Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis

A 28-year-old woman with a 10-year history of focal seizures presents to the epilepsy clinic. She recalls febrile seizures at age 3, followed by a seizure-free period, then onset of impaired-awareness seizures at age 15 preceded by epigastric rising sensation and fear. Her seizures are refractory to levetiracetam and lacosamide at therapeutic doses. EEG shows the pattern marked **A** in the diagram — right anterior temporal sharp waves with phase reversal at F8/T4 electrodes. Brain MRI demonstrates right hippocampal atrophy with increased T2/FLAIR signal and loss of internal architecture on oblique-coronal cuts. Which of the following is the most appropriate next step in her management?