Cluster Headache Diagnosis
Cluster headache is diagnosed clinically when a patient has at least five attacks of severe unilateral orbital, supraorbital, or temporal pain lasting 15-180 minutes untreated, occurring with a frequency of one to eight attacks per day, accompanied by at least one ipsilateral autonomic symptom (lacrimation, conjunctival injection, nasal congestion, rhinorrhea, eyelid edema, forehead/facial sweating, miosis, or ptosis). 1, 2
Key Diagnostic Features
Pain Characteristics
- Strictly unilateral location: The pain must be on one side only, typically orbital, supraorbital, or temporal 3, 1
- Severe intensity: Patients describe this as excruciating, often the worst pain they've experienced 1, 2
- Duration of 15-180 minutes: This is a critical distinguishing feature—shorter than migraine (4-72 hours) and longer than most other trigeminal autonomic cephalalgias 3, 1
- Attack frequency: One to eight attacks per day during cluster periods 1, 2
Autonomic Symptoms (Must Have At Least One)
- Ipsilateral lacrimation (tearing) 3, 1
- Conjunctival injection (red eye) 3, 1
- Nasal congestion or rhinorrhea 3, 1
- Eyelid edema 3
- Forehead and facial sweating 3
- Miosis (pupil constriction) or ptosis (eyelid drooping) 3, 1
Critical diagnostic point: 98.8% of cluster headache patients have cranial autonomic features, making their absence highly unusual and warranting reconsideration of the diagnosis 4
Behavioral Features
- Restlessness or agitation: Unlike migraine patients who prefer to lie still in a dark room, 67.9% of cluster headache patients report restlessness and often pace during attacks 4, 5
- This behavioral difference is a key distinguishing feature from migraine 1
Distinguishing from Other Headache Types
Cluster Headache vs. Migraine
- Duration: Cluster headache lasts 15-180 minutes vs. migraine 4-72 hours 1
- Patient behavior: Cluster patients pace and are agitated; migraine patients lie still in dark, quiet rooms 1
- Autonomic symptoms: Prominent and ipsilateral in cluster headache; minimal or absent in migraine 1, 2
- Nausea/vomiting: Present in 27.8% of cluster patients but is a core feature of migraine 4
- Photo/phonophobia: Present in 61.2% of cluster patients but less prominent than in migraine 4
Important caveat: 23% of cluster headache patients report a typical migrainous aura preceding attacks, which can cause diagnostic confusion 4
Cluster Headache vs. Tension-Type Headache
- Location: Tension headache is bilateral with pressing/tightening quality; cluster is strictly unilateral 1
- Intensity: Tension headache is mild to moderate; cluster is severe 1
- Autonomic features: Absent in tension-type headache; required for cluster diagnosis 1
Clinical Patterns
Episodic vs. Chronic
- Episodic cluster headache: 74.8% of patients have cluster periods lasting weeks to months, separated by remission periods of at least 3 months 4
- Chronic cluster headache: 16.7% of patients have attacks occurring for more than one year without remission, or with remission periods lasting less than 3 months 4
Circadian and Circannual Patterns
- Attacks often occur at the same time each day, frequently awakening patients from sleep 2, 6
- Many patients experience seasonal patterns with cluster periods occurring at predictable times of year 6
Triggers
- Alcohol: 50% of patients report alcohol (particularly red wine in 70% of cases) triggers attacks during cluster periods 4
- Important note: Alcohol typically only triggers attacks during active cluster periods, not during remission 4
Red Flags Requiring Neuroimaging
Brain MRI with and without contrast is indicated to exclude structural mimics if any of the following are present: 1, 6
- Focal neurological deficits
- Atypical headache pattern
- Progressive worsening
- New neurological symptoms
- Abnormal neurological examination
Common pitfall: Even with a classic presentation, at least one brain MRI should be obtained to exclude secondary causes, as structural lesions can mimic cluster headache 6
Diagnostic Workup
Essential History Elements
- Five or more attacks meeting the above criteria are required for diagnosis 1
- Document frequency, duration, and temporal pattern of episodes 2
- Investigate circadian or seasonal patterns 2
- Assess for ipsilateral autonomic symptoms during attacks 1, 2
- Evaluate patient behavior during attacks (restlessness vs. lying still) 1
Physical Examination
- Complete neurological examination to identify any focal deficits 3
- Examination during an attack may reveal ipsilateral autonomic signs 1
- Normal examination between attacks is typical 3
Treatment Overview
Acute Treatment (First-Line)
- 100% oxygen at 12-15 L/min via non-rebreather mask for 15-20 minutes: Provides relief in 70-80% of patients within 15 minutes 2, 7
- Subcutaneous sumatriptan 6 mg: Provides relief in 70-82% of patients within 15 minutes 1, 8, 7
- Intranasal zolmitriptan 10 mg: Alternative acute therapy 1
Critical safety consideration: Cluster headache patients are predominantly male and over 40 years of age, which are risk factors for coronary artery disease (CAD) 8. Before prescribing sumatriptan, screen for CAD risk factors including hypertension, hypercholesterolemia, smoking (65.9% of cluster patients are current smokers), obesity, diabetes, and family history 1, 8, 4. Cardiovascular evaluation should be strongly considered if risk factors are present, and the first dose should be administered in a medically supervised setting 8.
Prophylactic Treatment (First-Line)
- Verapamil: Starting at 240-360 mg/day, titrated based on efficacy and tolerability 1, 7, 9
- ECG monitoring required for PR interval prolongation at higher doses 1
- Bridging therapy: Oral corticosteroids (at least 100 mg prednisone or equivalent daily, or up to 500 mg IV per day over 5 days) or greater occipital nerve block while verapamil takes effect 1, 7