Search PubMed⌕ Search

Biomedical subjects

B Bussel

Publications and source records attributed to B Bussel.

At least 55 records · Page 3Linked to original sources
PubMed1995

Fictive motor activities in adult chronic spinal rats transplanted with embryonic brainstem neurons.

The present study was designed to examine the effects of an intraspinal transplantation of embryonic brainstem neurons on fictive motor patterns which can develop in hindlimb nerves of adult chronic spinal rats. Seventeen adult rats were spinalized at T8-9 level and, 8 days later, a suspension of embryonic cells obtained either from the raphe region (RR, n = 8) or from the locus coeruleus (LC, n = 9) was injected caudally (T12-13) to the cord transection. Eight control animals (control rats) were spinalized and injected with vehicle under the same conditions. One to three months later, the animals were decorticated and fictive motor patterns were recorded in representative hindlimb nerves. The data revealed that both control and grafted spinal rats could exhibit two distinctly different fictive motor patterns, one which could be associated with stepping and the other with hindlimb paw shaking. They further showed that following transplantation of embryonic RR or LC neurons the excitability of the spinal stepping generator was increased, whereas that of the spinal neural circuits which generate hindlimb paw shaking was not significantly affected. A histological analysis performed on the spinal cord segments below the transection revealed complete absence of serotonin and noradrenaline immunoreactivity in control spinal animals and, in both types of grafted rats, an extensive monoaminergic reinnervation with synaptic contacts between monoaminergic transplanted neurons and host interneurons and/or motoneurons. The possible mechanisms by which grafted monoaminergic neurons can influence the spinal motor networks are discussed.

Animals↗
PubMed1993

Slowly progressive apraxia: two case studies.

Two patients with a slowly progressive and severe motor apraxia are presented. In one case, there was only apraxia; in the other there was moderate memory disturbance and a mild decline of global intellectual ability, suggesting a more widespread cognitive dysfunction. In this second case, recognition of the correct use of objects was also severely impaired, suggesting a disturbance of motor knowledge. In both cases, apraxia was asymmetrical, and associated with a contralateral atrophy of the upper parietal cortex, suggesting a differential involvement of separate action systems for each hand.

Aged↗
PubMed1993

Trophic effects on testes in paraplegics.

Testicular biopsies and hormone profiles were obtained from 23 paraplegic patients who had sustained a complete spinal cord section. The hormone profiles were normal, but patients with a spinal lesion including the T10-L2 metameres showed a particular pattern of germinal cell abnormalities. The atrophy is multifactorial, but may well include destruction of the sympathetic innervation of the testis by the lesion.

Adolescent↗
PubMed1993

Effect of intrathecal baclofen on the monosynaptic reflex in humans: evidence for a postsynaptic action.

Intrathecal baclofen is a very powerful antispastic agent. Its mechanism of action on the monosynaptic H-reflex in spinal patients was investigated. It could inhibit rapidly and profoundly monosynaptic reflexes in lower limbs, but did not modify Ia vibratory inhibition of the soleus H-reflex. To assess more precisely its effect on Ia afferents, an experimental paradigm using Ia heteronymous facilitation of the soleus H-reflex was used. Intrathecal baclofen did not modify the amount of monosynaptic facilitation of the soleus H-reflex brought about by stimulation of the femoral nerve. This demonstrates that the main part of the inhibitory effect of baclofen on the H-reflex in spinal patients is not due to a presynaptic effect, suggesting a postsynaptic site of action.

Adolescent↗
PubMed1992

Inhibitory effects on flexor reflexes in patients with a complete spinal cord lesion.

The inhibitory effects on flexors of electrical stimulation of a distal peripheral nerve were investigated in 7 paraplegic patients having a complete spinal cord section. The stimuli (3-50 mA) were applied to the sural nerve. Their effects were investigated on: 1) the ipsi- and contralateral H reflex of the Tibialis Anterior (TA); 2) the continuous EMG activity reflexly elicited in TA by a sustained pinch of the foot and 3) on the reflexes evoked in TA by contralateral sural nerve stimulation. Sural nerve stimulation induced two peaks of facilitation of the ipsilateral TA H reflex that could be replaced by inhibition as the stimulus intensity was increased. The comparison of the effect on H reflexes and the EMG activity suggests presynaptic inhibition of Ia fibres at time intervals longer than 300 ms. The stimulation could depress the sustained EMG reflex activity and induce a period of silence whose duration increased with the intensity of the stimulation. As shown in a previous study, a sural nerve stimulation induced a reflex in TA with a prolonged (more than 130 ms) latency. This late reflex could be selectively inhibited by a contralateral sural nerve stimulation, probably at an interneuronal level. These results confirm that the late reflex in TA is similar to the one observed after Flexor Reflex Afferent (FRA) stimulation in the acute spinal cat with DOPA. In addition, they show that at least some part of the "half centre" organization which has been described in the acute spinal cat with DOPA is also present in the human spinal cord chronically deprived of supraspinal control.

Adolescent↗
PubMed1991

Systematic lower limb phlebography in acute spinal cord injury in 147 patients.

This study was concluded on paraplegic and tetraplegic patients of all aetiologies except neoplasic, where paralysis developed within 48 hours. All patients were admitted to the rehabilitation department within 90 days after the onset of paralysis. In a preliminary review of 328 files, there were 27 cases of clinical deep vein thrombosis (DVT) and 10 with pulmonary embolism (PE), 6 of which were fatal. A prospective study was conducted, based on systematic detection of asymptomatic DVT with phlebography. Among the 147 patients, 20 previously presented with DVT. The 127 others underwent phlebography which showed 39 DVT in 29 patients. Eighty seven patients with negative phlebography underwent a second study a month later which showed 14 DVT in 12 patients. Only one minor pulmonary embolism occurred in these 147 patients. The incidence of DVT after acute spinal cord injury and the frequent absence of clinical manifestations were confirmed. Prophylactic anticoagulant therapy is useful but insufficient. This study demonstrates that systematic and repeated detection of DVT by phlebography may reduce the incidence of PE.

Adult↗
PubMed1990

Influence of plantar cutaneous afferents on early compensatory reactions to forward fall.

The influence of cutaneous afferents in the compensatory reactions to a forward fall was investigated. Modification of cutaneous afferent activity was obtained in two different ways: first, by varying the initial pedal support conditions, secondly by anesthetizing the plantar foot sole. The initial pedal support conditions were: 1) bipedal posture, 2) unipedal posture, with contact and 3) unipedal posture, without contact. Nine healthy subjects participated in the control (without anesthesia) experimental session, of which three subjects participated in a session where the plantar sole was anesthetized. The compensatory reactions to a perturbation of balance of a subject initially with a bipedal stance, showed synchronized EMG activity in both Soleus muscles, starting on average at 59 ms, and a burst of EMG activity in the Tibialis Anterior of the starting foot after 200 ms. When the subject was in unipedal posture, the EMG responses on the side which was without support, showed several modifications: the EMG burst in Soleus was strikingly depressed, the response in Tibialis Anterior appeared earlier (mean latency 90 ms) and its magnitude was enhanced. When this foot was in contact with a rigid support, the Soleus showed a short burst of activity and the activity in Tibialis Anterior started at a mean latency of 150 ms.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
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↗