Cluster Headache
The most likely cause of intermittent right-sided temporal headaches with lacrimation occurring in approximately 40% of cases is cluster headache, a primary trigeminal autonomic cephalgia characterized by severe unilateral orbital/temporal pain with ipsilateral autonomic symptoms including lacrimation. 1, 2
Diagnostic Criteria
Cluster headache requires five attacks meeting specific criteria: 2, 3
- Severe to very severe unilateral pain in orbital, supraorbital, or temporal region lasting 15-180 minutes 1, 4
- Attack frequency of 1-8 times daily during active cluster periods 1, 2
- Ipsilateral autonomic symptoms present in 98.8% of patients, most commonly: 5
- Restlessness or agitation during attacks (67.9% of patients pace or cannot lie still, distinguishing this from migraine where patients prefer to remain motionless) 1, 5
Clinical Pattern Recognition
The clustering pattern is pathognomonic: 2, 4
- Attacks occur in bouts (cluster periods) typically lasting 6-12 weeks 6
- Attacks demonstrate circadian rhythmicity, occurring at fixed times of day or night 6
- Episodic cluster headache (74.8% of cases) shows remission periods between bouts 5
- Chronic cluster headache (16.7% of cases) lacks significant remission periods 5
Common triggers include: 3
- Alcohol consumption (particularly red wine in 70% of cases) 5
- Nitroglycerin 3
- Foods containing nitrates 3
- Strong odors 3
Key Distinguishing Features from Other Headache Disorders
Cluster headache differs from migraine because: 2, 7
- Migraine attacks last 4-72 hours (not 15-180 minutes) 1, 2
- Migraine patients prefer lying still in dark, quiet rooms, whereas cluster headache patients are agitated and restless 2
- While 23% of cluster headache patients may report migrainous aura, the attack duration and autonomic symptoms distinguish the conditions 5
The strictly unilateral pain with ipsilateral autonomic symptoms is the hallmark that separates cluster headache from tension-type headache (which is bilateral and lacks autonomic features) 1, 7
Epidemiology Supporting This Diagnosis
- Affects less than 1% of the population but is the most common trigeminal autonomic cephalgia 3
- Male predominance of 2-3:1 (77.6% male in large cohorts) 3, 5
- Mean age of onset is 30 years 3
- High smoking rate (65.9% of patients are current smokers) 5
Critical Diagnostic Pitfalls
Misdiagnosis rates are extremely high in cluster headache: 4, 5
- Many patients experience significant diagnostic delay before receiving correct diagnosis 4
- The presence of nausea/vomiting (27.8%) and photophobia/phonophobia (61.2%) can mislead clinicians toward migraine diagnosis 5
- Do not dismiss cluster headache based on presence of migrainous features - these can coexist 5
Secondary causes must be excluded through appropriate neuroimaging, particularly when: 1, 7
- Attacks deviate from typical cluster headache pattern 4
- Neurological examination is abnormal 7
- Red flag features are present 7
Treatment Approach
Abortive therapy requires fast-acting agents because pain peaks within minutes: 8, 6
- Sumatriptan subcutaneous injection is the gold standard (81.2% effectiveness) 8, 5
- High-flow oxygen (71.1% usage rate with high effectiveness) 5, 6
Preventive therapy during cluster periods: 8, 3
- Verapamil is first-line preventive (70.3% usage, high effectiveness) 8, 5
- Glucocorticoids for transitional therapy (57.7% usage, equally high effectiveness) 8, 5
- Lithium carbonate as alternative first-line preventive 8
- Newer options include galcanezumab (monoclonal antibody against CGRP) 8, 3
For chronic refractory cases, neurostimulation procedures including occipital nerve stimulation, vagus nerve stimulation, or sphenopalatine ganglion stimulation may be considered 8, 6