Motor excitability evaluation in developmental stuttering: a transcranial magnetic stimulation study.
BACKGROUND
Developmental stuttering (DS) is viewed as a motor speech-specific disorder, although several lines of research suggest that DS is a symptom of a broader motor disorder. We investigated corticospinal excitability in adult DS and normal speakers.


METHODS
Transcranial magnetic stimulation (TMS) was administered over left/right hand representation of the motor cortex while recording motor evoked potentials (MEPs) from the contralateral first dorsal interosseous (FDI) muscle. Resting, active motor thresholds, silent period threshold and duration were measured. A stimulus-response curve at resting was also obtained to evaluate MEP amplitudes.


RESULTS
Lower corticospinal responses in the left hemisphere of DS were found, as indicated by a reduction of peak-to-peak MEP amplitudes compared to normal speakers.


CONCLUSIONS
This provides further evidence that DS may be a general motor deficit that also involves motor non-speech-related structures. Moreover, our results confirm that DS may be related to left hemisphere hypoactivation and/or lower left hemisphere dominance. The present data and protocol may be useful for diagnosis of subtypes of DS that may benefit from pharmacological treatment by targeting the general level of cortical excitability.
DSBTA, Section of Human Physiology, University of Ferrara, Ferrara, Italy. pbusan@units.it
Pierpaolo
P
Busan
Alessandro
A
D'Ausilio
Massimo
M
Borelli
Fabrizio
F
Monti
Giovanna
G
Pelamatti
Gilberto
G
Pizzolato
Luciano
L
Fadiga
D000328:Adult; D004558:Electric Stimulation; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000502:physiology; D011712:Pyramidal Tracts / Q000503:physiopathology*; D013342:Stuttering / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation