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PubMedDate not supplied

Electromyographic study of newborn stepping in neonates and young infants.

The purpose of this study was to examine the developmental changes in the functional mechanisms of leg muscles in newborn stepping over the first four months in ten normal neonates. Neonatal stepping in the first month showed excessive coactivation, that is, co-contraction patterns of mutual antagonists appeared especially during stance phase. The discharge patterns of co-contraction in neonatal stepping began to change to reciprocal patterns in young infant stepping (after the first month), but excessive muscular activities associated with a slightly squatted posture and forward lean still remained. Strong muscle activities of leg extensors due to a parachute reaction of the legs before floor contact, not seen in the neonatal period, began to appear in the young infant period from one month of age to three months. We suggest that these gradual changes of leg muscular activity in newborn stepping are evoked by development of balance, postural control, and strength, thereby modulating the neonatal stepping reflex.

Child Development↗
PubMed1998

A preliminary study on delayed vestibulo-cerebellar effects of Tokyo Subway Sarin Poisoning in relation to gender difference: frequency analysis of postural sway.

To evaluate delayed (long-term) effects of acute sarin poisoning on postural balance, nine male and nine female victims of the Tokyo Subway Sarin Poisoning in Japan (sarin cases) were examined by computerized posturography 6-8 months after the poisoning. Their plasma cholinesterase activities (ChE) on the day of the poisoning (March 20, 1995) were 13-95 (mean 68.2) IU/l for females and 19-131 (mean 75.9) IU/l for males, which were not significantly different between the two sexes. In females, the postural sway of low frequency (0-1 Hz) in the anterior-posterior direction and area of sway with eyes open was significantly larger in the cases than in the controls. Romberg quotients for the low-frequency sway in the anterior-posterior direction for females and low-frequency sway and length of sway in the medio-lateral direction for males were significantly related to log ChE. It is suggested that a delayed effect on the vestibulo-cerebellar system was induced by acute sarin poisoning; females might be more sensitive than males.

Adult↗
PubMed2001

Phylogenetically conditioned possibilities of the realization and of the development of complex movements at the age of 7 years.

Upon entering a school the seven-year olds (+/- 2 months) underwent a systematic, experimental, specially programmed, eighteen-month-long transformational procedure. The objective of the procedure was to develop the abilities and to observe the growth and the development of children, both girls and boys. The data were processed by means of discriminant analyses in each of the three control points. There was a total sample of 487 children. With regard to the phylogenetic characteristics of a human, it may be said that the basic abilities connected with phylogenetic development may be clearly recognized, precisely in such a way that children replicate this development throughout their earliest childhood. Most probably, the basic ability was the ability to maintain a postural balance, followed by the ability of movement control. Then came object manipulation by upper extremities, followed by the significance of resistance to inertial forces while moving, and ultimately the control of complex movements of the whole body.

Child↗
PubMed1985

Spatial orientation mechanisms and their implications for falls.

Postural stability is only one function on a multisensory system that also subserves spatial orientation and gaze stability. The problem of falling is discussed in the context of understanding the nature and integration of these sensory loops, and the possibility of their modification is discussed. The characteristics of the visual system contributing to spatial orientation are analyzed. The role of gaze stability in postural balance and its modification as a function of age are also discussed. It is suggested that our understanding of the problem of falling will be enhanced by a research strategy that views the problem as a special case of spatial orientation.

Accidents↗
PubMed1991

Effect of work load and respirator wear on postural stability, heart rate, and perceived exertion.

The effects on postural stability (sway) were investigated for different work loads under conditions of wearing a full facepiece respirator and not wearing any respiratory protection device. Fifteen subjects accomplished light (40 W), moderate (85 W), and heavy (125 W) work loads under the two conditions. Measurements of postural sway were made immediately after each load by using a multicomponent, strain gage-type force platform. Changes in each subject's movement pattern of the center of pressure were quantitated and compared to their initial baseline sway tests. Each subject's heart rate and perceived exertion were also recorded during each condition. A statistically significant effect (p = 0.007) caused by work load was observed for total length of sway with or without a respirator. An interaction approaching statistical significance (p = 0.056) between work load and respirator use was found. This indicated that sway increased more quickly and in a more consistently linear fashion with increasing work load under the respirator condition (p = 0.02) compared to the nonrespirator condition. The results from the respirator condition showed linear increases in postural sway length across the entire range of work loads, but sway length in the nonrespirator condition showed an increase only at 125-W work loads. The greater increase in sway during the postural balance test could be attributable to the increasing work load-induced proprioceptive fatigue effect on the nervous system's ability to process signals from proprioception systems incongruent with body sway. The heart rate was significantly higher during respirator wear (an increase in heart rate averaging 5.62 beats/min).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1997

Postural sway frequency analysis in workers exposed to n-hexane, xylene, and toluene: assessment of subclinical cerebellar dysfunction.

To clarify the effects of organic solvents on the postural balance system, 29 male sandal, shoe, and leather factory workers exposed to n-hexane, xylene, and toluene (solvent workers) were examined by computerized static posturography with sway frequency analysis. Concentrations of metabolites of solvents in urine samples taken from the workers in the morning before work ranged from 0.41 to 3.06 (mean, 1.20) mg/g creatinine (Cn) for 2,5-hexanedione, from 0.10 to 0.43 (mean, 0.19) g/g Cn for methylhippuric acid, and from 0.05 to 2.53 (mean, 0.37) g/g Cn for hippuric acid; estimated concentrations of n-hexane in workplace air ranged from 13 to 100 (mean, 40) ppm. Control subjects were 22 healthy males without exposure to solvents. With eyes open, postural sway with a frequency of 2-4 Hz in solvent workers was significantly larger than that in controls in the anteroposterior direction. With eyes closed, sway with a frequency of 0-1 Hz was significantly larger in solvent workers in the mediolateral and anteroposterior directions. Results of multiple regression analysis showed that with eyes open the 1- to 2-Hz and 2- to 4-Hz sways were related positively to 2,5-hexanedione and inversely with methylhippuric acid. The pattern of changes suggests that the vestibulocerebellar and spinocerebellar afferent systems are asymptomatically affected by n-hexane; the effect of n-hexane on the vestibulocerebellar system is possibly inhibited by xylene.

Cerebellum↗
PubMed2000

Subclinical neurophysiological effects of lead: A review on peripheral, central, and autonomic nervous system effects in lead workers.

BACKGROUND: The peripheral nerve conduction velocity (NCV), distribution of nerve conduction velocities (DCV), somatosensory, visual, and brainstem auditory evoked potentials (SEP, VEP, and BAEP, respectively), event-related potential (P300), computerized static posturography with spectral analysis (postural balance), and electrocardiographic R-R interval variability (CV(RR)) with spectral analysis appear to be promising techniques for assessing subclinical effects of lead on the peripheral, central and autonomic nervous systems. This article presents an overview of research addressing subclinical neurophysiological effects of lead in workers exposed to lead. METHODS: We reviewed 102 articles to examine the effects and dose-effects relationships of lead on peripheral, central, and autonomic nervous system function together with reversibility of the effects, interaction between lead and other metals, and relative sensitivity and specificity of each technique. Background and methodology were also reviewed. RESULTS AND CONCLUSION: Available data suggest that, on a group basis, the reduction in the NCV, together with the effects on the P300 latency, postural balance, and CV(RR), occurs at a mean blood lead concentration (BPb) as low as 30-40 microg/dL; the effects on the latencies of the short-latency SEP, VEP, and BAEP, as well as the DCV, start at a BPb as low as 40-50 microg/dL. Further cross-sectional and preferably prospective studies by using each of those methods are needed to establish more precise dose-effects (and response) relationships of lead.

Autonomic Nervous System↗
PubMed1982

[Statokinesimetry on a tilting platform (author's transl)].

Using a statokinesimeter which records displacements of the center of gravity, the reactions of the postural balance were registered. A test battery with the Romberg-test, the Tandem-Romberg, and two performances on a tilting table is presented. The different gradings of the test battery can be used for quantification of the severity of vestibular disturbances. The findings in 117 healthy persons were compared to those in 46 patients with vestibular disorders. It is suggested that clinical application of this method may be useful. The influence of age, height, and weight is demonstrated.

Adult↗
PubMed1998

The influence of exercise and dehydration on postural stability.

The aim of this study was to investigate the effects of exercise-induced and thermal dehydration on postural balance. Eight male subjects cycled for 2 h at a power output equal to 57-63% VO2max on two different occasions: once without drinking (NF) and once with intake of 1.9 l of a carbohydrate-electrolyte solution (FR). Before and after the exercise test, the velocity of the centre of pressure (COP) excursion was measured on a force platform during 30-s bipedal standing in normal position, feet side by side, and tandem position, feet heel to toe. On another occasion, eight subjects underwent seven consecutive sauna sessions (85 degrees C, 50% rh) of 15 min duration with no fluid replacement (S) to induce thermal dehydration. Mean fluid loss was 2.7 (+/- 0.4)%, 0.5 (+/- 0.5)% and 3.0 (+/- 0.6)% of body mass after NF, FR and S, respectively. Mean velocity of COP excursion after the exercise test was significantly higher in the NF than in the FR trial (p < 0.05). Postural stability was not influenced by S. In conclusion, prolonged exercise without fluid ingestion seems to negatively affect postural stability, whereas no effect is observed after exercise with fluid replacement or after thermal dehydration.

Adult↗
PubMed1994

[The protocol for the vestibulospinal system study by means of a dynamometric platform. Patterns of normalcy].

The Posturography, the recording of the postural balance in standing position, allows the assessment of the vestibulospinal function, through the shifts of the pressure center. In this paper are expressed the results gained with this static posturographic protocol followed at our Department, using a dynamometric platform DINASCAN (Institute of Biomechanics, Valencia, IBv) in 63 normal people. Four parameters (i.e. maximal extent of antero-posterior displacement: lateral wards; full length of the shifting; and the surfaced limited for the changes of the pressure center) in 6 several body positions (Romberg with open and closed eyes; closed eyes and overextended head; closed eyes and right and left cervical turn and standing on only one foot with open eyes) were evaluated. The outcome of the proofs become gradually worsened in accordance with the difficulties of the tests, although there were no differences when considering the results of the proofs with turning or hyperextending the head. Diagnostic possibilities trying dynamometric platforms are considered.

Adult↗
PubMed1998

[Customized 3D radiographic reconstruction of the human pelvis].

The pelvis is an essential element in the study of scoliosis since it constitutes the base of the spine and its orientation may affects postural balance. In order to study the role of the pelvis in the evolution and treatment of this disease, a new technique for the 3D personalised reconstruction of the pelvis was developed. It consists in identifying and digitizing 19 pelvic anatomical landmarks on postero-anterior and lateral x-rays and to reconstruct them in 3D with two techniques: the DLT algorithm developed by Marzan (1976) and, for 6 of the 19 landmarks, an adaptation of it called DLT with confidence coefficients. The latter takes into account the confidence given to the identification of the landmarks on each x-rays. Two methods were used to validate the reconstruction of the pelvis. The first one, used for 11 scoliotic patients and 2 dry pelvis specimens, consists in applying the reconstruction algorithm in an inverse way on the 3D coordinates of the reconstructed landmarks to obtain their 2D retroprojection on the x-ray planes, and thus comparing the retroprojected coordinates with the 2D digitized coordinates. The second method consists in measuring a dry pelvis specimen and comparing the 3D measured landmarks with the ones reconstructed with the x-rays of this specimen. For the first validation, results have shown that the lowest retroprojection errors (less than 2.5 +/- 2.6 mm) for the scoliotic patient group are located on the superior base of the sacrum, on the sacral curve and on the acetabula, while the highest (6.4 +/- 7.2 mm) were on the iliac crests. For the dry specimens, the retroprojection errors were below the millimeter. The second validation method showed 3D differences of 2.4 +/- 1.2 mm between measured and reconstructed landmarks of a dry specimen, which is of the same order of magnitude as what is reported in the literature for vertebrae. The reconstruction of the pelvis is thus considered adequate and its graphical wireframe representation allows to visualise and measure clinical indices concerning its orientation in space. Moreover, the reconstructed landmarks will be used to develop a personalised geometrical and mechanical model of the pelvis which, when integrated with the one for the spine and rib cage, will allow to simulate in a more realistic manner the biomechanical behaviour of the scoliotic trunk, particularly for the study of orthopaedic treatments with braces leaning on it.

Acetabulum↗
PubMed1979

Evidence that a nigral gabaergic--cholinergic balance controls posture.

The intranigral injection of kainic acid (k.a.) (3.5 nM/s.n.) produced a lesion which resulted in a decreased muscarinic receptor binding capacity and in a decreased choline acetyl transferase (CAT) activity confined to the pars reticulata. The unilateral, intranigral injection of carbachol in the substantia nigra (s.n.) produced turning, ipsilateral to the injected side, of dose-related intensity, which was antagonized by scopolamine given either i.p. or intranigrally together with carbachol. The bilateral, intranigral injection of carbachol produced rigid catalepsy, highly resistant to apomorphine administration and antagonized by scopolamine. On the other hand, the catalepsy produced by intranigral picrotoxin was much more sensitive to apomorphine and was disrupted by systemic scopolamine administration. Intranigral scopolamine per se produced either contralateral turning or stereotyped movements consistently, when injected unilaterally or bilaterally, respectively. In addition, scopolamine injected bilaterally in the s.n. but not in the caudate nucleus (c.n.), at the concentration of 64 nM side, was able to antagonize the haloperidol-induced catalepsy and to prevent the tremors and the muscular rigidity produced by arecoline. This effect of scopolamine was surmountable with a higher dose of arecoline. Finally, intranigral muscimol (0.44 nM/s.n.) prevented the occurrence of the parkinsonian syndrome produced by systemic arecoline. It is concluded that the muscarinic receptors present in the s.n. pars reticulata play a role in the control of posture opposite to that of the nigral GABA receptors.

Animals↗
PubMed2006

Balance lower limb loads and 3D spine modifications after total hip joint replacement: effects of leg length discrepancy correction.

Following total hip joint replacement (THJR), the durability of a prosthesis is limited by: wearing of frictional surfaces and loosening and migration of the prosthesis-cement-bone system. Literature review witnesses biomechanical studies focused mainly/only on hip functional state while none of them approached leg length discrepancy (LLD), posture unbalancing or spine related problems after THJR. Conversely, these latter could be critical elements for surgery and rehabilitation success, given the possible induction of asymmetric loading patterns. This study presents the results obtained by using a recently proposed methodology, to measure 3D subject posture balance and spine morphology and to evaluate its usefulness in individual therapy tuning/follow up. 3D subject's posture has been measured by means of 3D opto-electronic device, force platform and baropodography. 90 subjects after THJR have been included in this study. The subjects have been evaluated in two different epochs: 3 weeks after surgical intervention and after 3 months. 77/90 patients presented a LLD, pelvic obliquity and posture unbalancing. More than 90% of this group showed an overall postural re-balancing induced by the use of simple underfoot wedge. 70/77 patients needed wedge under the healthy side showing the surgical intervention produced a leg lengthening. 60/90 (52 LLD) patients underwent up to now to control and patients who wore the suggested wedge (63.4%) presented an improvement over all the considered quantitative parameters. Patients who wore a shorter than suggested wedge (23.1%), or that did not wear the suggested wedge (13.5%) presented a moderate or significant worsening of their postural balancing respectively.

Adult↗