Congenital anteroposterior spinal dissociation in Larsen's Syndrome: report on two operated cases with long-term follow-up.

Abstract

STUDY DESIGN: The outcome of two patients with Larsen's syndrome after spinal surgery was evaluated after follow-up for 9 and 16 years. OBJECTIVE: To report on a new phenomenon of anteroposterior dissociation of the vertebrae in Larsen's syndrome. To demonstrate that it can be visualized before surgery with imaging and also seen intraoperatively. To show that the neurologic recovery after surgery is sustained and to review the technical reasons for the difficulties in achieving a surgical fusion. The critical role of CT scanning will be illustrated. SUMMARY OF BACKGROUND DATA: The results of preoperative and postoperative radiologic investigations and intraoperative findings are presented to support this new phenomenon. METHODS: Two patients underwent multiple spinal surgeries because of a deteriorating myelopathic clinical status. Intraoperatively, anteroposterior dissociation was documented in both patients. There was great difficulty in obtaining a surgical fusion, and an unusually long circumferential fusion was eventually necessary to obtain stability. Prolonged halo-vest immobilization was essential. RESULTS: Neurologic recovery was sustained over time, and the spinal deformity did not deteriorate. CONCLUSION: Awareness of this phenomenon is essential to the management of spinal deformities in Larsen's syndrome when presenting with myelopathy. Special features in the radiologic workup should be sought after so as to plan staged surgical procedures. Conventional principles of planning of fusion levels are inadequate. Early treatment is advocated, as the neurologic compromise is reversible.