Investigations
1st investigations to order
clinical diagnosis
Test
Diagnosis is based on history and physical exam. Testing is not used to 'rule in' a diagnosis of migraine, but rather to 'rule out' plausible alternative diagnoses that are suggested by the patient's presentation.[3][39]
Imaging is not needed for patients with headaches consistent with migraine who have a normal neurological examination, with no atypical features or red flags present.[41][42][43][44] Studies have demonstrated very few significant structural abnormalities on neuroimaging in patients presenting with migraine.[42]
Patients with a significant likelihood of structural disease requiring immediate attention will be detected by validated clinical screening tools. Incidental findings found on imaging may lead to additional medical procedures and expense that do not improve patient outcomes.[43]
Result
fulfils International Classification of Headache Disorders (ICHD)-3 criteria for migraine
Investigations to consider
erythrocyte sedimentation rate (ESR)
Test
ESR is raised in temporal arteritis, and biopsy of temporal artery shows typical inflammatory infiltrate.[45] Likely to be elevated in meningitis.
Result
normal in migraine
c-reactive protein (CRP)
Test
CRP is elevated in temporal arteritis, and biopsy shows typical inflammatory infiltrate.
Elevated in meningitis.
Result
normal in migraine
lumbar puncture (LP)
Test
LP may be abnormal in patients with headache caused by subarachnoid haemorrhage, meningitis, and either low or high cerebrospinal fluid pressure.
How to perform a diagnostic lumbar puncture in adults. Includes a discussion of patient positioning, choice of needle, and measurement of opening and closing pressure.
Result
normal in migraine
cerebrospinal fluid (CSF) culture
Test
If headache is caused by systemic or central nervous system infection, culture and microscopy of CSF and samples from other potential sites of infection may identify the infecting micro-organism.
Result
normal in migraine
MRI brain
Test
Neuroimaging is not needed for patients with headaches consistent with migraine who have a normal neurological examination, with no atypical features or red flags present.[39][41][42][43]
MRI (with contrast) is the recommended test for patients with concerning headaches in nearly all situations.
MRI scans with gadolinium may demonstrate pachymeningeal enhancement in low-pressure headache.[42]
Result
normal in migraine; may identify space-occupying lesions or ischaemic lesions
CT head
Test
Neuroimaging is not needed for patients with headaches consistent with migraine who have a normal neurological examination, with no atypical features or red flags present.[41][42][43]
CT brain (without contrast) is recommended for the emergency evaluation of acute headache to evaluate for intracranial haemorrhage. In all other situations MRI is the preferred test, unless contraindicated.[42]
Result
normal in migraine; may identify space-occupying lesions, ischaemic lesions, or subarachnoid haemorrhage
angiography
Test
Angiography (CT, MRI, or conventional) may be considered to investigate thunderclap headache suggesting subarachnoid haemorrhage, arterial dissection, or reversible cerebral vasoconstriction.[42]
Result
normal in migraine
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