Markus Müntener

A Randomized Clinical Trial of Three Active Therapies for Chronic Low Back Pain

Study Design.A randomized clinical trial.Objectives.To examine the relative efficacy of three active therapies for chronic low back pain.Summary of Background Data.There is much evidence documenting the efficacy of exercise in the conservative management of chronic low back pain, but many questions

Active therapy for chronic low back pain part 3. factors influencing self-rated disability and its change following therapy

Design. Cross-sectional analysis of the factors influencing self-rated disability associated with chronic low back pain and prospective study of the relationship between changes in each of these factors and in disability following active therapy. Objectives. To examine the relative influences of pain, psychological factors, and physiological factors on self-rated disability. Summary of Background Data. In chronic LBP, the interrelationship between physical impairment, pain, and disability is particularly complicated, due to the influence of various psychological factors and the lack of unequivocal methods for assessing impairment. Investigations using new “belief” questionnaires and “sophisticated” performance tests, which have shown promise as discriminating measures of impairment, may assist in clarifying the situation. Previous studies have rarely investigated all these factors simultaneously. Methods. One hundred forty-eight patients with cLBP completed questionnaires and underwent tests of mobility, strength, muscle activation, and fatigability, and (in a subgroup) erector spinae size and fiber size/type distribution. All measures were repeated after 3 months active therapy. Relationships between each factor and self-rated disability (Roland and Morris questionnaire) at baseline, and between the changes in each factor and changes in disability following therapy, were examined. Results. Stepwise linear regression showed that the most significant predictors of disability at baseline were, in decreasing order of importance: pain; psychological distress; fear-avoidance beliefs; muscle activation levels; lumbar range of motion; gender. Only changes in pain, psychological distress, and fear-avoidance beliefs significantly accounted for the changes in disability following therapy. Conclusion. A combination of pain, psychological and physiological factors was best able to predict baseline disability, although its decrease following therapy was determined only by reductions in pain and psychological variables. The active therapy programm—in addition to improving physical function—appeared capable of modifying important psychological factors, possibly as a result of the positive experience of completing the prescribed exercises without undue harm.

Active therapy for chronic low back pain part 1. Effects on back muscle activation, fatigability, and strength.

Design. Randomized prospective study of the effects of three types of active therapy on back muscle function in chronic low back pain patients. Objectives. To quantify the effects of 3 months active therapy on strength, endurance, activation, and fatigability of the back entensor muscles. Summary of Background Data. Many studies have documented an association between chronic low back pain and diminished muscular performance capacity. Few studies have quantified the changes in these measures following interventions using objective measurement techniques or related them to changes in clinical outcome. Methods. A total of 148 individuals (57% women) with chronic low back pain (age, 45.0 ± 10.0 years; duration of low back pain, 10.9 ± 9.5 years) were randomized to a treatment that they attended for 3 months: active physiotherapy, muscle reconditioning on devices, or low-impact aerobics. Before and after therapy, assessments were made of the following: trunk muscle strength (in flexion, extension, lateral bending, and axial rotation), erector spinae activation (maximal, and during forward bending movements), back extensor endurance (Biering-S/orensen test), and erector spinae fatigability (determined from changes in the median frequency of the surface electromyographic signal) during isometric and dynamic tests. Results. A total of 132 of 148 patients (89%) completed the therapy. Isometric strength in each movement direction increased in all groups post-therapy (P < 0.0008), most notably in the devices group. Activation of the erector spinae during the extension tests also increased significantly in all groups and showed a weak, but significant, relationship with increased maximal strength (P = 0.01). Pretherapy 55% of the subjects showed no relaxation of the back muscles at L5 when in the fully flexed position; no changes were observed in any group post-therapy. Endurance time during the Biering-S/orensen test increased significantly post-therapy in all groups (P = 0.0001), but there were no significant changes in EMG-determined fatigability. Fatigability of the lumbar muscles at L5 (EMG median frequency changes) during the dynamic test increased post-therapy (P = 0.0001) without group differences. Conclusion. Significant changes in muscle performance were observed in all three active therapy groups post-therapy, which appeared to be mainly due to changes in neural activation of the lumbar muscles and psychological changes concerning, for example, motivation or pain tolerance.

Posterior surgical approach to the lumbar spine and its effect on the multifidus muscle.

Study Design. This study investigated the changes in the lumbar muscles after posterior fusion of the lumbar spine and the potential correlation between muscular changes and the persistence of low back pain. Objectives. To evaluate prospectively the effect of the posterior approach to the spine on the lumbar erector spinae. Summary of Background Data. The posterior approach to the spine leads to considerable alteration of the erector spinae muscles. An eventual correlation between these changes and persisting pain or other clinical symptoms has not been investigated previously. Methods. Seventy‐five patients undergoing spondylosyndesis for different indications (43 patients) or a second operation for the removal of internal fixation (32 patients) were allotted to the study. In each patient, four biopsy specimens from the lumbar multifidus muscle were harvested; in 14 patients, biopsies were taken at both operations. Size and distribution of the fiber types (I, IIA, IIB, IIC) were determined, and pain scoring (visual analogue scale) and the presence of neurologic deficits were recorded. Results. At the time of the first operation, 88% of the patients showed pathologic changes (altered internal structure, atrophy, type grouping) in one or more biopsies. Statistical analysis showed a correlation between both age and pain and type II (A + B) atrophy. After surgery, the patients showed significantly more biopsies with denervation signs than before surgery. No correlation could be made, however, between the intensity of pain before or after surgery and the relative number of biopsies with signs of denervation. Conclusions. Posterior surgery causes muscular alterations; however, no correlation with pain or other clinical symptoms could be established. Therefore, in the case of unsatisfactory results after surgery of the lumbar spine, reasons other than muscle damage caused by use of the posterior approach must be considered.

Influence of age and duration of symptoms on fibre type distribution and size of the back muscles in chronic low back pain patients

Abstract Many studies have documented an association between chronic low back pain (LBP) and deficits in back muscle strength and endurance. The sub-optimal performance is believed to be the result of alterations in the size and structure of the muscle, although the long-standing issue of whether the observed changes precede or are a consequence of the pain remains unresolved. If consequent to the problem, and predominantly related to disuse of the muscles, then it may be expected that a relationship between muscle structure and symptom duration would exist. Lumbar paraspinal muscle samples were obtained from 59 chronic LBP patients using the percutaneous biopsy technique. The samples were subject to routine histochemical analysis for the examination of muscle fibre type characteristics and cytochemical architectural changes. In 55 of the patients, the gross cross-sectional areas of magnetic resonance images of the trunk muscles were also measured. Multivariate analysis showed that symptom duration was the strongest predictor of the individual proportions of the fast-fatigable type IIX fibres; with age and gender included in the model, nearly 30% of the variance in fibre type distribution could be accounted for. Duration of pain had no influence on fibre size. Gross muscle cross-sectional area correlated directly with lean body mass and inversely with age, but showed no relationship with symptom duration. Pathological changes in the internal fibre structure were more frequently encountered in older patients, and were independent of symptom duration. The results suggest that, over the long term, fibre type transformations rather than alterations in fibre size are the predominant changes to be found in the muscles of chronic LBP patients. The direction of change supports the results of many previous studies that have demonstrated corresponding differences in the fatigability of the muscles. There is a strong case for the early implementation of active measures to attempt to offset the development of these changes in back pain patients.

Active therapy for chronic low back pain Part 2. effects on paraspinal muscle cross-sectional area, fiber type size, and distribution

Design. Randomized prospective study to compare the effects of three types of active therapy on the back muscle structure of chronic low back pain patients. Objectives. To analyze the effects of 3 months active therapy on gross back muscle size and muscle fiber type characteristics and their relationship to changes in muscle function. Summary of Background Data. Many studies have documented a diminished muscular performance capacity in cLBP patients, but few have supported this with evidence of alterations in either the macro- or microscopic structure of the paraspinal muscles. Investigations of the changes in muscle structure following active rehabilitation are even rarer. Methods. Assessments of trunk muscle cross-sectional area (using MRI), erector spinae fiber size/type distribution and pathology (percutaneous biopsy), and muscle function (see Part 1) were made in a group of 59 individuals with cLBP, who were participating in a randomized trial of active therapies for cLBP (physiotherapy, muscle training on devices, aerobics). Results. Fifty-three out of 59 patients (90%) completed the therapy. At baseline, significant correlations were observed between the size of the paraspinal muscles and isometric back extension strength (P =0.0001), and between the proportional area of the muscle occupied by each fiber type and the fatigability of the muscle (P =0.012). Following therapy, there were small (few percent) increases in trunk muscle size in the aerobics and physiotherapy groups and a similarly slight decrease in the devices group. Changes in erector spine size correlated only weakly and nonsignificantly with changes in back extension strength. There were no major changes in fiber type proportion or fiber size in any group following therapy. Conclusion. Three months active therapy is not sufficient to reverse the typical “glycolytic” profile of the muscles of cLBP patients or to effect major changes in backmuscle size. The alterations in muscle performance observed (increased strength and endurance; Part 1) werenot explainable on the basis of structural changes within the muscle.

Human α and β parvalbumins

alpha and beta parvalbumins are Ca(2+)-binding proteins of the EF-hand type. We determined the protein sequence of human brain alpha parvalbumin by mass spectrometry and cloned human beta parvalbumin (or oncomodulin) from genomic DNA and preterm placental cDNA. beta parvalbumin differs in 54 positions from alpha parvalbumin and lacks the C-terminal amino acid 109. From MS analyses of alpha and beta parvalbumins we conclude that parvalbumins generally lack posttranslational modifications. alpha and beta parvalbumins were differently expressed in human tissues when analyzed by immunoblotting and polymerase-chain-reaction techniques. Whereas alpha parvalbumin was found in a number of adult human tissues, beta parvalbumin was restricted to preterm placenta. The pattern of alpha parvalbumin expression also differs in man compared to other vertebrates. For example, in rat, alpha parvalbumin was found in extrafusal and intrafusal skeletal-muscle fibres whereas, in man, alpha parvalbumin was restricted to the muscle spindles. Different functions for alpha and beta parvalbumins are discussed.

Paraspinal muscle fibre type alterations associated with scoliosis: an old problem revisited with new evidence

Abstract To establish the extent to which the paraspinal muscles are affected in idiopathic scoliosis, samples from patients must be compared with controls of a similar gender and age. To date, insufficient control data has been available for these purposes. The aim of this study was to redress this tissue, in order to identify whether one side of the apex of the scoliotic curve showed greater muscular abnormalities than the other. Bilateral samples of the paraspinal muscles were obtained during surgery from 14 female scoliosis patients, at the apex of the scoliotic curve at T9–T11. Percutaneous muscle biopsy samples were obtained from nine female volunteers, on the left side of the spine at T10. Samples were prepared for routine histochemistry for the identification of muscle fibre types. Fibre size was measured using computerised image analysis. Compared with control muscle, there was a significantly lower proportion of type I (slow-twitch oxidative) fibres in the muscle on the concave side of the scoliotic curve, but no difference on the convex side. The proportion of type IIB (fast-twitch, glycolytic) fibres was higher on both sides of the curve compared with controls, with the effect being significantly more marked on the concave side. The percentage of type IIA (slow-twitch, oxidative-glycolytic) fibres did not differ between the groups, and neither did fibre size (although there was a tendency for the controls to have larger type IIA fibres than the patients). Collectively, the differences in fibre type size and distribution meant that on the concave side the relative area of the muscle occupied by type I fibres was smaller, and on both sides of the curve the relative area occupied by type IIB fibres was greater and by type IIA fibres smaller, in comparison with controls. In scoliosis, the spinal musculature is most affected on the concave side of the curve’s apex. The muscle adopts a ‘faster’, or more ‘glycolytic’ profile, which would be consistent with a reduced low-level tonic activity of the muscle, perhaps consequent to a local change in activity on this side of the spine following progression of the curve. Less marked changes, in the same direction, are also evident on the convex side; these may be the result of general disuse of the paraspinal muscles associated with the spinal deformity.

The sternomastoid muscle of the rat and its innervation. Muscle fiber composition, perikarya and axons of efferent and afferent neurons

SummarySeveral quantitative and qualitative parameters of the rat sternomastoid muscle and its innervation have been investigated. The sternomastoid muscle consists of two even macroscopically clearly distinguishable portions, a white and a red one, the latter occupying the deep medial section of the muscle.Correlating serial cross sections stained for alkali-stable ATP-ase and NADH-TR activity, 4 different muscle fiber types were found in the red zone (βR, αR, αI, αβW), 2 types in the white zone (αI, αβW). Mean diameters and percentages of muscle fiber types in the different parts of the muscle were determined. About 20 muscle spindles, preferentially located in the red part, were detected. The average size of motor units was calculated to be about 54.In the sternomastoid nerve, which originates from the accessory nerve (motor root) and from the cervical plexus (sensory root), electronmicroscopically a mean total of 558 nerve fibers was counted (47% myelinated, 53% unmyelinated). The diameter distribution of unmyelinated fibers reveals two distinct peaks in the sternomastoid nerve as well as in its roots. This indicates the existence of two different kinds of unmyelinated fibers.Using acetylcholinesterase (ACHE) histochemistry (Zenker and Hohberg, 1973) numbers and diameters of myelinated ACHE-positive (motor) and ACHE-negative (sensory) nerve fibers were determined. 53% of the myelinated fibers in the sternomastoid nerve were found to be motoric (65% α-motor, 35% γ-motor fibers).Using the HRP tracing technique the perikarya of the motor and sensory neuron pools were identified, counted, and their diameters determined. Motoneurons are localized from the transition zone brain stem/spinal cord to the third cervical segment of the spinal cord, lying dorsomedially in the ventral horn in the upper segments and shifting laterally in the caudal segments. The diameter distribution of motoneuronal perikarya is clearly bimodal corresponding to α-and γ-neurons. Perikarya of primary afferent neurons are located in spinal ganglia C2-C4. Their diameter distribution was found to be trimodal.The aim of the study was to give a complex morphological description of one nerve muscle system and to compare some parameters with those of other systems.

Variable pH dependence of the myosin-ATPase in different muscles of the rat

SummaryFor the histochemical demonstration of the Myosin-ATPase (EC 3.6.1.3) the pH of both the preincubation and the incubation medium was varied in steps of 1 within a small range: 10.2 to 10.5 and 9.3 to 9.6, respectively. The optimum combinations of both pH values, defined as the ones providing most consistent contrast among the three major types of muscle fibers were determined in 9 different muscles of the rat. The spectrum of optimum combinations differs considerably from muscle to muscle. The reduction of the incubation pH by only 0.1 may drastically change the staining pattern. This probably reflects the unspecifity of the histochemical procedure as well as the plasticity of the ATPase systems. To cope with the lability of the myosin-ATPase the optimum pH values of both media should be determined for each muscle separately.