Moreover, the robotic therapy - which involves a more intense regimen of activity than traditional stroke therapy - did not increase the total health care costs per stroke patient, and could make intensive therapy available to more people, according to the researchers who led the study.
Hermano Igo Krebs, a principal research scientist in MIT's Department of Mechanical Engineering, started developing the robotic system, dubbed MIT-Manus, more than 20 years ago. The system is based on the principle that stroke patients benefit the most when they have to make a conscious effort during physical therapy. The patient grasps a robotic joystick that guides the patient's arm, wrist or hand as he or she tries to make specific movements, helping the brain form new connections that will eventually help the patient re-learn to move the limb on his or her own.
In the New England Journal of Medicine study, researchers at four Veterans Affairs (VA) hospitals - in Baltimore, Seattle, West Haven, Connecticut, and Gainesville, Florida - compared the MIT-Manus system to a high-intensity rehab programme delivered by a human therapist, which was designed specifically for this study.
Each group included about 50 patients, who were also compared with a group of 28 stroke patients who received so-called "usual care" - general health care and three hours per week of traditional physical therapy for their stroke-damaged limb.
Patients using the MIT-Manus system grasp a joystick-like handle connected to a computer monitor that displays tasks similar to those in simple video games. In a typical task, the subject attempts to move the robot handle toward a moving or stationary target shown on the computer monitor. If the person starts moving in the wrong direction or does not move, the robotic arm gently nudges his or her arm in the right direction. "The ability to be interactive is critical", stated Hermano Igo Krebs. "We program the robot to only give assistance as needed."
Patients in the study received therapy three times a week for 12 weeks, and during each hour-long session, they made hundreds of repetitive motions with their arms. At the end of 12 weeks, tests revealed a small but statistically significant improvement in quality of life, and a modest improvement in arm function. When the subjects were tested again at 36 weeks, both the robot therapy group and intensive human-assisted therapy group showed improvement in arm movement and strength, everyday function and quality of life compared to the usual care group.
The high-intensity interactive physical therapy offered to patients who did not receive robot-assisted therapy was developed specifically for comparison purposes for this study, and is not generally available. Furthermore, the physical demands on the therapist make it unlikely that it will ever be widely used.
"If you can get a therapist to work at that pace with a patient, certainly the benefits are roughly the same, and we showed this benefit when we designed this intensive comparison group, but it's not practical", stated Hermano Igo Krebs. "Robotics and automation technology are ideal for this kind of highly repetitive tasks. We're using robotic technology to create a tool for the therapist to afford this kind of high intensity therapy while maintaining the therapist supervisory role, deciding what is right for a particular patient."
Hermano Igo Krebs believes that once the robotic devices can be mass-produced, which he expects will occur within the next 10 years, the costs will drop enough that their use could become widespread. "What you have to do is make more of them, and that will drive down costs to a point where people can have them in their homes", he stated.
Hermano Igo Krebs is now working with doctors to plan a study of patients with less severe impairments, who have had their strokes more recently. He believes those patients may show even more improvement with robotic therapy. He and his collaborators are also studying whether the MIT-Manus could help patients with cerebral palsy, multiple sclerosis and spinal cord injury.
The study "Robot-Assisted Therapy for Long-Term Upper-Limb Impairment after Stroke" appears in the New England Journal of Medicine. The authors are Albert Lo, Peter Guarino, Lorie Richards, Jodie Haselkorn, George Wittenberg, Daniel Federman, Robert Ringer, Todd Wagner, Hermano Igo Krebs, Bruce Volpe, Christopher Bever, Dawn Bravata, Pamela Duncan, Barbara Corn, Alysia Maffucci, Stephen Nadeau, Susan Conroy, Janet Powell, Grant Huang and Peter Peduzzi. Funding has been granted by the Veterans Affairs Cooperative Studies Programme and Rehabilitation Research and Development Service.