[Neurologic effects of acyclovir after an allogenic marrow graft]

On the 4th day of acyclovir treatment for Herpes simplex pneumonia, a 28 month-old girl who had received allogenic marrow transplant for stage IV neuroblastoma presented with severe neurologic disorders including coma and choreic movements. These symptoms disappeared 9 days after acyclovir was stopped. The disturbance in acyclovir kinetics because of acute renal failure and/or a cerebral cortex atrophy might explain the poor neurologic tolerance of acyclovir. This reversible neurologic involvement on a prone patient should be known as a differential diagnosis of Herpes simplex encephalitis.