Preserved ictal responsiveness in right mesial temporal lobe epilepsy: metabolic correlates in posterior temporal networks with FDG-PET

Front Neurol. 2025 Oct 23;16:1690510. doi: 10.3389/fneur.2025.1690510. eCollection 2025.

ABSTRACT

OBJECTIVE: Automatisms with preserved responsiveness (APR) represent a distinctive clinical feature in right mesial temporal lobe epilepsy (MTLE). This study aimed to investigate whether interictal FDG-PET hypometabolism correlates with impaired responsiveness during seizures.

METHODS: We retrospectively analyzed 49 patients with right MTLE who underwent presurgical evaluation. Patients were stratified into APR+ (n = 16) and APR- (n = 33) groups based on a standardized four-domain assessment (orientation, memory, verbal command, motor execution). Interictal FDG-PET hypometabolism was visually scored on a three-point scale (0 = absent, 1 = moderate, 2 = severe) across 31 predefined brain regions by three blinded epileptologists. Group comparisons were performed using independent-sample t tests or Mann-Whitney U tests, with Bonferroni correction (p < 0.0016) and effect size estimation (Cohen’s d).

RESULTS: APR- patients exhibited significantly greater hypometabolism in the posterior lateral temporal cortex (p = 0.00061, Cohen’s d = 1.20) compared to APR+ patients. Although hypometabolic trends were also observed in posterior mesial (p = 0.00203) and posterior basal temporal regions (p = 0.00328), these did not survive multiple-comparison correction. No significant group differences were found in anterior temporal, frontal, insular, parietal, occipital, or subcortical regions. Contralateral hemispheric metabolism was preserved across all regions.

CONCLUSION: Consciousness impairment in right MTLE is specifically associated with posterior lateral temporal dysfunction, with broader posterior temporal vulnerability suggested by subthreshold trends. These findings identify posterior lateral temporal hypometabolism as a potential biomarker of impaired responsiveness in right MTLE and highlight the value of FDG-PET for characterizing consciousness-related network dysfunction.

PMID:41211287 | PMC:PMC12588851 | DOI:10.3389/fneur.2025.1690510