The Turning and Barrier Course: a standardized tool for identifying freezing of gait and demonstrating the efficacy of deep brain stimulation

Freezing of gait (FOG) is a devastating axial motor symptom in Parkinson9s disease leading to falls, decreased mobility and quality of life. Reliably eliciting FOG and quantifying impaired gait has been difficult in the clinic and laboratory, and have prevented elucidation of underlying neurobiomechanical mechanisms, making this symptom one of the unsolved challenges in the treatment of Parkinson9s disease. The efficacy of treating FOG with different frequencies of subthalamic deep brain stimulation (STN DBS) is unclear, and this may be due to the variety of methodologies used to assess FOG. In this study we validated an instrumented gait task, the turning and barrier course (TBC) with the international standard FOG questionnaire (FOG-Q, r = 0.74, p