NCOG-49. Neurocognitive outcomes after resection of left inferior parietal lobule gliomas

Risk of postoperative decline in neurocognitive function (NCF) varies by regional tumor involvement. Little work describes NCF changes specifically related to resection of dominant inferior parietal lobe tumors, despite known associations with higher-order linguistic functions. Retrospective review identified patients (Age M(SD)=53.69(16.88)) with newly diagnosed left inferior parietal lobe glioma (78.1% high grade) that completed neuropsychological testing preoperatively (N=32) and within 2 months postoperatively (N=22). Tumors were characterized as involving supramarginal gyrus (SMG: 43.8%), angular gyrus (AG: 21.9%), or both (34.4%). At baseline, median KPS was 90 (range: 80-100), though cognitive impairment (demographically-adjusted z-score≤-1.5) was common (87.5% on ≥1 test) and most frequent in verbal fluency (COWA: 58.1%), executive functioning (TMTB: 48.3%), verbal learning (HVLT-R TR: 46.7%) and memory retrieval (HVLT-R DR: 57.7%). Postoperative neurocognitive decline (≥1 SD worsening) was also common (69.6% on ≥1 test) and most frequent and severe in the same domains. There was no association between NCF z-score change and localization specific to SMG or AG, though confrontation naming decline appeared greatest when tumors involved both regions (p=0.016). Larger preoperative tumor volume was associated with greater improvement postoperatively in attention (Digit Span; r=0.56, p=0.007), verbal learning (HVLT-R TR: r=0.45, p=0.042), processing speed (Coding: r=0.56, p=0.007), and verbal fluency (COWA: r=0.56, p=0.006). However, in multivariable regression, interaction between volume and EOR was a better predictor of attention, processing speed, and fluency than either alone, accounting for 29-32% of variance. Neurocognitive impairment preoperatively and neurocognitive decline in the relatively early term following resection of dominant inferior parietal lobe glioma is common. Patterns of NCF change resemble that seen in other patients with perisylvian region tumors, though findings suggest lesions involving both SMG and AG may confer increased risk to naming. Postoperative outcomes are more favorable in patients with larger tumors who achieve greater EOR.