Under the Microscope/Prof William Reville: Many readers will have seen the excellent film The Matrix which is all about a world of virtual reality.
The technology behind virtual reality is under rapid development. It is targeted mainly at the entertainment market but it also has many other applications. Some highly useful applications are in the treatment of severe pain, various kinds of phobias and post traumatic stress disorder. These therapies are described by H.G. Hoffman in Scientific American, August, 2004.
In order to feel pain you must pay attention to it. We have all heard of cases like the rugby player who broke a bone during a match, played the rest of the match and only discovered his injury when the excitement of the match was over. Then the pain began. The simple basis for treatment of pain using virtual reality is mental distraction. You cannot simultaneously entertain two thoughts in your mind. If virtual reality takes over your mind, your brain is not available to process pain signals.
Skin burn is very painful. Severe burns are treated by replacing the damaged skin with skin grafts. These grafts require prolonged medical maintenance and the on-going treatments are severely painful. Patients are routinely administered opiates to dull the pain, but sometimes this is not very effective. Thankfully, recent studies show that virtual reality significantly reduces the pain of burn treatments.
To enter the world of virtual reality the patient wears a stereoscopic, position tracking headset through which he sees 3-dimensional computer graphics, and he negotiates his way through this graphical world. Recently a special programme called "Snow World" was created to assist burn patients during wound care. The patient has the illusion of soaring through an icy canyon, with a freezing river and waterfall, as snowflakes drift down. The icy landscape induces cool feelings that oppose burning sensations. The patient throws snowballs at snowmen, robots, igloos and penguins standing below and hits are visually recorded.
Burn patients report that the pain recorded under opiate administration is much more severe than the pain they feel when virtual reality treatment is added. This result relies on subjective evaluation of pain. In order to check this effect objectively, studies measured pain-related brain activity using functional magnetic resonance imaging (FMRI).
FMRI scans produce images of optical slices through the brain that highlight the chemical activity going on. Healthy volunteers had a brain scan while receiving pain stimulation through a heated element applied to the foot. They reported severe pain and their FMRI scans showed a large increase in activity in regions of the brain involved in the perception of pain. When the volunteers watched "Snow World" during the pain-inducing stimulus they reported big reductions in subjective pain ratings and the pain-related brain activity decreased significantly in the FMRI scans.
Another successful application of virtual reality therapy is the treatment of various phobias by exposing patients to simulations of their greatest fears. This therapy is used to treat fear of heights, fear of spiders, fear of flying, fear of public speaking, and post-traumatic stress disorder.
Hoffman describes a dramatically successful case of treating spider-phobia. The patient had suffered from this disorder for nearly 20 years and had developed obsessive-compulsive behaviours. For example, every night she sealed all her bedroom windows with tape after searching the bedroom for spiders. She became hesitant to leave home.
Virtual reality treatment of phobia gradually introduces the patient to the feared situation. The fear gradually decreases and the patient becomes more comfortable. In the first sessions, the patient sees a virtual tarantula in a kitchen and approaches as close as possible using a hand-held joystick to move through the 3-D scene. The goal is to come within an arm's reach of the spider.
In the final sessions tactile feedback is added. A furry spider is suspended before the patient allowing him/her to feel the spider while touching the virtual cyber spider with the virtual hand. After 10 one-hour sessions, the patient showed dramatic improvement. She could hold a live tarantula for several minutes with little anxiety and her obsessive-compulsive behaviours disappeared.
Virtual reality therapy is now used to treat post-traumatic stress disorder (PTSD). PTSD symptoms include flashbacks, intense reactions to memories of the event, emotional numbing and irritability. This debilitating disorder affects social life and job performance, and is much more difficult to treat than specific phobias. Hoffman describes treating a young woman who witnessed the September 11th attacks on the World Trade Centre.
Virtual-reality therapy is in its infancy. It appears to be effective in treating burn-pain but large clinical trials will be needed to say for certain how effective this therapy is. Much research must also be done to determine whether virtual reality can enhance treatment of PTSD. However, there is good reason to think that virtual-reality therapy will be very effective in many areas.
William Reville is associate professor of biochemistry and director of microscopy at University College Cork