Patterns of muscle atrophy in the lower limbs in patients with Charcot-Marie-Tooth disease as measured by magnetic resonance imaging.

Intrinsic atrophy of the calf musculature is a common finding in Charcot-Marie-Tooth disease. Peroneal nerve atrophy leading to weakness in the anterior and lateral compartments is the most common clinical pattern, but considerable variability exists in the pattern of atrophy. Magnetic resonance imaging offers a valuable method for identifying the distribution and symmetry of muscle degeneration. Twenty-three patients with Charcot-Marie-Tooth disease had axial T-1 magnetic resonance images obtained at proximal, middle and distal calf muscle locations. Areas of fatty infiltration and muscle atrophy were measured in the four calf muscle compartments. The worst areas of involvement, on a scale of one to four, with four being worst, were in the lateral compartment in the mid calf (mean, 2.5) and in the anterior, posterior and lateral compartments of the distal calf (2.6, 2.8 and 2.5). Comparing right and left legs showed that there was visible asymmetry, which was not statistically significant. There was considerable variation in the pattern of involvement from patient to patient. The fact that all four calf muscle compartments may be involved asymmetrically and in varying degrees is important for treatment planning, including surgery. Not all patients have the classic symmetrical peroneal pattern of denervation.