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Years after people lose arms or legs to wartime injuries or in car accidents, they can still feel them hurt or tingle. Doctors don't fully understand this "phantom limb pain," but researchers at the Minneapolis Veterans Medical Center are determined to improve treatment.

Occupational therapist Tonya Rich said as many as 80% of patients experience the pain after amputations necessitated by traumatic injuries or vascular diseases.

"It's a very real pain that can very much ... impact their day-to-day life," she said.

Solutions unveiled Wednesday as part of the medical center's research week included a mobile at-home therapy app and a brain imaging study to discover the origins of phantom pain. Results of a survey of 50 veterans also showed the challenges ahead because the duration, intensity and type of pain varied substantially.

"It's like if you walked to a concrete wall and took your shoe off and kicked it as hard as you can. Over and over and over again," one veteran told interviewers.

Another likened the condition to "pouring soda into a glass and watching it fizz. It goes all the way down to the toes. It starts at the lower end of the stump and goes to the toes that aren't there."

Experts disagree on the roots of the disorder and whether they are physical, mental or some combination of the two. The Minneapolis medical center conducted MRI scans of veterans with phantom limb pain to look for distinct features in their brains. Results will soon be published.

"We don't have this mechanism question answered," Rich said. "So this is just to help explore and say, 'OK, can we help put some of the pieces of this together?' Because the theories [on the origins of phantom limb pain] just butt heads all the time."

Beyond prescription medications, doctors have performed surgeries to address the severed nerves that are likely contributing to phantom pain. Connecting them to healthy nerves or muscles appears to give them something to do other than send false pain signals.

Rich said therapeutic alternatives are needed because some patients aren't candidates for surgeries. The 50 veterans in her survey tried everything from hot and cold compresses to meditation, marijuana and acupuncture.

Sixteen who only lost limbs on one side of their bodies tried mirror therapy. The approach creates visual illusions with mirrors to trick patients' brains into thinking they have two limbs that are intact and pain-free.

Rich said she has had success with that approach, and that the medical center's Minneapolis Adaptive Design & Engineering program is developing an app and online tools to help veterans do mirror therapy at home.

One idea is an "augmented reality" app that allows patients to do mirror therapy by sitting and holding video tablets over their legs. The camera on the tablets creates duplicate images and makes it appear as if both legs are intact.

Figuring out who needs which treatment is another challenge. Researchers plan to monitor 15 veterans for 40 days this summer to see what triggers their phantom pains and whether that suggests a personalized course of treatment.

After an explosion in Iraq cost John Kriesel parts of both legs in 2006, the Minnesota National Guard member said that for a year or two afterward, phantom pain felt as if he were being jabbed with razor blades.

Mirror therapy wasn't an option for Kriesel, but he said he learned a mental trick from a Vietnam veteran to imagine that his feet were unnaturally rotating 360 degrees. Along with medication early on, the imagery helped for some reason.

Today, Kriesel, a former member of the Minnesota House, said he only experiences phantom pain once or twice a month. But he said it can still be severe, especially at night. He's never sure why it emerges.

"I do get phantom sensations," Kriesel said. "Like right now, if I talk about my toes, I can kind of feel my toes like I'm wiggling them. Phantom sensation is fine. It helps you know where your feet would be when it comes to walking and stuff. That doesn't bother me. It's the phantom pain that sucks."