Search PubMed⌕ Search

Biomedical subjects

M Verrier

Publications and source records attributed to M Verrier.

25 records · Page 2Linked to original sources
PubMed1975

Neurophysiological changes following spinal cord lesions in man.

A study has been made of the neurophysiological changes that follow spinal cord lesions in man. The Achilles tendon reflex (ATR) is used to estimate transmission in the Ia monosynaptic pathway, and the tonic vibration reflex (TVR) to estimate transmission in the Ia polysynaptic pathway to motoneurons. The inhibition of the H reflex by vibration is used as an estimate of presynaptic inhibition of the Ia monosynaptic pathway. Immediately following a complete lesion of the spinal cord presynaptic inhibition of the Ia monosynaptic pathway appears to be greatly increased. This enhanced inihibition may last several months but it eventually declines and in some instances becomes less than normal. Transmission in the Ia polysynaptic pathway is permanently abolished by a complete spinal lesion. A hypothesis is developed from these findings to explain the evolution of some of the clinical features that follow complete spinal lesions in man. Distinct differences are observed when the spinal lesion is incomplete. Transmission in the Ia polysynaptic pathway may be preserved and there may be no increase in presynaptic inhibition. These differences may depend upon the integrity of certain spinal long tracts which cannot be tested clinically.

Achilles Tendon↗
PubMed1975

The effect of diazepam on presynaptic inhibition in patients with complete and incomplete spinal cord lesions.

The effect of diazepam on presynaptic inhibition in man has been examined in 5 patients with complete spinal transections and 7 patients with incomplete lesions. The inhibition of the H reflex by vibration applied to the tendo Achilles was used to assess presynaptic inhibition of the Ia monosynaptic pathway. Diazepam increased this inhibition in the patients with incomplete lesions, but had no significant effect on the inhibition in the patients with complete spinal transections. Evidently diazepam can enhance presynaptic inhibition in man. The effect, however, cannot be demonstrated in patients with longstanding complete spinal lesions possibly because of some alteration in the segmental presynaptic inhibitory mechanism in this group.

Adult↗
PubMed1975

Neurophysiological effects of prolonged cooling of the calf in patients with complete spinal transection.

The neurophysiological effects of prolonged cooling were examined in seven patients with complete spinal lesions. The twitch tension of the soleus muscle, the direct (M-wave) and relfex (H-wave) response to electrical stimulation of the popliteal nerve, the Achilles tendon reflex (ATR) and the degree of inhibition of the H-wave by muscle vibration were recorded before and after a minimum of forty-five minutes cooling of the calf. Changes in the configuration of the M-wave occurred, suggesting that cooling results in slowing of conduction in muscle or motor nerve fibers. Prolongation of the twitch contraction and half relaxation time was observed, implying that the contractile mechanism of the muscle is affected. A significant decrease in the ATR/M ratio was observed, indicating that cooling, in addition, affects the muscle spindle or its connections. No significant alterations in the H/M ratio or in the degree of suppression of the H-wave by vibration were observed.

Achilles Tendon↗
PubMed1975

Studies on the receptor responsible for vibration induced inhibition of monosynaptic reflexes in man.

A further attempt has been made to define the receptor responsible for the inhibition of monosynaptic reflexes by vibration in man. Vibration of the tendo Achillis will produce inhibition of the H reflex even when the muscles of the anterior compartment of the leg are denervated or blocked with local anaesthetic, implying that there are receptors in the posterior compartment capable of producing this effect. However, there is evidence that vibration spreads through the limb. The inhibition is greater when the anterior compartment is innervated indicating that there is a contribution from receptors in this compartment. Stretching the muscles of the posterior compartment alone, or the muscles of the anterior and posterior compartments reciprocally does not influence the inhibition of the monosynaptic reflex by vibration. These observations support the contention that the reduction of the monosynaptic reflex by vibration in man is due to presynaptic inhibition resulting from activation of primary spindle endings.

Adult↗
PubMed1974

Segmental reflex pathways in spinal shock and spinal spasticity in man.

Activity in three segmental pathways was compared in normal subjects, patients with spinal shock, and patients with established spinal spasticity. The Achilles tendon reflex (ATR) was used to estimate transmission in the Ia monosynaptic pathway. Evidence is produced implying that vibration activates motoneurones principally through a polysynaptic pathway. The tonic vibration reflex (TVR) was used to estimate transmission in this Ia polysynaptic pathway. The percentage of the motoneurone pool (M-response) that could be activated by these pathways was used as a measure of transmission. The H reflex (vibration)/H reflex (control) ratio was used as an estimate of the degree of presynaptic inhibition of the Ia monosynaptic pathway. The findings led to the following conclusions. (1) In spinal shock presynaptic inhibition is greater than normal, transmission in the Ia monosynaptic pathway is reduced, and in the Ia polysynaptic pathway virtually abolished. (2) In established spasticity presynaptic inhibition is impaired, transmission in the Ia monosynaptic pathway is increased, but transmission in the Ia polysynaptic pathway never recovers. (3) The failure of presynaptic inhibition associated with spasticity is a gradual process. A hypothesis to explain these findings is proposed.

Achilles Tendon↗