[Impact of an automated dispensing system for medical devices in cardiac surgery department]. / Impact de l'implantation d'armoires sécurisées dédiés aux dispositifs médicaux dans un service de chirurgie cardiaque.

To secure medical devices' management, the implementation of automated dispensing system in surgical service has been realized. The objective of this study was to evaluate security, organizational and economic impact of installing automated dispensing system for medical devices (ASDM). The implementation took place in a cardiac surgery department. Security impact was assessed by comparing traceability rate of implantable medical devices one year before and one year after installation. Questionnaire on nurses' perception and satisfaction completed this survey. Resupplying costs, stocks' evolution and investments for the implementation of ASDM were the subject of cost-benefit study. After one year, traceability rate is excellent (100%). Nursing staffs were satisfied with 87.5% by this new system. The introduction of ASDM allowed a qualitative and quantitative decrease in stocks, with a reduction of 30% for purchased medical devices and 15% for implantable medical devices in deposit-consignment. Cost-benefit analysis shows a rapid return on investment. Real stock decrease (purchased medical devices) is equivalent to 46.6% of investment. Implementation of ASDM allows to secure storage and dispensing of medical devices. This system has also an important economic impact and appreciated by users.

[Acute Guillain-Barré-like polyradiculoneuritis revealing acute systemic lupus erythematosus: two case studies and review of the literature]. / Polyradiculonévrite aiguë de type Guillain-Barré révélant un lupus érythémateux aigu disséminé: étude de deux cas et revue de la littérature.

The involvement of the peripheral nervous system in systemic lupus erythematosus (SLE) is rare and is dominated by distal symmetric axonal polyneuropathy and multiple mononeuropathy. It usually occurs in late course of the disease. Acute polyradiculoneuropathy of Guillain-Barré syndrome type is very rare and can frequently constitute the first symptom of systemic lupus. We report two cases of acute inflammatory demyelinating polyradiculoneuropathy (AIDP) complicated by respiratory failure due to systemic lupus. In the first case, the pure motor AIDP was the first manifestation of the SLE. The outcome under prednisone treatment was dramatically good with regression of clinical deficit and normalisation of nerve conduction within one month and 12 months of treatment respectively. In the second case the AIDP occurred only one week after diagnosis of SLE and corticotherapy. It was a demyelinating sensory-motor neuropathy. Clinical improvement was obtained after two cures of intravenous gammaglobulin (IVIg). The normalisation of nerve conduction was obtained within 8 months. AIDP is a very rare complication of SLE, but it should be searched as an aetiology of Guillain-Barré syndrome associated to systemic clinical symptoms or to blood inflammation. Corticotherapy could be sufficient, but in some cases the addition of IVIg or plasmapheresis might be necessary.

Activity-dependent development of cortical axon terminations in the spinal cord and brain stem.

Corticospinal (CS) axon terminations in several species are widespread early in development but are subsequently refined into a spatially more restricted distribution. We studied the role of neural activity in sensorimotor cortex in shaping postnatal development of CS terminations in cats. We continuously infused muscimol unilaterally into sensorimotor cortex to silence neurons during the postnatal CS refinement period (weeks 3-7). Using anterograde transport of WGA-HRP, we examined the laterality of terminations from the muscimol-infused (i.e., silenced) and active sides in the spinal cord, as well as in the cuneate nucleus and red nucleus. We found that CS terminations from the muscimol-infused cortex were very sparse and limited to the contralateral side, while those from the active cortex maintained an immature bilateral topography. Controls (saline infusion, noninfusion) had dense, predominantly contralateral, CS terminations. There was a substantial decrease in the spinal gray matter area occupied by terminations from the side receiving the blockade and a concomitant increase in the area occupied by ipsilateral terminations from the active cortex. Optical density measurements of HRP reaction product from the active cortex in muscimol-infused animals showed substantial increases over controls in the ratio of ipsilateral to contralateral CS terminations for all laminae examined (IV-V, VI, VII). Our findings suggest that ipsilateral dorsal horn terminations reflect new axon growth during the refinement period because they are not present there earlier in development. Those in the ventral horn are present earlier in development and thus could reflect maintenance of transient terminations. Increased ipsilateral terminations from active cortex were due to recrossing of CS axons in lamina X and not to an increase in labeled CS axons in the ipsilateral white matter. Examination of brain stem terminations suggested that, between postnatal weeks 3 and 7, development of corticocuneate terminations also is activity-dependent but that development of corticorubral terminations is not. Activity-dependent CS development is a plausible mechanism by which early motor experiences could shape the anatomical and functional organization of the motor systems during a critical postnatal period.

Corticoreticular pathways in the cat. I. Projection patterns and collaterization.

This paper summarizes and compares the projection patterns and the receptive fields of cortical neurons in areas 4 and 6 that project to the pontomedullary reticular formation (PMRF). A total of 326 neurons were recorded in area 4 and 129 in area 6 in four awake, unrestrained cats that were chronically implanted with arrays of electrodes in the PMRF and the pyramidal tract (PT). In area 4, 47% of the neurons projected to the caudal PT but not to the PMRF (PTNs); 19% were activated only from the PMRF [corticoreticular neurons (CRNs)], whereas 27% were activated from both the PT and the PMRF (PTN/CRNs). More PTN/CRNs conducted at velocities >20 m/s (82%) than did CRNs (23%). In area 6, only 19% of the neurons were identified as PTNs, 12% were PTN/CRNs and 31% were CRNs; a further 38% could not be activated from either structure. Collateral branches within the PMRF conducted at maximum velocities of 20 m/s (average = 6.5 m/s). No significant differences in the conduction velocities of the collateral branches were found either between fast and slow PTNs or between area 4 and area 6 neurons. A large proportion of neurons in area 4 (85/173, 49%) were activated by passive manipulation of the more distal, contralateral forelimb, with approximately equal numbers being classed as PTNs, PTN/CRNs and CRNs. Most neurons in area 6 for which a receptive field could be found were excited by lightly touching or tapping the face and neck; a receptive field could not be determined for 39% of the area 6 neurons compared with only 5% of those in area 4. Finally, there was evidence that neurons in quite widespread areas of the pericruciate cortex, including both areas 4 and 6 projected onto similar, restricted regions of the PMRF. The fact that the cortical projection from area 4 to the PMRF includes a high percentage of fast PTNs with a receptive field on the distal forelimb is consistent with the view that this projection may serve to integrate movement and the dynamic postural adjustments that accompany them. The fact that the cortical projection from area 6 to the PMRF is primarily from slow PTNs with receptive fields on the face, neck and back is consistent with a role for this cortical area in adjusting the general posture of the animal on which movements are superimposed.

Corticoreticular pathways in the cat. II. Discharge activity of neurons in area 4 during voluntary gait modifications.

We propose that the descending command from area 4 that is responsible, in part, for the change in limb trajectory required to step over an obstacle in one's path also plays a role in triggering the anticipatory postural modifications that accompany this movement. To test this hypothesis, we recorded the discharge characteristics of identified classes of corticofugal neurons in area 4 of the cat. Neurons were identified either as: pryamidal tract neurons (PTNs) if their axon projected to the caudal pyramidal tract (PT) but not to the pontomedullary reticular formation (PMRF); as corticoreticular neurons (CRNs) if their axon projected to the PMRF but not to the PT; and as PTN/CRNs if their axon projected to both structures. Altogether, the discharge properties of 212 corticofugal neurons (109 PTNs, 66 PTN/CRNs, and 37 CRNs) within area 4 were recorded during voluntary gait modifications. Neurons in all three classes showed increases in their discharge frequency during locomotion and included groups that increased their discharge either during the swing phase of the modified step, during the subsequent stance phase, or in the stance phase of the cycle preceding the step over the obstacle. A slightly higher percentage of CRNs (39%) discharged in the stance phase prior to the gait modification than did the PTNs or PTN/CRNs (20% and 17% respectively). In 37 electrode penetrations, we were able to record clusters of 3 or more neurons within 500 micro(m) of each other. In most cases, PTN/CRNs recorded in close proximity to PTNs had similar receptive fields and discharged in a similar, but not identical, manner during the gait modifications. Compared with adjacent PTNs, CRNs normally showed a more variable pattern of activity and frequently discharged earlier in the step cycle than did the PTNs or PTN/CRNs. We interpret the results as providing support for the original hypothesis. We suggest that the collateral branches to the PMRF from corticofugal neurons with axons that continue at least as far as the caudal PT provide a signal that could be used to trigger dynamic postural responses that are appropriately organized and scaled for the movements that are being undertaken. We suggest that the more variable and earlier discharge activity observed in CRNs might be used to modify the postural support on which the movements and the dynamic postural adjustments are superimposed.

Role of the motor cortex in the control of visually triggered gait modifications.

One important aspect of locomotor control is the ability of an animal to make anticipatory gait modifications to avoid obstacles, by stepping either around them or over them. This paper reviews some of the evidence that suggests that the motor cortex is one of the principal structures involved in the control of such anticipatory gait modifications in cats, in particular when they are triggered by a visual signal. Evidence for this statement is provided both from experiments in which the motor cortex has been lesioned or inactivated and from studies in which the activity of motor cortical neurones has been recorded during locomotor tasks in which visual information is required to ensure the correct positioning of the paw or an appropriate modification of the limb trajectory. Inactivation of small regions of the motor cortex with the GABA agonist muscimol results in changes in the limb trajectory so that cats hit an obstacle instead of stepping over it as they do normally. A similar disruption of the hindlimb trajectory is seen following lesions of the spinal cord at T13 that interrupt the corticospinal tract. The results from cell recording studies are complementary in that they show that the activity of many identified pyramidal tract neurones increases when the cat is required to modify the forelimb or hindlimb trajectory to step over obstacles. We suggest that the major function of this increased discharge frequency is to regulate the amplitude, duration, and temporal pattern of muscle activity during the gait modification to ensure an appropriate modification of limb trajectory. We further suggest that different groups of pyramidal tract neurones are involved in regulating the activity of groups of synergistic muscles active at different times in the gait modification. For example, some groups of pyramidal tract neurones would be involved in ensuring the appropriate and sequential activation of the muscle groups involved in the initial flexion of the elbow, while others would be active prior to the repositioning of the paw on the support surface. We discuss the possibility that the motor cortical activity seen during locomotion is the sum result of a feedforward signal, which provides visuospatial information about the environment, and feedback activity, which signals, in part, the state of the interneuronal pattern generating networks in the spinal cord. The way in which the resulting descending command may interact with the basic locomotor rhythm to produce the gait modifications is discussed.

Motor cortical activity during voluntary gait modifications in the cat. II. Cells related to the hindlimbs.

1. To determine whether the motor cortex is involved in the modification of the hindlimb trajectory during voluntary adjustments of the locomotor cycle, we recorded the discharge patterns of 72 identified pyramidal tract neurons (PTNs) within the hindlimb region of pericruciate area 4 during a task in which cats stepped over obstacles attached to a moving treadmill belt. Data were also recorded from representative flexor and extensor muscles of the fore- and hindlimbs contralateral to the recording site. 2. To step over the obstacles, the cats increased flexion sequentially at the knee, ankle, and then the hip to bring the leg above and over the obstacle. This flexion movement was followed by a strong extension of the whole limb that repositioned the foot on the treadmill belt. These changes in limb trajectory were associated with large changes in the level of the activity of many flexor and extensor muscles of the hindlimb, and especially of the knee flexor, semitendinosus. On the basis of the time of onset of the knee and ankle extensor muscles in those steps when the limb was the first to be brought over the obstacle, the swing phase of the modified step cycle was subdivided into two parts, Phase I and Phase II, which correspond respectively to the flexion of the limb (F) and the initial extension (E1). 3. The temporal sequence of the movement was the same whether the hindlimb was the first (lead) or second (trail) to step over the obstacle, although the relative time between flexion at the three joints was changed in the two conditions. 4. Seventy-two PTNs were recorded from the posterior bank of the cruciate sulcus during the voluntary gait modifications. Sixty-three (63/72) of these PTNs had receptive fields that were confined to the contralateral hindlimb, or were recorded from penetrations in which such cells were found. Nine (9/72) PTNs had receptive fields on both the contralateral fore- and hindlimbs. Microstimulation applied through the recording electrode evoked, in all cases, brief twitch responses only in contralateral hindlimb musculature. 5. Forty-two (42/63) of those PTNs with receptive fields confined to the hindlimb showed a significant increase in their discharge frequency when the limb contralateral to the recording site was the first to step over the obstacle (lead limb). Twenty-nine PTNs (29/63) discharged maximally during the swing phase (18 in Phase I and 11 in Phase II), including two PTNS that also increased their discharge frequency during stance.(ABSTRACT TRUNCATED AT 400 WORDS)

Critical timing of sensorimotor cortex lesions for the recovery of motor skills in the developing cat.

Forelimb movements and motor skills were studied in adult cats in order to determine the effect of brain damage inflicted at different postnatal ages. The unilateral lesion included the cortical areas from which the pyramidal tract originates in cat: areas 4 and 6 corresponding to the motor cortex; areas 3, 2 and 1 corresponding to the primary somatosensory cortex; and part of area 2 prae-insularis corresponding to the secondary somatosensory cortex. Forelimb performance of a food-retrieving task requiring proximal as well as distal muscles was assessed by comparing the limb contralateral to the damaged hemisphere (affected limb) with the limb contralateral to the intact hemisphere (non-affected limb) that appeared to perform the task as well as both limbs of control animals. In simple task-related movements, all operated animals were rapidly able to achieve the goal with the affected limb, whatever the age at lesion. In complex tasks, the ability to achieve the goal with the affected limb decreased with increasing age at lesion. Recovery of distal skills, i.e. grasping and wrist rotation, did not occur in animals operated on after the 23rd postnatal day (PND), and recovery of proximal skills, i.e. amplitude and precision of the reaching movement, did not occur in animals operated on after the 45th PND. The critical time for the recovery of distal skills lies somewhere between the 23rd and 30th PND, whereas for the recovery of proximal skills it lies somewhere between the 45th and 60th PND. These critical dates for the recovery of motor skills support the Kennard doctrine. Different critical times for proximal and distal skills may be explained in terms of different stages of sensorimotor development in kitten. It is hypothesised that recovery only occurs if brain damage is inflicted before maturation of the nervous system underlying a given motor skill.

Recovery of distal skills after neonatal lesion of the sensorimotor cortex in the cat.

The cytoarchitectonic cortical areas containing the cells of origin of the pyramidal tract were unilaterally removed from kittens during the first postnatal month. After 5 months, the distal skills of these operated animals were analyzed using a food retrieving task. After an initial deficit, cats achieved the same performance in grasping and wrist movement with the limb contralateral to the lesion as with the opposite limb. The duration of the deficit was dependent on age at the time of lesion. Recovery of distal skills after neonatal lesion is discussed with regard to the low degree of maturity of the corticospinal tract in newborn cat.