During Surgical Evaluation of Drug-resistant Epilepsy Dense Insular Electrode Sampling Is Warranted in Cases of Suspected Insular Seizure Onset Zone
Abstract number :
1.176
Submission category :
18. Case Studies
Year :
2024
Submission ID :
1113
Source :
www.aesnet.org
Presentation date :
12/7/2024 12:00:00 AM
Published date :
Authors :
Presenting Author: Adriana Koek, MD – Kaiser Permanente
Tina Shih, MD – University of California San Francisco
Robert Knowlton, MD – Weill Institute for Neurosciences, School of Medicine, University of California San Francisco (UCSF), San Francisco, California, U.S.A.
Patrick Hullett, MD, PhD – University of California San Francisco
Rationale: Insular seizures are difficult to diagnose and may be highly disabling. In patients with drug-resistant insular epilepsy, surgical treatment represents a possibility of significant amelioration and in some cases seizure freedom. It is often underappreciated how focal insular seizures can be. In these cases, intracranial electrodes placed nearby but not directly sampling the region of ictal activity may fail to show an electrographic pattern consistent with seizure onset zone (SOZ), and may lead to the erroneous conclusion that seizures do not have an insular localization.
Methods: We present two representative cases of suspected insular epilepsy in which intracranial electrodes within the insula did not show a clear SOZ electrographic correlate. After subsequent SOZ mapping with electrical stimulation further supported an insular localization, additional insular electrodes were placed to permit denser sampling and more accurate identification of the SOZ.
Results: With additional electrode sampling, an insular SOZ was found in both cases and subsequent insular resection resulted in seizure freedom.
Conclusions: It is often underappreciated how focal seizures can be in the insula. In some cases, this focality can lead to an electrographic ictal correlate which is misleading or entirely absent after placement of intracranial insular electrodes, resulting in incorrect or nondiagnostic localization results. If insular localization is high on the differential, we favor sampling dorsal and ventral (anterior, mid, and posterior) insula at a minimum. If an insular ictal correlate is still not appreciated, SOZ mapping can be a helpful tool to assess if additional electrodes are warranted for definitive localization.
Funding: None
Case Studies