Valproic acid as an antiepileptic drug: Is there a clinical relevance for the epilepsy surgeon?

Valproic acid (VPA) has been associated with coagulation factors deficiency, platelet dysfunction and hemorrhagic complications. We investigated 169 patients with drug resistant epilepsy (DRE), who underwent surgery, to look for clinical implications of VPA associated bleeding problems. All patients had normal preoperative coagulation profile. VPA was a part of polytherapy in 54% of patients (Group A), however 46% patients were not on VPA (Group B). The groups were comparable with mean age of 17.3±10.3years. Mean duration of surgery in group A and B were 255±70 and 250±60min respectively (p=0.26). Average blood loss in group A was 399±254 and 389±228ml in group B. (p=0.62). The percentage of total blood volume lost was 12.7% (Group A) and 17.7% (Group B) respectively (p=0.7). There were no bleeding complications in either group. Hyperammonemic encephalopathy occurred in 4 patients postoperateively requiring withdrawal or dose reduction of VPA. No mortality was recorded. We conclude that VPA does not increase clinically relevant perioperative haemorrhagic complications in patients having normal coagulation screen and platelet counts. However, hyperammonemic encephalopathy is observed in 4% of patients in perioperative period, favorably responding to discontinuation of VPA.