What Physically happens inside our heads when we have a Migrane ?

Question

I know that a cold / flu is caused by a virus, and the symptoms are our body's way of fighting it, and I know that tummy bugs are caused by bacteria in our gut so we feel sick, but, when we have a migrane, we get headaces, blindness or blurred vision, sore joints, numbness, wierd feelings, so, what EXACTLY is happening to us when we have a migrane ?

Answer 1

The blood vessels on the surface of your brain dilate, and with each heartbeat, the blood surging through throws the dilated blood vessel wall up against your skull, resulting in that throbbing pounding pain.

waves of electrical changes that go across the brain, starting at the back and moving slowly towards the front. First there is a wave of excitation, followed by what is called spreading cortical depression. This has been known since the 1940s, when it was discovered in rabbits by a Brazilian neurologist named Leao, although it wasn't immediately associated with migraine at that time. Interestingly, though, there was another neurologist at about that time (named Lashley) who tracked the spread of his own visual auras, and found that they moved at about 2-3 mm/minute. This is about the same speed as spreading cortical depression.

We have since made an association between cortical spreading depression and migraine aura. And, in fact, we have been able to demonstrate very slow changes moving across the brain during migraine aura on both blood oxygen level dependent (BOLD) MRI studies and magnetoencephalography. These changes move at a rate consistent with the speed of cortical spreading depression. Although most of these studies have been done in migraine with aura, there is one PET study done in a single patient who has migraine without aura showing slowing of blood flow in a similar pattern, suggesting that cortical spreading depression may occur in migraine without aura as well. Obviously, it is much harder to study in migraine without aura, as it is more difficult to determine when the beginning of the attack is in order to test it.

There is also evidence of brainstem activation at the beginning of a migraine. Areas of the brainstem show up as brightly active on PET scans in the beginning of a migraine attack. These studies have indicated that brainstem activation occurs in both migraine with and without aura.

Based on research, the best understanding we now have is that migraine arises from abnormally excitable neurons in the brain and trigeminal nerves. What causes the neurons to be abnormally excitable? Various things can do this, including low magnesium, abnormal calcium channels on the surface of the neuron, mitochondrial abnormalities, or other inherited brain chemical abnormalities.

The trigeminal nerves start in the brainstem in the trigeminal nucleus caudalis, and travel to your face, teeth, eyes, sinuses, and forehead. They also go to the blood vessels on the surface of the brain. So, now we have excitable neurons, and dilating blood vessels. These make up what we call the trigeminovascular system, or trigeminovascular theory of migraine.

Once the messages come from the activated cells in the trigeminal nucleus in the brainstem, and travel to the trigeminal nerves that go to the dural blood vessels on the brain's surface, it causes dilation. It also causes the release of brain chemicals called neuropeptides (substance P, CGRP or calcitonin gene-related peptide, neurokinin A, 5HT or serotonin, and noradrenalin.)

The release of these chemicals causes inflammation, and what is called peripheral sensitization. This is most likely what results in the throbbing pain most people experience. As the attack progresses, something can occur called central sensitization. When this occurs, it causes what is known as cutaneous allodynia. This means that things that are usually just a normal touch are now felt as painful. Many headache patients with allodynia cannot continue to wear earrings, necklaces, or their glasses. Some find that they cannot lie down on the side of the head pain, or report that "even their hair hurts." Up to 80% of migraine sufferers are affected by some degree of cutaneous allodynia, and it generally occurs in the late stages of a migraine attack when the pain is severe. This is why it is important to treat early when the pain is mild or moderate.

When central sensitization becomes advanced, it can involve areas beyond the head, and simple touch on the arms or shoulder can be perceived as painful.