Migraine headaches are common and manifest in myriad ways, but there are some features that are fairly typical and when present together are suggestive of migraine: pulsatile quality, duration of 4–72 hours, unilateral location, associated nausea/vomiting, and disabling severity. Migraines, however, rarely start suddenly. A patient with headache should always be asked about the onset of pain: if the pain started suddenly and/or is unusual to the patient, then even if there is a history of migraines alternative diagnoses (particularly SAH) should be ruled out.