Valproate-Induced Hyperammonemic Encephalopathy Successfully Treated With Levocarnitine in an Elderly Patient Without Liver Dysfunction

An 87-year-old male with a history of seizure disorder on long-term prophylaxis with valproate and concomitant levetiracetam presented with impaired consciousness and anorexia. The evaluation revealed a markedly elevated blood ammonia level of 518 μmol/L and decreased serum carnitine levels, leading to a diagnosis of valproate-induced hyperammonemic encephalopathy in the absence of liver dysfunction. Discontinuation of valproate, continuation of levetiracetam, and initiation of levocarnitine supplementation and branched-chain amino acid infusion resulted in a durable resolution of symptoms. This case underscores the importance of promptly considering valproate-induced hyperammonemic encephalopathy due to carnitine depletion in patients on long-term valproate therapy who develop acute encephalopathy and initiating levocarnitine treatment for effective management.