Common Complications of Subarachnoid Hemorrhage: What You Need to Know

Subarachnoid hemorrhage (SAH) is a serious medical condition that affects thousands of people worldwide each year. While it can result from trauma, spontaneous SAH—often caused by the rupture of a cerebral aneurysm—is particularly dangerous due to its high risk of life-threatening complications. Early recognition and management of these complications are crucial for improving patient outcomes. The most common complications following subarachnoid hemorrhage fall into three major categories: rebleeding, cerebral vasospasm, and hydrocephalus.

1. Rebleeding: A Critical Early Risk

Rebleeding is one of the most immediate and dangerous complications after an initial SAH. When a brain aneurysm ruptures for the first time, the risk of it bleeding again is significantly elevated—especially within the first 24 hours. This second bleed can lead to rapid neurological deterioration, including worsening or sudden loss of consciousness. In some cases, patients may experience seizures or motor disturbances such as limb twitching or paralysis. The mortality rate associated with rebleeding is extremely high, which is why early intervention—such as surgical clipping or endovascular coiling—is typically recommended to secure the aneurysm and prevent further bleeding.

2. Cerebral Vasospasm: A Delayed but Dangerous Threat

Another major complication is cerebral vasospasm, which typically occurs between 3 to 14 days after the initial hemorrhage. Blood that has leaked into the subarachnoid space irritates the surrounding blood vessels, causing them to constrict abnormally. This narrowing reduces blood flow to vital areas of the brain, potentially leading to delayed cerebral ischemia or even stroke. Symptoms may include confusion, weakness on one side of the body, speech difficulties, or decreased levels of alertness. To mitigate this risk, patients are often treated with medications like nimodipine and monitored closely using transcranial Doppler ultrasound or CT angiography.

Preventing and Managing Vasospasm

Medical teams frequently employ a strategy known as "Triple H Therapy"—hypertension, hypervolemia, and hemodilution—to maintain adequate cerebral perfusion during the high-risk period. However, recent guidelines emphasize careful fluid management and induced hypertension only when ischemia is detected, to avoid complications such as pulmonary edema or heart strain.

3. Hydrocephalus: A Common Long-Term Challenge

Hydrocephalus is another frequent consequence of subarachnoid hemorrhage. Blood clots can obstruct the normal flow of cerebrospinal fluid (CSF) through the ventricles and subarachnoid space, leading to an accumulation of fluid in the brain. This acute form of hydrocephalus often presents with headaches, nausea, vomiting, and altered mental status. In many cases, temporary drainage via an external ventricular drain (EVD) is required to relieve pressure.

Chronic Hydrocephalus and Normal Pressure Hydrocephalus (NPH)

Even more insidiously, some patients develop what's known as normal pressure hydrocephalus (NPH) weeks after the initial event. This occurs when breakdown products from the blood interfere with CSF absorption at the arachnoid granulations. Over time, this leads to ventricular enlargement despite normal pressure readings on lumbar puncture. Symptoms include gait instability, cognitive decline, and urinary incontinence—the classic "wet, wobbly, and wacky" triad. For these patients, long-term treatment may involve the placement of a permanent shunt system to divert excess fluid.

In summary, while subarachnoid hemorrhage itself is a medical emergency, the complications that follow—rebleeding, cerebral vasospasm, and hydrocephalus—pose significant threats to recovery and survival. Advances in neurocritical care, imaging, and surgical techniques have improved outcomes, but early detection and aggressive management remain key to minimizing disability and enhancing quality of life for survivors.