The effects of asymmetric tonic neck reflex during reaching movement following stroke: preliminary results

Previous studies and clinical observations reveal that stroke survivors show the resurgence of the asymmetric tonic neck reflex (ATNR) both in static and dynamic conditions during maximal efforts. This observation may imply more reliance on the brainstem pathways following stroke. However, the effect of ATNR during a dynamic condition that represents more natural movement, such as reaching, has not been studied before. During reaching movements, the application of a robot controlled haptic environment is important to quantify the effect of ATNR following stroke. Therefore, this paper reports the use of a novel setup using the ACT(3D) robotic device to investigate and quantify this reflexive behavior. Our preliminary results demonstrate that the effect of ATNR is significant in the stroke population when abducting the shoulder at 25% of maximum ability. These results show that the ATNR affects reaching distance especially when shoulder loading in abduction is required. In conclusion, these preliminary results provide evidence that the effect of ATNR in stroke subjects during reaching task can be quantified by using a novel 3-D robotic setup.