Speech rehabilitation in chronic post-stroke aphasia using visual illustration of speech articulators.A case report study

Question: Studies on the remediation of speech disorders suggest that providing visual information on speech articulators may contribute to improve speech production abilities. We evaluated the effect of a new rehabilitation method based on the display of pre-recorded articulatory movements, on the speech recovery of a patient with post-stroke non-fluent chronic aphasia. We propose that visualizing speech articulators, such as the tongue and lips, can increase the patient’s ability to recover speech motor programs and can improve their speech abilities. Methods: The rehabilitation was based on the Ultraspeech-player software which presents speech sounds together with the movements of the speech articulators (tongue and lips) of a reference speaker, recorded using ultrasound and video imaging. The patient was trained for 4 weeks (3 sessions/week) by watching and hearing target phonemes and syllables and by imitating them. The effects of this method were assessed by analyzing, before and after rehabilitation: (i) the accuracy scores during four speech tasks (phoneme and word repetitions, word reading and phonemic discrimination); (ii) the phonological processes identified in the errors made during the phoneme repetition task and (iii) the acoustic parameters (voice onset time VOT, formants F1 and F2, spectral moments) obtained from the audio signal recorded in the phoneme repetition task. A neuropsychological assessment was also performed, before and after rehabilitation, in order to evaluate: cognitive performances, executive function, visual episodic memory, mental rotation abilities and mood. Results: Our results showed that the illustration-based rehabilitation method had a beneficial effect on the patient’s speech production and reading abilities. The positive impact was stronger for stop and fricative consonants, which are targeted by the software (higher visibility of the articulatory configurations). Acoustic parameters reveal an improvement in the VOT for stop consonants and in the place of articulation for fricatives (alveolar, post-alveolar and labiodental). However, the patient showed little improvement for vowels. Moreover, the integrity of visuo-spatial ability, short-term and working memory and some executive functions also supports the effectiveness of the rehabilitation method. Conclusion: These findings support the use of an illustration-based rehabilitation method and argue for the necessity of detailed qualitative and quantitative assessment in speech production to provide more thorough descriptions of speech abilities in patients with non-fluent aphasia.