[Correlation between clinical features and neuroradiological findings in juvenile muscular atrophy of unilateral upper extremity (Hirayama disease)--with and without "tight dural canal in flexion"].

Myelography was performed in 12 patients with juvenile muscular atrophy of unilateral upper extremity. Seven patients showed anterior shift of lower cervical dural canal in flexion (tight dural canal in flexion) (T group), however the other 5 patients did not show "tight dural canal in flexion" (NT group). Onset of illness and sex were not different between 2 groups. However, there was a tendency that the neurological signs and symptoms were more severe in the patients of T group than those of NT group. These results suggest that "right dural canal in flexion" can be one of mechanisms which exhibit the clinical symptoms of the juvenile muscular atrophy of unilateral upper extremity. However, there may be other etiological factors in the juvenile muscular atrophy of unilateral upper extremity.