Vergleich der Artikulationsmuster von stotternden und nicht stotternden Probanden anhand der Echtzeit-Magnetresonanz-Tomographie
Comparison of the articulation patterns of stuttering and nonstuttering subjects using real-time magnetic resonance imaging
by Lea Ufermann
Date of Examination:2025-01-10
Date of issue:2024-12-09
Advisor:Prof. Dr. Martin Sommer
Referee:Prof. Dr. Martin Sommer
Referee:PD Dr. Peter Dechent
Persistent Address:
http://dx.doi.org/10.53846/goediss-10924
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Abstract
English
The original neurogenic non-syndromic stuttering begins in early childhood and can persist into adulthood. Its characteristic symptoms are repetition of sounds and syllables, prolongation of sounds, blocking and a variety of accompanying symptoms. Its average prevalence is about 1%. Its average incidence is about 5%. Spontaneous remission is observed in about 75% of all children who stutter an girls recover more often than boys. Early identification increases the chances of successful therapy. Stuttering modification, fluency shaping and the Lidcombe program are considered to be effective therapy methods. The present research investigated stuttering speech according to the hypotheses 1) that altered articulator movement sequences are likely during stuttering, 2) that these movement deviations are related to specific stuttering symptoms, and 3) that these conspicuous movement patterns are not found in fluent speaking control subjects. The snapshot-flash technique used by Jens Frahm and colleagues from Göttingen displayed the articulation of fluent speakers and stuttering speakers in real time and enabled the author to make a descriptive comparison of the two groups. The adults who stuttered and the control subjects were critically examined according to predefined objective criteria. A total of nine stuttering adults were examined during stuttering speech. After excluding two subjects, the control group comprised 14 fluent speakers. None of the fluent speakers stuttered. The analysis focused on the pseudoword “gakscheitideuk”, which contained velar, alveolar and postalveolar sounds that enabled an analysis of internal articulators with a focus on the tongue and soft palate. The first step was to analyze the control subjects´ fluent speech in text form, which gave the author a basic understanding of the articulatory movements. Then the pseudoword was analyzed in 54 stuttered runs with the help of previously defined coding levels. This was followed by a tabular evaluation of the analysis, as well as the determination of the tremor frequency of certain articulation movements and the statistical analysis, using descriptive statistics and binary logistic regression analysis. Within the stuttering speech of stuttering subjects, the stuttering symptoms repetition and silent block were evident. During their articulation, more stuttering adults showed only silent blocks or a combination of silent blocks and repetitions and only two stuttering adults showed only repetitions. In comparison, the articulators of stuttering adults clearly showed deviations from the normal speech flow of fluent speakers. The stuttering was characterized by movement patterns which were not found in the four randomly selected fluent speakers. These deviations could be divided into 3 main categories: (1) isometric movements, (2) tremor and (3) dystonia. All three forms of the classic movement disorder, namely hyperkinesis, hypokinesia and dystonia, were found. The tremor was characterized by repetitive movements of the tongue with an average frequency of 6.0 +/- 2.3 Hz. During the analysis, it became clear that several movement patterns can occur within one stuttering symptom. On the one hand, the individual movement patterns can be observed with different stuttering symptoms. There were hypokinetic movement segments that led to a standstill of the movement and to an interruption of speech. There was a higher chance of their occurrence if the articulated stuttering symptom was a silent block as opposed to a repetition. On the other hand, the odds ratio of being able to observe repetitive movements in a stuttering subject was higher if he articulated the stuttering symptom repetition. In addition, changes in the shape of the tip of the tongue were observed, which resembled dystonic movements and could be due to insufficient environmental inhibition, previously described in a study as reduced intracortical inhibition in stutterers. As the research presented here shows, ultimately only an intensive examination of stuttering speech itself can lead to an understanding of the moments and progression of stuttering. One of the worlds largest data sets of stuttering speech in the form of real-time MRI video sequences as the basis of this research has given an unprecedented insight into the dynamic process of speech production in stutterers. The author´s research leads to results that are consistent with an even go far beyond previous findings on the impairment of speech motor initiation in stutterers. It can be clearly shown that stuttering speakers differ in their articulatory movements from those of fluent speakers. The present research thus expands our understanding of stuttering speech by shedding light on the neurogenetic component of stuttering and by making a substantial contribution to the classification of developmental stuttering as a movement disorder.
Keywords: stuttering; stuttering modification; real-time MRI
