gms | German Medical Science

Objective: We herein present a series of 28 patients in whom we extended the surgical approach into eloquent brain areas with the help of image-guided functional surgery. We examined pre-and postoperative neurological deficits and prerequisites that allow for neurosurgery beyond the generally accepted limits.

Methods: Preoperative functional imaging with MEG and/or fMRI was performed. MEG measurements were carried out with a 2x37 channel biomagnetic system (Magnes II, 4-D Neuroimaging). Functional localization was performed with the 1-dipole fit or beamformer algorithm. For fMRI we used a 1.5T MR scanner with echo planar imaging (Sonata, Siemens Medical Solutions) and a block paradigm with 180 measurements in 6 blocks (rest alternating with activation, 25 slices, 3 mm thickness & resolution TR=2470, TE=60). DTI was used with 1.9 mm slices and 6 directions to reconstruct fiber connections within language areas or the pyramidal tract. Language tests were conducted pre- and postoperatively to show the recovery of neurological function. Intraoperative MRI was acquired and registered with the functional images to show the extent of resection and its relation to functional structures.

Results: Out of 287 patients with language mapping, there were 14 patients with surgery very close (< 1 mm) to language areas or fiber tracts and four patients even had surgery within structures connected to language functions. Among these were resections within the operculum of the inferior frontal gyrus (Broca’s area) or in the posterior supratemporal gyrus of the dominant hemisphere (Wernicke’s area). In 14 of the 383 patients with mapping of sensory and/or motor functions resection was very close (< 1mm) to the motor cortex or pyramidal tract and in 5 into the precentral gyrus (three cases in the area of the leg, one case in the area of the foot and one case in the area of the mouth). Transitory neurological malfunctions occurred; however, none of these patients had permanent worsening of their neurological abilities.

Conclusions: It is possible to avoid worsening of neurological deficits or even to achieve a slight improvement of the neurological status (paralysis or aphasia) if precise language- and motor mapping is used in conjunction with functional neuronavigation even when operating into eloquent brain areas.