Abstract
Background Commonly used spasticity scales assess the resistance felt by the evaluator during passive stretching. These scales, however, have questionable validity and reliability. The tonic stretch reflex threshold (TSRT), or the angle at which motoneuronal recruitment begins in the resting state, is a promising alternative for spasticity measurement. Previous studies showed that spasticity and voluntary motor deficits after stroke may be characterized by a limitation in the ability of the central nervous system to regulate the range of the TSRT.
Objective The study objective was to assess interevaluator reliability for TSRT plantar-flexor spasticity measurement.
Design This was an interevaluator reliability study.
Methods In 28 people after stroke, plantar-flexor spasticity was evaluated twice on the same day. Plantar-flexor muscles were stretched 20 times at different velocities assigned by a portable device. Plantar-flexor electromyographic signals and ankle angles were used to determine dynamic velocity-dependent thresholds. The TSRT was computed by extrapolating a regression line through dynamic velocity-dependent thresholds to the angular axis.
Results Mean TSRTs in evaluations 1 and 2 were 66.0 degrees (SD=13.1°) and 65.8 degrees (SD=14.1°), respectively, with no significant difference between them. The intraclass correlation coefficient (2,1) was .851 (95% confidence interval=.703, .928).
Limitations The notion of dynamic stretch reflex threshold does not exclude the possibility that spasticity is dependent on acceleration, as well as on velocity; future work will study both possibilities.
Conclusions Tonic stretch reflex threshold interevaluator reliability for evaluating stroke-related plantar-flexor spasticity was very good. The TSRT is a reliable measure of spasticity. More information may be gained by combining the TSRT measurement with a measure of velocity-dependent resistance.
Footnotes
Ms Mullick and Dr Levin provided concept/idea/research design. Dr Blanchette and Dr Levin provided writing and project management. All authors provided data collection and reviewed the manuscript before submission. Dr Blanchette, Ms Moïn-Darbari, and Dr Levin provided data analysis. Dr Levin provided fund procurement, participants, facilities/equipment, institutional liaisons, administrative support, and consultation (including review of manuscript before submission). The authors thank Rhona Guberek, Sandeep Subramanian, Revital Hacmon, Vanessa Gatti, and Ruth Dannenbaum for their help in data collection. They also thank Christian Beaudoin and Valeri Goussev for their valuable contributions in software programming and Eric Johnstone for technical support.
This study was approved by the CRIR Ethics Review Board.
This work was supported by the Canadian Physiotherapy Foundation, Univalor, and Collaborative Health Research Projects.
Dr Levin owns part of the intellectual property rights for the spasticity measurement device used in the study.
- Received May 28, 2014.
- Accepted October 4, 2015.
- © 2016 American Physical Therapy Association
Issue highlights
