09-24 – Lexical retrieval delays in brain tumour patients: nouns and finite verbs in the past and present tense

Introduction: The glioma language profile encompasses a global decline of linguistic processing that may manifest as slowed reaction time (RT) on linguistic tasks which is often overlooked by error-based aphasia assessments. Moreover, evidence from frontal and temporal stroke suggests greater difficulties with processing verbs over nouns, particularly for past relative to present tense verbs. The current study aimed to examine whether these dissociations extend to RT and accuracy in glioma patients during object naming (ON) and action naming with finite verbs (ANFV).

Methods: Three patients undergoing awake craniotomy for the excision of low-grade gliomas (frontal, temporal and parietal) were recruited. Picture naming tasks (ON, past/present ANFV) were adapted for use as RT tasks. Patients were assessed pre- and post-operatively and performance was compared with healthy age/education matched controls.

Results: At three months postoperatively, all patients were impaired on at least 2/3 tasks in terms of RT but not accuracy, in relation to controls and/or baseline. In the frontal patient, RT was more impaired on ANFV compared to ON, while temporal and parietal patients showed no dissociation. Notably, in all cases, RT was more impaired for past compared to present tense ANFV. Although accuracy was not significantly impaired on any task, errors were only evident for ANFV. Slowed RTs did not correlate with standard aphasia assessment on which patients were clinically unimpaired.

Conclusions: RT tasks may offer higher sensitivity to capture retrieval impairments in glioma than error-based assessment. Greater difficulties for verb over noun retrieval in frontal glioma aligns with evidence from frontal stroke aphasia. Greater difficulties with reference to the past over present in glioma coincide with evidence from stroke. Perioperative assessment may benefit from the incorporation of reaction time measures, particularly tasks of complex grammatical production.