Language processing in glioma patients: speed or accuracy as a sensitive measure?

Abstract

ABSTRACT Background Glioma (brain tumour) patients can suffer from mild linguistic and non-linguistic cognitive problems when the glioma is localised in an eloquent brain area. Word-finding problems are among the most frequently reported complaints. However, mild problems are difficult to measure with standard language tests because they are generally designed for more severe aphasic patients. Aims The aim of the present study was to investigate whether word-finding problems reported by patients with a glioma can be objectified with a standard object naming test, and a linguistic processing speed test. In addition, we examined whether word-finding problems and linguistic processing speed are related to non-verbal cognitive abilities. Methods & Procedures We tested glioma patients (N=36) as part of their standard pre-treatment clinical work-up. Word-finding problems were identified by a clinical linguist during the anamnesis. Linguistic processing speed was assessed with a newly designed sentence judgment test (SJT) as part of the Diagnostic Instrument for Mild Aphasia (DIMA), lexical retrieval with the Boston Naming Test (BNT), presence of aphasia with a Token Test (TT), and non-verbal processing with the Trail Making Test A and B (TMT). Test performances of glioma patients were compared to those of healthy control participants (N=35). Outcomes & Results The results show that many glioma patients (58%) report word-finding problems; these complaints were in only half of the cases supported by deviant scores on the BNT. Moreover, the presence of reported word-finding problems did not correlate with the BNT scores. However, word-finding problems were significantly correlated with reaction times on the SJT and the TMT. Although there were no significant differences between the patient and control group on the SJT, a subgroup of patients with a glioma in the frontal lobe of the language-dominant hemisphere was slower on the SJT. Finally, performance on the SJT and TMT were significantly correlated in the patient group but not in the control group. Conclusions Linguistic processing speed appears to be an important factor in explaining reported word-finding problems. Moreover, the overlap between speed of language processing and non-verbal processing indicates that patients may rely on more domain-general cognitive abilities as compared to healthy participants. The variability observed between patients emphasises the need for tailored neuro-linguistic assessments including an extensive anamnesis regarding language problems in clinical work-up.