Motor excitability in myopathy.
OBJECTIVE
To explore whether patients with myopathy present changes in motoneuronal excitability.


METHODS
Patients with well-defined myopathies were studied with single and paired pulse transcranial magnetic stimulations and electrical nerve stimulations to explore neuronal motor excitability. Motor-evoked potentials were recorded from the clinically unaffected first dorsal interosseous muscle (n=10) and the paretic deltoid muscle (n=8).


RESULTS
Compared to an age-matched healthy control group, myopathic patients showed a reduction of intracortical inhibition, enhancements of alpha-motoneuron excitability and increased amplitudes of motor-evoked potentials during target muscle contraction. These alterations were present in clinically affected and clinically unaffected muscles.


CONCLUSIONS
In myopathy, nervous system excitability may be altered, presenting as a motor disinhibition on cortical and subcortical levels.
Liepert
Joachim
J
Department of Neurology, University of Hamburg, University Hospital Eppendorf, Martini Strasse 52, D-20246 Hamburg, Germany. liepert@uke.uni-hamburg.de
Schoser
Benedikt G H
BG
Weiller
Cornelius
C
D000293:Adolescent; D000328:Adult; D000375:Aging / Q000502:physiology; D004558:Electric Stimulation; D004576:Electromyography; D004594:Electrophysiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000503:physiopathology; D009135:Muscular Diseases / Q000503:physiopathology*; D009136:Muscular Dystrophies / Q000503:physiopathology; D020391:Muscular Dystrophy, Facioscapulohumeral / Q000503:physiopathology; D009431:Neural Conduction / Q000502:physiology; D012727:Sex Characteristics; D014459:Ulnar Nerve / Q000503:physiopathology