Multimodality word-finding distinctions in cortical stimulation mapping.

Abstract

BACKGROUND: Cortical stimulation mapping (CSM) commonly uses visual naming to determine resection margins in the dominant hemisphere of patients with epilepsy. Visual naming alone may not identify all language sites in resection-prone areas, prompting additional tasks for comprehensive language mapping. OBJECTIVE: To demonstrate word-finding distinctions between visual, auditory, and reading modalities during CSM and the percentage of modality-specific language sites within dominant hemisphere subregions. METHODS: Twenty-eight patients with epilepsy underwent CSM by the use of visual, auditory, and sentence-completion tasks. Hierarchical logistic regression analyzed errors to identify language sites and provide modality-specific percentages within subregions. RESULTS: The percentage of sites classified as language sites based on auditory naming was twice as high in anterior temporal regions compared with visual naming, marginally higher in posterior temporal areas, and comparable in parietal regions. Sentence completion was comparable to visual and auditory naming in parietal regions and lower in most temporal areas. Of 470 sites tested with both visual and auditory naming, 95 sites were distinctly auditory, whereas 48 sites were distinctly visual. The remaining sites overlapped. CONCLUSION: Distinct cortical areas were found for distinct input modalities, with language sites in anterior tip regions found most often by using auditory naming. The vulnerability of anterior temporal tip regions to resection in this population and distinct sites for each modality suggest that a multimodality approach may be needed to spare crucial language sites, if sparing those sites can be shown to significantly reduce the rate of postoperative language deficits without sacrificing seizure control.