The H Reflex in Normal, Spastic, and Rigid Subjects

Angel, Ronald W.; Hofmann, William W.

doi:10.1001/archneur.1963.00460060021002

Cited by 208 publications

(84 citation statements)

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“…20,21 Electrophysiologic parameters are objective but there is some controversy regarding the usefulness of these parameters in evaluating spasticity. Although both H/M ratio and F/M ratio have been reported to assess either the spinal segmental re¯ex or excitability of the anterior horn cells, 22,23 there are studies reporting that they were increased in subjects with decreased muscle stretch re¯ex. 24,25 Little et al 26 reported that these ratios were useful methods in evaluating spasticity when measured serially.…”

Section: Discussionmentioning

confidence: 99%

Effect of cold air therapy in relieving spasticity: applied to spinalized rabbits

2002

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Study design: Before-After trial measured prior to cold air therapy, immediately following, after 30 and 60 min. Objective: To determine the eect of cold air therapy in relieving spasticity, the optimal intramuscular temperature, and the duration of spasticity relief attained by cold air therapy. Setting: Clinical research laboratory, Seoul, Korea. Subject: Forty-six spastic paraplegic rabbits with spinal cord injury. Methods: Spastic paraplegia was induced by transection of spinal cord in 46 rabbits. Cold air was applied to triceps surae muscles for 30 min at three dierent intramuscular temperatures (25, 30 and 32.58C). Clinical parameters of spasticity (muscle tone, Babinski's sign, muscle stretch re¯ex and ankle clonus) and electrophysiologic parameters (F/M ratio and H/M ratio) were measured immediately following, after 30 and 60 min. Results: In the 32.58C group, relief in spasticity lasted less than 30 min. In the 30 and 258C groups, the decrease in spasticity lasted for at least 30 min clinically. The spasticity relief was observed only immediately following treatment when measured electrophysiologically. However, six out of 16 cases (37.5%) in the 258C group showed complete motor conduction block. Conclusion: To relieve spasticity with cold air therapy, the intramuscular temperature should be maintained at 308C. The duration of spasticity relief lasted from between 30 ± 60 min after cold air therapy.We certify that all applicable institutional and governmental regulations concerning the ethical use of animals were followed during the course of this research.

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Section: Discussionmentioning

confidence: 99%

Effect of cold air therapy in relieving spasticity: applied to spinalized rabbits

2002

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“…10 One measure used by numerous investigators to quantify hyper-reflexia is the electrical analogue of the classic tendon jerk reflex, referred to as the Hoffman or H-reflex. 2,[15][16][17][18][19] The H-reflex is a compound electromyographic (EMG) response elicited by the synaptic activation of motoneurons by muscle afferents following stimulation of muscle nerves. Thompson et al 20 investigated four measures of H-reflex excitability in a contusion model of SCI in the rat.…”

Section: Introductionmentioning

confidence: 99%

Restoration of frequency-dependent depression of the H-reflex by passive exercise in spinal rats

et al. 2005

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“…Previous comparisons of the H reflex amplitude in normal and rigid subjects have failed to show any abnormality (Angel and Hofmann, 1963;Dietrichson, 1971) but the AJ/H response ratio was found to be increased by Dietrichson (1971) despite normal H responses and the fact that the mechanical threshold of rigid subjects was normal. In the latter study, the control subjects were considerably younger than the patients and the measured maximal AJ and H amplitudes were given, rather than the ratio between the mean of a series of H responses and the M response.…”

Section: Tonic Activation: Resultsmentioning

confidence: 99%

Dynamic spindle reflexes and the rigidity of Parkinsonism

McLellan

1973

Journal of Neurology, Neurosurgery & Psychiatry

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SUMMARY The effects of stimulating the reflex arc from dynamic spindle endings were examined in patients with the rigidity of Parkinsonism and in control subjects. The arc was activated phasically by a tendon tap and by electrical stimulation in 15 patients. The effect of reinforcement by Jendrassik's manoeuvre was observed. The response to phasic activation indicated central facilitation of the reflex loop in the patients with Parkinsonism, with a concurrent decrease in fusimotor drive to dynamic spindles. These abnormalities could not be correlated with the severity of the patients' rigidity, and they did not alter when the rigidity was reduced by levodopa. The effect of activating dynamic spindle endings tonically by vibration at 50 Hz was also examined. The reflex contraction of the biceps and triceps muscles in response to vibration was found to be increased in 24 patients with rigidity compared with 24 control subjects. Patients with severe rigidity developed a more powerful contraction in response to vibration than patients with mild rigidity. The response to vibration was reduced by treatment with levodopa but the amount of this reduction could not be correlated with changes in the patients' rigidity.Rigidity is a clinical term used to indicate an increased resistance of muscle to passive stretch, the resistance being approximately constant throughout the range of stretching. DennyBrown (1960) has pointed out that when a rigid limb is fully supported and the patient relaxed, the rigidity disappears and unimpaired passive movement is possible in either direction within a range of 5-10°. Movement of a larger range sets up a contraction in the stretched muscle which is maintained as the movement continues, showing that rigidity is a stretch reflex activated by sensory receptors in the muscle. Sensory nerve fibres from primary muscle spindle organs are known to connect monosynaptically with alpha motoneurones serving related extrafusal muscle fibres. It is therefore possible that activation of primary spindle organs initiates the reflex contraction responsible for the phenomenon of rigidity. This would imply abnormal functioning of the reflex loop and the purpose of the present 1 Present address:

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The H Reflex in Normal, Spastic, and Rigid Subjects

Abstract: The H reflex has been widely used in the study of human physiology, both normal 3,6,11,13,18,19 and abnormal.12,14,15,16,

Cited by 208 publications

References 10 publications

Effect of cold air therapy in relieving spasticity: applied to spinalized rabbits

Effect of cold air therapy in relieving spasticity: applied to spinalized rabbits

Restoration of frequency-dependent depression of the H-reflex by passive exercise in spinal rats

Dynamic spindle reflexes and the rigidity of Parkinsonism

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