What pertinent negatives should be assessed in a patient presenting with migraine?

Pertinent Negatives in Migraine Assessment

The most critical pertinent negatives when evaluating a patient with suspected migraine are the absence of red flag features that would indicate a secondary headache disorder requiring urgent investigation, specifically: no thunderclap onset, no focal neurological deficits on examination, no fever, no neck stiffness, no impaired consciousness or memory, no head trauma, and no features suggesting increased intracranial pressure. 1

Red Flags That Must Be Absent

When assessing for migraine, the following features should be explicitly documented as absent to support a primary headache diagnosis rather than a dangerous secondary cause:

Historical Red Flags to Rule Out

• No thunderclap headache (sudden, severe onset reaching maximum intensity within seconds to minutes, which suggests subarachnoid hemorrhage) 1
• No recent head trauma (which could indicate subdural hematoma) 1
• No progressive worsening pattern (which suggests intracranial space-occupying lesion) 1
• No headache aggravated by Valsalva maneuvers, coughing, sneezing, or exercise (suggesting intracranial hypertension or space-occupying lesion) 1, 2
• No positional component (headaches worsened by specific postures suggest intracranial hypertension or hypotension) 1
• No new onset after age 50 (which increases suspicion for secondary causes including temporal arteritis) 1
• No associated weight loss or personality changes (suggesting systemic disease or intracranial pathology) 1

Physical Examination Red Flags to Rule Out

• No fever (which would suggest meningitis or other infectious/inflammatory process) 1
• No neck stiffness (meningitis or subarachnoid hemorrhage) 1
• No focal neurological deficits on examination (persistent deficits suggest stroke, tumor, or other structural lesion) 1
• No papilledema (increased intracranial pressure) 1
• No altered consciousness or impaired memory (suggesting serious intracranial pathology) 1
• Normal neurological examination (the examination should be entirely normal between attacks and during attacks in typical migraine) 1

Distinguishing Migraine Aura from Dangerous Mimics

Features That Should Be Absent to Support Migraine Over TIA/Stroke

• No sudden, simultaneous onset of maximal deficit (migraine aura develops gradually over ≥5 minutes with a characteristic "marching" or spreading quality, whereas TIA symptoms are maximal at onset) 3, 4, 5
• No persistent neurological deficits (migraine aura symptoms must completely resolve, typically within 5-60 minutes; persistent deficits require urgent neuroimaging) 3, 4
• No loss of consciousness (this is never a feature of migraine and demands immediate alternative evaluation) 3
• No negative symptoms in isolation (migraine aura typically includes positive phenomena like scintillations or paresthesias, not just negative symptoms like isolated numbness or weakness) 1, 4

Distinguishing from Other Primary Headache Disorders

Features Absent in Migraine but Present in Cluster Headache

• No strictly unilateral autonomic features (lacrimation, nasal congestion, rhinorrhea, ptosis, miosis, eyelid edema on the same side as pain) 1
• No restlessness or agitation during attacks (migraine patients typically prefer to lie still in a dark, quiet room) 1
• No short duration attacks (cluster headaches last 15-180 minutes; migraine lasts 4-72 hours in adults) 1, 4

Features Absent in Pure Migraine but Present in Medication Overuse Headache

• No regular overuse of acute medications (specifically, not taking non-opioid analgesics ≥15 days/month or triptans/combination medications ≥10 days/month for ≥3 months) 1, 4

Distinguishing Migraine from Vestibular Migraine

When evaluating for typical migraine versus vestibular migraine, document:

• No vertigo or significant dizziness (vestibular migraine presents with moderate-to-severe vestibular symptoms lasting 5 minutes to 72 hours) 1, 3
• No motion intolerance as a primary symptom (this is characteristic of vestibular migraine) 1, 3
• Hearing loss, if present, is not bilateral or related to sound processing difficulty (vestibular migraine may have bilateral auditory complaints related to processing, whereas Ménière's disease has true unilateral hearing loss) 1

Clinical Approach to Documentation

The absence of red flags should be explicitly documented rather than assumed. 1 This serves multiple purposes:

• Supports the diagnosis of primary migraine disorder 1
• Justifies the decision not to pursue neuroimaging (which is only indicated when secondary causes are suspected based on red flags) 1
• Protects against medicolegal concerns by demonstrating thorough evaluation 1
• Prevents unnecessary testing that can reveal clinically insignificant abnormalities (white matter lesions, arachnoid cysts, meningiomas) that alarm patients and lead to further unnecessary investigation 1

A common pitfall is failing to systematically assess and document these pertinent negatives, leading to either missed dangerous secondary headaches or unnecessary neuroimaging in patients with clear primary migraine. 1 The presence of even a single red flag should prompt consideration of neuroimaging (preferably MRI over CT due to higher resolution and no radiation exposure), blood work, or lumbar puncture as clinically indicated. 1