For Vince Clark, immediate pain relief for his son came not from brain-stimulating devices, but something more low-tech.
When Vince Clark’s son, Ryan, became sick, he devoted himself to understanding the neuroscience and trying to find effective treatments.
Complex regional pain syndrome (CRPS) doesn’t really involve normal pain networks, but rather enhanced sensory perception. “Just blowing on your skin is excruciatingly painful. That’s what it was like for Ryan,” Clark says. Physical activity became torture. Muscle tremors and spasms, which can happen with CRPS, were also a huge problem. The initial treatment, with a very high dose of an antidepressant drug, made things worse. “For minutes, sometimes hours at a time, he couldn’t breathe easily. It was a parent’s worst nightmare,” Clark says.
Eventually, through a patient support group, Clark made contact with another neuroscientist whose daughter had CRPS. “He came to me and said, I’ve found this thing – it seems crazy – but look what it does. Let’s try to figure out how to understand this.”
This “thing” was an orthotic – a mouthguard, on which patients bite down. There’s evidence that orthotics can relieve pain and ease movement in people with problems affecting the head and neck. It’s so cheap and simple, Clark thought it was at least worth a try with his son. “At one point, Ryan was in the wheelchair and we couldn’t give him drugs, and he was in too much pain to do the physical therapy he needed to do. So we got him to bite down on a simple wooden tongue depressor. That was the first day he walked for almost a month.”
Clark plays me a video of Ryan. He’s leaning heavily on a walking frame, struggling to take a step. Then the tongue depressor goes in, and he bites down on it with his back teeth. Suddenly, he stands, and he can walk with just a single stick. Clark plays me another video. A woman walks awkwardly, bent over, dragging her legs. A car crash years earlier left her ‘seized up’, struggling to move. She bites down on an orthotic – a more stylised version of a bunch of tongue depressors – and she stands straight up and walks. The person recording the video is stunned. “This blows my mind,” he says. “I can’t believe this!” Clark says. “There are people with motor illnesses, Tourette’s, dystonias, tremors where the person can’t open their eyes any more... I can show you videos of patients with all those illnesses and more. If you just put a stack of tongue depressors on their teeth and they bite down, the symptoms of their illness can disappear almost completely.”
Clark is as well aware of the placebo effect as anybody else. But an imaging study, which he has just completed, shows what he calls “pretty significant changes” in brain function as people bite down. The changes are in the cerebellum, a region that plays an important role in controlling movement. Clark thinks that biting down might work by stimulating the trigeminal nerve, a thick nerve that connects to the central nervous system. “Historically, before anaesthesia, when doctors did surgery, they let a patient bite down on something. The modern assumption is that this was so you don’t grate your teeth and break them. But why do people grate their teeth when they’re in pain?”
Clark is well aware that much more work is needed on a possible role for orthotics in helping with pain and movement disorders. But orthotics, like transcranial direct-current stimulation (tDCS) – which is showing great promise in preliminary trials for treating pain – are of no interest to pharmaceutical companies. And there’s a mindset in the USA, at least, Clark argues, that makes it hard to drum up support for funding trials of cheap, simple devices like this. “We’ve come to believe that more complicated technology is always better. I think that’s a fallacy. It’s not always better. It’s certainly almost always more expensive. You look at these images of patients getting better with an orthotic. If this was after brain surgery or a new drug, people would be swarming to learn how to do it. We don’t have doctors lining up.” In the USA, he argues, on the whole, doctors look for more expensive treatments, because they can make more money from them.
Clark would love to see funding for big randomised controlled trials of simple, cheap devices, like orthotics, or even coloured lenses for kids with developmental disabilities, which were adopted in the California school system after pressure from parents but which have not been well-evaluated. Given the growing evidence for the effectiveness and safety of tDCS, the case for expensive, gold-standard trials in this area is perhaps even stronger. “On average drug companies spend five billion dollars for every new drug that comes to market. A lot of that is on failed drugs,” says Clark. “If you spent five billion dollars on tDCS, you would, I suspect, get the same benefit as developing 100 new drugs – it looks like it could be applied so many different ways.” He urges the US National Institutes of Health to fund the necessary work.