The volume of the pain is hard for Randy McAllister to describe.

"You get to the threshold where you can't stand it, then find out it can hurt a lot more," says the 60-year-old farmer from The Dalles. He was severely burned while trying to save equipment from a fire in wheat field in August.

During five weeks at the Oregon Burn Center at Legacy Emanuel Medical Center in Portland, McAllister needed repeated rounds of wound care to remove dead tissue from his extensive burns.

"It's just the most painful thing," he says. "More painful than the fire."

He was ready to try anything when a nurse told him about SnowWorld, a computer game designed to help burn patients escape from agonizing pain. During his next wound care session, McAllister wore headphones and looked through virtual reality goggles. He found himself floating through an icy canyon rendered almost three-dimensional by the wrap-around goggles. By tapping on a computer mouse, McAllister fired snowballs at animated penguins, snowmen and dolphins in the canyon to a soundtrack of upbeat Paul Simon songs.

Strangest of all, the virtual world made his real world pain less overwhelming.

It's one of the most successful examples of non-drug pain management techniques to emerge from the work of psychologists and neuroscientists. The search for non-drug options has gained urgency amid a worsening epidemic of overdoses linked to prescription opioid pain relievers such as oxycodone and hydrocodone, which killed 14,800 Americans in 2008 – more those killed from heroin and cocaine overdoses combined.

In clinical trials, burn patients using

reported 35 to 50 percent

. The system was developed at the University of Washington by research scientist Hunter Hoffman and psychologist David Patterson, with input from burn care experts at Harborview Burn Center in Seattle.

Virtual reality therapy isn't a substitute for opioids and other pain-relieving medications, but it can boost the effectiveness of drugs – and possibly reduce the dosage. Researchers who developed the technology say it may also help people with chronic pain syndromes, although those clinical trials are incomplete.

Theresa McSherry, burn and wound care coordinator at the

, says burn patients desperately need more options. Pharmaceutical research has provided safer and more effective anesthetics and opioid pain relievers, but drugs have limits.

"You just can't safely give burn patients enough to provide adequate pain relief," says McSherry, a registered nurse who has worked with burn patients for more than 10 years. A grant from the Legacy Foundation allowed the Oregon Burn Center to buy the $66,000 virtual reality system in August. About a dozen are being used worldwide.

Preventing pain not only relieves immediate suffering, but also seems to help burn patients weeks and months later. Patterson, the UW psychologist, says the amount of pain during treatment is a stronger predictor of depression, anxiety and distress six months to a year later than the extent of burns or the length of hospital stay.

"If you can control more of the acute pain, it can result in better long-term outcomes," he says.

Scientists have known for decades that the human brain can interpret the same signal transmitted by a pain receptor as painful or not, depending on what a person is thinking. During World War II, a physician named Henry Beecher observed that soldiers seldom required morphine

. Civilian patients with comparable wounds were much more likely to require morphine. Beecher concluded that there was no direct relationship between the severity of the wound and the intensity of pain. He was among the first to propose that the meaning our minds give to an injury greatly determines the level of pain. For soldiers, he theorized, the wound meant surviving combat and returning home.

Mood and expectation also play a big role. German researchers

that a sad mood consistently makes people experience more pain. In another

, tricking people to think time passed more quickly reduced perception of pain

Hoffman reasoned that entering a rich, three-dimensional and sound-filled virtual reality could command so much of the brain's attention resources that less would be available to process pain.

"We're taking advantage of the malleability of human perception to deliberately divert mental resources away from the pain," he says.

Pain by association

Burn patients come to associate the sights and sounds of the wound treatment room with excruciating pain so that just entering the room can amplify the suffering, Hoffman says. Putting on headphones and goggles blocks the anxiety-stirring sights and sounds.

But distraction of attention appears to be the main way that virtual reality reduces pain. Hoffman's team has compared differing gear and found that the more realistic and "immersive" the gear, the greater the reduction in pain reported.

That matches McAllister's experience. His burned fingers made it difficult to hold the computer mouse during his SnowWorld experience. When the mouse slipped from his hand and he lost engagement with the snowball throwing, the pain of the procedure immediately intruded.

"Oh boy, yeah," he says. "Absolutely." McAllister expects to continue intensive physical therapy for several months to regain more use of his fingers and hands. He may need additional surgery to remove scar tissue and increase joint mobility. But he's optimistic about returning to work next year.

Patterson believes virtual reality can help treat chronic pain, too. The UW researchers also developed a virtual reality program that induces hypnosis. The goal is to use post-hypnotic suggestion to change the way the brain handles chronic pain signals long after therapy sessions.

In the virtual world, subjects descend through the air, viewing a series of numbers, until they find themselves floating over a lake in a hypnotic state. Some people are resistant to hypnosis, and Patterson speculates that virtual reality systems may help overcome that resistance. Use of virtual reality could make hypnosis more standardized and accessible, he says.

"Chronic pain is a much bigger challenge than acute pain," Patterson says. His group has received a grant from the National Institutes of Health for a controlled clinical trial of virtual reality hypnosis for chronic pain.

--