Some 50,000 people in the U.S. are diagnosed with Parkinson’s disease (PD) every year. The American Institute of Neurology estimates there are one million people affected with this neurodegenerative disorder, with 60 years as average age of onset. Falls and fall-related injuries are a major issue for people with Parkinson’s. Up to 70% of advanced PD patients fall at least once a year and two-thirds suffer recurring falls. These fall rates are twice as high as those of adults of comparable age, so improving balance in patients with Parkinson’s would provide a major health advantage.
Sunil Agrawal, professor of mechanical engineering and of rehabilitation and regenerative medicine at Columbia Engineering, along with Dario Martelli, a post-doctoral researcher in his group, have been working on this issue with Movement Disorders faculty from the department of neurology at Columbia University Medical Center, Stanley Fahn, a leading expert in Parkinson’s, and Un Jung Kang, division director, and Movement Disorder Fellow Lan Luo. In their latest study, published Dec. 19 in Scientific Reports, the team looked at whether or not Parkinson’s disease affects patients’ balance and diminishes their ability to react and adapt to walking with perturbations. The researchers found that the ability to adapt to multiple perturbations or to modify responses to changing amplitudes or directions was not affected by PD; both the Parkinson’s and the healthy subjects controlled their reactive strategies in the same way. In fact, both groups improved their unperturbed walking after a single training session with repeated waist pull perturbations.
Agrawal’s team, experts in rehabilitation robotics, used a robotic system—Tethered Pelvic Assist Device (TPAD)—invented in his Robotics and Rehabilitation (ROAR) Laboratory to perform the study. The TPAD is a wearable, lightweight cable-driven robot that can be programmed to provide forces on the pelvis in a desired direction as a subject walks on a treadmill. In an earlier study, Agrawal successfully used the TPAD to improve posture and walking in children with cerebral palsy.
Nine PD patients and nine age-matched control subjects participated in the study. The researchers evaluated the margin of stability and base of support while the study participants walked without cables on a treadmill. Then the participants were hooked up to the TPAD’s cables and given waist-pull diagonal perturbations for brief periods to assess their reactions. Each group was then trained with 72 randomly applied pelvic force perturbations that varied in direction (forward/backward/sideways), intensity (low/medium/high), and the specific foot (right/left) in contact with the ground. After this training period, they walked freely without the cables and underwent the same diagonal perturbations they had been given before training. These post-sessions were conducted to assess the effects of training on their balance and stability.
The team found that the Parkinson’s patients had a reduced stability in the forward direction before and after training compared to the healthy subjects and an inability to produce proactive anticipatory adjustments. Once all the subjects completed the training session, both groups were able not only to improve their response to the perturbations, but also to produce short-term aftereffects of increased gait stability.