What is a Brain Aneurysm?

A brain aneurysm, also called a cerebral aneurysm or intracranial aneurysm, is a bulge or ballooning in a weakened area of a brain artery. The most common type is a saccular aneurysm, sometimes called a berry aneurysm, which forms like a small pouch on the side of a blood vessel.

Many brain aneurysms are unruptured, meaning they have not leaked or burst. Some unruptured aneurysms are found during imaging for another reason and may not cause symptoms. A ruptured aneurysm is different and is a medical emergency because it can cause bleeding around the brain, called subarachnoid hemorrhage.

De Novo Brain & Spine evaluates adult patients with suspected or known brain aneurysms to help determine the appropriate next step. Evaluation may include neurological examination, review of CTA, MRA, MRI, CT imaging, catheter angiography, monitoring recommendations, emergency referral when needed, or coordination with neurovascular and stroke specialists.

Common Signs and Symptoms

Brain aneurysm symptoms depend on whether the aneurysm is unruptured, leaking, or ruptured. Many unruptured brain aneurysms do not cause symptoms, especially when they are small.

Possible symptoms of an unruptured brain aneurysm may include:

• Headache
• Pain above or behind one eye
• Blurred vision or double vision
• Dilated pupil
• Drooping eyelid
• Facial numbness, tingling, or weakness
• Seizure in some cases
• Difficulty with eye movement if nearby nerves are affected

Symptoms of a ruptured brain aneurysm may include:

• Sudden, severe headache, often described as the worst headache of a person’s life
• Nausea or vomiting
• Stiff neck
• Sensitivity to light
• Blurred or double vision
• Confusion or decreased alertness
• Seizure
• Fainting or loss of consciousness
• Sudden weakness, numbness, speech difficulty, or other stroke-like symptoms

Seek emergency medical care or call 911 for a sudden severe headache, first-time seizure, loss of consciousness, sudden vision loss, sudden weakness, sudden speech difficulty, severe confusion, or rapidly worsening neurological symptoms.

What Causes This Condition?

A brain aneurysm forms when part of an artery wall becomes weak and begins to bulge. The exact reason an aneurysm forms is not always known. A brain aneurysm diagnosis does not usually mean that the patient did something to cause it.

Factors that may increase the risk of developing or rupturing a brain aneurysm include:

• High blood pressure, also called hypertension
• Cigarette smoking
• Family history of brain aneurysm, especially in first-degree relatives
• Prior aneurysmal subarachnoid hemorrhage
• Certain inherited connective tissue disorders
• Polycystic kidney disease
• Brain arteriovenous malformation, also called brain AVM, in selected cases
• Prior injury or trauma to a blood vessel
• Certain bloodstream or vessel infections in rare cases
• Aneurysm size, location, shape, and growth over time

These are risk factors, not guaranteed causes. Treatment planning depends on the aneurysm’s size, shape, location, rupture status, symptoms, medical history, imaging findings, and the patient’s overall health.

How It Is Diagnosed?

A brain aneurysm cannot be diagnosed by symptoms alone. Diagnosis usually requires medical history, neurological examination, and vascular imaging of the brain.

Common diagnostic steps may include:

• Medical history and neurological examination to evaluate headache pattern, vision, eye movement, strength, sensation, reflexes, speech, coordination, balance, and alertness
• CT scan of the head to look for bleeding when a ruptured aneurysm or subarachnoid hemorrhage is suspected
• CT angiography, also called CTA, to evaluate the brain arteries and look for an aneurysm
• MRI of the brain to evaluate brain structures and related findings
• MR angiography, also called MRA, to evaluate blood vessels without traditional catheter angiography
• Digital subtraction angiography, also called cerebral angiography or catheter angiography, when more detailed imaging of the aneurysm and surrounding blood vessels is needed
• Lumbar puncture, also called a spinal tap, in selected cases when subarachnoid hemorrhage is suspected but initial imaging does not clearly show bleeding
• Comparison with prior imaging to determine whether an aneurysm is stable, enlarging, or changing in shape

The goal of diagnosis is to determine whether an aneurysm is present, whether it has ruptured, and whether monitoring or treatment should be considered.

Treatment Options

Brain aneurysm treatment depends on whether the aneurysm is unruptured or ruptured, as well as its size, shape, location, symptoms, growth pattern, rupture risk, treatment risk, and the patient’s overall health. Not every unruptured brain aneurysm requires immediate treatment.

Treatment options may include:

• Observation with repeat imaging for selected unruptured aneurysms that appear stable and have a lower estimated risk of rupture
• Risk factor management, including blood pressure control and smoking cessation when applicable
• Emergency treatment for ruptured aneurysm when subarachnoid hemorrhage is present
• Microsurgical clipping, a procedure in which a neurosurgeon places a small clip across the neck of the aneurysm to block blood flow into the aneurysm sac
• Endovascular coiling, a catheter-based procedure in which coils are placed inside the aneurysm to reduce blood flow into the aneurysm
• Stent-assisted coiling in selected aneurysms when additional support is needed to keep coils in place
• Flow diversion, a catheter-based treatment that places a stent in the parent artery to redirect blood flow away from the aneurysm in selected cases
• Treatment of hydrocephalus or increased pressure, such as ventricular drainage or shunt placement, when bleeding blocks cerebrospinal fluid flow
• Neurocritical care after rupture to monitor for complications such as vasospasm, hydrocephalus, seizures, or stroke
• Rehabilitation and supportive care when a ruptured aneurysm causes weakness, speech problems, balance issues, cognitive changes, or other neurological effects

Surgery or endovascular treatment is not appropriate for every aneurysm. The safest plan depends on a careful comparison of the aneurysm’s rupture risk, the risks of treatment, and the patient’s individual medical condition.