Resident Physician University of Pittsburgh Pittsburgh, Pennsylvania, United States
Introduction: The pulvinar nucleus of the thalamus is involved in organization of posterior quadrant epilepsies and, consequently, is a potential target for neuromodulation in patients who are not candidate for resective surgery. However, interrogating thalamic structures during surgical epilepsy investigations has historically been challenging. Stereo-EEG (SEEG) that includes thalamic regions can delineate the thalamocortical organization of seizures and guide surgical decision-making at the individual level. The rationale and safety of robotic-assisted pulvinar sEEG implantation has not been described previously. Here we report on our experience with pulvinar sEEG, and two subsequent cases of pulvinar stimulation for epilepsy.
Methods: Retrospective chart review of clinical/epilepsy history, electrode implantation, rationale, and outcomes was performed for 77 patients with drug-resistant epilepsy who underwent sEEG. 30 patients (38%) underwent pulvinar SEEG implantation. To explore the pulvinar, the posterior perisylvian SEEG electrodes were extended by 2-3cm along the trajectory, with no additional electrodes implanted for mapping thalamic areas exclusively. The decision to implant thalamic regions was made in conjunction with the multidisciplinary epilepsy team. Neuromodulation candidacy was assessed with 1/50/100Hz stimulation in the pulvinar with simultaneous cortical recording.
Results: Thirty patients (ages 20-69) underwent pulvinar SEEG during intracranial monitoring. No patient developed intraparenchymal hemorrhages (IPH) related to thalamic electrodes. In all SEEG patients (N=77), three patients (3.8%) experienced post-implantation subdural hemorrhage (2 requiring evacuation) and two (2.5%) experienced IPH (none requiring intervention). Involvement of the pulvinar during ictal events (high frequency and low amplitude local field potentials) was observed in all patients with posterior quadrant epilepsies. Two patients with involvement of pulvinar areas had subsequent pulvinar neuromodulation guided by SEEG findings. One remains seizure-free at 12 months, and the other remaining seizure-free since implantation (4 months follow-up).
Conclusion : SEEG exploration of the pulvinar thalamus is a safe and can interrogate the efficacy of thalamic neuromodulation in posterior quadrant epilepsies.
