Iterative Surgical Resections of Diffuse Glioma With Awake Mapping: How to Deal With Cortical Plasticity and Connectomal Constraints?

BACKGROUND In diffuse glioma, a multistage approach with iterative tailored surgical resections can be considered. OBJECTIVE To compare results of iterative intrasurgical brain mappings to investigate the potential and limitation of neuroplasticity at the individual stage, and to highlight to what extent it can influence the therapeutic strategy. METHODS Glioma patients who underwent 2 consecutive awake surgeries with cortical and subcortical stimulation were classified into group 1 (n=23) if cortical mappings exhibited high level of plasticity (displacement of >= 2 sites) or into group 2 (n=19) with low level of plasticity. RESULTS Clinical characteristics did not differ significantly between both groups. The borders of the tumors were mostly sharp in group 1 (82.6%) and rather indistinct in group 2 (84.2%), (P=.00001). Tumor remnants were more often cortical (subcortical) in group 1 (39.1%) and more often purely subcortical in group 2 (68.4%; P=.009). In group 1, the time needed to recover independence was significantly shorter at reoperation (37.6 h vs 78.3 h after the first surgery, P=.00003) while this difference was not significant in group 2. The iterative extents of resection (EOR) remain comparable in group 1 (94% vs 92%, P=.40) but were significantly smaller in group 2 at reoperation (94% vs 88%, P=.05). CONCLUSION More efficient plasticity mechanisms are facilitated by cortical tumors with sharp borders, are associated with an increase of EOR at reoperation and with earlier functional recovery. Tumoral invasion of the white matter tracts represents the main limitation of neuroplasticity: this connectomal constraint limits EOR during second surgery.