Migraine headaches are not only incredibly common -- about 12% of the world’s population suffers from them -- but they also come with an array of baffling symptoms, including nausea, sensitivity to loud sounds and bright lights, and lightheadedness.
Now, researchers are probing the links between migraine and another ailment: motion sickness. Gabriela Carvalho, a researcher and physiotherapist at the University of Leubeck in Germany, said she was always interested in studying the mechanisms of migraines and related functional impairment precisely because it wasn’t an area that garnered a lot of attention. "Everyone is always interested in the neck and how to treat pain, but we were perceiving that patients with migraine have much more than pain. They have other comorbidities that not a lot of people were paying attention to."
Carvalho has previously studied the balance problems that often affect people with migraine. More recently, she turned her attention to the question of motion sickness. In a paper released today in the journal Neurology, she and her colleagues examined what happened in the brain while migraine patients were going through a dizzying ride.
She used virtual roller coasters to create the conditions for motion sickness. To build the coasters, Carvalho had to learn coding using the No Limits Coaster software program, which uses true gravitational forces to loop, curl and careen participants around virtual coasters for five and a half minutes.
She played the simulations for 20 people with migraines and 20 without while a functional MRI machine scanned their brains. The participants rated their experience of dizziness, vertigo and nausea in a questionnaire. While there were no significant differences in nausea, the migraine sufferers felt more dizziness and vertigo for longer periods of time than people without migraines.
The functional MRI showed that patients with migraine had more activity in a few areas of the brain, including the cerebellum; the occipital lobe, which is the area that processes vision; and the pontine nuclei, which is a small area of the brainstem.
Peter Drummond, a professor of psychology at Murdoch University in Australia, said the new study is a step forward in terms of studying what's happening directly in the brain. "The main conclusions seem to support ideas of what was producing symptoms and why that might be stronger in people who have migraines," said Drummond, who was not involved in the research but has worked on migraine and motion sickness in the past.
Drummond’s work has used visual illusions of movement much simpler than roller coaster simulations to induce motion sickness symptoms. He presented people with stripes moving past, creating the illusion of stripes slowing down or stopping and spinning. He found that the motion sickness symptoms are stronger in people with migraine than in people without migraine -- not only in dizziness and nausea but also in sensitivity to painful stimulation of the head. "So this study is a nice step forward in that now we have some insight into what might be happening in centers in the cerebral cortex, brainstem and cerebellum that might increase susceptibility," Drummond said.
Virtual reality has also been used not just to study migraines, but also to treat them, as in a 2013 study that showed patients a fully immersive VR experience of a waiting room with an ocean view. While patients were gazing at the virtual ocean, they were less sensitive to pain from seeing laser lights.
While it’s still an open question what exactly the bridge is between motion sickness and migraine, Drummond said the evidence from this and past studies hints at some kind of reduction in the inhibitory processes that normally dampen down unpleasant sensations -- from bright lights and noise to head pain and gastrointestinal discomfort, said Drummond. "We don’t actually have our finger on what actually is driving this disruptor in pain modulation," he said. "If we knew what that was, we could think about how to get things back on track."
This type of research could help scientists better understand the full experience of living with migraines, said Carvalho. "It's not enough just having pain, you have to have other symptoms and other things that bothers you in daily life, and these symptoms can happen not just during the attack, but also between the attacks," she said. "This is a condition which impairs the patient during the whole time, not just when they have the attack and they have the pain. So that's why I think it's very important to be understood and treated."
Source: Inside Science
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