Early diagnosis of cluster headache, commonly considered the most painful condition on earth, is essential to curbing disability; here's what primary care clinicians need to know.
Dr McAllister is Medical Director at the New England Institute for Neurology and Headache and Chief Medical Officer for the New England Institute for Clinical Research and Ki Clinical Research, both in Stamford, Conn.
Cluster headache (CH) is known as the suicide headache for good reason, because while migraineurs suffer in quiet darkness, CH patients pace, scream, sweat, and yes, contemplate suicide as a method to deliver themselves from a headache commonly considered the most painful condition on the planet. In one study 34% of CH patients were diagnosed by primary care physicians (PCPs), an indication that PCPs need to be able to recognize and treat this primary headache disorder; proper diagnosis and a treatment plan lead to earlier control and lessen both misery and disability.
Here are 5 facts that will help you distinguish CH from other headache disorders, and guide you toward evidence-based treatment.
1. CH is a trigeminal autonomic cephalalgia (TAC). This refers to a group of short-duration primary headache disorders characterized by unilateral head or face pain with autonomic features. TACs are quite rare, though CH is most common. Other TACs include chronic paroxysmal hemicrania, SUNCT (severe unilateral neuralgiform pain with conjectival injection and tearing) and SUNA (severe unilateral neuralgia with autonomic features).
Migraine, the most common primary headache disorder after tension-type headache, is not a TAC, and although occasionally confused (patients may describe their migraines as “clustering”), CH and migraine are distinct headache syndromes.
2. Some demographics, risk factors, and triggers are known. CH is relatively uncommon, striking about 1.6 million Americans (or about as prevalent as multiple sclerosis). It typically presents in the 20s and 30s, though the range spans from early childhood to the 7th decade. Men are 3 times more commonly affected, although for unknown reasons women are increasingly being diagnosed. A family history of CH or migraine is common. Smokers are more likely to get CH than non-smokers, although we don’t know why. Alcohol is a CH trigger, as are odors, flashing lights, weather changes, and watching television. Delay in recognizing CH is common, with more than half of patients waiting 5 years for an accurate diagnosis. As noted, Rozen reported that one-third of CH patients were diagnosed by primary care physicians.
3. Duration and unique features aid in diagnosis. By definition (from the International Classification of Headache Disorders, 3rd Edition), CH lasts from 30 minutes to 3 hours. Episodic CH refers to the 85% of patients who “cluster,” with attacks occurring every other day to up to 8 per day for a finite period, ~4 to 8 weeks, followed by a variable headache-free period (months to years). Fifteen percent of CH patients never have (or stop having) a cluster-free period, and this is referred to as chronic cluster headache.
CH is side-locked, meaning exclusively unilateral, almost never crossing sides. Circadian rhythmicity (often the attacks strike at the same time each night) and autonomic features (bloodshot eye, tearing, ptosis, ipsilateral nasal congestion or discharge and ipsilateral ear fullness) round out the diagnostic features. Beware that some secondary headache (such as aneurysms, AVMs, pituitary and cavernous sinus tumors) may present phenotypically as CH. At initial presentation, consider a work-up including imaging such as MRI.
4. Unlike other headache types, oxygen can help CH. High-flow (8-15 L/min) oxygen, delivered via a non-rebreathing face mask for 15 minutes, can be an effective CH abortive. The exact mechanism remains unknown. A 2009 study by Goadsby and Burn found high-flow oxygen effective in treating 78% of cluster attacks. Side effects were non-existent. Prescribing oxygen to CH patients may be tricky, due to variations in insurance coverage, but advocating for oxygen for a CH patient is a fight well worth the effort.
5. Treatment includes bridge, preventive, and acute. When a cluster cycle begins, fast-acting (bridge) therapy is appropriate. Commonly prescribed bridge treatments include oral steroids (eg, prednisone 1mg/kg, tapering over 10 to 21 days), occipital nerve blocks with lidocaine and steroid, or naratriptan 2.5mg twice daily for a week. Preventive therapy is initiated concurrently. The mainstay CH preventive is the calcium channel blocker verapamil, although lithium, topiramate, and divalproex may also be used. When prescribing verapamil, it is important to remember that high does (480 mg to 720 mg) are often required. Preventive agents should be rapidly tapered once the cluster cycle resolves.
Acute treatment of CH needs to be fast, so injectable and nasal triptans (such as sumatriptan 3-6 mg injection and zolmitriptan 2.5-5 mg nasal spray) are most commonly prescribed, though injectable and nasal dihydroergotamine may be used as well. Neurostimulators are increasingly used in headache medicine, and the noninvasive gammaCoreTM vagus nerve stimulator has recently been approved for acute and preventive treatment of CH. Pending FDA approval are the Pulsante® implantable spheneopalatine ganglion stimulator for acute treatment of chronic CH, and the CGRP-blocking monoclonal antibody galcanezumab (Emgality), which is already approved for migraine, as a preventive treatment for episodic CH.
Cluster headache patients are out there, often un- or misdiagnosed, and they are suffering. Primary care clinicians should be on the front lines of CH diagnoses and treatment, referring those who don’t respond to standard treatments to headache specialist neurologists.
With proper recognition and therapy, we can tame that most dreaded of headache maladies, the suicide headache.
Headache Classification Committee of the International Headache Society (IHS). The International Classification of Headache Disorders, 3rd Edition. Cephalalgia. 33(9):620-808.
Matharu MS, Goadsby PJ. Cluster headache: Focus on emerging therapeutics. Expert Rev Neurotherapeutics. 2004;4:895-907.
Robbins MS, Starling AJ, Pringsheim TM, Becker WJ, Schwedt TJ. Treatment of cluster headache: The American Headache Society Evidence-Based Guidelines. Headache. 2016;56:1093-106.
Rozen TD, Fishman RS. Cluster headache in the United States of America: demographics, clinical characteristics, triggers, suicidality, and personal burden. Headache. 2011;52:99-113.
Silberstein SD, Mechtler LL, Kudrow DB, et al. Non-invasive vagus nerve stimulation for the acute treatment of cluster headache: findings from the randomized, double-blind, sham-controlled ACT1 study. Headache. 2016;56:1317-1332.