The Electromyogram of Atrophic Muscles in Cases of Intramedullar Affections

Buohthal, Fritz; Clemmesen, Svend

doi:10.1111/j.1600-0447.1943.tb09281.x

Cited by 22 publications

(4 citation statements)

References 9 publications

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“…The unaffected, if any, plus the completely recovered anterior horn cells form the structural background for the remaining muscle tension. Secondary to the destruction of the anterior horn cells, however, the activity of the functioning motor units seems to be modified, as synchronized electromyographic recordings can be obtained from relatively large areas within the affected muscle (19,20). Most of the strength measurements were performed in accordance with standard procedures (1 7).…”

Section: Resultsmentioning

confidence: 99%

Fade in Voluntary Muscle Contractions of Patients with Sequelae after Poliomyelitis

Segher

1984

Acta Anaesthesiol Scand

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The isometric contraction pattern was followed in three female and two male patients with lower motoneuron paralysis due to sequelae from poliomyelitis in 1942-48. In uninstructed contractions, force increased slowly to an almost horizontal level which could be kept up for as long as desired. During rapid maximal voluntary contractions, a "biphasic" mechanogram was seen in 49% of 204 contractions, with a first maximum after 0.3 s (0.1-0.9), separated by a notch from a second maximum after 1.1 s (0.3-2.3). In the rest of the contractions, force could not be generated rapidly, despite the intention of the subjects, and a single maximum in the mechanogram was seen after 0.9 s (0.2-2.4). In contractions where a biphasic contraction pattern was seen, the electromyographic activity was greatest during approximately the first one half second of the contraction. In the other contractions the electromyographic activity was about the same during the whole contraction. The results suggest that the mechanograms are composed of a high innervation threshold, fast phasically active component, and a low innervation threshold, slow tonically active component. Fade represents the waning of tension in the phasically active component present in some contractions, while this component appears to be eliminated by poliomyelitis in other muscle contractions.

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Section: Resultsmentioning

confidence: 99%

Fade in Voluntary Muscle Contractions of Patients with Sequelae after Poliomyelitis

Segher

1984

Acta Anaesthesiol Scand

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“…However, in case of motor neuron disorders involving anterior horn cells, such as poliomyelitis, EMG recordings show large synchronous waves. Motor unit action potentials recorded from different parts of a muscle show high synchrony (Buchthal and Clemmeson 1943).…”

Section: Discussionmentioning

confidence: 99%

An oscillator theory of motor unit recruitment

Prashanth

Chakravarthy

2007

Biol Cybern

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The phenomenon of systematic recruitment of motor units with increasing demand load is usually explained by the size principle. Though this principle successfully explains the gain-related aspects of muscle force generation, it does not address the need for desynchronization of motor unit activities in order to produce a smooth tension profile at the level of whole muscle, while individual muscle fibers are "twitching." We propose an oscillator model of motor neurons in which a pool of motor neurons fires a bundle of muscle fibers. Although individual muscle fibers have a complicated tension profile, the tension produced by the entire bundle is regulated and follows a command signal accurately. This is shown to be possible because of uncorrelated activity produced by local inhibitory connections among motor neurons. Connections that produce synchronized oscillations result in uncontrolled contractions of the muscle. These results seem to suggest that while synchronized activity indicates pathology and disease, desynchronized activity is the precondition for normal muscle function. Physiological evidence for the proposed theory of motor unit synchronization is presented.

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“…(3) Synchronization of motor unit activity. The recognition of synchronization was first applied to clinical work by Buchthal and Clemmesen [6] who suggested that its cause was the spread of impulses from one neurone to an adjoining neurone in the cord. More recently, Denny-Brown [7] has suggested that the phenomenon of synchronization is not due to synchronous contraction of two or more motor units, but to the detection by two or more needle electrodes of the same large unit.…”

mentioning

confidence: 99%

Clinical Electromyography in the Royal Air Force

At¹

1949

Proceedings of the Royal Society of Medicine

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The Electromyogram of Atrophic Muscles in Cases of Intramedullar Affections

Cited by 22 publications

References 9 publications

Fade in Voluntary Muscle Contractions of Patients with Sequelae after Poliomyelitis

Fade in Voluntary Muscle Contractions of Patients with Sequelae after Poliomyelitis

An oscillator theory of motor unit recruitment

Clinical Electromyography in the Royal Air Force

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