PRES leading to the diagnosis of McArdle disease

A 35 year-old male developed myalgias after moving furniture and was hospitalized with acute renal failure and rhabdomyolysis requiring hemodialysis. He then had several generalized tonic-clonic seizures. Brain MRI showed findings of posterior reversible encephalopathy syndrome (PRES). Interval history revealed easy fatigability and exercise-induced myalgias in childhood but no preceding history of urine discoloration. Quadriceps biopsy showed absent muscle myophosphorylase reactivity consistent with the diagnosis of McArdle disease. With supportive care he improved and the PRES resolved. This case represents an extreme in the spectrum of complications that can occur in McArdle disease, including downstream central nervous system involvement and highlights the importance of early recognition and aggressive management of rhabdomyolysis.