Surgical treatment of scoliosis caused by neurofibromatosis type 1

Abstract

Objective: To retrospectively analyze the relationship between curve types and clinical results in surgical treatment of scoliosis in patients with neurofibromatosis type 1 (NF-1).

Methods: Forty-five patients with scoliosis resulting from NF-1 were treated surgically from 1984 to 2002. Mean age at operation was 14.2 years. There were 6 nondystrophic curves and 39 dystrophic curves depended on their radiographic features. According to their apical vertebrae location, the dystrophic curves were divided into three subgroups: thoracic curve (apical vertebra at T8 or above), thoracolumbar curve (apical vertebra below T8 and above L1), and lumber curve (apical vertebra at L1 and below). Posterior spine fusion, combined anterior and posterior spine fusion were administrated based on the type and location of the curves. Mean follow-up was 6.8 years. Clinical and radiological manifestations were investigated and results were assessed.

Results: Three patients with muscle weakness of low extremities recovered entirely. Two patients with dystrophic lumbar curve maintained their low back pain the same as preoperatively. The mean coronal and sagittal Cobb's angle in nondystrophic curves was 80.3 degrees and 61.7 degrees before operation, 30.7 degrees and 36.9 degrees after operation, and 32.9 degrees and 42.1 degrees at follow-up, respectively. In dystrophic thoracic curves, preoperative Cobb's angle in coronal and sagittal plane was 96.5 degrees and 79.8 degrees, postoperative 49.3 degrees and 41.7 degrees, follow-up 54.1 degrees and 45.3 degres, respectively. In thoracolumbar curves, preoperative Cobb's angle in coronal and sagittal plane was 75.0 degrees and 47.5 degrees, postoperative 31.2 degrees and 22.8 degrees, follow-up 37.5 degrees and 27.8 degrees, respectively. In lumbar curves preoperative Cobb's angle in coronal plane was 55.3 degrees, postoperative 19.3 degrees, and follow-up 32.1 degrees. Six patients with dystrophic curves had his or her curve deteriorated more than 10 degrees at follow-up. Three of them were in the thoracic subgroup and their kyphosis was larger than 95 degrees, and three in lumbar subgroup. Hardware failure occurred in 3 cases. Six patients had 7 revision procedures totally.

Conclusions: Posterior spinal fusion is effective for most dystrophic thoracic curves in patients whose kyphosis is less than 95 degrees. Combined anterior and posterior spinal fusion is stronger recommended for patients whose kyphosis is larger than 95 degrees and those whose apical vertebra is located below T8. Patients should be informed that repeated spine fusion might be necessary even after combined anterior and posterior spine fusion.