The acute onset of lateral medullary (Wallenberg’s) syndrome in a 6-year-old boy 32 days after varicella infection is reported from the Children’s Hospital, Harvard Med Sch, Boston. He presented with headache, dizziness, nausea and vomiting, blurred vision, and a tendency to fall to the right. Signs included anisocoria (ipsilateral Horner’s sign), right ptosis, nystagmus, dysmetria, Romberg’s sign, ataxia, and hypalgesia in left leg. CT was normal but MRI showed high T2 signal in right medulla. Sequelae at 5 months were bilateral exophoria, head tilt, rotary nystagmus, and hypoesthesia of right face. 
COMMENT. The signs and symptoms together with MRI findings point to lateral medullary infarction in the distribution of the posterior inferior cerebellar artery. Vasculitis was the most likely pathology.