What is a Cerebral Aneurysm?
A cerebral aneurysm is a condition where the wall of an artery in the brain becomes abnormally thin or weak in certain areas due to atherosclerosis, chronic high blood pressure, or arterial inflammation. This causes the artery wall to bulge out like a sac.
If a cerebral aneurysm is not detected and properly treated, it may enlarge and eventually rupture, leading to a subarachnoid hemorrhage, which is a medical emergency requiring urgent treatment.
Dangers of Cerebral Aneurysm
Cerebral aneurysms often show no symptoms in the early stages. Most patients are unaware of the condition until the aneurysm ruptures, causing bleeding in the subarachnoid space (Subarachnoid Hemorrhage; SAH), which is a severe medical emergency. The effects include:
- Blood leaking from the ruptured aneurysm rapidly increases intracranial pressure, causing elevated brain pressure and severe brain tissue damage.
- The leaked blood triggers severe vasospasm in other cerebral arteries, leading to insufficient blood supply to parts of the brain, resulting in ischemia or paralysis later on.
- Blood in direct contact with brain tissue is toxic to brain cells, causing inflammation and rapid brain cell death.
Because of this, the mortality rate is high, around 30-50%, and survivors often face a high risk of permanent disability due to brain damage. Additionally, other complications may occur, such as brain swelling, nervous system infections, or seizures after bleeding, all of which require close monitoring as they can affect recovery and long-term quality of life.
Warning Signs Before a Cerebral Aneurysm Ruptures
It is important to understand that most unruptured cerebral aneurysms do not show any warning signs and are often found incidentally during brain scans for other reasons. However, some patients may experience warning symptoms, which can be divided into two main types:
Symptoms from Nerve or Brain Tissue Compression
These usually occur when the aneurysm grows large enough to press on nearby structures, especially nerves controlling vision and facial movement. Symptoms may include:
- Pain around or behind the eye, usually localized and continuous.
- Visual disturbances such as double vision or blurred vision.
- Drooping eyelid on one side.
- Dilated pupil, noticeable when one pupil is significantly larger than the other.
- Numbness or weakness on one side of the face.
These compression symptoms are usually constant and not intermittent, so they should not be ignored as they may be early signs leading to a severe and life-threatening brain emergency.
Sentinel Headache
Sentinel headache is a sudden and severe headache caused by a small leak of blood from a cerebral aneurysm into the subarachnoid space, where cerebrospinal fluid flows. This usually occurs days or weeks before a full aneurysm rupture and subarachnoid hemorrhage, which can be life-threatening.
Typically, the sentinel headache lasts only a few days before gradually subsiding, which may lead patients to mistake it for a common headache. However, it can be a warning sign that the aneurysm is likely to rupture within days to weeks. Patients experiencing additional symptoms such as nausea, vomiting, light sensitivity, double vision, stiff neck, or sudden neurological symptoms like weakness on one side, numbness, or difficulty speaking should seek immediate medical attention.
Diagnosis of Cerebral Aneurysm
The choice of diagnostic method generally depends on the initial symptom assessment as follows:
Screening or Suspected Unruptured Aneurysm
For high-risk individuals without symptoms, such as those with two or more family members with cerebral aneurysms or those with symptoms possibly caused by aneurysm compression, doctors use non-invasive methods like Magnetic Resonance Angiography (MRA), which can detect small aneurysms effectively.
Diagnosis When Ruptured Cerebral Aneurysm is Suspected
For patients presenting with sudden severe headache as a medical emergency, diagnosis must be rapid using the following methods:
- Brain CT Scan is highly effective in detecting brain or subarachnoid bleeding, a key sign of ruptured cerebral aneurysm. Small or older bleeds may be less visible.
- CT Angiography (CTA) combines CT scanning with contrast injection through a vein to create 3D images of cerebral blood vessels. This helps doctors see the location, size, shape, and characteristics of the aneurysm and detect vessel narrowing or blockage.
- Lumbar Puncture is used when other tests do not show bleeding but symptoms strongly suggest it. It detects red blood cells in the cerebrospinal fluid to confirm subarachnoid hemorrhage.
Confirmatory Tests and Treatment Planning
Cerebral Angiography involves injecting contrast dye into the cerebral arteries to clearly visualize blood flow and aneurysm characteristics in all dimensions. It is usually performed to confirm other test results or plan treatment. In some cases, endovascular coiling can be done immediately during this procedure.
Treatment of Cerebral Aneurysm
Treatment depends on the size, location, complexity of the aneurysm, symptoms, risk factors, and overall patient health. The main treatment methods include:
- Aneurysm Clipping is an open craniotomy surgery to access the aneurysm and place a small metal clip at its neck to prevent blood flow into the fragile sac, effectively preventing rupture. This method is suitable for large, complex aneurysms or those unsuitable for other treatments. It has a low recurrence rate but carries risks such as infection, bleeding, or brain and nerve injury, and requires longer recovery time compared to less invasive methods.
- Endovascular Coil Embolization is a minimally invasive treatment where a small catheter is inserted through an artery in the groin or wrist to the aneurysm site. Flexible platinum coils are released into the aneurysm to induce clotting, preventing blood flow into the sac and future enlargement or rupture. This method causes less pain, faster recovery, and lower risk than open surgery but may require periodic follow-up with MRA or CTA due to possible recanalization.
- Brain Surgery also includes procedures to manage common complications such as brain hemorrhage, where surgery may be needed to drain blood and reduce pressure to prevent brain damage. In cases of brain swelling, a cerebrospinal fluid drainage tube may be inserted to lower intracranial pressure.
A cerebral aneurysm can be immediately life-threatening if it ruptures. If you or someone close to you is at risk or experiences a sudden severe headache unlike any before, especially the worst headache of their life (thunderclap headache), seek medical attention immediately.
At Phyathai Phaholyothin Hospital, we have a specialized team of neurosurgeons and vascular surgeons equipped with advanced technology such as CT Scan, CT Angiography, MR Angiography, and Cerebral Angiography, enabling fast and accurate diagnosis. We offer standard treatments including aneurysm clipping and endovascular coiling to improve treatment outcomes and help patients return to a quality life.
Dr. Theerapap Kitchawijit
Neurologist
Phyathai Phaholyothin Hospital
