Valproic acid is one of the commonly used antiepileptic medication used for various kinds of seizure phenotypes. Although it has been known for many years about impairment of hemostasis with the use of valproic acid, there is lack of general consensus and guidelines for managing patient’s peri- and post-operative course.

44-year-old man with history of epilepsy with left mesial temporal sclerosis presented for left amygdala endoscopic laser ablation for increased frequency of seizures. Hospital course was complicated by intraoperative and post-operative intracranial bleeding requiring emergent craniotomy with hematoma evacuation. With further extension of his hemorrhage, he underwent left anterior temporal lobectomy, and left frontal external ventricular drain (EVD) placement. After two days, he had further extension of his hemorrhage and required third surgery with widening of decompressive craniotomy. After 5 months, patient was electively readmitted for cranioplasty. During this admission, his cranioplasty was complicated by epidural hematoma and abdominal site hematoma. Patient’s coagulation profile (PT, aPTT, INR, platelets count and fibrinogen level) was unremarkable before both surgeries; however, a detailed hematological evaluation revealed factor XIII deficiency with level 24% (reference range 51-163) which was possibly attributed to the valproic acid based on prior studies. (Patient has been scheduled for repeat testing of his factor XIII to confirm valproic acid as possible trigger for acquiring factor XIII deficiency).

The above case report demonstrates the importance of monitoring coagulopathic side effects in patients undergoing neurosurgical procedures while on valproic acid. There may be an underestimation of patients undergoing neurosurgical procedures while on valproic acid of those that develop coagulopathies. More studies should be performed to create a standardized protocol of monitoring coagulopathy with use of valproic acid.