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PubMedDate not supplied

Posture in systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is a connective autoimmune disease that may involve many organ systems and neural function impairment. Postural apparatus dysfunction in SLE may develop in the case of central and peripheral neural involvement. We studied the presence of postural abnormalities in SLE patients with different degrees of disease activity. Twenty-eight subjects (18 SLE patients and 10 normal controls) underwent postural evaluation by means of Static Computerised Posturography. Disease severity or specific clinical problems did not form selection criteria. Lupus activity was assessed using the Systemic Lupus Activity Measure (SLAM). A statistically significant (p < 0.05) increase in the parameters of trace length, trace surface, trace velocity, standard deviation in velocity, and Fast Fourier trX and Y (FET), were found in both the closed and opened eyes tests, when lupus patients were compared to controls subjects. No significant pattern variation in posture was observed between more active and less active SLE patients. Postural control alterations in SLE may be considered a complication of the chronic autoimmune inflammatory process, independent of disease activity as evaluated by the SLAM index. The site of the neuropathy remains uncertain, although we believe it to be peripheral rather than central in origin due to the absence of symptoms or clinical signs of CNS involvement or vascular degeneration.

Adult↗
PubMed1995

Postural hypotension enhanced by exercise in patients with chronic autonomic failure.

The effect of supine exercise on blood pressure (BP), measured while recumbent and after head-up postural change, was investigated in three groups with marked postural hypotension due to chronic autonomic failure: 15 with associated neurological impairment (Shy-Drager syndrome, SDS, multiple system atrophy); 15 with pure autonomic failure (PAF) and two with a deficiency of the enzyme dopamine beta hydroxylase (DBH deficiency). Fifteen normal subjects were controls. In controls, exercise increased supine BP, and there was no postural fall before or after exercise. In SDS and PAF, however, exercise produced a substantial fall in BP, which was greater in PAF. In both groups, BP fell to a lower level on standing after than before exercise. In DBH deficiency, there was little change in BP with exercise, but BP fell to a lower level on standing after exercise. In all three groups with autonomic failure, there were more symptoms of postural hypotension on standing after exercise. The influence of exercise on both supine and postural BP, therefore, should be considered in the clinical and laboratory assessment of autonomic dysfunction.

Aged↗
PubMedDate not supplied

A preliminary study on the effect of occlusal vertical dimension increase on mandibular postural rest position.

The effect of increasing the occlusal vertical dimension on the mandibular postural relation was studied for eight subjects. Interocclusal rest space measurements were made weekly for 1 month prior and subsequent to increasing the occlusal vertical dimension by 3.5 to 4.5 mm interincisally using luted acrylic resin, complete-arch, fixed partial dentures. Interocclusal rest space measurements were made at the clinical rest position, which was established by requesting the subjects to close in maximum intercuspation and immediately relax their mandible. Interocclusal rest space measurements were also made at the more open resting position when the subjects were repeatedly instructed to relax and lapse into a semi-hypnotic condition termed "relaxed resting posture." Initial speech difficulties and muscle discomfort subsided after 1 to 2 weeks. Analysis of variance using repeated measures showed no significant difference in interocclusal rest space after increasing the occlusal vertical dimension for both clinical rest position and relaxed resting posture. A significant difference was found between clinical rest position and relaxed resting posture (P = .001), and no interaction was determined between clinical rest position, relaxed resting posture, and time.

Adaptation, Physiological↗
PubMedDate not supplied

Postural sway of patients with vestibular disorders during optic flow.

Patients with vestibular orders often complain of sensitivity to moving visual environments, leading to dizziness and imbalance. This study investigated standing postural sway of healthy adults and patients with vestibular disorders in response to optic flow in the central field. Visual conditions of varying properties were presented monocularly with a 60 degrees viewing field. The conditions included: eye open-no flow, eye closed, sinusoidal expansions/contractions at 0.3 Hz, a constant flow giving the appearance of tunnel, and a vertically translating checkerboard. Postural sway, defined in this study as movement of the center of pressure, was recorded using a force platform during presentation of the visual stimuli. Patients with vestibular disorders were found to have a significantly higher magnitude of postural sway than control subjects while viewing central optic flow stimuli. Sinusoidally expanding and contracting optic flow induced postural sway at the stimulus frequency in both the patients and controls; patients, however, had a much larger increase in sway at frequencies near the stimulus frequency. These results suggest that postural control in patients with vestibular disorders is particularly affected by optic flow stimuli to the central region of the visual field.

Adult↗
PubMed1994

Postural changes can reduce leakage in women with stress urinary incontinence.

OBJECTIVE: To assess the efficacy of postural changes, such as crossing the legs, in reducing urine leakage in women with stress urinary incontinence. METHODS: Sixty-five women with urodynamically proven stress incontinence underwent a series of standing cough stress tests in each of four postures: standing, crossing the legs, bending forward from the hips, and a combination of crossing the legs and bending forward. The bladder volume and strength of coughing were standardized, and the volume of leakage in each test was measured as the change in pad weight. RESULTS: The mean loss was 12.3 g (95% confidence interval [CI] 8.5-16.1) in the standing position; this was significantly reduced to 1.3 g (95% CI 0.5-2.1, P < .001) with crossed legs and to 4.7 g (95% CI 1.4-7.7, P < .01) by the combination of crossing the legs and bending forward. Bending forward alone did not reduce fluid loss (mean loss 10.2 g, 95% CI 6.5-13.9). The mean reduction in fluid loss was -14.7 g (95% CI -21.2 to -8.2) using the best posture compared to the standing position. Seventy-three percent of the subjects became continent using one or more postural changes. CONCLUSION: Postural changes are an effective means of reducing urine leakage in women with stress urinary incontinence and should be an integral part of the management of this condition.

Adolescent↗
PubMed1993

[Changing fetal position through maternal posture].

The fetal position of 249 cases in their late pregnancy was detected by ultrasound. The results showed that the position of fetal spine tended to lie on the same side as mother's posture during bedrest just before examination. Fetal posterior or transverse spinal position was prone to occur when mother was on her supine position. The fetal cephalic presentation did not correspond entirely with the fetal spinal position. Eighty of the 249 cases presenting fetal spinal posterior or transverse position were chosen at random and corrected by Sims' or hand-knee posture. The better results were obtained especially by the latter. The success rate of correction by maternal posture was affected by the engagement of fetal head and the volume of amniotic fluid. The mechanism of hand-knee posture was discussed. The result indicated that maternal posturing is a clinically valuable procedure. It may be done during pregnancy or in labor to prevent fetal malpresentation.

Breech Presentation↗
PubMed1993

Exercise ventilatory response to upright and aero-posture cycling.

The aero-cycling posture has become increasingly popular among cyclists. Because of the potential for altered lung mechanics in the aero-cycling posture, the ventilatory and gas exchange profiles of 10 moderately trained males (31.1 +/- 6.3 yr, mean +/- SD) exercising on a cycle ergometer in the upright posture (UC) and aero-cycling (AC) posture were studied. Exercise consisted of 3-min work stages with 50-W incremental changes until volitional exhaustion. Ventilatory and gas exchange responses to exercise were averaged each minute. Maximal oxygen consumption (54.3 +/- 6.3 vs 53.4 +/- 6.9 ml.kg-1.min-1) in the UC and AC were not significantly different. Maximal values for ventilation (132.5 +/- 32.3 vs 128.0 +/- 28.7 l.min-1), tidal volume (2.7 +/- 0.5 vs 2.6 +/- 0.3 1.br-1), breathing frequency (50.0 +/- 8.0 vs 47.0 +/- 5.0 br.min-1), and submaximal ventilatory and heart rate responses in the UC were not significantly different compared with the AC. No significant difference existed between postures for mean inspiratory flow and inspiratory duty cycle at comparable submaximal power outputs. These results indicate that at absolute power outputs, ventilatory responses, as determined by respiratory pattern and timing, and metabolic cost, were similar in the UC and AC. Thus, the AC does not impair physiologic responses to high intensity exercise.

Adult↗
PubMed1995

Postural stability among manganese exposed workers.

Postural stability was investigated by static posturography in 32 manganese exposed workers with exposure duration of 6.6 (range 1.1-15.7) years and 53 referent subjects. The mean current urine manganese concentration for the exposed was 6.0 micrograms/g creatinine (range 0.6 to 53.3). There was no significant differences between both groups for the postural sway parameters obtained during eyes open condition. However, significant differences were observed for L - length of sway path and Vel - mean velocity of the center of pressure along its path. The Romberg Ratios (the relationship between eyes closed/open conditions) for the exposed's Vel, L, and Ao were also significantly different from the referent. The study showed that manganese exposed workers had significantly poorer postural stability compared to a referent group. We postulate that this could be a subclinical effect of manganese on the basal ganglia (pallidus) resulting in the postural instability when the visual input is cut off. Based on the current urinary manganese levels, we were not able to obtain any significant association with the postural sway parameters.

Adult↗
PubMed1996

Mandibular position and head posture as a function of eye dominance.

A recent study conducted at Tufts University, School of Dental Medicine has confirmed the relationship between head posture, mandibular position and eye dominance. The purpose of this study is to assess the temporary eye dominance of children and the change relative to head posture and mandibular position. Twenty children were included in this study after the completion of the ophthalmological exclusion screening. All subjects had the sign of eye dominance screened with eye dominance tests. The mandibular position and the 3-dimensional posture of head were recorded. The eye patches were applied over the dominant eye for one hour to achieve the effect of temporary eye dominance change for 10 children. Ten children had the same procedures except for the eye patch procedure. The reexaminations were performed at the end of one hour visit for both groups. Mandibular midline data revealed no change in both control and experimental group. Statistically significant difference in the transverse plane of head posture was observed by means of Student's t test in experimental group. The mean transverse measurement difference was 14.7 degrees, with a standard deviation of 6.4265 degrees. The T value was 5.66, with a probability of p=0.0003 at DF=9. The differences of positions were not statistically significant (P=0.05) on horizontal and vertical planes. The transverse head postural change has been demonstrated by means of temporary eye dominance change. This study highlights several areas: the importance of clinical intervention in young children, the difference on transverse dimensional change, and the importance of role of pediatric dentistry among interdisciplinary cooperation. Further investigation and early clinical intervention is encouraged.

Child↗
PubMed1996

Effects of hypovolemia and posture on responses to the Valsalva maneuver.

INTRODUCTION: We tested the hypotheses that hypovolemia would result in attenuated elevation in blood pressure, greater baroreflex-mediated tachycardia, and reduced capacity for vasoconstriction during a Valsalva maneuver (VM). METHODS: Heart rate (HR) and mean arterial pressure (MAP) were measured beat-by-beat before strain, during a 15-s VM strain at 30 mmHg expiratory pressure, and post-strain. Eight subjects performed three VM trials in each of three postures (supine, sitting, and standing) under two experimental conditions (normovolemic and hypovolemic). Hypovolemia was acutely induced by a bolus injection of 30 mg furosemide. Each experimental condition was conducted on a different day, separated by one week. delta MAP was used in analyses of phase I, late phase II (an indicator of vasoconstriction) and phase III of VM. The ratio delta HR/delta MAP, an index of nonspecific baroreflex control of HR, was used in analysis of early phase II and phase IV of the VM. RESULTS: Compared to normovolemia, hypovolemia resulted in 12% lower plasma volume (p = 0.0001). delta MAP for both phase I and phase III of the VM differed between postures (p = 0.0132 and p = 0.0003, respectively) and was lower in the hypovolemic condition than in the normovolemic condition for phase I in the standing posture (-5 mmHg, p = 0.0385). CONCLUSIONS: HR and blood pressure responses to alterations in intrathoracic pressure are affected by fluid redistribution (posture change), but not by circulating blood volume. Therefore, our results did not support our hypothesis that hypovolemia would result in attenuated elevation in blood pressure, greater baroreflex-mediated tachycardia, and reduced capacity for vasoconstriction during a Valsalva maneuver. However, moderate hypovolemia can be specifically predicted by the phase I response to a VM performed in the standing posture.

Adult↗
PubMed1996

Chiropractic biophysics technique: a linear algebra approach to posture in chiropractic.

OBJECTIVE: This paper discusses linear algebra as applied to human posture in chiropractic, specifically chiropractic biophysics technique (CBP). MATHEMATICAL ANALYSIS: Rotations, reflections and translations are geometric functions studied in vector spaces in linear algebra. These mathematical functions are termed rigid body transformations and are applied to segmental spinal movement in the literature. Review of the literature indicates that these linear algebra concepts have been used to describe vertebral motion. However, these rigid body movers are presented here as applying to the global postural movements of the head, thoracic cage and pelvis. CONCLUSION: The unique inverse functions of rotations, reflections and translations provide a theoretical basis for making postural corrections in neutral static resting posture. Chiropractic biophysics technique (CBP) uses these concepts in examination procedures, manual spinal manipulation, instrument assisted spinal manipulation, postural exercises, extension traction and clinical outcome measures.

Biomechanical Phenomena↗
PubMed1998

Fetal spinal cord transplants support the development of target reaching and coordinated postural adjustments after neonatal cervical spinal cord injury.

Neonatal midthoracic spinal cord injury disrupts the development of postural reflexes and hindlimb locomotion. The recovery of rhythmical alternating movements, such as locomotion, is enhanced in injured animals receiving fetal spinal cord transplants. Neonatal cervical spinal cord injury disrupts not only locomotion but also skilled forelimb movement. The aims of this study were to determine the consequences of cervical spinal cord injury on forelimb motor function and to determine whether transplants of fetal spinal cord support normal development of skilled forelimb use after this injury. Three-day-old rats received a cervical spinal cord lesion at C3, with or without a transplant of fetal cervical spinal cord (embryonic day 14); unoperated pups served as controls. Animals were examined daily during the first month of life using a behavioral protocol that assessed reflexes, postural reactions, and forelimb motor skills. They also were trained and tested as adults to assess performance in goal-directed reaching tasks. The onset of postural reflexes was delayed in the lesion-only group, and goal-directed reaching and associated postural adjustments failed to develop. The transplant group developed reflex responses and skilled forelimb activity that resembled normal movement patterns. Transplant animals developed both target reaching and accompanying postural adjustments. Target reaching requires integration of segmental, intersegmental, and supraspinal input to propriospinal and motor neurons over many spinal cord levels. Transplants may support the reestablishment of input onto these neurons, permitting the development of skilled forelimb activity after neonatal cervical spinal cord injury. The neuroanatomical reorganization of descending and propriospinal input was examined in the companion paper (Diener and Bregman, 1998).

Animals↗
PubMed1998

Posture and locomotion in the rat: independent or interdependent development?

In this essay, recent research into the relation between postural control and the development of walking in the rat is reviewed. The adult-like walking pattern develops at the 15th to 16th day (P15-P16). Until this age, postural control, as indicated by EMG activity in the longissimus muscle in the trunk, is poorly phased in relation to the stepcycle. After P15-P16, accuracy increases but only after P21 is the adult pattern of EMG activity in the trunk muscles in relation to locomotor activity in the hindpaw muscles established. Neuroanatomical research revealed that those muscles in trunk and extremities which fulfil important postural tasks are innervated by motoneuronal pools containing conspicuous dendrite bundles. These bundles emerge at about the age when the adult type of postural control starts to develop. As spinal transsection at P10 abolishes their development, we hypothesize that the development of dendrite bundles is dependent on the ingrowth or the becoming functional of descending projections. On the basis of the neurophysiological and neuroanatomical results we conclude that the development of postural control, which reaches its final stage 5-6 days after the adult-like pattern of walking has developed, is dependent on the maturation of suprasegmental structures and their spinal projections.

Adult↗
PubMed1998

Effects of hypobaric hypoxia on postural control.

BACKGROUND: While the effects of accelerative forces on the vestibular system have been thoroughly investigated, the effects of hypobaric conditions on the postural system have attracted less attention. The purpose of the study was to investigate if postural control is affected by hypobaric hypoxia. HYPOTHESIS: Moderate hypobaric hypoxia may reduce postural control. METHODS: Subjective and multiple objective measurements of postural control with open and closed eyes were made in 16 military aircrew standing on a static balance platform before, during, and after exposure to an altitude chamber training profile with a maximum altitude of 25,000 ft. RESULTS: No subjective dizziness and no clinical unsteadiness were noted. However, significant changes in body sway were found at the balance platform during hypobaric exposure at 18,000, 14,000 and 8000 ft compared with the baseline registrations. The relative increase in sway movements was greater in the eyes open condition compared with the eyes closed condition, and significant for movements in the anteroposterior plane but not in the lateral plane. Most sway parameters returned to pre-exposure values on return to ground level. CONCLUSIONS: Acute hypobaric hypoxia, corresponding to the tested altitudes, influenced postural control primarily in the anteroposterior plane with eyes open. This is in agreement with other studies showing that vision is the first of the special senses to be altered by lack of oxygen.

Adult↗
PubMed1998

Postural hand synergies for tool use.

Subjects were asked to shape the right hand as if to grasp and use a large number of familiar objects. The chosen objects typically are held with a variety of grips, including "precision" and "power" grips. Static hand posture was measured by recording the angular position of 15 joint angles of the fingers and of the thumb. Although subjects adopted distinct hand shapes for the various objects, the joint angles of the digits did not vary independently. Principal components analysis showed that the first two components could account for >80% of the variance, implying a substantial reduction from the 15 degrees of freedom that were recorded. However, even though they were small, higher-order (more than three) principal components did not represent random variability but instead provided additional information about the object. These results suggest that the control of hand posture involves a few postural synergies, regulating the general shape of the hand, coupled with a finer control mechanism providing for small, subtle adjustments. Because the postural synergies did not coincide with grip taxonomies, the results suggest that hand posture may be regulated independently from the control of the contact forces that are used to grasp an object.

Adult↗
PubMed1993

Modulation of postural wrist tremors by magnetic stimulation of the motor cortex in patients with Parkinson's disease or essential tremor and in normal subjects mimicking tremor.

The effect of magnetic brain stimulation on postural wrist tremor was studied in 10 patients with Parkinson's disease, 12 with hereditary essential tremor, and 10 normal subjects who mimicked tremor by making rapid alternating wrist movements. In all patients and normal subjects, magnetic brain stimulation over the contralateral motor cortex at an intensity approximately 10% above threshold produced the following sequence of events: (1) a small direct electromyographic (EMG) response, followed by (2) suppression of the rhythmic EMG activity responsible for the tremor, before (3) reappearance of the tremor time-locked to the stimulus. It is concluded that magnetic brain stimulation over the motor cortex can modulate the oscillatory mechanisms responsible for the generation of postural tremors. Group analysis revealed that the time to reappearance of rhythmic EMG activity varied significantly with the period of parkinsonian postural tremors, but not with the period of essential or mimicked tremors. Magnetic stimulation also significantly shortened the period of parkinsonian postural tremors, but did not influence the period of essential or mimicked tremors. These behavioral differences indicate differences in the pathophysiological mechanisms underlying parkinsonian postural tremor and essential tremor.

Adult↗
PubMed2005

Anatomy and histochemistry of spread-wing posture in birds. 3. Immunohistochemistry of flight muscles and the "shoulder lock" in albatrosses.

As a postural behavior, gliding and soaring flight in birds requires less energy than flapping flight. Slow tonic and slow twitch muscle fibers are specialized for sustained contraction with high fatigue resistance and are typically found in muscles associated with posture. Albatrosses are the elite of avian gliders; as such, we wanted to learn how their musculoskeletal system enables them to maintain spread-wing posture for prolonged gliding bouts. We used dissection and immunohistochemistry to evaluate muscle function for gliding flight in Laysan and Black-footed albatrosses. Albatrosses possess a locking mechanism at the shoulder composed of a tendinous sheet that extends from origin to insertion throughout the length of the deep layer of the pectoralis muscle. This fascial "strut" passively maintains horizontal wing orientation during gliding and soaring flight. A number of muscles, which likely facilitate gliding posture, are composed exclusively of slow fibers. These include Mm. coracobrachialis cranialis, extensor metacarpi radialis dorsalis, and deep pectoralis. In addition, a number of other muscles, including triceps scapularis, triceps humeralis, supracoracoideus, and extensor metacarpi radialis ventralis, were found to have populations of slow fibers. We believe that this extensive suite of uniformly slow muscles is associated with sustained gliding and is unique to birds that glide and soar for extended periods. These findings suggest that albatrosses utilize a combination of slow muscle fibers and a rigid limiting tendon for maintaining a prolonged, gliding posture.

Animals↗
PubMed2000

Effect of low back posture on the morphology of the spinal canal.

OBJECTIVE: To define the possible mechanism of posture-dependent symptoms of spinal stenosis by measuring the effect of low back posture on morphologic changes of the intervertebral discs and spinal canal in healthy young people. DESIGN: Twenty healthy young volunteers underwent magnetic resonance imaging while supine with their spine in neutral, flexed, extended, and right and left rotational positions. The axial MR images at the middle of the intervertebral discs of L3-4 and L4-5 were analyzed to measure the difference in the size and shape of the intervertebral discs and spinal canal in each posture. RESULTS: Extension or rotation decreased the sagittal diameters and cross-sectional areas of the dural sac and spinal canal and increased the thickness of the ligamentum flavum, whereas flexion had the opposite effects. The gap between the convex posterior disc margin and the anterior margin of the facet joint on each side, represented as the subarticular sagittal diameter, increased with flexion and decreased with extension or rotation. The direction of rotation did not result in asymmetry of the subarticular sagittal diameter, but right rotation caused thickening of the right ligamentum flavum, and vice versa. The shape and dimensions of the disc did not change significantly according to the positions of the low back. CONCLUSIONS: With extension or rotation, the thickness of the ligamentum flavum increased and the posterior margin of the intervertebral disc was approximated to the facet joint without any change in shape and size of the disc. These phenomena result in a decrease in the size of the spinal canal and dural sac in extension or rotation postures in young healthy people without disc degeneration, and may explain the posture-dependent symptom of spinal stenosis.

Adult↗