Trigeminal autonomic cephalalgias (TACs) are a distinct set of headache disorders characterized by short-lasting headache attacks with severe unilateral pain in the trigeminal area. One of the classic TACs is cluster headache, where patients describe their pain as the most severe ever experienced.

The unilateral headache pain associated with cluster headache is often confused with migraine. Although similar in some ways in terms of their pathophysiology and clinical presentation, their management differs. It is crucial to diagnose cluster headache and migraine accurately so that patients may be relieved of debilitating symptoms.

What is cluster headache?  

Cluster headache is an uncommon headache disease with an estimated lifetime prevalence of 0.12 percent. It is characterized by sudden, severe unilateral pain with ipsilateral autonomic symptoms. Cluster headache attacks are short but occur in “clusters” with multiple attacks over a period of four-12 weeks. These “clusters” are followed by pain-free remission periods that can last for months or even years. Cluster duration and associated remission depends on the type of cluster headache, whether episodic (lasting anywhere from one week to a full year and having a long remission period) or chronic (lasting longer than a year and having a short or no remission period).  

Although cluster headache is less common than migraine, which has a reported global prevalence of 11.6 percent, there are similarities in clinical presentation that can lead to misdiagnosis.  

Clinical presentation of cluster headache: 

Patients with cluster headache describe extremely painful unilateral headaches that are side-locked, lasting 15-180 minutes. The headache attacks are frequent (occurring once or several times per day), reaching a maximum pain intensity quickly and then stopping abruptly. Headache pain is localized around or behind the ipsilateral eye. Autonomic symptoms frequently occur on the same side of the headache pain and include swelling around the eye, sweating on the face and forehead, nasal congestion, runny nose, tearing, pupillary constriction, and eyelid droop. Patients often attempt to relieve their pain and restlessness with movements such as simple rocking or pacing, or through physical activity like going for a run or doing push-ups.

Since patients can experience migraine-like symptoms during clusters—including sensitivity to light and sound, nausea, vomiting, migraine-like aura, and headaches prompted by certain triggers—these similarities to migraine contribute to the misdiagnosis of cluster headache.

Steps towards the differential diagnosis of cluster headache and migraine: 

Although the clinical presentation of cluster headache and migraine may be similar, there are steps to accurately diagnose patients presenting with unilateral headache pain.

The diagnosis of cluster headache vs. migraine is best performed with the International Classification of Headache Disorders, Third Edition (ICHD-3), which has distinct criteria for each, with key differentiating characteristics. 

  • Cluster headache attacks last less than three hours, while migraine attacks last longer than four hours. 
  • Cluster headache attacks involve pain described as stabbing or searing while migraine headache attacks involve pain that is pulsing, pounding, or throbbing. 
  • Cluster headache attacks are accompanied by restlessness and increased physical activity, while migraine attacks are aggravated by physical activity and patients tend to rest quietly in a dark place. 
  • Cluster headache attacks are accompanied by autonomic symptoms on the same side of the headache, which is an uncommon occurrence with migraine. 
  • Cluster headache attacks often wake patients one-two hours after going to sleep, while most patients with migraine have headaches typically in the morning upon waking up. 

In patients with suspected cluster headache, the mnemonic SEAR can help to identify cluster headache features and signs quickly. 

Side-locked, as the headache pain is unilateral and only on one side of the head. 

Excruciating, as the headache pain is perceived as extremely painful. 

Agitating, as the patient becomes agitated or restless when a headache attack starts. 

Regularly recurring, as the headaches occur in a rhythm with certain predictability. 

Once a diagnosis of cluster headache is confirmed, management focuses on reducing the frequency, intensity, and duration of attacks, typically through oxygen therapy and medications, such as triptans and verapamil. Patients refractory to these treatments may require noninvasive and/or invasive neurostimulation to relieve their symptoms.  

For information to share with your patients, see DynaMedex Patient Information for Cluster Headache.

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