Severe muscle damage following viral infection in patients with Fukuyama congenital muscular dystrophy

Fukuyama congenital muscular dystrophy (FCMD), which is characterized by cortical migration defect and eye abnormalities, is the most common subtype of CMD in Japan. Fukutin (FKTN), the responsible gene for FCMD, encodes a protein involved in the glycosylation of alpha-dystroglycan. We have experienced some patients with FCMD who showed sudden exacerbation of muscle weakness with marked elevation of serum creatine kinase (CK) and urinary myoglobin levels a few days after a febrile episode of viral infection, occasionally leading to death. To describe this peculiar phenomenon, we focused on 12 patients who developed a sudden exacerbation of muscle weakness among 96 genetically defined FCMD patients and hospitalized because of a febrile illness at Tokyo Women’s Medical University between 1997 and 2008. All the 12 patients were homozygous for a 3-kb insertion mutation of FKTN. The patients developed exacerbation of muscle weakness ranging from paralysis to loss of head control. The onset was concentrated in summer, and coxsackieviruses and enteroviruses were most often detected, especially in infantile patients. Eight of the 12 patients were treated with corticosteroids and recovered within 2 weeks. Four patients were treated without steroid, and needed 18.5 days on mean for improvement. None developed renal failure. The reason for muscle damage induced by viral infection remains unknown; however, physicians should consider its risk, sometimes leading to death, and draw it to parents’ attention, especially in the defervescent stage.