Cluster Headache

Cluster headache is a neurological disorder characterised by recurrent severe headaches on one side of the head, typically around the eye. These headaches are often accompanied by eye watering, nasal congestion, or swelling around the eye on the affected side.

The pain is severe, described as burning, stabbing, or drilling, and may lead to suicidal thoughts, thus earning the nickname "suicide headaches". Attacks last between 15 minutes and 3 hours and often occur in clusters that last for weeks or months.

Signs and Symptoms

Cluster headaches are characterised by recurring severe unilateral headache attacks, typically lasting 15 to 180 minutes. Women may experience longer and more severe attacks. The pain is unilateral, occurring around or behind the eye or in the temple, and is described as burning, stabbing, or squeezing.

Accompanying symptoms may include drooping eyelid, pupil constriction, redness of the conjunctiva, tearing, runny nose, facial blushing, swelling, or sweating on the same side of the head as the pain. Sensitivity to light (photophobia) or noise (phonophobia) may occur, and nausea is rare but possible. Restlessness and secondary effects like physical exhaustion, confusion, and depression are common.

Causes

The cause of cluster headaches is unknown but is likely related to dysfunction in the posterior hypothalamus. Risk factors include tobacco smoke and family history. Genetic factors and the involvement of the hypothalamus, particularly the suprachiasmatic nucleus, are suspected. Imaging studies, such as PET scans, show brain areas activated during pain.

Diagnosis

Diagnosis is primarily based on the patient's symptoms and a detailed oral history. A headache diary can be useful in tracking occurrences, severity, and duration of headaches. Misdiagnosis is common, with cluster headaches often being mistaken for migraines or sinusitis. Differential diagnosis includes chronic paroxysmal hemicrania, hemicrania continua, SUNCT, and trigeminal neuralgia.

Prevention

Preventive treatments aim to reduce or eliminate attacks and are often used alongside abortive and transitional therapies. Verapamil, a calcium channel blocker, is the first-line preventive therapy. Glucocorticoids like prednisone may be used for short-term relief. Surgical options, such as deep brain stimulation or occipital nerve stimulation, are considered for those who do not respond to medications.

Other treatments like lithium, methysergide, and topiramate are alternative options, although evidence supporting their use is limited.

Management

The primary treatments for acute cluster headaches are oxygen therapy and triptans. Oxygen is administered via a non-rebreather mask at 12–15 litres per minute, helping to abort attacks within 15 minutes for about 70% of patients. Triptans, like subcutaneous or intranasal sumatriptan, are effective for acute attacks.

Opioids are not recommended due to the risk of dependency and worsening headache syndromes. Intranasal lidocaine and sub-occipital steroid injections are also used for relief.

Epidemiology

Cluster headaches affect about 0.1% of the population at some point in their life, with men being four times more likely to be affected than women. The condition usually starts between the ages of 20 and 50, though it can occur at any age. Around one in five adults report onset between 10 and 19 years.

History

The first complete description of cluster headache was given by London neurologist Wilfred Harris in 1926. The condition was initially called Horton's cephalalgia after Bayard Taylor Horton, who described the severity of the headaches and the associated risk of suicide in his 1939 paper.

Research Directions

Recent research has looked at the use of tryptamines like LSD and psilocybin to abort attacks and interrupt cluster headache cycles. Preliminary findings suggest these substances may lead to extended remission periods, although more controlled studies are needed to confirm their efficacy. Other potential treatments under investigation include fremanezumab, a monoclonal antibody targeting calcitonin gene-related peptides.

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Self-assessment MCQs (single best answer)

Which nerve is thought to play an important role in cluster headaches?

What is the typical duration of a cluster headache attack?

Which of the following symptoms is rare in cluster headaches?

What area of the brain is likely involved in the cause of cluster headaches?

What is the first-line preventive therapy for cluster headaches?

Which treatment is NOT recommended for acute cluster headache management due to the risk of dependency?

Which demographic is four times more likely to be affected by cluster headaches?

Around what percentage of the population is affected by cluster headaches at some point in their life?

Who gave the first complete description of cluster headaches?

What recent research direction involves substances like LSD and psilocybin for cluster headache treatment?