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Head Position (head + position)
Kinds of Head Position Selected AbstractsNocebo as headache trigger: evidence from a sham-controlled provocation study with RF fieldsACTA NEUROLOGICA SCANDINAVICA, Issue 2008L. J. Stovner Background ,, A large proportion of the population in Norway has experienced headache in connection with mobile phone use, but several double-blind provocation studies with radiofrequency (RF) and sham exposures have shown no relation between headache and mobile phone RF fields. Aims ,, To investigate the type and location of headache experienced by participants in one provocation study in order to gain insight into possible causes and mechanisms of the headaches. Method ,, Questionnaire about headache, indication on figure of location of headache after exposure, interview with neurologist about headache features to make headache diagnoses. Results ,, The 17 participants went through 130 trials (sham or RF exposure). No significant difference existed in headache type, laterality or location between the headaches experienced with the two exposures types. In most participants, the headache was compatible with tension-type headache. Discussion ,, As participants experienced their typical ,mobile phone headache' both with and without RF exposure, and since the experiment did not involve the stress or the arm/head position of mobile phone use, the most likely explanation is that the headache in this situation is caused by negative expectations (nocebo). Conclusion ,, This and other similar studies indicate that headache occurring in connection with mobile phone use is not related to RF fields, and that a nocebo effect is important for this and possibly other headache triggers. [source] Fetal handedness and head position preference: A developmental studyDEVELOPMENTAL PSYCHOBIOLOGY, Issue 3 2001J.I.P. de Vries Abstract Hand,head contacts were observed by means of serial ultrasound recordings in 10 healthy fetuses from 12 to 38 weeks of gestational age. Contacts were distinguished as being unimanual or bimanual, and if unimanual, whether they were made with the right or left hand. Both types of contact and ones made unimanually with the right or left hand were identified at each age as to whether they were associated with a preferential head position. A strong unimanual bias was evident at each age except for Week 36. At this age, there was a bimanual bias. Unimanual contacts did not develop a lateralized preference, and neither type of contact established a stable relationship with head position. Furthermore, there was no evidence to support the suggestion that hand contact and head position codevelop to form a preferred ipsilateral synergy. Findings are discussed relative to contradictory evidence from other fetal and neonatal studies. © 2001 John Wiley & Sons, Inc. Dev Psychobiol 39: 171,178, 2001 [source] Channel head location and characteristics using digital elevation modelsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 7 2006G. R. Hancock Abstract The drainage network is the conduit through which much surface water and sediment are routed within a catchment. In a catchment, the position of where hillslopes begin and channels end has long been considered the position of transition between diffusive processes upslope and the more incisive fluvial processes downslope. Consequently, understanding channel head location is an important issue in understanding catchment hydrology and geomorphology. This study examines channel head position and characteristics in a catchment in Arnhem Land, Northern Territory, Australia. In this study the position of channel heads was mapped within the catchment and plotted on a reliable digital elevation model of the catchment. It was found that the majority of channel heads have relatively small source areas and that graphical catchment descriptors, such as the area,slope relationship and cumulative area distribution, can provide reliable measures of the field position of the heads of first-order streams and the transition from hillslope to channel. The area,slope relationship and cumulative area distribution are also shown to be good tools for determining digital elevation model grid size which can capture hillslope detail and the transition from hillslope to channel. Copyright © 2005 John Wiley & Sons, Ltd. [source] The influence of head and neck position on kinematics of the back in riding horses at the walk and trotEQUINE VETERINARY JOURNAL, Issue 1 2005M. RHODIN Summary Reasons for performing study: A common opinion among riders and in the literature is that the positioning of the head and neck influences the back of the horse, but this has not yet been measured objectively. Objectives: To evaluate the effect of head and neck position on the kinematics of the back in riding horses. Methods: Eight Warmblood riding horses in regular work were studied on a treadmill at walk and trot with the head and neck in 3 different predetermined positions achieved by side reins attached to the bit and to an anticast roller. The 3-dimensional movement of the thoracolumbar spine was measured from the position of skin-fixed markers recorded by infrared videocameras. Results: Head and neck position influenced the movements of the back, especially at the walk. When the head was fixed in a high position at the walk, the flexion-extension movement and lateral bending of the lumbar back, as well as the axial rotation, were significantly reduced when compared to movements with the head free or in a low position. At walk, head and neck position also significantly influenced stride length, which was shortest with the head in a high position. At trot, the stride length was independent of head position. Conclusions: Restricting and restraining the position and movement of the head and neck alters the movement of the back and stride characteristics. With the head and neck in a high position stride length and flexion and extension of the caudal back were significantly reduced. Potential relevance: Use of side reins in training and rehabilitation programmes should be used with an understanding of the possible effects on the horse's back. [source] Measurement of respiratory function by impulse oscillometry in horsesEQUINE VETERINARY JOURNAL, Issue 1 2004E. Van Erck Reasons for performing study: Due to technical implementations and lack of sensitivity, pulmonary function tests are seldom used in clinical practice. Impulse oscillometry (IOS) could represent an alternative method. Objectives: To define feasibility, methodology and repeatability of IOS, a forced oscillation technique that measures respiratory resistance (Rrs) and reactance (Xrs) from 5 to 35 Hz during spontaneous breathing, in horses. Methods: Using 38 healthy horses, Rrs and Xrs reference values were defined and influence of individual biometrical parameters was investigated. In addition, IOS measurements of 6 horses showing clinical signs of heaves were compared to those of 6 healthy horses. Results: Airtightness and minimal dead space in the facemask were prerequisites to IOS testing and standardisation of head position was necessary to avoid variations in Rrs due to modified upper airway geometry. In both healthy and diseased animals, measurements were repeatable. In standard-type breeds, the influence of the horse's size on IOS parameters was negligible. An increase in R5Hz greater than 0.10 kPa/l/sec and R5Hz>R10Hz, combined with negative values of Xrs between 5 and 20 Hz, was indicative of heaves crisis. Conclusions: IOS is a quick, minimally invasive and informative method for pulmonary function testing in healthy and diseased horses. Potential relevance: IOS is a promising method for routine and/or field respiratory clinical testing in the equine species. [source] Confusion Effect in a Reptilian and a Primate PredatorETHOLOGY, Issue 8 2000Carsten Schradin The confusion effect is claimed to be one benefit of group living with respect to predator avoidance: it is more difficult for predators to capture prey that is surrounded by other conspecifics than to capture an isolated individual. So far, the predictions of the confusion effect have been tested mainly in aquatic predators. As the confusion effect is seen to be a general problem for predators, terrestrial predators of two different vertebrate classes were used to test it. The prey (mealworms and black beetles, Tenebrio molitor) was harmless and had no chance of predator avoidance. Thus, confounding effects of group defence and enhanced vigilance were controlled. Both leopard geckos (Eublepharis macularius) and common marmosets (Callithrix jacchus) took longer to catch one out of several prey compared to one single prey. Leopard geckos showed more fixations (changing of head position) when confronted with 20 mealworms than when confronted with only one mealworm, thus showing indications of being ,confused'. [source] Electromyographic evaluation of cervical dystonia for planning of botulinum toxin therapyEUROPEAN JOURNAL OF NEUROLOGY, Issue 6 2000D. Dressler The success of botulinum toxin (BT) injections for treatment of cervical dystonia depends on precise identification of dystonic muscles and on quantification of their dystonic involvement. Conventionally, this is attempted by clinical examination analysing the dystonic head position. In this presentation, a more systematic approach is sought by using an electromyography (EMG)-based evaluation procedure. In 10 consecutive patients with cervical dystonia not previously exposed to BT clinical examination, analysing the dystonic head position was performed to classify patients into four groups with similar dystonic head positions. Additionally, a 2-channel concentric needle EMG was used to measure the amplitudes of dystonic and maximal voluntary activities in sternocleidomastoid (SCM), splenius capitis (SC) and trapezius/semispinalis capitis (T/SS) muscles bilaterally. The ratio between both amplitudes, the dystonia ratio, was used to quantify dystonic muscle involvement. In all patients dystonia ratios could be calculated. In patients with similar head positions, EMG evaluation revealed different qualitative and quantitative dystonic involvement patterns. In six patients, there were discrepancies in identification of dystonic muscles between clinical examination and EMG evaluation. EMG evaluation excluded dystonic involvement in five patients. All excluded muscles were SCM. In one of these patients, additional T/SS involvement was detected by EMG evaluation. In one patient, SC involvement was revealed by EMG evaluation. All dystonic muscle involvement detected by EMG evaluation represented genuine dystonic muscle coactivation rather than compensatory muscle activity. The EMG evaluation presented allows quantitative and qualitative identification of dystonic muscle involvement which cannot be achieved by clinical examination. Both pieces of information may be helpful for optimization of BT therapy. [source] Simultaneously recorded EEG,fMRI: Removal of gradient artifacts by subtraction of head movement related average artifact waveformsHUMAN BRAIN MAPPING, Issue 10 2009Limin Sun Abstract Electroencephalograms (EEGs) recorded simultaneously with functional magnetic resonance imaging (fMRI) are corrupted by large repetitive artifacts generated by the switched MR gradients. Several methods have been proposed to remove these distortions by subtraction of averaged artifact templates from the ongoing EEG. Here, we present a modification of this approach which accounts for head movements to improve the extracted template. Using the fMRI analysis package statistical parametric mapping (SPM; FIL London) the head displacement is determined at each half fMRI-volume. The basic idea is to apply a moving average algorithm for template extraction but to include only epochs that were obtained at the same head position as the artefact to be removed. This approach was derived from phantom EEG measurements demonstrating substantial variations of the artefact waveform in response to movements of the phantom in the MRI magnet. To further reduce the residual noise, we applied a resampling algorithm which aligns the EEG samples in a strict adaptive manner to the fMRI timing. Finally, we propose a new algorithm to suppress residual artifacts such as those occasionally observed in case of brief strong movements, which are not reflected by the movement indicator because of the limited temporal resolution of the fMRI sequence. On the basis of EEG recordings of six subjects these measures combined reduce the residual artefact activity quantified in terms of the spectral power at the gradient repetition rate and its harmonics by roughly 20 to 50% (depending on the amount of movement) predominantly in frequencies beyond 30 Hz. Hum Brain Mapp, 2009. © 2009 Wiley-Liss, Inc. [source] Relation between cervical posture on lateral skull radiographs and electromyographic activity of masticatory muscles in caucasian adult women: a cross-sectional studyJOURNAL OF ORAL REHABILITATION, Issue 9 2007S. TECCO Summary, The aim of this study was to evaluate the association between cervical posture on lateral skull radiographs and surface electromyographic recordings (sEMG) of head and neck muscles. The sample comprised 40 Caucasian adult females, average age 26·8 (20,48); lateral skull radiographs were obtained in natural head position (mirror position). sEMG activity was bilaterally investigated for the following muscles: masseter, anterior temporalis, digastric, posterior cervical, sternocleidomastoid and upper and lower trapezius. All muscles were monitored at rest and during maximal voluntary clenching (MVC). A Pearson's correlation coefficient revealed significant correlations (P < 0·01) between cranio-cervical angulations and sEMG activity of masseter, digastric, lower trapezius, during MVC and anterior temporalis at rest. Significant correlations (P < 0·01) were also found between cervical lordosis angle and sEMG activity of masseter (during MVC) and lower trapezius (at rest). In view of transversal method, no conclusion was possible about the mechanism concerning these results. Future longitudinal studies should be directed to understand the extent of environmental and genotype influences by masticatory muscle activity on cervical posture. [source] Intranasal delivery to the central nervous system: Mechanisms and experimental considerationsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 4 2010Shyeilla V. Dhuria Abstract The blood,brain barrier (BBB) limits the distribution of systemically administered therapeutics to the central nervous system (CNS), posing a significant challenge to drug development efforts to treat neurological and psychiatric diseases and disorders. Intranasal delivery is a noninvasive and convenient method that rapidly targets therapeutics to the CNS, bypassing the BBB and minimizing systemic exposure. This review focuses on the current understanding of the mechanisms underlying intranasal delivery to the CNS, with a discussion of pathways from the nasal cavity to the CNS involving the olfactory and trigeminal nerves, the vasculature, the cerebrospinal fluid, and the lymphatic system. In addition to the properties of the therapeutic, deposition of the drug formulation within the nasal passages and composition of the formulation can influence the pathway a therapeutic follows into the CNS after intranasal administration. Experimental factors, such as head position, volume, and method of administration, and formulation parameters, such as pH, osmolarity, or inclusion of permeation enhancers or mucoadhesives, can influence formulation deposition within the nasal passages and pathways followed into the CNS. Significant research will be required to develop and improve current intranasal treatments and careful consideration should be given to the factors discussed in this review. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 1654,1673, 2010 [source] Complex mechanisms of sensory tricks in cervical dystoniaMOVEMENT DISORDERS, Issue 4 2004Axel Schramm MD Abstract Muscle activities in 26 patients with predominantly rotational torticollis were quantified using surface electromyography. In the subgroup of 19 patients with an effective sensory trick, different modes and bilateral locations of trick application led to significant (P < 0.002) reduction of electromyographic (EMG) activity. A strong correlation was found between the efficacy of trick manoeuvres and the starting head position. Trick application in a neutral or even contralateral position was most effective while no reduction of muscle activity during trick application at the maximum dystonic head position was found (P < 0.001). We propose a two-phase model: First, normalisation of head posture is obtained by counterpressure or volitional antagonistic muscle activity. In a second step, this position can be stabilised using sensory tricks challenging central adaption of distorted sensorimotor integration. © 2003 Movement Disorder Society [source] Automated assessment of cervical dystoniaMOVEMENT DISORDERS, Issue 11 2003Giuseppe Galardi MD Abstract We developed an automated and objective method to measure posture and voluntary movements in patients with cervical dystonia using Fastrack, an electromagnetic system consisting of a stationary transmitter station and four sensors. The junction lines between the sensors attached to the head produced geometrical figures on which the corresponding aspects of the head were superimposed. The head position in the space was reconstructed and observed from axial, sagittal, and coronal planes. Four patients with cervical dystonia and 6 healthy subjects were studied. Each patient was representative of one of the typical patterns of cervical dystonia. The study allowed the authors to collect quantitative data on posture and range of motion of the head. This pilot study demonstrates the efficacy of the Fastrack system to objectively measure the head position in cervical dystonia patients. © 2003 Movement Disorder Society [source] Spontaneously changing muscular activation pattern in patients with cervical dystoniaMOVEMENT DISORDERS, Issue 6 2001A. Münchau MD Abstract The objective of this study was to determine stability of the neck muscle activation pattern in a given dystonic head position in patients with cervical dystonia (CD). We assessed 26 patients with CD and botulinum toxin (BT) treatment failure before surgical denervation. None of them had received BT injections for at least 4 months. To relate dystonic head position to underlying neck muscle activity, we used synchronised video and poly-electromyographic (EMG) recording over a period of 10 minutes. The muscle activation pattern during constant ("stable") maximal dystonic excursions was analysed. EMG data of nine patients was excluded from the analysis, as these patients had a constantly changing head position or marked head tremor. In the remaining 17 patients, who had a fairly stable dystonic position, muscular activation patterns during the recording spontaneously changed in nine (Group A) while in eight it remained stable (Group B). There was no significant difference in demographic variables between the two groups other than a male predominance in Group A. However, the retrospectively determined initial response to BT treatment (before BT treatment failure had occurred) was significantly worse in Group A as compared with Group B. Neck muscle activation patterns can spontaneously change in CD patients despite constant dystonic head position, implying an inherent variability of the underlying central motor program in some patients. This should be considered when BT treatment response is unsatisfactory, and should also be taken into account when interpreting results of EMG recordings of neck muscles in these patients. © 2001 Movement Disorder Society. [source] Nothing to sneeze at!ANZ JOURNAL OF SURGERY, Issue 12 2009A study into intra-operative contamination Abstract Purpose:, We performed a prospective study of sneezes from orthopaedic registrars to assess the potential for intra-operative contamination from a masked surgeon, and to determine if head position can alter the potential for contamination. Type of Study:, Prospective controlled trial. Methods:, Four orthopaedic registrars from the Gold Coast Hospital each inhaled pepper to precipitate a sneeze. Cultures were taken with and without standard Smith & NephewÔ surgical masks, in positions directly in front and to the sides of a masked registrar. The process was repeated three times for each registrar. A control plate was left exposed to the atmosphere. A control plate and sneeze plate was cultured on blood agar. Three masks were subsequently swabbed to exclude contamination from the masks. Results:, 2/24 (8.33%) of the side with mask cultures returned significant bacterial growths. Also, 1/12 (8.33%) of the front with mask cultures returned significant growths. In addition, 9/12 (75%) of the direct sneezes resulted in significant bacterial counts. The control plate failed to return any growth. Subsequent culture of the exterior of three surgical masks failed to yield significant growth. There was a statistically significant odds ratio of 0.03 comparing the front and side group with the unmasked direct group. There was no statistically significant difference comparing front and side sneeze growth. Conclusions:, While the use of surgical face masks significantly reduces bacterial counts following a sneeze, it fails to eliminate the potential for surgical field contamination completely. The fact that significant bacterial counts can be returned from direct culture through a mask and to the sides of a mask suggests that head position is irrelevant and contamination is possible in any direction. It is, therefore, suggested that, if possible, a sneezing surgeon distances himself/herself as much as possible from the sterile field. We also recommend following a sneeze; surgeons should re-gown and glove, given the risk of contamination of the sterile field. Level of evidence:, Level II. [source] Maternal thyroid hormone concentration during late gestation is associated with foetal position at birthCLINICAL ENDOCRINOLOGY, Issue 5 2009Hennie A. Wijnen Summary Objective, To evaluate whether there is an association between maternal thyroid hormone and foetal cephalic head position at term gestation. Context, Rotation and flexion of the head enables the foetus to negotiate the birth canal. Low-normal range thyroid hormone concentrations in euthyroid pregnant women constitute a risk of infant motor abnormality. We hypothesized that low normal maternal thyroid hormone levels are associated with increased risk of abnormal foetal position at delivery. Design, In 960 healthy Dutch women with term gestation and cephalic foetal presentation, thyroid parameters [foetal T4 (FT4), TSH and thyroid peroxidase antibody] were assessed at 36 weeks of gestation, and related to foetal head position (anterior cephalic vs. abnormal cephalic) and delivery mode (spontaneous vs. assisted delivery). Results, Women presenting in anterior position (n = 891) had significantly higher FT4 levels at 36 weeks of gestation than those with abnormal cephalic presentation (n = 69). There were no between-group differences for TSH. Regression analyses indicated that the risk of abnormal head position decreased as a function of increasing FT4 [single odds ratio (OR) = 0·87, 95% confidence intervals (CI) 0·77,0·98; multivariate OR = 0·88, 95% CI 0·72,0·99)]. A similar inverse relationship between maternal FT4 and risk of assisted delivery was obtained (OR = 0·86, 95% CI 0·79,0·95; OR = 0·91, 95% CI 0·84,0·98). Conclusion, The lower the maternal FT4 concentration at 36 weeks of gestation, the higher the risk of abnormal cephalic foetal presentation and assisted delivery. [source] Women as Policy Makers: Evidence from a Randomized Policy Experiment in IndiaECONOMETRICA, Issue 5 2004Raghabendra Chattopadhyay This paper uses political reservations for women in India to study the impact of women's leadership on policy decisions. Since the mid-1990's, one third of Village Council head positions in India have been randomly reserved for a woman: In these councils only women could be elected to the position of head. Village Councils are responsible for the provision of many local public goods in rural areas. Using a dataset we collected on 265 Village Councils in West Bengal and Rajasthan, we compare the type of public goods provided in reserved and unreserved Village Councils. We show that the reservation of a council seat affects the types of public goods provided. Specifically, leaders invest more in infrastructure that is directly relevant to the needs of their own genders. [source] Electromyographic evaluation of cervical dystonia for planning of botulinum toxin therapyEUROPEAN JOURNAL OF NEUROLOGY, Issue 6 2000D. Dressler The success of botulinum toxin (BT) injections for treatment of cervical dystonia depends on precise identification of dystonic muscles and on quantification of their dystonic involvement. Conventionally, this is attempted by clinical examination analysing the dystonic head position. In this presentation, a more systematic approach is sought by using an electromyography (EMG)-based evaluation procedure. In 10 consecutive patients with cervical dystonia not previously exposed to BT clinical examination, analysing the dystonic head position was performed to classify patients into four groups with similar dystonic head positions. Additionally, a 2-channel concentric needle EMG was used to measure the amplitudes of dystonic and maximal voluntary activities in sternocleidomastoid (SCM), splenius capitis (SC) and trapezius/semispinalis capitis (T/SS) muscles bilaterally. The ratio between both amplitudes, the dystonia ratio, was used to quantify dystonic muscle involvement. In all patients dystonia ratios could be calculated. In patients with similar head positions, EMG evaluation revealed different qualitative and quantitative dystonic involvement patterns. In six patients, there were discrepancies in identification of dystonic muscles between clinical examination and EMG evaluation. EMG evaluation excluded dystonic involvement in five patients. All excluded muscles were SCM. In one of these patients, additional T/SS involvement was detected by EMG evaluation. In one patient, SC involvement was revealed by EMG evaluation. All dystonic muscle involvement detected by EMG evaluation represented genuine dystonic muscle coactivation rather than compensatory muscle activity. The EMG evaluation presented allows quantitative and qualitative identification of dystonic muscle involvement which cannot be achieved by clinical examination. Both pieces of information may be helpful for optimization of BT therapy. [source] Relationship between ease of swallowing and deglutition-related muscle activity in various posturesJOURNAL OF ORAL REHABILITATION, Issue 8 2010T. SAKUMA Summary, The purpose of this study was to investigate the relationship between the ease of swallowing and the deglutition-related muscle activity in various body and head postures by surface electromyography (EMG). Bipolar surface electrodes were placed on the right suprahyoid and infrahyoid muscles of nine healthy adults (19,28 years) while swallowing jelly. Ten postures per subject were examined: five body angulations (0° [supine], 30°, 60°, 90° [upright] and 120° from the horizontal) and two head positions (chin-up and chin-down). The duration and amplitude of suprahyoid and infrahyoid muscle activity were measured by an electromyograph, and the ease of swallowing was subjectively determined by using a rating scale (0 = difficult to swallow, 10 = easy to swallow). The group-average duration and amplitude of muscle activity and the group-average rating scales mostly showed insignificant changes with the body angulations independent of the head positions. Interestingly, the duration and amplitude of muscle activity during swallowing were negatively correlated with the rating scales, indicating that a shorter duration and smaller activity of muscle activity corresponds to easier swallowing. Consequently, the duration and amplitude of suprahyoid and infrahyoid muscle activity measured by surface EMG would be a useful indicator of the easy-to-swallow performance. [source] | |||||||||||||