Is Subarachnoid Hemorrhage a Stroke?
Yes, subarachnoid hemorrhage (SAH) is definitively classified as a type of stroke—specifically, a hemorrhagic stroke that accounts for approximately 5% of all strokes. 1, 2, 3
Classification Within Stroke Subtypes
SAH represents the third most common subtype of stroke after ischemic stroke and intracerebral hemorrhage (ICH). 4 The American Heart Association's Stroke Council explicitly categorizes SAH as a hemorrhagic stroke, distinguishing it from both ischemic stroke and other forms of intracranial hemorrhage. 5
Key Distinguishing Features from Other Strokes
While SAH is a stroke, it has several unique characteristics that differentiate it from ischemic and other hemorrhagic strokes:
Age of onset: SAH affects a younger population (mean age in the mid-50s) compared to ischemic stroke, resulting in more potential years of life lost and greater societal burden. 1, 4
Clinical presentation: The hallmark sudden-onset "thunderclap" headache reaching maximal intensity within 1 hour is sufficiently distinct from typical ischemic or ICH presentations, though misdiagnosis still occurs in up to 12% of cases. 5, 1
Mortality profile: SAH carries the highest early mortality among stroke types, with approximately 12% dying before reaching medical attention and 30-day mortality rates of 45%. 1, 4
Classification in Research and Clinical Practice
In stroke genetics research and clinical trials, SAH is explicitly separated from ischemic stroke and ICH, requiring distinct data collection structures for location, severity grading (Hunt-Hess or WFNS scales), and imaging characteristics. 5 This separation reflects fundamental differences in pathophysiology, treatment approaches, and outcomes, even though all three conditions fall under the umbrella term "stroke."
Clinical Implications of This Classification
The classification of SAH as a stroke has important practical implications:
Stroke center protocols: SAH patients should be managed in specialized stroke centers with neurosurgical capabilities, not general stroke units designed primarily for ischemic stroke. 4
Treatment exclusions: The presence of SAH is an absolute contraindication to thrombolytic therapy (tPA) used for ischemic stroke, making accurate differentiation critical. 5
Epidemiological reporting: SAH is included in stroke statistics and public health surveillance, contributing to overall stroke burden calculations. 1, 3