Polyglucosan body disease myopathy: an unusual presentation.

Polyglucosan body disease (PBD) is a slowly progressive adult-onset glycogen storage disorder that typically affects upper and lower neurons. Myopathy, as a complication of PBD has been reported rarely and clinically manifests as chronic limb-girdle muscle weakness. We report an unusual case of PBD myopathy presenting as an asymmetric motor syndrome that clinically overlapped with amyotrophic lateral sclerosis, further expanding the phenotype of this disorder.