Effect of visual feedback on speech recovery and language plasticity in patients with post-stroke non-fluent aphasia. Functional MRI assessment
Résumé
Objective
To assess the efficiency of Visual Feedback (VF) on language recovery and plasticity in three chronic non-fluent aphasic patients. VF is based on language-action interaction, thus, language skills are improved by rehabilitation strategies based on execution and observation of motor actions. VF is an ultrasound system coupled with video images, allowing patients to ‘see their own lips and tongue at work’ during speech and improve their awareness of their lingual and labial movements and their ability to coordinate and combine phonemes and syllables. Brain plasticity was explored with functional MRI.
Material/Patients and methods
– Control group tested with functional MRI to identify language networks underlying three tasks of interest;
– three patients with non-fluent chronic aphasia after ischemic stroke, were examined in neuropsychology, speech therapy, acoustics and fMRI, before and after VF. VF has been applied during 14 sessions (2 weeks, 1 per day). The performance was evaluated before and after VF. In fMRI, specific comparisons were performed to identify:
– patterns of reorganization reflecting spontaneous neuro-plasticity,
– the effect of VF on speech recovery and language plasticity.
Results
After 14 sessions of VF, acoustic analyses showed a more canonical vowel production and better repetition of consonants. Speech analysis for repetition of syllables, naming and rhytme judgment, showed a general improvement of performances, variable among patients. In terms of cerebral activation, various patterns of language reorganization were obtained according to task and level of language recovery. A general trend can be identified with the improvement of language performance after VF, which is a right hemispheric predominance before VF, followed by a return of the activity to the left hemisphere, after VF.
Discussion - Conclusion
Results are discussed according to current models of inter and intra-hemispheric reorganization of language.