Responsive Neurostimulation for Management of Refractory Precuneus Onset Epilepsy: A Case Report

Posterior quadrant epilepsy is relatively uncommon and refractory seizures from these regions are difficult to diagnose and manage. A 28-year-old woman presented for evaluation of her seizures. Scalp Electroencephalogram (EEG) showed seizures with independent onset over the right posterior and left anterior regions. Positron emission tomography (PET) scans revealed multiple regions of hypometabolism in the brain with maximum decrease in metabolism seen over the left and right precuneus and both occipital lobes. Magnetoencephalography (MEG) revealed epileptogenic dipoles over bilateral precuneus regions. Intracranial EEG revealed seizure onset from the left precuneus and left frontal regions with rapid generalization. She underwent Responsive Neurostimulation System (RNS) implantation targeting the left precuneus and left frontal regions for network modulation. She has had a 90 percent seizure reduction and remains on 2 medications as she continues to follow up in clinic. Posterior quadrant epilepsy remains a challenging condition to manage, and the use of neuromodulation may improve response rates and improve our understanding of these networks. Definite guidelines on location of electrode placement of RNS in such cases remain absent and improved understanding of such seizure networks is expected to improve our ability to target therapeutic nodes accurately to achieve greater seizure control.