Fig. 1 

Spinal CT manifestations in MPS IVa patients. Sagittal CT images grouped into subtypes 1 and 2 according to different levels of thoracic kyphosis apex. A MPS type IVa in a 26-year-old man (subtype 1). Sagittal reformatted spinal CT images show cervicothoracic kyphosis with apex around level of T2 (solid arrow), accompanied by square-shaped to mild central beaking of middle thoracic vertebral bodies (notched arrow). Mild thoracolumbar kyphosis with apex around level of T12 (double arrow), anterior central beaking of cervical (arrow) and visible lumbar vertebral bodies, and odontoid dysplasia (asterisk) are noted as well. B MPS type IVa in a 7-year-old girl (subtype 2). Sagittal reformatted CT images of the spine show middle thoracic kyphosis with apex around T5 (solid arrow), along with greater degrees of anterior central beaked thoracic vertebral bodies (notched arrow). Common spinal involvement of odontoid dysplasia (asterisk) with atlantoaxial instability (arrow) and associated spinal stenosis as well as thoracolumbar kyphosis (double arrow) in MPS IVa patients also well delineated by CT images