Evaluation of muscle glycogen content by 13C NMR spectroscopy in adult-onset acid maltase deficiency

Abstract

Muscle glycogen storage was measured by in vivo, natural abundance 13C nuclear magnetic resonance spectroscopy in distal and proximal lower limb segments of patients suffering from adult-onset acid maltase deficiency. Interleaved T1-weighted acquisitions of glycogen and creatine served to quantify glycogen excess. For acid maltase deficient patients ( n=11), glycogen:creatine was higher than controls ( n=12), (1.20±0.39 vs. 0.83±0.18, P=0.0005). Glycogen storage was above the normal 95% confidence limits in at least one site for 7/11 patients. The intra-individual coefficient of reproducibility was 12%. This totally atraumatic measurement of glycogen allows repeated measurement at different muscle sites of acid maltase deficient patients, despite selective fatty replacement of tissue. This could provide an additional parameter to follow the development of disease in individual patients, including in the perspective of forthcoming therapeutic trials. It may also offer an appropriate tool to study the role of glycogen accumulation in progression of the pathology.