Headache subtype diagnosis is only useful if it changes the search for secondary disease, so keep vascular, sleep-related, and intracranial-pressure causes active in the differential.

Exercise headache in older patients should trigger consideration of cardiac cephalalgia; Primary stabbing headache is brief, migratory, and common in migraineurs; Hypnic headache typically wakes older adults from sleep and often responds to caffeine; IIH MRI clues include empty sella, optic nerve sheath distention, and posterior globe flattening; Venous sinus stenting is an emerging option in selected IIH patients