Encefalopatía hiperamoniémica por ácido valproico

Abstract

One of the less frequent idiosyncratic side effects of valproic acid (VPA) is encephalopathy. Here we report one case. An 83-year-old female with no relevant past history, who received treatment with VPA following a post-traumatic subarachnoid haemorrhage and two convulsive seizures. A few days later, she was admitted to the Emergency Department because of a progressive clinical picture of mental slowness, nauseas and apathy. The systemic examination was normal. Neurologically, the most striking features were inattention and disorientation, despite her having a good level of consciousness, and mental confusion. Levels of VPA were within the below-therapeutic range and the basic lab findings (including hepatic profile) were normal, except for hyperammonaemia. Neuroimaging studies and cerebrospinal fluid analysis were also normal. An electroencephalogram (EEG) showed signs of severe diffuse encephalopathy with slow, triphasic waves and a non-convulsive epileptic status was therefore ruled out. After withdrawing the VPA, the patient's condition improved until her basal situation was reached in 48 hours and the EEG became normal, as did her ammonium levels. When faced with a patient who has recently been taking VPA and who presents a clinical picture of mental confusion, the possibility of encephalopathy due to said drug must be taken into consideration.