Management of the Most Severe Dystrophic Cervical Kyphosis (140 degrees) in Neurofibromatosis Type 1

Abstract

Summary: A severe case of dystrophic cervical kyphosis due to neurofibromatosis is presented. The deformity and neurological deficit was improved by halo traction prior to posterior spinal fusion. Due to extensive vertebral bone loss and presence of plexiform neurofibromata at the head and neck region, a new pillar of bone was created posteriorly using a combination of bone morphogenetic protein 2 (BMP-2), autogenic, and allogenic bone graft to support the skull. Hypothesis: Stable fixation is important for solid fusion. BMP-2 can be used to promote fusion and formation of bony column. Design: Case Report Introduction: Dural ectasia can cause progressive bony erosion, vertebral collapse and neurological deficit. Spinal reconstruction is often difficult due to extensive bone loss. Methods: A 6-years-old boy with Type-1 Neurofibromatosis had an intradural neurofibroma at C1. Tumour excision was performed after C1 posterior arch excision and enlargement of the foramen magnum. He remained functionally and neurologically intact despite progressive cervical kyphosis. At 15 years old, he developed neck pain, right upper limb weakness, and myelopathic hand signs. Subsequent investigations revealed C1/2 instability, cervical kyphosis and C4/5 dislocation. C2-5 laminectomy and C0-T2 posterior fusion were attempted using autogenous rib grafts with postoperative halo-vest immobilization. His neurological status remained unchanged in subsequent 3 years but cervical kyphosis progressively deteriorated. At 18 years old, he developed tetraplegia and a 140-degrees cervical kyphosis (Fig 1a). PET showed no malignant neurofibroma. The kyphosis was reduced to 80 degrees by halo traction with an increasing force from 3 Kg to 24 Kg over a period of 2 months. His neurology normalized after traction. Occiput-to-T7 posterior instrumented fusion using mixture of iliac crest autograft, femoral head allograft and 12mg BMP-2. BMP-2 was used because of prior failure of fusion and extensive bony deficiency. Informed consent of using BMP-2 was obtained. Results: No wound, airway and neurological complication was noted after surgery. The postoperative kyphotic angle was 100 degrees and was maintained at 1 year follow-up (Fig 1b). CT scan demonstrated well-formed posterior bony column (Fig 1c) and PET scan 1-year postoperatively did not reveal malignant transformation of the plexiform neurofibromata. Conclusion Stable fixation and adequate bone grafting is necessary to reconstruct a dystrophic cervical kyphosis. BMP-II is not contraindicated but clinicians should balance the potential risks.