S43 Insular semiology: From observation of cases to cortical stimulation. Issue 9 (September 2017)

• Record Type: Journal Article
• Authors: Isnard, Jean
• Is Part Of: Clinical neurophysiology. Volume 128:Issue 9(2017:Sep.)
• Page Start: e193
• Publication Date: 2017-09
• Subjects: Insular epilepsy -- Functional anatomy -- Cortical stimulations; Neurophysiology -- Periodicals; Electroencephalography -- Periodicals; Electromyography -- Periodicals; Neurology -- Periodicals; 612.8
• DOI: 10.1016/j.clinph.2017.07.054
• Languages: English
• ISSNs: 1388-2457

Abstract

Abstract : Objectives: Stereotactic stimulations of the insular cortex through intracranial electrodes aim at characterizing the semiology of insular seizures. These stimulations, carried out in the context of Stereo-Electro-Encephalography (SEEG) during pre-surgical monitoring of epilepsy, reproduce the ictal symptoms observed during the development of insular seizures. Methods: We reviewed the results of insular stimulations performed in 222 patients admitted between 1997 and 2015 for pre-surgical SEEG exploration of atypical temporal or perisylvian epilepsy. Stimulations (50 Hz, trains of 5s, pulses of 0.5 ms, intensity 0.2–3.5 mA) were carried out using trans-opercular electrodes implanted orthogonal to mid-sagittal plane. Results: 550 of 669 stimulations were clinically eloquent in the absence of any post-discharge (237 and 313 respectively in right and left insula). Somatosensory responses (61% of evoked sensations) including pain and visceral sensations (14.9%) were the most frequent, followed by auditory sensations (8%), vestibular illusions (7.5%), speech impairment (5%), gustatory, (2.7%) and olfactory (1%) sensations. Although these responses showed some functional segregation (in particular a privileged pain representation in the postero-superior quadrant), there was a clear spatial overlap between representations of the different modalities. Discussion: Symptoms evoked by insular stimulations are multiple. None of them can be considered as absolutely specific to the insular cortex, but the occurrence in given seizure of a somatosensory symptom such as pain or of a laryngeal spasm associated to vestibular, auditory, aphasic, or olfacto-gustatory symptoms points to a discharge development in the insular cortex. Conclusion: Inular cortex is the only cortical region where stimulations demonstrate such a multi-modal representation.