How are incidental Brain Aneurysms managed?

Brain aneurysms are sometimes found incidentally in patients who have imaging scans for another reason. The questions that come immediately to the patient's and doctor's mind are

Are these patients at high risk of subarachnoid hemorrhage? 

When should they see a stroke specialist, and should incidental aneurysms always be treated? 

What is the risk of an unruptured brain aneurysm?

Rupture risk assessment is complex and depends on many factors. When an aneurysm is found incidentally, it is recommended that the patient consult a Vascular Neurosurgeon for evaluation and discussion of risk and treatment options.

While there is no concrete data from literature, 7 mm is generally considered the outer limit of a “small” aneurysm.Lesions smaller than 7 mm carry between 0.5 to 5 percent risk of rupture in the next five years, while a 12-mm aneurysm has a risk as high as 12 percent and a 25-mm lesion, 50 percent.

Aneurysms located on certain arteries carry more risk of rupture than others. Those located on the anterior communicating artery, posterior communicating artery and the posterior circulation i.e., vertebro-basilar system have a higher risk of rupture than those located elsewhere. Aneurysms with certain morphologic features, such as those containing “daughter sac" may have higher risk over time. Finally, 20 to 30 percent of patients with aneurysms have more than one lesion. This increases rupture risk, especially if one has ruptured previously.

How common are unruptured Brain Aneurysms?

Approximately 3 percent of the population has unruptured intracranial aneurysms. Most are asymptomatic. Patients with severe, sudden, acute-onset headache, often described as “the worst headache of my life,” may have a ruptured aneurysm, especially if they also have stiff neck, nausea, vomiting and syncope. These patients should go to the emergency department immediately.

Patients who recently had severe headache and stiff neck but did not seek treatment may have had a sentinel subarachnoid hemorrhage.These patients have 50 percent risk of a second, potentially fatal hemorrhage in the next 30 days. These patients should also go to the emergency department immediately.

Unruptured aneurysms should also be suspected in patients with:

• Unusually severe headache with acute onset, including associated with sexual activity
• Drooping of one eyelid
• Blurred or double vision

Should patients be screened?

The incidence of harboring a brain aneurysm is about 9% in patients who have two or more one first-degree relative with an aneurysm, and these patients should be screened for aneurysms with magnetic resonance angiography or CT angiography. Patients with certain genetic diseases such as autosomal dominant polycystic kidney disease should also be screened.

Should unruptured Brain Aneurysms be treated?

The question of whether and when to treat an unruptured brain aneurysm is highly individualized and depends on a number of patient and aneurysm factors.

Observation or Watchful Waiting

Patients whose aneurysms are not treated but observed, should have good blood pressure control and stop smoking, if they smoke. Excessive alcohol consumption should also be avoided, although there is no evidence in this regard. These lifestyle changes decrease the risk of developing an aneurysm, rupture and treatment complications.

Patients with small, asymptomatic aneurysms should be screened with magnetic resonance angiography, with repeat screening in a year. If the aneurysm is stable, they can be followed up with serial MRAs at two and three years. If an aneurysm grows or changes shape or the patient exhibits mass effects or cranial nerve symptoms, the risk goes up and such an aneurysm should be considered for treatment.

Endovascular coiling and Surgery

The main interventions for an unruptured aneurysm are surgical clipping and endovascular coiling or flow diversion. Risk of treatment depends on aneurysm complexity, patient health and other factors. The decision for surgical clipping or endovascular therapy should be discussed with the patient by an experienced vascular neurosurgery team. Depending upon the nature of the aneurysm and experience of the treating vascular neurosurgeon, surgical clipping and endovascular therapy should be chosen.

The usual duration of stay for a patient with unruptured brain aneurysm undergoing surgery at our center is 8 days whereas that for a patient undergoing endovascular therapy is about 3-4 days.

Subarachnoid Hemorrhage

What is Subarachnoid Hemorrhage (SAH)?

The brain is surrounded by three layers of coverings. All the important arteries supplying blood to the brain and veins draining impure blood from the brain run between these three layers. Bleeding into the subarachnoid space is known as Subarachnoid Hemorrhage (SAH).

What causes SAH?

The most common cause of SAH is head injury. However, the most devastating cause of SAH is due to rupture of a brain aneurysm. Often the bleeding stops, and the person survives. In more serious cases, the bleeding may cause brain damage with paralysis or coma. In the most severe cases, the bleeding leads to death. Bleeding into the cerebrospinal fluid may lead to acute increase in the intracranial pressure. Other conditions that can cause SAH are vascular malformation of the brain and venous stroke

What are the symptoms of SAH?

The main symptom is a sudden severe headache and neck pain. Other symptoms include

• Seizures
• Confusion
• Irritability
• Sensitivity to light
• Decreased vision
• Nausea
• Vomiting
• Loss of consciousness

What to do when someone is diagnosed with SAH?

Immediate referral to a center with neurosurgery and neurointerventional facilities is paramount to appropriate diagnosis and management of the patient with SAH and prevent brain damage. If your aneurysm is being clipped, a craniotomy is performed and the aneurysm is closed. A craniotomy involves opening the skull to expose the area of involvement. Alternatively, endovascular coiling involves introducing a long catheter through one of the arteries in the groin, navigating it all the way into the aneurysm in the brain and closing the aneurysm using coils (thin threads made of platinum alloy).

If SAH causes a coma, treatment will include appropriate life support with artificial ventilation, protection of the airways, and placement of a draining tube in the brain to relieve pressure.

What are the complications of SAH?

• Remleiding from the aneurysm is a serious concern in a patient with aneurysm rupture. Hence, the aneurysm needs to be closed as soon as possible by either open surgery or endovascular therapy
• Bleeding into the CSF (cerebrospinal fluid) and in the space around the brain (subarachnoid space). The pool of blood forms a clot. Blood can irritate, damage, or destroy nearby brain cells. This may cause problems with body functions or mental skills.
• Blood from an aneurysm rupture can block CSF circulation. This can lead to fluid buildup and increased pressure on the brain. Because blood is spread around the base of the brain, the possibility of fluid buildup exists, causing hydrocephalus. The CSF containing spaces in the brain, called ventricles, may enlarge. It can make a patient lethargic, confused, or comatose. To stop fluid buildup, a drain may be placed in the ventricles. The tube is called a ventriculostomy, and often drains into a bag at the patient's bedside. This removes leaked blood and trapped CSF. If the hydrocephalus persists, the patient may require a ventriculoperitoneal shunt surgery to drain the CSF permanently.
• The blood around the base of the brain can also produce a problem called vasospasm. Vasospasm typically develops 5-8 days after the initial hemorrhage. Narrowing of the blood vessels can occur and at times not enough blood is supplied to the brain and a stroke may result. To treat vasospasm, blood pressure is often elevated with medicines. Certain medications are also given to try to reduce vasospasm. Finally, catheters can be introduced inside the artery in an attempt to use balloons or medications delivered to the vessel directly to open up these narrowed vessels. Vasospasm does subside over several days.

What is the outcome of SAH?

SAH survivors usually have a much longer recovery time than unruptured aneurysm patients, as well as more serious deficits. Symptoms are proportional to the degree of hemorrhage and the initial clinical condition. Patients who are comatose or semi-comatose after a hemorrhage have longer recoveries and have more significant neurocognitive problems as compared to patients with smaller hemorrhages or unruptured aneurysms.