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Real-time magnetic resonance imaging reveals hyper-and hypokinetic articulators in stuttering

Poster C68 in Poster Session C, Wednesday, October 25, 10:15 am - 12:00 pm CEST, Espace Vieux-Port

Martin Sommer¹, Lea Ufermann¹, Marius Hergt¹, Alexandra Korzeczek¹, Daniela Ponssen¹, Annika Primassin², Arun Joseph³, Walter Paulus⁴, Mathias Bähr¹, Nicole Neef⁵, Jens Frahm³; ¹University of Göttingen, ²FH Münster University of Applied Sciences, Fachbereich Gesundheit, Münster, Germany, ³Biomedical NMR, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany, ⁴Department of Neurology, LMU Hospital, LMU, Munich, Germany;, ⁵., Department of Diagnostic and Interventional Neuroradiology, University Medical Center Göttingen, Göttingen, Germany

Real-time magnetic resonance imaging (rtMRI) improves the visualization of movement patterns of inner articulators. Here we sought to reveal atypical invisible articulatory movements of inner articulators in persistent developmental stuttering during fluent and dysfluent non-word production.Sixteen fluent speakers (FS) and 18 adults who stutter (AWS) read the non-words [gakʃaitidɔyk] and [natʃaitidɔyt] while supine in a 3T rtMRI. We recorded a midsagittal cross-sectional plane covering mouth, mandibular nasal cavities, pharynx, and larynx at 55 frames per second. For each non-word, we qualitatively characterized the movements of articulators in FS in meticulous detail. We then analyzed events unequivocally stuttered. We observed dysfluent productions of [gakʃaitidɔyk] and [natʃaitidɔyt] in 15 of 18 AWS. After careful exclusion of other dysfluencies, 54 stuttering events from 9 AWS and 45 stuttering events from 6 AWS remained for the qualitative analysis of [gakʃaitidɔyk] and [natʃaitidɔyt], respectively. We assessed five articulatory components, i.e., lips, velum, tongue tip, tongue body, and tongue radix. Having described an abnormal movement pattern, each rater (L.U. and M.H.) went back to video clips of four randomly selected FS. We checked again whether any trace of the movement abnormality seen in AWS could be detected in FS. We calculated odds ratios for each abnormal movement pattern to occur at a stuttering symptom compared to another stuttering symptom using a mixed-model binary logistic regression. During stuttered events in AWS, we observed sustained contractions of the tongue tip, resembling dystonia; tremor of the tongue body with an average frequency of 6 Hz; and spurious, mostly isometric contractions of the tongue or velum. These movements were unevenly distributed and partially matched the stuttering symptom: Tremor was mainly observed during repetitions. The odds to observe a tremor was 109 times higher when the stuttering symptom was a repetition compared to when it was a silent block. Sustained contractions and spurious movements were observed with repetitions, prolongations, and silent blocks. An odds ratio analysis linked the extra movements to silent blocks rather than repetitions. None of the deviant movement patterns was observed in four randomly selected FS. rtMRI enables unprecedented insights into the morphology of stuttering, which comprises all three typical categories of movement disorders (hyperkinetic, dystonic, and hypokinetic). Dystonia-like sustained movements and tremor point to an involvement of the basal ganglia. This methodological breakthrough emphasizes the neurogenic component of stuttering and gives rise to classifying developmental stuttering as a movement disorder.

Topic Areas: Speech Motor Control,