White matter functional connectivity as an additional landmark for dominant temporal lobectomy

Dominant temporal lobectomy is classically performed based on two criteria: a perfect knowledge of the temporo-mesial microsurgical anatomy and cortical landmarks laterally. However, the functional anatomy of the subcortical white matter tracts is taken into account less, despite the risk of inducing a permanent deficit (especially aphasia) if damaged. Even if Klinger's technique allows dissection of fibres on cadaveric specimens, the exact three dimensional geometry of these fasciculi remains poorly described. Tractography, based on diffusion tensor imaging (DTI), is a powerful tool to build three dimensional images of several fasciculi, helping neurosurgeons to create a mental representation of their relationships. Moreover, intraoperative subcortical electrostimulation enables mapping of the function of these pathways. Here we review the recent findings on the white matter anatomo-functional connectivity of the dominant temporal lobe, based on combined anatomical data provided by DTI and functional information provided by intraoperative stimulation. We then discuss their implications for temporal lobectomy, by using white matter functional connectivity as an additional landmark.