A 35-year-old man with a history of childhood febrile seizures presents with recurrent episodes of altered consciousness,characterized by olfactory auras, followed by impaired awareness and post-ictal confusion. His wife describes episodes where he stares blankly, makes chewing movements, and does not respond for about a minute. Afterward, he is confused and asks repetitive questions. Despite treatment with levetiracetam, carbamazepine and lamotrigine, he continues to have weekly seizures. MRI reveals hippocampal atrophy. Which of the following is the best next step in management?
