All primary headaches are in need of better treatments. The most important primary headaches (i.e. independent disorders that are not caused by another disease) are migraine, tension-type headache and cluster headache. Migraine has a prevalence of 10% in the general population with a lifetime prevalence of 13% in men and 33% in women. Migraine is a highly disabling disease with high personal and social costs. To date, the precise mechanisms underlying the pathophysiology of migraine have remained elusive. Migraine strikes people during what are expected to be their most productive years: between ages 20 and 40 for most women, with a slightly higher age range for men. Migraine is typically characterized by unilateral onset of head pain, severe progressive intensity of pain, throbbing or pounding, and interference with the person's routine activities. Accompanying symptoms of photophobia (sensitivity to light) or phonosensitivity (intolerance to noise), as well as nausea and/or vomiting, are common, and often leads to the inability to perform daily tasks. A large portion of people with migraine often have no accompanying pain, their predominant symptom instead being vertigo (a spinning sensation) or dizziness/disequilibrium (balance loss), mental confusion, disorientation, dysarthria, visual distortion or altered visual clarity, or extremity paresis. Patients with migraine associated vertigo (MAV) are often seen by audiologists and vestibular rehabilitation therapists for evaluation and treatment. Because the exact mechanisms of migraine are still not completely understood, the management of migraine dizziness presently includes a combination of medications, vestibular rehabilitation, and lifestyle modifications that include limitation of risk factors associated with migraine (those related to diet, sleep, stress, exercise, and environmental factors).
Migraine is a disease associated with increased synthesis and release of calcitonin gene related peptide (CGRP) and a migraine attack can be blocked with CGRP antagonists. The actual pain is generated by nociceptors of trigeminal nerve endings in the dura. Low serotonin levels may sensitize the nociceptors of trigeminal neurons. Triptans and ergotamins, which decrease serotonin, are associated with relief of acute pain. In contrast, tricyclic antidepressants and selective serotonin and noradrenaline reuptake inhibitors, which are associated with increases in serotonin, are utilized for migraine prevention.
Migraine attacks can be triggered by intrinsic cerebral factors (e.g. calcitonin gene related peptide (CGRP) release), nitric oxide like tri-nitroglycerine, corticotrophin releasing hormone (stress), pro-inflammatory cytokines, and degranulation of mast cells located in the dura. While migraine has a genetic background, twin studies reveal that the cause of a majority of migraines appears to be due to environmental factors. The mechanism of triggering migraine is, however, still not understood. The cause of both migraines and chronic dizziness has eluded investigators for centuries and it therefore presents a truly long felt but unsolved mystery as to its causation and treatment.