Magnetic resonance imaging in a juvenile type of distal and segmental muscular atrophy of the upper extremities

Eight patients with a juvenile type of distal and segmental muscular atrophy of the upper extremities (DSMA), a type of cervical flexion myelophathy, were evaluated using MR imaging. In the neutral position there was no spinal cord compression, but in flexion the spinal cord was displaced anteriorly and was compressed by the posterior surfaces or margins of the vertebrae and/or any herniated disks in all cases. In flexion, compression of the cord was exaggerated in seven patients by the anterior displacement of the posterior margin of the thecal sac, which was accompanied by dilated posterior internal vertebral veins. In patients suspected of having DSMA, MR images made in flexion are regarded essential for verifying the diagnosis.