[Computed tomographic analyses on skeletal muscles in bulbar spinal muscular atrophy]

We analysed the patterns of skeletal muscular involvement in 18 patients with bulbar-spinal muscular atrophy (BSMA) of the Kennedy-Alter-Sung type by using the computed tomographic scanner. Fatty infiltrations were prominent in various skeletal muscles of extremities and trunk, and its degree was severe in the following numerical orders; the gluteal muscles, flexors of the thighs, flexors of the lower extremities, extensors and the adductors of the thighs, the paraspinal muscles, and extensors of the lower extremities. There was statistically significant correlation between fatty infiltrations in flexors of the lower extremities and duration of illness. And were noted findings that the skeletal muscle lesion progressed with the preserved fasciae and sectional areas, fatty infiltrations in the lower extremities were more conspicuous in flexors than in extensors, and compensatory hypertrophic muscles in the thigh were apparent in 50% of cases. In conclusions, the computed tomographic analyses on skeletal muscle of BSMA may be useful to detect distributions, progression of the muscle lesion, in addition to a profile of the myopathic alterations of the disease.