Severe unilateral periorbital headache with ipsilateral autonomic features; 'suicide headache.'
Also known as: cluster headache, trigeminal autonomic cephalalgia, TAC, Horton headache
Overview
Primary headache disorder belonging to the trigeminal autonomic cephalalgias, characterized by attacks of severe strictly unilateral pain in orbital, supraorbital, and/or temporal locations lasting 15-180 minutes, accompanied by ipsilateral autonomic features and/or restlessness/agitation. Attacks occur from once every other day up to 8 times per day, often clustering over weeks-months ('cluster periods'), with remissions of months-years.
Epidemiology
Prevalence ~1 in 1000. Male-to-female ratio ~3:1 (narrowing in newer studies). Onset typically 20-40 years.
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Question 1NeurologyMedium
A 45-year-old man has severe, strictly unilateral orbital pain lasting 30-90 minutes, accompanied by ipsilateral lacrimation, rhinorrhea, and ptosis. The attacks have occurred one or more times daily in bouts for the past 6 weeks. Which of the following is the most appropriate acute treatment?
AOral verapamil therapy
BIntramuscular ketorolac
COral propranolol
DHigh-flow 100% oxygen
ENSAID with oral caffeine
Reveal answer & full explanation
Correct answer: D — High-flow 100% oxygen
AOral verapamil therapy
BIntramuscular ketorolac
COral propranolol
DHigh-flow 100% oxygen✓
ENSAID with oral caffeine
Why high-flow 100% oxygen is correct
The picture — strictly unilateral periorbital pain lasting 15 minutes to 3 hours with ipsilateral cranial autonomic features (lacrimation, rhinorrhea, ptosis) occurring in daily bouts — is a cluster headache.
High-flow 100% oxygen by non-rebreather mask aborts 70-80% of attacks within 15 minutes and is a first-line acute treatment.
Subcutaneous sumatriptan is the other first-line abortive; both act fast enough for the short, severe attacks.
Why the others are wrong
Oral propranolol — a migraine preventive, not a cluster abortive, and far too slow for an attack that peaks in minutes (right-category-wrong-headache).
NSAID with oral caffeine — useful for migraine or tension-type headache but not effective for cluster attacks (buzzword-matching on "headache").
Intramuscular ketorolac — a parenteral NSAID is a reasonable rescue for migraine but has no established efficacy in cluster headache, and its onset is far slower than oxygen or subcutaneous sumatriptan for pain that peaks within minutes (buzzword-matching on "injectable analgesic").
Oral verapamil therapy — verapamil is the first-line preventive during a cluster period, which ties it to the right headache, but it takes days to weeks of titration to suppress attacks and cannot abort an attack that peaks within minutes (right-headache-wrong-phase).
Additional high-yield points
Verapamil is first-line for prevention during a cluster period.
Question 2NeurologyEasy
A 22-year-old male has a severe headache (7/10) behind his right eye with ipsilateral tearing, rhinorrhea, and ptosis occurring daily at the same time (11 PM) for the past 3 weeks. Each episode lasts 45-90 minutes. Between episodes he is completely normal. Which of the following is the most likely diagnosis?
ACluster headache
BMigraine with aura
CParoxysmal hemicrania
DHemicrania continua
ETrigeminal neuralgia
Reveal answer & full explanation
Correct answer: A — Cluster headache
ACluster headache✓
BMigraine with aura
CParoxysmal hemicrania
DHemicrania continua
ETrigeminal neuralgia
Why Cluster headache is correct
Strictly unilateral severe periorbital pain with ipsilateral autonomic features (tearing, rhinorrhea, ptosis, miosis, conjunctival injection), duration 15–180 minutes, occurring at the same time daily in clusters for weeks is the defining presentation of cluster headache
Trigeminal neuralgia — brief electric shock-like facial pain lasting seconds, triggered by touch; no autonomic features; no clustering pattern
Migraine with aura — unilateral throbbing pain lasting 4–72 hours; associated nausea/photophobia/phonophobia; aura precedes headache; does not have ipsilateral autonomic features or clockwork periodicity
Paroxysmal hemicrania — also unilateral with autonomic features but attacks are shorter (2–30 minutes) and more frequent (5+ per day); responds absolutely to indomethacin (distinguishing feature)
Hemicrania continua — a trigeminal autonomic cephalalgia that, unlike cluster headache, responds absolutely to indomethacin; it also causes ipsilateral tearing, rhinorrhea, and ptosis, but its side-locked pain is continuous for more than 3 months with superimposed exacerbations, whereas this patient has discrete 45-90 minute attacks with complete freedom between them
Additional high-yield points
Acute treatment: 100% high-flow oxygen via non-rebreather (NRB) mask for 15–20 minutes (first-line) OR subcutaneous sumatriptan 6 mg
Prophylaxis: verapamil 240–960 mg/day is first-line; suboccipital steroid injection bridges acute cluster periods
Lithium is used for chronic cluster headache
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Alcohol — triggers attacks during a cluster period (not between periods)
Nitroglycerin and other vasodilators provoke attacks (clinical/research test)
Sleep — REM sleep particularly; many attacks occur at the same time each night
Histamine, strong odors
Pathophysiology
Activation of the trigeminal-autonomic reflex with central drive from the posterior hypothalamus (demonstrated on functional imaging) — explaining the circadian/circannual periodicity. Trigeminal activation produces severe periorbital pain; parasympathetic outflow via the facial nerve produces ipsilateral autonomic features (lacrimation, rhinorrhea, conjunctival injection). Sympathetic dysfunction may cause partial Horner syndrome (ptosis, miosis).
Clinical presentation
Symptoms
Excruciating ('worst pain imaginable,' 'ice pick in the eye') unilateral periorbital/temporal pain
Duration 15-180 minutes per attack
Frequency: 1 every other day to 8 per day, often at the same time(s) daily
Cluster period: weeks to months of frequent attacks, then remission for months to years (episodic, ~80%); chronic (~20%) has no remission >3 months
Patient is restless, pacing, agitated (NOT lying still like migraine)
Often nocturnal — wakes patient 1-2 hours after sleep onset
Signs / physical exam
Ipsilateral autonomic features during attack: conjunctival injection, lacrimation, nasal congestion, rhinorrhea, eyelid edema, forehead/facial sweating, miosis, ptosis (partial Horner — may persist between attacks)
Restlessness/agitation during attack
Normal exam between attacks
Classic findings
Severe unilateral periorbital pain + ipsilateral autonomic features + restlessness, attacks clustered in time.
Differential diagnosis
Migraine — Patient prefers to lie still in dark room; cluster patient is restless and pacing. Migraine more often bilateral, longer duration, with nausea
Other trigeminal autonomic cephalalgias — Paroxysmal hemicrania (shorter attacks 2-30 min, absolute response to indomethacin), SUNCT/SUNA (1-600 sec attacks, very frequent), hemicrania continua (continuous unilateral pain, also indomethacin-responsive)
Trigeminal neuralgia — Brief electric-shock-like pains seconds long, triggered by light touch in V2/V3 distribution; no autonomic features
Acute angle-closure glaucoma — Severe eye pain, halos around lights, fixed mid-dilated pupil, cloudy cornea, elevated IOP — ophthalmologic emergency
Sinusitis — Bilateral or maxillary pressure, nasal discharge, fever, recent URI; not as severe or paroxysmal
Pituitary tumor — Can mimic cluster; MRI brain with pituitary protocol if atypical or refractory
Diagnostic workup
Diagnostic criteria
ICHD-3: ≥5 attacks, severe unilateral orbital/supraorbital/temporal pain lasting 15-180 min (untreated), with ≥1 ipsilateral autonomic feature OR sense of restlessness, occurring once every other day to 8 per day.
Labs
Not typically helpful for diagnosis
Imaging
MRI brain with pituitary protocol recommended at least once for all patients with cluster headache to exclude structural lesion (pituitary tumor, carotid lesion, AVM)
Cluster headache vs. migraine — clinical contrast.
Treatment
First-line
Acute (abortive): high-flow 100% oxygen 12-15 L/min via non-rebreather mask for 15-20 min (works in ~70-80%; very well tolerated — no smoking or open flame near the oxygen, caution in CO2-retaining COPD)
Triptan — sumatriptan 6 mg SC (most effective formulation) or 20 mg intranasal, zolmitriptan 5-10 mg nasal — faster routes preferred because attacks are short
Avoid oral triptans (too slow)
Intranasal lidocaine 4% — adjunct
Transitional bridge therapy at start of cluster period: prednisone 60 mg taper over 2-3 weeks or suboccipital steroid injection — rapidly suppresses attacks until preventive takes effect
Second-line / adjunct
Preventive (start at the beginning of each cluster period): verapamil 240-960 mg/day (first-line; ECG monitoring for AV block as dose escalates)
Topiramate 50-200 mg/day, melatonin 10 mg at bedtime
Galcanezumab (CGRP monoclonal antibody) — FDA-approved for episodic cluster
Greater occipital nerve block
Sphenopalatine ganglion stimulation, occipital nerve stimulation, deep brain stimulation of posterior hypothalamus — for refractory chronic cluster
Avoid triggers during cluster period: alcohol, nitroglycerin, naps; smoking cessation
Complications
Severe pain leading to suicidal ideation ('suicide headache')
Depression, anxiety
Permanent partial Horner syndrome on the affected side
Medication overuse headache (less common than in migraine)
Verapamil-induced bradycardia or AV block
Disability and lost productivity during cluster periods
PANCE pearls
Cluster headache + restlessness; migraine + lying still — this behavioral feature is one of the best discriminators.
High-flow oxygen is uniquely effective and SHOULD be prescribed for home use — DME companies provide tanks for this indication.
Always image the brain (MRI with pituitary protocol) at least once — pituitary tumors can mimic cluster.
Verapamil is the preventive of choice; doses often exceed cardiology norms (up to 720-960 mg/day) — ECG before escalation and at each step.
Indomethacin-responsive headaches (paroxysmal hemicrania, hemicrania continua) must be excluded — they look like cluster but absolutely respond to indomethacin.
References
AAN 2010 — Acute and preventive pharmacologic treatment of cluster headache (Francis, Becker, Pringsheim; Neurology 2010;75:463-473)
AHS 2016 — Treatment of Cluster Headache: AHS Evidence-Based Guidelines (Robbins et al., Headache 2016)
ICHD-3 — International Classification of Headache Disorders, 3rd edition (Cephalalgia 2018)
Galcanezumab — Trial of Galcanezumab in Prevention of Episodic Cluster Headache (Goadsby et al., NEJM 2019;381:132-141)
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