Contralateral insular involvement producing false lateralizing signs in bitemporal epilepsy: A stereo-encephalography case report

Although rare, epilepsy arising from the insula may produce ictal manifestations that can mimic temporal and extratemporal semiologies. If unrecognized, this might lead to some epilepsy surgery failures. Seizures originating in the insula (insular epilepsy) produce semiologies such as sensation of laryngeal/ chest discomfort, contralateral widespread unpleasant somatosensory auras, oro-alimentary movements, and dysphonic/dysarthric speech, which usually occur with fully preserved awareness. Insular involvement after ictal propagation of seizures arising from temporal or frontal areas may produce a similar semiology, or limited to the objective features as subjective sensations are often masked by dysfunction of consciousness and memory. Propagation of epileptic activity between mesial temporal structures and the ipsilateral insula is remarkably rapid, reflecting the dense connections between the insula and temporolimbic structures. Spread from the mesial temporal structures to the contralateral insula has beenmentioned in a study on technical details of insular implantation in SEEG. Here, we report a patient with ultimately bitemporal epilepsy. Using stereo-EEG, spread of ictal activity from the left mesial temporal region into the right insula and primary motor face area was demonstrated that resulted in mislateralizing semiological signs (vomiting and left face clonic movements).