Atypical language cortex in the left temporal lobe: relationship to bilateral language

Abstract

Background: The intracarotid amobarbital procedure (IAP) is widely used in the preoperative evaluation for epilepsy surgery to lateralize language dominance and memory functions. However, language mapping has most often been accomplished with cortical brain stimulation.

Objective: To examine left temporal lobe language cortex representation using this technique in patients with bilateral language (BL) as compared with patients with left language dominance (LD).

Methods: The language maps of each patient were reviewed retrospectively. Group I consisted of 10 patients with BL and Group II consisted of 10 matched control patients with LD. Each stimulation trial included a brief assessment of confrontation naming, automatic speech, reading, repetition, and comprehension. Clusters of errors that included comprehension, repetition, and naming defined primary temporal lobe language areas.

Results: Mapping revealed two distinct language areas in 60% of patients in Group I and 10% in Group II (p = 0.019). In Group I, two patients had both language areas in the same gyrus (either the superior or the middle temporal gyrus), whereas two showed one language area each in the superior and middle temporal gyri and the remaining two had one in the superior temporal gyrus and the other intermixed between the superior and middle temporal gyri. In Group II, both language areas were intermixed between the superior and middle temporal gyri.

Conclusions: Bilateral language (BL) representation in the intracarotid amobarbital procedure is frequently associated with more than one noncontiguous language area in the left temporal lobe. A careful search for multiple language areas, particularly in patients with BL, is prudent prior to surgical resection.