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Neurofibromatosis-1 is a disorder of neural crest cells that is due to a defect in the gene neurofibromin, a tumor suppressor gene found on chromosome 17. The disease is transmitted in an autosomal dominant fashion with high penetrance, although 50% of patients acquire it as a new mutation. Diagnosis require at least two of the National Institutes of Health criteria: six cafe au lait spots, at least two neurofibromas, axillary or inguinal freckling, optic glioma, iris hamartomas, distinct osseous lesion, or an affected first-degree relative. Scoliosis in NF-1 may be idiopathic-like or dystrophic. The idiopathic-like curves may be managed by traditional methods. The dystrophic type is less common, but much harder to manage. It is characterized by a short, sharp, single thoracic curve with four to six involved vertebrae having three or more dystrophic features. Dystrophic features include severe rotation, anterior or posterior vertebral scalloping, vertebral wedging, widened neural foramina, spindling of the transverse processes, penciling of the ribs, and an angular kyphosis. Spinal dislocation and paraplegia may even develop despite the usually large canal observed in dystrophic types. Some curves that initially do not have dystrophic features may "modulate" into a dystrophic type with time.
This is especially true in spinal deformities that develop before age 7. The kyphosis in dystrophic curves usually develops over time. All patients with neurofibromatosis should undergo magnetic resonance imaging (MRI) of the entire spine prior to surgery to detect any intraspinal mass lesions. |
