What are the characteristics of cluster headaches (also known as episodic cluster headaches)?

From the Guidelines

Cluster headache is a rare and debilitating condition characterized by severe, unilateral orbital or periorbital pain, typically lasting 15-180 minutes, with frequency of 1-8 episodes per day 1.

Key Characteristics

• Severe unilateral pain: lasting 15-180 minutes 1
• Frequency: 1-8 episodes per day 1
• Accompanying symptoms:
  • Ipsilateral cranial autonomic symptoms, such as conjunctival injection, lacrimation, and nasal congestion 1
  • Forehead and/or facial sweating, ptosis, miosis, and eyelid edema 1

Diagnosis and Differential Diagnosis

Cluster headache should be distinguished from other primary headache disorders, such as tension-type headache and migraine, as well as secondary headache disorders, such as medication-overuse headache 1.

Important Considerations

A thorough medical history and physical examination are essential to diagnose cluster headache and rule out other potential causes of headache 1.

From the FDA Drug Label

The efficacy of IMITREX Injection in the acute treatment of cluster headache was demonstrated in 2 randomized, double-blind, placebo-controlled, 2-period crossover trials. Patients age 21 to 65 were enrolled and were instructed to treat a moderate to very severe headache within 10 minutes of onset Headache relief was defined as a reduction in headache severity to mild or no pain. In both trials, the proportion of individuals gaining relief at 10 or 15 minutes was significantly greater among patients receiving 6 mg of IMITREX Injection compared with those who received placebo

The characteristics of cluster headaches are not explicitly described in the provided text, but it can be inferred that they are:

• Moderate to very severe in intensity
• Treated within 10 minutes of onset
• Defined by a reduction in headache severity to mild or no pain after treatment
• Typically occur in patients age 21 to 65 2

From the Research

Characteristics of Cluster Headaches

• Cluster headaches are a primary headache disease characterized by recurrent short-lasting attacks (15 to 180 minutes) of excruciating unilateral periorbital pain accompanied by ipsilateral autonomic signs 3
• The pain is associated with ipsilateral conjunctival injection, lacrimation, nasal congestion, rhinorrhea, forehead and facial sweating, miosis, ptosis and/or eyelid edema, and/or with restlessness or agitation 4
• Cluster headaches can be episodic or chronic, depending on the presence of remission periods 3
• Episodic cluster headaches occur in clusters of weeks to months duration, whereas chronic cluster headaches attacks occur for more than 1 year without remissions 5

Demographics and Prevalence

• Cluster headaches affect young adults, predominantly males 3
• The prevalence of cluster headaches is estimated at 0.5-1.0/1,000 3 or 0.1% 5, 6

Triggers and Patterns

• Alcohol is the only dietary trigger of cluster headaches, strong odors (mainly solvents and cigarette smoke) and napping may also trigger attacks 3
• Cluster headaches have a circannual and circadian periodicity, with attacks being clustered in bouts that can occur during specific months of the year 3
• During bouts, attacks may happen at precise hours, especially during the night 3

Pathophysiology

• The understanding of the pathophysiological mechanisms behind cluster headaches is far from complete, but it is considered to be a neurovascular and chronobiologic headache disorder, with a pivotal role played by the central brain mechanisms 4
• The hypothalamus has been confirmed to be involved in cluster headaches, explaining the cyclic aspects of the disease 3
• Genetic factors play a role in cluster headache susceptibility, and a causative role has been suggested for the hypocretin receptor gene 3