Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: thedoc on 13/01/2010 16:14:21
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Scientists have discovered why light makes migraines worse, and the key to the breakthrough was the observation that some blind people also get relief by retreating to somewhere dark.
Rodrigo Noseda and his colleagues at the Beth Israel Deaconess Medical Centre in the US began by asking 20 blind people with migraines whether they experienced light-sensitivity or photophobia when they had headaches.
Surprisingly, some of them did and these were individuals who had sight-loss conditions like retinitis pigmentosa where the light-sensitive rods and cones degenerate, causing visual loss, but the rest of the retina remains healthy. On the other hand, people who were blind owing to congenital absence of their eyes or destruction or removal of the eyes didn’t show this light sensitivity.
This suggested to the researchers that signals arising from the retina must be responsible. To find out how, they used dyes injected into rats to label the nerve cells that connect the retina to the rest of the brain.
They found a group of cells that connect to a region called the posterior thalamus. [img float=right]http://www.thenakedscientists.com/forum/copies/RTEmagicC_nerve_cell_06.jpg.jpg[/img]These nerve cells don’t carry visual information but instead arise from a special group of retinal cells used by the brain to tell when it is like or dark in order to set the body clock.
But, the team found, the cells in the thalamus to which these nerves were connecting were also activated by pain nerves supplying the meninges, the layers that surround the brain and spinal cord and which are thought to become irritated during migraines and infections like meningitis.
So, by activating the same brain cells as the pain pathway, the light-signalling nerves boost the perception of pain.
Clinically, say the scientists, who have published the work in the journal Nature Neuroscience, this sets the stage for identifying new ways to block the pathway responsible, making migraines slightly less of a headache to endure...
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Actually, my migraines are so horrible that when the nurses at the ER asked me if I wanted the light off, I couldn't even reply. The light is only one aspect. I did not think I had auras either but it could be that the 'push' I experience is an aura. Discover magazine back in 2010 had great article on migraines, explored connection to Maxalt the triptans, as to why they work--they don't know. The triptans were used for epilepsy originally. Off label for migraines. Lucky for me rizatriptan works. Did you know that doctors used an amino acid? pre pharma of course.
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I think they might be up the proverbial gum tree with that one.
I have found that by eliminating as many input sources to my brain (visual, auditory, tactile) at the very first sign of a migraine, I can significantly diminish the unpleasant effects. The more I try to fight it, the worse the effects are.
This leads me to believe that migraines might be the result of some sort of (for want of a better term) cerebral positive feedback. We all know how positive feedback works with amplifiers and microphones. That's when the output of the amp produces a very nasty noise because it is amplifying the signal that it is producing.
Amplifiers operate on the basis of gain (the amount a signal is amplified). Guess what? So do brains, except that brains are infinitely more complex than a simple amplifier, so the fix is not quite as simple as putting your hand over the mike, but, in my experience at least, if you can shut off as many inputs as possible in the shortest possible time, you will recover a lot more quickly.