Neurocognitive functioning in patients with glioma of the left and right temporal lobes

Patients with glioma frequently suffer from deficits of neurocognitive functioning (NCF), though few studies have assessed NCF in localized glioma patients prior to surgery. One hundred and three patients (M age = 52.0; M education = 14.6 years) with histologically confirmed glioma in the right (RTL: n = 30; 57 % glioblastoma) or left temporal lobe (LTL: n = 73; 49 % glioblastoma) completed presurgical neuropsychological assessment. Impairment of NCF was identified in 75 % of all patients. Notably, patients with RTL glioma were most frequently impaired on measures of verbal memory and executive functioning, and at similar rates as the LTL group. Nonetheless, χ(2) tests revealed that impairment rates were significantly higher in the LTL group on attention and object naming tests (p ≤ .05). Independent-samples t-tests revealed that mean performances of patients with LTL glioma were also significantly below RTL patients on measures of attention (p = .01), verbal learning and memory (p = .05), and language (p < .03). A trend was observed in which anterior LTL tumors were associated with reduced verbal learning and medial LTL lesions with delayed recall problems, though patients with lesions involving multiple LTL regions exhibited the greatest difficulty across all verbal memory measures. Significant group differences in NCF performances remained so after controlling for FLAIR volume and tumor histology. These findings indicate that temporal lobe glioma frequently present with impaired NCF, though impairments are often milder in RTL compared to LTL patients. Nonetheless, the relatively frequent verbal memory impairment in the RTL group underscores the bilaterality of verbal memory processes.