Lateral Head Position Research Articles

Ventilation quality and fiber optic glottic view of AuraGain laryngeal mask in neutral, moderate, and extreme lateral head and neck positions in anesthetized spontaneously breathing children

BackgroundWe investigated the effects of moderate (45°), and extreme (60°) right lateral rotation of the head and neck on the ventilatory performance of Ambu AuraGain Laryngeal mask airway in generally anesthetized spontaneously breathing children. MethodsFifty-two children (aged 2–9 years) were randomized in this open-label observational cohort, to receive Ambu® AuraGain either in moderate (45°) (Group I, n = 26) or extreme (60°) (Group II, n = 26) lateral rotation of the head and neck. The oropharyngeal leak pressure OLP (primary outcome), ventilation score, exhaled tidal volume, and fiberoptic glottic view score, were recorded with the head and neck in a neutral position, then in lateral position after insertion by 1,15,30 and 45 min., and at end of surgery. ResultsThe mean OLP in group I decreased from 23.81 ± 2.87 cmH2O in the neutral position to 23.77±3.78 cmH2O, (P = 0.941) 1 min. after lateral rotation. Whereas, In group II, it increased from 20.38 ± 4.18 cmH2O to 21.88±3.28 cmH2O, (P = 0.002). Afterward, the OLP was maintained decreased in group I and increased in group II (P < 0.05), with no intergroup differences. The ventilation score did not show significant intra or inter-group differences. After lateral rotation, the fiberoptic glottic score showed a trend towards better values in group II than in group I. ConclusionVentilation with AuraGain LMA can efficiently be implemented while the head and neck are in the neutral and laterally rotated positions in anesthetized spontaneously breathing children. Extreme lateral rotation (60°) was better tolerated than the moderate position (45°).

Evaluating Intraocular Pressure Alterations during Large Muscle Group Isometric Exercises with Varying Head and Body Positions.

Performing physical exercise affects intraocular pressure, and its elevation and fluctuations are the main risk factors for glaucoma development or progression. The aim of this study was to examine the acute alterations in intraocular pressure (IOP) during four unweighted isometric exercises and to determine whether the different head and body positions taken during exercise additionally affect IOP. Twelve healthy volunteers between the ages of 25 and 33 performed four isometric exercises: wall sit in neutral head and body position, elbow plank in prone head and body position, reverse plank in supine head and body position for 1 min, and right-side plank in lateral head and body position for 30 s. Intraocular pressure was measured by applanation portable tonometry, before performing the exercise, immediately after exercise completion, and after five minutes of rest. A significant acute increase in intraocular pressure was found as a response to the performance of the elbow plank (p < 0.01), the reverse plank (p < 0.001), and the right-side plank (p < 0.001). The wall sit exercise did not reveal a statistically significant IOP elevation (p = 0.232). Different head and body positions had no significant additional influence on IOP (F (3,33) = 0.611; p = 0.613), even though the alteration in IOP was found to be greater in exercises with a lower head and body position. Our data revealed that IOP elevation seems to be affected by the performance of the elbow plank, the reverse plank, and the right-side plank; and not by the wall sit exercise. More different isometric exercises should be examined to find ones that are safe to perform for glaucoma patients.

Exploring the Association Linking Head Position and Sleep Architecture to Motor Impairment in Parkinson's Disease: An Exploratory Study.

Patients with Parkinson's disease (PD) tend to sleep more frequently in the supine position and less often change head and body position during sleep. Besides sleep quality and continuity, head and body positions are crucial for glymphatic system (GS) activity. This pilot study evaluated sleep architecture and head position during each sleep stage in idiopathic PD patients without cognitive impairment, correlating sleep data to patients' motor and non-motor symptoms (NMS). All patients underwent the multi-night recordings, which were acquired using the Sleep Profiler headband. Sleep parameters, sleep time in each head position, and percentage of slow wave activity (SWA) in sleep, stage 3 of non-REM sleep (N3), and REM sleep in the supine position were extracted. Lastly, correlations with motor impairment and NMS were performed. Twenty PD patients (65.7 ± 8.6 y.o, ten women) were included. Sleep architecture did not change across the different nights of recording and showed the prevalence of sleep performed in the supine position. In addition, SWA and N3 were more frequently in the supine head position, and N3 in the supine decubitus correlated with REM sleep performed in the same position; this latter correlated with the disease duration (correlation coefficient = 0.48, p-value = 0.03) and motor impairment (correlation coefficient = 0.53, p-value = 0.02). These preliminary results demonstrated the importance of monitoring sleep in PD patients, supporting the need for preventive strategies in clinical practice for maintaining the lateral head position during the crucial sleep stages (SWA, N3, REM), essential for permitting the GS function and activity and ensuring brain health.

Cavernous Malformations: What They Have Taught Us.

Cavernous Malformations: What They Have Taught Us.

The effect of voluntary head movements on postural kinetics in the standing cat.

BackgroundAlthough the postural instability accompanying bilateral vestibular loss in human and quadrupeds during lateral head movements are well-known, it is still unclear whether or not lateral head turns would indeed activate the postural control system to maintain balance. This study aimed to examine the kinetic parameters in freely standing intact cats during head movements in order to further answer the above question.MethodsSix intact cats were trained to stand, unrestrained on a force plate and perform voluntary head movements to the left and right positions in response to visual cues. Each trial was divided into two phases, quiet standing with the cat’s head maintaining a straight forward and lateral head position after voluntary head movements. Kinetic parameters including peak pressure and contact area under each limb as well as center of pressure (COP) displacements of the whole body were measured.ResultsCompared to the neutral head position, peak pressure and contact area of the left head position were significantly smaller for the left forelimb while greatly larger for the right forelimb. An exact opposite case of peak pressure and contact area in the forelimbs was found between the right and neutral head positions. In addition, the COP displacements altered oppositely to the head movements, and presented a significantly right shift in the left position and a significantly left shift in the right position.ConclusionThese results demonstrate that the lateral displacement of the head in standing intact cats does activate the postural adjustment to maintain balance, which is consistent with the concept that vestibular input can contribute to postural balance during voluntary head turns.

Visual compensation in cervical dystonia

ABSTRACTIntroduction: Visual-spatial processing can be affected in people with cervical dystonia (CD). These impairments have almost exclusively been observed in laboratory studies, but the impact of visuo-spatial impairments on daily activities is unclear. Here, we investigated how people living with CD visually explore the environment.Method: 21 participants (10 patients and 11 controls) walked a designated course searching for targets while their eye movements were tracked by the means of eye tracking glasses. In addition, all participants performed an extensive battery of spatial neglect tests.Results: People with CD visually compensated for their lateral head position. That is, they made more eye movements towards the side opposite their lateral head position. No evidence for or against spatial asymmetries were detected in a range of behavioral measures (target detection, standard neglect battery tests) on a group level. Yet, single patients showed a neglect-like pattern. One patient with a right torticollis failed to detect most left-sided targets when walking.Conclusion: In general, participants seem to adequately compensate for the deviated head posture when judging spatial stimuli. However, the insufficient spatial exploration in one patient with a valid driving license should raise awareness in clinicians to potential visuo-spatial problems in people living with CD. An interesting question arising from our findings is whether people with CD and marked visuo-spatial deficits would benefit from scanning training, as is employed in stroke rehabilitation.

Floppy epiglottis during drug-induced sleep endoscopy: an almost complete resolution by adopting the lateral posture.

To analyze the presence of a floppy epiglottis (FE) during drug-induced sleep endoscopy in non-apneic snoring patients, non-positional obstructive sleep apnea (OSA) patients (NPP), and position-dependent OSA patients (PP) and to evaluate the impact of maneuvers and body position during drug-induced sleep endoscopy, including jaw thrust and supine and lateral head (and trunk) position. Retrospective cohort study. In total, 324 patients were included. In 60 patients (18.5%), a FE was found in supine position: seven non-apneic snoring patients and 53 OSA patients. When performing lateral head rotation only, a FE was present in four patients (NPP, N = 0; PP, N = 4). When patients were tilted to both lateral head and trunk position, a FE was found in only one subject. After applying jaw thrust, a FE was still present in 10 patients. The prevalence of a FE did not differ between NPP and PP. When comparing baseline characteristics between patients with and without a FE in supine position, no significant differences were found. A FE appears almost exclusively in supine position. In patients with a FE, positional therapy can be a promising alternative as a standalone treatment, but also as part of combination therapy with for example mandibular advancement devices or less invasive forms of upper airway surgery.

Automated Non-Contact Detection of Head and Body Positions During Sleep

Obstructive sleep apnea (OSA) is a respiratory disorder characterized by interruption to breathing during sleep. Usually, the OSA is more severe in the supine sleeping position. Recent studies also demonstrated that the head position may play an important role in the pathophysiology of the OSA. Therefore, monitoring the sleeping body and the head position has high clinical importance to optimize the treatment of the OSA. In this paper, three machine learning approaches were used to detect the head position during sleep in infrared images. In the first two methods, supervised classifiers were trained to estimate the head position based on different feature sets extracted from infrared images. In the third method, three different convolutional neural network (CNN) structures (ResNet50, MobileNet, and Darknet19) were trained to detect the head position during sleep. To detect the body position, the same CNN architectures were trained on infrared images. Overnight sleeping data (sleep duration =5±1h) from 50 participants (age: 53 ± 15 years, BMI: 29 ± 6 kg/m2, and 30 men/20 women) with various levels of OSA severity as measured by the apnea-hypopnea index (AHI =25±29 events/h and OSA severity: 12 normal, 13 mild, 11 moderate, and 14 severe) were collected for this paper. The models were trained on the data collected in one laboratory room from half of the participants and tested on the data from the other half collected in a different laboratory room. The best performing model (Darknet19) correctly estimated the lateral versus supine head position with 92% accuracy and 94% F1-Score and the lateral versus supine body position with 87% accuracy and 87% F1-Score.

French and English lexical blends in contrast

Abstract Two sets of 97 French and 374 English lexical units identified as lexical blends are examined from a contrastive perspective. It appears that English displays a wider variety of patterns than French does – a larger number of marginal types of lexical input combination, of lexical shortening and of phonological splitting. Striking dissimilarities between the two languages also include an inclination for the pattern of double inner shortening in English and the pattern of left-hand-side inner shortening in French, as well as a preference for semantic and phonological right-headedness in English and the absence of a preferred lateral head position in French.

Infrared-Based In-Vehicle Head Tracking: A Prototype for Tracking Drivers' Head Movements in Real Time

Future assistance systems in vehicles will require data that indicate the 3D position of the driver's head and eyes in real time. The head tracking is necessary, for example, so that information can be displayed in a contact-analog way, eventually increasing the driver's comfort and safety. For this, a study with 15 participants was conducted to examine typical driver head movements while driving. The study revealed overall only slight vertical and lateral head movements as well as little differing vertical and lateral head positions across different participants. A head tracking method based on these results was developed employing 2D to 3D conversion while using a single thermographic camera. Reducing the system to one camera cuts expenses significantly; however, doing so introduces small errors in the 3D detection. The choice was made in favor of thermal image processing since this allows the images to be treated independently of external light conditions, making the system reliable and suitable for nighttime driving.

Upper airway collapse during drug induced sleep endoscopy: head rotation in supine position compared with lateral head and trunk position

Drug induced sedated sleep endoscopy (DISE) is often employed to determine the site, severity and pattern of obstruction in patients with sleep apnea. DISE is usually performed in supine position. We recently showed that the obstruction pattern is different when DISE is performed in lateral position. In this study, we compared the outcomes of DISE performed in supine position with head rotated, with the outcomes of DISE performed with head and trunk in lateral position. The Prospective study design was used in the present study. Sixty patients with OSA (44 male; mean apnea hypopnea index (AHI) 20.8 ± 17.5 events/h) underwent DISE under propofol sedation. Patients were placed in lateral position, and the upper airway collapse was evaluated. The patients were then placed in supine position with the head rotated to the right side. DISE outcomes were scored using the VOTE classification system. In lateral position, nine patients (15.0%) had a complete antero-posterior (A-P) collapse at the level of the velum, nine had a partial A-P collapse. During head rotation and trunk in supine position, at the level of the velum, four patients (6.7%) had a complete A-P collapse, while two patients (3.3%) had a partial A-P collapse. For all other sites, the patterns of collapse were not significantly different between head rotation and lateral position. During DISE, rotation of the head in supine position, and lateral head and trunk position present similar sites, severity and patterns of upper airway collapse, with the exception of collapse at the level of the velum. Here the severity of A-P collapse is less severe during head rotation than in lateral head and trunk position.

Sleeping posture and intraocular pressure

This prospective observational case series aimed to determine whether the lateral decubitus position, which is commonly adopted during sleep, has an effect on intraocular pressure (IOP) in normal controls. Patients without glaucoma were recruited from those visiting outpatient clinics for non-glaucomatous conditions. The left eye of each patient was included. IOP was first measured using Tono-Pen® XL applanation tonometer in the supine position, following which a second measurement was immediately obtained for the left lateral head position. Measurements were obtained with the patient lying on one soft and one hard pillow for each position, and patients remained awake during these measurements. One tonometry reading was obtained for each position. Readings were recorded only when the average of four independent readings produced a statistical confidence index of 5%. Results were analysed using the paired Student's t-test for comparison of the means. IOP in the left lateral decubitus position (17.48 ± 3.18 mmHg) was significantly higher than in the supine position (14.48 ± 3.09 mmHg) when using soft pillows (p < 0.001). When hard pillows were used, IOP in the left lateral decubitus position also exceeded that measured in the supine position (16.65 ± 3.54 mmHg vs. 13.65 ± 3.58 mmHg; p < 0.001). There was no statistically significant difference in the IOPs measured for the same position when different kinds of pillows were used. The lateral decubitus position adopted during sleep is associated with changes in IOP in healthy volunteers.

The effect of lateral head position on sleep disordered breathing: A case series

The effect of lateral head position on sleep disordered breathing: A case series

Correlation between the head‐lying side during sleep and the affected side by benign paroxysmal positional vertigo involving the posterior or horizontal semicircular canal

The aim of this study was to evaluate the relationship between the head position during sleep and the affected semicircular canal (SCC) in patients with benign paroxysmal positional vertigo (BPPV). Prospective study at a tertiary hospital. We conducted a prospective study in patients with BPPV involving posterior or horizontal SCCs. Of a total of 425 patients diagnosed with BPPV, 83 patients showing signs of simultaneous multiple canal involvement, and those having combined otologic diseases in the same ear were excluded from the study. All patients included in the study were asked to define their preferred head-lying side at the beginning of sleep among the following choices: supine, lateral (right or left), or no predominant side. Our study included 174 patients with posterior SCC BPPV (p-BPPV) and 168 patients with horizontal SCC BPPV (h-BPPV). Patients habitually adopted a lateral head position during sleep in 105 cases of p-BPPV and 109 cases of h-BPPV. Statistically significant correlation was demonstrated between the head-lying side during sleep and the affected side by BPPV (P < .01) in patients with p-BPPV as well as h-BPPV. There is significant correlation between the head-lying side during sleep and the side affected by BPPV in h-BPPV and p-BPPV, which may provide additional clues about the pathophysiology of BPPV. Clinically, this information may be used to provide helpful guidelines for patients with BPPV concerning their sleeping positions to prevent recurrence of BPPV.

1175 Pilot Randomized Study on the Risk of Intraventricular Hemorrhage with Midline Versus Lateral Head Positions

Objective: To study a hypothesis that keeping preterm infants' heads in midline positions reduces their risk of intraventricular hemorrhage (IVH). Methods: We conducted a pilot randomized trial to study this hypothesis by comparing the IVH risk associated with flat midline (FM) and flat lateral (FL) head positions throughout the first seven days of life. Randomization was stratified based on gender and gestational age (< 27 or 27-29.9 weeks). Results: Twenty-three infants younger than 30 weeks gestation were randomly assigned to the FM group, and 21 infants of similar age were assigned to the FL group (right-tilted: n = 9; left-tilted: n = 12). Important baseline characteristics were similar in both groups, except for multiple births which were significantly higher in the FM group. The risk of IVH was higher in the FM group than in the FL group (6 vs. 4; risk ratio (RR) 1.4; 95% confidence interval (CI): 0.4-4.2; p = 0.8). A secondary analysis showed that the risk of IVH was two times higher in the FM group than in the right-tilted FL group (6 vs. 1; RR 2.3; 95% CI: 0.3-16.9; p = 0.6) and was the same in the FM and left-tilted FL groups (6 vs. 3; RR 1.0; 95% CI: 0.3-3.5; p >0.99). Conclusions: Keeping a preterm infant's head in the FM position throughout the first seven days of life does not decrease the risk of IVH; however, a right-tilted FL position may reduce this risk. A larger study is needed for a definitive conclusion.

Positional nystagmus reversing from geotropic to apogeotropic: a new central vestibular syndrome

Central positional paroxysmal vertigo (CPPV) is rarely encountered in clinical practice. It must be distinguished from the more frequent benign positional paroxysmal vertigo (BPPV) [1, 2] and only an accurate clinical evaluation can identify it. Mostly, CPPV is due to cerebellar disease from various aetiologies, including neoplasm, as in the case reported here [3–5]. In this patient, clinical examination with video-oculography revealed right beating horizontal nystagmus in the right lateral head position (geotropic nystagmus) that reversed direction (to apogeotropic nystagmus) while the head position was maintained. In the left lateral position, the patient had again geotropic nystagmus reversing to apogeotropic nystagmus. Brain imaging revealed the presence of a right hemisphere cerebellar neoplasm causing compression of the IV ventricle and hence the vestibular disturbance. A 50-year-old female patient was referred to our neurootology service because of imbalance and vertigo subacutely developed a fortnight earlier. She had a history of breast cancer treated with surgery in May 1997, followed by adjuvant chemotherapy and hormone therapy. Neurological examination revealed a retropulsion in Romberg position and a backward displacement on the Fukuda stepping test. Coordination was only mildly impaired, with limb dysmetria on right finger-to-nose test. Cranial nerves were intact. Tendon reflexes were symmetrical with flexor plantar responses. Video-oculography showed no spontaneous nystagmus in primary position and no gaze-evoked nystagmus was revealed. Head-shaking test was normal. A slight delay was observed on the horizontal head impulse test toward the right side. Upon slowly positioning the patient in the right lateral head position, first-phase nystagmus manifested itself as right beating paroxysmal nystagmus (geotropic) without any latency. It gradually diminished, only to reverse its direction after about 10 s with the development of left beating (apogeotropic) second-phase nystagmus, as shown in the video (Online resource 1). On the left side, a similar, although less intense, geotropic nystagmus was observed. It reversed its direction in about 20 s, changing to apogeotropic nystagmus, as shown in the video (Online resource 2). Recording of the nystagmus activity revealed a maximal slow-phase velocity (SPV) of 19.6 /s for right geotropic nystagmus, while on the left side it showed an SPV of 8.6 /s. First-phase nystagmus was more intense both on the right and left sides, although it didn’t last as long as secondary apogeotropic nystagmus (Fig. 1). When tested in the straight head-hanging position, no nystagmus was detected. Electronic supplementary material The online version of this article (doi:10.1007/s00415-010-5701-6) contains supplementary material, which is available to authorized users.

Posture of the arm when grasping spheres to place them elsewhere

Despite the infinitely many ways to grasp a spherical object, regularities have been observed in the posture of the arm and the grasp orientation. In the present study, we set out to determine the factors that predict the grasp orientation and the final joint angles of reach-to-grasp movements. Subjects made reach-to-grasp movements toward a sphere to pick it up and place it at an indicated location. We varied the position of the sphere and the starting and placing positions. Multiple regression analysis showed that the sphere’s azimuth from the subject was the best predictor of grasp orientation, although there were also smaller but reliable contributions of distance, starting position, and perhaps even placing position. The sphere’s initial distance from the subject was the best predictor of the final elbow angle and shoulder elevation. A combination of the sphere’s azimuth and distance from the subject was required to predict shoulder angle, trunk-head rotation, and lateral head position. The starting position best predicted the final wrist angle and sagittal head position. We conclude that the final posture of the arm when grasping a sphere to place it elsewhere is determined to a larger extend by the initial position of the object than by effects of starting and placing position.

Tribology and Wear of Metal-on-Metal Hip Prostheses: Influence of Cup Angle and Head Position

Clinical studies have indicated that the angular position of the acetabular cup may influence wear in metal-on-metal total hip bearings. A high cup angle in comparison to the anatomical position may lead to the head being constrained by the superior lateral surface and rim of the cup, thus potentially changing the location of the contact zone between the head and the cup. The aim of this study was to test the hypothesis that both a steep cup angle and a lateralized position of the head can increase head contact on the superior rim of the cup, with the consequence of increased wear. Hip-joint simulator studies of metal-on-metal bearings were undertaken with cup angles of 45 degrees and 55 degrees . The femoral head was either aligned to the center of the cup or placed in a position of microlateralization. Wear was measured gravimetrically over 5 million cycles. A steep cup angle of 55 degrees showed significantly higher long-term steady-state wear than a standard cup angle of 45 degrees (p < 0.01). The difference was fivefold. Microlateralization of the head resulted in a fivefold increase in steady-state wear compared with a centralized head. The combination of a steep cup angle and a microlateralized head increased the steady-state wear rate by tenfold compared with a standard cup angle with a centralized head. These studies support the hypothesis that both an increased cup angle and a lateral head position increase wear in metal-on-metal hip prostheses.

Effect of head rotation on vascular anatomy of the neck: An ultrasound study

Abstract Carotid artery injury is a serious complication of landmark-guided internal jugular catheterization. Studies have determined that the internal jugular vein (IJV) frequently overlaps the carotid artery (CA), which has been postulated to increase the rate of arterial injury. The purpose of this study was to define the anatomic relationship of the IJV and CA by describing CA overlap by the more superficial IJV. We also seek to determine the effect of head rotation on the amount of overlap, which may have implications for IJV catheter placement. We prospectively studied the vascular anatomy of the neck in 156 Emergency Department patients. The primary intervention was head rotation to the left, as if the patient was positioned for right IJV catheterization. The patient’s head was positioned at 0, 45 and 90 degrees of rotation. Ultrasound images were obtained in a transverse orientation. The percentage overlap of the CA by the IJV was measured. We also measured the distance between the jugular vein and the carotid artery. In neutral position, there was a mean overlap of 29% at the apex of the sternocleidomastoid. As the head was turned, the percent overlap increased. At 90 degrees, there was a mean overlap of 72%. Differences were determined to be significant by analysis of variance (ANOVA) with a p < 0.001. Furthermore, we found a distance of 10 mm between IJV and CA when the head is in neutral position. As the head was turned, the jugular-carotid distance decreased to 1 mm in the far lateral head position. These differences were also found to be significant by ANOVA with a p < 0.001. We concluded that the IJV overlaps the CA in the neutral position to a significant degree. This overlap increases until the head is fully turned, where most of the CA is overlapped by the IJV. This may help explain the mechanism of CA puncture. We propose two modifications to standard IJV line technique: minimize the patients’ head rotation; and use ultrasound guidance for IJV catheterization.

Influence of anatomy and head position on intranasal drug deposition

The objective of this study was to determine the influence of individual anatomical differences on intranasal drug deposition. The data of a comparison of seven different administration techniques in ten healthy volunteers was used in this single-blind crossover pilot study. After intranasal administration of a dyed test formulation, endoscopic video imaging was done on seven non-sequential days. The deposition pattern per individual around the head of the middle turbinate was analyzed for each technique and correlated with the individual anatomy. Decreased deposition of dyed test formulation in the target area around the head of the middle turbinate was observed in the presence of minor septal deviations, narrow nasal valve areas, or inferior turbinate hypertrophy; a lateral head position helps to bypass a minor septal deviation. Although results are preliminary, we conclude that anatomy and head position are important factors in the deposition of topical nasal drugs and may be the key to improving individual local nasal (steroid) treatment.