Motor excitability evaluation in developmental stuttering: A transcranial magnetic stimulation study

Busan, Pierpaolo; D'Ausilio, Alessandro; Borelli, Massimo; Monti, Fabrizio; Pelamatti, Giovanna; Pizzolato, Gilberto; Fadiga, Luciano

doi:10.1016/j.cortex.2011.12.002

Article in Press

Motor excitability evaluation in developmental stuttering: A transcranial magnetic stimulation study

Pierpaolo Busan
- DSBTA, Section of Human Physiology, University of Ferrara, Ferrara, Italy
- Department of Medical, Surgical and Healthy Sciences, University of Trieste, Trieste, Italy
- Corresponding author. Department of Medical, Surgical and Healthy Sciences, University of Trieste, Strada di Fiume 447, 34100 Trieste, Italy.
Alessandro D'Ausilio
- DSBTA, Section of Human Physiology, University of Ferrara, Ferrara, Italy
- IIT, The Italian Institute of Technology, Genoa, Italy
Massimo Borelli
- B.R.A.I.N. Centre for Neuroscience, Department of Life Sciences, University of Trieste, Trieste, Italy
Fabrizio Monti
- Department of Medical, Surgical and Healthy Sciences, University of Trieste, Trieste, Italy
Giovanna Pelamatti
- Department of Psychology, University of Trieste, Trieste, Italy
Gilberto Pizzolato
- Department of Medical, Surgical and Healthy Sciences, University of Trieste, Trieste, Italy
Luciano Fadiga
- DSBTA, Section of Human Physiology, University of Ferrara, Ferrara, Italy
- IIT, The Italian Institute of Technology, Genoa, Italy

Received 29 December 2010; received in revised form 15 July 2011; accepted 7 December 2011. published online 09 January 2012.
Corrected Proof

Reviewed 25 March 2011. Action editor Pia Rotshtein

Abstract

Introduction

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.

Keywords: Left hemisphere, Motor deficit, Motor evoked potentials, Pharmacological treatment of stuttering, Stuttering