Most Common Cause of Spontaneous Subarachnoid Hemorrhage: Ruptured Brain Aneurysms

Spontaneous subarachnoid hemorrhage (SAH) is a life-threatening medical emergency that demands immediate attention. Among the various causes, the most prevalent one is the rupture of an intracranial aneurysm. These aneurysms are not tumors but rather weakened areas in the walls of cerebral arteries, typically located along major blood vessels at the base of the brain. Over time, factors such as chronic high blood pressure and structural vessel wall defects can cause these weak spots to balloon out and eventually burst.

Understanding Intracranial Aneurysms

An intracranial aneurysm develops when a section of a blood vessel in the brain becomes thin and bulges outward due to hemodynamic stress. While many aneurysms remain asymptomatic and undetected, those situated in critical regions—especially within the Circle of Willis—are more likely to rupture. When this happens, blood spills into the subarachnoid space, which surrounds the brain and spinal cord, triggering a cascade of dangerous complications.

Symptoms and Immediate Clinical Presentation

The hallmark symptom of a ruptured aneurysm is a sudden, severe headache often described by patients as "the worst headache of my life." This abrupt onset of pain is frequently accompanied by nausea, vomiting, neck stiffness, photophobia, and in severe cases, loss of consciousness or seizures. Given the rapid progression of symptoms, early diagnosis is crucial for improving patient outcomes.

Diagnosis Through Neuroimaging

When SAH is suspected, non-contrast computed tomography (CT) of the head is the first-line diagnostic tool. It can detect blood in the subarachnoid space with high sensitivity, especially within the first 24 hours after the event. If CT results are inconclusive but clinical suspicion remains high, a lumbar puncture may be performed to check for xanthochromia in the cerebrospinal fluid—a sign of prior bleeding.

Potential Complications After Rupture

Aneurysm rupture doesn't just cause initial bleeding—it triggers secondary dangers. One of the most serious is cerebral vasospasm, which typically occurs 3 to 14 days post-hemorrhage. This narrowing of brain arteries can lead to delayed cerebral ischemia, resulting in stroke-like deficits or permanent neurological damage. Additionally, the leaked blood may form intracerebral hematomas, increasing intracranial pressure and further compromising brain function.

Treatment Options: Surgical vs. Endovascular Approaches

Once diagnosed, prompt treatment is essential to prevent rebleeding, which carries a significantly higher mortality rate. There are two primary interventions available:

1. Surgical Clipping (Open Craniotomy)

This traditional method involves opening the skull to access the aneurysm directly. A small metal clip is placed at the base of the aneurysm to stop blood flow into it. While this approach requires a larger incision and longer recovery time, it offers a durable, long-term solution and is generally less expensive than endovascular techniques.

2. Endovascular Coiling (Minimally Invasive Procedure)

In contrast, endovascular coiling is a less invasive option where a catheter is threaded from the groin up into the brain's arteries. Tiny platinum coils are then deployed into the aneurysm to promote clotting and prevent further bleeding. This method reduces physical trauma, shortens hospital stays, and speeds up recovery—but often comes with a higher upfront cost.

In recent years, advancements like flow diverters and stent-assisted coiling have further improved success rates for complex aneurysms. The choice between surgical clipping and endovascular therapy depends on multiple factors including aneurysm size, location, patient age, overall health, and institutional expertise.

Prognosis and Long-Term Outlook

Despite advances in neurocritical care, ruptured aneurysms remain highly dangerous. The overall mortality rate following SAH ranges from 30% to 50%, with many survivors facing long-term disabilities. Early detection, rapid intervention, and comprehensive rehabilitation play key roles in improving quality of life post-event.

To reduce risk, individuals with known risk factors—such as hypertension, smoking, family history of aneurysms, or polycystic kidney disease—should consider regular screening and adopt heart-healthy lifestyles. Controlling blood pressure, avoiding tobacco, and managing stress are vital preventive measures.

In conclusion, while spontaneous subarachnoid hemorrhage is a devastating condition, understanding its leading cause—the rupture of cerebral aneurysms—empowers both clinicians and patients to act swiftly and effectively. With timely diagnosis and appropriate treatment, survival and recovery rates continue to improve across modern healthcare systems.