What Is Subarachnoid Hemorrhage? Understanding Causes, Symptoms, and Treatment
Understanding Subarachnoid Hemorrhage: A Life-Threatening Neurological Emergency
Subarachnoid hemorrhage (SAH) is a severe type of hemorrhagic stroke characterized by bleeding into the subarachnoid space—the area between the brain and the thin tissues that cover it. This condition typically occurs when a blood vessel on the surface of the brain or at the base of the skull ruptures, releasing blood into the surrounding cerebrospinal fluid. While relatively rare compared to other forms of stroke, SAH is one of the most critical neurological emergencies due to its high mortality and long-term disability rates.
Primary Causes of Subarachnoid Hemorrhage
The leading cause of spontaneous subarachnoid hemorrhage is the rupture of a cerebral aneurysm— a weak, bulging spot in a brain artery wall. These aneurysms often develop over time and may remain undetected until they burst. Approximately 80% of non-traumatic SAH cases are attributed to aneurysmal rupture. Other less common causes include arteriovenous malformations (AVMs), which are abnormal tangles of blood vessels, as well as vasculitis (inflammation of blood vessels), bleeding disorders, and certain rare conditions like tumors or drug abuse.
Sudden Onset Symptoms: Recognizing the Warning Signs
One of the hallmark signs of SAH is a sudden, extremely intense headache—often described by patients as "the worst headache of my life." This thunderclap headache typically occurs without warning and may be triggered by physical strain, such as lifting heavy objects, straining during bowel movements, or even sexual activity. Alongside the headache, individuals frequently experience nausea, vomiting, neck stiffness, sensitivity to light, and confusion.
In more severe cases, neurological function deteriorates rapidly. Patients may quickly progress from drowsiness to lethargy, stupor, or even coma. Because SAH can lead to immediate brain damage or cardiac arrest, it stands out as the only cerebrovascular condition in neurology associated with sudden death. Immediate medical attention is crucial for survival and minimizing complications.
Diagnosis and Advanced Imaging Techniques
When SAH is suspected, rapid diagnosis is essential. Initial evaluation usually begins with a non-contrast CT scan of the head, which can detect blood in the subarachnoid space in over 95% of cases within the first 24 hours. If the CT scan is inconclusive but clinical suspicion remains high, a lumbar puncture may be performed to check for xanthochromia—yellowish discoloration of cerebrospinal fluid caused by the breakdown of red blood cells.
Once SAH is confirmed, identifying the source of bleeding becomes the next priority. Cerebral angiography, particularly digital subtraction angiography (DSA), is considered the gold standard for visualizing aneurysms and vascular malformations. In some cases, CT angiography (CTA) or MR angiography (MRA) may also be used for preliminary assessment.
Effective Treatments That Save Lives
Timely intervention significantly improves outcomes. The two primary treatment options for aneurysmal SAH are surgical clipping and endovascular coiling (also known as embolization). Clipping involves opening the skull and placing a metal clip at the base of the aneurysm to prevent further bleeding. Coiling, a minimally invasive procedure, involves threading a catheter through the arteries to the site of the aneurysm and filling it with platinum coils to block blood flow and reduce the risk of rebleeding.
Recent advances in neurointerventional techniques have made endovascular treatments increasingly preferred, especially for older patients or those with complex aneurysm locations. Additionally, supportive care—including blood pressure management, seizure prevention, and monitoring for complications like vasospasm—is vital during recovery.
Prevention and Long-Term Outlook
While not all cases of SAH can be prevented, managing risk factors such as uncontrolled hypertension, smoking, excessive alcohol consumption, and drug use (particularly cocaine and amphetamines) can significantly reduce the likelihood of aneurysm formation and rupture. Individuals with a family history of brain aneurysms may benefit from screening with MRA or CTA, especially if multiple relatives have been affected.
Survivors of SAH often face a challenging recovery process involving physical therapy, cognitive rehabilitation, and psychological support. Early detection, prompt treatment, and comprehensive follow-up care play key roles in improving quality of life and reducing the risk of recurrence.