Common Complications of Subarachnoid Hemorrhage: What You Need to Know
Subarachnoid hemorrhage (SAH) is a life-threatening type of stroke that occurs when bleeding happens in the space between the brain and the surrounding membrane. While immediate medical intervention is crucial, understanding the potential complications that may follow is equally important for patients and caregivers. These complications can significantly affect recovery outcomes and long-term prognosis. Below are the most common post-hemorrhage complications, along with insights into their causes, risk factors, and timelines.
1. Rebleeding: A Critical Early Risk
Rebleeding is one of the most dangerous complications following subarachnoid hemorrhage, particularly within the first few days after the initial event. The mortality rate associated with rebleeding is alarmingly high—reaching up to 50%. The risk is greatest within the first 24 hours, but remains elevated during the entire first month post-bleed.
Studies show that approximately 20% to 30% of patients experience rebleeding within two weeks, increasing to about 30% by the end of the first month. The primary cause is the rupture of an untreated cerebral aneurysm. Certain patient factors increase this risk, including loss of consciousness upon hospital admission, advanced age, female gender, and systolic blood pressure exceeding 170 mmHg. Prompt diagnosis and early surgical or endovascular intervention are essential to prevent this life-threatening recurrence.
2. Cerebral Vasospasm: A Leading Cause of Disability
Cerebral vasospasm is a major contributor to morbidity and mortality in SAH survivors. It affects roughly 20% to 30% of patients and typically leads to delayed cerebral ischemia, which can result in secondary strokes or permanent neurological damage.
Types and Timing of Vasospasm
Vasospasm can be categorized into two types: early-onset and delayed. Early vasospasm may occur immediately after the bleed, lasting only minutes to hours before resolving on its own. However, the more clinically significant form is delayed cerebral vasospasm, which usually begins 3 to 5 days after hemorrhage, peaks between days 5 and 14, and gradually subsides over the next few weeks.
During this critical window, close monitoring using transcranial Doppler ultrasound and neuroimaging is vital. Treatments such as calcium channel blockers (e.g., nimodipine), induced hypertension, and hemodynamic optimization are commonly used to reduce the risk of ischemic injury.
3. Hydrocephalus: Fluid Build-Up in the Brain
Hydrocephalus, or excessive accumulation of cerebrospinal fluid in the brain's ventricles, develops in about 15% to 20% of SAH cases. It is often classified into acute and delayed forms based on onset timing.
Acute Obstructive Hydrocephalus
This type usually appears within the first week after hemorrhage and is caused by blockage of CSF flow due to blood clots. It is considered obstructive and often resolves spontaneously as the blood is gradually absorbed. However, if symptoms like altered mental status, gait instability, or severe headache worsen, emergency interventions such as ventriculostomy or shunt placement may be required.
Delayed Hydrocephalus
More insidious in nature, delayed hydrocephalus typically emerges 2 to 3 weeks post-hemorrhage. Imaging studies like CT scans or MRI will reveal enlarged ventricles. This condition may require long-term management through surgical shunting to relieve intracranial pressure and improve cognitive and motor function.
4. Other Notable Complications
Beyond the major complications, several other systemic issues can arise following SAH, impacting multiple organ systems.
Seizures
Approximately 5% to 10% of patients experience seizures after SAH. The majority—about two-thirds—occur within the first month, though some may manifest up to a year later. Prophylactic antiepileptic drugs are sometimes prescribed, especially in high-risk cases involving cortical involvement or hematoma.
Hyponatremia
Electrolyte imbalances, particularly low sodium levels (hyponatremia), affect 5% to 30% of patients. This is often due to the syndrome of inappropriate antidiuretic hormone secretion (SIADH) or cerebral salt-wasting syndrome (CSWS). Careful fluid and electrolyte management is crucial to avoid complications like confusion, seizures, or coma.
Neurocardiac and Pulmonary Complications
Some patients develop neurogenic stunned myocardium, also known as "brain-heart syndrome," characterized by ECG abnormalities, troponin elevation, and transient cardiac dysfunction. Additionally, acute lung injury or neurogenic pulmonary edema may occur due to sudden sympathetic surge, leading to respiratory distress and requiring intensive care support.
In summary, while subarachnoid hemorrhage itself is a medical emergency, the subsequent complications pose significant challenges to recovery. Awareness, early detection, and proactive management of rebleeding, vasospasm, hydrocephalus, seizures, and systemic disturbances are key to improving survival rates and enhancing quality of life for affected individuals.