Precisely why CSD begins, no person is aware of. Equally, loads of mysteries stay about what prompts the ache of migraines. Previous research have proposed that migraine complications happen when one thing within the cerebrospinal fluid not directly prompts nerves within the close by meninges, the layers of membrane between the mind and the cranium. Rasmussen’s experiment, led by neuroscientist Maiken Nedergaard, initially got down to discover proof to help this—however they got here away empty-handed. “We didn’t get something,” he says.
In order that they tried a distinct method, injecting fluorescent tracer substances into the cerebrospinal fluid and imaging the mice’s skulls. The tracers concentrated on the finish of the trigeminal nerve, “these huge nerve bundles that lie like two sausages on the bottom of the cranium.” It was a giant shock, he says, to search out substances had been capable of attain this a part of the peripheral nervous system, the place they may activate ache receptors. “So we acquired excited and likewise very puzzled—like, how does it even get there?” This led them to the opening—the tip of the trigeminal nerve that was in open contact with the cerebrospinal fluid.
The researchers additionally sampled the cerebrospinal fluid and located greater than 100 proteins that rose or fell within the aftermath of CSD, suggesting potential involvement within the ache of migraine. A dozen of the proteins that elevated are identified to behave as transmitter substances able to activating sensory nerves, together with one known as calcitonin gene-related peptide (CGRP), a identified goal for migraine medication. Rasmussen says it was signal to search out it among the many combine. “However for us, what’s most attention-grabbing is de facto the 11 different proteins that haven’t been described earlier than,” he says—as these might open the door for brand new remedies.
There are nonetheless causes to be cautious, says Turgay Dalkara, a professor of neurology at Hacettepe College in Turkey with an curiosity in auras. Mouse fashions are helpful, however the dimension variations in rodent and human skulls are problematic—particularly on the subject of the realm the place the opening was discovered. “From the mouse to the human, the surface-volume ratio is dramatically completely different,” he says. The concept Rasmussen’s staff initially investigated—that CSD releases substances that activate and sensitize nerves within the meninges—stays the very best supported mechanism noticed in people, he provides. Rasmussen’s discovering, of this beforehand undiscovered spot the place cerebrospinal fluid might contact nerves, must be thought-about a potential addition to this image, not a substitute for it.
Hadjikhani agrees however is however excited to discover a additional pathway for investigation. For docs, the lack of information about how migraines work means sleuthing for the fitting mixtures of medicines to present victims some reduction. “You strive one. You strive a mix. You are taking one off,” she says. “It’s important to be Sherlock Holmes, discovering what triggers issues.”
The truth that migraines differ a lot means there might by no means be a silver bullet resolution. Rasmussen hopes that, in the long run, having the ability to observe modifications in a person’s cerebrospinal fluid might reduce this guesswork and result in customized options.