What is Brain aneurysm?
Brain aneurysm or cerebral aneurysm is a condition involving the cerebrovascular system characterized by weakness in the cerebral artery or vein wall resulting to localized ballooning or dilatation of the blood vessel. There are three types of aneurysms depending on shapes: saccular, berry and fusiform.
Saccular aneurysms are out pouching of the vessels to one side and are the most uncommon type of aneurysm. Berry aneurysm resembles a berry while fusiform is an out pouching in all the sides of the blood vessel. Brain aneurysms may be small (less than 15mm), large (15 to 25 mm), giant (up to 50 mm) or super giant (larger than 50 mm). The most common site of brain aneurysms is in the Circle of Willis, located on the base of the brain.
Symptoms and Signs
Cerebral aneurysms often are asymptomatic unless it has ruptured. However, some symptoms may be felt prior to the rupture of aneurysm. These include:
Unusual and sudden severe headache
Severe headache is brought about by the increased intracranial pressure, which compresses the underlying nerve endings in the area.
Nausea and Vomiting
Nausea and vomiting may also be experienced because of compression of the vomiting center or the medulla oblongata by the enlarging aneurysm. Patients may experience projectile vomiting.
Patients often experience burring of vision because of an increase in the pressure of the optic nerve.
Loss of consciousness
Elevation of the intracranial pressure may also cause affectation of the mentation, which may cause lethargy or stupor. Rupture of the aneurysm causes a leak of blood in the subarachnoid space. This condition is known as subarachnoid hemorrhage. Small aneurysms may cause minimal bleeding, but super giant aneurysms can cause severe hemorrhage.
The more blood is collected in the subarachnoid space, the more severe the symptoms will be. Bleeding on the brain itself may also happen, which may lead to hemorrhagic stroke. When rupture happens, patients often experience the following symptoms:
Sudden severe headache
Headache becomes intensified when the aneurysm ruptures because of a more severe elevation of the intracranial pressure.
The bleeding causes a specific area of the brain to be unoxygenated leading to death of the brain cells. Paralysis is usually contralateral. When the left side of the brain is affected, the right side of the body is affected and vice versa.
Problems with speech
Following a hemorrhagic stroke, the affectation of the speech center in the cerebral cortex also leads to slurring of the speech.
Hemianopsia is the loss of one half of the outer vision in the affected area of the body. Because of this, patients are not able to see on the peripheral areas of vision in one side only.
Unoxygenation and death of the brain cells may also cause seizures that further deplete oxygen in the brain.
Coma is the final result of ruptured aneurysm and may potentially cause death.
Brain Aneurysm Causes
There are a lot of causes of cerebral aneurysm, including:
- Congenital defects
Defects on the smooth muscles of the blood vessels lead to weakening and aneurysm formation. Almost 90% of aneurysms are congenital.
- Atherosclerosis and hypertension
Prolonged high pressure on the blood vessels causes the wall to weaken and out-pouch.
- Head trauma
High impact trauma in the head causes the blood vessels to weaken if not completely severed.
Recent research has also found genetic predisposition for aneurysms.
Brain Aneurysm Treatment
Treatment of brain aneurysm includes medical and surgical approaches. Medical approaches involve the emergency management of the increased intracranial pressure and respiratory depression. Medical treatments include:
Patients may require oxygen therapy or mechanical ventilation to support the respirations. Affectation of the brain causes the depression of the respiratory center that can lead to respiratory compromise.
Osmotic diuretics such as mannitol may also be given to reduce cerebral edema.
Surgery and Recovery
Surgery is the treatment of choice for cerebral aneurysms to establish vascular integrity and prevent further hemorrhage. There are different types of surgery that may be employed including:
Surgical clipping involves the placement of a clip on the base of the aneurysm to prevent further out pouching or dilation of the aneurysm. The procedure is done by performing a craniotomy to expose the aneurysm in order to place the clip. Surgical clipping prevents the recurrence of the aneurysm.
Surgical clipping was traditionally done through craniotomy, but a group of physicians has started to perform the procedure through a lesser invasive approach in 2009. This involves an endoscopic endonasal approach. The surgical technique reaches the aneurysm through the nose and is especially effective in aneurysm located at the base of the brain.
Endovascular coiling involves the insertion of platinum coils in the aneurysm. This is done by inserting the coil through the femoral artery, passing through the aorta and the arteries in the brain until it reaches the aneurysm. The platinum coil functions by initiating thrombotic reaction or clotting in the aneurysm to prevent further bleeding. The procedure only involves a small incision in the femoral area for the insertion of the catheter containing the platinum coil.
Recovery from both procedures is equal with risks and deaths also at the same rate. However, patients with clipping have a lower rate of recurrence. On the other hand, the rate of rebleeding is 7% lower in coiling procedure. In summary, there is shorter recovery period for patients with coiling.
Prognosis and Survival Rate
Prognosis really depends on the location and severity of the aneurysm. Some individuals recover from the condition and may not manifest neurologic deficits. However, up to 50% of survivors may suffer from permanent neurologic deficits. Individuals with ruptured aneurysm have poorer prognosis with 50% of cases can die within 30 days of rupture. Older patients also have less survival rates.
Preventing brain aneurysm involves preventing its causative factors. Preventions include:
- Quitting smoking
- Monitoring the blood pressure
- Avoiding foods high in sodium and saturated fats
- Exercising regularly
- Eating a healthy diet
- Limiting caffeine intake
- Limiting use of aspirin
- Avoid straining by preventing constipation