Advancing intraoperative brain mapping: First-in-human evaluation of flexible high-density electrocorticography grids for epilepsy surgery

Mapping epileptiform activity, specifically high frequency oscillations (HFOs), with intraoperative electrocorticography (ECoG) may guide epilepsy surgery. The most relevant recording takes place following the surgical resection to identify any residual epileptic activity. Recording HFOs is, however, challenging due to their focal and low-amplitude nature. We designed and evaluated a novel soft, flexible, and stretchable high-density electrode grid (SOFT ECoG) tailor-made for epilepsy surgery to enhance HFO detection and enable recordings from within resection cavities. In this first-in-human evaluation of flexible high-density grids, we recorded with the SOFT ECoG grids and standard rigid high-density grids in three patients. Both grids were sequentially placed on the same cortical area and recorded similar interictal epileptiform activity (spikes and HFOs). Crucially, the SOFT ECoG grid's pliability enabled recording from relevant, but anatomically challenging, areas like the resection cavity. This was exemplified in one patient, where the SOFT ECoG identified epileptiform activity (spikes and HFOs) within a resection cavity revealing remnant epileptic tissue needing removal. This area was inaccessible to the standard rigid grid. These findings demonstrate the potential of novel flexible electrode grids to enhance intraoperative mapping of epileptiform activity including HFOs in areas inaccessible with standard rigid grids, thereby improving epilepsy surgery guidance.