Biomechanical investigation of the modified Tardieu Scale in assessing knee extensor spasticity poststroke

Technology-assisted assessment of spasticity: a systematic review

BACKGROUND

Spasticity is defined as "a motor disorder characterised by a velocity dependent increase in tonic stretch reflexes (muscle tone) with exaggerated tendon jerks". It is a highly prevalent condition following stroke and other neurological conditions. Clinical assessment of spasticity relies predominantly on manual, non-instrumented, clinical scales. Technology based solutions have been developed in the last decades to offer more specific, sensitive and accurate alternatives but no consensus exists on these different approaches.

METHOD

A systematic review of literature of technology-based methods aiming at the assessment of spasticity was performed. The approaches taken in the studies were classified based on the method used as well as their outcome measures. The psychometric properties and usability of the methods and outcome measures reported were evaluated.

RESULTS

124 studies were included in the analysis. 78 different outcome measures were identified, among which seven were used in more than 10 different studies each. The different methods rely on a wide range of different equipment (from robotic systems to simple goniometers) affecting their cost and usability. Studies equivalently applied to the lower and upper limbs (48% and 52%, respectively). A majority of studies applied to a stroke population (N = 79). More than half the papers did not report thoroughly the psychometric properties of the measures. Analysis identified that only 54 studies used measures specific to spasticity. Repeatability and discriminant validity were found to be of good quality in respectively 25 and 42 studies but were most often not evaluated (N = 95 and N = 78). Clinical validity was commonly assessed only against clinical scales (N = 33). Sensitivity of the measure was assessed in only three studies.

CONCLUSION

The development of a large diversity of assessment approaches appears to be done at the expense of their careful evaluation. Still, among the well validated approaches, the ones based on manual stretching and measuring a muscle activity reaction and the ones leveraging controlled stretches while isolating the stretch-reflex torque component appear as the two promising practical alternatives to clinical scales. These methods should be further evaluated, including on their sensitivity, to fully inform on their potential.

Measuring muscle tone with isokinetic dynamometer technique in stroke patients

Study aim: Increased muscle tone, a common consequence of stroke, has neural and non-neural components. Spasticity is related to the neural component. Non-neural resistance arises from passive stiffness. This study was designed to assess the feasibility of using isokinetic dynamometry to evaluate wrist flexor muscle spasticity in stroke patients.

Materials and methods: Twenty-six patients with hemiplegia in the subacute phase of stroke participated in this study. An isokinetic dynamometer was used to stretch wrist flexor muscles at four velocities of 5, 60, 120 and 180°/s on both the paretic and non-paretic sides. Peak torque at the lowest speed (5°/s) and reflex torque at the three higher speeds were quantified. Peak torque at the lowest speed was attributed to the non-neural component of muscle tone, and was subtracted from the torque response at higher velocities to estimate reflex torque (spasticity). Data from the two sides were compared.

Results: There was no significant difference in peak torque between the paretic (2.47 ± 0.22 N·m) and non-paretic side (2.41 ± 0.28 N·m) at the lowest velocity of 5°/s (p=0.408). However, compared to the non-paretic side, the paretic side showed higher reflex torque (p<0001), and reflex torque increased rapidly with increasing velocity (p < 0.05).

Conclusion: The isokinetic dynamometer distinguished spasticity from the non-neural component and showed higher reflex torque on the paretic side compared to the non-paretic side. This instrument is potentially useful to assess the efficacy of therapeutic interventions aimed at modifying spasticity.