Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 52 4 2014 04 15 327 330 EN Behdad Gharib Department of Pediatrics, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran. Mahmood Reza Ashrafi Department of Pediatrics, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran. Ali Tavassoli Department of Pediatrics, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran. Firozeh Hosseini Department of Pediatrics, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran. Hossein Farshadmoghadam Department of Pediatrics, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran. 2015 10 11 In this case we present a previously healthy child with sudden behavioral change and acute confusional state (ACS). ACS is a neurologic emergency. The clinical manifestations of ACS are; confused affect, limited verbal response, disturbance in performing orders, some automatism, stable vital signs and absence of tonic-clonic movements and it has a wide range of differential diagnosis which should be assessed by detailed medical history, medical examination and laboratory tests. The only abnormal test found in this patient, was cerebrospinal fluid abnormality, consistent with viral encephalitis. https://acta.tums.ac.ir/index.php/acta/article/view/4631 https://acta.tums.ac.ir/index.php/acta/article/download/4631/4390