Motor control investigation of dystonic cerebral palsy: A pilot study of passive knee trajectory.

The purpose of this study is to better understand dystonia in CP and be able to objectively distinguish between individuals who experience spasticity, dystonia, or a combination of these conditions while evaluating the effect of 2Hz vestibular stimulation. Selected outcome measures included knee ROM, angular velocity and acceleration and all measures increased post vestibular stimulation; these results are indications of a possible reduction in the level of disability. The current investigation also identified an unexpected and unique behavior of the knee in children with dystonic cerebral palsy (CP) that was noticed while administering the Pendulum Knee Drop test (PKD) at approximately 0.4 rad (a mid-angle between full extension and zero vertical). There was a catch-like phenomenon at the described mid-angle in dystonic individuals. These results may suggest that dystonia is not a velocity dependent hypersensitivity of reflexes, but may include position dependent muscle reflexes and co-contractions. This reinforces the need for a more precise objective measure or perhaps a modified measure such as a mid-angle PKD test. Furthermore, based on the results obtained through the modified technique, beneficial alterations can be made to the form of treatment such as: robotic therapy or physical therapy that specifically accommodates the unique motor control disorder in individuals with dystonic CP.