Severe axial myopathy in McArdle disease.
OBJECTIVE
McArdle disease is a nonlysosomal glycogenosis that classically manifests with exercise-induced pain from childhood. Fixed weakness may occur from the fifth decade and is typically mild and located around the shoulder girdle.


METHODS
We describe a 61-year-old man with exercise-induced pain from a young age and a 3-year history of weight loss and an elevated creatine kinase level up to 4000 U/L. On examination, he was severely atrophic and weak in his shoulder girdle and the entire paraspinal musculature. Magnetic resonance imaging confirmed that the paraspinal musculature was completely converted to fat. A muscle biopsy specimen was myopathic with a lack of myophosphorylase and multiple large vacuoles with glycogen. A nonischemic forearm test demonstrated a lack of increase in lactate together with an exaggerated ammonium elevation. Genetic testing verified the suspicion of McArdle disease.


CONCLUSIONS
This is a highly atypical presentation of McArdle disease with severe paraspinal wasting and weakness. We suspect that this is related to the unusual amount of glycogen vacuoles and stress the importance of including McArdle disease in the differential diagnosis of axial myopathy.
Neuromuscular Research Unit, Department of Neurology, Blegdamsvej, Copenhagen, Sealand, Denmark.
Nanna
N
Witting
Department of Clinical Genetics, University of Copenhagen, Copenhagen, Denmark.
Morten
M
Duno
Laboratoire des Maladies Héréditaires du Métabolisme et Dépistage Néonatal, Centre de Biologie Est, Hospices Civils de Lyon, Lyon, France.
Monique
M
Piraud
Neuromuscular Research Unit, Department of Neurology, Blegdamsvej, Copenhagen, Sealand, Denmark.
John
J
Vissing
D003937:Diagnosis, Differential; D006012:Glycogen Storage Disease Type V / Q000150:complications* / Q000175:diagnosis* / Q000235:genetics; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000175:diagnosis* / Q000209:etiology* / Q000235:genetics; D012720:Severity of Illness Index