Multiple sclerosis (MS) is characterised by complex and heterogeneous symptoms, often leading to reduced quality of life and impaired functional capacity. The latter is related to reduced muscle strength of predominately the lower limbs . The mechanisms underlying the observed strength deficits are of muscular as well as neural origin . At the whole muscle level, a number of studies have examined skeletal muscle characteristics of MS patients, with some studies but not all, reporting loss of muscle mass and decreased or comparable maximal muscle strength.
However, there is no study describing the features of lower extremity muscle architecture in multiple sclerosis. Muscle architecture is defined as the alignment of muscle fibers with respect to the axis of force. Although the diameters of the muscles of different sizes are quite similar to the diameters of the fibers, the sequences of these fibers contain several differences. The alignment of the muscle forming fibers has a significant effect on the force of muscle formation. The parameters that determine muscle architecture characteristics are the muscle fiber length, pennation angle, the physiological cross-sectional area. For each muscle these parameters may differ from each other. Any type of load in the case is the result of an adaptation process that results in muscle development. Muscle architecture allows the macroscopic understanding and interpretation of this adaptation process.
Determining the muscle architecture of multiple sclerosis patients by ultrasound will guide the rehabilitation process.
