OBJECTIVES : To gain insight into the frequency, age of onset, and management of cervical cord compression in mucopolysaccharidosis VI (MPS VI). METHODS : Cervical spine magnetic resonance imaging (MRI) data and/or cervical decompression surgery data collected between 30 June 2005 and 1 September 2015 were analyzed from subjects enrolled in the MPS VI Clinical Surveillance Program (CSP) (ClinicalTrials.gov : NCT00214773), an ongoing multicenter, observational, retrospective and prospective registry. RESULTS : Of 213 subjects enrolled in the CSP, 134 (62.9%) had at least one documented cervical spine MRI assessment. An additional four subjects were identified through s MRI. In general, subjects with cervical cord compression had significantly lower height Z-scores compared to those without cervical cord compression (p b 0.0001); nevertheless, a few subjects of taller stature had documented cervical cord compression at a young age. Most subjects >20 years of age (31/33, 93.9%) presented with cervical cord compression. There was an insufficient number of subjects with both pre- and post-enzyme replacement therapy (ERT) MRI data to determine any association between ERT and cervical cord compression. Surgical decompression was performed on 58 subjects (42.0%), with mean age at first surgery of 13.1 years. Decompression plus stabilization procedures accounted for 12.1% of surgeries. Eight subjects (13.8%) underwent reoperation. Complications during or following surgery were reported in 3 subjects, with anesthesia-related complications resulting in two deaths. CONCLUSIONS : All individuals with MPS VI are at high risk of developing cervical cord compression at an early age.
Routine MRI assessments should be initiated from the time of MPS VI diagnosis. The perioperative management of MPS VI patients can be challenging. This study contributes to the understanding of the natural history of MPS VI.