Effective management of nonconvulsive status epilepticus following cardiac surgery: a case report

Epileptic seizures following adult cardiovascular surgery occur in 0.9-3% of patients, with the condition in 3-12% of these patients progressing to status epilepticus (SE). SE is a severe condition that significantly impacts prognosis and necessitates early diagnosis and treatment. However, the diagnosis of nonconvulsive status epilepticus (NCSE) is challenging due to its subtle clinical symptoms. Herein, we report a case of NCSE that was diagnosed early by aggressive electroencephalogram (EEG) and treated effectively following cardiac surgery, resulting in discharge without sequelae.

A 44-year-old man with a history of meningitis-induced intellectual disability since childhood underwent aortic valve replacement and grafting of the ascending aorta for a bicuspid aortic valve, severe aortic regurgitation, and ascending aortic dilatation. We observed repeated tonic-clonic seizures on the day of surgery and the following day when the sedation was reduced. On the first postoperative day, an EEG revealed sharp, high-amplitude waves during the tonic-clonic seizure and 2-Hz rhythmic delta activity after motor symptoms disappeared. Based on these findings, the patient was diagnosed with NCSE. Under EEG monitoring, we initially used propofol at 4 mg/kg/h, but owing to a decrease in blood pressure, we achieved deep sedation and burst suppression by combining propofol at 1.5 mg/kg/h with midazolam at 0.18 mg/kg/h. We also administered levetiracetam and fosphenytoin as antiseizure medications. Levetiracetam was administered at 1000 mg/day and fosphenytoin at 20.5 mg/kg, followed by maintenance at 7.2 mg/kg/day. The patient's consciousness improved upon cessation of sedation on postoperative day 6. Postoperative magnetic resonance imaging revealed no abnormalities. Fosphenytoin was discontinued, and the patient was discharged on postoperative day 32 without any sequelae. The patient continues to take levetiracetam orally at a dose of 1000 mg/day and has been followed up in the outpatient clinic for 4 years without any seizure recurrence.

Postoperative seizures following cardiac surgery may occur with NCSE, even after visible seizures have ceased. This case highlights the importance of thorough EEG monitoring in cases of prolonged disturbance of consciousness, indicating that early diagnosis and treatment of NCSE can improve the prognosis.