Prevalence of asymptomatic vertebral fractures in late-onset Pompe disease

Context: Bone fragility and low bone mass have been reported in small case series of patients with Pompe disease with severely reduced muscle strength or immobilization. Objective: To determine the prevalence of morphometric vertebral fractures and to evaluate bone mass in adults with late-onset Pompe disease. Design: A multicenter cross sectional observational study. The study was performed from August 2012 to December 2013. Study setting: All subjects were outpatients referred to University Referral Centers. Patients: Twenty-two late-onset Pompe disease patients with progressive proximal myopathy and minimal respiratory involvement without other diseases affecting bone mass. Main Outcome Measure: The prevalence of morphometric vertebral fractures was systematically assessed by semiquantitative analysis of the lateral spine X-ray (T4-L5). Results: A high prevalence of morphometric vertebral fractures was found. At least one vertebral fracture was present in 17 out of 22 patients (77%). All vertebral fractures were asymptomatic. Bone Mineral Density was normal in 36.5% of the patients, while 36.5% were osteopenic and 27% were osteoporotic in at least one site. Fracture prevalence was independent of muscular and respiratory functional parameters and of genotype. Conclusions: Our data show for the first time that asymptomatic and atraumatic vertebral fractures occur frequently in late-onset Pompe disease patients without a significant impairment of bone mass. Screening for asymptomatic vertebral fractures should be routinely performed in Pompe disease irrespective of the disease severity. Fracture risk should be confirmed in longitudinal studies.