[Anterior shift of posterior lower cervical dura mater in patients with juvenile muscular atrophy of unilateral upper extremity].

Myelography was performed in 16 male patients with juvenile muscular atrophy of unilateral upper extremity. The age at onset ranged from 11 to 19 years (average, 16 years), and the age at study ranged from 15 to 38 years (average, 25 years). The most remarkable finding was an anterior shift of lower cervical dural canal during neck flexion, particularly of its posterior wall at around 6th vertebral level. The above finding was clearly shown in 12 patients whose duration of illness was under 20 years but not in 4 patients whose duration of illness was 20 years or over. And the rates of anterior shift of posterior lower cervical dura mater was inversely proportional to the duration of illness. There was a tendency that the greater the degree of the anterior dural shift and compression of the spinal cord, the greater the severity of the disease. We thought that the anterior shift of the posterior lower cervical dura mater provides the clue to understanding of its etiology and methods of arresting the progression of the disease.