Systematic Review of Functional Mapping and Cortical Reorganization in the Setting of Arteriovenous Malformations, Redefining Anatomical Eloquence

Abstract

The goal of this study was to systematically review functional mapping and reorganization that takes place in the setting of arteriovenous malformations (AVMs) and its potential impact on grading and surgical decision making. Methods: A systematic literature review was performed using the PubMed database for studies published between 1986 and 2019. Studies assessing brain mapping and functional reorganization in AVMs were included. Results: Of the total 84 articles identified in the original literature search, 12 studies were ultimately selected. This includes studies evaluating the impact of cortical reorganization on patient outcomes and factors impacting and triggering cortical reorganization in AVM. Conclusion: These studies demonstrate the utility of preoperative brain mapping and acknowledgment of functional reorganization in the setting of AVMs. While these findings led to alterations in Spetzler-Martin grading and subsequent surgical decision making, it remains unclear the clinical utility of this information when assessing patient outcomes. While promising, more research is required before recommendations can be made regarding functional brain mapping and cortical reorganization with respect to AVM surgery involving eloquent brain tissue.

Most Promising Approaches to Improve Brain AVM Management: ARISE I Consensus Recommendations

“…29 However, it is important to note that fMRI may be susceptible to distortions due to bAVM-induced hemodynamic changes, potentially leading to misinterpretations, especially in cases of high flow artifacts. 32 In contrast, navigated transcranial magnetic stimulation produces a potent magnetic field to either stimulate or inhibit underlying brain tissue, offering a reliable method for generating evoked potentials and mapping sensory and motor cortex regions. 33 Importantly, navigated transcranial magnetic stimulation is not affected by bAVM-induced hemodynamic variations, making it a more dependable choice than fMRI when assessing the presence of eloquent areas in proximity to bAVMs.…”

Impacting the Treatment of Highly Eloquent Supratentorial Cerebral Cavernous Malformations by Noninvasive Functional Mapping—An Observational Cohort Study

“…20 Navigated transcranial magnetic stimulation (nTMS) has already shown beneficial for the rating of eloquence during the decision-making for or against surgical treatment of brain arteriovenous malformations (BAVMs). [21][22][23][24] Used standardly for pre-and intraoperative planning during resection of eloquently located brain tumors, [25][26][27][28][29][30][31] this neurophysiological technique is qualified for pre-and intraoperative risk assessment due to its ability to objectively measure functional eloquence of surrounding brain tissue. [32][33][34] Additionally, nTMS-based tractography can visualize eloquent white matter pathways of the motor and language network with high accuracy by visualizing subcortical fibers originating from cortical areas of known function.…”