Thomas P. Marquardt

Developmental apraxia of speech : determiners of differential diagnosis

Developmental apraxia of speech (DAS) is a neurologically based disorder in the programming of sequential articulatory movements. This definition, based purely on motoric limitations, is fraught with controversy concerning aetiology, clinical manifestations, treatment, and even identification of the disorder as a separate clinical entity. An understanding of developmental apraxia depends on consistent utilization of a group of symptoms for diagnosis so that data-based results can be used to generate inferences about the disorder. Results from studies of children who are diagnosed with developmental apraxia, but who may not be apraxic, complicates application to theories attempting to account for observed symptoms. A longitudinal study of children with DAS has been under way at the University of Texas at Austin since 1985. Of 22 children referred as apraxic, a diagnosis has been confirmed in only four. Phonological and language evaluation data for five clients evaluated during this project are presented. O...

The perception and production of rhyme in normal and developmentally apraxic children

The phonological competence of four children, aged 5-7 years old, who demonstrated a cluster of symptoms consistent with a diagnosis of developmental apraxia of speech (DAS), was contrasted to that of four normal children. Four rhyming tasks were used to assess the ability of the children to both spontaneously generate rhyming words to targets and to judge the (in)appropriateness of a rhyme in both a word series and forced-choice word pairs. The DAS children revealed a severe deficit in rhyming ability across all tasks and had rhyming abilities markedly inferior to those shown by normal children. The rhyming results were interpreted as possibly indicative of an impoverishment of an internalized phonemic representation system, which precludes accessing and evoking the needed sound image for the vowel + coda for a rhyme. These results, while preliminary in nature, lend support to a conceptualization of DAS as a fundamental disorder of the segmental phonological level of language that impacts on all hierarchically relevant language components. The hypothesis that the underlying etiology of DAS is a developmental dysmorphology of the neural substrates that mediate such basic phonological representational structure is discussed.

A Comparison of the Codeswitching Patterns of Aphasic and Neurologically Normal Bilingual Speakers of English and Spanish

Conversational discourse samples were obtained from four aphasic and four neurologically normal Hispanic bilinguals in monolingual English, monolingual Spanish, and bilingual contexts to identify codeswitching patterns. Analysis of the samples based on the Matrix Language Frame (MLF) Model (Myers-Scotton, 1993a) revealed consistent matching of the language context by the aphasic and normal subjects. The aphasic subjects demonstrated a greater frequency of MLF constituents and codeswitching patterns not evident in the speech samples of the normal subjects. Results suggest an increased dependence on both languages for communication following neurological impairment.

Token‐to‐token variability in developmental apraxia of speech: three longitudinal case studies

Variability in the speech production patterns of children with developmental apraxia of speech (DAS) was investigated in a three‐year longitudinal study of three children with DAS. A metric was developed to measure token‐to‐token variability in repeated word productions from connected speech samples. Results suggest that high levels of total token and error token variability and low levels of word target stability and token accuracy characterize the disorder. Overall levels of variability and patterns of change over time differed between participants. Longitudinal patterns were indicative of decreasing total token variability and increasing token accuracy. However, change was not consistently unidirectional for two of the three children in the study, suggesting day‐to‐day performance differences in addition to within‐session variability.

Picture naming and identification in bilingual speakers of Spanish and English with and without aphasia

Background: Equivalent language knowledge is assumed in interpreting assessment results from bilingual speakers with aphasia, regardless of pre‐morbid language experience. Aims: The purpose of this study was to investigate the affect of pre‐morbid language skill, estimated from the performance of 20 neurologically normal bilinguals, on picture identification and naming in four bilingual speakers of Spanish and English with aphasia. Methods & Procedures: Statistical and qualitative analyses of proficiency, language use patterns, literacy, and concentrated language experience were investigated in relation to between‐language differences in picture identification and naming. Outcomes & Results: Three patterns of impairment were identified: higher scores in English consistent with pre‐morbid skill, higher scores in Spanish inconsistent with pre‐morbid skill, and variable performance inconsistent with pre‐morbid skill. Conclusions: Results suggest that interpretation of language impairment in adult bilingual speakers within a given bilingual community must consider expected variability in the proficiency and use of the languages spoken and the differential effects of proficiency on expressive and receptive language performance.

Comprehension and expression of affective sentences in traumatic brain injury

The comprehension and production of affective prosody and facial expression was investigated in subjects with traumatic brain injury and matched normal subjects. Performance on tasks designed to assess the ability to recognise affect in congruous, neutral, and ambiguous sentences and the ability to portray emotions in affectively neutral sentences revealed significant impairments for the subjects with traumatic brain injury. Analysis of correct responses to ambiguous sentences found increased reliance of brain-injured subjects on verbal compared to paralinguistic cues in interpreting the emotion of the sentence. The clinical implications of the findings relative to counselling, compensation strategies, and direct intervention for patients with traumatic brain injury are discussed.

Vowel patterns in developmental apraxia of speech: three longitudinal case studies

Vowel inventories and error patterns for three children with suspected developmental apraxia of speech (DAS) were analysed over a 3‐year period using phonetic transcriptions of connected speech samples. The children demonstrated complete English vowel inventories except for rhotics. However, accuracy of vowel targets in connected speech did not normalize during this period. No consistent patterns of vowel errors were found. There was no decrease in vowel accuracy with increased utterance length or syllable complexity. Findings indicate persistence of vowel inaccuracy in the presence of a relatively complete vowel inventory. This longitudinal data can help to build consensus on use of vowels as a potential clinical marker for differential diagnosis of DAS.

The performance of neurologically normal bilingual speakers of Spanish and English on the short version of the Bilingual Aphasia Test

Background: The assessment of aphasia in bilingual speakers is complicated by the need to measure language impairment in each language, as well as defining how one language recovers in relation to another. The Bilingual Aphasia Test (BAT) is a criterion‐referenced measure designed to provide the requisite data needed to measure the impairment of bilingual speakers with aphasia while minimising the effects of pre‐morbid differences in language skill. Aims: The purpose of this study was to examine the performance of neurologically normal adult bilingual speakers on the short version of the BAT (English and American Spanish). Methods & Procedures: A total of 22 adults ranging in age from 51 to 77 completed the BAT as well as a series of measures of language history, proficiency, and use. Outcomes & Results: Results indicated that the group scored higher in English than in Spanish on the BAT. BAT performance was consistent with higher proficiency in English than Spanish, as indicated by responses to language background measures. An item analysis identified 54 items with a correct response rate less than 70%; the majority of these items were from the Spanish version and the translation subtest of the BAT. Conclusions: Performance on the Spanish BAT was influenced by academic experience in Spanish, and the influence of English on Spanish. Interpretation of BAT results for bilingual speakers with aphasia requires accounting for pre‐morbid differences in language skill.

Affective processing in left and right hemisphere brain-damaged subjects with and without subcortical involvement

Affective processing ability was examined in right and left hemisphere brain-damaged subjects with cortical lesions that were grouped according to the presence or absence of concomitant subcortical basal ganglia damage. The ability to process affective speech prosody, emotional facial expressions, and linguistically coded emotional messages was measured in isolated identification tasks. Results indicated that subjects with damage to subcortical structures in addition to cortical left or right hemisphere brain damage had difficulty processing emotional words, facial expressions, and prosodic intonations. Subjects with cortical damage only, regardless of side of lesion (left or right), performed without significant difficulty across all tasks. There were hemispheric differences found in the cortical-subcortical groups. The left cortical-subcortical subjects had the greatest difficulty processing linguistic information and the right cortical-subcortical subjects had the most difficulty processing facial expression and prosodic information. Findings support the connection between higher- and lower-order brain structures in processing messages that are affectively coded.

Assessment in communication disorders: some observations on current issues

The assessment of communication disorders is, by necessity, a behavioural description process. Standardized measures provide quantitative data that contribute to the identification of communication disorders, but test scores and normative comparisons are insufficient for describing the effects of impairment on performance in communicative settings. The importance of ecological validity in tests for communication disorders, the need for systematic observation and the potential biases in testing diverse populations are considered within the framework of identification and differential diagnosis of speech and language disorders. There are also communicative disorders that are clinically recognized, but which cannot be reliably identified following standardized testing and systematic observation in communicative settings. For these disorders, there is a continuing need for research based on behavioural description to develop a theoretical understanding of the disorder that can guide reliable assessment, identification and intervention.