Cervical dural sac and spinal cord in juvenile muscular atrophy of distal upper extremity.

OBJECTIVE: To investigate specificity and significance of dynamic changes of the cervical dural sac and spinal cord during neck flexion in juvenile muscular atrophy of the distal upper extremity.

BACKGROUND: The disorder affects young people-predominantly men-and is progressive for several years. One autopsy case showed ischemic necrosis of the cervical anterior horn, suggesting that the disorder is a type of cervical myelopathy. Some authors classify it as monomelic amyotrophy, implying that it is a focal motor neuron disease.

METHODS: Neuroradiologic examinations including myelography, CT myelography, and MRI in a fully flexed neck position were performed on 73 patients with this disorder and on 20 disease control subjects.

RESULTS: A distinctive finding in the disorder was forward displacement of the cervical dural sac and compressive flattening of the lower cervical cord during neck flexion. The forward displacement was significantly greater in patients with disease duration less than 10 years than in age-matched control subjects and patients in a late, nonprogressive stage.

CONCLUSIONS: Radiologic abnormalities of the lower cervical dural sac and spinal cord support the hypothesis that this disorder is a type of cervical myelopathy.