Anatomical-electroclinical phenotypes and SEEG-defined network patterns in pure insular lobe epilepsy: A study of 20...

Insular epilepsy poses significant diagnostic challenges due to its distinctive anatomical location and heterogeneous clinical manifestations. This study aims to develop a comprehensive classification system based on anatomo-electro-clinical features through stereoelectroencephalography (SEEG) analysis. The research seeks to elucidate the specific correspondence between clinical phenotypes and ictal electro-anatomical propagation patterns, investigate the network dynamics underlying various clinical phenotypes, and establish a theoretical framework for the precise diagnosis and personalized treatment of insular epilepsy.

This single-center retrospective case series included 20 patients with pure insular epilepsy confirmed by stereoelectroencephalography (SEEG) who were treated at Guangdong Sanjiu Brain Hospital between January 2015 and July 2024. The cohort comprised 12 males and 8 females with a mean age of 14.25 ± 9.8 years. All patients underwent individualized SEEG electrode implantation (mean 12.5 ± 2.3 electrodes per patient), comprehensively covering all insular subregions (anterior and posterior insula) and key brain areas in potential propagation pathways. A standardized protocol was employed for systematic analysis of: (1) ictal onset zone localization and electro-anatomical propagation patterns; (2) ictal semiology and clinical phenotype analysis based on video-SEEG recordings; and (3) surgical strategies, pathological findings, and outcome assessment (Engel classification, with follow-up periods ranging from 6 months to 8 years).

The study identified five characteristic clinical phenotypes: the BATS phenotype (35.0 %), tonic-hypermotor phenotype (25.0 %), hypermotor-autonomic phenotype (25.0 %), pure sensory phenotype (10.0 %), and pure autonomic phenotype (5.0 %). These phenotypes demonstrated specific correspondence with six distinct SEEG propagation patterns. Posterior insular epilepsy (70.0 %) preferentially propagated through sensorimotor networks, whereas anterior insular epilepsy (30.0 %) primarily spread via limbic system networks. Focal cortical dysplasia was the predominant pathological finding (94.7 %). All surgical patients (n = 19) achieved Engel Ia outcome, with follow-up periods ranging from 6 months to 8 years.

This study established an anatomo-electro-clinical classification system for insular epilepsy and elucidated the specific correspondence between clinical phenotypes and neuronal network propagation patterns. This correspondence reflects the characteristic propagation of epileptic activity through pre-existing functional connectivity networks, providing a theoretical foundation for the precise diagnosis and personalized treatment of insular epilepsy.