Comparison of Modified Ashworth Scale with Systems and Techniques for Quantitative Assessment of Spasticity-Literature Review

Spasticity is a disorder commonly found in people having upper motor neuron lesion and whose involvement can happen at different levels. The Modified Ashworth Scale (MAS) is the most routinely used instrument in clinical practice to assign spasticity levels. However, due to its inherent subjectivity, inter-evaluator discrepancies arise. Therefore, there are systems that quantitatively evaluate spasticity. This study is a literature review which aims to describe technologies for quantitative assessment of spasticity and discuss their effectiveness compared to MAS. The 27 selected papers were retrieved from PubMed, CAPES Portal, SciELO, MEDLINE and IEEE Xplore databases. Most of them had clinical goals involving patients with disorders of unique etiology. Thus, 48% and 30% of the surveyed papers included only patients with spasticity caused by stroke and cerebral palsy, respectively. Only 11% of the papers involved more than one etiology in the same trial. The remaining papers (11%) did not detail spasticity etiology. The results revealed different evaluative approaches including biomechanical data based on torque, joint angle, angular speed and muscle vibration, as well as neurophysiological approaches that analyzed electromyography signals of agonist and/or antagonist muscles. The integration of both approaches was also observed. Although MAS is widely used, quantitative assessment methods are more sensitive than MAS and, therefore, they are more suitable and safe for classifying spasticity. In conclusion, MAS should be replaced by quantitative tools, but it was not possible to determine the most effective measure for its replacement.