Bicarbon valve -- European multicenter clinical evaluation

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.     

The relationship between surface contour and vertebral body measures of upper spine curvature

STUDY DESIGN: In this study, parameters of sagittal cervical posture obtained from surface markers and from vertebral body locations were compared. OBJECTIVES: Several postural parameters were examined to establish the degree to which surface measures of cervical alignment reflect the underlying vertebral body alignment. SUMMARY OF BACKGROUND DATA: Previous studies of the relation between surface and vertebral alignment in the thoracic and lumbar regions have shown conflicting results. Some data suggest a connection between surface cervical posture and head and neck pain, but the relation between surface and vertebral posture in the cervical region has not been reported. METHODS: Lateral view radiographs of 24 healthy volunteers were used to give the surface alignment of skin markers and the locations of the geometric centers of vertebral bodies. Three angles describing sagittal alignment were investigated: 1) forward inclination of C2 relative to C7 (cervical inclination); 2) cervicothoracic kyphosis; and 3) cervical lordosis. RESULTS: A strong relationship between surface and vertebral data was not established. Two factors were identified as contributing to the observed differences: length of spinous processes and depth of soft tissue overlying the spinous processes at each spinal level. CONCLUSIONS: The assumption that the surface curve is the same as the vertebral curve is not supported by these results, suggesting caution is needed in inferring vertebral alignment from observed surface contours.     

Sex differences in discriminative stimulus and diuretic effects of the kappa opioid agonist U69,593 in the rat

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.     

Postural changes of the cervical spine in patients with nontoxic goiter

PURPOSE: To investigate differences in cervical spine posture and range of motion and self-reported neck pain and headache between patients with nontoxic goiter compared with a matched control group. DESIGN: An observational, controlled, blinded study. SETTING: The ambulatory outpatient facility of a university hospital. PARTICIPANTS: Twenty-five nontoxic goiter patients and 25 matched nongoiterous control subjects from the Department of Endocrinology. INTERVENTION: Participants were X-rayed from a lateral position in neutral, full flexion and full extension, and the radiographs were evaluated by a blinded examiner for anterior head carriage, maximal flexion, maximal extension and the extent and severity of any degenerative changes in the cervical spine. The degree of postural neck muscle tenderness was evaluated by a blinded rheumatologist using a validated Total Tenderness Score system. In addition, the two groups were compared for their self-reported frequency of neck pain and headaches. RESULTS: A significant increase in anterior head carriage was found among the goiter patients (p = .01), together with a corresponding decrease in flexion (p = .01), whereas the corresponding increase in extension was not statistically significant (p = .16). A higher prevalence of headaches was found in the goiter group (p = .06), but there was no difference in neck muscle tenderness (p = .40) or frequency of neck problems (p = .40) between the groups. The severity of degenerative changes in the cervical spine (p = .22) and the number of vertebral levels with degenerative changes (p = .13) were similar in the two groups. CONCLUSIONS: Goiters of > 100 g seem to alter the posture of the cervical spine, possibly resulting in a tendency for more frequent headaches. The changes do not seem to cause more neck pain, muscle tenderness or degeneration of the cervical spine.     

Influence of head position on dorsal neck muscle efficiency

The aim of this study was to assess the influence of head position on dorsal neck muscle efficiency in the sagittal plane. Fifteen subjects participated. The EMG versus isometric extension moment of dorsal neck muscles was studied in neutral (with subject gazing on a horizontal plane), cervical flexed, and cervical extended positions. A vectorial construction was created by means of photographs to calculate the extension moment which balances measured pulling force and gravitational force in isometric conditions. The maximum extension was highest in neutral position. The EMG/moment relationship was non-linear. The ratio between the EMG and the generated moment differed significantly in the three positions (p < 0.01) and was lower in neutral position. These results demonstrate the influence of head position on dorsal neck muscle efficiency; muscles appeared most efficient in neutral position. Muscle length, depending on head position, is probably the main influencing factor.     

Differences in Epstein-Barr virus expression between primary and secondary cutaneous angiocentric lymphomas. French Study Group of Cutaneous Lymphomas

OBJECTIVE: The aim of this investigation was to report on the radiographic interpretation of the hard palate and nasal fossa floor in panoramic radiographs by studying different skulls, x-ray machines, and head positions in relationship to the Frankfort plane before and after ostectomy. STUDY DESIGN: Twenty dry human skulls were radiographed with three different panoramic x-ray machines in three different positions. Three of the skulls were submitted to different ostectomies. RESULTS: Multiple images of the hard palate and nasal fossa floor were present in 96.12% of the radiographs. Single images (3.88%) occurred only in the "chin up" position. CONCLUSIONS: The lower image represents the nasal fossa floor, especially its lateral and anterior limits. The upper images are double real images mainly formed by the junction of the nasal septum with the nasal fossa floor and possibly by posterior parts of the hard palate and nasal fossa floor. All images overlap in the "chin up" position becoming a single image. The most common shape of the anatomic landmark was wide angle "W" (58.33%). Other shapes present in positions "chin up" and "chin down" indicate patient positioning errors. The x-ray machines did not influence the results.     

Renal function tests for windows--a model for the development and distribution of medical software on the Internet

In the present study, pharyngeal size was investigated on the lateral cephalometric head films of 90 subjects, 45 males and 45 females, having different ANB angles. All of the subjects were aged 13 to 15 years. The films were taken at natural head position, and all were divided into three groups according to the ANB angle: ANB angles smaller than 1 degree, between 1 degree and 5 degrees, and larger than 5 degrees. In addition, each group was also divided into two subgroups according to sex. The effects of the ANB angle and sex on the pharyngeal size were investigated by means of variance analysis. It has been observed that two measurements, hy-apw4 and oropharynx area measurements, were affected by the change of ANB angle, and two other measurements, t-ppw and hy-apw2 measurements, by the sex; and that hy-apw4 measurement and oropharynx area became smaller with the increase of ANB angle.     

When dynamic, the head and face alone can express pride.

Prior research suggested that pride is recognized only when a head and facial expression (e.g., tilted head with a slight smile) is combined with a postural expression (e.g., expanded body and arm gestures). However, these studies used static photographs. In the present research, participants labeled the emotion conveyed by four dynamic cues to pride, presented as video clips: head and face alone, body posture alone, voice alone, and an expression in which head and face, body posture, and voice were presented simultaneously. Participants attributed pride to the head and face alone, even when postural or vocal information was absent. Pride can be conveyed without body posture or voice. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Effects of postural change on aspiration in head and neck surgical patients

This study was designed to define the effects of postural change on liquid aspiration during videofluorographic examination of oropharyngeal swallow in head and neck surgical patients. Thirty-two patients were given two swallows of five different amounts of liquid barium as tolerated. When aspiration occurred, the patient's head and/or body position was changed, new posture being determined by the swallowing disorder identified as the cause of the aspiration. Postural techniques were successful in eliminating aspiration on at least one volume of liquid in 81% of these patients. Patients in all surgical groups were able to use postures with equal success. A variety of positions were used in each type of surgical patient, indicating that these patients exhibited a variety of swallowing problems. Results emphasize the importance of introducing postural techniques during the radiographic study of oropharyngeal swallow to facilitate safe oral intake of liquids.     

Kinematic data on primate head and neck posture: implications for the evolution of basicranial flexion and an evaluation of registration planes used in paleoanthropology

Kinematic data on primate head and neck posture were collected by filming 29 primate species during locomotion. These were used to test whether head and neck posture are significant influences on basicranial flexion and whether the Frankfurt plane can legitimately be employed in paleoanthropological studies. Three kinematic measurements were recorded as angles relative to the gravity vector, the inclination of the orbital plane, the inclination of the neck, and the inclination of the Frankfurt plane. A fourth kinematic measurement was calculated as the angle between the neck and the orbital plane (the head-neck angle [HNA]). The functional relationships of basicranial flexion were examined by calculating the correlations and partial correlations between HNA and craniometric measurements representing basicranial flexion, orbital kyphosis, and relative brain size (Ross and Ravosa [1993] Am. J. Phys. Anthropol. 91:305-324). Significant partial correlations were observed between relative brain size and basicranial flexion and between HNA and orbital kyphosis. This indicates that brain size, rather than head and neck posture, is the primary influence on flexion, while the degree of orbital kyphosis may act to reorient the visual field in response to variation in head and neck posture. Regarding registration planes, the Frankfurt plane was found to be horizontal in humans but inclined in all nonhuman primates. In contrast, nearly all primates (including humans) oriented their orbits such that they faced anteriorly and slightly inferiorly. These results suggest that for certain functional craniometric studies, the orbital plane may be a more suitable registration plane than Frankfurt "Horizontal."     

Lateral teleradiography of the cranium: the effect of head positioning in the interpretation of cephalometric tracings. An experimental study on a phantom

PURPOSE: To assess the influence of head mispositioning during lateral teleradiography of the skull for cephalometric purposes. MATERIAL AND METHODS: We used a human dry skull fixed on a professional support at a three level angular scale to quantitate lateral and anteroposterior rotations and inclinations. We took 15 radiographs at different angles (-2 degrees and -4 degrees right rotation; +2 degrees and +4 degrees left rotation; -2 degrees and -4 degrees anterior roll; +2 degrees and +4 degrees posterior roll; -2 degrees and -4 degrees right pitch; +2 degrees and +4 degrees left pitch; + 2 degrees left rotation and -2 degrees anterior roll; +2 degrees left rotation and +2 degrees left pitch). RESULTS: The analysis of the 15 radiographic tracings compared with the one obtained with the head positioned correctly showed no substantial differences in angular and linear values; no difference was such as to invalidate tracing. DISCUSSION: When skull malpositioning limited within 4 degrees, the angular and linear measurements of the cephalometric tracing are reliable and accurate. Nevertheless, cephalometric findings must always be integrated with clinical and history data. CONCLUSIONS: We believe that even less than perfect teleradiographs of the skull should be used for cephalometric purposes because, even though they require more care of the dentist to analyze them, the results are reliable and the patient is spared further X-ray exposure.     

Probable torticollis revealed in decapitated skull

The skeletal features of a moderately decomposed decapitated head recovered in 1993 are consistent with torticollis (wryneck) and inconsistent with other possible syndromes. Asymmetries of the face, cranial vault, mandible, and cervical vertebrae closely resemble published cases of paleopathological and recent torticollis. The laterally directed left occipital condyle and articulation of the basicranium and cervical vertebrae indicate that the head was tipped toward the left shoulder. Right-left asymmetries of areas of muscular attachments are compatible with a leftward head deviation. Mild arthritis of the atlantal-occipital and intervertebral joints, clinoid bridging, and thickening of the inner table of the frontal squamosa may not be related to the possible torticollis. The postural deviations of the head and neck may aid in the identification of this homicide victim, as did skeletal evidence to torticollis in an earlier case from Britain.     

Quality of corneal donor tissue in the greater-than-75-year age group

Impaired nasal breathing has been reported to cause changes in human head posture. The aim of this study was to assess whether there was any relationship between nasorespiratory function and variables of head posture in 58 young adults. The pressure flow technique was used to measure airflow rate and oral/nasal pressure and to calculate the smallest cross-sectional area of the nasal airway. A natural head position roentgenocephalogram was used to measure the craniovertical angulation (NSL/VER), craniocervical angulation (NSL/OPT), and cervical spine inclination (OPT/HOR). The results showed a trend toward enlarged craniocervical angulation and forward inclination of the cervical spine in subjects with a relatively large nasal cross-sectional area. Though the general opinion on the effects of reduced upper airway size on head posture is opposite, these results are an experimental confirmation of the theoretically expected mechanism that leads to increased head extension in obstructed subjects.     

Electromyographic activity of the cervical musculature during dynamic lateral bending

STUDY DESIGN: Electromyographic profiles from the neck muscles of five young, healthy men were obtained to study the muscular, activation patterns during dynamic external loading. OBJECTIVES: To examine the myoelectric activity of selected cervical muscles during dynamic loading, and to explore the reaction of the cervical muscles to different loading conditions. SUMMARY OF BACKGROUND DATA: The response of cervical muscles throughout dynamic external loading is not well understood. Electromyography provides information, within certain limitations, about the neural drive to various components of the musculature. Such information on activation, combined with geometric parameters of the musculoskeletal tissues, constitutes a tool for helping to understand the mechanism of head and neck impact-related injury. METHODS: Subjects were tested with the head and neck in the neutral and prebent positions. Dynamic loads were applied laterally to each subject by free-falling masses to create peak dynamic loads ranging from about 40 to 100 N. Force and electromyographic data were recorded, and cross-correlations from linear envelope electromyography were calculated. RESULTS: The peak electromyogram showed large differences between the two applied loads and between subjects. There were time delays (75-165 msec) between the peak applied force and the peak electromyogram. The muscles on the contralateral side demonstrated different electromyographic profiles between subjects. Within subjects, the electromyographic profiles from each muscle were consistent for the same trial conditions. CONCLUSIONS: Electromyographic profiles and the cross-correlator coefficients for cervical muscles have shown reproducible intrasubject muscle synergies, which were not sensitive to the magnitude of applied load and the posture of the head. Intersubject muscle activity patterns varied.     

Anatomic considerations of anterior transarticular screw fixation for atlantoaxial instability

STUDY DESIGN: Anatomic parameters of C1 and C2 were measured in 30 dried human cervical spines. Anterior transarticular C1-C2 screws were placed in 15 cadaveric spines. OBJECTIVE: To provide anatomic data for anterior transarticular atlantoaxial screw or C1-C2 screw and plate fixation. SUMMARY OF BACKGROUND DATA: A posterior approach to fixation in the atlantoaxial joint has been well described. Damage to the vertebral artery is documented as a rare complication of posterior atlantoaxial transarticular screw fixation. An anterior surgical approach to exposing the upper cervical spine for internal fixation and bone graft recently has been developed. No anatomic information regarding the anterior transarticular atlantoaxial screw or screw and plate fixation between C1 and C2 is available in the literature. METHODS: Direct measurements using digital calipers and a goniometer were taken from 30 pairs of dried human C1 and C2 vertebrae. The anterior transarticular C1-C2 screw insertion point is at the junction of the lateral edge of the C2 vertebral body to 4 mm above the inferior edge of the C2 anterior arch. The parameters related to anterior transarticular atlantoaxial screw fixation or screw and plate fixation between the C1 lateral mass and the C2 vertebral body were measured. Fifteen embalmed cadavers were used for anterior C1-C2 transarticular screw placement. Longer screws (30-40 mm) were used to detect whether the screw tips violated the upper cervical canal or vertebral arteries. RESULTS: In the anterior transarticular atlantoaxial screw placement, lateral angulation of the screw placement relative to sagittal plane ranged from 4.8 +/- 1.8 degrees to 25.3 +/- 2.6 degrees. The posterior angulation of the screw placement relative to the coronal plane ranged from 12.8 +/- 3.1 degrees to 22.6 +/- 3.2 degrees. The length of the medial screw path ranged from 14.7 +/- 1.5 mm to 25.4 +/- 2.8 mm. In the anterior screw and plate fixation, the anteroposterior diameter of the inferior facet articular surface ranged from 16.2 +/- 1.6 mm to 17.1 +/- 1.8 mm. The anteroposterior diameter of the C2 vertebral body ranged from 9.3 +/- 1 mm to 16.2 +/- 1.8 mm. The anterior prevascular retropharyngeal approach appropriately exposed the atlantoaxial joint for anterior transarticular C1-C2 screw placement. No screws violated the vertebral artery and cervical canal. CONCLUSIONS: An anterior transarticular atlantoaxial screw 15-25 mm long can be inserted with a lateral angulation of 5-25 degrees relative to the sagittal plane and a posterior angulation of 10-25 degrees relative to the coronal plane. Additionally, in C1-C2 anterior plate fixation screws 15 mm long could be anchored in the inferior facet of the C1, and screws 9-15 mm long could be anchored in the C2 vertebral body.     

Reference structures for assessment of frontal head posture

The aim of the study was to test (a) the validity of the supra-orbital line as a substitute for the interpupillary line, and (b) the reproducibility of two different approaches of assessing cranio- and cervico-vertical relationships on frontal cephalograms. The material consisted of natural head position frontal cephalograms of 21 healthy Finnish students and 11 Danish young adults prepared according to a method described previously, modified in the Danish sample by addition of spectacles with a wire to indicate the interpupillary line. The cephalograms were analysed manually twice by two investigators with an interval of one week. The following reference lines were selected: (1) orbital line (ORB): a tangent to the extreme cranial point on the supra-orbital margins; (2) cranial line (CR): the line drawn through crista galli and anterior nasal spine; (3) cervical line (CER): a line drawn through the midpoints of atlas (half the distance between the most median points on the tubercle of the transverse ligament), and C4 (half the distance between the most concave points of the lateral masses); (4) the main course of the upper cervical spine (SPINE): a subjective impression of the spinal inclination; (5) the interpupillary line (IP); and (6) the true vertical and horizontal lines (VER, HOR). The angles were measured to the nearest 0.5 degrees. Intra- and inter-examiner reproducibility was calculated. The supra-orbital line almost coincided with the interpupillary line as the mean inclination between the lines was only 0.5 degrees. Both intra- and inter-examiner errors were less for ORB and CER than for CR and the line indicating the main course of the upper cervical spine (SPINE). The intra-examiner reproducibility s(i) for ORB/HOR and CR/VER was 0.4 and 0.8 degrees respectively, and for CER/VER and SPINE/VER 0.8 degrees and 1.0 degrees. Based on these results, the supra-orbital line and the cervical line (defined as the mid-transversal line between the atlas and the fourth cervical vertebra) are recommended as reference lines for assessing frontal head posture.     

Ultrasonographic assessment of bladder neck mobility in continent bitches and bitches with urinary incontinence attributable to urethral sphincter mechanism incompetence

OBJECTIVE: To determine bladder neck positional changes between standing and recumbent positions in bitches and whether change is related to continence status or general anesthesia, or both, and to evaluate reproducibility of measurements. ANIMALS: 45 continent animals and 46 incontinent bitches with urethral sphincter mechanism incompetence (SMI). PROCEDURE: Distance between the bladder neck and perineal skin was measured ultrasonographically via the perineum while each dog was conscious in standing and right lateral recumbency and in right lateral recumbency under general anesthesia. Measurements of the bladder neck position obtained in right lateral recumbency under anesthesia were compared with radiographic measurements of the same parameter. Reproducibility of the ultrasonographic measurements of the distance between bladder neck and perineum was assessed on 3 occasions for each position in 50 dogs. RESULTS: In all dogs, differences in bladder neck position between standing and recumbent conscious-associated positions were not significant. However, caudal bladder neck movement between standing conscious- and recumbent anesthesia-associated positions and between recumbent conscious- and anesthesia-associated positions was significant for all dogs. Incontinent bitches had greater degree of caudal bladder movement during anesthesia. Mean difference in bladder neck positions between recumbent conscious- and recumbent anesthesia-associated positions was 0.24 cm in continent, compared with 0.73 cm in incontinent, bitches. Radiographic measurements were significantly greater than ultrasonographic measurements. Differences between repeated measurements for standing position were not significant, but those for recumbent conscious- and recumbent anesthesia-associated positions were significant. CONCLUSIONS: Additional vesicourethral support mechanisms in continent dogs, are deficient in bitches with SMI, allowing the bladder neck to move further caudad.     

Introduction to the measurement of stress at work

OBJECTIVE: To determine the optimal postion for plate fixation in complex fractures of the proximal radius in which head and neck dissociation occurs. DESIGN: Technical study. SETTING: Tertiary referral center, teaching hospital, U.S. military. SUBJECTS: Five preserved cadavers. MAIN OUTCOME MEASURE: Radioulnar impingement and proximity to neurovascular structures were directly measured in elbows plated in each of three positions: neutral, full pronation, and full supination. RESULTS: Application of the 2.0-millimeter T-plate to the lateral aspect of the radial head and neck with the forearm in neutral position had no impingement, whereas application in full pronation resulted in loss of the last 30 degrees of supination. Plate application in full supination resulted in the loss of the last 10 degrees of pronation. In addition, there was no impingement when the 2.7-millimeter plate was applied similarily in the neutral position. None of these positions resulted in increased risk to neurovascular structures. CONCLUSIONS: The optimal position for plate fixation of complex proximal radius fractures is with the forearm in neutral position, with the plate applied directly lateral. A larger implant, 2.7 millimeters, may be used if this technique is followed without further risk of impingement and loss of motion.     

Posture in patients with shoulder overuse injuries and healthy individuals

Assessment of posture is an integral component of patient evaluation with shoulder overuse injuries. However, the professional literature contains relatively few studies that have assessed the relationship between posture, function, and injury. The purpose of this study was to determine the relationship and differences in postural variables within and between subjects with overuse injuries to the shoulder of healthy subjects. Thirty patient subjects and 30 healthy subjects matched for age and gender were recruited. Scapular protraction and rotation, forward head position, midthoracic curvature, and passive humeral elevation in the plane of the scapula were measured randomly in standing. All measurement techniques were standardized and validated. Intrarater and interrater reliability for all clinical measures were established before data collection. Forward head position was significantly greater (p < .001) in the patient group than the healthy group; humeral elevation was significantly greater (p < .001) in the healthy group than in the patient group and in the uninvolved shoulders (p < .01) than the involved shoulders within the patient group. Scapular protraction, rotation, midthoracic curvature, and scapular symmetry were not significantly different between groups. Scapula protraction and rotation were significantly related (p < .05) in the patient group. No other postural variables were related. Conclusions regarding the influence of posture to shoulder injury are inconclusive based on several confounding variables that may have affected the outcome.     

Lung mechanics in sitting and horizontal body positions

We measured lung compliance, pulmonary flow-resistance, and expiratory reserve volume (ERV) in ten healthy young adults in sitting, supine, and lateral positions. Average lung compliance was 0.21 in sitting, 0.19 in lateral and 0.16 L.cm H2O-1 in supine positions. The change was significant (p less than 0.01) between sitting and supine position. Flow-resistance increased from 1.78 in sitting to 2.5 cm H2O.L-1.s (p less than 0.001) in lateral positions, and did not increase further in the supine posture in spite of a 35 percent decrease in ERV (p less than 0.001). Since it is known that lower airways resistance increases with decreasing lung volume, the lack of change in flow-resistance when shifting from lateral to supine posture suggests that upper airways flow-resistance (larynx and oropharynx) is greater in the lateral decubitus than in the supine positions. The decrease of lung compliance in horizontal postures probably reflects increased pulmonary blood volume and small airways closure.