Kinematic Characteristics of Athetoid Movement During Target Acquisition

Sara Sibenaller1,4 , Dan Ding, PhD.1,4 , Brad Dicianno, M.D.2,4 , Rory A. Cooper, PhD.1,4 , Cameron Riviere, PhD.3
1 Dept. of Rehab. Science & Technology, University of Pittsburgh, Pittsburgh, PA 15261
2 Dept. PM&R, University of Pittsburgh Medical Center, PA 15213
3 The Robotics Institute, Carnegie Mellon, 5000 Forbes Avenue, Pittsburgh, PA 15213
4 Human Engineering Research Laboratories, Highland Drive VA Medical Center, Pittsburgh, PA 15260


Athetosis is a complex movement disorder characterized by writhing movements mainly in the upper extremities.  It is seen in approximately 10-20% of people with Cerebral Palsy (CP) and can greatly hinder the use of assistive technologies such as computers, electric powered wheelchairs, and environmental control units.   In this study, an isometric joystick developed at the Human Engineering Research Laboratories was interfaced with a laptop computer to collect movement from seven people with athetoid CP and one able bodied participant for comparison purposes during a target acquisition task. The athetoid movement was quantified using kinematic and performance variables which helped to identify potentially beneficial real time filter inputs that could be used to modify athetoid movement.  The results show a strong negative correlation between average peak acceleration and index of performance (p=0.036 R2=0.617), a strong positive correlation between average speed and percent distance error (p=0.014 R2=0.734), and a strong positive correlation between combined Modified Ashworth Score and percent distance error (p=0.032 R2=0.797).  The results of this study will contribute to a better understanding of athetoid movement and help to focus filter development efforts in order to create appropriate computer interfaces and power wheelchair controllers that correct unintentional movement thus helping to increase independence in people with athetoid CP. 


Computer Access; Wheelchair; Cerebral Palsy; Isometric Joystick; Athetosis


This research is supported by the United States National Institutes of Health Grant R21 HD050717. 


Sara Sibenaller, Human Engineering Research Laboratories, VA Pittsburgh Healthcare System, Pittsburgh, PA 15206, Phone: (412) 365- 4945, Fax: (412) 365-4858,