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

Background Odontoid dysplasia is recognized as a major component of the con stellation of dysostosis multiplex lesions associated with Hurler's syndrom e (MPS 1H). Because of this abnormality, there is an increased risk of atla ntoaxial subluxation with potential cervical spinal cord injury. A signific ant alteration of the natural history of the disease with respect to the vi sceral, cardiac, and skeletal systems has resulted in an increased Life spa n for MPS 1H patients associated with engraftment from normal donors. Objective. The purpose of this study was to evaluate the longitudinal chang es of odontoid dysplasia in MPS 1H following engraftment From bone-marrow t ransplantation (BMT). Materials and methods. A retrospective review of sequential plain film or c ervical spine MR was performed in patients with MPS 1H. Odontoid morphology was graded as aplasia, severe dysplasia, moderate dysplasia, mild dysplasi a, or normal. Odontoid morphology was plotted against the time interval. Fu lly engrafted, nontransplanted, and partially engrafted patients had carefu l imaging evaluation of the odontoid process. Results. Ten patients were studied with a mean interval follow-up of 8.7 ye ars post-BMT. Seven patients were totally engrafted. Two patients were nont ransplanted, and one patient had only partial engraftment (20 % enzyme acti vity). All totally engrafted patients had a progressive improvement in the grade of odontoid dysplasia following BMT. Patients with partial engraftmen t or without transplantation demonstrated static or increasing odontoid dys plasia. 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 a ssociated with significant change in the appearance of the upper cervical s oft-tissue masses. Conclusion. For the first time, this report documents that patients with MP S 1H show a decrease in the degree of odontoid dysplasia on imaging after s uccessful engraftment following BMT.