Abstract: 　Objective　To explore the clinical characteristics, diagnosis and treatment of valproate inducedhyperammonemic encephalopathy (VHE) in children. Method　The clinical data of VHE developed in a child with Dravet syndrome treated by valproate were analyzed retrospectively. Results　A 6-year- and 2-month-old girl was diagnosed with Dravet syndrome at the age of 10 months. She received long-term oral administration of valproate and topiramate. The child visited for convulsive seizures this time, accompanied by consciousness disorders, significantly increased blood ammonia, abnormal liver function and severe brain impairment. Electroencephalogram showed low voltage. Cerebral magnetic resonance imaging showed diffuse edema in the cerebral hemisphere and abnormal signals in bilateral basal ganglia. After the discontinuation of sodium valproate and the treatment for lowering blood ammonia, the blood ammonia decreased, and the state of consciousness was better than before. Conclusion　Clinician should be vigilant of existence of hyperaminemia and VHE in epileptic children treated with valproate, especially in combination with topiramate, and timely treatment is needed to improve the prognosis.

Key words: sodium valproate;　hyperammonemia;　valproate induced hyperammonia encephalopathy;　Dravet syndrome