Virtual reality (VR) is one of the next hot tickets in pain treatment. A lot of hope has been built into research on the technology over the last decade, after pioneering work showed VR worked as a pain reliever during burns dressing changes, and also altered which parts of the brain were active during a painful procedure.
The nuts and bolts of VR’s use are straightforward. Typically, patients undergoing a “VR intervention” wear a head-mounted display (HMD), through which is streamed 3D content such as videos and games in an immersive virtual environment (VE).
The technology is now cheap – a multitude of research backs its use for a range of pain conditions, albeit with hefty levels of positive bias built in. And it’s not pharmaceutical, which is a critical consideration for US doctors aware of the 70,000 opioid overdose deaths in their country last year.
But it’s not without its Achilles’ heels. Cybersickness – the VR form of motion sickness – is one. Children already familiar with VR technology are another. Well attuned to VR play in their everyday lives, they’ll likely require ever-more engaging and complex VR scenarios to distract them from pain.
If VR is to gain currency as a pain treatment, medical VR filmmakers will need to get more creative, speculates Dr Naseem Ahmadpour, a University of Sydney Human-Computer Interaction (HCI) researcher and lead author of a paper on how to design VR content for pain relief.
“VR technology is increasingly accessible to consumers, who will be less impressed by the novelty of this technology and its power to distract in the near future,” she wrote last year. “We will soon need better design strategies and the ability to predict the outcomes of VR intervention to help individuals with complicated health needs.”
This means digging deep into what VR actually does to the brain – then finding ever more sophisticated ways to trick it into believing that the virtual is real.
How does VR work in the brain?
When it comes to pain, VR works on several levels.
At a neurochemical level, it activates the frontal lobes that deal in memory and belief, triggering neurotransmitters, “some of which are similar or identical to painkilling drugs”, says British health VR company Rescape Innovation.
Companies working in this field are testing content that manipulates which neurotransmitters are released. They don’t want to constantly trigger a dopamine hit, as video games or Facebook do, and thus swap out addictive opioids for a different “drug”, says Dr Robert Louis, a neurosurgeon and VR advocate at Hoag Hospital, in California.
But they do want to power up other chemicals like the different groups of endorphins, which actively moderate pain signals. This is done by evoking positive emotions by, for instance, immersing a person in a beautiful setting or by watching baby animals, a known method to deliver a jolt of the love hormone oxytocin.
However, while pioneers like Louis are working with Hollywood producers to create content that targets specific neurochemicals, reward-based games are an obvious choice for many contexts. SnowWorld has been used for changing of burn dressings; Bear Blast was developed by Applied VR; while XRHealth, which is active in Australia, uses VR games for some physio rehabilitation. These games involve virtual activities such as throwing snowballs and other balls at the likes of penguins and bears.
The other level is distraction.
“If the main object of your focus is pain, you’re thinking about it, you’re worrying about it, you’re wondering what’s going to happen next, you’re building it up in your mind, and you’re activating your sympathetic nervous system response to it,” Louis says. “It’s the fight-or-flight response.
“By contrast, an immersive virtual reality experience that’s designed for this, deactivates the sympathetic nervous system and activates the parasympathetic nervous system – the rest-and-digest-you’re-okay part of the nervous system.”
For acute pain, such as having burn dressings changed (for which pharmaceutical pain relief is limited), distraction works via the “gateway” theory of pain – the idea that the body can only process so many sensory inputs at once. VR engages other senses, such as sight, hearing and touch, to trick the brain into believing that what it’s experiencing is real, and distracts from the pain of the moment.
In Australia, the technology was trialled at Monash Women’s Hospital, Melbourne, in 2019 to distract women from the pain of having a breech baby manually manoeuvred into the correct, head-down, birthing position, and for laparoscopies, or keyhole surgery.
“What we found in the laparoscopy study is that it not only reduced their pain scores, but also reduced the requirement for pain relief, like morphine,” says Dr Vinayek Smith, an obstetrics and gynaecology clinician and researcher at Monash University.
“The morphine requirements within the first half an hour became zero with the use of virtual reality. It’s definitely not something we’ve ever seen before. Pain relief needs vary from person to person, but what we know is that usually in the first two hours post-surgery we see a spike in the amount of pain relief required by women.”
Solving the chronic problem
But distraction doesn’t cut it with chronic pain. Chronic pain can become cognitive and emotional when the messages of pain are no longer just sensory but also factored into the way the brain perceives stimuli, such as specific movements.
It’s here that some cutting-edge Australian research is building on the theories of pain and VR’s impact on brain function.
Dr Sylvia Gustin, a psychologist and neuroscientist, has submitted a paper to the Journal of Pain (yet to be peer-reviewed) that should expand our understanding of chronic pain and how VR affects it.
She works with patients who have spinal cord injury nerve pain, an unremitting pain in a limb that is no longer felt. There’s little pharmacologically on offer to dull that sensation.
The study focused on a subset of patients in a larger trial using virtual reality that simulated the sensation of walking. The idea was that by tricking the brain into believing it was walking, it would stimulate normal brain functions and relieve the pain.
Seven participants were sent into an MRI after being immersed in the VR world. Gustin’s team saw a significant increase in the signalling neurotransmitter GABA in the thalamus – the “boom gate” that moderates sensory messages, like pain, from going into the higher cortexes and delivering messages back to the nervous system.
Spinal cord injury pain is associated with shrinkage in the motor and sensory cortexes. Fewer brain cells mean less GABA is made, which means more signals start getting through the thalamic boom gate. For people with spinal cord injury, a malfunctioning thalamus means their motor cortex is overstimulated, yet because the person can’t walk, it sends back that horrific sensation of pain to the nervous system.
Gustin originally tried to have patients imagine they were walking in order to try to rewire the brain around the parts that were shrinking, with disastrous consequences. The brain knew, of course, that it was simply the imagination at work. The outcome was to hyperstimulate the existing pain pathways.
But then Gustin added VR.
“I believe when you activate the motor cortex in a way which is normal, you’re also activating the thalamus in a healthy and adaptive manner. And that means brain cells start producing GABA in a normal way, so the motor has fuel again and the boom gate can close,” she says.
“You are activating the brain cells in a way so that they can talk to each other normally again, and we are not creating this over-activation. The brain thinks it is really walking, so that means that the activation doesn’t stay only in the motor cortex, it gets forwarded to the thalamus.”
Other types of chronic pain, like neck pain, don’t feature the same kind of neuronal destruction in the cortexes, but the study shows how a VR simulation can begin to rewire the brain.
It’s still early days in the design of the actual content of VR simulations for pain.
“Just being in virtual reality by itself doesn’t have nearly as much of a therapeutic benefit as a specific program designed for pain relief,” Louis says. “If I play a game in VR, I may get some pain relief, but it isn’t the same as a program structured specifically for pain.”
Very little is known about what targeted medical content works, and will continue to work as subjects become more familiar with VR tech. The trick will be building a Netflix-like library of medical simulations that can suit different people and different conditions. Louis wants Moana-like water quality with Disney storytelling.
There are some basic building blocks to a VR that actually work for pain, said Ahmadpour in her paper last year.
Interactive experiences work better than passive ones; familiar computing elements avoid the frustration of trying to learn the nuts and bolts of how to do things in the VR world; the narrative has to invoke emotions; and, most importantly, the subject must have a sense of “presence” in the VR world, created by engaging as many senses as possible.
Different types of pain need different VR simulations, too. Passive distraction might work for one-off acute pain for some people, but people with fears of continual acute pain, such as children living with cancer who must constantly endure needles, may react better to being walked through the process via VR, or given a coping strategy like a breathing game.
At Hoag Hospital in the US, they’ve just finished building a 20-week program for pregnant women that educates them on different aspects of pregnancy, labour and the weeks after birth, but includes modules on dealing with pain.
“We find [for labour pains] it’s not one particular experience but rather the ability to move from one experience to another, which makes a difference,” Louis says. “One of the modules is painting beautiful pots, to give you something to do. But then you can switch to a beautiful scene at a beach.”
It’s another example of VR’s potential to push the boundaries of what we know about pain, and pleasure.