Assessment of vertebral scalloping in neurofibromatosis type 1 with plain radiography and MRI

To evaluate vertebral scalloping in patients with neurofibromatosis type 1 (NF-1) and spinal deformity using plain radiographs and magnetic resonance imaging (MRI), and to determine the possible aetiological association with neurofibromas, dural ectasia and lateral meningocoeles.

Nineteen patients with NF-1, who had full spine radiographs and whole-spine MRI, were retrospectively reviewed. Dystrophic features and their relationship to the curve were recorded from radiographs. A comparison was then made between the dystrophic features evident on radiographs and adjacent soft-tissue abnormalities identified on MRI.

Dystrophic changes were documented in 16 patients on plain radiographs and in all patients on MRI. Rib pencilling was the most common finding on radiographs. In 80% of the cases with scoliosis, scalloping was seen on the concavity of the curvature. In all patients with kyphoscoliosis, scalloping was contiguous to the apex of kyphosis. Twenty-four areas of scalloping were identified on MRI. Scalloping usually developed in the concavity of the scoliotic curve or at levels unrelated to the curve. Scalloping was evident in combination with dural ectasia or neurofibroma in 15 cases. The presence of dural ectasia was confirmed in 75% of the cases of posterior scalloping and in 25% of those of lateral scalloping. The presence of neurofibromas was recognized in 25% of the cases of anterior or lateral scalloping. Dural ectasia was identified in two patients without associated scalloping. Lateral meningocoeles were not related to the development of scalloping.

Whereas posterior scalloping was commonly associated with dural ectasia, anterior and lateral scalloping were commonly the result of primary mesodermal dysplasia.