Plasticity of cognitive functions before and after awake brain tumor surgery

Introduction: Deficits in cognition, i.e. language memory, attentional and executive functions are common in patients with primary brain tumors in eloquent areas (Papagno et al., 2011; Santini et al., 2012; Satoer et al., 2012). Tumor resection may aggravate these deficits, which can recover 1 year postoperatively (Satoer et al., 2014). This finding was based on group analyses, however in clinical practice individual variety is common. Pre- and postoperative neural plasticity mechanisms play an important role in brain tumor patients; substantial support is provided for a hodotopic (i.e. dynamic) approach of functional organization as opposed to a topological viewpoint (i.e. static) (Duffau, 2014). Aim: To describe the influence of plasticity on cognitive functions by means of pre- and postoperative profiles of patients with a similar brain tumor localization. Methods: We present 4 right-handed cases (P1, P2, P3, P4) originating from 2 outcome studies (De Witte et al., 2015; Satoer et al., 2014) with brain tumors in the same language areas (P1, P2: temporoparietal; P3, P4: insula) and operated awake. Language, memory, attentional and executive functions were formally examined pre- (all cases) and postoperatively (P3, P4: 3 and 12 months). Results: P1 and P2 showed opposite preoperative cognitive profiles. P1 obtained normal cognitive results and P2 had clinically significant impairments in all cognitive domains, (language, memory, attentional and executive deficits) (z-score ≥-1.50). P3 and P4 also demonstrate opposite preoperative profiles. P4 obtained intact cognitive results, whereas P3 was impaired in memory and executive functions (z-score ≥-1.50). Intraoperatively, in both P3 and P4 positive language sites were found (left inferior frontal gyrus and left parietal lobe). At 3 months postoperatively, P3 presented language deficits followed by recovery at 12 months, whereas P4 appeared to have recovered at 3 months postoperatively from the observed premorbid impairments in memory and executive functioning (z-score