Cluster Headaches

A cluster headache is a type of primary headache called a trigeminal autonomic cephalgia (or TAC).

Cephal- refers to the head, whilst -algia means pain. So, a TAC means pain in the head, arising from the trigeminal nerve, with autonomic (involuntary) signs.

The symptoms cluster in location and time, hence the name.

Cause

Currently, the exact cause is unknown. We know there is a fault between:

• the trigeminovascular system
• the hypothalamus
• the parasympathetic nerve fibres of the trigeminal autonomic reflex

But we are unsure where the error is in these interactions.

What we know so far:

• There may be unilateral (one-sided) activation of the trigeminovascular system which causes the pain.
• The hypothalamus becomes active during an attack which causes the circadian pattern and some of the autonomic features.
• The parasympathetic nerve fibres of the trigeminal autonomic reflex activate to cause the autonomic symptoms.

Key clinical features

10/10 unilateral pain in or around the eye, with at least one autonomic symptom ipsilateral (on the same side) to the pain from below:

• Blocked or runny nose
• Eyelid, forehead or facial swelling
• Red or watering eye
• Ptosis (eyelid droop) or miosis (pupil constriction)

Patients with a cluster headache sometimes experience allodynia (pain from stimuli that is usually painless) and tend to find it difficult to keep skill.

Attacks can last 15 minutes to 3 hours, up to 8 times daily, and typically occur at night. A person might have cluster headache attacks for weeks at a time, stopping for months in-between.

They cluster in time and the symptoms all cluster onto one side of the face!

Triggers:

• Sexual activity
• Stress
• Hot climate
• Alcohol
• Watching TV
• Glare
• Use of nitroglycerin compounds (like GTN spray)

Diagnosis

Diagnosis is made through history taking, using the International Classification of Headaches Disorders (ICHD) criteria:

• 5 or more attacks of severe or very severe unilateral pain in or around the eye or temples lasting 15-180 minutes and
• Headache combined with one or more of: same sided red or watering eye; blocked or runny nose; eyelid swelling; feeling of fullness in the ear; forehead and facial sweating or flushing; eyelid droop and/ or pupil constriction; feeling of restlessness or agitation.
• Episodes occur between 1 every other day – 8 daily for more than half the time during the active period of disorder.
• Another diagnosis doesn’t better suit.

It sadly sometimes takes years to diagnose, and misdiagnosis is common.

Major risk factors (who is most likely to be affected?)

The features below all increase the risk of having a cluster headache:

• Greater than 30 years old
• Drinking alcohol
• Male sex
• Previous brain surgery or trauma

Alcohol is the most common risk factor, and doctors will advise stopping drinking if you suffer from cluster headaches.

Classification

Episodic (form 80-90%)

• Attack periods last 1 to 52 weeks with remission periods lasting at least 1 month.
• The average period of attacks is 2-3 months.

Chronic (form 10-20%)

• Attack periods are greater than 52 weeks with remission periods lasting less than 1 month, or with no remission.
• Can progress from the episodic type or begin as chronic.

Treatment

Acute treatment

• 100% oxygen therapy via a non-rebreather face mask.
• Drug treatment: Injection of sumatriptan or nasal spray of sumatriptan or zolmitriptan.

Preventative treatment

• Drug treatment: verapamil is used under ECG monitoring. Lithium, oral steroids, valproic acid, melatonin and a capsaicin nasal spray can also be used.
• Avoidance of triggers.
• Deep brain stimulation of the hypothalamus
• Vagus nerve stimulation has also been shown to be effective
• Suboccipital blockade (blocks signals to the occipital muscles to reduce pain)

Complications

Due to the multi-tiered cause of cluster headaches, psychiatric disorders are commonly associated. There may also be mild slowed or increased heart rate or irregular heart rhythms from the autonomic dysfunction.

Key takeaway messages

• Cluster headaches include severe one-sided pain around the eye area with autonomic symptoms on the same side.
• Episodes can last 15 minutes to 3 hours multiple times a day, for weeks or months.
• Remission can be months to years.
• The exact cause of a cluster headache is not yet known.
• Cluster headaches can be debilitating and take time to diagnose.
• Triptans are used for immediate treatment.

References

1. https://cks.nice.org.uk/topics/headache-cluster/diagnosis/clinical-features/
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4590147/
3. https://www.ncbi.nlm.nih.gov/books/NBK544241/#!po=27.7778

Image to pair with post:

Wikimedia – an artistic interpretation of a cluster headache

Credits