**4.5 Data analysis**

Statistical analyses were performed with SPSS version 16.0 software (SPSS Inc, Chicago, IL USA) and values of *P*< 0.05 were considered statistically significant. The analysis of variance (ANOVA) was used to compare the baseline and posttreatment characteristics of the 3 affected muscles. The Bonferroni method was used for post hoc pairwise comparisons.

Test-retest reliability of the Myoton-3 was determined by using the intraclass correlation coefficient (ICC) with 95% confidence intervals (CIs); an ICC value exceeding 0.80 indicated high reliability (Weir, 2005).

Concurrent validity of the Myoton-3 was determined using the Pearson correlation (*r*) test to establish relationships with hand strength and the Spearman rho (ρ) test to calculate the degree of correlations with the ARAT and Brunnstrom stage, respectively. The strength of correlations was interpreted as low (0.00-0.25), fair (0.25-0.50), moderate to good (0.50-0.75), and good to excellent (>0.75) (Portney, 2009).

The standardized response mean (SRM) was used as the index of the responsiveness of the Myoton-3 according to changes of the affected and unaffected limbs from pretreatment to postest. The SRM was estimated as the ratio of the mean change scores to the standard deviation of the change scores from patients whose myotonometric measures improved over time (i.e., the change score from pretreatment to posttreatment was negative in muscle properties), and the values were categorized as large (>0.8), moderate (0.5-0.8), and small (0.2-0.5) (Cohen, 1988).

## **4.6 Results**

#### **4.6.1 Comparison of the muscular properties of the extensor digitorum, flexor carpi radialis, and flexor carpi ulnaris at pretreatment and posttreatment**

Table 1 summarizes the mean (SD) of the myotonometric measurements for muscle tone, elasticity, and stiffness of the extensor digitorum, flexor carpi radialis, and flexor carpi ulnaris muscles at pretreatment and posttreatment.


Table 1. Mean and standard deviation of the myotonometric measurements for muscular properties of the 3 affected forearm muscles

The Myoton-3 measures, as well as criterion measures for hand strength, including grip strength, lateral pinch power, and palmar pinch power, the Action Research Arm Test

Statistical analyses were performed with SPSS version 16.0 software (SPSS Inc, Chicago, IL USA) and values of *P*< 0.05 were considered statistically significant. The analysis of variance (ANOVA) was used to compare the baseline and posttreatment characteristics of the 3 affected muscles. The Bonferroni method was used for post hoc pairwise comparisons.

Test-retest reliability of the Myoton-3 was determined by using the intraclass correlation coefficient (ICC) with 95% confidence intervals (CIs); an ICC value exceeding 0.80 indicated

Concurrent validity of the Myoton-3 was determined using the Pearson correlation (*r*) test to establish relationships with hand strength and the Spearman rho (ρ) test to calculate the degree of correlations with the ARAT and Brunnstrom stage, respectively. The strength of correlations was interpreted as low (0.00-0.25), fair (0.25-0.50), moderate to good (0.50-0.75),

The standardized response mean (SRM) was used as the index of the responsiveness of the Myoton-3 according to changes of the affected and unaffected limbs from pretreatment to postest. The SRM was estimated as the ratio of the mean change scores to the standard deviation of the change scores from patients whose myotonometric measures improved over time (i.e., the change score from pretreatment to posttreatment was negative in muscle properties), and the values were categorized as large (>0.8), moderate (0.5-0.8), and small

**4.6.1 Comparison of the muscular properties of the extensor digitorum, flexor carpi** 

Table 1 summarizes the mean (SD) of the myotonometric measurements for muscle tone, elasticity, and stiffness of the extensor digitorum, flexor carpi radialis, and flexor carpi

> Extensor digitorum

Table 1. Mean and standard deviation of the myotonometric measurements for muscular

Tone (Hz) 17.60 (2.82) 14.78 (3.01) 13.45 (2.80) Elasticity 1.89 (0.27) 1.31 (0.31) 1.35 (0.33) Stiffness (N/m) 354.90 (62.16) 297.85 (65.47) 272.85 (57.72)

Tone (Hz) 17.03 (2.64) 15.03 (3.19) 13.39 (2.40) Elasticity 1.84 (0.34) 1.31 (0.40) 1.40 (0.34) Stiffness (N/m) 341.24 (51.02) 309.26 (74.09) 268.94 (55.05)

Flexor carpi radialis

Flexor carpi ulnaris

**radialis, and flexor carpi ulnaris at pretreatment and posttreatment** 

(ARAT), and Brunnstrom stage were performed before and after treatments.

**4.4 Criterion measures** 

**4.5 Data analysis** 

high reliability (Weir, 2005).

(0.2-0.5) (Cohen, 1988).

**4.6 Results** 

Pretreatment Mean (SD)

Posttreatment Mean (SD)

and good to excellent (>0.75) (Portney, 2009).

ulnaris muscles at pretreatment and posttreatment.

properties

properties of the 3 affected forearm muscles

Muscular

Results of the ANOVA showed a significant difference in muscle tone, elasticity, and stiffness among the 3 affected muscles before and after treatment (*P* < 0.0001). Post hoc analyses revealed that muscle tone and stiffness of the extensor digitorum were significantly higher than those of the flexor carpi radialis and flexor carpi ulnaris at both pretreatment and posttreatment (pretreatment tone and stiffness: *P* < 0.0001, posttreatment tone: *P* < 0.0001, posttreatment stiffness: *P* = 0.008, *P* < 0.0001, resepctively). Muscle tone of the flexor carpi radialis was significantly higher than that of flexor carpi ulnaris at pretreatment and posttreatment (*P* = 0.025, 0.002, respectively). Muscle stiffness of the flexor carpi radialis was significantly higher than that of flexor carpi ulnaris at posttreatment (*P* = 0.001). Muscle elasticity of the extensor digitorum was significantly lower than the elasticity of flexor carpi radialis and flexor carpi ulnaris at both pretreatment and posttreatment (*P*< 0.0001, *P*< 0.0001, respectively). In general, the extensor digitorum showed higher tone and stiffness with lower elasticity compared to the flexor carpi radialis and ulnaris muscles.

#### **4.6.2 Reliability of the Myoton-3 myometer in patients with stroke**

The test-retest reliability was performed on a subset of 58 participants who underwent two pretreatment measurements. The Myoton-3 myometer showed high to very high test-retest reliability for muscle properties in affected extensor digitorum, flexor carpi radialis, and flexor carpi ulnaris (ICC, 0.86-0.96).

Our study indicated that the Myoton-3 is a highly reliable measurement tool with high testretest reliability under relaxed conditions in measurements of affected forearm muscles of stroke patients. These findings are similar to those reported of the myotonometer for different muscles and study populations. The reliability of the myotonometer was high in the biceps brachii, rectus femoris, biceps femoris, and gastrocnemius in healthy individuals (Bizzini & Mannion, 2003; Ditroilo et al., 2011; Leonard et al., 2003; Marusiak et al., 2010); the biceps brachii in patients with Parkinson's disease (Marusiak et al., 2010); and in the brachii, gastrocnemius, and rectus femoris in children with cerebral palsy (Aarrestad et al., 2004; Lidstrom et al., 2009). In general, the Myoton-3 myometer is reliable for measurements in healthy individuals as well as for various patient populations.

#### **4.6.3 Validity of the Myoton-3 myometer in patients with stroke**

Significant correlations existed between the tone and stiffness of the 3 muscles and palmar pinch strength, between those of the flexor carpi radialis & ulnaris muscles and lateral pinch strength, and between those of the flexor carpi radialis and the ARAT at posttreatment. The posttreatment elasticity of the two flexor carpi muscles was significantly correlated with grip strength. The pretreatment elasticity of the flexor carpi ulnaris was significantly correlated with posttreatment grip strength, and the pretreatment muscle tone and stiffness of the flexor carpi radialis were significantly correlated with palmar pinch strength and ARAT. There was no significant correlations existed between the Brunnstrom stage and muscle properties of the 3 muscles at pretreatment. Posttreatment extensor digitorum tone and flexor carpi radialis stiffness were significantly correlated with the Brunnstrom stage.

The results of the concurrent validity showed partly significant associations between forearm muscle properties and hand strength and UE motor function, especially at

Myotonometric Measurement of Muscular Properties of Hemiparetic Arms in Stroke Patients 47

 Resting muscle tone during the relaxed condition does not fully quantify spasticity, which is characterized by a velocity-dependent and should be adequately performed under a dynamic state. Further studies may compare biomechanical properties of the

 With a sufficient sample size, a comparison of change in the myotonometric measures between patients who improved and those who did not should be analyzed separately. Further substantiation and generalization of these findings in larger and more diverse

The Myoton-3 myometer measures mechanical properties of the skeletal muscle, which may provide new insights into muscle functions to diagnose and treat muscle pathophysiology. In clinical practice and research settings, performance documented by the Myoton-3 myometer might be a useful indicator of muscle changes. This overview showed that the Myoton-3 myometer could be applied as a reliable, valid, and responsive device for objectively quantifying muscle tone, elasticity, and stiffness of resting forearm muscles in patients with stroke. These findings support the use of myotonometric measurement in

This project was supported in part by the National Science Council (NSC 97-2314-B-002-008- MY3 and NSC 99-2314-B-182-014-MY3), and the National Health Research Institutes (NHRI-

Aarrestad, D. D., Williams, M. D., Fehrer, S. C., Mikhailenok, E., & Leonard, C. T. (2004).

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Bizzini, M., & Mannion, A. F. (2003). Reliability of a new, hand-held device for assessing

Bohannon, R. W., & Smith, M. B. (1987). Interrater reliability of a modified Ashworth scale of

Brunnstrom, S. (1970). *Movement Therapy in Hemiplegia*. Harper & Row, ISBN 0-397-54808-7,

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Intra- and interrater reliabilities of the Myotonometer when assessing the spastic condition of children with cerebral palsy. *Journal of Child Neurology,* Vol*.*19, No.11,

Mechanical properties of the plantarflexor musculotendinous unit during passive dorsiflexion in children with cerebral palsy compared with typically developing children. *Developmental Medicine and Child Neurology,* Vol*.*52, No.6, (Jun 2010),

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samples are warranted to determine clinical value of the Myoton-3.

resting muscles with the contracted muscle.

stroke rehabilitation and further clinical trials.

EX100-10010PI and NHRI-EX100-9920PI) in Taiwan.

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**6. Acknowledgements** 

ISSN 0268-0033

9023

New York

**7. References** 

**5. Conclusion** 

posttreatment, which indicates that they might measure similar constructs. Our present findings were compatible with those from a previous study reporting a correlation between muscle stiffness and muscle strength of the quadriceps (Bizzini & Mannion, 2003). In this study, the elasticity of the two wrist flexors tended to increase with greater grip strength at posttreatment. At posttreatment, the elasticity of the extensor digitorum and muscle tone and stiffness of the two wrist flexors tended to increase with greater lateral pinch strength. The muscle tone and stiffness of the extensor digitorum and the two wrist flexors appeared to increase with greater palmar pinch strength. The pretreatment and posttreatment muscle tone and stiffness of the flexor carpi radialis were correlated to palmar pinch strength and ARAT.

#### **4.6.4 Responsiveness of the Myoton-3 myometer in patients with stroke receiving rehabilitation**

The responsiveness of the extensor digitorum was higher than those of the flexor carpi radialis and ulnaris, with moderate to high for the affected extensor digitorum and small to moderate for the affected flexor carpi radialis and ulnaris. The responsiveness of the muscle tone and elasticity was moderate for the affected extensor digitorum and small for the affected flexor carpi radialis and ulnaris (tone: –0.57 vs –0.39 vs –0.35; elasticity: –0.75 vs – 0.44 vs –0.31). The responsiveness of the elasticity of the affected extensor digitorum was significantly higher than that of the affected flexor carpi ulnaris (difference in SRM, 0.44; 95% CI, –0.78 to –0.11). The responsiveness of muscle stiffness was high for the affected extensor digitorum (–0.83) and moderate for the affected flexor carpi radialis (–0.71) and ulnaris (–0.77).

The responsiveness of the Myoton-3 is an important outcome measure and may serve as the foundation for therapy guidance and evaluation. The responsiveness to change of myotonometric measurements can be calculated through numeric data, provide a basis for estimates of whether the changes of muscle parameters over time are in the desired direction, and thus permit rehabilitation therapies to be adjusted accordingly. Our SRM calculations showed the affected extensor digitorum appears to be more responsive than the affected flexor carpi radialis and ulnaris in muscle tone, elasticity, and stiffness, and especially elasticity (–0.75 vs –0.44 vs –0.31). This result may arise from an emphasis on activation of wrist and finger extensor muscles elicited by the rehabilitation program the patients received. Thus, the extensor digitorum was much facilitated after treatments, and the flexor carpi muscles were not as sensitive as the extensor digitorum. Given that the ability to sustain finger extension is necessary in most functional hand activities; active finger extension is an important prognostic determinant and an early valid indicator of favorable UE function after stroke (Fritz et al., 2005; Nijland et al., 2010). Stroke patients with early finger extension after onset had a 98% probability of regaining some dexterity and a 60% probability of achieving full functional recovery of the hemiplegic arm at 6 months after stroke (Nijland et al., 2010).

#### **4.6.5 Future directions**

 Different treatment effects across treatment groups could adversely affect variability. Future studies with a larger sample size may analyze changes after specific treatment.

