A preliminary study into the criterion validity of the Modified Modified Ashworth Scale using the new measure of the alpha motoneuron excitability in spastic hemiplegia

Abstract

The Modified Ashworth Scale (MAS) is the most widely used clinical test for the measurement of muscle spasticity. This scale that suffers from limitations and lack of reliability and validity has recently been remodified. The aim of the present study is to investigate the criterion validity of the new Modified MAS(MMAS) in the upper limb in post-stroke hemiplegia, using the Hslope/Mslope (Hslp/Mslp) as a novel index of alpha motor neuron excitability. Prior to the validity study, the reliability of the MMAS was evaluated in 30 hemiplegic patients. The raters agreed on 23 patients (0. 76%). The MMAS had good inter-rater reliability (K= 0.63, SE = 0.11, p < 0.001) for the assessment of wrist flexors spasticity in hemiplegic patients. 12 adult patients (7 women and 5 men) with first ever stroke resulting in hemiplegia with a mean age of 58.9 +/- 11.9 years (range, 37-73) were included in the validity study. The outcome measures were the MMAS for the clinical assessment of spasticity, and the HslopelMslope and the Hmax/Mmax ratio for the electrophysiological evaluation. The results showed an increase in mean rank of Hslp / Mslp in patients with a score of 1, 2 or 3 on the MMAS. However, the difference among the groups was not significant (p > 0.05). There was also no relationship between the clinical scale of MMAS and either the traditional [Hmax / Mmax ratio (r = -0.06)] or the new index [Hslp / Mslp (r = 0.24)] of spinal excitability. This preliminary study recruited a small number of patients, and failed to confirm a linear correlation between these variables. A study with a large number of patients is suggested to clarify the outcome.