Abstract
PurposeChildhood onset speech fluency disorder (stuttering) is possibly related to dopaminergic dysfunction. Mesencephalic hyperechogenicity (ME) detected by transcranial ultrasound (TCS) might be seen as an indirect marker of dopaminergic dysfunction. We here determined whether adults who stutter since childhood (AWS) show ME.MethodsWe performed TCS in ten AWS and ten matched adults who never stuttered. We also assessed motor performance in finger tapping and in the 25 Foot Walking test.ResultsCompared to controls, AWS showed enlarged ME on either side. Finger tapping was slower in AWS. Walking cadence, i.e., the ratio of number of steps by time, tended to be higher in AWS than in control participants.DiscussionThe results demonstrate a motor deficit in AWS linked to dopaminergic dysfunction and extending beyond speech. Since iron deposits evolve in childhood and shrink thereafter, ME might serve as an easily quantifiable biomarker helping to predict the risk of persistency in children who stutter.
Highlights
Stuttering is a speech fluency disorder with involuntary repetitions of syllables and sounds, prolongations of sounds and blockages (American Psychiatric Association, 2013)
(4) Several fMRI studies report an altered involvement of the substantia nigra (SN) in speech and motor tasks and a correlation between SN activity and stuttering severity (Giraud et al, 2008; Watkins et al, 2008; Metzger et al, 2018)
Even though the impairment in stuttering is clinically taskspecific and confined to speech fluency, detailed observation of hand motor tasks did reveal subtle impairments, too (Webster and Ryan, 1991; Zelaznik et al, 1994). This points to a more generalized motor problem, and motivated us to study basic motor behavior of hand function and walking in our sample, with the intention to correlate this with ultrasound findings on the one hand and severity of stuttering on the other hand
Summary
The results demonstrate a motor deficit in AWS linked to dopaminergic dysfunction and extending beyond speech.
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