Intra-rater reliability of electromyographic recordings and subjective evaluation of neck muscle fatigue among helicopter pilots.

The aim was to evaluate the reliability of a method of measuring neck muscle fatigue among helicopter pilots. METHOD: Surface EMG from three areas in the neck region, bilaterally, was recorded among 10 male helicopter pilots while they were performing isometric contractions in flexion and extension for 45 s, sustaining a force representing 75% of maximum strength in a seated position. Perceived fatigue was rated using the Borg CR-10 scale. The test was repeated twice the first day and then two additional times with one-week intervals. Variables analyzed were the slope of the median frequency change, the normalized slope, and the ratings after 15, 30 and 45 s; and also the initial median frequency (IMDF). The intra-class correlation (ICC) and the measurement error (S(w)), intra- and inter-day were calculated statistically. RESULTS: The best reliability for the slope was found for the 45 s intra-day analysis taking all measurements into account (ICC 0.65-0.83). The reliability after 30 s was poorer but still acceptable (ICC 0.52-0.71). For the subjective ratings, the highest reliability was found after 30 s inter-day (ICC 0.86-0.88). IMDF showed generally high reliability for the intra-day analyses (ICC 0.63-0.80). CONCLUSION: The method is reliable for use in further research. Since performing a contraction of 75% of maximum was quite strenuous, we recommend that the protocol be shortened to 30 s.     

Neuromuscular adaptation in experimental and clinical neck pain.

The purpose of this brief review is to present evidence from experimental and clinical neck pain studies of pain-induced neuromuscular adaptations. It has been shown that clinical neck pain is associated with a substantial reorganization in the control strategies of cervical muscles during static and dynamic tasks. Experimental neck pain models allow local elicitation of nociceptive afferents, mimicking the sensory aspects of clinical pain, without major changes in muscle properties. These models may help understand the physiological mechanisms underlying the observations from clinical neck pain studies. The knowledge obtained from the interpretation of clinical findings with experimental pain models has relevance for the development of therapeutic interventions for the rehabilitation of patients with neck pain disorders.     

Homer1a signaling in the amygdala counteracts pain-related synaptic plasticity, mGluR1 function and pain behaviors

Voltage-gated sodium channels (VGSCs) play an important role in the control of membrane excitability. We previously reported that the excitability of nociceptor was increased by hypotonic stimulation. The present study tested the effect of hypotonicity on tetrodotoxin-sensitive sodium current (TTX-S current) in cultured trigeminal ganglion (TG) neurons. Our data show that after hypotonic treatment, TTX-S current was increased. In the presence of hypotonicity, voltage-dependent activation curve shifted to the hyperpolarizing direction, while the voltage-dependent inactivation curve was not affected. Transient Receptor Potential Vanilloid 4 receptor (TRPV4) activator increased TTX-S current and hypotonicity-induced increase was markedly attenuated by TRPV4 receptor blockers. We also demonstrate that inhibition of PKC attenuated hypotonicity-induced inhibition, whereas PKA system was not involved in hypotonic-response. We conclude that hypotonic stimulation enhances TTX-S current, which contributes to hypotonicity-induced nociception. TRPV4 receptor and PKC intracellular pathway are involved in the increase of TTX-S current by hypotonicity.     

Observing neck movements evokes an excitatory response in the sympathetic nervous system associated with fear of movement in patients with chronic neck pain

Abstract

The objective of this study was to evaluate the response of the sympathetic-excitatory nervous system in patients with chronic neck pain compared with a control group of asymptomatic subjects who underwent an intervention of watching activities involving movements in the neck region. Thirty participants were divided into two groups: patients with chronic neck pain (n?=?15) and the control group (n?=?15). The patients’ neck disability, fear of movement and catastrophism were assessed with a self-report. The recorded variables related to the autonomic nervous system were skin conductance and skin temperature. The ANOVA test revealed significant differences in the increase in skin conductance in the chronic neck pain group after observing the activities (both in the photographs and video) at the end of the observation and 5?minutes after the intervention (p?<?.01; d?>?0.80). There were no significant differences in skin temperature. Ultimately, the correlation analysis revealed a moderate positive correlation between kinesiophobia and skin conductance at 30?seconds (r?=?0.53) and at 60?seconds (r?=?0.52) of observing the activities in the video for the chronic neck pain group. Based on the results of the present study, we suggest that observing activities involving neck movements causes an activation of the sympathetic-excitatory nervous system in patients with chronic neck pain. These changes could be related to a fear of movement when faced with visual exposure to neck movements that could be interpreted as ‘harmful’ or ‘dangerous’.     

Forward head posture is associated with pressure pain threshold and neck pain duration in university students with subclinical neck pain

Abstract

Objective: The aims of this study are to investigate the association between: (i) forward head posture (FHP) and pressure pain thresholds (PPTs); (ii) FHP and maladaptive cognitive processes; and (iii) FHP and neck pain characteristics in university students with subclinical neck pain.

Materials/methods: A total of 140 university students, 90 asymptomatic and 50 with subclinical neck pain, entered the study. Demographic data, anthropometric data, FHP, and PPTs were collected for both groups. In addition, pain characteristics, pain catastrophizing, and fear of movement were assessed for participants with neck pain. FHP was characterized by the angle between C7, the tragus of the ear, and the horizontal line. Correlation analysis and multivariate regression analysis were conducted.

Results: Participants with subclinical neck pain showed significantly lower PPTs than participants without neck pain (p?<?.05), but similar FHP (p?>?.05). No significant association was found between FHP and PPTs in the asymptomatic group. In the group of participants with subclinical neck pain, PPTs at the right trapezius and neck pain duration explained 19% of the variance of FHP (R²?=?0.23; adjusted R²?=?0.19; p?<?.05).

Conclusion: This study suggests that FHP is not associated with PPTs in asymptomatic university students. In university students with subclinical neck pain, increased FHP was associated with right trapezius hypoalgesia and with neck pain of shorter duration. These findings are in contrast with current assumptions on the association between neck pain and FHP.     

Carotidynia: a cause of neck and face pain.

Carotidynia is a form of vascular neck are face pain in which the vascular change occurs in the carotid artery in the neck. The disorder is not uncommon, and most patients have a prior history of migraine. They present with pain in the neck and face, and are often thought to have a disorder such as chronic sinusitis or trigeminal neuralgia. Diagnosis can be made from the type and location of the pain and the finding of a tender and swollen carotid artery on the same side. Carotidynia responds to the prophylactic medications used for migraine, often disappearing in weeks or months. In some patients the syndrome may become recurrent or chronic, with a variable response to medication.     

The morphology,physiology and function of suboesophageal neck motor neurons in the honeybee

We report some of the neural and muscular circuitry that allows honeybees to control head movements. We studied neck motor neurons with cell bodies in the suboesophageal ganglion, axons in the first cervical nerve (IK1) and terminals in neck muscles 44 and 51 (muscle classification: Snodgrass in Smithsonian Misc Coll 103:1-120, 1942). We show that muscle 44 actually comprises five separate bundles of muscle fibres (subunits), while muscle 51 is split into two subunits. Eight motor neurons innervate muscles 44 and 51. Two motor neurons have cell bodies in the ventral-median cell body group (one innervates a subunit in muscle 44, the other a subunit in muscle 51). One motor neuron has a ventrally located contralateral cell body (innervating a subunit in muscle 44) and five have laterally located ipsilateral cell bodies. Of the five lateral cells, one innervates a subunit in muscle 51, three selectively innervate subunits in muscle 44 and one co-innervates a subunit in muscle 44 with the contralateral cell. Extracellular recordings revealed three types of visually driven, direction-selective cell-types in each IK1 tuned for leftward, rightward and downward motion over the eyes. The spatiotemporal tuning of the units is similar to that of other visual interneurons in the bee brain.     

Spinal manipulation and mobilisation for back and neck pain: a blinded review.

OBJECTIVE--To assess the efficacy of spinal manipulation for patients with back or neck pain. DESIGN--Computer aided search for published papers and blinded assessment of the methods of the studies. SUBJECTS--35 randomised clinical trials comparing spinal manipulation with other treatments. MAIN OUTCOME MEASURES--Score for quality of methods (based on four main categories: study population, interventions, measurement of effect, and data presentation and analysis) and main conclusion of author(s) with regard to spinal manipulation. RESULTS--No trial scored 60 or more points (maximum score 100) suggesting that most were of poor quality. Eighteen studies (51%) showed favourable results for manipulation. In addition, five studies (14%) reported positive results in one or more subgroups. Of the four studies with 50-60 points, one reported that manipulation was better, two reported that manipulation was better in only a subgroup, and one reported that manipulation was no better or worse than reference treatment. Eight trials attempted to compare manipulation with some placebo, with inconsistent results. CONCLUSIONS--Although some results are promising, the efficacy of manipulation has not been convincingly shown. Further trials are needed, but much more attention should be paid to the methods of study.     

Impaired water diuresis in a patient with pseudo-Bartter syndrome.

A 32-year-old man was diagnosed as having pseudo-Bartter syndrome due to surreptitious habitual vomiting and to maldigestion related to decayed teeth. His chief complaints were muscle pain and weakness. In this case, metabolic alkalosis, hypokalemia, hypochloremia, increased plasma renin activity and aldosterone levels were noticed with marked decreases in urinary chloride excretion. Creatinine clearance (GFR) and renal plasma flow (RPF) were also decreased. Blood pressure was normal, but the pressor response to angiotensin II was attenuated. Before treatment with 0.9% saline infusion, plasma vasopressin (AVP) was not suppressed sufficiently by lowering the plasma osmolality (Posm) with an oral water load (WL), but it normally responded to a rise in Posm due to hypertonic saline infusion. Moreover, plasma AVP was normally suppressed by WL after the replenishment of saline. Plasma atrial natriuretic peptide (ANP) was low before WL, but increased normally in response to WL. However, inconsistent with the normal response in this case, decreases in plasma AVP failed to dilute urinary osmolality and to increase urine flow, irrespective of the levels of plasma ANP. These results indicate that chronic inanition due to surreptitious vomiting causes impaired renal diluting ability through decreases in GFR and RPF, irrespective of the levels of plasma AVP and ANP.     

Impaired lung function is associated with obesity and metabolic syndrome in adults

Objective: Impaired lung function is associated with obesity and insulin resistance. In this study, we investigated the relationship between metabolic syndrome and impaired lung function in adults. Research Methods and Procedures: A total of 46,514 subjects 20 years and over (21,669 men and 24,845 women, mean age = 37.3 ± 11.2 and 37.0 ± 11.3 years, respectively) were recruited from four nationwide MJ Health Screening Centers in Taiwan from 1998 to 2000. Metabolic syndrome was defined using the National Cholesterol Education Panel (NCEP) metabolic syndrome criteria or America Heart Association/National Heart Lung Blood Institute (AHA/NHLBI) criteria. The relationship between metabolic syndrome and lung function test was examined using multivariate logistic regression analysis. Results: The prevalence of impaired lung function was 11.1% in men and 14.0% in women. The prevalence of metabolic syndrome was 5.8% using NCEP criteria and 12.8% using AHA/NHLBI criteria. In multivariate logistic regression analysis with adjustment for age, gender, BMI, smoking, alcohol drinking, and physical activity, restrictive lung impairment was independently associated with increased risk of having metabolic syndrome (p < 0.01, odds ratios = 1.221 using NCEP criteria and 1.150 using AHA/NHLBI criteria). Discussion: Obesity and metabolic syndrome were associated with impaired lung function in adults in Taiwan. Our results imply that obesity and insulin resistance may be the common pathways underlying lung function impairment and metabolic syndrome. Moreover, lung function test may be applied as an additional evaluation for metabolic syndrome in a clinical setting.     

Impaired nucleotide excision repair pathway as a possible factor in pathogenesis of head and neck cancer

Tobacco smoking is one of the major risk factors in pathogenesis of head and neck squamous cell carcinomas (HNSCC). Many of the chemical compounds present in tobacco are well-known carcinogens which form adducts with DNA. Cells remove these adducts mainly by the nucleotide excision repair pathway (NER). NER also eliminates a broad spectrum of pyrimidine dimers (CPD) and photo-products (6-4PP) induced by UV-radiation or DNA cross-links after cisplatin anti-cancer treatment. In this study DNA damage and repair was examined in peripheral blood lymphocytes obtained from 20 HNSCC patients and 20 healthy controls as well as HTB-43 larynx and SSC-25 tongue cancer cell lines. DNA repair kinetics in the examined cells after cisplatin or UV-radiation treatment were investigated using alkaline comet assay during 240min of post-treatment incubation. MTT assay was used to analyse cell viability and the Annexin V-FITC kit specific for kinase-3 was employed to determine apoptosis after treating the cells with UV-radiation at dose range from 0.5 to 60J/m(2). NER capability was assessed in vitro with cell extracts by the use of a bacterial plasmid irradiated with UV-light as a substrate for the repair. The results show that lymphocytes from HNSCC patients and HTB-43 or SSC-25 cancer cells were more sensitive to genotoxic treatment with UV-radiation and displayed impaired DNA repair. Also evidenced was a higher rate of apoptosis induction after UV-radiation treatment of lymphocytes from the HNSCC patients and the HTB-43 cancer cells than after treatment of those from healthy donors. Finally, our results showed that there was a significant decrease in NER capacity in HTB-43 or SSC-25 cancer cells as well as in peripheral blood lymphocytes of HNSCC patients compared to controls. In conclusion, we suggest that the impaired NER pathway might be a critical factor in pathogenesis of head and neck cancer.     

Effect of laterality discrimination on joint position sense and cervical range of motion in patients with chronic neck pain: a randomized single-blind clinical trial

Purpose: The main objective of the present study was to evaluate the effects of laterality discrimination training on neck joint position sense and cervical range of motion (ROM) in patients with chronic non-specific neck pain (NSCNP).

Materials and methods: Forty-eight patients with NSCNP were randomly assigned to the neck group (NG) that observed neck images or the foot group (FG) that observed foot images. Response time, response accuracy, cervical ROM, and joint position error (JPE) were the main variables. The secondary outcome measures included psychosocial variables.

Results: Differences between groups in the cervical ROM for flexion (p?=?.043) were obtained, being NG group the one which obtained greater values. NG showed an improvement in right rotation (p?=?.018) and a decrease in flexion was found in the FG (p?=?.039). In JPE, differences between groups were obtained in the left rotation (p?=?.021) and significant changes were found in the NG for flexion, extension, and left rotation movements (p?<?.05). Moderate associations were found between left and right accuracy regarding to post-intervention flexion and right rotation (r?=?0.46, r?=?0.41; p?<?.05) in NG.

Conclusion: Improvements in cervical range of motion and joint position sense are obtained after the performance of the laterality discrimination task of images of the neck but not the feet. Visualization of images of the painful region presents moderate correlations with the accuracy and response time in the movements of flexion and right rotation.