The hallmark of aSAH in a patient who is awake is the complaint the worst headache of my life, which is described by 80% of patients who can give a history.82 This headache is characterized as being extremely sudden and immediately reaching maximal intensity (thun- derclap headache). A warning or sentinel headache that precedes the aSAH-associated ictus is also reported by 10% to 43% of patients.83,84 This sentinel headache increases the odds of early rebleeding 10-fold.85 Most intracranial aneu- rysms remain asymptomatic until they rupture. aSAH can occur during physical exertion or stress.86 Nevertheless, in a review of 513 patients with aSAH, the highest incidence of rupture occurred while patients were engaged in their daily routines, in the absence of strenuous physical activity.87 The onset of headache may be associated with 1 additional signs and symptoms, including nausea and/or vomiting, stiff neck, photophobia, brief loss of consciousness, or focal neurolog- ical deficits (including cranial nerve palsies). In a retrospec- tive study of 109 patients with proven aSAH, headache was present in 74%, nausea or vomiting in 77%, loss of con- sciousness in 53%, and nuchal rigidity in 35%.88 As many as 12% of patients die before receiving medical attention. Despite the classic presentation of aSAH, individual find- ings occur inconsistently, and because the type of headache from aSAH is sufficiently variable, misdiagnosis or delayed diagnosis is common. 