The Association Between Task Complexity and Cortical Language Mapping Accuracy.

Background And Objectives: Direct cortical stimulation (DCS) mapping enables the identification of functional language regions within and around gliomas before tumor resection. Intraoperative mapping is required because glioma-infiltrated cortex engages in synchronous activity during task performance in a manner similar to normal-appearing cortex but has decreased ability to encode information for complex tasks. It is unknown whether task complexity influenced DCS mapping results. We aim to understand correlations between audiovisual picture naming (PN) task complexity and DCS error rate. We also asked what functional and oncological factors might be associated with higher rates of erroneous responses.

Methods: We retrospectively reviewed intraoperative PN and word reading (WR) task performance during awake DCS language mapping for resection of dominant hemisphere World Health Organization grade 2 to 4 gliomas. The complexity of word tested in PN/WR tasks, patient characteristics, and tumor characteristics were compared between correct and incorrect trials.

Results: Between 2017 and 2021, 74 patients met inclusion criteria. At median 18.6 months of follow-up, 73.0% were alive and 52.7% remained recurrence-free. A total of 2643 PN and 978 WR trials were analyzed. A greater number of syllables in PN was associated with a higher DCS error rate ( P = .001). Multivariate logistic regression found that each additional syllable in PN tasks independently increased odds of error by 2.40 ( P < .001). Older age was also an independent correlate of higher error rate ( P < .043). World Health Organization grade did not correlate with error rate ( P = .866). More severe language impairment before surgery correlated with worse performance on more complex intraoperative tasks ( P < .001). A higher error rate on PN testing did not correlate with lower extent of glioma resection ( P = .949).

Conclusion: Word complexity, quantified by the number of syllables, is associated with higher error rates for intraoperative PN tasks but does not affect extent of resection.