Trunk muscle involvement in late-onset Pompe disease: study of thirty patients.

Late-onset Pompe disease is characterized by progressive weakness involving proximal limb and respiratory muscles. Recently, treatment with enzyme replacement therapy (ERT) has been introduced partially improving patients' prognosis, but a standard consensus on when to start ERT is still lacking. There is also a lack of biomarkers related to the clinical progression of the disease. Here we used muscle magnetic resonance imaging (MRI) or computed tomography (CT) to study the abdominal and paravertebral muscles of 30 late-onset Pompe patients at different stages of disease. We observed a selective pattern of muscle damage, with early involvement of the Multifidus muscle, followed by the Obliquus internus abdominis and Longissimus muscle. Some degree of trunk involvement on MRI occurred even in asymptomatic patients. Severity of muscle involvement in MRI correlated with patients' functional stage. We suggest that: (a) the combination of paravertebral and abdominal muscle involvement may serve as a useful tool in the diagnostic work-up of patients with a clinical suspicion of Pompe disease; (b) trunk abnormalities appear at very early stages of disease and even in asymptomatic patients, possibly "announcing" the onset of the disease and thus the need for a closer clinical follow-up.