Hand-foot-and-mouth disease and enterovirus infection — branching viva

Opening question

Examiner: Take me through this child. What is going on, and what is your frame? ^[2]

Candidate: This is enterovirus 71 brainstem encephalitis complicating hand-foot-and-mouth disease. The classic vesicular rash on day three, plus sleep myoclonus and ataxia, is the textbook early presentation of EV71 reaching the brainstem. My frame is two-layered: confirm the diagnosis and grade the neurological severity, and get this child into a monitored bed with PICU alerted, because the interval between a tremor and neurogenic pulmonary oedema can be short. I would admit, send PCR and imaging, and observe continuously. ^{[2] [5]}

Examiner: Why is this child at particular risk? ^[1]

Candidate: The burden and the mortality of EV71 fall on children under five, and especially under two, because of immature immunity, small physiological reserve and close-contact behaviours that maximise transmission. In this age group the same brainstem injury that produces myoclonus and ataxia progresses more readily to autonomic dysregulation and pulmonary oedema. The host turns a neurotropic virus into a lethal one. ^{[1] [2]}