Spontaneous subarachnoid hemorrhage (SAH) is a can’t miss diagnosis for patients presenting to the emergency department with a headache. The diagnosis is associated with a 30% mortality at 30 days, and approximately 30% of survivors may have long-term neurocognitive deficits (Rincon et al., 2013). The majority of spontaneous SAH are secondary to a ruptured arterial aneurysm (80%) while non-aneurysmal SAH are often due to low pressure venous bleeds, arteriovenous malformations, and other more rare causes. This post will recap the existing literature on the diagnosis of aSAH and will focus on breaking down a recently published paper by Vincent, et al which may inform our future practice.