Preferential brain locations of low‐grade gliomas

BACKGROUND: The objectives of this study were to register the brain locations in a consecutive series of low-grade gliomas (LGGs) and compare these localizations with the locations of de novo glioblastomas (GBMs) that were collected during the same period in an effort to analyze whether LGGs are situated in preferential areas and to review the pathophysiologic hypothesis of such a phenomenon. METHODS: One hundred thirty-two patients with LGG and 102 patients with GBM who were followed consecutively between 1996 and 2003 by the authors were reviewed, whatever their treatment. Using anatomic, three-dimensional magnetic resonance imaging, the location of each tumor was analyzed accurately according to a classification system based on the proximity of eloquent areas previously reported by the authors. RESULTS: One hundred nine LGGs (82.6%), compared with 55 GBMs (53.9%), were situated within functional regions (P < 0.001). More specifically, 36 LGGs (27.3%), compared with 11 GBMs (10.8%), were localized in the region of the supplementary motor area (SMA) (P < 0.001); and 33 LGGs (25%), compared with 11 GBMs (10.8%), were located within the insula (P < 0.001). CONCLUSIONS: The current findings suggest that LGGs are located preferentially in "secondary" functional areas (immediately near the so-called primary eloquent regions), especially within the SMA and the insular lobe. This preferential localization may be explained by developmental, cytomyeloarchitectonic, neurochemical, metabolic, and functional reasons. A better knowledge of the pathophysiologic mechanisms underlying preferential LGGs locations may improve understanding of the genesis and natural history of these tumors and, subsequently, their management.