Normal intracortical excitability in developmental stuttering.
Persistent developmental stuttering (PDS) shares clinical features with task-specific dystonias. In these dystonias, intracortical inhibition is abnormally weak. We therefore sought to determine intracortical inhibition and intracortical facilitation in PDS. In 18 subjects with PDS since childhood (mean age, 39.4 [SD 13.0] years) and 18 speech-fluent controls (43.6 [14.3] years), we investigated resting and active motor thresholds as well as intracortical inhibition and facilitation of the optimal representation of the abductor digiti minimi of the dominant hand using transcranial magnetic stimulation. In PDS, the resting and active motor thresholds were increased, whereas intracortical inhibition and facilitation were normal. Normal intracortical excitability makes a pathophysiological analogy between focal dystonia and PDS less likely. The enhanced motor threshold suggests reduced motor cortical neuronal membrane excitability in PDS.
Sommer
Martin
M
Department of Clinical Neurophysiology, University of Göttingen, Göttingen, Germany. msommer@gwdg.de
Wischer
Stephan
S
Tergau
Frithjof
F
Paulus
Walter
W
D000328:Adult; D002540:Cerebral Cortex / Q000503:physiopathology*; D004558:Electric Stimulation; D004574:Electromagnetic Fields; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation; D009433:Neural Inhibition / Q000502:physiology*; D012016:Reference Values; D012684:Sensory Thresholds / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D013342:Stuttering / Q000503:physiopathology*; D009435:Synaptic Transmission / Q000502:physiology