Definition

Cluster headache (CH) is a type of headache that occurs on one side of the head and causes pain around the eye area. It is an extremely intense type of headache with a specific pattern. Typically, sufferers of cluster headaches wake up at night due to the pain. The headache attacks can last for several months to weeks, followed by a remission period when the headache is not felt for a while. Although intense, cluster headaches are not life-threatening. The treatment for cluster headaches aims to manage the headache so that it does not last long and is not too severe. Cluster headaches are a type of primary headache, meaning they are not caused by other factors such as infection, trauma, or ruptured blood vessels.

In Asia, cluster headaches affect 3% of headache sufferers. They can occur at various ages, with the peak incidence at ages 20-29, and are more common in men.

Cluster headaches can be divided into two types based on the duration of the headache:

1. Episodic cluster headache, characterized by two episodes of cluster headache lasting 7 days to 1 year with a headache-free period of ≥1 month.
2. Chronic cluster headache, characterized by cluster headaches that occur continuously for ≥1 year without a headache-free period or with a headache-free period of <1 month.

Causes

The exact mechanism causing cluster headaches is not known. Cluster headaches are believed to be related to the trigeminal nerve, one of the branches of the brain nerves that supply the facial area. One hypothesis suggests that certain triggers activate the nerves, which the brain interprets as pain. This leads to a sensation of a one-sided headache accompanied by a runny nose and watery eyes.

Trigger factors include:

• Alcohol
• Weather changes
• Strong odors

Unlike migraines or tension-type headaches, cluster headaches are not associated with hormonal changes or stress.

Risk factor

Factors that increase the risk of cluster headaches include:

• Gender: Men are more likely to experience cluster headaches than women.
• Age: Cluster headaches typically occur in the productive age range of 20-50 years, although they can happen at any age.
• Smoking: Some people who experience cluster headaches are smokers, but quitting smoking does not impact the headaches.
• Alcohol: Alcohol increases the risk of headache attacks.
• Family History: Having a parent or sibling with cluster headaches increases the risk of experiencing them as well.

Symptoms

Cluster headaches can attack suddenly without warning symptoms, although some people feel an "aura" or nausea before the headache starts. Symptoms of cluster headaches include:

• Severe headache on one side of the head, around the eye, which can spread to the cheek, forehead, ear, and neck. This location is usually consistent in each episode.
• Pain on one side only.
• Non-throbbing pain.
• Watery eyes.
• Red eyes on the affected side.
• Blocked or runny nose.
• Sweating on the affected side of the head.
• Pale or flushed skin.
• Swelling on the affected side of the head.
• Drooping eyelids on the affected side of the head.
• The headache follows the same pattern for several consecutive days.

Diagnosis

Headaches can be a sign of other diseases. To diagnose cluster headaches, the doctor will inquire about the duration, location, quality, and pattern of the headaches. The doctor will also ensure that the headaches are not life-threatening by ruling out other possibilities such as stroke, head bleeding, and infection. To diagnose cluster headaches, the headache must meet several criteria set by The International Classification of Headache Disorders (ICHD-3), such as:

• At least five attacks fulfilling criteria B and C.
• Severe or very severe unilateral orbital, supraorbital, and/or temporal pain lasting 15-180 minutes.
• At least one of the following symptoms on the headache side:
• Red and/or watery eyes.
• Blocked and/or runny nose.
• Swollen eyelids.
• Forehead and facial sweating.
• Flushed face.
• Fullness in the ear.
• Pupil constriction (miosis) or drooping eyelid (ptosis).
• Restlessness or agitation.
• Attack frequency of one every other day to eight per day during most of the active headache period.
• No other diagnosis fits.

After the interview, the doctor needs to ensure there is no other cause for the headache. The doctor will perform a neurological examination by checking for facial, hand, and foot weakness or vision disturbances, reflexes in the hands and feet, and other checks. If needed, the doctor may order imaging tests like MRI or CT scans.

Management

 During a cluster headache attack, the doctor may provide the following treatments:

• Oxygen: Inhaling high-pressure oxygen for 15 minutes can relieve headache attacks. This procedure is relatively inexpensive and safe. You can receive this therapy in the emergency room or nearby healthcare facility.
• Triptans: Triptans are medications used to treat cluster headaches. They can be administered by injection or nasal spray. Triptans are bitter and may cause discomfort in the mouth. Consult your doctor before using this medication.
• Dihydroergotamine: This is an injectable medication that effectively reduces headaches. Consult your doctor about using this medication.

If the condition does not improve with therapy, the doctor may recommend surgery or brain nerve stimulation. However, the long-term benefits of these procedures need further research.

Complications

Cluster headaches generally do not cause life-threatening complications. However, cluster headaches can severely disrupt daily life and lead to depression. Support from family and loved ones is crucial for those with cluster headaches to manage their condition.

Prevention

There are several steps to prevent cluster headaches, such as:

• Improving sleep schedule: Regular and adequate sleep can prevent headache attacks.
• Avoiding alcohol: Alcohol can trigger cluster headache attacks.
• Limiting exposure to strong odors like perfumes, glue, etc.
• Avoiding tobacco.
• Adjusting light and sound at home to avoid triggers.

Your doctor can prescribe medications to prevent headache attacks, such as corticosteroids, lithium, and beta-receptor blockers if indicated. Consult your doctor about these options.

When to see a doctor?

Seek medical attention if you experience the above symptoms and find them disruptive. Even severe headaches can sometimes occur without underlying diseases. However, headaches can also indicate more serious conditions, such as head bleeding, infection, or tumors.

If you notice changes in your usual headache pattern or experience any of the following symptoms, see a doctor immediately:

• Sudden, very severe headache like a 'thunderclap'.
• Headache accompanied by fever, nausea, vomiting, stiff neck, seizures, confusion, weakness in hands or feet, which can indicate other conditions like meningitis or a brain tumor.
• Headache following a head injury, even if the injury feels mild.
• Headache that progressively worsens, becomes more painful or occurs more frequently.

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