Patients with chronic headaches do not need imaging unless thay have an abnormal neurological exam. The rate of finding abnormalities is 0.2% in migraine, 0% in tension headache – less than the 0.4% In asymptomatic volunteers. Non differentiated “chronic headache” had a rate of 0.5%. Thus in a chronic headache with a normal neurological exam, neuroimaging is not indicated.

Headaches that would benefit from imaging

• Sudden onset of worst headache of life
• Progressively worsening headache
• Headaches in patient with any new neurological exam abnormalities (including papilledema)
• Acute or subacute Headache with symptoms / signs of confusion / altered mental status
• Headache with AM vomiting
• Headache waking patient from sleep
• Headache worse with bending over / Valsava and or brought on by laying down
• Severe headache after head trauma. (Check link for head trauma)

(Source: Report of the quarterly standards Subcommittee of the reference American Academy of Neurology - The utility of Neuroimaging in the evaluation of Headache in patients with normal neurological examinations, Neurology 44(7):119 July 1994)