The unreliability of clinical measures of muscle tone: implications for stroke therapy

Abstract

Background: the central tenet of the neurofacilitatory approach to stroke therapy is that muscle tone needs to be normal before normal movement can occur. A reliable clinical measure of the full spectrum of muscle tone is needed to test: (i) the purported relationship between muscle tone, other motor impairments and disability, and (ii) the effectiveness of stroke therapy to restore movement. Aim: the purpose of the study was to test the inter-rater reliability of clinical categorization of muscle tone (spastic/normal/flaccid) and also a visual analogue scale with anchor points of 'lowest tone possible' (score 0) and 'highest tone possible' (score 100). Methods: four independent raters assessed tone of elbow flexors and knee extensors of 14 stroke rehabilitation inpatients using the categorical scale. Six independent raters assessed tone of elbow flexors and knee extensors of 25 chronic stroke patients and two healthy volunteers using the visual analogue scale. All assessment orders were randomized. Results: both scales were unreliable, with k coefficients for the categorical scale ranging from -0.046 to 0.56 for the categorical scale, and intra-class correlation coefficients for the visual analogue scale of 0.595 for elbow flexors and 0.451 for knee extensors. Assessment order effects for the visual analogue scale were non-significant for elbow flexors (P ¼ 0.545) and knee extensors (P ¼ 0.911). Conclusions: these results, and those of earlier studies, suggest that clinical measures of muscle tone are consistently unreliable. Systematic investigation of the therapy rationale for planning and evaluating treatment is required before relevant clinical measures can be developed.

Assessment of spasticity after stroke using clinical measures: a systematic review

“…Also, using a goniometer the full range of motion of the joint and the angle of catch resulting from passive stretch are measured to determine the level of dynamic contracture in the joint [16][17][18]. One study in our review described categorizing tone and using a VAS as two approaches to assess spasticity [42]. For tone categorization, the limb is classified as spastic, flaccid or normal.…”

“…For tone categorization, the limb is classified as spastic, flaccid or normal. For the VAS, muscle tone is evaluated using a 100-mm vertical VAS with anchor points at the top and bottom for highest and lowest muscle tone, respectively [42]. (iii) Ankle plantarflexors tone scale (APTS): The APTS is divided into three sub-tests [43].…”

“…Table 3 summarizes the reliability of spasticity measures included in this review. In total, the reliability of ASs was reported in six studies [68][69][70][71][72][73], TSs in three [74][75][76], multi-item scales in five [41][42][43][44]71], electrophysiological measures in two [27,46], and force/torque measures in two [51,77]. There were no reports on the reliability of the elbow pendulum test or the manual sinusoidal method.…”

Myotonometric Measurement of Muscular Properties of Hemiparetic Arms in Stroke Patients

“…The reliability and validity of both scales have also been questioned (Aarrestad et al, 2004;Katz & Rymer, 1989;Leonard et al, 2003;Pandyan et al, 1999;Pomeroy et al, 2000).…”

Development of novel devices for upper-extremity rehabilitation

“…The expression of hyperactive reflexes is felt as increased muscle tone or joint resistance when it depends on the muscle-length feedback (through Iastatic and II afferents) [160,158,135,136]. When dependent on the musclespeed feedback (through Ia-dynamic afferents), the effects are described as spasticity [113,114,3].…”