The ankle stretch reflexes in normal and spastic subjects: the response to sinusoidal movement

Forces and electromyograms were recorded during sinusoidal flexion-extension movements of normal and spastic ankle joints. Spastic subjects showed relatively stereotyped responses, with evidence of a vigorous spinal stretch reflex. The responses of normal limbs were variable; there was little reflex...

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Bibliographic Details
Published in:Brain (London, England : 1878) England : 1878), 1984-06, Vol.107 (2), p.637-654
Main Authors: RACK, P. M. H, ROSS, H. F, THILMANN, A. F
Format: Article
Language:English
Subjects:
Adolescent
Adult
Aged
Ankle - physiopathology
Biological and medical sciences
Child
Electromyography
Female
Humans
Leg
Male
Medical sciences
Middle Aged
Movement
Muscle Spasticity - physiopathology
Myoclonus - physiopathology
Nervous system (semeiology, syndromes)
Nervous system as a whole
Neurology
Paralysis - physiopathology
Reflex, Stretch
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Summary:Forces and electromyograms were recorded during sinusoidal flexion-extension movements of normal and spastic ankle joints. Spastic subjects showed relatively stereotyped responses, with evidence of a vigorous spinal stretch reflex. The responses of normal limbs were variable; there was little reflex response to the first cycles, but as the movement continued the reflex responses increased and often came to resemble the responses of spastic limbs. At some frequency between 3 and 7 Hz, the reflex response was so timed that it tended to assist rather than resist the movement; this was the frequency at which many subjects (normal, as well as spastic) exhibited spontaneous clonus if an appropriate load was attached to the foot. The frequency of this clonus changed with changes of load. It is concluded that whereas the gain of a normal stretch reflex may vary considerably, the stretch reflex of the spastic subject is set at one end of the normal range. With this high gain, the stretch reflex may support spontaneous clonus in both normal and spastic subjects.
ISSN:0006-8950
1460-2156
DOI:10.1093/brain/107.2.637