Re-evaluating impaired consciousness in temporal lobe epilepsy: The role of language dominance and network...

Temporal lobe epilepsy (TLE) frequently affects clinically-classified ictal consciousness, which the 2025 International League Against Epilepsy (ILAE) classification operationalizes through clinical assessment of awareness and responsiveness. It remains uncertain whether the spatial lateralization between the seizure-onset zone and the language-dominant hemisphere is associated with this classification.

We retrospectively analyzed 40 adults with TLE who underwent video-electroencephalography (EEG) evaluation and language-task functional magnetic resonance imaging (fMRI). Seizures were classified as focal with preserved consciousness (FPC) or focal with impaired consciousness (FIC). Patients were grouped as ipsilateral (seizure onset ipsilateral to language dominance) or contralateral. The primary analysis utilized Bayesian beta-binomial estimation, alongside secondary whole-brain functional network connectivity (FNC) comparisons.

Of 40 patients, 27 (67.5%) experienced FIC and 13 (32.5%) experienced FPC. FIC occurred in 86.7% of ipsilateral (13/15) patients compared to 56.0% of contralateral (14/25) patients. Bayesian estimation yielded a 97.4% posterior probability of a directional association between ipsilateral onset and a higher rate of FIC, although the magnitude carries considerable uncertainty (posterior median odds ratio [OR] = 4.10, 95% credible interval [CI]: .98-21.20). Absolute laterality index did not differ between FIC and FPC groups (Mann-Whitney U = 230, p = .115). Compared with healthy controls, FPC patients showed widespread FNC differences, whereas no significant control differences were detected in FIC patients. However, direct FIC-FPC comparisons did not reveal significant global task-evoked FNC differences.

Bayesian estimation supported an association between ipsilateral seizure onset relative to the language-dominant hemisphere and a higher probability of FIC classification. The absence of detectable task-evoked FNC differences between FIC and FPC patients did not provide evidence for clearly separable interictal language-network architectures.