JUVENILE AMYOTROPHY OF THE DISTAL UPPER EXTREMITY - PATHOLOGICAL FINDINGS OF THE DURA-MATER AND SURGICAL-MANAGEMENT

Study Design. Five cases of juvenile amyotrophy of the distal upper ex tremity were reviewed retrospectively to elucidate the pathophysiology of spinal cord dysfunction and the results of surgical management. Ob jectives. To clarify the pathogenesis of juvenile amyotrophy of the di stal upper extremity and to present the results of a new surgical trea tment. Summary of Background Data. Hirayama first reported this disord er in 1959. It is characterized by juvenile onset, slow progression, a nd involvement of the unilateral distal upper extremity. Recently, com pression of the cervical spinal cord during neck flexion was implicate d as a possible etiology of the disorder, but the exact etiology is st ill unknown. The value of surgical treatment for patients with juvenil e amyotrophy of the distal upper extremity has not been established. M ethods. The clinical and radiographic characteristics of five patients with juvenile amyotrophy of the distal upper extremity were examined. All five patients were treated surgically with duraplasty in combinat ion with posterior spinal fusion. Dynamic and computed tomographic mye lography were performed before and after surgery. Intraoperative ultra sonography and conductive spinal cord evoked potentials were recorded before and after duraplasty. The surgical results and the histology of the resected dura were studied. Results. Myelograms taken with the ne ck in a neutral position showed that the spinal cord was flattened in all five patients. When the neck was flexed, the dura and the spinal c ord were compressed further. Intraoperative ultrasonography during nec k flexion revealed an anterior shift of the spinal ord and decreased s pinal cord pulsation. Amplitude of the conductive spinal cord evoked p otentials decreased with neck flexion but increased after dural incisi on. Histologically, the dura appeared abnormal in that it contained fe w elastic fibers without the normal wavy structure. Conclusions. Juven ile amyotrophy of the distal upper extremity was characterized by inel astic dura that constricts and compresses the cervical spinal cord whe n the neck is in either a neutral or a flexed position. Abnormal dura appeared to be the cause of juvenile amyotrophy of the distal upper ex tremity. Duraplasty with spinal fusion are proposed as treatments.