Hand exoskeleton robot for assessing hand and finger motor impairment after stroke

Abstract

This study aims to understand post-stroke hand impairment using a hand exoskeleton robot and explore the possibility of using the device as a continuous monitoring tool to complement the currently used clinical scores. Six right-handed, right-side hemiplegic stroke survivors (55.8 ± 16.6 years old) and six age-matched neurologically-intact control subjects (55.3 ± 18.4 years old) were recruited. Each subject performed two repetitions of isometric flexion and extension maximum voluntary torques (MVTs) on each finger individually and all five fingers together in a randomised order. All joint moments were recorded. A finger individuation index (FI) was derived from the joint moments data. Correlation between the average of the FIs, namely FII, and the clinical scores was then evaluated. The results suggest that stroke subjects produce significantly lower joint moments, about one third of that of the control subjects. Significant differences in FIs were found on all fingers except the thumb, with those of the control subjects ranging from 0.5 to 0.7 compared to the 0.2 to 0.4 of the stroke subjects. FII values were found to correlate well with different clinical scores. Stroke survivors were found to be restricted by lack of both strength and individuality in their fingers. Additionally, FII could potentially serve as a continuous monitoring system of finger individuation.

Keywords:

• stroke
• impairment index
• exoskeleton
• robot
• rehabilitation

Disclosure

Ir Prof Raymond K.Y. Tong and Mr Newmen S.K. Ho are co-inventors of the PolyU-held patent for the hand exoskeleton robot, whose modified version is used in this study. For the submitted work, however, all authors have no financial relationship whatsoever with Rehab-Robotics Company Ltd., the company which manufactures the commercial version of the original device under license to the Hong Kong Polytechnic University (PolyU).

ORCID

Evan A. Susanto http://orcid.org/0000-0002-2037-6182

Raymond K.Y. Tong http://orcid.org/0000-0003-4375-653X

Additional information

Funding

This work was supported by a GRF grant from the Research Grants Council [PolyU 5318/09E] and the Innovation and Technology Fund of the Hong Kong Special Administrative Region [HKSAR ITT/004/12GP].

Notes on contributors

Mr Evan A. Susanto is currently a Ph.D. candidate in the Interdisciplinary Division of Biomedical Engineering at the Hong Kong Polytechnic University, where he also received his B.Sc. (Hons) degree in Biomedical Engineering. His current research areas include stroke rehabilitation, robotic systems, biomedical instrumentation and biomedical signal processing.

Ir Prof Raymond K.Y. Tong received his Ph.D. degree in Bioengineering from the University of Strathclyde, Glasgow, the UK in 1998. He is a Professor in the Division of Biomedical Engineering at the Chinese University of Hong Kong. His research interests include rehabilitation robotics, functional electrical stimulation, stroke rat modelling and BCI training rehabilitation on persons who have experienced a stroke.

Mr Newmen S.K. Ho received his BEng degree in Electrical Engineering from the University of Sydney, Australia in 1997. He obtained his M.Sc. degree in Computer Engineering from the University of New South Wales, Australia in 2001. He is currently studying for his Ph.D. degree in the Interdisciplinary Division of Biomedical Engineering at the Hong Kong Polytechnic University, with research interests in rehabilitation robotics for persons who have experienced a stroke.