Sentence comprehension deficits in aphasia : additional insights from impairment-specific assessment / Sandra Hanne

Sentence comprehension deficits in aphasia : additional insights from impairment-specific assessment / Sandra Hanne. In "Perspectives neuropsycholinguistiques sur l'aphasie - NeuroPsychoLinguistic Perspectives on Aphasia", colloque international organisé par l'Unité de Recherche Interdisciplinaire Octogone de l'Université Toulouse II-Le Mirail (France). Toulouse, 21-23 juin 2012.

Theoreticalbackground 
Despitegood performances in oral comprehension of single words andirreversible sentences, comprehension of semantically reversiblenon-canonical and complex sentences can cause enormous difficultiesin adults with aphasia (Mitchum & Berndt, 2008). As theseimpairments affect specific syntactic structures (Grodzinsky, 2000)and occur across various syndrome classifications (Dronkers et al.,2004), standardized aphasia batteries often fail to detect them.However, sentence comprehension deficits can have a considerableimpact on participation in everyday life (WHO, 2001). Following this,sensitive and in-depth tasks are required in order to tap theunderlying (syntactic) deficit, which is a prerequisite forimpairment-specific treatment.

Goal 
Theobjective is to present data from individuals with aphasiainvestigated with an in-depth assessment tool for sentencecomprehension using sentence-picture matching. The sentencecomprehension test (Burchert et al., 2011) systematically comprisessyntactic structures, which have been shown to be vulnerable tocomprehension impairments.

Method 
Wereport a case series study including 5 individuals with aphasia(38-74 years; 5-18 years post-onset), all native speakers of German,classified as Broca (n=3) and amnesic (n=2). Participants had aunilateral lesion in their dominant hemisphere, reduced memory spanand good performances in auditory discrimination and single-wordcomprehension. The sentence comprehension test included irreversiblesentences (long, short), reversible canonical (SVO, SRC) andnon-canonical sentence structures (OVS, ORC). SVO and OVS sentencescontained either number- or case-marking cues, whereas relativeclauses (SRC, ORC) were divided into right-branching and embeddedstructures. Thus, canonicityeffects,the influence of morpho-syntacticvariablesand syntacticcomplexity effectscan be investigated selectively.

Results 
Accordingto the standardized test battery (AAT, Huber et al., 1983) languagecomprehension seemed relatively intact (see percentiles in table 1).However, results of the sentence comprehension test showed severeimpairments as well as considerable heterogeneity in performances ofthe 5 participants (see table 1). Whereas all individuals performedwell on irreversible and reversible SVO sentences (above chance;within the normal range), accuracy dramatically declined for OVSstructures; reflecting a canonicityeffect.Comprehension of RCs was impaired in all 5 participants and a morespecific canonicity effect was observed for right-branching RCs for 2participants (P4, P5). Finally, these participants also showed asyntacticcomplexity effect,with decreased performance on embedded SRCs as compared toright-branching SRCs.

Conclusion 
Thepresent study indicates that adults with aphasia can have specificdeficits in oral sentence comprehension even though their syndromeclassification and percentiles in standardized aphasia batteries donot reveal any such severe impairment in comprehension. Furthermore,the results give insights into the selectivity of syntacticcomprehension deficits and their heterogeneous manifestations acrosssingle cases. This enunciates the clinical importance of sensitivetools assessing sentence comprehension in order to developevidence-based treatment programs.