Profile of speech and language characteristics in pediatric demyelinating diseases
Balakrishnan, Lakshmi Nisha
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Purpose: The current study aimed to investigate the speech and language abilities in adolescents with demyelinating diseases. The relationship of speech and language deficits to neurocognitive deficits as well as disease characteristics was also explored. Methods: 12 participants with a medical diagnosis of a demyelinating disease, aged 13 to 18 years participated. Medical records were reviewed to characterize participants. Neuropsychological measures, administered by a pediatric neuropsychologist, were reported. The speech-language battery included an expository language sample, a sentence production task, a maximum repetition rate (MRR) task and a sustained phonation task. From the expository language samples, language measures of total number of T-units, mean length of T-units, and clausal density were determined. Speech measures included word sequence durations (seconds), maximum repetition rate (syllables/second), speaking rate (syllables/second), and sustained phonation (seconds). Coefficients of variation for word sequence durations were determined to provide a measure of temporal variability. Participants’ performance was compared to normative data in the literature. Data were analyzed using a variety of descriptive and non-parametric statistics wherever possible. Results and Discussion: Participants demonstrated deficits in numerous neurocognitive domains, but particularly in speed of processing and executive functioning. Eighty three percent of the participants did not demonstrate any language deficits. Seventeen percent of the participants demonstrated linguistic difficulties on the measures of syntactic complexity. The high occurrence of pronoun errors in one participant, in the absence of apparent deficits on the reported language measures, suggests that error analysis, including cohesion analysis, may be an alternative method of detecting subtle language deficits or differences. Compared to normative data, participants demonstrated word sequence durations that were significantly slower in the simple context and more variable in the complex context. Participants also produced word sequences faster when embedded in a longer and more complex sentence than when produced in isolation, suggesting the use of an adult-like speech motor planning strategy, albeit in a more temporally variable way. Fifty eight percent of the participants had slow MRRs, which is suggestive of motor speech deficits. Eighty three percent of the participants also demonstrated slow speaking rates in their expository language samples. This likely reflects a combination of motoric factors and cognitive-linguistic processing difficulties. Most participants performed within normal limits on the sustained phonation task. Owing to the coarse nature of this measure, no strong conclusions can be made about the respiratory and phonatory functioning of participants in the current study. A clear relationship between the neuropsychological and speech-language measures was not apparent. No strong conclusions about the relationship between disease characteristics and speech-language skills could be made. Thus, adolescents with demyelinating diseases demonstrated deficits on a variety of speech and language measures, especially on the temporal measures of speech. Owing to active disease processes during the sensitive phase of development, adolescents with demyelinating diseases may be at an increased risk for motor speech disorders and subtle linguistic deficits. Findings suggest that there is a need to enhance our knowledge of the nature of potential speech and language deficits in this clinical group to guide assessment and intervention, if and when needed.