Authors :
Presenting Author: Shelly Wang, MD, MPH, FRCSC, FAANS – Nicklaus Children's Hospital
Michael Duchowny, MD – Neurologist, Brain Institute, Nicklaus Children's Hospital; Marytery Fajardo, MD – Neurologist, Brain Institute, Nicklaus Children's Hospital; John Ragheb, MD – Neurologist, Brain Institute, Nicklaus Children's Hospital
Rationale: Over the past two decades, seizures involving the insula and the peri-Sylvian region have been increasingly recognized. Data on pediatric insular epilepsy semiology, electrographic findings and surgical outcome, is limited to several small series. As a high-volume tertiary pediatric epilepsy program with an early appreciation of insular epilepsy, our center has performed increasing numbers of invasive EEG (iEEG, phase II) sampling of the insula by subdural electrodes (SDE) or stereoelectroencephalography (SEEG). We herein describe a large single-center experience with the frequency, yield, predictive variables, and outcomes of interrogation and surgery for insular epilepsy.
Methods: We retrospectively reviewed the consecutive records of children aged 21 years or under, who underwent iEEG evaluation at Nicklaus Children’s Hospital (Miami, Florida) over the past 22 years (2000 through 2022). The temporal trend, method, and yield of insular interrogation were reviewed. Information on the cohort’s demographic, clinical, electrographic and radiographic information were collected. Student’s t-test was used for sampling of means and the chi-square test of independence was used to assess the relationship between categorical variables. Cox regression analysis was performed to determine predictors of positive insular interrogation. P-values of ≤ 0.05 were considered statistically significant.
Results: We retrospectively reviewed the records of 347 consecutive phase II evaluation surgeries performed between 2000 through 2022, of which 76 (21.9%) involved insular interrogation. In this period, the insula was sampled in 22/60 SEEG implants (36.7%) and 54/287 subdural electrode implants (18.7%; p=0.01). This cohort included 35 males (46.1%) with a mean age of 5.8 ± 4.6 at seizure onset, and 12.9 ± 6.0 years at surgery. Over time, the incidence of insular interrogations has increased: the insula was involved in 13.5% of phase II evaluations prior to 2011, and 30.5% of evaluations thereafter (p< 0.001). Most commonly, patients underwent insular interrogation due to wide ictal discharges on scalp EEG (55 patients; 74.3%), followed by insular imaging abnormalities on magnetic resonance imaging (MRI), single-photon emission computerized tomography (SPECT) or positron emission tomography (46 patients; 63.0%), and suspicious insular semiology including epigastric sensation, hypersalivation, pharyngeal or laryngeal sensation, tachycardia, and facial flushing (28 patients; 38.4%). Of the patients who underwent insular interrogation, 27 patients (37.0%) yielded a positive response, leading to insular ablation by open resection or magnetic resonance-guided laser interstitial thermal therapy (MRgLITT). On multivariate logistic regression, younger age at iEEG surgery (OR 0.88, p=0.014) and insular abnormality on pre-operative SPECT, were independent predictors of positive insular sampling (OR 3.4, p=0.045).
Conclusions: Over the past 22 years, we have performed 76 insular interrogations, which consisted of 21.9% of all iEEG evaluations. Younger age and insular hyperperfusion on ictal SPECT were predictors of insular seizures.
Funding: n/a