Isolated bilateral abducent nerve palsy in infectious mononucleosis.

A 7-year-old boy presented with fever for 10 days, along with sore throat, cough, headache and occasional vomiting. A maculopapular rash developed all over the body on day-4 of illness, and on on day-8 of illness, child developed diplopia. There was no history of convulsions, altered sensorium, head trauma, or any joint pain or swelling. Examination revealed, generalized tender lymphadenopathy, hepatosplenomegaly and swelling of both upper eyelids. Neurological examination revealed bilateral lateral rectus palsy without any other cranial nerve involvement, no meningial sign, and normal size and reaction of both pupils. Investigations were: hemoglobin 9.9 g/dL, total leucocyte count 13200/mm3 (N37, L59, few atypical lymphocytes), and platelet count 152000/mm3. Liver function tests were normal. Dengue serology, malarial antigen, malaria parasite and Widal test were negative. Fundoscopy was normal. Examination of CSF showed 6 cells/ mm3 (all lymphocytes), protein 52 mg/dL and glucose 82 mg/dL. Anti-Viral Capsid antigen (VCA) IgM antibody in serum for Epstein Barr virus (EBV) was 84 mIU/mL (Normal <8 mIU/mL). Magnetic resonance imaging of brain, including angiography was normal. Child was prescribed oral Co-amoxyclav and antipyretics for 5 days. Child became afebrile by 15th day, and diplopia began to improve on seventeenth day. After 4 weeks, marked improvement of opthalmoplegia was noted.