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Biomedical subjects

B Bussel

Publications and source records attributed to B Bussel.

At least 55 records · Page 3Linked to original sources
PubMed1990

Effects of flexor reflex afferent stimulation on the soleus H reflex in patients with a complete spinal cord lesion: evidence for presynaptic inhibition of Ia transmission.

The effects of electrically stimulating the Flexor Reflex Afferent (FRA) on the soleus H reflexes were investigated in 34 paraplegic patients having a clinically complete spinal cord lesion. Conditioning stimuli (5-50 mA) were applied to the ipsilateral or contralateral sural nerve. The conditioning-test interval ranged from 20 to 1000 ms. A late ipsilateral flexor reflex (EMG) was found in all patients. A late contralateral extension reflex was sporadically observed in only 3 patients. The excitability curves usually showed two phases of ipsilateral H reflex inhibition and contralateral H reflex facilitation, one between 50 and 130 ms and the other after over 200 ms. These intervals correspond to early and late flexion reflexes. With high intensity stimulation the early and late ipsilateral inhibition fused. An early low threshold ipsilateral facilitation occurred in 9 patients. The contralateral late facilitation was followed by prolonged inhibition in 10 patients. Changes in presynaptic inhibition were assessed by measuring the heteronymous monosynaptic Ia facilitation from quadriceps to soleus. For methodological reasons, it was only possible to investigate the effect of contralateral conditioning volleys which was performed in 5 patients. A significant and regular reduction of the heteronymous Ia facilitation was found in 4 patients. The reduction is taken to indicate that the FRA evokes presynaptic inhibition of Ia transmission to alpha motoneurones. Presynaptic inhibition was also indicated by the enhancement of a vibratory stimulus induced inhibition in 2 subjects. These results are consistent with the hypothesis that the reflex organization in patients with a spinal cord section is similar to that of the acute spinal cat injected with DOPA.

Adolescent↗
PubMed1989

Late flexion reflex in paraplegic patients. Evidence for a spinal stepping generator.

We demonstrated previously that electrical stimulation of the Flexor Reflex Afferents (FRA) induces a late flexion reflex with a central conduction time longer than 100 msec. Its latency is prolonged by increasing the intensity or the duration of the stimulation. This late reflex is therefore similar to the late flexion reflex observed in acute spinal cat with DOPA. Some findings suggest that in man the late flexion reflex could be inhibited at a premotoneuronal level by contralateral FRA stimulation. In relation to the late flexion reflex, a late contralateral facilitation of soleus monosynaptic reflex (MSR) was observed. Rhythmical activity was observed in only one patient who had an exceptional form of spinal myoclonus. This myoclonus could be modulated by FRA stimulation. These facts show that the reflex organization in paraplegic patients is similar to the one described in acute spinal cat with DOPA and therefore suggest that a spinal stepping generator could exist in humans.

Electric Stimulation↗
PubMed1989

Locomotion in rats transplanted with noradrenergic neurons.

It is known that catecholaminergic drugs can induce both locomotion and a late flexion reflex in spinalized animals. We studied spinal reflexes and locomotor activity in five adult spinal rats which had received a suspension of fetal noradrenergic (NA) neurons below the transection and in three control spinal rats. A rhythmical activity similar to the one of locomotion was regularly observed in three of the grafted rats held above a moving belt. In two of them, the step frequency was increased when the velocity of the moving belt was increased. This was not observed in control rats. A late flexion reflex was obtained in grafted rats that displayed locomotor activity, as well as in two controls. In the two rats which exhibited locomotor activity, analysis showed numerous immunoreactivite (against NA) cells and processes with terminals concentrated around the perikarya of motoneurones.

Animals↗
PubMed1989

Electrophysiological study of the Babinski sign in paraplegic patients.

The physiopathology of the Babinski sign was investigated electrophysiologically in patients with spinal cord lesions. The stimuli were delivered via a blunt probe. The force exerted perpendicular to the plantar surface and the forward displacement of the probe were measured. The responses were recorded by surface electromyography of the Extensor Digitorum Longus and Flexor Hallucis Brevis. The latencies of the responses were 160-500 ms. The shortest latencies were observed after strong and fast-increase, moving or static stimuli. The responses to weak, gradual stimulation, appeared at a constant delay after the start of the displacement, equal to the minimum latency. An earlier phasic response was observed after fast-increase stimulations in two subjects. The long latency of the responses is probably due to a long central delay, similar to the late flexion reflex following electrical stimulation.

Adolescent↗
PubMed1988

Myoclonus in a patient with spinal cord transection. Possible involvement of the spinal stepping generator.

A patient with clinically complete cervical spinal cord transection developed rhythmic myoclonic movements of the trunk and lower limbs, demonstrating that, in man, such movements can be generated within the spinal cord itself when deprived of supraspinal control. Electromyographic (EMG) recordings used to define the features of the myoclonus, which had a frequency of 0.3-0.6 Hz, was bilaterally symmetric, and involved extensor muscles. The EMG bursts always appeared in phase in all muscles involved. Peripheral stimulation of flexor reflex afferents (FRA) could induce, slow or interrupt the rhythmic activity. When FRA stimulation induced a flexion reflex, it occurred between extensor EMG bursts and induced alternating flexion-extension activity which could be sustained for several cycles. Soleus and quadriceps monosynaptic reflexes were depressed during the silent period of the rhythmic activity. Several arguments, mainly the great sensitivity of the myoclonus to flexor reflex afferent stimulation, suggest that the myoclonus observed in this patient was due to partial release of a spinal stepping generator.

Adult↗
PubMed1988

Neurological correlations of ejaculation and testicular size in men with a complete spinal cord section.

This study was of 135 patients with a complete spinal cord section suffered from loss of ejaculation. The spinal cord injuries were classified following the upper and the lower limits of the lesion. The volume of the testes of the patients and of 13 normal control subjects were measured. Physostigmine allowed 75 patients to ejaculate and 15 of them procreated. The possibility of ejaculation after physostigmine mainly depended on the integrity of the T12-L2 metamers. The testicular volume was significantly smaller in patients with a lesion including the T12 metamer than in patients with a lesion sparing the T12 metamer. Six patients with a lesion including the T12 metamer had testicular atrophy. This suggests that T12 segment plays a role in testicular function in paraplegic patients.

Adolescent↗
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↗