A case of hyperammonaemic encephalopathy due to valproic acid.

A patient with valproic acid induced hyperammonaemic encephalopathy is presented. During chronic treatment with valproic acid this patient developed a potentially life-threatening encephalopathy without signs of liver failure. After discontinuing the valproic acid the patient recovered completely. In the case of a patient presenting with hyperammonaemic encephalopathy, the possibility of the use of valproic acid should not be overlooked.