A model-based approach for assessing parkinsonian gait and effects of levodopa and deep brain stimulation

Gait and balance disturbances are amongst the most disabling features of Parkinson's disease (PD), and are not adequately controlled with currently available medical and surgical therapies. Development of objective quantitative measures of these abnormalities would greatly help in the assessment and the development of therapeutic interventions. Recently, we developed a methodology, using dynamical system theory, for testing gait with a state-of-the-art motion-detection system (OPTOTRAK 3020, Northern Digital, Inc.). We also developed a model of the dynamics of the foot that predicts the stance and swing phase dynamics of normal walking. In the present study, we determined whether model parameters were altered in subjects with PD when they were tested on/off levodopa (LD) and on/off deep brain stimulation (DBS) in a 2 x 2 matrix.