Changes in motor cortex excitability during muscle fatigue in amyotrophic lateral sclerosis.
To further investigate the pathophysiology of amyotrophic lateral sclerosis (ALS), the silent period (SP) evoked by transcranial magnetic stimulation during a fatiguing muscle contraction was evaluated in 15 patients and in 15 healthy subjects. Physiological lengthening of the SP duration was not observed in patients with disease duration of > or = 2 years. Decreased intracortical inhibition, probably secondary to dysfunction of the inhibitory interneurons that modulate the corticomotoneuronal firing, appears in later stages of disease. Normal motor cortex adaptation is impaired and cortical hyperexcitability might be unmasked during fatigue in ALS patients with longer disease duration.
Nardone
R
R
Department of Neurology, 'F.Tappeiner' Hospital, Merano, Via Rossini, 5, 39012 Merano (BZ), Italy. raffaele.nardone@asbmeran-o.it
Buffone
E
E
Florio
I
I
Tezzon
F
F
D000328:Adult; D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000503:physiopathology*; D016022:Case-Control Studies; D018450:Disease Progression; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000473:pathology / Q000502:physiology*; D018763:Muscle Fatigue; D013997:Time Factors