Hyperammonemia induced by prophylactic administration of antiepileptic drugs during the perioperative period of craniotomy

• Over 70% patients in neurosurgery using antiepileptic drugs develop hyperammonemia.
• Valproate has the greatest impact on blood ammonia and liver synthetic function.
• Carbamazepine may be a proper choice for the majority of neurosurgery patients.
• Valproate is more appropriate for patients with elevated liver transaminases.
• Blood ammonia and liver function should be routinely monitored in these patients.

BackgroundAntiepileptic drugs (AEDs) are increasingly used prophylactically during the perioperative period to prevent epilepsy in patients undergoing craniotomy. Evidence concerning the use of AEDs and the incidence, extent and risk factors of hyperammonemia induced by different types of AEDs is lacking.MethodsPatients were divided into groups with 3 different AED regimens, levetiracetam, valproate and carbamazepine regimens, and the blood ammonia concentration and liver and coagulation functions were assessed during the perioperative period.ResultsSixty-five patients were enrolled consecutively and the postoperative hyperammonemia was found in 46 patients (70.77%), and 45 (97.83%) were asymptomatic. A total of 80.95% of the patients using valproate developed hyperammonemia, and the postoperative blood ammonia concentration continued to rise in 61.90% of these patients. Additionally, valproate had the least impact on liver enzymes. The synthetic function of the liver in patients with higher concentrations of preoperative blood ammonia was more seriously damaged than that in patients with normal postoperative ammonia concentrations.ConclusionsSelection of AED for patients undergoing craniotomy should be based on the individual medical situation. Carbamazepine may be a proper choice for the majority of these patients, while valproate is likely to be more appropriate for patients with abnormal liver aminotransferases.