Headache

Headache is pain felt in the head above the orbitomeatal line. Most presentations are primary headache disorders.

Anatomy and mechanism. Pain arises from the meninges, dural sinuses and large intracranial vessels, periosteum, scalp and neck muscles, and the trigeminal, glossopharyngeal, vagal and upper cervical (C1 to C3) afferents. Brain parenchyma itself is pain insensitive. Migraine involves activation of the trigeminovascular system with release of calcitonin gene related peptide.

Classification. Primary: migraine, tension type headache, trigeminal autonomic cephalalgias and other primary disorders. Secondary: headache attributed to vascular, infective, structural, raised or lowered intracranial pressure, drug, metabolic, ocular, ENT, dental or cervical causes.

Temporal patterns. Acute new headache, recurrent episodic headache and chronic daily headache (15 or more days each month for over 3 months) have different differentials and different management, and are handled as separate sections.

Key distinctions. Time to peak intensity, new onset after age 50, progressive course, positional behaviour and neurological or systemic signs separate secondary from primary headache.

• Medication overuse: simple analgesics on 15 or more days each month, or triptans, opioids or combination analgesics on 10 or more days each month, for over 3 months.

History. Establish age at onset, time to peak, duration, frequency, site, quality, severity, triggers, and any change from the usual pattern. Ask about aura (visual, sensory or speech symptoms developing over 5 or more minutes and lasting up to 60 minutes), nausea, photophobia and phonophobia, and autonomic features (lacrimation, conjunctival injection, nasal congestion, ptosis, restlessness).

Ask whether pain is worse lying flat or on waking (raised pressure), worse upright (low pressure), or provoked by cough, strain, exertion or sexual activity. Ask about jaw claudication, scalp tenderness, visual symptoms, fever, rash, head or neck trauma, and recent dental or sinus symptoms.

Risk factors and background. Pregnancy or postpartum state, hypertension, cancer, HIV, immunosuppression, anticoagulant use, sleep apnoea, coagulopathy, prior stroke, family history of aneurysm or migraine. Record every analgesic taken with days of use each month, and caffeine, alcohol and vasoactive drug use (nitrates, calcium channel blockers, phosphodiesterase inhibitors, oral contraceptives, ergots, decongestants).

Examination. Blood pressure, temperature, pulse, and a full neurological examination: fundi for papilloedema, visual fields, pupils, eye movements, cranial nerves, limb power, tone, reflexes, cerebellar signs and gait. Examine for neck stiffness, temporal artery tenderness and pulses, sinuses, temporomandibular joints, cervical spine range, scalp and skin. Check the eyes for a red, hazy cornea with a fixed mid-dilated pupil.

Red flags

• Sudden onset reaching peak within one minute
• New headache after age 50, or a change in established pattern
• Progressive course over days to weeks
• Fever, neck stiffness, rash, or immunosuppression
• Papilloedema, focal deficit, seizure, reduced consciousness or new cognitive change
• Worse on waking, lying down, coughing or straining
• Jaw claudication, scalp tenderness, visual symptoms, or polymyalgic features
• Head injury within 3 months, anticoagulation, cancer, HIV
• Pregnancy or postpartum with hypertension
• Exertional or sexual onset, or carbon monoxide exposure (household clusters, winter heating)
• Red, painful eye with halos

Special groups. Pregnancy: new headache with blood pressure of 140/90 mmHg or more after 20 weeks needs pre-eclampsia excluded, and venous sinus thrombosis is more common postpartum. Older adults: new headache is secondary until proven otherwise. Region specific: in malaria endemic areas every febrile headache needs a malaria test.

Primary headache

• Migraine with and without aura: recurrent attacks of 4 to 72 hours, unilateral, pulsating, moderate to severe, worse on movement, with nausea or photophobia and phonophobia.
• Tension type headache: bilateral, pressing, mild to moderate, no nausea, not worsened by activity.
• Cluster headache: strictly unilateral orbital pain lasting 15 to 180 minutes, with ipsilateral autonomic signs and restlessness, occurring up to 8 times daily in bouts.
• Paroxysmal hemicrania, SUNCT and SUNA, and hemicrania continua: short or continuous strictly unilateral pain with autonomic features; paroxysmal hemicrania and hemicrania continua respond completely to indomethacin.
• Primary cough, exertional, sexual, stabbing and hypnic headaches, and new daily persistent headache.

Secondary, vascular

• Subarachnoid haemorrhage, intracerebral haemorrhage, ischaemic stroke
• Cervical artery dissection (neck pain, Horner syndrome)
• Cerebral venous sinus thrombosis
• Reversible cerebral vasoconstriction syndrome
• Giant cell arteritis
• Pituitary apoplexy
• Hypertensive emergency and posterior reversible encephalopathy syndrome

Secondary, infective

• Meningitis, encephalitis, brain abscess, subdural empyema
• Acute bacterial sinusitis with complications
• Malaria and other systemic febrile illness

Secondary, intracranial pressure and structural

• Intracranial tumour and metastases, subdural haematoma
• Hydrocephalus, colloid cyst
• Idiopathic intracranial hypertension
• Spontaneous intracranial hypotension and post dural puncture headache

Secondary, other

• Medication overuse headache and drug induced headache
• Carbon monoxide poisoning, hypoxia, hypercapnia, sleep apnoea headache
• Acute angle closure glaucoma, optic neuritis
• Cervicogenic headache, temporomandibular disorder
• Pre-eclampsia and eclampsia
• Phaeochromocytoma
• Post traumatic headache
• Caffeine and alcohol withdrawal

Stepwise reasoning. First exclude an emergency using the red flags. Then classify by pattern. Then decide whether imaging or lumbar puncture is needed.

First line. Blood pressure, temperature, capillary glucose, fundoscopy and a full neurological examination. Typical migraine or tension type headache with a normal examination and no red flags needs no imaging and no blood tests.

Imaging. Non-contrast CT head immediately for sudden severe onset, head trauma, anticoagulation, reduced consciousness or acute focal deficit. MRI brain with contrast for progressive headache, papilloedema, new neurological signs, new headache in cancer or HIV, and suspected posterior fossa, pituitary or intracranial hypotension pathology. CT or MR venography for suspected venous sinus thrombosis. CT or MR angiography for suspected dissection or reversible vasoconstriction.

Lumbar puncture. After CT excludes mass effect: suspected meningitis, encephalitis, subarachnoid haemorrhage with a normal CT more than 6 hours after onset (at least 12 hours after onset for xanthochromia), and suspected idiopathic intracranial hypertension (opening pressure over 25 cmH2O in adults is abnormal). Do not delay antibiotics for imaging or puncture when meningitis is suspected.

Blood tests. For age over 50 with new headache: ESR and CRP (ESR over 50 mm/h supports giant cell arteritis, but a normal value does not exclude it). Add full blood count, urea, creatinine, glucose, and a malaria test where relevant. Temporal artery ultrasound or biopsy confirms giant cell arteritis; biopsy remains useful up to 2 weeks after steroids start.

Other tests. Intraocular pressure measurement for suspected angle closure. Carboxyhaemoglobin for suspected carbon monoxide exposure. Urine protein and blood pressure series in pregnancy.

Immediate management of secondary causes

• Suspected bacterial meningitis: ceftriaxone 2 g IV every 12 hours, with dexamethasone 10 mg IV every 6 hours for 4 days (first dose before or with the antibiotic). Add ampicillin 2 g IV every 4 hours if age over 60 or immunocompromised. Add aciclovir 10 mg/kg IV every 8 hours if encephalitis is suspected, with adjustment for renal function.
• Suspected giant cell arteritis: prednisolone 40 to 60 mg orally each morning started before biopsy, with aspirin 75 mg daily. If visual symptoms are present, methylprednisolone 500 mg to 1 g IV daily for 3 days. Give a proton pump inhibitor and bone protection. Same day specialist review.
• Suspected subarachnoid haemorrhage, pituitary apoplexy, venous sinus thrombosis, dissection or stroke: emergency CT, then neurosurgical or stroke referral.

Acute migraine (stepped, treat early in the headache phase)

• Aspirin 900 mg orally as a single dose, repeated after 4 to 6 hours if needed; maximum 4 g in 24 hours. Avoid in peptic ulcer, bleeding disorders and children under 16.
• Ibuprofen 400 to 600 mg orally at onset, repeated after 6 to 8 hours; maximum 2.4 g in 24 hours. Avoid in renal impairment, heart failure, peptic ulcer and the third trimester; monitor renal function with repeated use.
• Paracetamol 1 g orally every 4 to 6 hours; maximum 4 g in 24 hours. Reduce to a maximum of 2 g in 24 hours with weight under 50 kg, chronic alcohol use or liver disease.
• Sumatriptan 50 to 100 mg orally at onset, repeated after at least 2 hours if the first dose helped; maximum 300 mg in 24 hours. Subcutaneous 6 mg, repeated after at least 1 hour; maximum 12 mg in 24 hours. Contraindicated in ischaemic heart disease, stroke or TIA, uncontrolled hypertension, peripheral vascular disease, hemiplegic or basilar migraine, within 24 hours of ergot use, and within 2 weeks of a monoamine oxidase inhibitor. Do not give during aura alone.
• Metoclopramide 10 mg orally, IM or IV every 8 hours for nausea and to speed absorption; maximum 30 mg in 24 hours and 5 days of use. Halve the dose when creatinine clearance is under 60 mL/min and reduce further when under 15 mL/min. Risk of acute dystonia in young adults.
• Emergency department refractory attack: metoclopramide 10 mg IV, IV fluid, and dexamethasone 10 mg IV as a single dose to reduce early recurrence (evidence is modest).

Migraine prevention is indicated for 4 or more headache days each month, disabling attacks, or contraindication to acute drugs. Review at 8 to 12 weeks at a stable dose.

• Propranolol 40 mg orally twice daily, increased every 2 weeks to a usual 80 to 160 mg daily; maximum 240 mg daily. Avoid in asthma, heart block and bradycardia. Monitor pulse and blood pressure.
• Amitriptyline 10 mg orally at night, increased by 10 mg each week to 25 to 75 mg at night. Monitor for sedation, urinary retention and QT prolongation.
• Topiramate 25 mg orally at night, increased by 25 mg each week to 50 mg twice daily. Halve the dose when creatinine clearance is under 70 mL/min. Teratogenic; reduces efficacy of hormonal contraception at higher doses; risk of kidney stones, angle closure glaucoma and metabolic acidosis.
• Valproate is not used in women who could become pregnant.

Tension type headache. For episodic attacks: paracetamol 1 g orally every 4 to 6 hours (maximum 4 g in 24 hours) or ibuprofen 400 to 600 mg orally every 6 to 8 hours (maximum 2.4 g in 24 hours). For chronic tension type headache, amitriptyline 10 mg at night increased by 10 mg weekly to 25 to 50 mg.

Cluster headache

• Acute: 100 percent oxygen 12 to 15 L/min by non-rebreather mask for 15 minutes, and sumatriptan 6 mg subcutaneously, repeated after 1 hour; maximum 12 mg in 24 hours.
• Prevention: verapamil 80 mg orally three times daily, increased by 80 mg every 2 weeks to 240 to 480 mg daily, with an ECG before each increase (PR interval). A short oral prednisolone course starting at 60 mg daily for 5 days, then reducing by 10 mg every 2 days, bridges until verapamil works (evidence is limited). Specialist referral.

Medication overuse headache. Stop the overused drug abruptly, expect worsening for 2 to 10 days, start a preventive drug, and review at 4 to 6 weeks.

Special groups. Pregnancy: paracetamol first line; sumatriptan has reassuring data; avoid NSAIDs after 20 weeks, and topiramate and valproate throughout. Breastfeeding: ibuprofen, paracetamol and sumatriptan are compatible.

Monitoring. Headache diary of days, severity, drugs taken, and triggers. Review preventive drug at 8 to 12 weeks.

Referral and escalation. Immediate emergency referral for any red flag with a possible vascular, infective or compressive cause. Urgent neurology for cluster and other trigeminal autonomic headaches, suspected idiopathic intracranial hypertension (with ophthalmology for visual field and acuity), and refractory migraine after 2 adequate preventives.

Admission criteria. Any confirmed or suspected secondary cause, status migrainosus over 72 hours, intractable vomiting, or diagnostic uncertainty with red flags.

Discharge and safety netting. Return urgently for sudden severe headache, new weakness, speech or visual change, fever with neck stiffness, drowsiness or seizure. Follow up in 4 to 6 weeks.