CH is associated with at least one of the following autonomic symptoms, occurring in the ipsilateral side of the head: conjunctival injection, nasal congestion, forehead and facial sweating, eyelid edema, lacrimation, rhinorrhea, ptosis, and miosis.3,13 Headaches may occur on one side of the head throughout one cluster episode, then shift to the contralateral side in subsequent periods.10 Aura occurs in 14% to 20% of patients,13,20-22 and nausea, as well as ipsilateral
visual, sensory, and speech/language disturbances have also been reported.3 Each CH attack lasts between 15 minutes and three hours, and attacks may range in frequency from one every other day to eight per day.3,13
Patients who have experienced at least five episodes of these headache symptoms, with severe pain in the specified areas and duration, accompanying autonomic symptoms, specified attack frequency, and symptoms not attributed to another disorder meet the diagnostic criteria for cluster headache given in the second edition of the International Classification of Headache Disorders (ICHD-II, 2004).3 The ICHD-II criteria, based on clinical and epidemiologic research, are recognized as a consensus guideline that is accepted worldwide to facilitate clinical practice.3 Patients who have experienced attacks fulfilling all but one of the ICHD-II criteria for CH are diagnosed with probable CH3 or cluster-like headache (CLH).23
Physical Examination
A thorough physical examination, including an investigation of the neurologic system, is essential to differentiate among primary, secondary, and other headache types. In the patient with CH, no neurologic deficits or deficits that suggest underlying disorders are usually found.3,10
Differential Diagnosis
In the evaluation of headache, it is important to differentiate CH from the other trigeminal autonomic cephalalgias: paroxysmal hemicrania (PH), short-lasting unilateral neuralgiform headache with conjunctival injection and tearing (SUNCT), and possibly hemicrania continua.3,24,25 As in CH, the pain of PH is severe, unilateral, and stabbing in quality; it, too, is associated with autonomic symptoms, often occurs at night, and can be episodic or chronic.3 However, PH headache lasts for only 2 to 30 minutes and can occur five times or more per day. Though difficult to distinguish from CH patients, those with PH usually respond to indomethacin, whereas those with CH ordinarily do not.3,8
As in patients with CH, those affected by SUNCT experience autonomic symptoms—most commonly, conjunctival injection and tearing.3,26 SUNCT differs from CH, however, in that the pain is moderate in severity, with a pulsating, burning, electric-like quality. Duration is much shorter, with episodes lasting between 5 seconds and 4 minutes.3,26
Hemicrania continua, though unilateral, is described as continuous and moderate in intensity. Like PH, it is also indomethacin-responsive.8,25,27
A broader differential diagnosis for CH, as detailed in the table,11,3,8,13,26,28 includes the other primary headaches: tension headache, migraine headache, and trigeminal neuralgia.3,26Tension headache, which affects 30% to 78% of the general population,3 is subdivided into infrequent episodic, frequent episodic, and chronic tension-type headache. Unlike CH, tension headache is mild to moderate in intensity and occurs bilaterally, with nonpulsating pressure or a tightening sensation. It is not aggravated by routine physical activity, nor is it associated with nausea, vomiting, or photophobia.
Migraine headache, also a more common primary headache type than CH,3 occurs unilaterally, is moderate to severe in intensity, and is often described as throbbing. More gradual than CH in onset, migraine is often associated with nausea, vomiting, photophobia, phonophobia, and/or visual aura. Migraine headache lacks the ipsilateral autonomic manifestations of CH, and migraineurs prefer to rest or sleep—in contrast to the extreme restlessness or agitation seen in CH patients.3
Also like CH, trigeminal neuralgia is unilateral with a trigeminal nerve distribution, and the pain can be severe and stabbing.3 However, trigeminal neuralgia lacks the autonomic symptoms associated with CH, and the pain lasts from only seconds to minutes. This headache type is often triggered by washing, shaving, or brushing teeth.3
It is also critical to exclude secondary headaches, especially those with serious causes, including meningitis, subarachnoid hemorrhage, epidural or subdural hematoma, glaucoma, tumors, temporal arteritis, or purulent sinusitis.27 Red flags associated with these conditions are:
- A complaint of the patient’s “worst headache ever” (thunderclap headache)
- First severe headache
- A subacute headache worsening over days or weeks
- An abnormal neurologic examination
- Fever or other unexplained systemic signs
- A headache preceded by vomiting
- Headache that is induced by bending, lifting, or coughing
- Headache that disturbs the patient’s sleep or presents immediately upon awakening
- History of known systemic illness
- Headache onset after age 55; and
- Pain associated with local tenderness, for example, near the temporal artery.27