A12-year-oldboypresentedwith3weeksofcalfpain,tripping,andprogressiveinabilitytowalk.Theonsetwasprecededbyasorethroat4weeksprior,butnorecentimmunizationsandnosickcontacts.Hebeganhavingproblems“catchinghistoes”for2weeks.Hehadnovisual鍖椾含鐨勫摢涓尰闄㈡不鐧界櫆椋庡ソ鐨偆鐥呮不鐤楁渶濂藉尰闄?