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At least 1,711 records · Page 95Linked to original sources
PubMed1982

Effects of posture on the spread of spinal anaesthesia with isobaric 0.75% or 0.5% bupivacaine.

In a double-blind study the effects of posture on the spread of 3 ml of isobaric bupivacaine 5 and 7.5 mg ml-1 were compared after intrathecal injection in 40 patients undergoing orthopaedic surgery. Three millilitre of isobaric bupivacaine 7.5 mg mg-1 administered with the patient in a sitting position during and for 2.5 min after injection produced the highest spread of analgesia (T4). Horizontal posture, and the smaller dose in both positions, resulted in spread of analgesia to T7-8. Motor block in the legs was good in all cases. Horizontal posture at the time of injection resulted in the longest mean duration of analgesia and motor block, although there was no statistically significant difference in mean times between the groups. The longest mean duration of pin-prick analgesia (329 +/- 23 min) was in the patients injected in the horizontal posture with bupivacaine 7.5 mg ml-1. The course of anaesthesia and recovery were uneventful in all patients.

Aged↗
PubMed1981

Delayed and enhanced long latency reflexes as the possible cause of postural tremor in late cerebellar atrophy.

The pathophysiology of postural tremor was studied in 7 patients with cortical cerebellar atrophy, and compared with the responses of 14 healthy control subjects to the same tests. Both tibial nerves were simultaneously and selectively stimulated in the fossa poplitea. EMG was recorded from agonist gastrocnemius muscles and from the antagonistic anterior tibial muscles. Displacement of the centre of foot pressure, inclination of trunk and head in the anteroposterior direction, and the ankle angle were also measured. Patients and controls both exhibit a synchronized discharge in the anterior tibial muscle (antagonist) with a latency of 120 ms to stimulus onset (tib1). Tib1 is shown to be a segmental stretch reflex elicited by the contraction of the gastrocnemius (agonist). A later, presumed long-loop response occurs after another 120 ms both in gastrocnemii and anterior tibial muscles in the normal subjects. This latency, and the amplitude of the late reflex, are increased in the patient group. The synchronization of delayed long-loop reflexes and a stretch response of the gastrocnemius in response to tib1 terminate the first cycle of the postural tremor which thereafter continues by way of the same mechanism generating a contraction of the anterior tibial muscle. Postural tremor can thus be synchronized by a single bilateral electrical stimulus and can even be elicited in incipient cases of the disease. With further progression of the cerebellar atrophy the dominant frequency of the postural tremor decreases along with an increase of long-loop latencies.

Atrophy↗
PubMed1997

Postural responses to vibration of neck muscles in patients with idiopathic torticollis.

Vibration of the dorsal muscles of the neck, simulating lengthening, in standing man causes a visible forwards tilt of the body shown on posturography as a tonic sagittal sway deviation. According to the theory that posture is organized with respect to a 'body schema' this deviation is a result of an interpretation of the concurrent neck afferent and vestibular signals. Considering the hypothesis that neck afferent signals may be misinterpreted in patients with spasmodic torticollis (ST) causing abnormal postural responses, we recorded body sway induced by unilateral dorsal neck muscle vibration in 22 idiopathic ST patients (19 treated with botulinum toxin) during upright stance with eyes closed. Comparison groups were 19 normal subjects and 11 patients with bilateral loss of vestibular function (labyrinthine defective, LD) in whom neck afference should be intact. Both treated and untreated ST and LD patients had absent or diminished sway deviations. When sway deviation did occur, it was sagitally oriented as with normal subjects and unrelated to ST head turns. In most ST and LD patients, neck vibration induced neck extension, an effect which is observed in normal subjects only if the torso is retrained. The results suggest that neck proprioceptive input retains local postural functions in ST, however, it is relatively ignored in the context of the whole body postural control and spatial orientation. The mild disorders of vestibular function reported in torticollis patients may be due to an inability to calibrate vestibular signals by reference to corroborative signals from neck proprioception.

Achilles Tendon↗
PubMed1997

Muscle activity adapts to anti-gravity posture during pedalling in persons with post-stroke hemiplegia.

With hemiplegia following stroke, a person's movement response to anti-gravity posture often appears rigid and inflexible, exacerbating the motor dysfunction. A major determinant of pathological movement in anti-gravity postures is the failure to adapt muscle-activity patterns automatically to changes in posture. The aim of the present study was to determine whether the impaired motor performance observed when persons with hemiplegia pedal in a horizontal position is exacerbated at more vertical anti-gravity body orientations. Twelve healthy elderly subjects and 17 subjects with chronic (> 6 months) post-stroke hemiplegia participated in the study. Subjects pedalled a modified ergometer at different body orientations (from horizontal to vertical), maintaining the same workload, cadence, and hip and knee kinematics. Pedal reaction forces, and crank and pedal kinematics, were measured and then used to calculate the work done by each leg and their net positive and negative components. The EMG was recorded from four leg muscles (tibialis anterior, medial gastrocnemius, rectus femoris and biceps femoris). The main result from this study was that impaired plegic leg performance, as measured by net negative work done by the plegic leg and abnormal early rectus femoris activity, was exacerbated at the most vertical body orientations. However, contrary to the belief that muscle activity cannot adapt to anti-gravity postures, net positive work increased appropriately and EMG activity in all muscles showed modulated levels of activity similar to those in elderly control subjects. These results support the hypothesis that increased verticality exacerbates the already impaired movement performance. Yet, much of the motor response to verticality was flexible and appropriate, given the mechanics of the task.

Adaptation, Physiological↗
PubMed1990

Posture of the head, the hyoid bone, and the tongue in children with and without enlarged tonsils.

The purpose of this investigation was to analyse whether there were any differences between children with and without enlarged tonsils with regard to the posture of the head, the hyoid bone, and the tongue. Twenty-two children with enlarged tonsils were compared with a matched normal control group. Of the children in the tonsil group, 59 per cent were mouth-breathers during the day and 82 per cent during the night. None of the control children was a mouth-breather. The results showed that, compared with the control children, children with enlarged tonsils had an extended posture of the head, a lowered position of the hyoid bone, and an antero-inferior posture of the tongue. The vertical position of the hyoid bone also reflected the vertical position of the tongue. The antero-posterior position of the tongue was closely related to the oro-pharyngeal depth. The postural pattern in children with enlarged tonsils appears to be associated with the need for maintenance of free oro-pharyngeal airway capacity.

Adolescent↗
PubMed1998

Head posture and malocclusions.

The present study aimed to examine whether any pattern of associations could be found between the posture of the head and neck, and the occurrence of malocclusions. The sample comprised 96 children (45 M, 51 F) aged 7-13 years, sequentially admitted for orthodontic treatment of severe malocclusions. Malocclusions were diagnosed clinically and classified into occlusal, spacing, and dentitional anomalies and their subdivisions. Craniovertical, craniocervical, and cervicohorizontal postural variables were recorded from lateral cephalometric radiographs taken with the subject standing with the head in the natural head position (mirror position). A clear pattern of associations between crowding and craniocervical posture was found. Subjects with anterior crowding, i.e. more than 2 mm lack of space in the upper or lower anterior segments of the dental arch, had craniocervical angles that were on average 3-5 degrees larger than subjects without crowding (P < 0.05, P < 0.01). The findings were in agreement with the soft tissue stretching hypothesis, according to which the sagittal development of the dentoalveolar arches is impeded by the increased dorsally-directed soft tissue pressure in subjects with extended craniocervical posture.

Adolescent↗
PubMed2002

Biomechanical influences of head posture on occlusion: an experimental study using finite element analysis.

The biomechanical influences of head posture on the cervical column and craniofacial complex during masticatory simulation were quantified using three-dimensional (3D) finite element analysis (FEA). Three types of finite element model (FEM) were designed to examine relationships between the position of the head and malocclusion. Model A was constructed to have a standardized cervical column curve, model B a forward inclined posture, and model C a backward inclined posture. The results of the spinal displacements revealed that model B moved in a forward direction and model C in a backward direction during masticatory simulation. The stress distributions on the cervical column (C1-C7) for models A, B, and C showed differences; stress converged at the atlas in model A, high-level stresses were observed at the spinous processes of C6 and C7 in model C, and the stress converged at the anterior edge in the vertebral body of C4 of model B. Stress distribution on the occlusal plane and maxillofacial structure did not show absolute differences among the three models. Alteration of head posture was directly related to stress distribution on the cervical column, but may not always directly influence the occlusal state.

Biomechanical Phenomena↗
PubMed2005

Molar bite force in relation to occlusion, craniofacial dimensions, and head posture in pre-orthodontic children.

The present study examined bite force in relation to occlusion, craniofacial dimensions, and head posture. The sample comprised 88 children (48 girls, 40 boys) aged 7-13 years, sequentially admitted for orthodontic treatment of malocclusions entiling health risks. Bite force was measured in the molar region by means of a pressure transducer. Angle classification, number of teeth and contact in the intercuspal position (ICP) were recorded and dental arch widths were measured on plaster casts. Craniofacial dimensions and head posture were recorded from lateral cephalometric radiographs taken with the subject standing with their head in a standardized posture (mirror position). Associations were assessed by Spearman correlations and multiple stepwise regression analyses.The maximum bite force increased significantly with age in girls, with teeth in occlusal contact in boys, and with increasing number of erupted teeth in both genders. Bite force did not vary significantly between the Angle malocclusion types. Only in boys was there a clear correlation between bite force and craniofacial morphology: cranial base length (n-ba, n-ar), posterior face height (s-tgo, ar-tgo), vertical jaw relationship (NL-ML), mandibular inclination (NSL-ML), form (ML-RL) and length (pg-tgo), and inclination of the lower incisors (Ili-ML). Multiple regression analysis showed that the vertical jaw relationship (P < 0.001) and the number of teeth present (P < 0.01) were the most important factors for the magnitude of bite force in boys. In girls, the most important factor was the number of teeth present (P < 0.001). No correlations between bite force and head posture were found.

Adolescent↗
PubMed1988

Age-related changes in anticipatory postural adjustments associated with arm movements.

This study investigated the effects of age on the feedforward activation of postural muscles in advance of reaction time arm movements. Fifteen young (mean age 26 years) and 15 older (mean age 71 years) adult subjects were instructed to rapidly push or pull on a hand-held manipulandum. Postural muscle response onset latencies of the lower leg were significantly increased in the older adult group in three of the four conditions when compared to the young adult group. In addition, prime mover muscle response onset latencies of the upper arm showed a large, significant increase in older adults beyond that due to the slowing of the postural response. The results suggest two conclusions. The voluntary control system may be affected to a slightly greater degree with age resulting in slower voluntary movement in the elderly. Or, deterioration of the postural control system with age slows the speed of voluntary movement by delaying the onset of the voluntary muscle response.

Adult↗
PubMed1989

Changes in head posture and nasopharyngeal airway following surgical correction of mandibular prognathism.

It was the aim of the present study to cast light on the role of the mandible in relation to head posture and airway space by evaluating patients before and after surgical correction of mandibular prognathism. The material comprised standardized profile cephalograms of 52 patients with mandibular prognathism. All patients had received orthodontic adjustments prior to mandibular osteotomy. Mean age of the patients was 24.3 years, and 12 males and 40 females participated in the study. The first profile radiograph of each patient was obtained the day before surgery in the natural head (mirror) position. All patients underwent mandibular surgery with a bilateral vertical ramus osteotomy. Approximately one year after surgery, the cephalometric investigation was repeated. Head posture was evaluated by the craniocervical angulation (NSL/CVT and NSL/OPT) and airway space as nasopharyngeal airway size (ad1 and ad2). Changes in posture and airway (ex.2-ex.1) were evaluated by paired t-tests. The results showed a mean increase in head posture of 2.7 degrees (p less than 0.001) and a mean reduction in airway space of 2.3 mm (p less than 0.001).

Adolescent↗
PubMed1982

Treatment of functional chronic stooped posture using a training device and behavior therapy. A case report.

Functional posture problems and related gait problems are often difficult to manage clinically because of the difficulty of providing immediate feedback to clients during walking or standing and because of secondary personal gains provided the client for having the "disability." This article describes an inexpensive posture training device and treatment of a client with developmental disabilities and a long history of posture problems and secondary gait pattern abnormalities. Thirty-six short training sessions, coupled with a supportive daily living situation, produced marked improvements in the client's posture and gait.

Adult↗
PubMed1988

Modification of sitting posture of patients with hemiplegia using seat boards and backboards.

The purpose of this study was to evaluate and compare the effects of using seat boards only and a combination of seat boards and backboards on wheelchair posture. Forty-one patients with hemiplegia secondary to cerebrovascular accidents were assigned sequentially to 1) a group that used seat boards only (SB Group), 2) a group that used both seat boards and backboards (SBB Group), or 3) a group that used no boards (Control Group). The SB and SBB Groups used the boards throughout rehabilitation. Wheelchair sitting posture was measured at entry to and discharge from the rehabilitation program. The SB and SBB Groups were measured with and without boards. Anterior-posterior pelvic tilt, lumbar lordosis, thoracic kyphosis, lateral flexion, and lateral pelvic tilt were measured using a gravity goniometer, photographs, and calipers. Use of seat boards was associated with a decreased lateral pelvic tilt of 2.3 degrees at discharge while the seat boards were in place. The use of seat boards and backboards combined was associated with decreased lateral pelvic tilt of 3.1 and 1.6 degrees, increased anterior pelvic tilt of 13.1 and 11.1 degrees, and decreased thoracic kyphosis of 13.0 and 14.2 degrees at entry to and at discharge from the rehabilitation program, respectively, while the boards were in place. At the end of rehabilitation when the boards were removed, no long-term postural changes had occurred in the treatment groups compared with the Control Group. This study demonstrated that seat boards and backboards in wheelchairs improve certain postural deviations of patients with hemiplegia, but that these improvements are not maintained when the boards are removed after 5 to 10 weeks of use.

Analysis of Variance↗
PubMed1998

The relationship between head and neck posture and VDT screen height in keyboard operators.

BACKGROUND AND PURPOSE: The purpose of this study was to determine the effect of change in video display terminal (VDT) height from desktop height (96.5 cm [38 in]) to an elevated position (109.2 cm [43 in]) on postural angles of the head and neck and the effect on cervical spine flexion moments. SUBJECTS: Twenty-seven persons (3 male, 24 female) who spent at least 3 hours per day using a computer while seated were the subjects. The subjects had a mean age of 36.7 years (SD=6.0, range=25-47). METHODS: Subjects were photographed over two 10-minute periods while seated using a computer with the VDT at two different heights. Later, a goniometer was used over images to record angles. RESULTS: There was no difference in cervical flexion moment between the two screen positions. Several postural angles of the head and neck showed changes, but the clinical relevance of these changes is questionable. CONCLUSION AND DISCUSSION: Changing the VDT height from 96.5 to 109.2 cm (floor to midscreen) has no effect on flexion moment on the cervical spine during short periods of VDT operation. If flexion moment is considered a biomechanical indicator of postural stress, it does not appear that the elevated screen position reduces postural stress on the cervical spine during short periods of VDT operation.

Adult↗
PubMed1998

Relationship between standing posture and stability.

BACKGROUND AND PURPOSE: This study determined whether persons with stability impairments have postural aberrations. We investigated whole-body posture and its relationship to center-of-gravity (COG) stability. SUBJECTS: Data from 27 subjects with vestibular hypofunction and 26 subjects without vestibular impairment were analyzed. METHOD: An optoelectronic full-body system measured kinematics. Force plates measured ground reaction forces while subjects stood with their feet 30 cm apart and eyes open and with their feet together and eyes closed. RESULTS: The subjects with vestibular hypofunction demonstrated less stability than the subjects without impairment, but there were no postural differences. Subjects with vestibular hypofunction had more weight on the left lower extremity during standing with feet apart. In all subjects in both groups, during standing with feet apart, the COG was anterior to the ankle, knee, back, and shoulder and posterior to the hip and neck. Subjects had an anterior pelvic tilt, extended trunk and head, right laterally flexed trunk and pelvis, and flexed knees. With their feet together, subjects increased their anterior pelvic tilt; trunk, head, and knee flexion; and anterior COG position. CONCLUSION AND DISCUSSION: Posture and stability had a low correlation. Subjects with bilateral vestibular hypofunction did not demonstrate a forward head or backward trunk lean, as has been reported anecdotally. Changing from standing with feet apart to feet together increased whole-body movement patterns to control standing stability.

Adult↗
PubMed2001

Influence of sleep posture on response to oral appliance therapy for sleep apnea syndrome.

STUDY OBJECTIVE: This study evaluated the effect of sleep posture on oral appliance therapy to elucidate the interindividual difference of response to the device. DESIGN: Seventy-two unselected patients with sleep apnea syndrome were studied polysomnographically before and after insertion of the individually fabricated and adjusted device. Sleep positions were measured using a body position sensor. The patients were classified into three groups; supine, lateral and prone groups, according to the position in which apneas were most frequently observed. SETTING: N/A. PATIENTS OR PARTICIPANTS: N/A. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: The mean apnea-hypopnea index (AHI) of all patients before treatment [43.0+/-25.6 (SD)] was significantly (p<0.0001) decreased after insertion of the appliance (21.6+/-18.3). The device decreased the mean AHI significantly from 29.8 to 11.3 in the supine position and 5.5 to 1.6 in the prone position, and increased, but not significantly, from 7.7 to 8.7 in the lateral posture. The supine (n=44) and prone (n=13) groups showed significant reduction of AHI with the oral appliance, while the lateral group (n=15) revealed only a slight decrease, although not significantly. Responders defined by AHI<10 accounted for 61.4% in the supine group, 0% in the lateral group and 84.6% in the prone group. Responders defined by a 50% drop in AHI accounted for 84.1%, 6.7%, and 46.7%, respectively. CONCLUSIONS: The effectiveness of oral appliance therapy is greatly influenced by sleep posture. Sleep posture recorded by polysomnography may be useful to predict the future success or failure of the device.

Aged↗
PubMed1998

Postural control, attention and sleep deprivation.

We investigated the effect of sleep deprivation on postural control during a simple reaction time task (SRT), during a task requiring the intermittent inhibition of a reaction (IRT), and in the absence of a concurrent information processing task. Postural sway, i.e. changes in center of pressure on a force platform, was recorded in three increasingly difficult standing conditions (fixed platform, sway-referenced platform and sway-referenced platform with sway-referenced visual scene) during the three information-processing task conditions. Five healthy subjects performed the tasks either after normal sleep or following 24 h of sustained wakefulness. As hypothesized, sleep deprivation significantly increased postural sway only in the IRT condition. Within the IRT condition, sleep deprivation significantly increased sway across all postural conditions.

Adult↗
PubMed1999

Effect of articulatory and mental tasks on postural control.

The present study sought to determine whether the increased postural instability produced by a spoken mental task was due to competing demands for attentional resources or perturbation of posture by articulation. Postural sway was measured in 36 normal subjects under the following conditions: repeating a number aloud (articulation), counting backwards aloud in multiples of seven (articulation and attention), counting backwards silently (attention), and no mental task (neither articulation nor attention). Articulation resulted in a significant increase in sway, whereas no effect of attention was observed. We conclude that in order to accurately assess the effect of attentional demands on postural control, it is important to eliminate or control the effects of articulation.

Adolescent↗
PubMed2001

Postural effects on brain hemodynamics in unilateral cerebral artery occlusive disease: a positron emission tomography study.

To investigate effect of assuming of upright posture on brain hemodynamics in patients with unilateral internal carotid or middle cerebral artery occlusion (MCAO), local tissue oxygen extraction fraction (OEF), and postural changes in regional cerebral blood flow (rCBF) during supine and sitting conditions were examined using positron emission tomography (PET) with (15)O-gas steady-state method and H(2)(15)O autoradiographic method. A total of 22 minor stroke patients at relatively early stages participated. The regions of interest method was used for analyzing levels of perfusion and oxygen metabolic parameters, and postural rCBF change within MCAO group was investigated using statistical parametric mapping. Region of interest analyses showed significant rCBF reduction in the cortical and subcortical regions distal to the artery occlusion in CAO patients during sitting. Regression analyses showed that magnitudes of rCBF reduction in those areas were correlated positively with OEF values and inversely with metabolic rates of oxygen (P < 0.05). Statistical parametric mapping for MCAO patients demonstrated further rCBF reduction by sitting in the occlusion-side MCA territory. The current study suggested that assumption of upright posture could exert an adverse effect on local perfusion in hemodynamically compromised patients with major cerebral vessel occlusion, possibly caused by impairment of local autoregulation.

Adult↗