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Neuromuscular Function (neuromuscular + function)

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Medical Sciences	90%

Selected Abstracts

Neuromuscular function in healthy occlusion

JOURNAL OF ORAL REHABILITATION, Issue 9 2010
S. E. FORRESTER
Summary, This study aimed to measure neuromuscular function for the masticatory muscles under a range of occlusal conditions in healthy, dentate adults. Forty-one subjects conducted maximum voluntary clenches under nine different occlusal loading conditions encompassing bilateral posterior teeth contacts with the mandible in different positions, anterior teeth contacts and unilateral posterior teeth contacts. Surface electromyography was recorded bilaterally from the anterior temporalis, superficial masseter, sternocleidomastoid, anterior digastric and trapezius muscles. Clench condition had a significant effect on muscle function (P = 0·0000) with the maximum function obtained for occlusions with bilateral posterior contacts and the mandible in a stable centric position. The remaining contact points and moving the mandible to a protruded position, whilst keeping posterior contacts, resulted in significantly lower muscle activities. Clench condition also had a significant effect on the per cent overlap, anterior,posterior and torque coefficients (P = 0·0000,0·0024), which describe the degree of symmetry in these muscle activities. Bilateral posterior contact conditions had significantly greater symmetry in muscle activities than anterior contact conditions. Activity in the sternocleidomastoid, anterior digastric and trapezius was consistently low for all clench conditions, i.e. <20% of the maximum voluntary contraction level. In conclusion, during maximum voluntary clenches in a healthy population, maximum masticatory muscle activity requires bilateral posterior contacts and the mandible to be in a stable centric position, whilst with anterior teeth contacts, both the muscle activity and the degree of symmetry in muscle activity are significantly reduced. [source]

Neuromuscular function and balance of prepubertal and pubertal blind and sighted boys

ACTA PAEDIATRICA, Issue 10 2006
Arja Häkkinen
Abstract Aim: To compare the neuromuscular function and balance of blind prepuberty- and puberty-aged boys to those with normal sight. Methods: Thirty-three prepubertal (aged 9,13 y) and pubertal (aged 15,18 y) blind and sighted boys were tested for muscle mass thickness, electromyography and maximal isometric strength, dynamic explosive actions, and balance. Results: There was no difference in the muscle mass thickness, maximal strength or vertical jump between the blind and sighted boys. However, fitness-ball throwing and five-jump distances were significantly shorter in both blind groups compared to the sighted groups. One-leg stance of the prepuberty-aged sighted boys was 109 (67) s and in blind boys 32 (12) s, and in the puberty-aged boys 120 (57) s and 31 (8) s, respectively. When vision was blocked in the sighted boys, differences between the blind and sighted boys disappeared. Conclusion: The results showed comparable performance between prepubertal and pubertal blind and sighted boys in the static physical fitness tests. However, balance and performance in dynamic multi-joint tests did not improve similarly in the blind groups compared to sighted groups, indicating that maturation, learning and experience by themselves cannot compensate for the loss of sight. [source]

Severely impaired neuromuscular synaptic transmission causes muscle weakness in the Cacna1a -mutant mouse rolling Nagoya

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2007
Simon Kaja
Abstract The ataxic mouse rolling Nagoya (RN) carries a missense mutation in the Cacna1a gene, encoding the pore-forming subunit of neuronal Cav2.1 (P/Q-type) Ca2+ channels. Besides being the predominant type of Cav channel in the cerebellum, Cav2.1 channels mediate acetylcholine (ACh) release at the peripheral neuromuscular junction (NMJ). Therefore, Cav2.1 dysfunction induced by the RN mutation may disturb ACh release at the NMJ. The dysfunction may resemble the situation in Lambert,Eaton myasthenic syndrome (LEMS), in which autoantibodies target Cav2.1 channels at NMJs, inducing severely reduced ACh release and resulting in muscle weakness. We tested neuromuscular function of RN mice and characterized transmitter release properties at their NMJs in diaphragm, soleus and flexor digitorum brevis muscles. Clinical muscle weakness and fatigue were demonstrated using repetitive nerve-stimulation electromyography, grip strength testing and an inverted grid hanging test. Muscle contraction experiments showed a compromised safety factor of neuromuscular transmission. In ex vivo electrophysiological experiments we found severely impaired ACh release. Compared to wild-type, RN NMJs had 50,75% lower nerve stimulation-evoked transmitter release, explaining the observed muscle weakness. Surprisingly, the reduction in evoked release was accompanied by an ,,3-fold increase in spontaneous ACh release. This synaptic phenotype suggests a complex effect of the RN mutation on different functional Cav2.1 channel parameters, presumably with a positive shift in activation potential as a prevailing feature. Taken together, our studies indicate that the gait abnormality of RN mice is due to a combination of ataxia and muscle weakness and that RN models aspects of the NMJ dysfunction in LEMS. [source]

The European Male Ageing Study (EMAS): design, methods and recruitment

INTERNATIONAL JOURNAL OF ANDROLOGY, Issue 1 2009
David M. Lee
Summary Life expectancy is increasing in most developed countries, in part due to improved socioeconomic conditions and in part to advances in healthcare. It is widely acknowledged that the promotion of healthy ageing by delaying, minimizing or preventing disabilities or diseases is one of the most important public health objectives in this century. In contrast to the menopausal transition in females, we know relatively little about the contribution of androgens and anabolic hormones to the quality of ageing in men. The European Male Ageing Study (EMAS) is a multicentre prospective cohort designed to examine the prevalence, incidence and geographical distribution of gender-specific and general symptoms of ageing in men, including their endocrine, genetic and psychosocial predictors. Men aged 40,79 years were recruited from eight European centres: Florence (Italy), Leuven (Belgium), Lodz (Poland), Malmö (Sweden), Manchester (UK), Santiago de Compostela (Spain), Szeged (Hungary) and Tartu (Estonia). Subjects were recruited from population registers and those who agreed to take part completed a detailed questionnaire including aspects of personal and medical history, lifestyle factors and sexual function. Objective measures of body size, cognition, vision, skeletal health and neuromuscular function were obtained. Blood and DNA specimens were collected for a range of biochemical and genetic analyses. After an average of 4 years, it is planned to resurvey the participants with similar assessments. A total of 3369 men with a mean age of 60 ± 11 years were recruited. The mean centre response rate was 43%, and highest in those aged 50,59 years. Those who participated were marginally younger than those who were invited but declined to participate (60.0 vs. 61.1 years). Participants left education slightly later than a sample of non-participants, though there were no consistent differences in levels of general health, physical activity, or smoking. EMAS will provide new population-based data concerning the main features that characterize ageing in men and its critical determinants, particularly with reference to age-related changes in hormone levels. Such information is an important prerequisite to develop effective strategies to reduce age-related disabilities and optimise health and well-being into old-age. [source]

The use of desflurane or propofol in combination with remifentanil in myasthenic patients undergoing a video-assisted thoracoscopic-extended thymectomy

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 3 2009
P. GRITTI
Background: Although several studies of the use of desflurane in anesthesia have revealed many desirable qualities, there are no data on the use and effects especially on the neuromuscular function of desflurane on myasthenia gravis (MG) patients. The purpose of this study was to evaluate the use of either desflurane or propofol, both combined with remifentanil, in patients with MG undergoing a video-assisted thoracoscopic-extended thymectomy (VATET). Methods: Thirty-six MG patients who underwent VATET were enrolled. Nineteen patients were anesthetized with remifentanil and propofol infused with a target-controlled infusion plasma model, and 17 patients with desflurane and remifentanil. No muscle relaxant was used. The intubating conditions, hemodynamic and respiratory changes, neuromuscular transmission and post-operative complications were evaluated. Results: Neuromuscular transmission was significantly decreased in the desflurane group (6.7%, from 3% to 9% during anesthesia P=<0.05). The intubating conditions were good in all 36 patients and 35 patients were successfully extubated in the operating room. The time-to-awakening, post-operatory pH and base excess were significantly different in the two groups, with a decreasing mean arterial pressure in the group administered with desflurane. No patients required reintubation due to myasthenic or cholinergic crisis, or respiratory failure. No other significant differences between the two groups studied were observed. Conclusion: Our experience indicates that anesthesia with desflurane plus remifentanil in patients with MG could determine a reversible muscle relaxation effect, but with no clinical implication, allowing a faster recovery with no difference in extubation time and post-operative complications in the two groups. [source]

Neuromuscular function in healthy occlusion

Probability of acceptable intubation conditions with low dose rocuronium during light sevoflurane anaesthesia in children

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 8 2001
M. Eikermann
Background: To define the rocuronium doses which would provide 50%, 90%, and 95% probability of ,acceptable' intubation conditions during light sevoflurane anaesthesia, we studied 60 children aged 2,7 years in a prospective, randomised, assessor blinded study. Methods: After mask ventilation with 1 MAC sevoflurane/N2O for 17±1 (x̌±SD) min we administered rocuronium (either 0.15, 0.22, 0.3, 0.5, or 1.0 mg ,· ,kg,1) or placebo, and quantified the evoked force of the adductor pollicis muscle. Intubation conditions were assessed before and 2 min after injection of the test drug. Results: Intubation conditions were improved significantly with rocuronium and scored ,acceptable' in 70%, 90%, and 100% of the children after injection of rocuronium 0.15, 0.22, and 0.3 mg ,· ,kg,1, respectively. In parallel, twitch tension decreased to 53% (6,100), 26% (11,100), and 11% (0,19) of baseline (median (range)). Recovery of train-of-four ratio to 0.8 was achieved 13 (7,19), 16 (8,28), and 27 (23,44) min after injection of the respective rocuronium doses. Higher rocuronium doses did not further improve intubation conditions but only prolonged time of neuromuscular recovery. Logistic regression analysis revealed that rocuronium 0.11 (CI 0.05,0.16), 0.21 (0.14,0.28), and 0.25 (0.15,0.34) mg ,· ,kg,1 provides a 50%, 90%, and 95% probability of ,acceptable' intubation conditions in children during 1 MAC sevoflurane/N2O anaesthesia, respectively. Furthermore, we calculated that force depression of adductor pollicis muscle to 81% (CI 72,90), 58% (42,74), and 50% (29,71) of baseline is associated with 50%, 90%, and 95% probability of ,acceptable' intubation conditions. Conclusions: Submaximal depression of muscle force with low dose rocuronium improves intubation conditions in children during light sevoflurane anaesthesia while allowing rapid recovery of neuromuscular function. However, when using low dose rocuronium neuromuscular monitoring may be helpful to detect children with inadequate response to the relaxant so as to avoid an unsuccessful intubation attempt. [source]

Recovery from neuromuscular blockade: a survey of practice,

ANAESTHESIA, Issue 8 2007
M. Grayling
Summary At present in the UK there is no consensus regarding the parameters anaesthetists use to indicate adequacy of reversal from neuromuscular blockade. In an attempt to determine current practice, we carried out a survey covering 12 anaesthetic departments throughout the UK. Individuals were asked to give details regarding their usage of available monitors or, alternatively, to list those clinical parameters which they felt offered the best guidance as to the adequacy of recovery from neuromuscular blockade. There was no consensus among anaesthetists as to the most reliable clinical signs of recovery from neuromuscular blockade. There was an apparent lack of understanding of the limitations of some clinical signs used to determine recovery, as well as inappropriate application of others. In all departments where monitors (quantitative or qualitative) were available, there was limited knowledge regarding the current minimum recommended train-of-four ratio which should be observed prior to extubation. There is an apparent overall confusion among clinicians as to the best method to confirm recovery from neuromuscular blockade. This is probably due to the lack of a single reliable clinical test which can be applied in the immediate postoperative period. Insufficient reliance is placed upon the use of quantitative monitors. There is a lack of clarity in national anaesthetic guidelines with respect to monitoring of neuromuscular function. Current standards need to be re-assessed in the light of recent improvements in nerve stimulators. [source]

Pathology is alleviated by doxycycline in a laminin-,2,null model of congenital muscular dystrophy

ANNALS OF NEUROLOGY, Issue 1 2009
Mahasweta Girgenrath PhD
Objective Congenital muscular dystrophy type 1A is an autosomal recessive disease that is caused by loss-of-function mutations in the laminin-,2 gene, and results in motor nerve and skeletal muscle dysfunction. In a previous study, we used genetic modifications to show that inappropriate induction of apoptosis was a significant contributor to pathogenesis in a laminin-,2,deficient mouse model of congenital muscular dystrophy type 1A. To identify a possible pharmacological therapy for laminin-,2 deficiency, we designed this study to determine whether treatment with minocycline or doxycycline, which are tetracycline derivatives reported to have antiapoptotic effects in mammals, would significantly increase lifespan and improve neuromuscular function in laminin-,2,deficient mice. Methods Mice that were homozygous for a targeted, inactivating mutation of the laminin-,2 gene were placed into control, minocycline-treated, or doxycycline-treated groups. Drug treatment began within 2 weeks of birth, and the progression of disease was followed over time using behavioral, growth, histological, and molecular assays. Results We found that treatment with either minocycline or doxycycline increased the median lifespan of laminin-,2,null mice from approximately 32 days to approximately 70 days. Furthermore, doxycycline improved postnatal growth rate and delayed the onset of hind-limb paralysis. Doxycycline-treated laminin-,2,deficient muscles had increased Akt phosphorylation, decreased inflammation, and decreased levels of Bax protein, terminal deoxynucleotidyltransferase,mediated dUTP nick end labeling,positive myonuclei, and activated caspase-3. Interpretation Doxycycline or other drugs with similar functional profiles may be a possible route to improving neuromuscular dysfunction caused by laminin-,2-deficiency. Ann Neurol 2008 [source]

Clinical Practice of Functional Electrical Stimulation: From "Yesterday" to "Today"

ARTIFICIAL ORGANS, Issue 8 2008
Milan R. DimitrijevicArticle first published online: 18 AUG 200
Abstract:, Functional electrical stimulation (FES) is an accepted treatment method for paresis or paralysis after spinal cord and head injury as well as stroke and other neurological upper motor neuron disorders. At the beginning, FES worked like an electrophysiological brace for the correction of drop foot of patients after a stroke. When analyzing early accomplishments, it becomes evident that FES was influenced rather by technological and biomedical engineering development than by contemporary knowledge on neurocontrol of movement in individuals with upper motor neuron paralysis. Nevertheless, with better understanding of pathophysiology of spasticity and neurocontrol of impaired movement, FES advanced from an electrophysiological brace to a treatment modality for the improvement of muscle control, neuroaugmentation of residual movements, and supportive procedure for "spontaneous recovery" of motor control. In the present article we shall illustrate barriers which delayed FES to be applied in clinical practice of neuron rehabilitation from "Yesterday" to "Today." We shall discuss the importance to apply FES early after the onset of neurological conditions to prevent disuse of noninjured portions of the CNS. Moreover, FES can play a significant role in the supporting processes of neuroplasticity in the subacute phase of upper motor neuron dysfunction. Therefore, the electrophysiological brace of "Yesterday" provides "Today" a correction of missing neuromuscular function. At the same time, it is an active external device for the correction of motor deficits interacting with the somatosensory-motor integration. Thus, "Yesterday" and "Today" of the same technological approach can be very different, thanks to a different understanding and assessment of "external" and "internal" components of human motor control. [source]