The applications of virtual reality (VR) range from enhanced gaming experience to improved retail and medical training to a weight loss solution. Scientists take VR even further proposing treatments to conditions like depression, post-traumatic stress disorder, and pain management, with the latter potentially tapping into a $36.1 billion global pain management market.
Current acute and chronic pain treatments include opioid-based drugs which are responsible for increased risk of addiction and misuse. In 2015, addiction to opioids related to prescription pain relievers caused 20,101 deaths in the USA and four in five heroin users reportedly started out from misusing prescription drugs. As scientists look for safe alternatives to opioids in the face of a growing epidemic, VR presents itself as an intriguing alternative.
Virtual reality provides distraction from feeling pain
The ability of VR to reduce pain has been attributed to distraction. While experiencing pain requires conscious attention, VR distracts from pain perception through submerging the patient into a virtual world.
Studies attempting to prove the effectiveness of VR in distraction from pain suggest VR decreases pain perception and increases tolerance to pain.
VR and burn wound patients:
In a study conducted by Jeffs et al., patients suffering from painful burn wounds were put in three different situations:
1. One group was exposed to immersive VR
2. Another group was provided a passive distraction like watching a movie
3. The last group was treated according to the standard of care.
The results: The VR experience that included interactive play in the snow and throwing snow balls resulted in decrease in pain and greater distraction than in case of passive distraction and standard care.
VR and pain tolerance:
Similarly, Law et al. applied passive and interactive distraction using a Nintendo Wii™ video game. The game used as the distraction stimulus was the “Aqua Garden” level of the “Nights: Journey of Dreams”™ video game. The passive group could not control the game while the interactive group had control over events in the game. The pain tolerance was measured by how long the study participants could keep their hand in cold water.
The results: Both distraction groups showed increase in pain tolerance from the baseline but interactive distraction was more effective than passive distraction.
Are there any other mechanisms besides distraction?
Several studies support the notion that neurophysiologic mechanisms other than distraction mediate the effect of virtual reality on pain.
VR and pain threshold:
In a study conducted by Loreto-Quijada et al., the VR distraction group (through an interactive virtual environment) were compared to a VR group where patients had the ability to modify their pain perception by manipulating a sharp object representing pain into a smooth object representing lack of pain.
The results:
- The VR distraction group had an increased pain threshold and tolerance compared to the control group.
- The VR group with the ability to manipulate a sharp object showed increased pain tolerance compared to the control group.
- An increased perceived ability to control pain and decreased helplessness were observed in the VR group with ability to manipulate a sharp object, while for the VR distraction group there were no differences in those metrics.
These results suggest that VR can influence pain by mechanisms other than distraction including modification of the perceived ability to control pain and modification of negative thoughts related to pain.
VR and migraines:
Shiri et al. studied the effect of virtual reality on migraine patients. Subjects were told to relax during an attack. Readings of increased conductance of the skin due to sweating (Galvanic Skin Response – GSR) was used to measure headache related pain.
The results: Successful relaxation, according to the GSR, was coupled to a calmer and happier facial expression seen in VR leading to further relaxation. Long term improvement in daily functioning of subjects was observed after therapy and some patients reported events where they could relax during a headache to a point where the pain disappeared. The long-term effect of the therapy suggests involvement of a mechanism other than distraction.
Can we expect effective, opioid-free treatments soon?
So far, the mechanism of action of virtual reality on pain perception apart from distraction are still being investigated and larger studies are necessary to understand the way VR impacts the feeling of pain.
Since most of the studies were limited to a small number of subjects, had unequal ratios of women and men, and were subject to other experimental limitations, more investigation is necessary to improve the proposed treatment strategies. One of the directions the research is taking is improving the immersive experience and therefore the presence in the virtual world through increasing the quality of the VR system and the addition of sounds. Regardless of the limited data on the mechanism of action of VR, the effectiveness of treatments through distraction has been shown and VR earns a place as one of the possible candidates for pain management alternatives. However, we might have to wait a little longer for standardized therapeutic regiments involving virtual reality.
