Language Mapping by Magnetoencephalography in Patients With Refractory Epilepsy: A Cohort Study

This study aimed to develop and validate magnetoencephalography paradigms for presurgical language mapping in patients with drug-resistant epilepsy.

This prospective observational study of 30 patients with drug-resistant epilepsy included two trials involving visual picture naming and auditory word recognition tasks. Language activation was analyzed using dynamic statistical parametric mapping for beta desynchronization and a fixed time window (350-500 ms). Concordance across trials, analysis methods, and functional MRI comparisons were also assessed.

Primary visual and auditory cortex activation occurred in 66.6 and 80% of the patients, respectively. Language-specific area activation was observed in 56.7% of the picture naming task patients and 70% of the auditory word recognition task patients. Lateralization was predominantly left sided in 41.1% (picture naming) and 61.9% (auditory word recognition) of cases, with some bihemispheric patterns. Beta desynchronization and fixed-time window analyses had comparable detection rates but with limited concordance. Magnetoencephalography-functional MRI lateralization agreement was 56.25% (Cohen kappa = 0.15). No significant correlations were found between the epilepsy parameters and language activation.

Magnetoencephalography provides valuable insights into language localization and functional reorganization in patients with epilepsy. Although task-specific activations highlight their utility, further studies with larger cohorts and gold-standard validations are needed to enhance their clinical applicability in presurgical planning.