P 67 Electrophysiological correlates of language improvements after intensive language therapy in patients with chronic post-stroke aphasia

Abstract

Background Aphasia affects approximately one third of all stroke patients and may lead to chronic disability. Effective neurorehabilitation programs focusing on improving speech and language in patients with post-stroke aphasia are essential. A better understanding of the neurobiological processes accompanying language deficits and rehabilitation may bear fruit in the advancement of neurorehabilitation programs. Methods Clinical language performance and neurophysiological correlates of language processing were measured before and after intensive language therapy in patients with chronic (time post-stroke > 1 year) post-stroke aphasia. The mismatch negativity (MMN), a language-related event-related potential (ERP) known to reflect automatic lexico-semantic and grammar processing, was recorded in a distracted oddball paradigm to short spoken sentences. Critical “deviant” sentence stimuli where either well-formed and meaningful, or grammatically incorrect, or meaningless. Results The Aachen Aphasia Test (AAT) demonstrated significant clinical language improvements, which were accompanied by enhancement of the MMN responses, after 4 weeks of speech-language therapy (SLT) delivered with high intensity (10.5 h per week). In particular, MMN amplitudes to grammatically correct and meaningful sentences and to sentences containing a meaningless pseudoword significantly increased after therapy. However, no therapy-related changes in MMN were found for grammatically incorrect sentences that violated pronoun-verb agreement. Discussion/conclusions MMN increases to well-formed meaningful and to meaningless strings and the absence thereof for ungrammatical sentences suggest neuroplastic changes consistent with recent cognitive linguistic theories. The results confirm previous reports that intensive SLT leads to improvements of language and communication skills in chronic aphasia patients and now demonstrate that this clinical improvement is associated with enhanced automatic brain indexes of language processing above single-word level. Furthermore, the data suggest that the language-elicited MMN may be a useful tool to map functional language recovery in post-stroke aphasia patients.