In May, we reported that a group of researchers working in conjunction with clinical staff at Sandwell and West Birmingham Hospitals NHS Trust, have designed and built a virtual reality (VR) application for use by the NHS in the treatment of CRPS and painful musculoskeletal conditions.
Now, researchers at Imperial College, London, have published a paper which, while not conclusive, is yet further evidence that immersion in VR may help to trigger the body’s own pain fighting mechanisms.
How does it work?
Distraction-related VR therapy is based on the “gate control” theory of pain, which was developed in the 1960s. According to the theory, pain messages travel from the periphery of the body through nerve “gates” in the spinal cord and up to the brain. The theory uses the idea of gates to describe how some pain messages are allowed to get through and reach the brain, while others are blocked.
It is thought that distraction-related therapies such as VR give the brain an opportunity to send a signal down the spinal cord to close the pain gates before the signal arrives at the brain.
The 2016 study
The results of the first major study into VR were published in 2016. It involved thirty burns patients who used a specially developed VR application. Almost all of them reported a decrease in their level of pain within a session lasting only five minutes. In fact, ten of the participants said that they felt no pain at all during the session!
The study at Imperial College was unusual in that it involved healthy volunteers. In order to induce pain, first capsaicin (the active component of chilli which makes it ‘hot’) was applied topically to one leg in order to make it more sensitive to painful stimuli. Then, a small electric shock was applied to the leg.
Participants were requested to rate their pain from 0 – 100, ie from ‘no sensation’ to ‘worst pain imaginable’, while they were watching either a virtual reality scene or a still image on a screen. Both the VR scene and the still image featured the same theme, the Arctic.
Despite the small number of participants (only 15), the clear result was that both ongoing pain and painful stimuli on the skin were reduced following immersion in VR. The same effect was not produced in people looking at the still image, supporting the theory that immersion is the key factor.
The Cedars-Sinai study
The Imperial study follows the publication in August of a study involving 120 hospital patients at Cedars-Sinai Medical Center in California, who were suffering acute pre and post operative pain. Of those 120 patients, those in the experimental group were provided with “a library of 21 VR experiences administered using the Samsung Gear Oculus headset”.
The researchers’ conclusion was clear:
“VR significantly reduces pain versus an active control condition in hospitalized patients. VR is most effective for severe pain. Future trials should evaluate standardized order sets that interpose VR as an early non-drug option for analgesia.”
Indeed, all of the literature published so far on VR seems supportive of its ability to reduce pain, whether acute or chronic, in a majority of patients. And it is an effect that can actually be seen through imaging. Functional MRI scans (fMRI) have revealed a significant reduction in pain-related brain activity in people while using VR.
Like medication, VR is not a cure, but unlike medication VR has no obvious side effects. While it may not replace medication and other forms of treatment, researchers hope that for many patients suffering both acute and chronic pain, at the very least VR can help them to reduce their medication intake.
The benign nature of VR means that, unlike many new innovations in pain medicine, it is predicted to swiftly join the mainstream treatment arsenal.