Flexor Carpi Radialis H-reflex in Normal Subjects and Hemiplegic Patients

ABSTRACT:Hoffmann (H) reflexes were elicited from the soleus muscle during treadmill walking in 21 spastic paretic patients. The soleus and tibialis anterior muscles were reciprocally activated during walking in most patients, much like that observed in healthy individuals. The pattern of H-reflex modulation varied considerably between patients, from being relatively normal in some patients to a complete absence of modulation in others. The most common pattern observed was a lack of H-reflex modulation through the stance phase and slight depression of the reflex in the swing phase, considerably less modulation than that of normal subjects under comparable walking conditions. The high reflex amplitudes during periods of the step cycle such as early stance seems to be related to the stretch-induced large electromyogram bursts in the soleus in some subjects. The abnormally active reflexes appear to contribute to the clonus encountered during walking in these patients. In three patients who were able to walk for extended periods, the effect of stimulus intensity was examined. Two of these patients showed a greater degree of reflex modulation at lower stimulus intensities, suggesting that the lack of modulation observed at higher stimulus intensities is a result of saturation of the reflex loop. In six other patients, however, no reflex modulation could be demonstrated even at very low stimulus intensities.

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The H-reflex of the flexor carpi radialis muscle; a study in controls and radiation-induced brachial plexus lesions.

Journal of Neurology Neurosurgery & Psychiatry ◽

10.1136/jnnp.47.10.1098 ◽

1984 ◽

Vol 47 (10) ◽

pp. 1098-1101 ◽

Cited By ~ 19

Author(s):

B W Ongerboer de Visser ◽

R J Schimsheimer ◽

A A Hart

Keyword(s):

Brachial Plexus ◽

H Reflex ◽

Flexor Carpi Radialis ◽

Radiation Induced ◽

Flexor Carpi Radialis Muscle

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Phase-Dependent Inhibition of H-Reflexes During Walking in Humans Is Independent of Reduction in Knee Angular Velocity

Journal of Neurophysiology ◽

10.1152/jn.1999.82.2.747 ◽

1999 ◽

Vol 82 (2) ◽

pp. 747-753 ◽

Cited By ~ 25

Author(s):

M. Garrett ◽

T. Kerr ◽

B. Caulfield

Keyword(s):

Angular Velocity ◽

Knee Joint ◽

Soleus Muscle ◽

Normal Subjects ◽

Afferent Input ◽

H Reflex ◽

Short Latency ◽

Reflex Modulation ◽

Reflex Responses ◽

Knee Movement

The purpose of this investigation was to investigate whether reduction in impulses arising from stretch of the quadriceps by restricting rapid knee flexion in early swing would affect inhibition of the H-reflex during swing. The contribution of afferent input arising from knee angular velocity to phase-dependent modulation of short-latency responses in the soleus was studied by simultaneously measuring joint velocity and soleus H-reflex responses at midstance and midswing phases of treadmill walking in 15 normal subjects. Stimulus strength was varied so that both maximal M and H waves were identified in each subject at midswing and midstance with the knee unrestricted (UK) and with knee movement restricted (RK), using a full leg bivalved cast to immobilize the knee joint. All subjects exhibited short-latency reflex responses in the soleus muscle. The H/M ratio at midswing was significantly reduced compared with midstance under both UK and RK walking conditions ( P < 0.0001). When compared with UK walking, knee joint angular velocity during RK walking was significantly reduced at midswing ( P < 0.001) and midstance ( P < 0.005) compared with UK. There were, however, no significant differences in H/M ratios at midswing and midstance between UK and RK walking tests. Inhibition of the H-reflex in the soleus muscle during swing was not affected by significant reduction in knee angular velocity. These results indicate that the sensory input from changes in angular velocity at the knee does not lay the inhibitory foundation of phase-related reflex modulation in the ankle extensors during walking as suggested by Brooke and colleagues.

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