Classification of Dysarthria in Polish TBI patients

Monika Połczyńska-Fiszer (Adam Mickiewicz University), Anna Pufal (Collegium Medicum UMK, Bydgoszcz)

Traumatic brain injury (TBI) and prolonged coma result in various neurological dysfunctions, including speech dysarthria. Dysarthria is a speech impairment which is caused by a disruption of motor speech execution, subserved by the basal ganglia and cerebellar control circuits (cf. Ackermann et al. 1999; Spencer and Rogers 2005). It occurs in degenerative diseases involving the cerebellum, Parkinson's disease, cerebrovascular accidents and close head injuries, less commonly- in encephalitis and brain tumors (cf. Ziegler 2002). It affects breathing, sound producion in the larynx area, resonance, articulation, prosody and rhythm. The disorder is universal but it can also be language specific. There are very few publications devoted to the phenomenon in Polish. The dual aim of the present study is to analyse the characteristics of dysarthric speech of Polish TBI patients, as well as to establish a simple questionnaire that could be used by speech therapists to estimate type and degree of dysarthria in Polish. The existing clinical tests used to assess the degree of dysarthria are long, which leads to the patient's fatigue that may considerably distort final results. 15 post-coma subjects with severe close head injury (mean age: 30 years) participated in the experiment. According to the level of intelligibility, there were 5 individuals with light dysarthria, 5 with moderate, and 5 with severe dysarthria. Both standard and non-standard tests were used to record the patients' utterances. 5 aspects of speech were investigated with a programme used for speech analysis, Praat: rate, intonation, rhythm, intensity and articulation of phonemes. On the basis of the findings which revealed significant sound quality variations among the subjects, the authors propose the following classification of dysarthria in Polish:

1. Light - slow, intelligible speech with inaccurate articulation of fricative sounds, changes in intonation, rate and rhythm, often intensified by fatigue;

2. Moderate - mumble that is difficult to comprehend, the pronunciation of some vowels and the majority of consonants being heavily impaired, especially that of the trill /r/ which appears the lastest in the ontogenesis;

3. Advanced - single vowels with distorted articulation, usually a sound close to Polish /a/.

The results of the research support the hypothesis that an individual who has lost the ability to speak undergoes at least the major phases of first language acquisition ontogenesis.

References

Ackermann, H., Gräber, S., Hertrich, I. and I. Daum. 1999. Phonemic Vowel Lenght Contrasts in Cerebellar Disorders. Brain and Language 67. Amsterdam: Elsevier. 95-109.

Spencer, K. A. and M. A. Rogers. 2005. Speech motor programming in hypokinetic and ataxic dysarthria. Brain and Language 94. Amsterdam: Elsevier. 347-366.

Ziegler, W. 2002. Task-related Factors in Oral Motor Control: Speech and Orad Diadochokinesis in Dysarthria and Apraxia of Speech. Brain and Language 80. Amsterdam: Elsevier. 556-575.