning that occurs as a result of the weakening of the artery wall in the brain and is often seen in the bifurcation areas of the vessels. This ballooned structure is more flimsy than a normal vein, and under some conditions it may rupture and cause bleeding into the brain, endangering life. Aneurysms may be due to congenital vascular maldevelopment, or may develop after high blood pressure, arteriosclerosis (atherosclerosis), infections (inflammation of the vessel) or head trauma. Aneurysms are usually located at the base of the brain and cause bleeding in the cerebrospinal fluid there. The annual bleeding risk of aneurysms is approximately 1%.
Aneurysm Types
Saccular (sac-shaped) aneurysms:The most common type of aneurysm is the large vessels at the base of the brain. It occurs in bifurcation areas. At these bifurcation points, the vessel wall is exposed to more pressure. This constant pressure may cause ballooning over time as a result of damage to the vessel wall. Saccular aneurysms develop over years, and therefore the risk of aneurysm rupture increases with age. We can compare this development of an aneurysm to the ballooning seen in the inner tubes used in vehicles in the past. Another important reason for the formation of aneurysms is the loss of elasticity of the vessel wall as a result of the deterioration of the vascular structure in older ages.
Fusiform (spindle-shaped) aneurysms:This aneurysm is a spindle-shaped expansion that includes a long section of the vessel. is seen as . These types of aneurysms may rupture and bleed, expand to a large extent and cause pressure on the surrounding brain tissue, or cause clotting and detachable debris from the brain causing blockage (embolism) in normal brain vessels, causing stroke-like complaints.
Mycotic (). Aneurysms (developing as a result of inflammation):They are rare and develop as a result of microbial disease of the vessel. They are generally pouch-shaped. Inflammation causes damage to the vessel wall, thus As a result of wall weakening, the risk of aneurysm formation and its rupture increases. It is often a complication of subacute bacterial endocarditis (known as 'heart rheumatism' in our society).
Traumatic (accidental) aneurysms: It is a type of aneurysm that develops after an accident in the brain blood vessels. The damaged vascular wall in the trauma area weakens and may subsequently rupture.
Prevalence and Frequency in the Society
The frequency of brain hemorrhage due to brain aneurysm is around 10-15 per 100,000 people a year. It can be assumed that an average of 10,000 people every year in our country are at risk of brain hemorrhage due to aneurysm. Approximately 1/3 of these patients die before they can contact any health institution. The mortality rate in bleeding patients who can apply to a healthcare facility is between 25-40%. Therefore, nearly half of the patients whose aneurysm bleeds die. An important point here is the early diagnosis and treatment of brain aneurysms that have not yet bleed but still put the patient at risk.
Aneurysms can be seen in all age groups, but the frequency is gradually increasing in those aged 25 and above. Its prevalence is most common between the ages of 50-60 and it is 3 times more common in women than in men. Having a family history of aneurysms increases the risk of having aneurysms in other family members. Having more than one aneurysm at the same time in a person increases this risk even more.
Although the exact cause of aneurysm is not known, it is known that many factors play a role in its development: 1) Hypertension (high blood pressure); 2) Smoking/nicotine use; 3) Diabetes; 4) Excessive alcohol consumption; 5) Congenital (genetic) predisposition; 6) Damage to blood vessels (especially arteriosclerosis) or trauma; and 7) Some infections.
Symptoms/Warning Signs
Some warning signs may occur in patients with aneurysm rupture/bleeding:
- Sudden and severe headache radiating upwards from the back of the head. Sometimes pain is described as if a bomb exploded in the head.
- Nausea and vomiting
- Blurred or double vision
- Sensitivity to light (photophobia)
In most people with unruptured aneurysm There may be no symptoms. Some or all of the following symptoms may be seen in a small group of patients:
- Paralysis of the optic nerves (such as drooping eyelid, inability to move the eye easily)
- One-sided dilated pupil
- Double vision, pain behind or above the eye
- Persistent headache in one area
- Progressive weakness and drowsiness
Risks and Complications
When aneurysms rupture, subarachnoid hemorrhage (SAH) often develops (between the brain and the thin membrane of the brain). Blood passing from the vein to the subarachnoid space at high pressure may accumulate there and cause pressure on the brain. Bleeding may also occur inside the brain; Blood elements can also reach the spinal cord environment, which has lower pressure.
Bleeding from the aneurysm may sometimes occur in the form of leakage; In this case, a small clot may form at the leak point and stop the bleeding, and the patient may survive. However, this process caused by the clot does not prevent the risk of rebleeding; With each additional bleeding, life becomes more endangered and the likelihood of survival decreases. The cause of most spontaneous SAHs is aneurysms.
Exactly determining the location, size and configuration of the aneurysm is a critical point in its treatment and therefore prevention of rebleeding. The probability of bleeding again after a bleed is around 20% for the first 14 days. As mentioned above, aneurysm bleeding is fatal at rates of up to 50%. It also causes permanent neurological disorders in 25% of living patients. In addition to mental functions, impairment of all body functions (for example, partial paralysis) may occur. In more serious cases, bleeding can cause severe damage to brain cells and put the patient into a coma.
If the aneurysm is large, it can cause damage by causing pressure on the surrounding brain tissue without bleeding. Also, clots in large aneurysms It may develop and pieces that break off may cause many strokes.
Blood leaking around the brain may cause narrowing (vasospasm) in the vessels. This may cause a decrease in blood flow to the brain tissue and therefore a stroke. Vasospasm usually develops 5-8 days after bleeding. Treatment is quite difficult and may endanger the patient's life.
Blood leaking from a ruptured aneurysm can block the cerebrospinal fluid (CSF) circulation, causing the condition we call hydrocephalus (excessive fluid accumulation in the brain). In this case, excessive fluid may accumulate in the spaces in the brain called ventricles, causing intracranial pressure to increase. To prevent this fluid increase, a drain is placed in these cavities to remove the accumulated fluid and leaking blood.
Aneurysm bleeding may also cause brain edema or swelling. This situation affects brain functions and causes very serious problems. Swelling and increased pressure of the brain tissue damages the brain tissue. Cerebral edema can cause pressure on blood vessels, slowing down blood flow to the brain.
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