A 40-year-old man developed slowly progressive muscle atrophy in his c
alf muscle. The patient became aware of asymmetry of his right big toe
during in his teens; muscle atrophy was revealed at the age of 25 yea
rs. Multi-image examinations revealed ''tethered cord syndrome'' with
spina bifida occulta. Spinal magnetic resonance image revealed a patho
genetic mechanism of asymmetry of muscle atrophy in the calf muscle. T
his suggested that spinal MRI imaging is one of the most useful diagno
stic methods for this disease.