Whole‐Body Muscle Magnetic Resonance Imaging in Glycogen‐Storage Disease Type III

Abstract

Introduction: The main objective of this study was to describe muscle involvement on whole‐body magnetic resonance imaging scans in adults at different stages of glycogen‐storage disease type III (GSDIII). Methods: Fifteen patients, 16–59 years of age, were examined on a 3‐T system. The examinations consisted of coronal and axial T1‐weighted images or fat images with a Dixon technique, and were scored for 47 muscles using Mercuri's classification. Muscle changes consisted of internal bright signals of fatty replacement. Results: Distribution across muscles showed predominant signal alteration in the lower limbs and postural muscles. This finding is consistent with the overall clinical presentation of GSDIII and the results of heatmap scores. Review of the MRI scans provided new information regarding recurrent muscle changes, particularly in the soleus, gastrocnemius medial head, and thoracic extensor muscles. Discussion: Whole‐body muscle imaging provides clinically relevant information regarding muscle involvement in GSDIII. A severity score may contribute to improved patient management. Muscle Nerve, 2019

The Novel Compound Heterozygous Mutations in the AGL Gene in a Chinese Family With Adult Late-Onset Glycogen Storage Disease Type IIIa

“…Very few studies have investigated muscle MRI findings in patients with GSD IIIa. Two previous studies demonstrated edema and fat degeneration in the muscle fibers located in the posterior compartment of the lower limbs in patients with GSD IIIa (9,10). Our case also found the similar results.…”

Narrative review of glycogen storage disorder type III with a focus on neuromuscular, cardiac and therapeutic aspects

“…Further research into this is necessary, especially given that MRI studies do suggest a correlation in severity and pattern between fatty replacement in skeletal muscle and clinical symptoms. 29 Recently, arguments in favor of enhanced but potentially dysregulated autophagy have emerged. One study noted the presence of glycogen laden vacuoles with a double membrane and features suggesting that they are autophagosomes, as well as protein markers suggesting increased autophagy.…”

“…In the literature, only three GSD IIIa patients with bulbar muscle dysfunction (dysarthria and deglutition disorder) are reported 52 . In the cohort reported by Tobaly and colleagues, two patients out of 15 had moderate but significant impairment of forced vital capacity, at 66% and 52% of predicted values, 29 clinically presenting with dyspnea on exertion, and it has to be noted that those patients presented a severe generalized myopathy. Severe respiratory muscle involvement is even rarer and only one case has been reported, namely a 47‐year‐old woman who developed a subacute severe myopathy of the respiratory muscles after a 3‐week period of strict fasting 53 .…”

“…Although no correlation between clinical severity and degree of vacuolar myopathy has been established in pathological studies, 13,39 those have generally been lacking in the clinical data and prospective observation required to establish such a correlation. Further research into this is necessary, especially given that MRI studies do suggest a correlation in severity and pattern between fatty replacement in skeletal muscle and clinical symptoms 29 …”

“…Recently, Tobaly and colleagues 29 analyzed 15 patients aged 16 to 59 years old and described several characteristics helpful to distinguish GSD III from other myopathies. Like the Wary and colleagues study, 37 there was an almost perfectly symmetrical presentation but, notably, there was more severe involvement of the distal muscles, which showed essentially fat replacement but without severe muscle atrophy.…”