Evaluation of spinal involvement in children with mucopolysaccharidosis VI: the role of MRI.

OBJECTIVE: To evaluate spinal MRI features of mucopolysaccharidosis (MPS) VI and to assess the correlation with clinical findings.

METHODS: We retrospectively evaluated spinal MRI scans and clinical findings at the time of imaging in 14 patients (8 male, 6 female) with MPS VI. Craniometric measurements were performed and the images were assessed for bony anomalies, spinal stenosis and spinal cord compression. The degree of cervical cord compression was scored and correlated with neurological examination findings at the time of imaging. Vertebral alignment, structural changes in spinal ligaments and intervertebral discs were also assessed.

RESULTS: All patients had cervical stenosis due to bony stenosis and thickened retrodental tissue (median: 6.05 mm, range 3.3-8 mm). Retrodental tissue thickness was found to increase with age (p = 0.042). Compressive myelopathy was detected at upper cervical level in 11 (79%) and lower thoracic level in 2 patients (14%). Significant inverse correlation was found between cervical myelopathy scores and neurological strength scores. The most common bony changes were hypo/dysplastic odontoid; cervical platyspondyly with anterior inferior beaking; thoracic posterior end plate depressions and lumbar posterior scalloping. Kyphosis due to retrolisthesis of the beaked lumbar vertebrae and acute sacrococcygeal angulations were other remarkable findings.

CONCLUSION: MRI is an essential component in evaluation of spinal involvement in MPS VI, and scanning of the entire spine is recommended to rule out thoracic cord compression. Advances in knowledge: This study provides a detailed description of spinal MRI findings in MPS VI and underlines the role of MRI in management of cord compression.