Perspectives on (A)symmetry of Arcuate Fasciculus. A Short Review About Anatomy, Tractography and TMS for Arcuate Fasciculus Reconstruction in Planning Surgery for Gliomas in Language Areas.

Andrea Di Cristofori,Ilaria Mauri,Martina Andrea Sirtori,Carlo Ferrarese,Carlo Giussani,Camilla De Laurentis,Gianpaolo Basso,Valeria Isella

doi:10.3389/fneur.2021.639822

Andrea Di Cristofori, Ilaria Mauri + Show 6 more

Open Access

https://doi.org/10.3389/fneur.2021.639822

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Abstract

Gliomas are brain tumors that are treated with surgical resection. Prognosis is influenced by the extent of resection and postoperative neurological status. As consequence, given the extreme interindividual and interhemispheric variability of subcortical white matter (WM) surgical planning requires to be patient's tailored. According to the “connectionist model,” there is a huge variability among both cortical areas and subcortical WM in all human beings, and it is known that brain is able to reorganize itself and to adapt to WM lesions. Brain magnetic resonance imaging diffusion tensor imaging (DTI) tractography allows visualization of WM bundles. Nowadays DTI tractography is widely available in the clinical setting for presurgical planning. Arcuate fasciculus (AF) is a long WM bundle that connects the Broca's and Wernicke's regions with a complex anatomical architecture and important role in language functions. Thus, its preservation is important for the postoperative outcome, and DTI tractography is usually performed for planning surgery within the language-dominant hemisphere. High variability among individuals and an asymmetrical pattern has been reported for this WM bundle. However, the functional relevance of AF in the contralateral non-dominant hemisphere in case of tumoral or surgical lesion of the language-dominant AF is unclear. This review focuses on AF anatomy with special attention to its asymmetry in both normal and pathological conditions and how it may be explored with preoperative tools for planning surgery on gliomas in language areas. Based on the findings available in literature, we finally speculate about the potential role of preoperative evaluation of the WM contralateral to the surgical site.

Highlights

Gliomas are intra-axial infiltrating brain tumors, boundaries of which within the perilesional white matter (WM) are very difficult to define [1, 2]
To our knowledge, very few studies explored the clinical relevance of these structural asymmetries for the functional outcome after brain surgery for gliomas. It is still unclear if subcortical variability could have a role in postoperative outcome and if it could be of some utility for the neurosurgeon to predict the risk of neurological deficits [9, 35]. In this mini-review, we focus on available evidence in the literature about one bundle considered of paramount importance for language functions, the arcuate fasciculus (AF), to better understand the meaning of its asymmetry for preoperative risk assessment of patients undergoing surgical resection for gliomas
Many studies show that Neuronavigated TMS (nTMS) has a good correlation with intraoperative findings obtained with direct cortical stimulation (DCS) [74, 75], a first experience published by Picht et al about correlation between DCS during awake craniotomy and presurgical nTMS showed a low positive predictive value of nTMS compared to DCS [76]

Summary

INTRODUCTION

Gliomas are intra-axial infiltrating brain tumors, boundaries of which within the perilesional white matter (WM) are very difficult to define [1, 2]. It is known that a brain lesion to the dominant hemisphere may induce a complex cortical functional reorganization of the language network that may involve a complex interplay of activity with contralateral homologous cortical areas and functional reorganization in the perilesional cortex, while it is still unclear how WM can functionally accommodate a brain damage induced by the tumor given its low neuroplastic potential [21, 22]. It is still unclear if subcortical variability could have a role in postoperative outcome and if it could be of some utility for the neurosurgeon to predict the risk of neurological deficits [9, 35] In this mini-review, we focus on available evidence in the literature about one bundle considered of paramount importance for language functions, the arcuate fasciculus (AF), to better understand the meaning of its asymmetry for preoperative risk assessment of patients undergoing surgical resection for gliomas

LANGUAGE WITHIN THE DOMINANT

AND RECOVERY FROM APHASIA

CONCLUSIONS

Findings

No of pts Results