New concepts in surgery of WHO grade II gliomas: functional brain mapping, connectionism and plasticity - a review

Journal of Neuro-Oncology (2006) 79: 77115 Springer 2006

DOI 10.1007/s11060-005-9109-6Editors Invited Manuscripts-Invit. onlyNew concepts in surgery of WHO grade II gliomas: functional brain mapping,connectionism and plasticity a reviewHugues DuauDepartment of Neurosurgery UMR-S678 Inserm, Ho`re, Paris, FranceKey words: connectivity, electrical stimulation, functional brain mapping, low-grade glioma, plasticity, surgerypital SalpetrieSummaryDespite a recent literature supporting the impact of surgery on the natural history of low-grade glioma (LGG), the

indications of resection still remain a matter of debate, especially because of the frequent location of these tumors

within eloquent brain areas thus with a risk to induce a permanent postoperative decit. Therefore, since the

antagonist nature of this surgery is to perform the most extensive glioma removal possible, while preserving the

function and the quality of life, new concepts were recently applied to LGG resection in order to optimize

the benet/risk ratio of the surgery. First, due to the development of functional mapping methods, namely perioperative neurofunctional imaging and intrasurgical direct electrical stimulation, the study of cortical functional

organization is currently possible for each patient in addition to an extensive neuropsychological assessment. Such

knowledge is essential because of the inter-individual anatomo-functional variability, increased in tumors due to

cerebral plasticity phenomena. Thus, brain mapping enables to envision and perform a resection according to

individual functional boundaries. Second, since LGG invades not only cortical but also subcortical structures, and

shows an inltrative progression along the white matter tracts, new techniques of anatomical tracking and functional mapping of the subcortical white matter pathways were also used with the goal to study the individual

eective connectivity which needs imperatively to be preserved during the resection. Third, the better understanding of brain plasticity mechanisms, induced both by the slow-growing LGG and by the surgery itself, were

equally studied in each patient and applied to the surgical strategy by incorporating individual dynamic potential of

reorganization into the operative planning. The integration of these new concepts of individual functional mapping,

connectivity and plastic potential to the surgery of LGG has allowed an extent of surgical indications, an optimization of the quality of resection (neuro-oncological benet), and a minimization of the risk of sequelae (benet

on the quality of life). In addition, such a strategy has also fundamental applications, since it represents a new door

to the...