Background: Refractory seizures sometimes arise from deeper foci within the brain. When difficult to detect on scalp EEG, chances of successful epilepsy surgery are reduced. Two patients had scalp Electroencephalogram (EEG) negative seizures, got intracranial EEG and did well with responsive nerve stimulation (RNS). Patient consent was obtained to utilize these cases for educational purposes. Cases: Patient I is a 29-year-old female, with prior right temporal lobectomy, s/p vagal nerve stimulation (VNS) and 5-year seizure freedom before recurrence. Magnetic resonance imaging (MRI) and positron emission tomography (PET) showed signs of prior surgery. Scalp EEG and Magnetoencephalogram (MEG) were unremarkable. Neuropsychological testing showed diminished core verbal function and memory. Intracarotid amobarbital procedure (IAP)/Wada testing revealed left dominance for language and memory. Stereotactic EEG (sEEG) captured focal impaired awareness seizures and focal aware seizures with early involvement of the right posterior cingulate (RPC) and right posterior insular (RPI) regions. Brain mapping/cortical stimulation revealed motor function in RPC and sensory in RPI regions precluding resection/ laser ablation. RNS implantation in the RPC and RPI regions achieved seizure freedom 4 months after implantation. Patient II is a 33-year-old female, who would wake up, laugh/curse, vocalize and show left (focal) predominant hyper motor movements progressing to tonic-clonic convulsion. MRI brain showed a venous angioma. PET revealed decreased uptake in right posterior parasagittal frontal and right inferior parasagittal frontal regions. MEG was unremarkable. Neuropsychological testing showed weak bi-frontotemporal systems. Wada testing showed left dominance for language and memory. SEEG captured hyper motor seizures with early involvement of right orbito frontal (ROF) with spread to right hippocampal (RH) regions. RNS implantation in the ROF and RH regions achieved 30% seizure reduction 3 months post implantation.
Scalp negative seizures, Scalp EEG, Stereotactic EEG, Deep epileptic foci, Medically refractory epilepsy