Background and Aim: Spasticity is a velocity-dependent increase in tonic stretch reflexes (muscle tone) with exaggerated tendon jerks, resulting from hyperexcitability of the stretch reflex. The measurement of spasticity is necessary to determine the effect of treatments. The Modified Ashworth Scale is the most widely used method for assessing muscle spasticity in clinical practice and research. The purpose of this study was to investigate the interrater reliability of Modified Ashworth Scale in hemiplegic patients.

Materials and Methods: Thirty subjects (16 males, 14 females) with a mean age of 59.40 (SD =14.013) recruited. Shoulder adductor , elbow flexor , wrist dorsiflexor , hip adductor , knee extensor and ankle plantarflexor on the hemiplegic side were tested by two physiotherapists.

Results: In the upper limb, the interrater reliability for shoulder adductor and elbow flexor muscles was fair (0.372 and 0.369, respectively). The reliability for the wrist flexors was good (0.612). The difference in Kappa value for the proximal muscle (shoulder adductor; 0.372) and the distal muscle (wrist flexor; 0.612) was significant (²X=33.87, df=1, p<0.05). In the lower limb, the reliability for the hip adductor was fair (0.350), but for the knee extensor and ankle plantar flexor was moderate (0.518 and 0.542, respectively). The Kappa value for the proximal muscle (hip adductor: 0.350) and distal muscle (ankle plantar flexor;0.542) had no significant difference (²X =1.35, df=1, p >0.05). The mean value for the upper limb (0.505) and the lower limb (0,.516) was not significantly different (²X=0.1407, df=1, p>0.05).

Conclusion: The interrater reliability of Modified Ashworth Scale was not good . The limb, upper or lower, had no significant effect on the reliability. In the upper limb, the reliability for the proximal and distal muscle was significantly different. However. The difference in the lower limb was not significant.When using the scale, one should consider it's limitation.