RESUMEN
INTRODUCTION: Spasticity is one of the most common and disabling symptoms in Multiple sclerosis (MS). The is a clinical tool for assessing spasticity. This study aimed to investigate the inter- and intra-rater reliability of the modified Tardieu scale for assessing knee extensors spasticity in MS patients. METHODS: Twenty-six patients with MS (12 females and 14 males) with a mean age of 40 ± 11.39 years participated in this study. The extensor muscles of both knees were evaluated using the MTS in two sessions. At first session, two examiners randomly assessed the knee extensor spasticity to study the inter-rater reliability and 3-4 days later the first examiner assessed the patients again, to determine intra-rater reliability. Intra-class Correlation Coefficient (ICC) analysis, two-way random effect model was used to determine the reliability of various components of the modified Tardieu scale. RESULTS: The inter-rater reliability for quality of muscle reaction of knee extensor muscles was very good (ICC = 0.89) and for the difference between the angle of muscle response (R1) and full range(R2) of movement (R2- R1), as spasticity intensity criterion, was good (ICC = 0.73). ICC values for R2-R1 and muscle response quality assessments by one rater were 0.73 and 0.82, respectively. CONCLUSION: The findings of the current study showed that the MTS has good to very good inter- and intra-rater reliability for assessing knee extensors spasticity in MS patients.