What is the approach to assessing headaches, including definition, differential diagnosis, history, physical examination, investigations, empiric treatment, and indications for referral?

Approach to Assessment of Headaches

Definition

Headache is pain or discomfort in the head or face region, classified as primary (migraine, tension-type, cluster) or secondary (underlying pathology causing the headache). 1

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Differential Diagnosis

Primary Headache Disorders

• Migraine without aura: Recurrent moderate-to-severe unilateral, pulsating headache lasting 4-72 hours with nausea/vomiting, photophobia, and phonophobia; worsens with routine activity 1
• Migraine with aura: Above features plus recurrent short-lasting visual/hemisensory disturbances (lasting <60 minutes) preceding or accompanying headache 1
• Chronic migraine: ≥15 headache days/month for >3 months, with ≥8 days meeting migraine criteria 1
• Tension-type headache: Bilateral, mild-to-moderate pressing/tightening quality; lacks migraine features; not aggravated by routine activity 1
• Cluster headache: Strictly unilateral severe headache lasting 15-180 minutes with ipsilateral autonomic symptoms (lacrimation, conjunctival injection, nasal congestion, ptosis, miosis) 1
• Medication-overuse headache: ≥15 headache days/month with regular overuse of acute medications (non-opioid analgesics ≥15 days/month or other acute medications ≥10 days/month) for >3 months 1

Secondary Headache Disorders (Life-Threatening)

• Subarachnoid hemorrhage: Thunderclap headache ("worst headache of life"), may have altered taste sensation 1
• Meningitis: Headache with neck stiffness, unexplained fever 1
• Brain tumor/space-occupying lesion: Progressive headache, awakens from sleep, worsens with Valsalva/cough 1
• Giant cell arteritis: New-onset headache in patients >50 years with scalp tenderness, jaw claudication 1
• Stroke/TIA: Atypical aura with focal neurological symptoms 1
• Increased intracranial pressure: Headache worsening with coughing, sneezing, exercise 1
• Spontaneous intracranial hypotension: Orthostatic headache (absent/mild on waking, onset within 2 hours of upright posture, >50% improvement within 2 hours of lying flat) 1

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History

Character of Pain

• Location: Unilateral (migraine, cluster) vs bilateral (tension-type) 1
• Quality: Pulsating (migraine) vs pressing/tightening (tension-type) vs severe unilateral (cluster) 1
• Severity: Moderate-to-severe (migraine, cluster) vs mild-to-moderate (tension-type) 1
• Duration: Migraine 4-72 hours; cluster 15-180 minutes; tension-type variable 1
• Frequency: Episodic vs chronic (≥15 days/month) 1
• Age at onset: Migraine typically begins at/around puberty 1

Aggravating and Relieving Factors

• Aggravating: Routine activity worsens migraine but not tension-type; Valsalva/cough suggests secondary causes 1
• Relieving: Lying flat improves orthostatic headache 1

Accompanying Symptoms

• Migraine-associated: Nausea/vomiting, photophobia, phonophobia 1
• Cluster-associated: Autonomic symptoms (lacrimation, conjunctival injection, nasal congestion) 1
• Aura symptoms: Visual/hemisensory disturbances lasting <60 minutes 1

Medication History

• Document: Acute and preventive medication history for medication-overuse headache 1

Red Flags (Require Urgent Investigation)

• Thunderclap headache (subarachnoid hemorrhage) 1
• New-onset headache after age 50 (giant cell arteritis, tumor) 1
• Progressive worsening headache (tumor, increased intracranial pressure) 1
• Atypical aura (stroke/TIA) 1
• Recent head/neck trauma (subdural hematoma) 1, 2
• Headache awakening patient from sleep (tumor, increased intracranial pressure) 1
• Headache brought on by Valsalva, cough, or exertion (increased intracranial pressure, Chiari malformation) 1, 2
• Focal neurological symptoms/signs (stroke, tumor) 1
• Unexplained fever (meningitis, encephalitis) 1
• Neck stiffness or limited neck flexion (meningitis, subarachnoid hemorrhage) 1
• Altered consciousness, memory, or personality (encephalitis, tumor) 1
• Witnessed loss of consciousness (seizure, syncope) 1

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Physical Examination (Focused)

Neurological Examination

• Complete neurological examination to detect focal deficits suggesting secondary causes 2
• Fundoscopy for papilledema (increased intracranial pressure) 2
• Neck examination for stiffness/limited flexion (meningitis, subarachnoid hemorrhage) 1

Vascular Examination

• Temporal artery palpation for tenderness, reduced pulse (giant cell arteritis in patients >50 years) 1

Vital Signs

• Blood pressure monitoring to detect hypertension (secondary headache) 2

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Investigations

Screening Tools

• ID-Migraine questionnaire (3-item): Sensitivity 0.81, specificity 0.75, positive predictive value 0.93 1
• Migraine Screen Questionnaire (5-item): Sensitivity 0.93, specificity 0.81, positive predictive value 0.83 1
• Headache diary: Document frequency, duration, character, triggers, accompanying symptoms, medication use 1

Neuroimaging

• MRI brain with and without contrast: Preferred modality for subacute presentations or suspected tumor/inflammatory process; higher resolution, no ionizing radiation 1
• Non-contrast CT head: If presenting <6 hours from acute severe headache onset (subarachnoid hemorrhage); sensitivity 95% on day 0,74% on day 3,50% at 1 week 1
• CT head: Acute trauma or abrupt-onset headache 1

Laboratory Tests

• ESR/CRP: If temporal arteritis suspected (patients >50 years with new-onset headache); note ESR can be normal in 10-36% of giant cell arteritis cases 1, 3
• Morning TSH and free T4: If cold intolerance, lightheadedness present (hypothyroidism) 1
• Thyroid peroxidase (TPO) antibodies: If biochemical hypothyroidism confirmed 1

Other Investigations

• Dental panoramic radiographs: If dental pathology or sinusitis suspected 1
• Lumbar puncture with CSF analysis: If subarachnoid hemorrhage suspected with negative CT (xanthochromia detection: 100% at 12 hours to 1 week, >70% at 3 weeks) 3

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Empiric Treatment

Acute Treatment for Migraine

• NSAIDs or acetaminophen: First-line for mild-to-moderate migraine attacks 1
• Triptans or ergot derivatives: For moderate-to-severe migraine attacks or when NSAIDs fail 1
• Antiemetics: For nausea/vomiting 1

Acute Treatment for Cluster Headache

• High-flow oxygen (100% at 12-15 L/min): First-line acute treatment 1
• Subcutaneous or intranasal triptans: Alternative acute treatment 1

Preventive Treatment

• Consider prophylactic treatment when patients are adversely affected on ≥2 days per month despite optimized acute treatment 4

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Indications to Refer

Emergency Admission (Immediate)

• Patient unable to self-care without help 1
• Any red flag present (thunderclap headache, focal neurological signs, altered consciousness, fever with neck stiffness) 1

Urgent Referral to Neurology (Within 48 Hours)

• Suspected spontaneous intracranial hypotension 1
• Patient unable to self-care but has help 1

Urgent Referral to Specialist/Tertiary Center (Within 1 Month)

• Diagnosis in doubt 1
• First-line treatments fail 1
• Rapid clinical deterioration 1
• Serious complications 1

Routine Referral to Neurology (2-4 Weeks)

• Suspected primary headache disorder 1
• Diagnosis uncertain 1
• First-line treatments fail 1

Referral to Rheumatology

• Suspected giant cell arteritis 1

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Critical Pitfalls

Diagnostic Pitfalls

• Missing subarachnoid hemorrhage: CT sensitivity decreases rapidly after day 0 (95% on day 0,50% at 1 week); always perform lumbar puncture if CT negative and clinical suspicion high 1, 3
• Normal ESR does not exclude giant cell arteritis: ESR can be normal in 10-36% of cases; maintain high clinical suspicion in patients >50 years with new-onset headache and temporal artery tenderness 1, 3
• Misdiagnosing sentinel headache from subarachnoid hemorrhage: Headaches from SAH are often misdiagnosed; always consider SAH in "first or worst" headache presentations 3
• Overlooking medication-overuse headache: Regular overuse of acute medications (≥15 days/month for NSAIDs, ≥10 days/month for triptans) for >3 months causes medication-overuse headache, which requires different management 1
• Treating secondary headache as primary: Always exclude secondary causes before diagnosing primary headache disorder; red flags mandate investigation 1, 2

Treatment Pitfalls

• Cardiovascular risks with triptans: Triptans can cause coronary vasospasm; contraindicated in patients with uncontrolled hypertension, coronary artery disease, or cardiovascular risk factors 5
• NSAID cardiovascular and gastrointestinal risks: NSAIDs increase risk of serious cardiovascular thrombotic events, myocardial infarction, stroke, and gastrointestinal ulceration/bleeding; use lowest effective dose for shortest duration 5
• Serotonin syndrome with triptans and SSRIs/SNRIs: Combined use can cause life-threatening serotonin syndrome; monitor for mental status changes, autonomic instability, neuromuscular aberrations 5
• Delayed benefit of preventive medications: Benefits may take several weeks to become apparent; encourage adherence and set realistic expectations 4
• Failure to discontinue preventive medication: Consider discontinuing after 3-6 months of stability to determine if prophylaxis is still needed 4

Management Pitfalls

• Inadequate follow-up: Schedule regular follow-up visits to monitor frequency, severity, and response to treatment using standardized tools like HIT-6 4
• Ignoring comorbidities: Consider comorbid conditions (depression, anxiety, cardiovascular disease) when selecting prophylactic medications 4
• Underutilizing headache diaries: Headache diaries reduce recall bias, increase diagnostic accuracy, and help identify triggers and monitor treatment effectiveness 1, 4