By Tirtha Raj Bhandari

Cluster headache is a neurological disorder and also a primary headache. It affects 1 in per 1000 population.

What is a cluster headache?

Cluster headache is a mostly unilateral headache. It occurs in a cluster, i.e., a cycle of severely painful headaches followed by a headache-free interval. The headache cycle may range from one headache every other day to several headaches per day. Its headache intensity is more than migraine headache, i.e., it is a severe condition. Each headache episode usually lasts 30-45 minutes, but some are shorter and some longer. For example, the patient might experience up to 8 episodes in 24 hours. It can occur for weeks to several months, followed by a period of remission. Usually, it is expected before the 30s, but it can occur at any age. It usually occurs in the same season in a single patient, i.e., spring or fall, so many patients consider it a seasonal allergy. Males are affected more than females by cluster headaches.

What is the mechanism of cluster headache?

The nerve from the base of the brain gets triggered because of a signal from the hypothalamus. Hypothalamus is the headquarter of the autonomic nervous system of our body. The hypothalamus is present inside the brain and is the home of the “internal biological clock,” which has the leading role in controlling the sleep and wake cycle.

The nerve, triggered in cluster headache, is the trigeminal nerve, which has three branches that give sensory and motor supply in the face. First, which is upper branch is usually involved in cluster headache. The upper branch mainly provides supply to the forehead, scalp, and eye region. That’s why a cluster headache is also called a trigeminovascular headache.

What are the types of cluster headaches?

There are two types of cluster headaches based on the number of episodes and duration of the headache.

Episodic cluster headache occurs regularly between one week to one year, followed by a headache-free interval of one month or more.

Chronic cluster headache occurs regularly for longer than one year, followed by a headache-free interval that lasts for less than one month.

Episodic cluster headache can be converted to chronic cluster headache and vice versa.

What triggers cluster headaches?

There are two types of triggers. One type stimulates a new cycle of cluster headaches. Another type affects the headache cycle.

Change in season is considered the main cause for the beginning of a new cycle, as the hypothalamus involves producing headache, which is the circadian clock of the body. So some patients consider it as allergies or sinusitis. 

Triggers, which commonly affect the headache cycle in cluster headache, are smoking, alcohol, and strong smell.

What are the symptoms of cluster headache?

Warning sign: The patient might experience slight discomfort or burning sensation on one side of the head, but many patients cannot detect it as it progresses so fast. Cluster headache peaks within 5-10 minutes in many patients.

Pain during cluster headache has a few features, as mentioned below:

• Burning or piercing feeling in one side of the head
• Most attack occurs during the night, 1-2 hours after going to sleep
• Usually last for 15 minutes to 3 hours at a time in maximum patient
• It occurs on the same side of the head in each episode during the one cycle of headache, and it rarely shifts to another side of the head in the future.
• Headache is mainly centered behind one eye, but it can spread to the affected side’s forehead, temple, nose, and gums

• The patient can not remain still and need to pace.

Other associated features are –

Congestion: a patient might have a running nose or stuffy on the head’s affected side, i.e., only one side of the nose.

Eye problems: Eye manifestation is also seen on the affected side of the head only. Common eye manifestations are drooping eyelids, eye pain, or watering eyes. Sometimes pupils may look more petite.

Face changes: Sweating and flushing face on the affected side of the head.

When to go to the doctor or hospital immediately?

Suppose headache is associated with red flag signs. In that case, there might be some deadly things in your brain, so meet the doctor immediately. Red flag signs of headache are,

• An abrupt and severe headache that is  like a thunderclap
• Headache with feelings of fever, neck stiffness, confusion, double vision, numbness or weakness in any part of the body, convulsions, which could be a sign of a stroke
• Headache after a head injury
• A chronic headache get worse after coughing, exertion, straining, or a sudden movement.

How to diagnose cluster headache?

It is a primary headache, so there is no blood test or imaging to diagnose it. Instead, a neurologist or pain specialist only diagnoses it based on clinical features. But the patient might need to do some blood tests and imaging of the head (CT or MRI) to rule out other causes of secondary headache.

How can cluster headaches be treated or prevented at home?

Avoid triggers that affect cluster headaches like alcohol, smoking, and a strong smell. Maintain good sleep hygiene. If you have sleep apnea, get it treated by CPAP and reduce weight.

How can cluster headaches be treated?

Two treatments are there for cluster headaches. One is pain-relieving medication (abortive treatment), another is prophylactic medication (preventive medicine)

Abortive medication:

• Giving 100% oxygen at the beginning of the headache episode will relieve pain.
• Tryptophan medication like sumatriptan and rizatriptan relieves headaches by constricting the blood vessel of the head.
• Local application of capsaicin cream in the affected area of the head gives pain relief.
• Dihydroergotamine (DHE) injection gives pain relief within 5 minutes. However, it should not be given with the triptan group of the drug.

Prophylactic medication?

Prophylactic medication reduces the frequency and severity of cluster headaches. Commonlyused medicines for prevention of cluster headache are-

• Blood pressure medication like- propranolol, verapamil
• Antidepressants like Amitriptyline
• Steroid like prednisolone works by reducing nerve inflammation
• Muscle relaxants like baclofen
• Anti-seizure drugs like topiramate, valproic acid
• Ergotamine

Is there any intervention that is beneficial in cluster headaches?

Sphenopalatine ganglion block or radiofrequency ablation is found beneficial in cluster headaches. It helps in reducing attacks, sometimes complete relief from cluster headaches. It is found helpful in another type of headache like chronic migraine also. But its role in cluster headache relief is better than other types of headache.

Who does sphenopalatine ganglion block?

Interventional pain physicians are trained for performing the sphenopalatine block. Sphenopalatine ganglia are situated on the lateral side of the nose, outside the brain. Therefore, this procedure can be done only under local anesthesia. The patient might feel some pricking pain during the procedure.