The first agonist and antagonist burst in patients with an upper motor neuron syndrome

Authors

  • S. Fagioli,

    1. Quinta Clinica Neurologica, Centro Disordini del Movimento, Dipartimento di Scienze Neurologiche, Universitá di Roma “La Sapienza,” Roma
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  • Dr. A. Berardelli,

    Corresponding author
    1. Quinta Clinica Neurologica, Centro Disordini del Movimento, Dipartimento di Scienze Neurologiche, Universitá di Roma “La Sapienza,” Roma
    • Quinta Clinta Neurologica, Viale dell, Universitá 30, 00185 Roma, Italia
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  • M. Hallett,

    1. National Institute of Neurological and Communicative Disorders and Stroke, Bethesda, Maryland, U.S.A.
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  • N. Accornero,

    1. Quinta Clinica Neurologica, Centro Disordini del Movimento, Dipartimento di Scienze Neurologiche, Universitá di Roma “La Sapienza,” Roma
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  • M. Manfredi

    1. Quinta Clinica Neurologica, Centro Disordini del Movimento, Dipartimento di Scienze Neurologiche, Universitá di Roma “La Sapienza,” Roma
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Abstract

Rapid elbow flexion movements were studied in patients with an upper motor neuron syndrome following a stroke. The velocity of movements was slower than normal. The initial bursts of electromyographic (EMG) activity in both the agonist and antagonist muscles were prolonged. As in normal subjects, the first agonist burst increased in duration with larger movements, but it generally remained about 40 ms longer than normal. The size of the first agonist burst also increased with larger movements. A fixed linkage between burst duration and level of motor unit recruitment, together with a deficient corticospinal command, could explain the prolonged burst duration with preserved ability to modulate the burst.

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