Intracranial EEG and laser interstitial thermal therapy in MRI-negative insular and/or cingulate epilepsy: case series

Abstract

OBJECTIVE The goal of this study was to assess the success rate and complications of stereo-electroencephalogra-phy (sEEG) and laser interstitial thermal therapy (LITT) in the treatment of nonlesional refractory epilepsy in cingulate and insular cortex. METHODS The authors retrospectively analyzed the treatment response in 9 successive patients who underwent insular or cingulate LITT for nonlesional refractory epilepsy at their center between 2011 and 2019. Localization of seizures was based on inpatient video-EEG monitoring, neuropsychological testing, 3-T MRI, PET scan, magnetoencephalography scan, and/or ictal SPECT scan. Eight patients underwent sEEG, and 1 patient had implantation of both sEEG electrodes and subdural grids for localization of epileptogenic zones. LITT was performed in 5 insular cases (4 left and 1 right) and 3 cingulate cases (all left-sided). One patient also underwent both insular and cingulate LITT on the left side. All of the patients who underwent insular LITT as well as 2 of the 3 who underwent cingulate LITT were right-hand dominant. The patient who underwent insular plus cingulate LITT was also right-hand dominant. RESULTS Following LITT, 67% of the patients were seizure free (Engel class I) at follow-up (mean 1.35 years, range 0.6–2.8 years). All patients responded favorably to treatment (Engel class I–III). Two patients developed small intracranial hemorrhages during the sEEG implantation that did not require surgical management. One patient developed a large intracranial hemorrhage during an insular LITT procedure that did require surgical management. That patient experienced aphasia, incoordination, and hemiparesis, which resolved with inpatient rehabilitation. No permanent neurological deficits were noted in any of the patients at last follow-up. Neuropsychological status was stable in this cohort before and after LITT. CONCLUSIONS sEEG can be safely used to localize seizures originating from insular and cingulate cortex. LITT can successfully treat seizures arising from these deep-seated structures. The insula and cingulum should be evaluated more frequently for seizure onset zones.

Probabilistic comparison of gray and white matter coverage between depth and surface intracranial electrodes in epilepsy

“…Nearly all the depth electrode cases had some coverage of the insula or cingulate. Though insular and cingulate cortex epilepsies are rare, nonlesional insular and cingulate epilepsies are difficult to diagnose and may be misdiagnosed as temporal lobe epilepsy or frontal lobe epilepsy without utilization of depth electrodes in those regions 34 , 35 . Depth electrodes therefore provide a significant advantage in sampling the insula and cingulate, even if those regions may not be a part of the initial localization hypothesis.…”

Laser interstitial thermal therapy for the treatment of insular lesions: A systematic review

“…Around one third of the patients experienced a temporary paresis. Gireesh et al, reported one intracerebral hematoma following LITT that required a decompressive hemicraniectomy, but subsequently had a good outcome ( 26 , 34 ). Bouthillier et al, recently published the results of 44 insulo-opercular cortectomies in 43 patients achieving a an Engel class 1 outcome in 77% (mean follow-up 6 years) with a 7% permanent postoperative deficit.…”

“…Recently, through a wider use of stereotactic electroencephalography (SEEG), insular epilepsy has been recognized as a separate diagnostic entity ( 23 ). Insular LITT was used for the treatment of epileptic lesions both in pediatric and adult cohorts ( 24 – 26 ). Laser interstitial thermal therapy compares favorably with other minimally invasive therapies for the treatment of drug resistant epilepsy (DRE), such as radiofrequency thermocoagulation (RFTC) with SEEG electrodes and gamma knife surgery (GKS) ( 23 , 26 ).…”

Volume-Based Radiofrequency Thermocoagulation for Pediatric Insulo-Opercular Epilepsy: A Feasibility Study

“…Recently, many studies have focused on LITT for insular epilepsy. [36][37][38][39][40] LITT may be a better option, but volume-based RFTC is still a valuable alternative if LITT is not available. The laser probe with a diameter of 1.6 or 3.3 mm is used for LITT, and a cylindrical lesion is formed around the trajectory.…”