Functional muscle balance assessment in multiple sclerosis

Chronic demyelinisation in multiple sclerosis (MS) involves changes in the muscle structure and development of motor disorders.

The aim of this research is to assess the muscle balance of thigh muscle in MS using a noninvasive method, to have information about the muscle status prior to the rehabilitation and to prevent muscle damage.

The studied group consisted of 20 patients: 9 men and 11 women, with a mean age of 42 years. The patients were diagnosed with MS in different stages. The clinical evaluation included clinical examination, neurological examination, functional evaluation by using the Hamilton score, the activity daily living (ADL) scale and the Kurtze (EDSS) scale. For the muscle assessment we used tensiomyography (TMG), an evaluation method for the functional potential of the muscle, depending on the muscle composition. The TMG parameters are displacement (Dm), contraction time (Tc) and sustain time (Ts) for biceps femoris (mBF) and rectus femoris (mRF).

The value of Dm shows low values for both studied muscle groups, but closer to the normal value for mBF. The average normal Tc values for mBF are 30.25 ± 3.5 ms and 32.83 ± 4.5 for mRF. The values are low values for mRF and high for mBF. The normal values of Ts are not standard values and can be compared healthy individuals' values. These parameters could monitor the evolution and in our research have lower values for mRF. In the thigh, there was a significant difference in the Dm values, with higher values in mBF and also with higher values in the right lower limb. Analyzing the Ts results, we noticed a difference between the two muscle groups with a significant reduction in mRF, showing the inability to achieve anterior-posterior symmetry and the tendency to develop type I fibers at mBF level.

Our study showed the presence of a structural and functional asymmetry explained by the tendency of increasing the tonus at mRF level in order to compensate the knee stability. We noticed a decrease in Tc value at the mRF level, but close to the value of the two lower limbs. TMG analysis revealed the asymmetry of the muscle composition at the level of the antagonist muscle groups of the thigh, with an increase in the percentage of type II fibers in the previous group, which became hyperton, and a decrease in the percentage of type I fibers in the posterior group.