Stretch reflexes of the proximal arm in a patient with mirror movements: absence of bilateral long-latency components

The stretch reflex responses evoked by unilateral limb displacement in distal (first dorsal interosseus (FDI)) and in proximal (biceps brachii (Bb)) arm muscles were studied during matched bilateral contractions in a patient with congenital mirror movements. In this patient unilateral transcortical...

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Bibliographic Details
Published in:Electroencephalography and clinical neurophysiology 1996-04, Vol.101 (2), p.79-83
Main Authors: Fellows, S.J., Töpper, R., Schwarz, M., Thilmann, A.F., Noth, J.
Format: Article
Language:English
Subjects:
Adult
Arm - physiology
Biological and medical sciences
Electromyography
Hand - physiology
Human
Humans
Long latency
Male
Medical sciences
Movement Disorders - physiopathology
Muscle Relaxation - physiology
Muscle, Skeletal - physiology
Nervous system (semeiology, syndromes)
Nervous system as a whole
Neurology
Reflex - physiology
Stretch reflex
Time Factors
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Summary:The stretch reflex responses evoked by unilateral limb displacement in distal (first dorsal interosseus (FDI)) and in proximal (biceps brachii (Bb)) arm muscles were studied during matched bilateral contractions in a patient with congenital mirror movements. In this patient unilateral transcortical magnetic stimulation (TMS) elicited not only the normal contralateral EMG response but also a clear ipsilateral component in the EMG of both proximal and distal arm muscles. As expected from previous studies, the ipsilateral FDI muscle responded to stretch of the index finger with short- (M1) and long-latency (M2) reflex components. In addition, the FDI contralateral to displacement exhibited an abnormal mirrored response corresponding to the M2 interval. In contrast, whereas the ipsilateral Bb responded to imposed elbow extension with a marked M1/M2 reflex response, no mirroring of either reflex component was apparent in the contralateral Bb EMG. If the mirroring of the M2 in the FDI is accepted as evidence for the transcortical nature of the M2 reflex response, then it follows that the absence of such mirroring in the Bb indicates that a transcortical mechanisms cannot play a major role in the generation of long-latency stretch reflex responses in proximal arm muscles.
ISSN:0924-980X
0013-4694
1872-7093
DOI:10.1016/0924-980X(95)00247-I