Absence Of Movement Research Articles

INTRAUTERINE MYOCARDIAL INFARCTION: UNSUSPECTED DIAGNOSIS IN THE DELIVERY ROOM

We present a case study of intrauterine myocardial infarction. A female neonate suffered from cardiopulmonary arrest at birth. She presented with refractory cardiogenic shock and died. Echocardiogram showed absence of movement of the posterolateral wall of the left chamber. Autopsy showed severe and extensive myocardial necrosis confined by a band of dystrophic calcification that suggested intrauterine origin. The circumflex artery and anterior descending coronary artery both presented with very narrow calibers. Sympathicomimetics administered to the mother also could have played a role in the development of infarction. Myocardial infarction should be suspected if signs of ischemia are present and there is no clear hypoxic-ischemic insult around delivery. Prognosis is poor especially if the main stem of the left coronary is involved. Cardiac transplantation can be considered.

Sensorimotor attenuation by central motor command signals in the absence of movement

Voluntary actions typically produce suppression of afferent sensation from the moving body part. We used transcranial magnetic stimulation to delay the output of motor commands from the motor cortex during voluntary movement. We show attenuation of sensation during this delay, in the absence of movement. We conclude that sensory suppression mainly relies on central signals related to the preparation for movement and that these signals are upstream of primary motor cortex.

158 Is Sighing a Resetting Mechanism of the Autonomic Nervous System?

Sighs are important components of normal breathing. They occur isolated or associated with respîratory pauses. Functional residual capacity and lung compliance increase after sighs. Sighs have been shown to be part of an arousal reaction in infants and to induce heart rate modifications. We investigated the influence of sighs on the autonomic balance in infants.METHODS: 107 sighs (a single breath of at least twice the amplitude of the preceding breaths, not followed by an apnea) from 23 term infants were selected. The selection was made in conditions known not to interfere with spontaneous HR variability (quiet sleep,absence of movements, apnea or false detections of QRS during the 2 preceding and following minutes. Spectral analysis of RR variability was performed on the 2 minutes preceding and the 2 minutes following the sigh. To study the role of the ANS in the development of a sigh, spectral analysis of the period just before the sigh and of the 2 preceding minutes were compared.RESULTS: The 2 minutes following the sigh were characterized by an increased RR interval (p 0.001), an increased total power (p <0.01),an increased LF (p0.01), unchanged HF, increased HF/LF (p <0.001), increased LF normalized (p< 0.001),decreased HF normalized (p<0.001). When comparing the interval sigh minus 4 to 2 minutes with the interval sigh minus 2 to 0 minutes, the opposite evolution of autonomic balance was observed.DISCUSSION: The results of the spectral analysis indicate that sighs are followed by an increase in orthosympatic tone and a decrease in parasympatic tone. On the opposite, the period preceding sighs is caracterized by a decrease in orthosympatic tone and an increase in parasympatic tone.CONCLUSION: These results indicate that sighs could play a resetting role for the autonomic nervous system during quiet sleep in normal infants.

Discharge of identified orexin/hypocretin neurons across the sleep-waking cycle.

Although maintained by multiple arousal systems, wakefulness falters if orexin (hypocretin), orexin receptors, or orexin neurons are deficient; narcolepsy results with hypersomnolence or sudden onset of rapid eye movement sleep [or paradoxical sleep (PS)] and loss of muscle tonus. To learn how orexin neurons maintain wakefulness, we recorded neurons in head-fixed rats across the sleep-waking cycle and then labeled them with Neurobiotin to identify them by immunohistochemistry. We show that identified orexin neurons discharge during active waking, when postural muscle tone is high in association with movement, decrease discharge during quiet waking in absence of movement, and virtually cease firing during sleep, when postural muscle tone is low or absent. During PS, they remain relatively silent in association with postural muscle atonia and most often despite phasic muscular twitches. They increase firing before the end of PS and thereby herald by several seconds the return of waking and muscle tone. The orexin neurons would thus stimulate arousal, while antagonizing sleep and muscle atonia.

Age Comparison Of H-max And M-max Modulation With Different Muscle Length In The Prone Position

It is well known that the amplitude of H-max or any level of H-reflex varies with posture, age, long-term training, physical condition, and/or conditioned stimulation. On the other hand, the amplitude of M-max has been suggested to be neurophysiologically constant, regardless of tested muscle length or any other conditions given, such as prepost training. However, there has been recent debate in the literature concerning the change in M-max during prolonged testing (Crone et al., 1999.) PURPOSE To demonstrate if passive changes in muscle length have differential effects on the soleus H-reflex and soleus M-wave between young and elderly subjects in the prone position. METHODS Fifteen (8 males, 7 females) young active subjects (mean age, 24.7 ± 3.5 years) and 15 (6 males, 9 females) elderly independent subjects (mean age, 70.6 ± 5.1 years) participated in the present study. All subjects read and signed an informed consent form, approved by the university. Soleus H-reflexes were elicited by a 1 ms duration square-wave pulse with the cathode, a 0.9 cm diameter stimulating electrode (Ag-AgCl) placed in the popliteal fossa of the left leg. Subjects were positioned on an isokinetic dynamometer examination table in the prone position with the left foot secured to the footplate and attached to the dynamometer with Velcro straps. The left ankle joint was randomly adjusted to 4 different angles: 10 and 20 deg of dorsiflexion, 10 and 20 deg of plantarflexion and neutral position (0 deg) while the limb was relaxed. 2 × 5 (groups × joint angles) ANOVA model was conducted to examine the difference in each mean peak-to-peak EMG amplitude of the H-max and M-max (mV) and H-max/M-max ratio (%) for each of the groups across the different joint angles. RESULTS Young subjects showed differences in both the H-max and M-max across different muscle lengths (p<0.05). In contrast, elderly subjects demonstrated much less modulation due to muscle length, with only significant differences in the amplitude of H-max at 20 deg of DF (p<0.05). Since no postural balance efforts were required in the prone position, these findings reflect segmental changes only. CONCLUSION This study supports previous investigations in which elderly subjects had less ability to modulate the soleus H-reflex during voluntary activation. The current study supports that elderly also produce less modulation, even in the absence of movement. We conclude that segmental mechanisms, perhaps PI to the Ia terminal regulates these differences.

Age Comparison Of H-max And M-max Modulation With Different Muscle Length In The Prone Position

It is well known that the amplitude of H-max or any level of H-reflex varies with posture, age, long-term training, physical condition, and/or conditioned stimulation. On the other hand, the amplitude of M-max has been suggested to be neurophysiologically constant, regardless of tested muscle length or any other conditions given, such as prepost training. However, there has been recent debate in the literature concerning the change in M-max during prolonged testing (Crone et al., 1999.) PURPOSE To demonstrate if passive changes in muscle length have differential effects on the soleus H-reflex and soleus M-wave between young and elderly subjects in the prone position. METHODS Fifteen (8 males, 7 females) young active subjects (mean age, 24.7 ± 3.5 years) and 15 (6 males, 9 females) elderly independent subjects (mean age, 70.6 ± 5.1 years) participated in the present study. All subjects read and signed an informed consent form, approved by the university. Soleus H-reflexes were elicited by a 1 ms duration square-wave pulse with the cathode, a 0.9 cm diameter stimulating electrode (Ag-AgCl) placed in the popliteal fossa of the left leg. Subjects were positioned on an isokinetic dynamometer examination table in the prone position with the left foot secured to the footplate and attached to the dynamometer with Velcro straps. The left ankle joint was randomly adjusted to 4 different angles: 10 and 20 deg of dorsiflexion, 10 and 20 deg of plantarflexion and neutral position (0 deg) while the limb was relaxed. 2 × 5 (groups × joint angles) ANOVA model was conducted to examine the difference in each mean peak-to-peak EMG amplitude of the H-max and M-max (mV) and H-max/M-max ratio (%) for each of the groups across the different joint angles. RESULTS Young subjects showed differences in both the H-max and M-max across different muscle lengths (p<0.05). In contrast, elderly subjects demonstrated much less modulation due to muscle length, with only significant differences in the amplitude of H-max at 20 deg of DF (p<0.05). Since no postural balance efforts were required in the prone position, these findings reflect segmental changes only. CONCLUSION This study supports previous investigations in which elderly subjects had less ability to modulate the soleus H-reflex during voluntary activation. The current study supports that elderly also produce less modulation, even in the absence of movement. We conclude that segmental mechanisms, perhaps PI to the Ia terminal regulates these differences.

A shared neural network for simple reaction time

Simple reaction time, a simple model of sensory-to-motor behavior, has been extensively investigated and its role in inferring elementary mental organization has been postulated. However, little is known about the neuronal mechanisms underlying it. To elucidate the neuronal substrates, functional magnetic resonance imaging (fMRI) signals were collected during a simple reaction task paradigm using simple cues consisting of different modalities and simple triggered movements executed by different effectors. We hypothesized that a specific neural network that characterizes simple reaction time would be activated irrespective of the input modalities and output effectors. Such a neural network was found in the right posterior superior temporal cortex, right premotor cortex, left ventral premotor cortex, cerebellar vermis, and medial frontal gyrus. The right posterior superior temporal cortex and right premotor cortex were also activated by different modality sensory cues in the absence of movements. The shared neural network may play a role in sensory triggered movements.

FATE OF CEMENTLESS ACETABULAR COMPONENTS RETAINED DURING REVISION TOTAL HIP ARTHROPLASTY

Removal of a well-fixed cementless acetabular component can result in increased operative time and postoperative morbidity. The objectives of this retrospective study were to determine whether retention of a well-fixed acetabular component at the time of isolated femoral revision was compatible with long-term socket survival. The records of eighty-three consecutive patients (ninety hips) in whom a well-fixed cementless socket had been retained during revision of a femoral component were reviewed. The mean age of the patients was 48.7 years at the time of the primary arthroplasty and 54.1 years at the time of femoral revision. The radiographic analysis was based on anteroposterior radiographs and was performed by a single independent reviewer. The intraoperative criterion for stability of the socket was the absence of movement at the bone-implant interface during the application of direct pressure to the edges of the socket in four quadrants with use of a metallic pusher. At the time of the isolated femoral revision, no socket demonstrated a radiolucent line measuring >1 mm in any two zones and forty of the ninety hips had periacetabular osteolysis. The mean size of the osteolytic lesions was 5.71 cm(2) (range, 0.4 to 24.2 cm(2)), and twenty-eight of the forty hips underwent bone-grafting. The mean duration of follow-up was 9.7 years after the isolated femoral revision and 14.9 years after the primary arthroplasty. Five acetabular sockets were revised at a mean of 6.8 years after the femoral revision. Only one of these sockets had failed because of aseptic loosening. With revision of the acetabular component for any reason as the end point, the survival rate was 98.7% at five years and 93.5% at ten years after the femoral revision and 100% at ten years and 93.9% at fifteen years after the primary arthroplasty. No hip showed recurrence or expansion of periacetabular osteolysis. The prevalence of dislocation was 16% (fourteen of ninety). Revision of a stable, cementless acetabular component solely on the basis of its duration in vivo or the presence of periacetabular osteolysis does not appear to be warranted. Retention of the socket with grafting of larger periacetabular osteolytic lesions appears to be consistent with satisfactory socket longevity.

Fetal behavior

Fetal behavior reflects the activity of the fetal central nervous system (CNS). Insight in fetal behavior is crucial for the understanding of normal fetal well-being and in the evaluation of the possibly compromised fetus. In order to recognize ‘behavioral’ patterns, linkage of variables (absence of movements, absence of eye movements, heart rate patterns) is obligatory. No single test can predict with certainty if the fetus is compromised and/or what the optimal timing is for the delivery. That is why the study of fetal behavior is very time-consuming. Development of more appropriate methods to analyze fetal behavior should have high priority in clinical perinatology.

Use of human visual attention cues by olive baboons (Papio anubis) in a competitive task.

The ability of 4 olive baboons (Papio anubis) to use human gaze cues during a competitive food task was investigated. Three baboons used head orientation as a cue, and 1 individual also used eye direction alone. As the baboons did not receive prior training with gestural cues, their performance suggests that the competitive paradigm may be more appropriate for testing nonhuman primates than the standard object-choice paradigm. However, the baboons were insensitive to whether the experimenter could actually perceive the food item, and therefore the use of visual orientation cues may not be indicative of visual perspective-taking abilities. Performance was disrupted by the introduction of a screen and objects to conceal food items and by the absence of movement in cues presented.

Movement Characteristics of Aggregates in Asphalt Mixtures during the Wheel Tracking Test

The deformation characteristics of asphalt mixtures in the crossing direction during the wheel tracking test (1 h, 2500 passes) at high temperature were investigated using dense graded (13F) and drainage asphalt mixture. The two-dimensional movement of the aggregates due to the wheel load was analyzed by right angle photography of the specimen. The behavior of the aggregates was divided into three stages (first, second, and final stage). The aggregates in each mixture moved in the vertical direction under the load, which reflects consolidation of the asphalt mixture. The aggregates moved in the horizontal direction on the surface near the load, which reflects the flow of the asphalt mixture. The aggregates also moved with rotation in both regions. The net result was absence of movement. In addition, the volume change of the asphalt mixture caused by deformation of surface was closely related to the deformation just under the load in the first stage. The asphalt mixture after the wheel tracking test was cut to measure the density. The results showed that the density increased just under the load and decreased in the upper part of the surface near the load.

Chilean Feminism(s) in the 1990s Paradoxes of an Unfinished Transition

This article discusses the changes experienced by the feminist movement in post- transition Chile from the perspective of two specific issues. First, the fundamental "paradox' facing this movement today, that is, its relative success in "gender mainstreaming' together with feminism's increasing weakness as a political actor. And second, the relevance of external and internal factors in transforming feminism and the role each has played in its current situation. The article attempts to answer some of the queries posed by this two-fold process: What explains the feminist movement's absence from public spheres? Why was the movement's previous creative force not translated into renewed political power in the democratic context? What factors have contributed towards the lack of articulation among actors who had been able to form a visible movement for the rest of society in the past? And, to what extent have structural transformations conditioned the changes experienced by feminism? The article is structured in three sections. The first analyses some of the social and political factors relevant for the reconfiguration of the movement in the 1990s through an analysis of the political system. The second concentrates on the object of study itself, that is, the feminist movement. It seeks to reconstruct its trajectory, origins and development, the changes it has undergone throughout the transition process and, especially, its present characteristics. Finally, some concluding remarks are provided.

Time series analysis of leg movements during freezing of gait in Parkinson's disease: akinesia, rhyme or reason?

We quantitatively characterized the fluctuations in the forces under the feet during freezing of gait (FOG) in 11 patients with advanced Parkinson's disease. FOG, a leading cause of falls and impaired functional independence, is a poorly understood debilitating phenomenon that is common among persons with advanced Parkinson's disease. During freezing, the feet are “glued” to the ground and the subject is unable to move forward despite effort in what has been described as an absence of movement. Using time series and fractal analysis methods, we found that FOG is not a frozen akinetic state, nor is freezing random, uncorrelated attempts at overcoming motor blockade. Instead, the forces under the feet oscillate in a fairly organized pattern. However, in contrast to walking and resting leg tremor, the spectrum was broadband and more complex. This complex movement pattern may reflect the activation of multiple networks during FOG.

Modelling succession from pasture to forest in time and space

A set of coupled logistic growth equations is used to simulate the temporal replacement of vegetation (species or groups). Simulation results approximately reproduce two time series of 415 to 585 years obtained from field investigations in the Swiss National Park (SNP). Although the shape and the fit of the simulated curves are convincing, the assumption that all species must be present at the beginning of the simulation and also the absence of movement in space are not realistic. To overcome this, the model is extended to include space and is used for simulating the succession in an abandoned pasture of the SNP. As long as only vegetation change in all individual quadrats is simulated separately, vegetation boundaries remain unchanged over the simulated period of 400 years. When species are allowed to move between quadrats, the spatial pattern changes over the simulated time, and field data can be taken as boundary conditions to realistically simulate change. It is concluded that spatial dynamics must be taken into account to model long-term succession.

Effect of spinal disease on successful arthrodesis in lumbar pedicle screw fixation

Pedicle screw fixation with transverse process fusion has gained widespread acceptance since its inception. Improved rates of arthrodesis have been demonstrated when this technique is used. The authors present one of the largest series of patients to undergo this procedure at a single center; one of the goals was to correlate construct length and spinal disease with rates of successful arthrodesis by conducting a prospective analysis of lumbar fusion in which pedicle screws were placed. During a 7-year period, the senior author performed pedicle screw fixation with posterolateral fusion in 457 patients; the mean follow-up period was 28.4 months. Indications for fusion included metastatic tumor, single-level degenerative disc disease (DDD), trauma, degenerative scoliosis, and translational vertebral instability. Successful fusion was based on the radiographic demonstration of a bilateral contiguous osseous bridge over the transverse processes and absence of movement on dynamic x-ray films. Fusion rates were lowest in cases of tumors (54%) and highest in cases of trauma (96%). In patients with single-level DDD the rate was 91%, and in those with translational instability it was 89%. Fusion rates, however, declined steeply in relation to each additional motion segment in the translational instability group. In this group a strong linear trend for proportion was demonstrated (p < 0.001). The overall fusion rate in patients with degenerative scoliosis was 70%. The overall fusion rate for the entire group was 86%. The data in this study can be used as a benchmark with which to compare newer technologies. Although overall pedicle screw-assisted fusion rate in cases of trauma or selected degenerative lesions approached 90%, the arthrodesis rates are not uniform for the different diagnoses. This appears to be related to the underlying spinal disease and the number of segments included in the fusion.

In vivo genetics of anaesthetic action

In vivo genetics of anaesthetic action

Rapid distributed fronto-parieto-occipital processing stages during working memory in humans.

Cortical potentials were recorded from implanted electrodes during a difficult working memory task requiring rapid storage, modification and retrieval of multiple memoranda. Synchronous event-related potentials were generated in distributed occipital, parietal, Rolandic and prefrontal sites beginning approximately 130 ms after stimulus onset and continuing for >500 ms. Coherent phase-locked, event-related oscillations supported interaction between these dorsal stream structures throughout the task period. The Rolandic structures generated early as well as sustained potentials to sensory stimuli in the absence of movement. Activation peaks and phase lags between synaptic populations suggested that perceptual processing occurred exclusively in the visual association cortex from approximately 90 to 130 ms, with its results projected to fronto-parietal areas for interpretation from approximately 130 to 280 ms. The direction of interaction then appeared to reverse from approximately 300 to 400 ms, consistent with mental arithmetic being performed by fronto-parietal areas operating upon a visual scratch pad in the dorsolateral occipital cortex. A second reversal, from approximately 420 to 600 ms, may have represented an updating of memoranda stored in fronto-parietal sites. Lateralized perisylvian oscillations suggested an articulatory loop. Anterior cingulate activity was evoked by feedback signals indicating errors. These results indicate how a fronto-centro-parietal 'central executive' might interact with an occipital visual scratch pad, perisylvian articulatory loop and limbic monitor to implement the sequential stages of a complex mental operation.

Embryonic assembly of a central pattern generator without sensory input.

Locomotion depends on the integration of sensory information with the activity of central circuitry, which generates patterned discharges in motor nerves to appropriate muscles. Isolated central networks generate fictive locomotor rhythms (recorded in the absence of movement), indicating that the fundamental pattern of motor output depends on the intrinsic connectivity and electrical properties of these central circuits. Sensory inputs are required to modify the pattern of motor activity in response to the actual circumstances of real movement. A central issue for our understanding of how locomotor circuits are specified and assembled is the extent to which sensory inputs are required as such systems develop. Here we describe the effects of eliminating sensory function and structure on the development of the peristaltic motor pattern of Drosophila embryos and larvae. We infer that the circuitry for peristaltic crawling develops in the complete absence of sensory input; however, the integration of this circuitry into actual patterns of locomotion requires additional information from the sensory system. In the absence of sensory inputs, the polarity of movement is deranged, and backward peristaltic waves predominate at the expense of forward peristalsis.

Anterior Cervical Plating Enhances Arthrodesis after Discectomy and Fusion with Cortical Allograft

OBJECTIVE Anterior plate fixation has gained widespread acceptance for the treatment of cervical spondylosis, theoretically enhancing the rate of arthrodesis. There are few studies comparing fusion rates after anterior cervical discectomy and fusion (ACDF) with and without a plate. The purpose of this study was to evaluate the efficacy of anterior cervical plating for fusion enhancement after one- and two-level ACDF with cortical allograft. METHODS A retrospective review was performed with 251 patients who underwent one- or two-level ACDF with cortical allograft and plate stabilization between 1993 and 1999. An independent surgeon reviewer determined fusion status and complications. A successful fusion was defined by the absence of lucency around the graft, evidence of bridging bone between the endplate and the graft, and the absence of movement on dynamic imaging scans. Follow-up data, ranging from 9 months to 3.6 years, were available for 233 patients. A control group of 289 patients who underwent ACDF without plating was described in a previously published report by the senior author (RWH). Therefore, a total of 540 patients were evaluated for determination of the efficacy of anterior cervical plating with cortical allograft bone. Statistical significance was determined by χ2 test. RESULTS The fusion rates for one- and two-level ACDF with anterior fixation were 96 and 91%, respectively, compared with 90 and 72% for one- and two-level ACDF without anterior fixation. The observed increases in fusion rates for both one- and two-level procedures proved to be statistically significant (P < 0.05). There were no recorded infectious, neurological, or graft-related complications among the cohort treated with anterior cervical plating. Compared with the results for the cohort treated without anterior cervical plates, there was a statistically significant decrease in the graft-related complication rate with the application of plates (P < 0.001). Two patients who received plates were noted to have adjacent-segment degenerative changes that required surgical intervention. No hardware fractures were noted; however, one patient was noted to have a single displaced screw, without clinical consequences. CONCLUSION The use of anterior cervical plating after one- and two-level ACDF with allograft cortical bone significantly enhanced arthrodesis. The improved fusion rate and negligible complication rate associated with anterior cervical plating are compelling factors justifying its use in the treatment of cervical spondylosis.

Encefalopatía neonatal grave, secundaria a episodio vasovagal prolongado en una gestante de 31 semanas

Introduction. Vasovagal syncope is not frequent during the second half of pregnancy, although the supine hypotension syndrome is common during this period. During these episodes, the marked hypotension may impede uteroplacental blood flow. Case report. A woman who was 31.5 weeks pregnant lost consciousness for 15 minutes on standing up. 24 hours later, when it was observed that foetal movementhad diminished, a cardiotocographic recording was done. This showed a pathological pattern and foetal biophysical profile on echography showed a marked foetal hypotonia and absence of movement. Emergency caesarean section was carried out and a male foetus delivered, weighing 1.810g, with an Apgar score of 5/6 and requiring intubation and mechanical ventilation for respiratory difficulties and generalized hyptonia with absent reflexes. During the following days he developed generalized hypertonia and died aged 18 days. At necropsy there was severe brain damage, ofischaemic type. Complementary tests on the mother were normal. Conclusions. Severe prenatalencephalopathy secondary to maternal vasovagal syncope is uncommon, and we have found no report of it in the literature. The prolonged duration of the hypotensive episode, together with prematurity, which implies poor regulation of cerebral bloodflow, may have contributed to the severe damage to the central nervous system.