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That is, people with migraine illness have a nervous system that is not working normally. It overreacts to stimuli and, when stimulated, there is an unusual wave of brain activity that leads to a headache.
Almost all migraine sufferers have a problem with a specific part of the nervous system, called the trigeminal nerve. The trigeminal nerve is a network of wiring that attaches to special sensors.
When stimulated, they send electrical signals to the brainstem with connections to nerves of the cortex and its covering, the dura. Normally this system allows us know what is going on in the world.
When the system does not work properly, electrical signals set off a slowly moving wave of electrochemical activity across the surface of the brain. Migraineurs start to experience odd sensations, such as white sparks in an eye (a misfiring of the ocular nerve) followed by an intense pain in some part of the head and concluding with a long period of nausea (activation of the gastrointestinal system) and exhaustion (general inflammation and swelling of the cortex).
This abnormal wave of electrochemical activity Is often stimulated by several different stimuli. These stimuli are irrational signals from other parts of the nervous system, such as stress, irregular sleep, a flashing light, a range of food ingredients, weather changes, and noise. Sometimes the migraine symptoms occur spontaneously, without a trigger.
The majority of migraineurs are borne with a defective nervous system. It is clear that migraine disorders occur within families, but the details of the genetics have been difficult to figure out because migraine disease is not one or two gene mutations. Already researchers have identified more than 20 irregular chromosome segments associated with migraine. Each potential genetic error affects how nerve cells work in a different way.
The brainstem is a complex intersection of nervous system wiring at the base of our brain. It is here that information collected from all of our body congregates in important clusters of cell bodies called nuclei. From the nuclei, new signals are rerouted to other parts of the brainstem and the rest of the brain. It is within the brainstem that we find nuclei that control pain, stress, balance, mood, sleep and the autonomic system. It is the interaction of these neighboring nuclei that may explain the wide array of disorders in migraineurs.
Migraine illness can evolve from an occasional intense event to one of frequent annoying, sometimes debilitating symptoms. One explanation is that with each migraine headache or event, there is an inflammatory reaction. This is partly because migraine illness affects not only nerve cells but the adjacent blood vessels and our immune systems. Although the details of this interaction are not yet known, it is understood that the chemicals that are released from nerve ending cause both blood vessels to swell, contract and become leaky and the immune system to become active. Together they cause inflammation within the brain. Over time, repeated inflammation causes damage and changes to the neural circuitry.
The final concept is that sex hormones have a profound effect on our nervous system. Migraine is a burden on work productivity, relationships and personal enjoyment of life and it is borne most heavily by women. Young boys and girls are afflicted equally with migraine symptoms, but, with the onset of puberty, there are three times as many female suffering from migraines as males. And the hormonal fluctuations of menopause shifts the balance of symptoms from headaches to feelings of facial and ear pressure, imbalance, body aches, sleep disorders and fatigue.
Migraine illness is a complicated neurologic condition. It affects many parts of the nervous system and causes many non-headache symptoms.
To study migraine is to study almost every aspect of how nerves work. With more research, we can expect
Broader definitions of migraine that better represent malfunctions of the entire nervous system and less on headache variants
Improved diagnosis of migraine disorders
More individualized treatment