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Biomedical subjects

B Bussel

Publications and source records attributed to B Bussel.

At least 73 records · Page 4Linked to original sources
PubMed1987

Long-latency spinal reflex in man after flexor reflex afferent stimulation.

Electromyographic (EMG) flexor muscle responses evoked by electrical stimulation of ipsilateral peripheral nerves were studied in 16 patients with clinically complete spinal cord transection. Stimuli were applied either to a cutaneous nerve (sural) or to a mixed nerve (tibial) and muscle responses were recorded from tibialis anterior, biceps femoris and rectus femoris. EMG recordings after both sural and tibial nerve stimulation showed that distinct early and late ipsilateral flexor muscle responses could be elicited. This distinction was more evident for tibialis anterior. The latency of the early responses averaged approximately 100 ms with sural and 75 ms with tibial nerve stimulation. This corresponds to the latency of the flexion withdrawal reflex previously described in normal man. After sural stimulation, the early reflex appeared in biceps femoris at a threshold intensity not significantly different from that in normal man given the same stimulation parameters. Late responses appeared after a longer latency (130 ms) and at a lower threshold than the early flexor reflex. In all patients a striking feature of the late response was that its latency increased with increasing stimulus intensity, the maximum latency being as long as 450 ms. This increase also occurred with increasing duration of high intensity stimulus trains. Neither the appearance of a late response nor its latency increase could be explained by a peripheral loop due to a preceding muscle contraction (from either motor axon stimulation or motoneuronal discharge corresponding to the early flexion reflex). It was therefore concluded that both were directly elicited by the afferent volley set up by electrical stimulation. The low threshold of the late reflex corresponded to the excitation of relatively rapidly conducting afferents and its central spinal delay was more than 100 ms. The late reflexes were compared with those described by Andén et al. (1964) in the acute spinal cat injected with DOPA and were found to have similar characteristics. The mechanism for the increase in latency of the late response is discussed in relation to the interpretation of Lundberg (1979).

Adolescent↗
PubMed1987

An electrophysiological investigation into the pain-relieving effects of heterotopic nociceptive stimuli. Probable involvement of a supraspinal loop.

It has previously been shown that, in normal subjects, heterotopic painful stimuli induce parallel decreases in the sensation of pain and the nociceptive spinal flexion reflex RIII simultaneously evoked by electrical stimulation of the sural nerve. By contrast, heterotopic non-noxious stimuli were ineffective in this respect. In order to assess the possible involvement of supraspinal structures in these changes, we have now compared the effects of nociceptive electrical stimuli applied to the fourth and fifth fingers of the hand on the contralateral RIII reflex in 5 normal subjects and 5 tetraplegic patients suffering from a clinically complete spinal cord transection of traumatic origin. The tetraplegic patient had a C5, C6 or C7 spinal cord transection with lower segments, notably C8 and T1, clinically uninjured. In these patients, sural nerve stimulation induced a biceps femoris reflex which did not differ from the RIII reflex recorded in normal subjects, either in terms of latency or of threshold. In both groups, the RIII reflex threshold was determined and a juxta-threshold RIII reflex was studied before, during and after a 2 min period of conditioning stimulation. The conditioning procedure consisted of nociceptive electrical stimulation applied to the digital branches of the ulnar nerve which arises from C8 and T1, i.e., below the level of the patients' spinal transection. In normal subjects such conditioning elicited painful sensations of 'pin prick', 'burning' and 'squeezing'. It simultaneously induced a strong inhibition of the RIII reflex which outlasted the conditioning period by several minutes. By contrast, non-nociceptive electrical conditioning stimuli (0.1 ms duration pulses of 6 to 8 mA intensity, at 3/s), similarly applied to the digital branches of the ulnar nerve were totally ineffective. In tetraplegic patients not only was the RIII reflex never decreased by the heterotopic nociceptive stimulation but it was, in fact, slightly enhanced. These results show that the effects of heterotopic nociceptive stimulation observed in normal man are possibly mediated by a complex loop involving supraspinal structures. This further underlines the similarity between this phenomenon and the Diffuse Noxious Inhibitory Controls (DNIC) described in the rat, since the latter are observed in intact but not in spinal animals. These findings are discussed with reference to counter-irritation phenomena and procedures aimed at producing analgesia by somatic electrical stimulation.

Adult↗
PubMed1985

[Cerebral aspergilloma. X-ray computed tomographic aspect. Apropos of a case. Review of the literature].

Cerebral aspergilloma of initial sinus origin developed in a patient with mixed cell leukemia. Computed tomography imaging showed signs of a cystic multitumoral syndrome with a crown-shaped filling image without peritumoral edema. Follow up of cerebral lesions during medical treatment was by repeated CT scans, with progressive regression of images over a period of 8 months. The patient died after recurrence. Aspergilloma is seen mainly in patients with alternating immunity defenses.

Aspergillosis↗
PubMed1985

[Close interdependence between passive and active soleus muscle torques in man: approach to the coregulation of the number of sarcomeres and length of the connective tissue].

Soleus muscle has, to as great an extent as possible, been functionally isolated in man. A device previously described permitted measurement of the soleus torque as a function of the tibia-calcaneum angle, and not as a function of tibia-foot angle. This latter angle cannot be correctly related to soleus length, since the arch of the foot can not be considered as rigid throughout the experiment. Ankle movements were performed on a horizontal plane by successive increments of 5 degrees from full extension (plantar flexion) up to full flexion (dorsiflexion). Passive torques were measured for every angle. At the same angles, the total torques were recorded while the subject exerted a voluntary constant contraction which corresponded to 45% of the maximum integrated electromyographical activity of soleus muscle. The active torque-angle curve was obtained by subtracting, for the same angle, the passive from the total torques. It must be stressed that, when the muscle is maximally shortened, little or no torque was measured. For the angle corresponding to the top of the sub-maximal active curve (integrated electromyographic activity 45% of the maximum), the passive torque was about 1.75 Nm and showed no significant interindividual variations. This result contrasted with the marked interindividual shifts which affect both passive and active curves. This interdependence of passive and active curves in human soleus muscle is compatible with the results of a previous study in the cat showing the concomitant adaptations of sarcomere number and connective tissue length.

Calcaneus↗
PubMed1984

[Calcified herniated disk at the dorsal level].

Computed tomography examinations were conducted in two cases of calcified thoracic vertebral disc hernias. The physiopathology, polymorphic clinical features, radiological appearances (including CT scans) and treatment are discussed.

Adult↗
PubMed1983

Effect of a synthetic enkephalin analogue on spinal nociceptive messages in humans.

The effects of a single dose (1.0 mg. i.v.) of a synthetic methionine enkephalin, FK 33-824 (FK) on spinal nociceptive pathways were studied in 3 normal subjects and in 3 paraplegic patients. In normal patients, FK 33-824 produced an increased threshold of a nociceptive flexor reflex of the lower limb as well as a decrease in the slope of the recruitment curve of this reflex as a function of stimulus intensity. The inhibition of a monosynaptic reflex induced by conditioning noxious cutaneous stimulation was also reduced by FK 33-824. In patients, administration of FK 33-824 resulted in marked depression of supraliminal nociceptive reflexes, showing a direct spinal effect of this opioid. In all subjects, FK 33-824 also produced severe side effects. All these effects were naloxone-reversible (0.03 mg/kg. i.v.). The clinical implications of these data are discussed.

Adult↗
PubMed1983

Aortic occlusion by a balloon catheter: a method to induce hind limb rigidity in rats.

Post-ischaemic spinal extensor or flexor rigidity can be induced in different species by clamping or ligature of the descending aorta after thoracotomy or laparotomy. A similar motor deficit can also be induced by an intraluminal aortic occlusion produced by inflation of a balloon attached to the tip of a catheter inserted via the femoral artery. This method is easy to perform and avoids all the possible complications of thoracotomy or laparotomy. In rats the occlusion time for obtaining the maximum percentage of animals exhibiting a permanent hind limb extensor (62.5%) or flexor (12.5%) rigidity was 15-16 minutes. A marked depression of hind limb sensory perception accompanied this rigidity but there were no urinary, bowel or skin disturbances. The unilateral femoral ligation following the catheterization did not induce a difference in muscle tone between both hind limbs. The present procedure which is simpler than other published procedures might thus serve as a useful animal model for spastic paraplegia.

Animals↗
PubMed1981

Morphine reinforces post-discharge inhibition of alpha-motoneurons in man.

Morphine chlorhydrate (0.25 mg/kg)produced a significant and constant reinforcement of post-discharge inhibition of alpha-motoneurons in both normal and paraplegic humans. This effect was reversed by naloxone hydrochloride (0.02 mg/kg). These data do not allow to differentiate the effects of morphine on recurrent inhibition and on A.H.P.

Adult↗
PubMed1978

Mechanism of monosynaptic reflex reinforcement during Jendrassik manoeuvre in man.

The facilitating effect of the Jendrassik manoeuvre on monosynaptic reflexes in man has been studied by comparing H and T reflexes of the soleus and by blocking the effects of spindle activation by ischaemia of the leg. The Jendrassik manoeuvre equally enhances H and T reflexes provided that the test reflexes are small. The H reflex remains facilitated when the spindle activation cannot affect the soleus alpha-motoneurones--that is, when the Ia afferent nerve fibres from the soleus are blocked by ischaemia. It is concluded that the facilitating effect of the Jendrassik manoeuvre on the alpha-motoneurones is not predominantly routed via the gamma-loop.

Achilles Tendon↗
PubMed1978

[Change in recurrent inhibition when standing in normal subjects and spastics (author's transl)].

In normal subjects and patients with diseases of the upper motor neurone, recurrent inhibition directed to soleus motoneurones was studied in three different postures: sitting (control situation), standing when leaning backward on a wall, standing independently without the support of a wall. In normal subjects, this recurrent inhibition was not modified when standing with the support of a wall, while it was enhanced when standing without such a support.

H-Reflex↗
PubMed1978

[Peripheral and central factors controlling reciprocal Ia inhibition in man].

Variations of the soleus H reflex were studied during voluntary contractions of the tibialis anterior in man. At the onset of contraction there was a weak inhibition of the soleus H-reflex which was not related to the force of the tibialis anterior contraction. 110 msec after the onset of the EMG activity the inhibition became secondarily more marked and was then related to the force of the contraction. This secondary potentation of the H-reflex inhibition is brought about by group I fibres activity, since it was markedly reduced during ischemia of the leg. It is concluded that the early inhibition is only due to suprasegmental activity whereas during the secondary part of the inhibition, there is a supplementary inhibitory action likely brought about by Ia fibres tibialis anterior. The secondary potentiation of the inhibition is therefore likely to be produced via the gamma loop.

Central Nervous System↗
PubMed1977

Influence of voluntary movement and posture on recurrent inhibition in human subjects.

Recurrent inhibition elicited by a conditioning H reflex is measured in normal man by the amount of inhibition of a test H reflex produced by motoneurones that have already given rise to the conditioning reflex. The recurrent inhibition of soleus motoneurones is lowered during a voluntary contraction of this muscle while it is enhanced during a voluntary contraction of its antagonist, the tibialis anterior, and not modified during a contraction of the quadriceps. This recurrent inhibition is also enhanced when the subject is standing without support. These changes in recurrent inhibition are thought to imply supraspinal mechanisms acting on Renshaw cells. The functional significance of these changes is discussed in relation to the recent finding in animals of recurrent depression of the transmission in the Ia inhibitory pathway.

Adult↗
PubMed1977

Inhibition of human motoneurons, probably of Renshaw origin, elicited by an orthodromic motor discharge.

1. The pattern of variations of a test H-reflex after a conditioning H-reflex was investigated in human subjects by an experimental design in which both reflexes involved the same soleus motoneurones. This was made possible by using a method based upon a collision in the motor axons between the orthodromic conditioning reflex volley and the antidromic volley elicited by a test stimulus supramaximal for the motor axons.2. The variations of the test reflex amplitude seen when increasing the conditioning reflex discharge were studied. This was made possible by facilitating the conditioning reflex without changing the strength of the afferent volley. This facilitation was obtained through a soleus stretch elicited by a stimulation of the plantar nerves.3. The amplitude of the test reflex depended only on the size of the conditioning reflex discharge.4. As long as the conditioning reflex was of low amplitude, all the motoneurones responsible for the conditioning response could be activated by the test volley, even though these motoneurones were undergoing after-hyperpolarization. This indicates that, in man, the after-hyperpolarization of the most excitable motoneurones can be completely overcome by a large Ia afferent volley.5. Increasing the conditioning reflex beyond a specific value resulted in an absolute decrease in the number of motoneurones involved in the test reflex. The amount of this decrease was related only to the amplitude of the conditioning reflex.6. This inhibition decreased progressively as the time interval separating the test stimulus from the conditioning stimulus increased. The time course of this inhibition was studied with conditioning reflexes of different amplitudes. The duration of the inhibition increased with the size of the conditioning reflex.7. These results strongly suggest that Renshaw cells excited by the conditioning reflex are responsible for this inhibition. The results are in agreement with observations made in animals on recurrent inhibition.

Adult↗
PubMed1976

[Paralysis following Dimer X radiculography].

The authors report four cases of cauda equina syndrome following Dimer X radiculography. The cases are described and commented upon. The conclusion is that Dimer X is a substrate associated with a certain degree of toxicity. Indications for and technique in sacroradiculography should be rigorous.

Adult↗