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

Approach to Headache Assessment

A systematic approach to headache assessment begins with identifying whether the headache is primary (migraine, tension-type, cluster) or secondary (caused by underlying pathology), using the International Classification of Headache Disorders (ICHD-3) criteria as the diagnostic framework. 1, 2

Definition

• Headache is pain or discomfort in the head or face region that can be classified as primary (no underlying structural cause) or secondary (caused by another condition) 3, 4
• Approximately 50% of adults worldwide are affected by headache disorders 3
• Migraine is the second most prevalent neurological disorder globally and causes more disability than all other neurological disorders combined 1, 5

Classification

Primary Headaches 1, 2, 4

Migraine without aura:

• Requires ≥5 attacks lasting 4-72 hours 1, 2
• At least 2 of: unilateral location, pulsating quality, moderate-to-severe intensity, aggravation by routine activity 1, 2
• At least 1 of: nausea/vomiting, photophobia and phonophobia 1, 2
• Note: ~40% report bilateral pain, so unilateral location is not mandatory 1

Migraine with aura:

• Requires ≥2 attacks with fully reversible visual, sensory, speech, motor, brainstem, or retinal symptoms 2
• Symptoms spread gradually over ≥5 minutes and last 5-60 minutes 2
• Headache follows within 60 minutes of aura 2

Chronic migraine:

• Headache ≥15 days per month for >3 months 1
• On ≥8 days/month, headache has migraine features 1

Tension-type headache:

• At least 2 of: pressing/tightening (non-pulsatile) character, mild-to-moderate intensity, bilateral location, no aggravation with routine activity 1
• No nausea/vomiting (anorexia acceptable) 1
• No photophobia AND phonophobia (may have one or the other) 1

Cluster headache:

• Five attacks with frequency of 1-8 attacks per day 1
• Severe unilateral orbital/supraorbital/temporal pain lasting 15-180 minutes 1
• At least 1 ipsilateral autonomic feature: lacrimation, nasal congestion, rhinorrhea, facial sweating, ptosis, miosis, eyelid edema 1

Secondary Headaches 3, 6, 4

• Headaches caused by infection, vascular disease, intracranial pathology, trauma, medication overuse, or systemic illness 3, 6

Differential Diagnosis

Primary Headache Differentials 1, 3, 4

• Migraine vs. tension-type headache vs. cluster headache (distinguished by frequency, location, duration, triggers, presence of aura) 6, 4
• Spontaneous intracranial hypotension (orthostatic headache) 1
• Postural tachycardia syndrome (PoTS) 1
• Orthostatic hypotension 1
• Cervicogenic headache 1

Secondary Headache Differentials 3, 7, 6

• Subarachnoid hemorrhage/intracranial hemorrhage 1, 3
• Meningitis/encephalitis 7, 6
• Brain tumor/mass lesion 7, 6
• Giant cell arteritis (temporal arteritis) 3, 6
• Idiopathic intracranial hypertension 7, 6
• Medication overuse headache 1, 8
• Cerebral venous thrombosis 6
• Acute angle-closure glaucoma 6

History Taking

Character of Headache 1, 3, 8

Timing and Pattern:

• Frequency: How often do headaches occur? 1
• Duration: How long does each episode last? 1, 2
• Time of day: When do headaches typically occur? 1
• Onset: Sudden (thunderclap) vs. gradual 1, 3
• Pattern: Episodic vs. chronic vs. progressive 8, 7

Pain Characteristics:

• Location: Unilateral vs. bilateral, frontal vs. temporal vs. occipital 1
• Quality: Pulsating vs. pressing/tightening vs. stabbing 1
• Intensity: Mild, moderate, or severe (use 0-10 verbal rating scale) 1
• Aggravating factors: Routine physical activity, movement, posture 1
• Relieving factors: Rest, lying flat, darkness 1

Associated Symptoms:

• Nausea and/or vomiting 1, 2
• Photophobia and phonophobia 1, 2
• Aura symptoms (visual, sensory, speech, motor) 2
• Autonomic features (lacrimation, nasal congestion, ptosis, miosis) 1
• Neurological symptoms 3, 7

Prodromal Symptoms:

• Depressed mood, yawning, fatigue, food cravings 1

Red Flags (SNNOOP10 Screening) 3, 8, 7

Critical red flags requiring urgent evaluation:

• Sudden onset of worst headache in patient's life (thunderclap) 1, 3, 7
• New onset after age 50 years 3, 7
• Neurologic signs or symptoms (focal deficits, altered consciousness, confusion, personality changes) 1, 3, 7
• Onset with exertion, Valsalva, or sexual activity 3
• Orthostatic component (worse upright, better lying flat) 1
• Papilledema or visual changes 3, 7
• Progressive headache or increased frequency/severity 1, 3, 7
• Precipitated by trauma 3, 7
• Positional headache (worse with exercise) 3
• Pregnancy or postpartum 8
• Painful eye with autonomic features 8
• Postinfectious (fever, neck stiffness, rash) 7
• Pathology of immune system (HIV, immunosuppression) 3, 7
• Prior cancer history 8

Risk Factors 1, 8

• Family history of migraine 1
• Female sex (migraine prevalence ~15% general population) 1
• Connective tissue disorders or joint hypermobility 1
• Medication overuse (≥10 days/month for triptans, ≥15 days/month for simple analgesics) 1, 8
• Depression, anxiety, substance abuse 8
• Chronic musculoskeletal pain syndromes 8
• Sleep disorders 8

Additional History Elements 1, 8

• Menstrual relationship in women 1
• Medication history including over-the-counter analgesics 8
• Substance use (opiates, barbiturates, benzodiazepines) 8
• Previous treatments and responses 1, 8
• Impact on daily activities, work, school 8
• Triggers: stress, foods, alcohol, sleep deprivation, weather changes 8

Physical Examination

Focused Neurological Examination 3, 8, 7

Vital Signs:

• Blood pressure (orthostatic measurements if indicated) 1
• Heart rate (standing test for PoTS if suspected) 1
• Temperature (fever suggests infection) 7

General Inspection:

• Level of consciousness and mental status 7
• Signs of distress or pain 3

Head and Neck Examination:

• Palpation of temporal arteries (tenderness, decreased pulse suggests giant cell arteritis) 3
• Neck stiffness/meningismus (suggests meningitis or subarachnoid hemorrhage) 3, 7
• Cervical range of motion and myofascial tenderness (cervicogenic headache) 1
• Sinus tenderness 3
• Temporomandibular joint examination 3

Cranial Nerve Examination:

• Visual acuity and visual fields 7
• Pupillary responses (asymmetry suggests structural lesion) 7
• Extraocular movements 7
• Facial sensation and strength 7
• Fundoscopic examination for papilledema 3, 7

Motor and Sensory Examination:

• Focal weakness or sensory deficits 3, 7
• Coordination and gait 7
• Deep tendon reflexes and plantar responses 7

Cardiovascular Examination:

• If autonomic dysfunction suspected 1

Investigations

When Neuroimaging is NOT Indicated 1, 7

• Migraine with typical features and normal neurological examination 1
• Patient not at higher risk than general population for intracranial pathology 1
• Results would not change management 1

When Neuroimaging IS Indicated 1, 3, 7

Indications for urgent imaging:

• Any red flag signs or symptoms present 1, 3, 7
• Rapidly increasing headache frequency 1
• History of lack of coordination 1
• Focal neurologic signs or symptoms 1, 3
• Headache awakening patient from sleep 1
• Abrupt onset of severe headache 1, 3
• Marked change in headache pattern 1, 7
• Persistent headache following head trauma 1
• Abnormal neurological examination 3, 7

Imaging Modality Selection 3, 7

Non-contrast CT head (first-line for suspected hemorrhage):

• Suspected subarachnoid hemorrhage or intracranial hemorrhage 3, 7
• Acute trauma 7
• Rapid availability and lower cost 7

MRI brain (preferred for most other indications):

• More detailed imaging, necessary for posterior fossa 7
• Suspected tumor, infection, vascular malformation 7
• Spontaneous intracranial hypotension 1
• When CT is normal but clinical suspicion remains high 7

Expected findings:

• Primary headaches: Normal imaging 3, 7
• Subarachnoid hemorrhage: Hyperdensity in subarachnoid spaces on CT 3
• Tumor: Mass effect, edema, enhancement 6
• Spontaneous intracranial hypotension: Diffuse pachymeningeal enhancement, brain sagging 1

Lumbar Puncture 3, 7

Indications:

• Suspected meningitis/encephalitis (fever, neck stiffness, altered mental status) 7
• Suspected subarachnoid hemorrhage with normal CT (perform after normal CT) 3, 7
• Suspected idiopathic intracranial hypertension (measure opening pressure) 7
• Suspected spontaneous intracranial hypotension (low opening pressure) 1

Expected CSF findings:

• Bacterial meningitis: Elevated WBC (neutrophils), elevated protein, low glucose 7
• Viral meningitis: Elevated WBC (lymphocytes), normal/elevated protein, normal glucose 7
• Subarachnoid hemorrhage: RBCs, xanthochromia (if >12 hours from onset) 7

Laboratory Tests 8, 6

When indicated by clinical suspicion:

• ESR/CRP (giant cell arteritis if age >50 with new headache) 3, 6
• Complete blood count (infection, anemia) 6
• Metabolic panel (electrolyte disturbances) 6
• Thyroid function tests (if symptoms suggest thyroid disorder) 8

Other Tests 1, 8

Electroencephalography (EEG):

• NOT useful in routine headache evaluation 1
• Consider only if: seizure disorder suspected, atypical migrainous aura, episodic loss of consciousness 1

Headache diary/calendar:

• Essential for documenting frequency, severity, duration, triggers, medication use 1, 2, 8
• Should be completed on symptomatic days 1

Empiric Treatment

Acute Treatment of Migraine 2

First-line (mild-to-moderate attacks):

• NSAIDs: Ibuprofen, aspirin, diclofenac potassium, or naproxen 2
• Acetaminophen (paracetamol) 2

Second-line (moderate-to-severe attacks or inadequate response to NSAIDs):

• Triptans (sumatriptan, rizatriptan, zolmitriptan, others) 2
• Combination: Triptan + fast-acting NSAID if triptan alone insufficient 2

Antiemetics:

• For nausea/vomiting: Metoclopramide or domperidone (age ≥12 years) 5

Special populations:

• Pregnant/breastfeeding women: Acetaminophen only; avoid preventive therapy if possible 2
• Children: Bed rest alone may suffice for short attacks; ibuprofen first-line if medication needed 5
• Adolescents (12-17 years): NSAIDs or triptans (nasal spray formulations of sumatriptan/zolmitriptan most effective) 5
• Older adults: Monitor cardiovascular risk carefully with triptans 2

Preventive Therapy Indications 2

Consider when:

• ≥2 days per month adversely affected despite optimized acute treatment 2
• ≥4 headache attacks per month 2
• ≥8 headache days per month 2
• Contraindication to or failure of acute treatments 2

First-line preventive medications:

• Beta-blockers: Propranolol, timolol, metoprolol 2
• Anticonvulsants: Topiramate, divalproex sodium 2

Medication Overuse Headache Management 1, 8

Suspect when:

• Headache ≥15 days per month 1
• Regular overuse of acute medications (≥10 days/month for triptans, ≥15 days/month for simple analgesics) 1, 8

Treatment:

• Abrupt withdrawal preferred (except opioids, barbiturates, benzodiazepines which require slow taper) 1, 8
• Patient education about expected worsening before improvement 1
• Start preventive therapy in parallel with withdrawal 1
• Opioid/barbiturate/benzodiazepine overuse may require inpatient management 8

Indications to Refer

Refer to Specialist (Neurology/Headache Specialist) 1, 7

Approximately 90% of migraine patients should be managed in primary care; refer the remaining 10% when: 1

• Diagnostically challenging cases (atypical features, unclear diagnosis) 1, 7
• Difficult to treat (failure of multiple first-line therapies) 1
• Complicated by significant comorbidities 1
• Red flags present with concerning imaging or examination findings 7
• Suspected secondary headache requiring subspecialty expertise 7
• Medication overuse involving opioids, barbiturates, or benzodiazepines 8
• Progressive neurological deficits 7
• Need for multidisciplinary care 1

Urgent/Emergency Referral 3, 7

• Thunderclap headache (subarachnoid hemorrhage until proven otherwise) 1, 3
• Headache with fever, neck stiffness, altered mental status (meningitis/encephalitis) 7
• Headache with focal neurological deficits 3, 7
• Headache with papilledema 3, 7
• New severe headache in immunocompromised patient 3, 7
• Headache after significant head trauma 3, 7

Critical Pitfalls

Diagnostic Pitfalls 1, 3, 8

• Assuming unilateral pain is required for migraine diagnosis – ~40% of migraine patients report bilateral pain 1
• Over-relying on neuroimaging – Most primary headaches have normal imaging; image only when red flags present or patient at higher risk than general population 1, 3
• Missing medication overuse headache – Always obtain detailed medication history including over-the-counter analgesics and substances obtained from others 8
• Failing to recognize orthostatic headache – Spontaneous intracranial hypotension can present as "end of day" headache or follow thunderclap headache; requires specific positional history 1
• Dismissing headache in older adults – New headache after age 50 is a red flag requiring evaluation for giant cell arteritis and other secondary causes 3, 7
• Inadequate red flag screening – Use systematic approach (SNNOOP10) to avoid missing dangerous secondary headaches 8

Treatment Pitfalls 1, 2, 8

• Under-treating migraine – Only 2-14% of eligible patients receive preventive therapy; consider preventive therapy early when indicated 1, 2
• Inadequate acute treatment dosing – Ensure adequate doses of NSAIDs or triptans; some patients need higher doses, others need lower doses to improve adherence 1
• Not addressing medication overuse – Failure to identify and treat medication overuse headache leads to chronic intractable headaches 1, 8
• Premature conclusion of treatment failure – Review diagnosis, dosing, and adherence before concluding treatment has failed 1
• Ignoring comorbidities – Depression, anxiety, substance abuse, and chronic pain syndromes impair treatment effectiveness and must be addressed 8
• Lack of patient education – Patients with medication overuse headache need education about expected worsening before improvement during withdrawal 1

Follow-up Pitfalls 1, 2, 8

• Inadequate monitoring – Evaluate treatment response 2-3 months after initiation or change, then every 6-12 months 1, 2
• Not using headache diaries – Headache calendars are essential for tracking frequency, severity, and medication use 1, 2
• Failing to use validated assessment tools – mTOQ-4, HURT questionnaire, and HIT-6 provide objective measures of treatment effectiveness 1, 2
• Irregular follow-up – Regular scheduled follow-up is essential to monitor progress and prevent chronic transformation 8

Special Population Pitfalls 2, 5

• Using inappropriate medications in pregnancy – Only acetaminophen is safe for acute treatment; avoid preventive therapy if possible 2
• Ignoring cardiovascular risk in elderly – Triptans require careful cardiovascular risk assessment in older adults 2
• Applying adult criteria to children – Pediatric migraine has shorter duration (2-72 hours vs. 4-72 hours), more bilateral presentation, and prominent GI symptoms 5
• Misinterpreting high placebo response in children – Therapeutic gain appears low in pediatric trials; bed rest alone may suffice for short attacks 5