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Chair design and the anesthesia provider.

Anesthesia providers spend a considerable amount of time sitting in poorly designed chairs. In the majority of hospitals, anesthesia providers are reluctant to request ergonomically designed chairs for the operating room. Multiple studies have given conclusive evidence that properly designed chairs reduce low back pain, improve lower extremity circulation, and relieve muscle tension, thus increasing overall comfort. Continual use of poorly designed chairs and stools in the operating room will cause eventual health complaints. Ergonomically designed chairs will be a wise purchase for the anesthesia provider, especially those who are aging or have physical complaints related to the back, muscle tension, and other lower extremity problems.

Equipment Design↗

Acute effects of transient vertical whole-body vibration.

The question as to whether shock-type whole-body vibration causes increasingly acute strain was investigated. Random vibrations were superimposed with shocks differing in amplitude and in number per unit of time in a systematic manner. The weighted root mean square (rms) acceleration was kept constant in all over the varied experiments. A total of 17 men were exposed to vibration from an electrohydraulic simulator. The following strain criteria were used: biodynamic behavior of the trunk and the head, electrical activity of the muscles of the back and the neck, subjective sensation, skin temperature in the lumbar area and visual and tracking performance. It was found that increasing shock amplitude and, in some experiments, also increasing numbers of shocks led to increasingly acute effects that varied, depending on the kind of shock used. New methods should be developed for the assessment of transient vibration that are better than the existing standards.

Acceleration↗

Correlation of macro and micro cardiovascular function during weightlessness and simulated weightlessness.

The investigation of cardiovascular function necessarily involves a consideration of the exchange of substances at the capillary. If cardiovascular function is compromised or in any way altered during exposure to zero gravity in space, then it stands to reason that microvascular function is also modified. We have shown that an increase in cardiac output similar to that reported during simulated weightlessness is associated with a doubling of the number of post-capillary venules and a reduction in the number of arterioles by 35%. If the weightlessness of space travel produces similar changes in cardiopulmonary volume and cardiac output, a reasonable expectation is that astronauts will undergo venous neovascularization. We have developed an animal model in which to correlate microvascular and systemic cardiovascular function. The microcirculatory preparation consists of a lightweight, thermo-neutral chamber implanted around intact skeletal muscle on the back of a rat. Using this technique, the performed microvasculature of the cutaneous maximus muscle may be observed in the conscious, unanesthetized animal. Microcirculatory variables which may be obtained include venular and arteriolar numbers, lengths and diameters, single vessel flow velocities, vasomotion, capillary hematocrit anastomoses and orders of branching. Systemic hemodynamic monitoring of cardiac output by electromagnetic flowmetry, and arterial and venous pressures allows correlation of macro- and microcirculatory changes at the same time, in the same animal. Observed and calculated hemodynamic variables also include pulse pressure, heart rate, stroke volume, total peripheral resistance, aortic compliance, minute work, peak aortic flow velocity and systolic time interval. In this manner, an integrated assessment of total cardiovascular function may be obtained in the same animal without the complicating influence of anesthetics.

Animals↗

[Facial rejuvenation and concentric malar lift: the FACE RECURVE concept].

Cell ageing is responsible for the increasingly creased appearance of our skin. The ageing of the structures of the face is attributed primarily to the effect of gravity on the tissues. The theory expounded below sets out to prove that the main and initial cause of this ageing is the repeated contractions of the mimic muscles. This concept attributes only a secondary role to gravity in the ageing process, which is initially brought about by muscular contractions. An MRI study recently made it possible to demonstrate the anterior convexity curve of the mimic muscles in the young subject. This curve is due to the existence at the back of these muscles of a deep fat pad. In the young subject, the extent of its convexity and its location give a specific, youthful character to the movements, in terms of direction and amplitude, of the facial muscles. With age, the muscle gradually straightens and shortens due to the repeated contractions that expel the underlying fat and increase the tonus at rest. The application of these new findings to the ageing of the face gives rise to new technical possibilities both in the field of medicine and aesthetic surgery. These new techniques have the same targets: segments of the mimic muscles (maintain over time a good muscular curve and a low tonus at rest) and the underlying fatty convexities. As far as medicine is concerned, the combination of botulinum toxin and filling has proved its worth. But two technical elements are new: the filling products must, at several points, be injected primarily behind the muscle to treat the depressions naturally and restore the initial curve of the overlying muscle. A very low number of units (a quarter to one unit) of botulinum toxin must be injected into certain muscles to diminish the tonus at rest of these muscles without diminishing their strength in maximum contraction. In surgery, new possibilities to treat premature ageing include procedures that combine segmentary muscular weakening, micro liposuctions and retromuscular reinjections. The advantage with regard to the medical procedures is greater stability over time and the greater precision of these muscular actions (one third of a muscle can be weakened for example) and the fat reinjections can be more stable. These procedures can be performed under local anesthesia. In cases of more advanced ageing, surgery offers new treatment possibilities that include, for the midface region, the concentric malar lift. It replaces, on the orbital rim, the sub-orbicularis oculi fat that has descended eccentrically as a result of the contractions of the orbicularis oculi muscle. The procedure, using the subperiosteal detachment plane, is therefore stable over time. At the same time, specific muscles are weakened. The aims of restoring fatty volumes and muscular tonuses are thus achieved. Similarly, in the neck, the platysma muscle is specifically weakened. Each area is studied in line with its specificities. For the first time, the skin tension of the facelift has no more to be maximum to treat the relief of the jawl line, of the palpebro malar groove and so on. The skin tension becomes moderate, just to remove the excess of skin. The relief is faded with the specific muscular and fatty action. The name of this new concept is Face Recurve.

Aging↗

[Anatomic study of the aponeurosis of the posterior spinal muscles].

A macroscopic study of the lumbar regions of 4 adult bodies and of 4 foetuses has been made by the authors to specify the inferior insertion of the deep muscles of the back. These observations have demonstrated that the longissimus dorsi, and the ilio-costalis muscles are separated by a sagittal aponeurosis. The aponeurosis is a ventral reflection of the aponeurotic fascia of the Erector Spinae.

Fascia↗

The effectiveness of four interventions for the prevention of low back pain.

OBJECTIVE: Low back pain affects 60% to 80% of US adults at some time during their lives. This review evaluates the effectiveness of four strategies to prevent low back pain for asymptomatic individuals: back and aerobic exercises, education, mechanical supports (corsets), and risk factor modification. DATA SOURCES: The MEDLINE database was searched for all relevant articles published in English between 1966 and 1993. Bibliographies of identified articles were searched to ensure that all pertinent articles had been gathered and back pain specialists reviewed our final bibliography for completeness. STUDY SELECTION AND DATA EXTRACTION: A total of 190 articles were identified, and the 64 that contained original data about preventing low back pain were reviewed. Studies were graded according to strength of study design. DATA SYNTHESIS: There is limited evidence based on randomized trials and epidemiological studies that exercises to strengthen back or abdominal muscles and to improve overall fitness can decrease the incidence and duration of low back pain episodes. There is minimal evidence to support the use of educational strategies to prevent low back pain and insufficient evidence to recommend about the use of mechanical supports. Although there is no evidence supporting risk factor modification for preventing low back pain (smoking cessation and weight loss), there are other reasons to recommend the interventions. CONCLUSION: There is limited evidence to recommend exercise to prevent low back pain in asymptomatic individuals, but there is insufficient evidence to recommend other prevention strategies. These conclusions should be viewed cautiously since they are primarily based on studies conducted in the workplace rather than in clinical settings.

Behavior Therapy↗

Electromyographic biofeedback for pain related to muscle tension. A study of tension headache, back, and jaw pain.

We review the literature on the application of electromyographic (EMG) biofeedback to tension-related headaches, back and shoulder pain, and temporomandibular joint (TMJ) pain and present clinical treatment data on 18 patients with tension headaches, eight patients with back and shoulder pain, and six patients with TMJ pain. Electromyographic tension levels declined in all groups of patients; pain declined significantly in 12 of 18 patients with tension headaches and one of eight back pain patients, and decreased slightly in three headache patients, three back and shoulder pain patients, and two patients with TMJ pain. Conclusions suggest that EMG biofeedback is generally more effective in treating tension headaches, but much less effective in the treatment of back, shoulder, or jaw pain, although the numbers of patients are small in the latter two groups.

Adolescent↗

Halves of epithelial somites and segmental plate show distinct muscle differentiation behavior in vitro compared to entire somites and segmental plate.

Medial and lateral halves of the somite are known to differ with respect to their developmental fates: Cells from the medial half of the somite give rise to the epaxial muscle of the back and cells from the lateral half of the somite give rise to the skeletal muscles of the limbs and the ventrolateral body wall. To get a better insight into myogenic determination of somite hemispheres, isolated entire somites as well as medial and lateral parts of somites and of segmental plate from 2 day chick embryos were explanted in vitro. These parts of the paraxial mesoderm were also cocultured in contact with somite surrounding tissues such as neural tube lacking floorplate, neural tube including notochord-floorplate complex, and intermediate mesoderm, which were examined with respect to their muscle promoting or inhibiting influences. Skeletal muscle differentiation was monitored by the use of anti-myosin heavy chain antibody (MF20). It is shown that medial and lateral halves of segmental plate and epithelial somites are capable of undergoing myogenesis in the absence of axial organs. In contrast, cultures of intact segmental plate and epithelial somites from the same levels did not show muscle differentiation. Neural tube lacking floorplate promoted muscle differentiation in the medial halves especially of epithelial somites and also of segmental plate, but not in the lateral halves of the paraxial mesoderm at these levels. Intermediate mesoderm was found to inhibit muscle differentiation in medial and lateral halves of segmental plate and of epithelial somites. We further demonstrate that the arrangement of the myoblasts within tissue cultures is influenced by the presence or absence of axial organs.

Animals↗

Tetrodotoxin-resistant sodium channels.

1. Tetrodotoxin (TTX) has been widely used as a chemical tool for blocking Na+ channels. However, reports are accumulating that some Na+ channels are resistant to TTX in various tissues and in different animal species. Studying the sensitivity of Na+ channels to TTX may provide us with an insight into the evolution of Na+ channels. 2. Na+ channels present in TTX-carrying animals such as pufferfish and some types of shellfish, frogs, salamanders, octopuses, etc., are resistant to TTX. 3. Denervation converts TTX-sensitive Na+ channels to TTX-resistant ones in skeletal muscle cells, i.e., reverting-back phenomenon. Also, undifferentiated skeletal muscle cells contain TTX-resistant Na+ channels. Cardiac muscle cells and some types of smooth muscle cells are considerably insensitive to TTX. 4. TTX-resistant Na+ channels have been found in cell bodies of many peripheral nervous system (PNS) neurons in both immature and mature animals. However, TTX-resistant Na+ channels have been reported in only a few types of central nervous system (CNS). Axons of PNS and CNS neurons are sensitive to TTX. However, some glial cells have TTX-resistant Na+ channels. 5. Properties of TTX-sensitive and TTX-resistant Na+ channels are different. Like Ca2+ channels, TTX-resistant Na+ channels can be blocked by inorganic (Co2+, Mn2+, Ni2+, Cd2+, Zn2+, La3+) and organic (D-600) Ca2+ channel blockers. Usually, TTX-resistant Na+ channels show smaller single-channel conductance, slower kinetics, and a more positive current-voltage relation than TTX-sensitive ones. 6. Molecular aspects of the TTX-resistant Na+ channel have been described. The structure of the channel has been revealed, and changing its amino acid(s) alters the sensitivity of the Na+ channel to TTX. 7. TTX-sensitive Na+ channels seem to be used preferentially in differentiated cells and in higher animals instead of TTX-resistant Na+ channels for rapid and effective processing of information. 8. Possible evolution courses for Na+ and Ca2+ channels are discussed with regard to ontogenesis and phylogenesis.

Animals↗

Changes in electrical activity in muscles resulting from chiropractic adjustment: a pilot study.

This study examines the effects of chiropractic adjustment on the muscles of the back. Vertebrae that are hypomobile may be held in that state by the erector spinae muscle group; adjusting such vertebrae should result in less muscle tension. By measuring the change in electrical activity, such relaxation can be observed. Hypomobile vertebrae were found by motion palpation. The patient was then placed prone and surface electrodes were placed over the upper trapezius, upper erector spinae (T3-T5), and lumbar erector spinae (L1-L3) muscle groups on both sides of the body. The patient was adjusted using full spine toggle recoil thrusts, and postadjustment readings were taken. Results from this study show that significant changes in muscle electrical activity occur as a consequence of adjusting. On average, a 25% reduction in muscle activity was observed across the 20 subjects tested, while no significant reductions were observed with the control group of 14 subjects. Significant reductions in side-to-side imbalances were also observed.

Adult↗

Skeletal muscle relaxant use in the United States: data from the Third National Health and Nutrition Examination Survey (NHANES III).

STUDY DESIGN: Population-based cross-sectional prevalence survey. OBJECTIVES: To define muscle relaxant use patterns in the United States. SUMMARY OF BACKGROUND DATA: Despite a long history of use for back pain and musculoskeletal disorders, national prevalence patterns of prescription muscle relaxant use have not been defined. METHODS: NHANES III (1988-1994) is an in-person health examination survey of the U.S. civilian population, based on a complex, multistage probability sample design. RESULTS: An estimated 2 million American adults reported muscle relaxant use (1-month period prevalence 1.0%; 95% confidence interval 0.8-1.3%). While virtually all (94%) used individual muscle relaxants rather than fixed combination muscle relaxant analgesics, two thirds took an additional prescription analgesic. Men and women had similar usage. Median user age was 42 years, but 16% of users were older than 60 years. Eighty-five percent of users took muscle relaxants for back pain or muscle disorders. Two thirds of muscle relaxant users had histories of recent back pain; however, only 4% of all those with a recent history of back pain reported any muscle relaxant use. Mean length of use was 2.1 years (95% confidence interval 1.6-2.6), with 44.5% taking medication longer than a year (95% confidence interval 35.7-53.3). Muscle relaxant use in the elderly, among older persons with ambulatory impairments, and in chronic obstructive pulmonary disease appeared undiminished compared with general population use. CONCLUSIONS: Although typically recommended for short-term treatment of back pain, muscle relaxants are often used chronically and are prescribed to subpopulations potentially at risk for adverse effects.

Adolescent↗

Sports injuries in footballers related to defects of posture and body mechanics.

The objective of this study was to investigate possible relationships between the incidence of sports injury and the existence of body mechanics defects in players of various codes of football. Injuries were recorded prospectively over a 24 month period. Fifteen aspects of body mechanics were evaluated at the start of the study using a specially developed photogrammetric technique known to have high reliability and sensitivity. It was found that subjects who suffered from ankle injuries had lower mean scores for ankle mechanics than the non-injured players. Knee injuries were found to be associated with lumbar lordosis and sway back. Subjects who suffered from muscle strains had a higher incidence of lumbar lordosis, sway back and abnormal knee inter-space. Back injuries were associated with poor shoulder symmetry, scapulae abduction, back asymmetry, kyphosis, lordosis and scoliosis. Subjects who suffered from two or more injuries had lower overall body mechanics scores than the other subjects. In general, it was found that the incidence of ankle, back, knee and muscle injuries was influenced by the presence of defects of body mechanics. These results suggest that intervention to improve body mechanics would be likely to reduce the incidence of sports injuries in football.

Adolescent↗

Regulation of paraxis expression and somite formation by ectoderm- and neural tube-derived signals.

During vertebrate embryogenesis, the paraxial mesoderm becomes segmented into somites, which form as paired epithelial spheres with a periodicity that reflects the segmental organization of the embryo. As a somite matures, the ventral region gives rise to a mesenchymal cell population, the sclerotome, that forms the axial skeleton. The dorsal region of the somite remains epithelial and is called dermomyotome. The dermomyotome gives rise to the trunk and limb muscle and to the dermis of the back. Epaxial and hypaxial muscle precursors can be attributed to distinct somitic compartments which are laid down prior to overt somite differentiation. Inductive signals from the neural tube, notochord, and overlying ectoderm have been shown to be required for patterning of the somites into these different compartments. Paraxis is a basic helix-loop-helix transcription factor expressed in the unsegmented paraxial mesoderm and throughout epithelial somites before becoming restricted to epithelial cells of the dermomyotome. To determine whether paraxis might be a target for inductive signals that influence somite patterning, we examined the influence of axial structures and surface ectoderm on paraxis expression by performing microsurgical operations on chick embryos. These studies revealed two distinct phases of paraxis expression, an early phase in the paraxial mesoderm that is dependent on signals from the ectoderm and independent of the neural tube, and a later phase that is supported by redundant signals from the ectoderm and neural tube. Under experimental conditions in which paraxis failed to be expressed, cells from the paraxial mesoderm failed to epithelialize and somites were not formed. We also performed an RT-PCR analysis of combined tissue explants in vitro and confirmed that surface ectoderm is sufficient to induce paraxis expression in segmental plate mesoderm. These results demonstrate that somite formation requires signals from adjacent cell types and that the paraxis gene is a target for the signal transduction pathways that regulate somitogenesis.

Amino Acid Sequence↗

Childhood glioblastoma multiforme of the spinal cord.

Astrocytoma accounts for more than 50% of all central nervous system tumours diagnosed, with particular prevalence in the 15- to 34-year-old age bracket, rarely arising in younger children. In 1995, a 7-year-old boy presented in Emergency with a 3-day history of severe radicular back pain and associated muscle spasms, exacerbated by lying on his back. Both bone scan and plain X-rays were unremarkable; however, MRI showed a 3-cm space-occupying lesion at the level of T5-T6. The patient proceeded to biopsy and partial excision of the tumour through laminectomy, histology confirming an anaplastic astrocytoma (glioblastoma multiforme), St Anne Mayo grade 4. Treatment consisted of a radical course of radiotherapy alone, delivering a total dose of 44.8 Gy at 1.6 Gy per fraction. The treatment comprised of three phases using two oblique wedged fields on a 6 MV linear accelerator. The patient remains disease free 7 years post treatment, with the only effect noted being a slight kyphoscoliosis at the site of the laminectomy and radiation. This report highlights the efficacy of combined surgery and radiation therapy in the management of spinal cord glioblastoma multiforme in preventing tumour recurrence, with acceptable morbidity. Further evaluation of the treatment efficacy would be difficult because of the scarcity of such cases.

Child↗

The effect of back belt use on isometric lifting force and fatigue of the lumbar paraspinal muscles.

STUDY DESIGN: A repeated measures multivariate design to assess the effect of back belts on isometric lifting force and lumbar paraspinal muscle fatigue. OBJECTIVE: To determine the efficacy of lumbar back belts in minimizing a loss in isometric force production and fatigue of lumbar paraspinal muscles. SUMMARY OF BACKGROUND DATA: Increased prevalence of back belts in industry and lack of scientific evidence supporting them suggested additional research was needed. There has been no conclusive research to substantiate manufacturer claims that use of belts reduces fatigue of lumbar paraspinals. METHODS: Twenty-four subjects, 13 men and 11 women, were tested twice: once with and once without a belt. All subjects performed a dynamic lifting task at a rate of 10 lifts per minute for 20 minutes. Surface electromyograms from the lumbar paraspinals and isometric force measurements were recorded during a static maximal isometric lift at 0, 10, and 20 minutes. Load during the dynamic task was determined as 20% of initial maximum isometric force. Electromyographic data were used to detect changes in median power spectral frequencies. Muscular fatigue was indicated by a reduction in median power spectral frequency values or a decrease in isometric force-generating capacity. RESULTS: Multivariate and univariate analyses suggest that there is no effect on lumbar paraspinal muscle fatigue or isometric lifting force production as a result of back belt use. CONCLUSIONS: These findings do not support the use of back belts for the purpose of minimizing either lumbar paraspinal muscle fatigue or a loss in isometric lifting force production.

Adult↗

[Physiotherapy in lumbar disc herniation ].

Physiotherapy is the treatment of choice in patients with symptoms caused by a lumbar disc herniation. In clinical practice a broad range of physiotherapeutic modalities has been revealed to be helpful. During the acute stage the efficacy of the McKenzie-concept, mobilisation therapies and traction has been demonstrated in randomized controlled trials with a blind assessor. In addition, pain reducing physical therapies such as cold or electrotherapy and non-steroidal anti-inflammatory drugs, analgesics and/or muscle relaxants are sensible initial accompanying treatments. The effectiveness of active physiotherapies such as training of local strength endurance of back and abdominal muscles has been proven in patients during the chronic stage. The indications for a in-patient rehabilitation programme, for surgery and the danger of developing chronic low back pain are discussed.

Cauda Equina↗