Abstract
BACKGROUND
Low-grade glioma (LGG) patients typically suffer from mild aphasia that often cannot be detected with standard aphasia tests. The Diagnostic Instrument for Mild Aphasia (DIMA) is the first standardized test-battery to assess mild language disorders. We investigate pre- and postoperative linguistic abilities of LGG and high-grade glioma (HGG) patients with the DIMA.
METHODS
The DIMA consists of subtests that tap phonology (word, compound, non-word, sentence repetition), semantics (odd-picture-out), and syntax (sentence completion). Additionally, we administered the Boston Naming Test, Category- and Letter Fluency, and the Token Test. Patients were assessed before awake surgery (T1, N=98), three-months (T2, N=69), and one-year (T3, N=30) postoperatively. DIMA performance was compared to healthy controls (N=214). Group differences were examined with parametric (t-test) and nonparametric (Mann-Whitney-U, Wilcoxon) tests.
RESULTS
DIMA: Preoperatively, patients deviated on sentence repetition and sentence completion (p<0.05). HGG patients performed worse than LGG on word, non-word, and sentence repetition (p<0.05). There was no effect of hemispheric tumor localization. At T2, compound repetition and odd-picture-out also became impaired (p<0.05) and there was a decline compared to T1 on all repetition tasks (p<0.05). At T3, only sentence completion remained impaired (p<0.01) with a deterioration compared to T1 (p<0.01).
Standard tests: At T1, patients were impaired on BNT, Category- and Letter Fluency (p<0.01). HGG patients performed worse than LGG patients on BNT and TT (p<0.01). Patients with left-hemispheric tumors performed worse on BNT and Letter Fluency compared to right-hemispheric tumors (p<0.05). At T2, TT also became impaired (p<0.05) and patients declined compared to T1 on Verbal Fluency tests (p<0.01). At T3, only BNT and Category Fluency remained impaired (p<0.05), with no significant declines compared to T1.
CONCLUSION
The DIMA is the first test-battery to detect peri-operative impairments at different linguistic levels (phonology, semantics, syntax) in patients with left- or right-hemispheric gliomas. It even appeared more sensitive to detect surgical effects than standard tests: all phonological DIMA subtests captured short-term decline (T1-T2), in line with earlier evidence for the value of (non-)word repetition. DIMA sentence completion detected long-term decline (T1-T3), reflecting earlier spontaneous speech analyses. As expected, Verbal Fluency was also sensitive to short-term postoperative decline. Left-hemispheric tumor localization only affected standard test performance. HGG patients had more severe impairments than LGG on DIMA repetition and standard tests (BNT and TT). We advise adding the DIMA to standard language evaluation of glioma patients, as it allows for more detailed counseling about language outcome.
