OBJECTIVE: The influence of muscle vibration (MV) as a strong proprioceptive input on motorcortical excitability was studied in 5 patients with musician's cramp, 5 musician controls and 5 non-musician controls. METHODS: The relaxed flexor carpi radialis (FCR), involved in the dystonic movement in all patients, was vibrated using low frequency (80 Hz) and low amplitude (0.5 mm). Transcranial magnetic stimulation (TMS; intensity, 120% of motor threshold) was applied without MV, 3 and 9 s after the onset of MV. Motor-evoked potentials (MEPs) in the FCR and in the antagonistic extensor carpi radialis (ECR) were recorded. RESULTS: With MV, musician and non-musician controls showed a facilitation of MEPs in the FCR and a decrease of MEPs in the ECR. In musician's cramp, both phenomena were significantly less pronounced. CONCLUSIONS: The reduced facilitation of MEPs in musician's cramp indicates a reduced MV-induced activation of motorcortical areas representing the FCR. The less pronounced inhibition by MV reflects a reduced inhibitory control of the antagonistic ECR. As there were no differences between musician and non-musician controls, the observed changes in musician's cramp refer to this special form of focal dystonia. An impairment of focused motorcortical activation by proprioceptive input from a muscle involved in the dystonic movement is suggested.
OBJECTIVE: The influence of muscle vibration (MV) as a strong proprioceptive input on motorcortical excitability was studied in 5 patients with musician's cramp, 5 musician controls and 5 non-musician controls. METHODS: The relaxed flexor carpi radialis (FCR), involved in the dystonic movement in all patients, was vibrated using low frequency (80 Hz) and low amplitude (0.5 mm). Transcranial magnetic stimulation (TMS; intensity, 120% of motor threshold) was applied without MV, 3 and 9 s after the onset of MV. Motor-evoked potentials (MEPs) in the FCR and in the antagonistic extensor carpi radialis (ECR) were recorded. RESULTS: With MV, musician and non-musician controls showed a facilitation of MEPs in the FCR and a decrease of MEPs in the ECR. In musician's cramp, both phenomena were significantly less pronounced. CONCLUSIONS: The reduced facilitation of MEPs in musician's cramp indicates a reduced MV-induced activation of motorcortical areas representing the FCR. The less pronounced inhibition by MV reflects a reduced inhibitory control of the antagonistic ECR. As there were no differences between musician and non-musician controls, the observed changes in musician's cramp refer to this special form of focal dystonia. An impairment of focused motorcortical activation by proprioceptive input from a muscle involved in the dystonic movement is suggested.
Authors: Janey Prodoehl; Daniel M Corcos; Sue Leurgans; Cynthia L Comella; Annette Weis-McNulty; Colum D MacKinnon Journal: J Mot Behav Date: 2008-07 Impact factor: 1.328
Authors: Sarah Pirio Richardson; Barbara Bliem; Bernhard Voller; Nguyet Dang; Mark Hallett Journal: Exp Brain Res Date: 2008-10-21 Impact factor: 1.972