A child with benign acute childhood myositis after influenza

Benign acute childhood myositis (BACM) is a rare transient muscle syndrome classically occurring in children after a viral upper respiratory infection (URI). BACM causes difficulty walking due to severe bilateral calf pain. The incidence of this well-described phenomenon is uncertain but infrequent, and it is typically appreciated during times of large influenza outbreaks and epidemics. The URI symptoms that precede BACM are consistent with an uncomplicated viral influenza infection and include fever, malaise, cough, sore throat, headache, and rhinitis.

Little is written in the Emergency Medicine literature regarding this clinical entity. In this report, a brief review of BACM from the current literature is provided, as well as tools to aid in differentiating it from more severe but similar disorders such as rhabdomyolysis and Guillain-Barré syndrome.

We present a case of BACM in a 7-year-old boy who presented to the emergency department after a resolving URI with the acute onset of calf pain causing alarming difficulty in his ability to walk. His presentation was typical for BACM and his condition improved with supportive treatment.

Although quite alarming and potentially puzzling to the physician who is not familiar with BACM, this syndrome is self limited and spontaneously resolves with no specific intervention. Recognition of this rare but distinct clinical entity by the emergency physician can spare a patient from potentially unneeded invasive testing and hospital admission.