Phonological rehabilitation in acquired aphasia

Introduction The phonological deficits affecting the output performance of patients with acquired language impairment (a disorder that is often classified under the label of conduction aphasia of the reproduction type) usually arise at the phonological selection and sequencing levels (i.e. impaired pathway from lexical phonological codes to phonological output buffer or direct damage to the output buffer itself). Different approaches were employed to treat acquired phonological assembly difficulties in aphasia, and their effectiveness has been challenged (see for a review Corsten et al., 2007; Franklin, Buerk, & Howard, 2002; Waldron, Whitworth & Howard, 2011). In the present study, we describe, and test for effectiveness, a phonological cognitive-linguistic training procedure aimed to tackle the patients’ ability to discriminate phonological input information, and to reconstruct, reinforce and reautomatize the ability to generate target phonological strings. Materials and Methods Participants. The treatment effectiveness has been tested on three chronic aphasic patients (eight or more months after aphasia onset) with severe phonological monitoring deficits. PA is a 50-year-old schoolkeeper. Eighteen months before admittance to the study she suffered a left temporo-parietal hematoma. Her language impairment was fluent with predominant phonemic paraphasia. She also suffered a moderate phonemic discrimination deficit (mild-to moderate verbal deafness). LA is a 61-year-old, company manager. Fourteen months before entering the study he suffered a left fronto-opercular, insular and lenticular stroke. His language impairment was mixed, with poor speech output, severe phonemic paraphasia and apraxia of speech. AZ is a 60-year-old concierge. Eight months before study onset he suffered a left temporo-parietal stroke. His language impairment was fluent with predominant phonemic paraphasia. Training procedure. The treatment program is based on a minimal pair and contrastive drill procedure, which prompts phonological contrasts at input (when required) and output level, by means of a repetitive and pressing pace (phonological drill). The procedure aims at stabilizing the treated phonological sequences and at determining progressive shift to a voluntary control of phonological sequencing. The training is organized in six stages, and is based on a list of 77 Italian syllables and, afterwards, on several lists of words with increasing phonological complexity (continuant vs. plosive consonants), syllable length (two, three and four syllables), and consonant cluster complexity (consonant-vowel alternation, two- and three-consonant clusters). The rehabilitation program was carried out individually, three times per week, 45 minutes per session, for a total of 40 training sessions. Treatment effectiveness. The patients’ phonological abilities were tested before and after treatment. Different but parallel word lists were employed (reading aloud, repetition, written spelling) to test the effectiveness of the treatment on the training material, and the generalization of the improvement to non-trained material (same sounds but combined in different words, which were matched for length and word frequency with those employed in the treatment). Generalization to a different production context was also tested using a picture-naming task of nouns and verbs. Finally, a three-month follow-up evaluation allowed to test for stability of the treatment effects. Results The 40-session limit did not allow any of the patients to complete the entire treatment protocol. Both for patients PA and AZ the improvement observed for the treated material also generalized to non-treated material (but with identical phonological characteristics and matched word frequency): PA improved significantly his reading aloud, but less extensively on tasks requiring phonological input analysis (repetition, spelling from dictation), probably due to some residual verbal deafness; AZ obtained a major improvement on all tasks. PA’s and AZ’s recovery remained stable after a three-month follow-up. The phonological improvement also generalized to a picture-naming task both in patients LA and AZ, but only for the latter such generalization remained stable at three-month follow-up. Discussion This study tested the effectiveness of a cognitively sound phonological treatment in three aphasic patients with predominant phonological deficit (that usually arise at the phonological selection and sequencing levels). The aim of the treatment is to reconstruct, reinforce and automatize the patients’ ability to process complex phonological strings. Results demonstrate that the treatment procedure is a successful technique and that its effect generalizes to non-treated material. Indeed, in two of the three patients the phonological performance improved significantly on the syllable list as well as on both the treated and non-treated word lists, and the recovery maintained over a three-month follow-up. The phonological improvement generalized also to the performance on a picture-naming task. However, the training did not appear to be successful in the patient in which the phonological deficit was associated to speech apraxia. In conclusion, an impairment-specific and material-based therapy approach is promising for the treatment of impaired sublexical phonological processing. References Franklin, S., Buerk, F. & Howard, D. (2002) Generalised improvement in speech production for a subject with reproduction conduction aphasia. Aphasiology, 16, 1087-1114. Waldron, H., Whitworth, A. & Howard, D. (2011). Comparing monitoring and production based approaches to the treatment of phonological assembly difficulties in aphasia. Aphasiology, 25, 1153-1173. Corsten, S., Mende, M., Cholewa, J. & Huber, W. (2007). Treatment of input and output phonology in aphasia: A single case study. Aphasiology, 21, 587-603.