Speaking without Broca's area after tumor resection

Abstract

We present the case of a right-handed patient who received surgical treatment for a left frontal WHO grade II glioma invading the left inferior and middle frontal gyri, the head of the caudate nucleus, the anterior limb of the internal capsule and the anterior insula, in direct contact also with the anterior-superior part of the lentiform nucleus. The tumor resection was guided by direct electrical stimulation on brain areas, while the patient was awake. Adding a narrative production task to the neuropsychological assessment, we compared pre-, peri- and post-surgical language skills in order to analyze the effects of the tumor infiltration and the consequences of the left IFG resection, an area known to be involved in various language and cognitive processes. We showed that the tumor infiltration and its resection did not lead to the severe impairments predicted by the localization models assigning a significant role in language processing to the left frontal lobe, notably Broca's area. We showed that slow tumor evolution – the patient had been symptom-free for a long time – enabled compensatory mechanisms to process most language functions endangered by the tumor infiltration. However, a subtle fragility was observed in two language devices, i.e., reported speech and relative clauses, related to minor working memory deficits. This case study of a patient speaking without Broca's area illustrates the efficiency of brain plasticity, and shows the necessity to broaden pre-, peri-, post-surgery language and cognitive assessments.