Laser interstitial thermal therapy for insulo-opercular focal cortical dysplasia: a surgical strategy based on anatomical categorization

OBJECTIVE: The objective of this study was to propose fiber insertion strategies for MRI-guided laser interstitial thermal therapy (MRgLITT) tailored to anatomical subtypes of insulo-opercular focal cortical dysplasia (FCD), as previously defined, and to evaluate the safety and efficacy of these strategies. METHODS: The authors retrospectively reviewed patients with insulo-opercular FCD who underwent LITT at Beijing Tiantan Hospital between January 2020 and November 2024. Lesions were classified as insular, peri-insular, or opercular subtypes on the basis of anatomical criteria previously established by their group, and individualized fiber trajectories were planned accordingly. Seizure outcomes were assessed using the Engel classification. Additionally, the authors evaluated the effects of laser-induced thermal injury on adjacent motor fiber tracts and arterial structures. RESULTS: Sixteen patients (6 females) were included: 5 insular, 4 peri-insular, and 7 opercular subtypes. The median age at the time of LITT was 16 years, and 75% (12/16) of the patients underwent stereoelectroencephalography (SEEG). At a median follow-up of 2 years, 75% (95% CI 53.8%-96.2%) achieved Engel class IA outcomes. Transient neurological deficits occurred in 6 patients (37.5%, 95% CI 14.0%-61.0%), with no permanent morbidity. In insular cases, a thermal-blocking effect involving the external capsule or putamen was observed, while the posterior limb of the internal capsule remained intact. Postoperative imaging confirmed preserved perfusion of the adjacent M2-M3 segments of the middle cerebral artery (MCA), with no ischemic lesions detected on follow-up MRI. CONCLUSIONS: Fiber insertion strategies for LITT based on anatomical subtypes of insulo-opercular FCD are both safe and effective. This approach enables precise ablation of epileptogenic tissue while minimizing the risk of injury to motor fiber tracts and adjacent vasculature.