Features of somatosensory manifestations induced by intracranial electrical stimulations of the human insula.

Objective: To study the clinical manifestations induced by intracranial electrical stimulation of the insular cortex in epileptic patients submitted to invasive stereo-electroencephalography (SEEG) recordings. Methods: We retrospectively studied the clinical manifestations induced by intracerebral electrical stimulations of the insular cortex in 96 patients. In order to precisely localize the position of the electrodes a postoperative 3D CT-scan or a 3D MRI was obtained and then the images were merged with the preoperative MRI in the same stereotactic referenced system. Results: A total of 341 electrical bipolar stimulations were performed. The most frequently induced symptom was a somatosensory manifestation (70%), mainly tingling and electric sensation involving the contralateral face and arm. Motor responses represented the 8% of the total amount, as well as auditory phenomena. Language dysfunction accounted for 2% of responses. Autonomic and gustatory phenomena represented respectively 1% of responses. Conclusion: we found a great prevalence of somatosensory manifestations whereas other types of clinical modifications were extremely infrequent. Significance: Our data support a prominent somatosensory role of the human insular cortex and provide a precise characterization of the different types of sensory manifestations induced by intracranial electrical stimulation of the human insula.