Rationale and evidence
Rationale
Headache is a common disorder with many potential causes. The primary headache disorders, which include migraine and tension headaches, account for the majority of headaches. Secondary headaches, which are those with underlying pathology (e.g., tumour, aneurysm, or giant cell arteritis) are far less common. Most patients presenting with headache will not have a serious underlying condition. Neuroimaging is not usually warranted for patients with recurrent migraine or tension headaches and a normal neurological examination.
The likelihood of significant intracranial lesions on CT or MRI in this group is less than 1% and can be as low as 0.2%. Headache worsened by Valsalva manoeuvre, headache causing awakening from sleep, new headache in the older population, or progressively worsening headache may indicate a higher likelihood of finding significant abnormalities on CT or MRI as does the presence of abnormal neurological signs on examination.
Evdience
Health Quality Ontario. Neuroimaging for the Evaluation of Chronic Headaches: An Evidence-Based Analysis. Ont Health Technol Assess Ser 2010; 10 (26): 1–57.
Frishberg BM, Rosenberg JH, Matchar DB, et al. Evidence based guidelines in the primary care setting: neuroimaging in patients with non-acute headache.