Modified Ashworth Scale and Alpha Motor Neuron Excitability Indicators of F-wave in Spastic Soleus Muscle Early after Stroke

Aims: Plantar flexor spasticity affects walking ability after stroke. Spasticity is clinically tested by modified Ashworth Scale (MAS) and it is fairly reliable. The aim of this study was to test the correlation between MAS and alpha motor neuron excitability indicators of F-wave in spastic soleus muscles early after stroke.

Place and Duration of Study: Neurophysiology laboratory, Kasturba Medical College, Mangalore, India and between June 2010- August 2012.

Methodology: Twenty three people with post stroke duration of 2.26 (1.18) months and MAS score > 1 on soleus muscle participated in this cross-sectional study. Modified Ashworth Scale and F-wave procedures were administered on spastic soleus muscle and the relationship was tested by Spearman’s rank correlation coefficient.

Results: The correlation of MAS to persistence of F-wave was high (r=0.842; p=<0.0001), but not with latency of F-wave (r= -0.264; p=0.223). A moderate correlation was found for post stoke duration to F-wave persistence (r=0.45; p=0.013) and the relation was nonlinear with latency of F-wave (r=0.016; p=0.950).

Conclusion: Modified Ashworth scale may be a tool to measure the neural aspects of soleus muscle spasticity i.e. alpha motor neuron excitability in people with early stage stroke.