Approach
The key to diagnosis of common forms of migraine is history and exam. Before starting treatment for migraine, it is important to ensure that the patient meets International Classification of Headache Disorders, third edition (ICHD-3) criteria for migraine or probable migraine.[3] A single patient can have more than one headache diagnosis. The diagnosis of migraine does not preclude the diagnosis of another headache disorder if criteria are met.
History
Headache is the key historical feature that supports a diagnosis of migraine. Recurrent headaches that interfere with the patient's ability to function are often migraines but additional migraine features should be sought. Migraine is often unilateral, but, unilateral headache is not required for the diagnosis of migraine.
Patients should be asked about key features of the history: aura symptoms, pulsating/throbbing pain, location of pain, intensity, worsening with routine physical activity, photophobia, phonophobia, and nausea or vomiting.[3] Use of a headache diary or calendar may assist with this.[39] Not every feature is required to meet criteria for migraine. Headaches should last between 4 and 72 hours. See Criteria.
Diagnostic tests
Diagnostic testing for people with headache is primarily to exclude concerning or problematic causes for headache, as there is no specific test revealing the causes of pain in the head. In many cases where the history is compatible with a diagnosis of migraine and the neurologic exam is normal, no testing is necessary.[39]
Features that should increase suspicion of a dangerous underlying headache or migraine mimic can be summarized using the "SNOOP4" mnemonic:
Systemic symptoms: fever, weight loss
Neurologic symptoms or abnormal signs: confusion, impaired alertness or consciousness
Onset: sudden, abrupt, or split-second
Older: new-onset and progressive headache, especially in patients aged >50 years
4 "P"s
Pattern change (increased frequency)
Papilledema
Precipitating factors (valsalva, etc)
Positional aggravation[40]
Imaging
Neuroimaging is not needed for patients with headaches consistent with migraine who have a normal neurologic examination, with no atypical features or red flags present.[39][41][42][43][44]
Magnetic resonance imaging (MRI) imaging (with contrast) is the recommended test for patients with concerning headaches in nearly all situations. Computed tomography (CT) brain (without contrast) is recommended for the emergency evaluation of acute headache to evaluate for intracranial hemorrhage. In all other situations MRI is the preferred test, unless contraindicated.[42]
Vascular imaging (CT, MRI, or conventional angiography) may be appropriate for patients where there is concern for unruptured aneurysm, arterial dissection, or venous occlusion.[42]
Laboratory testing and serologies
Routine laboratory testing may reveal thyroid abnormalities, anemia, or electrolyte abnormalities contributing to a headache disorder, and may be appropriate based on the patient's history and prior medical care. Erythrocyte sedimentation rate and C-reactive protein are appropriate to exclude meningitis, and to evaluate for vasculitis and giant cell arteritis in older patients.[45]
Lumbar puncture
Lumbar puncture (LP) is generally recommended for all patients undergoing urgent evaluation for abrupt-onset headache, especially if CT imaging is negative. CT imaging may miss up to 6% of patients with a subarachnoid hemorrhage.[46]
Patients with headache and fever or altered cognition require imaging and LP to evaluate for meningitis or encephalitis.
Patients with papilledema should undergo LP after imaging for measurement of cerebrospinal fluid pressure.
Consider LP for inpatients with frequent headaches that are unresponsive to standard treatments.
Diagnostic lumbar puncture in adults: animated demonstrationHow to perform a diagnostic lumbar puncture in adults. Includes a discussion of patient positioning, choice of needle, and measurement of opening and closing pressure.
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