Sporting a killer headache can be so overwhelming and uncomfortable at the same time. Unlike the other types of body aches and pains we routinely deal with on the go, headaches leave a person with little to almost no productivity.
Although the severity of a headache pain might be mild or severe, the overall effect that it has on your general well-being is incomparable to what other body pains cause – at least they let you carry out your daily tasks and planning peacefully!
There are different types of headaches that we all suffer from. But, interestingly, the majority of us refer to any kind of headache as just a ‘headache,’ so we do not know the exact type of headache we suffer from.
One such type of headache is ‘Cluster Headache.’ Knowing the variant of headache is essential as it lets you avoid the specific triggers that spike that particular headache up. At the same time, it can also help your doctor decide which management plan will work the best for you.
What Is A Cluster Headache?
Cluster Headache is medically referred to as ‘trigeminal autonomic neuralgia.’ Just how scary the snake sounds, these cluster headaches could become a great deal of discomfort for the suffering person, but the good news is that they are rare. 
Only 0.1% of the total population suffers from these types of headaches, and that too is because of an apparent underlying cause. Most of the affected population is in their thirties, with males being the principal target for this type of headache.
The people who suffer from cluster headaches have reported suffering from their episodes once in weeks or months with a remission time or pain-free periods that could last for years if the person is lucky enough. 
What Does A Cluster Headache Feel Like?
In medical terminology, an episode of a cluster headache is defined as ‘a unilateral (one-sided) headache that is accompanied by a symptom involving the autonomic nervous system at the same side of the aching head’. 
So, it can be said that a cluster headache is a primary headache. It is a one-sided type of headache with at least one or more symptoms that occur along with it. People who suffer from cluster headaches have reported it to be a sharp, piercing sensation on the affected side of the head.
These people have also reported experiencing severe pain around their orbital area, with the area around the eyes and the temples being the most commonly involved region during the cluster periods or episodes. 
The autonomic system symptom could be anything ranging from tears welling up in the eyes to stuffiness in the nose to a runny nose to experiencing nausea.
It is already known that these severe headaches occur in episodes. An episode can occur from one to about eight times a day. An interesting fact about cluster headache attacks is that their daily episodes occur almost at the same time of the day for as long as they last, usually at night. 
Depending upon the severity of the headache, a person can suffer from a few days to a few weeks to up to a few months with this type of headache.
How Does A Cluster Headache Develop?
As far as any headache pain is concerned, it is easy to put facts such as ‘It does not let us finish our daily tasks’ or ‘It does not let us sit quietly and peacefully in a well-lit or noisy room.’
However, the most important fact is the development of any kind of headache. Note that it is not always ‘stress’ or ‘dehydration’ or ‘a side effect of any pill’ that causes a headache to develop. With these different types of headaches, there are various reasons and theories to put forward when it comes to explaining the fundamental pathogenesis of how they develop.
The exact mechanism behind the occurrence stands out to be unclear. However, for cluster headaches, it is said that their strict ‘episodic’ or ‘routinely’ occurrence has led experts to put forward their theories related to abnormalities in the hypothalamus – the part of the brain that coordinates significant activities.
This helps interpret its circadian rhythm and why it occurs only during certain times of the year. Moreover, the parasympathetic nervous system and the trigeminovascular system have been said to get involved in the process as well. 
The trigeminovascular system comprises neurons that innervate the cerebral vessels and the dura mater with the help of some cell bodies present in the trigeminal ganglion. Moreover, these very cell bodies also contain some vasoactive peptides that further innervate some blood vessels.
Some of these vasoactive peptides include Substance P, Neurokinin A, and Calcitonin Gene-Related Peptide (CGRP), all of which are significantly increased during an episode of cluster headache. This proves that the trigeminovascular pathway is activated during cluster headaches and, therefore, plays a part in the pathogenesis of this headache. 
Cluster Headache Causes
It might be reasonable to say that cluster headache has an unclear or unsure mechanism behind its very existence.
However, as tricky as it might sound, no apparent triggers or stimuli lead to the activation of this type of headache, unlike its popular counterparts – migraine and tension-type headaches.
Because of this, it becomes difficult to reach the root cause of the headache, and so the treatment plan again becomes quite overwhelming to deal with.
However, in the field of neurology, there have been several changes, alterations, and disturbances noticed within the nervous system itself that has made it easier for healthcare professionals to reach the bottom of the problem through detailed history-taking skills only.
Enlisted below are some of the most common causes that lead to the development of cluster headaches:
As stated above, the trigeminovascular system is actively involved in the pathogenesis of the disease, and it is also seen that vasodilation almost always occurs in correlation to it. Therefore, as soon as the trigeminovascular pathway gets activated, so do its nerve fibres, and as a result, vasodilation occurs. 
However, it is also seen that whether the trigeminal nerve is involved unilaterally or entirely, in all sections, it does not seem to affect the frequency or intensity of the headache attacks in any way.
Hypothalamus And Circadian Activity
Since we already know that the hypothalamus is involved with taking care of several regulatory functions taking place all over the body, it is also essential to realize that in the context of cluster headaches, the episodes seem to be occurring in a similar circadian rhythm that the hypothalamus drives for our body. Here, the focus seems to be mainly on the occurrence of night-time episodes. 
However, it is not the hypothalamus itself that is involved in the stimulation of episodic cluster headache. In fact, the PET scan of a patient who was currently undergoing an episode of cluster headache was seen to have an activated inferior part of the hypothalamic grey matter during the episode, showing that this part might be somehow involved in the attack.
Parasympathetic Nerve Fibres
Until the last section, it was inevitable that parasympathetic nerve fibres are also involved in the pathogenesis of cluster headaches. However, when studied in terms of the episodes of cluster headaches, it was found that they are involved in taking part in imparting the symptoms of autonomic system dysfunction.
Any branch of the trigeminal nerve can get involved during this time – the ophthalmic, maxillary, and mandibular branches. However, the most commonly experienced symptoms during a cluster episode include lacrimation, eye discomfort, eye redness, nasal congestion, throat swelling, etc. These symptoms resolve as soon as the episode wanes off.
Treatment Options For Cluster Headaches
Although it is very clear from everything that cluster episodes last for a specified amount of time, it is also evident that neurologists and healthcare providers will make sure that they take every possible step to make sure that the affected person’s episodes are well-contained and controlled so as to avoid any consequences that turn severely debilitating.
Some of the commonly used medicine regimes and other options for the treatment of cluster headaches include:
100% Oxygen Therapy
The most promising and beneficial mode of therapy for cluster headaches, as well as some other types of headaches, is the employment of 100% oxygen therapy. More than half of the patients who receive this therapy show results within ten minutes of receiving it. 
Moreover, there are no side effects or life-threatening consequences of receiving either too much or too less of this oxygen therapy. So, it is entirely safe to be used on almost any and everyone suffering from cluster headaches.
Triptans such as Sumatriptan and Zolmitriptan are also used as the first-line treatment plan for cluster headaches. The route of administration of these drugs varies – they can either be delivered subcutaneously or in the form of nasal sprays, whatever is convenient for the affected person.
Triptans are usually not given orally since their oral form has a longer duration of action, and with severe pain, it might prove to be hindering for the patient.
These drugs include Ergotamine and Dihydroergotamine. They are also delivered intranasally since their mechanism of action is such that they only work in conditions of severe, throbbing pain. Therefore, they are not that effective when used in mild pain.
People suffering from chronic cluster headaches can benefit from the usage of lithium. It has been seen that lithium helps regulate the hypothalamus and keeps it away from the triggers that lead to the development of cluster headaches in a patient.
Deep Brain Stimulation
Another promising treatment option for cluster headaches involves deep brain stimulation. It works best in cases where there is a refractory cluster headache. The occipital nerve, vagus nerve, and the sphenopalatine ganglion – may all be stimulated under this treatment plan. 
So far, deep brain stimulation has only yielded successful and promising results, especially for the people for whom medical treatment was not giving good results. In other refractory cases, vagal nerve stimulation has also been employed
Other pharmacological preventive treatment options for cluster headache include Corticosteroids (Prednisone), Verapamil, Topiramate, etc.
The Bottom Line
Cluster Headache is indeed one of the most severe and debilitating types of headache disorders that can affect a person. However, this type of headache affects a very small minority of people; therefore, there is a hope that not everyone is affected by this particular type of headache, unlike tension headaches and migraines.
Cluster headaches are accompanied by other symptoms as well. Some of them are limited to the eye. In contrast, others involve the sinuses and can cause nasal stuffiness or irritation, which again adds to the discomfort that the person is already facing.
For people who suffer from these episodes after remission periods, it is best to consult a healthcare professional for medical advice and see which treatment plan best suits the severity and intensity of your cluster headache. Several treatment options for this type of headache work to improve your condition, which deteriorates once these episodes begin.
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