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Cluster headaches
Cluster headaches are the most painful and less common among the headaches and are known as “suicide headache” because of the severity of the pain1. The pain occurs at the orbita, inside the orbita or around the orbita and nearby areas of head2. The headaches normally last between 45 minutes and 11/2 hours or can be range from15 mins to 3 hours3. The cluster headache may be episodic or chronic1. The episodic type of attacks occurs regularly for one week to one year and is separated by pain free interval periods, a range of 80-90% of patients have episodic cycles1. Chronic type of headache occurs more than one year with a pain free periods, which may lasts for one month and around 10-20% patients have this type of headaches1. Cluster headache starts at a sudden without any warning and some people experience migraine type pain. There will be deep, piercing, burning, boring and constant pain around the eye and behind the eye. Other symptoms are droopy and swollen eyelid, tearing and watering eye, pupil contraction, facial and forehead sweating, agitation and restlessness, vomiting and nausea, intolerance of light and sound1.
Prevalence
Cluster headache is an uncommon disease which affects about 0.1-0.3% of the population4. Male to female ratio is about 5:15. Cluster headache occurs in the age group of 20-50 years in male and the prevalence rate is about 0.4-1 %5. The prevalence rate in the U.S is estimated to be 2-9% for men its 0.4-1 %(6). Cluster headache begins in the adults in an age group of around 30 for men and for women it’s above 30 ranges. The cluster headache ratio in males and females was found to be 6:1 in the 1960s and now its 2:16.
Target definition and history
The effect of the serotonin metabolism with respect to the cluster headache has been poorly studied7. Some of the studies with the central seratogenic system with respect to the cluster headache pathogenesis shown that, the disease is characterized by increase in plasma seratogenic metabolism7. Serotonine seratonine is an indolamine neuro transmitter, which is synthesized from tryptophan; action in the synapse is terminated by reuptake and diffusion at selective sites, and is degraded by monamine oxidase8.
The serotonin receptors are known as 5-hydroxy tryptamine receptors (5-HT receptors). The 5-HT receptors are G-protein coupled receptors and ligand gated ion channel. There are mainly 7 types of serotonin receptors and their subtypes are there, among these 5-HT1D receptor is responsible for cluster headache. The serotonin 5-HT1D receptors were previously known as 5-HT1D alpha receptors 9. These receptors are located in the basal ganglia, cortex, spinal cord, hippocampus and vascular smooth muscle cells9. The 5-HT1D receptors are involved in anxiety, depression and other neuro psychiatric disorders and the receptor gene is located in chromosome1.