Functional compensation of the left dominant insula for language.

The left dominant insula was recently described as an essential area of speech, inducing definitive language disturbances when injured. We describe a patient with mild dysphasia, harboring a left insular glioma. A functional MRI found activations within the left inferior and middle frontal gyri, superior temporal gyrus, basal ganglia, but not in the insula. Surgery was performed using intraoperative electrical mapping in the awake patient, identifying the same language sites as showed by fMRI. A complete glioma resection was then performed. Despite an entire dominant insula removal, the patient presented no postoperative deficit, and even recovered from the preoperative dysphasia. This case illustrates the brain ability to maintain normal language without the left insula. The mechanisms of compensation are discussed.