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

Approach to Assessment of Headache

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 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

Secondary Headache Disorders (Life-Threatening)

• Subarachnoid hemorrhage: Thunderclap headache ("worst headache of life"), may have altered taste sensation 2
• Meningitis: Headache with neck stiffness, unexplained fever 1, 2
• Brain tumor/space-occupying lesion: Progressive headache, awakens from sleep, worsens with Valsalva/cough 2, 3
• Giant cell arteritis: New-onset headache in patients >50 years with scalp tenderness, jaw claudication 2
• Stroke/TIA: Atypical aura with focal neurological symptoms 1, 2
• Increased intracranial pressure: Headache worsening with coughing, sneezing, exercise 2
• Subdural/epidural hematoma: Post-traumatic headache 3, 4

Other Secondary Causes

• 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
• 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
• Sinusitis: Headache with altered taste, especially post-dental procedures 2
• Hypothyroidism: Cold intolerance, headache, lightheadedness 5

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History

Character (ICHD-3 Criteria Application)

• Age at onset: Migraine typically begins at/around puberty 1
• Duration of episodes: Migraine 4-72 hours; cluster 15-180 minutes; tension-type variable 1
• Frequency: Episodic vs chronic (≥15 days/month) 1
• Pain location: Unilateral (migraine, cluster) vs bilateral (tension-type) 1
• Pain quality: Pulsating (migraine) vs pressing/tightening (tension-type) vs severe unilateral (cluster) 1
• Pain severity: Moderate-to-severe (migraine, cluster) vs mild-to-moderate (tension-type) 1
• Aggravating factors: Routine activity worsens migraine but not tension-type; Valsalva/cough suggests secondary causes 1, 3
• Relieving factors: Lying flat improves orthostatic headache 1
• Accompanying symptoms: Nausea/vomiting, photophobia, phonophobia (migraine); autonomic symptoms (cluster) 1
• Aura symptoms: Visual/hemisensory disturbances lasting <60 minutes 1
• Medication use: Acute and preventive medication history for medication-overuse headache 1

Red Flags (Require Urgent Investigation)

• Thunderclap headache (sudden, severe "worst headache of life") 1, 2, 3
• New-onset headache after age 50 2, 3, 4
• Progressive worsening headache over time 2, 3
• Atypical aura 1
• Recent head/neck trauma 1, 3
• Headache awakening patient from sleep 1, 2
• Headache brought on by Valsalva, cough, or exertion 2, 3
• Focal neurological symptoms/signs 1, 2, 3
• Unexplained fever 1, 2
• Neck stiffness or limited neck flexion 1, 2
• Altered consciousness, memory, or personality 2
• Witnessed loss of consciousness 2
• Systemic signs/symptoms (weight loss, cancer, HIV) 3

Risk Factors

• Family history of migraine: Strong genetic component; prevalence higher in first-degree relatives 1
• Connective tissue disorders/joint hypermobility: Predispose to spontaneous intracranial hypotension 1
• Spinal pathology (osteophytes, disc herniation): Associated with spontaneous intracranial hypotension 1

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Physical Examination (Focused)

Vital Signs

• Blood pressure and heart rate: Supine and after 3 minutes standing to assess orthostatic hypotension (≥20 mmHg systolic or ≥10 mmHg diastolic drop) 5
• Temperature: Fever suggests infection (meningitis) 1

Neurological Examination

• Complete cranial nerve examination: Assess for focal deficits 1, 2
• Motor and sensory function: Detect focal neurological signs 2
• Cerebellar testing: Coordination assessment 2
• Neck examination: Assess for stiffness, limited flexion (meningitis) 1, 2
• Fundoscopy: Papilledema suggests increased intracranial pressure 3

Specific Examinations

• Temporal artery palpation: Tenderness, reduced pulse in giant cell arteritis (patients >50 years) 2, 4
• Scalp tenderness: Giant cell arteritis 2
• Cervical range of motion: Reduced in cervicogenic headache 1
• Myofascial tenderness: Cervicogenic headache 1

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Investigations

Screening Tools (Primary Headaches)

• ID-Migraine questionnaire (3-item): Sensitivity 0.81, specificity 0.75, positive predictive value 0.93 1, 6
• Migraine Screen Questionnaire (5-item): Sensitivity 0.93, specificity 0.81, positive predictive value 0.83 1, 6
• Headache diary: Document frequency, duration, character, triggers, accompanying symptoms, medication use 1, 6

Neuroimaging (Only When Red Flags Present)

• MRI brain with and without contrast: Preferred modality; higher resolution, no ionizing radiation; for subacute presentations or suspected tumor/inflammatory process 1, 2
• 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 2, 4
• CT head: Acute trauma or abrupt-onset headache 1, 3
• Dental panoramic radiographs: If dental pathology or sinusitis suspected 2

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 2, 4
• Morning TSH and free T4: If cold intolerance, lightheadedness present (hypothyroidism) 5
• Thyroid peroxidase (TPO) antibodies: If biochemical hypothyroidism confirmed 5

Lumbar Puncture

• Indications: CT negative but subarachnoid hemorrhage still suspected; suspected meningitis; high/low CSF pressure syndromes 1, 2, 3
• Xanthochromia spectrophotometry: 100% sensitive at 12 hours to 2 weeks post-subarachnoid hemorrhage; >70% at 3 weeks; >40% at 4 weeks 4

Expectant Findings

• Primary headaches: Normal neurological examination, normal neuroimaging 6, 3
• Subarachnoid hemorrhage: Blood on CT (if early); xanthochromia in CSF 2, 4
• Meningitis: Elevated WBC, protein in CSF; positive cultures 1
• Giant cell arteritis: Elevated ESR/CRP; temporal artery biopsy showing vasculitis (false-negative in 5-44%) 4
• Brain tumor: Mass lesion on MRI with contrast enhancement 2
• Hypothyroidism: High TSH with low free T4 5

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Empiric Treatment

Acute Migraine Treatment

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

Avoid Medication-Overuse Headache

• Limit acute medication use: Non-opioid analgesics <15 days/month; other acute medications <10 days/month 1

Tension-Type Headache

• NSAIDs or acetaminophen: For episodic attacks 1

Cluster Headache

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

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Indications to Refer

Urgent Referral to Neurology (Within 48 Hours)

• Patient unable to self-care but has help: Severe headache with disability 1
• Suspected spontaneous intracranial hypotension: Orthostatic headache pattern 1

Emergency Admission

• Patient unable to self-care without help: Severe headache with complete disability 1
• Any red flag present: Thunderclap headache, focal neurological signs, altered consciousness, unexplained fever with neck stiffness 1, 2, 3

Routine Referral to Neurology (2-4 Weeks)

• Suspected primary headache disorder: Patient able to self-care; severity determines urgency 1
• Diagnosis uncertain: Atypical features not fitting primary headache criteria 1
• First-line treatments fail: Inadequate response to empiric therapy 1

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

• Diagnosis in doubt: Complex presentation requiring subspecialty evaluation 1
• First-line treatments fail: Need for advanced therapies 1
• Rapid clinical deterioration: Progressive worsening despite treatment 1
• Serious complications: Subdural hematoma with mass effect (urgent neurosurgical referral) 1

Referral to Rheumatology

• Suspected giant cell arteritis: Patients >50 years with new-onset headache, scalp tenderness, jaw claudication, elevated ESR/CRP 2, 4

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Critical Pitfalls

Diagnostic Pitfalls

• Do not rely solely on imaging without considering complete clinical picture: History and examination guide appropriate testing 2
• Do not dismiss atypical features (e.g., metallic taste) as benign without thorough evaluation: Not typical of primary headaches 2
• Do not miss giant cell arteritis in elderly patients: Delay in treatment can cause permanent vision loss; ESR can be normal in 10-36% of cases; temporal artery biopsy false-negative in 5-44% 2, 4
• Do not order unnecessary neuroimaging for typical primary headaches without red flags: Low yield (brain tumor 0.8%, AVM 0.2%, aneurysm 0.1% in unselected headache patients); exposes to radiation (CT); can reveal incidental findings causing alarm 1, 4
• Do not miss subarachnoid hemorrhage: CT sensitivity decreases rapidly (95% day 0,50% at 1 week); perform LP if CT negative but suspicion high 2, 4
• Do not overlook medication-overuse headache: Common in chronic migraine; requires detailed medication history 1
• Do not diagnose primary headache without excluding red flags first: Life-threatening secondary causes must be ruled out 2, 6, 3

Management Pitfalls

• Do not allow acute medication overuse: Leads to medication-overuse headache (≥15 days/month non-opioid analgesics or ≥10 days/month other acute medications) 1
• Do not delay referral for suspected giant cell arteritis: Urgent ESR/CRP and rheumatology consultation required to prevent vision loss 2, 4
• Do not perform EEG for routine headache evaluation: Not useful unless seizure disorder or atypical aura suspected 1

Recognition Pitfalls

• Do not assume bilateral headache excludes serious pathology: Brain tumors and other secondary causes can present bilaterally 3
• Do not dismiss headache in patients >50 years as benign: Up to 15% of patients ≥65 years with new-onset headache have serious pathology (stroke, temporal arteritis, neoplasm, subdural hematoma) 4
• Do not ignore orthostatic headache pattern: May indicate spontaneous intracranial hypotension requiring specific treatment 1
• Do not confuse cervicogenic headache with migraine: Provoked by cervical movement (not posture), reduced cervical range of motion, myofascial tenderness 1