Abstracts

Rationale: Case reports of previously documented insular seizures describe gustatory auras, viscera-sensitive or somatosensory complaints. Isnard et al. suggests a clinical sequence that can be used to identify Insular Lobe Epileptic Seizures, as events without impairment of consciousness associated with sensations of discomfort (laryngeal, thoracic, or abdominal), unilateral paresthesias, and/or dysphonic or dysarthric speech, followed my focal somatomotor manifestations (Isnard J, Guenot M, et al. Epilepsia 2004). The vast connectivity between the Insula, frontal and temporal lobe contributes to involvement of several structures and networks resulting in a variety of presenting symptoms. Microsurgical approach using stereotactic placement of depth electrodes has allowed surgeons to place electrodes with less risk of disrupting vascular supply and more accurate characterization of seizure foci and spreadMethods: Our surgical database was reviewed from January 2010 to April 2015, for cases in whom depth electrodes were placed in the insula. 28 patients had depths placed (ages 4-20 years) after extensive phase 1 investigative studies and all subsequently underwent Epilepsy Surgery. Electronic medical records were reviewed including outpatient evaluation, inpatient EMU monitoring, pre and post-op surgical reports, and clinic follow up. Scalp EEG and imaging related to pre-surgical workup (MEG or SPECT scans) along with intracranial electrode monitoring reports were reviewed. Surgical discharge summaries and most recent clinic follow up notes were used to determine Engel Classification. 10 patients did not show sufficient evidence of insular involvement necessitating specific resection of the insula. Five patients were excluded secondary to extensive disconnections or hemipherotomies. The remaining 13 patients had established insular involvement with resultant partial or complete resection or ablation along with resection of adjoining foci.Results: All 13 patients were noted to have epileptogenic zones extending to areas outside of the Insula. Most patients had previous surgeries that were unsuccessful. All patients have demonstrated a worthwhile improvement after 12-60 month follow up with 9 (70%) becoming completely free of disabling seizures, according to Engel Classification. 40% (5/13) required inpatient or outpatient rehab immediately after their hospital stay. All, but two patients, made full recovery in strength and function with appropriate therapies, and all patients are ambulatory. Interestingly, the two patients who underwent thermal ablation without open craniotomy did not have any post-surgical deficits.Conclusions: The majority of our patients had insula plus syndromes with another lobe also involved. The majority had prior surgeries with the Insula missed secondary to poor prior sampling. The frontal lobe was the region maximally involved in the cases with insula involvement. Outcome suggests that insula sampling may improve seizure outcome, especially in cases of prior surgeries, or cases difficult to localize with rapid diffuse spread on scalp EEG.