Correction of odontoid dysplasia following bone-marrow transplantation and engraftment (in Hurler syndrome MPS 1H)

Background Odontoid dysplasia is recognized as a major component of the constellation of dysostosis multiplex lesions associated with Hurler's syndrome (MPS 1H). Because of this abnormality, there is an increased risk of atlantoaxial subluxation with potential cervical spinal cord injury. A significant alteration of the natural history of the disease with respect to the visceral, cardiac, and skeletal systems has resulted in an increased Life span for MPS 1H patients associated with engraftment from normal donors. Objective. The purpose of this study was to evaluate the longitudinal changes of odontoid dysplasia in MPS 1H following engraftment From bone-marrow transplantation (BMT). Materials and methods. A retrospective review of sequential plain film or cervical spine MR was performed in patients with MPS 1H. Odontoid morphology was graded as aplasia, severe dysplasia, moderate dysplasia, mild dysplasia, or normal. Odontoid morphology was plotted against the time interval. Fully engrafted, nontransplanted, and partially engrafted patients had careful imaging evaluation of the odontoid process. Results. Ten patients were studied with a mean interval follow-up of 8.7 years post-BMT. Seven patients were totally engrafted. Two patients were nontransplanted, and one patient had only partial engraftment (20 % enzyme activity). All totally engrafted patients had a progressive improvement in the grade of odontoid dysplasia following BMT. Patients with partial engraftment or without transplantation demonstrated static or increasing odontoid dysplasia. MR imaging showed abnormal dural soft-tissue masses at the level of C2 in all patients. Reduction in the grade of odontoid dysplasia was not associated with significant change in the appearance of the upper cervical soft-tissue masses. Conclusion. For the first time, this report documents that patients with MPS 1H show a decrease in the degree of odontoid dysplasia on imaging after successful engraftment following BMT.