The effect of chronic low back pain on size and contraction of the lumbar multifidus muscle

Decreases in the size of the multifidus muscle have been consistently documented in people with low back pain. Recently, ultrasound imaging techniques have been used to measure contraction size of the multifidus muscle, via comparison of the thickness of the muscle at rest and on contraction. The aim of this study was to compare both the size (cross-sectional area, CSA) and the ability to voluntarily perform an isometric contraction of the multifidus muscle at four vertebral levels in 34 subjects with and without chronic low back pain (CLBP). Ultrasound imaging was used for assessments, conducted by independent examiners. Results showed a significantly smaller CSA of the multifidus muscle for the subjects in the CLBP group compared with subjects from the healthy group at the L5 vertebral level (F = 29.1, p = 0.001) and a significantly smaller percent thickness contraction for subjects of the CLBP group at the same vertebral level (F = 6.6, p = 0.02). This result was not present at other vertebral levels (p > 0.05). The results of this study support previous findings that the pattern of multifidus muscle atrophy in CLBP patients is localized rather than generalized but also provided evidence of a corresponding reduced ability to voluntarily contract the atrophied muscle.     

The lumbar multifidus muscle and patterns of pain

This paper describes the patterns of pain induced by injecting hypertonic saline into the lumbar multifidus muscle opposite the L5 spinous process in 15 healthy adult volunteers. All subjects experienced local pain while referred pain was reported by 13 subjects in one of two regions of the thigh; anterior (n=5) or posterior (n=8). These results confirm that the multifidus muscle may be a source of local and referred pain. Comparison of these maps with pain maps following stimulation of the L4 medial dorsal rami and L4-5 interspinous ligaments shows that pain arising from the band of multifidus innervated by the L4 dorsal ramus has a segmental distribution. In addition patterns of pain arising from multifidus clearly overlap those reported for other lumbar structures. These findings highlight the difficulty of using pain distribution to accurately identify specific lumbar structures as the source of pain.     

Measurement of lumbar multifidus muscle contraction with rehabilitative ultrasound imaging

Rehabilitative Ultrasound Imaging (RUSI) has been validated as a noninvasive method to measure activation of selected muscles. The purpose of this study was to determine the relationship between muscle thickness change, as measured by ultrasonography, and electromyography (EMG) activity of the lumbar multifidus (LM) muscle in normal subjects. Bipolar fine wire electrodes were inserted into the LM at the L4 level of five subjects. Simultaneous EMG and RUSI data (muscle thickness) were collected while subjects performed increasingly demanding postural response tasks thought to activate the LM muscle. To determine the relationship between muscle thickness change and EMG activity, the normalized EMG data were correlated to normalized RUSI data. To determine if the tasks increased the demand on the LM, the mean EMG data were compared over each of the four tasks. Muscle thickness change as measured by RUSI was highly correlated with EMG activity of LM in asymptomatic subjects (r=.79,P<.001). Mean EMG data showed increasing levels of activation across tasks (19-34% of maximum voluntary isometric contraction (MVIC)). The results of the repeated measures ANOVA demonstrated theses differences were significant (F(3,12)=25.39,P<.001). Measurement of muscle thickness change utilizing RUSI is a valid and potentially useful method to measure activation of the LM muscle in a narrow range (19-34% of MVIC) in an asymptomatic population.     

Reliability of B-mode ultrasonography to measure lumbar multifidus muscle dimensions in patients with unilateral lumbar disc herniation

ObjectivesTo evaluate Ultrasound Imaging (USI) reliability for measurement of lumbar multifidus (LMF) muscle thickness and cross sectional area (CSA) at rest and during contraction in patients with unilateral lumbar disc herniation.SettingLaboratory.DesignReliability Study.ParticipantsThirty patients, aged 25–50 years (37.55 ± 9.55), with unilateral L4-L5 lumbar disc herniation participated in this study.Main outcome measuresThickness and CSA of LMF were measured using B-mode ultrasound by two raters in prone position.ResultsSame day and multiple day inter-rater and same day intra-rater reliability showed good to excellent reliability (intraclass correlation coefficients ranged from 0.70 to 0.91). Also standard error of measurement and minimal detectable change for USI reliabilities ranged from 0.06 to 0.57 and 0.16 to 1.31, respectively.ConclusionsReliability of USI for measurements of LMF muscle thickness and CSA was high, and consistent with previous studies conducted on reliability of USI to measure LMF dimensions in other populations.     

Ultrasound transducer shape has no effect on measurements of lumbar multifidus muscle size

ObjectiveEvidence is currently lacking for guidance on ultrasound transducer configuration (shape) when imaging muscle to measure its size. This study compared measurements made of lumbar multifidus on images obtained using curvilinear and linear transducers.MethodFifteen asymptomatic males (aged 21–32 years) had their right lumbar multifidus imaged at L3. Two transverse images were taken with two transducers (5 MHz curvilinear and 6 MHz linear), and linear and cross-sectional area (CSA) measurements were made off-line. Reliability of image interpretation was shown using intra-class correlation coefficients (0.78–0.99). Muscle measurements were compared between transducers using Bland and Altman plots and paired t-tests. Relationships between CSA and linear measurements were examined using Pearson's Correlation Coefficients.ResultsThere were no significant differences (p > 0.05) in the measurements of the two transducers. Thickness and CSA measurements had small differences between transducers, with mean differences of 0.01 cm (SDdiff = 0.21 cm) and 0.03 cm² (SDdiff = 0.58 cm²) respectively. Width measures had a mean difference of 0.14 cm, with the linear transducer giving larger measures. Significant correlations (p < 0.001) were found between all linear measures and CSA, with both transducers (r = 0.78–0.89).ConclusionMeasurements of multifidus at L3 were not influenced by the configuration of transducers of similar frequency. For the purposes of image interpretation, the curvilinear transducer produced better definition of the lateral muscle border, suggesting it as the preferable transducer for imaging lumbar multifidus.     

The biomechanics of the lumbar multifidus

The possible actions of the lumbar multifidus were determined by plotting the points of attachment and orientation of each of its component fascicles on radiographs of 5 cadavers and 21 living subjects. Subsequent analysis revealed that the principal action of multifidus is posterior sagittal rotation (extension without posterior translation) of the lumbar vertebrae. It has no translatory action. Any axial rotation exerted by the lumbar multifidus is only a minor, secondary action which must be coupled with posterior sagittal rotation. This extension balances the flexion moment generated by the abdominal muscles which rotate the trunk. The constancy of the sites of attachment of the multifidus allows each of its fascicles to be plotted accurately on radiographs or computer diagrams which can be used to produce highly detailed analyses or models of the forces exerted by the multifidus on the lumbar spine.     

The effect of experimental muscle pain on the background electrical brain activity.

The purpose of this project was to investigate whether specific effects in the background activity of the brain associated with the experience of pain can be depicted by means of quantitative electroencephalography (EEG). Lasting pain was induced by intramuscular infusion of hypertonic saline. The infusion was titrated to maintain pain for a sufficient time to obtain enough data for meaningful analysis. In a first study on 12 subjects, using a single, blind, repeated measures design with randomization of the administration of isotonic (0.9%) and hypertonic (5%) saline, and with subjects unaware of the fact that one substance was isotonic saline, a statistically significant pain response could be attributed to the administration of hypertonic saline. In a second study on 19 subjects, again using a randomized repeated measures design, topographic EEG measures were examined with respect to experimentally induced pain and pain from memory. Prior to each of these experimental stages, baseline recordings were obtained to satisfy the requirement of the crossover design. In addition to the common frequency bands used in EEG, we also obtained data in the frequency range of 35-100 Hz. The short-term variability of the selected EEG measures and their suitability as a sample estimate were assessed by computing the coefficient of variation from all selected epochs of a given subject at baseline. When compared to baseline, spectral analyzed EEG measures during experimental pain demonstrated statistically significant increases in the beta and 35-100 Hz frequency ranges, most notably at the temporal recording sites. There was no statistically significant difference between the EEG measures for (1) experimental pain vs. pain from memory, and (2) the 2 baseline recordings. The great variability in the topographical aspect of the between-subject response was interpreted as being strongly suggestive of the contamination of EEG measures by phenomena attributed to the jaw, facial and scalp musculature. In fact, Pearson correlation coefficients, as high as 0.92, were found between measures in the frequency band of 35-100 Hz and the beta frequency range. The unexplained variance in the heightened beta cortical power density can be attributed to the vigilance scanning of pain processes. Due to the fact that the statistically significant effect of pain on the topographic EEG measures were not different from imagined pain, we concluded that these effects are non-specific for pain.     

推拿手法对腰椎髓核内压影响的实验研究

目的：比较临床上几种常用的腰部推拿手法对腰椎髓核内压力的影响。方法：用生物材料实验机对新鲜尸体腰椎标本施以计算机定量模拟的不同手法,观察髓核内压力变化情况。结果：模拟斜扳手法和坐位旋转手法,椎间盘髓核内压力均升高,模拟牵扳手法髓核内压下降,结论：牵手法治疗腰椎间盘突出症时较为安全。     

The relationship of transversus abdominis and lumbar multifidus clinical muscle tests in patients with chronic low back pain

Introduction

Previous research of transversus abdominis (TrA) and multifidus muscle function in the presence of chronic low back pain (LBP) has investigated these muscles in isolation. In clinical practice, it is assumed that a relationship exists between these muscles and so they are often assessed and rehabilitated together. However, no studies have tested or documented this association. This study aimed to examine the relationships between clinical muscle testing and other measures taken in the course of a clinical assessment at a back clinic.

Methods

This retrospective chart audit examined the files of 82 patients (40 Males, 42 Females) for results of clinical tests of TrA and multifidus muscle contraction, multifidus muscle size measurements and other clinical measures such as distribution of pain and pain on manual examination.

Results

The ability to contract multifidus was related to the ability to contract TrA with the odds of a good contraction of multifidus being 4.5 times higher for patients who had a good contraction of TrA. A poor ability to contract multifidus was related to poor TrA contraction. Patients with unilateral LBP had more multifidus muscle asymmetry (11.6%) than those with bilateral/central pain (0.01%) and had a poor multifidus contraction on the affected side (p < 0.01). No other significant relationships were found.

Discussion & conclusion

Current clinical practice of assessment and rehabilitation of both TrA and multifidus muscles in patients with chronic LBP is supported by the findings of this study. Future studies may investigate if a neurophysiological relationship exists between these muscles.     

The morphology of the human lumbar multifidus

Dissection studies revealed that the fibres of the lumbar multifidus are divided by distinct cleavage planes into five bands. Each band arises from a lumbar spinous process, and is innervated unisegmentally. The lumbar multifidus is therefore composed of five myotomes arranged such that the fibres that move a particular segment are innervated by the nerve of that segment. Target points are described that enable electromyography to be performed on paraspinal muscles of known unisegmental innervation.     

Intermittent isometric fatigue study of the lumbar multifidus muscle in four-point kneeling: an intra-rater reliability investigation.

Back muscle endurance is considered important in low back pain (LBP) rehabilitation. Specific training of multifidus may also be necessary to restore normal low back function. The reliability of surface electromyogram (EMG) to assess endurance of the multifidus muscle during intermittent isometric exercise was evaluated. Multifidus endurance was monitored in the four-point kneeling exercise position using the power spectral analysis method. Twenty healthy volunteers were tested on three separate occasions. Subjects performed repeat 10 s high-intensity voluntary contractions of multifidus for 3 min. The median frequency (MF) and the integrated-rectified (I-R) EMG signal displayed the fatigue pattern of multifidus. Intraclass correlation coefficients indicated fair-good reproducibility for MF (0.48-0.67) but poor reliability for IR-EMG. In conclusion, problems concerning functional testing protocols for the back muscles remain and careful development is necessary for more realistic rehabilitation monitoring.     

Effects of tactile feedback on lumbar multifidus muscle activity in asymptomatic healthy adults and patients with low back pain

Background

Reduced lumbar multifidus (LM) muscle contraction has been observed in patients with low back pain (LBP). Clinicians often use various strategies to ensure LM activation, including tactile feedback and verbal instruction. However, the effects of tactile feedback on muscle activation have not been studied previously. Therefore, the purpose of this study was to investigate whether or not tactile feedback would increase LM muscle activity in adults with and without LBP.

The effect of glycerol on autotomy. An experimental model of neuralgia pain

Autotomy in nerve injured rats has been put forward as an animal model in a broad range of chronic neuralgic pain. We have examined the effect of glycerol, a new and promising therapeutic agent for trigeminal neuralgia, on this animal model. A single dose of glycerol, alcohol or saline was injected directly into experimental sciatic nerve neuromas in rats via a chronically implanted cannula. Injections were made either at the time of nerve injury or 2 weeks afterwards. Both forms of glycerol treatment caused a significant reduction in autotomy behavior relative to saline. Alcohol also suppressed autotomy, but it was less effective than glycerol.     

Experimentally induced pain alters the EMG activity of the lumbar multifidus in asymptomatic subjects

Lumbar musculature plays an important role in stabilization during functional movements such as walking, bending and overhead activities. Current research has focused on the lumbar multifidus (LM) muscle to determine if altered activity of the LM may contribute to low back pain (LBP). Therefore, the purpose of this study was to determine whether experimentally induced LBP affects deep LM muscle activity during functionally oriented tasks, weight shifting and upper extremity lifting. Intramuscular electromyography (EMG) activity of the LM at L4 was measured in 17 healthy adults during a dominant side shoulder flexion and extension task and during a staggered-stance weight shift task. Data were collected at baseline, after pain was induced with hypertonic saline and after the pain had subsided. Comparisons of within-subjects effects were performed with the use of a two-way repeated-measure ANOVA. A significantly higher magnitude of activity was found in the induced pain condition as compared to the baseline condition for the shoulder extension phase of the upper extremity task (p = 0.04). During forward weight shifting, lower values in both the induced pain (p = 0.02) and the recovery conditions (p = 0.01) were measured. During backward weight shifting, lower values were measured during the recovery condition as compared to baseline (p = 0.03). Across trials and subjects the EMG amplitudes were increased during the extension phase of the upper extremity task and decreased during the weight shifting task. These results suggest that the LM does not respond to induced pain in the same manner during different phases of functionally oriented tasks.     

核心肌群康复训练联合疼痛护理对腰椎间盘突出症患者疼痛及腰椎功能的影响

目的 探讨针对性核心肌群康复训练联合疼痛护理对腰椎间盘突出症患者疼痛及腰椎功能的影响。方法 选择2018年5月—2020年5月收治的腰椎间盘突出症患者82例,采用随机数字表法将其分成对照组和观察组,每组41例。对照组采取常规专科护理,观察组在此基础上采取针对性核心肌群康复训练联合疼痛护理,持续4周。比较2组腰背肌力、疼痛及腰椎功能。结果 干预后,观察组腰背伸峰力高于对照组（t=3.340,P=0.001）;腰背屈伸低于对照组（t=3.326,P=0.001）;疼痛视觉模拟评分（visual analogue scale,VAS）、Oswestry功能障碍指数（Oswestry disability index,ODI）评分均低于对照组（t=4.946,P<0.001;t=6.789,P<0.001）,日本骨科协会评估治疗评分（assessment of treatment scores by the Japanese orthopaedic association,JOA）高于对照组（t=7.244,P<0.001）。结论 针对性核心肌群康复训练联合疼痛护理能够减轻腰...     

Increased intramuscular fatty infiltration without differences in lumbar muscle cross-sectional area during remission of unilateral recurrent low back pain

Lumbar muscle degeneration is a common feature in non-specific low back pain (LBP). It is hypothesized that degenerated muscles might compromise spinal stability and lead to further injury/pain. However, little is known about lumbar muscle morphometry after resolution of LBP. Therefore, this study investigated the extent of lumbar muscle atrophy and fatty infiltration in individuals who are at risk for a recurrence of LBP. Thirteen participants in remission of unilateral recurrent LBP were compared to 13 healthy controls, comparable for age, weight, length and level of physical activity. Total, lean muscle and fat cross-sectional area (CSA) of lumbar multifidus (MF), erector spinae (ES) and psoas (PS) were investigated on T1-weighted Magnetic Resonance Imaging (MRI), bilaterally and at 3 lumbar levels (L3 upper, L4 upper and L4 lower endplate). In addition, a muscle-fat-index (MFI) was calculated reflecting the amount of fatty infiltration in lean muscle tissue. No significant differences for total, lean muscle and fat CSA were found between people in remission of recurrent LBP and the control group. Conversely, MFI was increased bilaterally at the 2 lowest lumbar levels. There were no differences between the previously painful and non-painful side of the LBP group for any of the parameters. These results show a generalized increase in intramuscular fatty infiltration in lean muscle tissue in the absence of macroscopical signs of muscle degeneration after resolution of LBP. These findings reflect a decreased muscle quality, but not quantity, and might indicate a pathophysiological mechanism contributing to recurrence of LBP.     

Effects of different verbal instructions on change of lumbar multifidus muscle thickness in asymptomatic adults and in patients with low back pain

Background: Spinal stabilisation exercise has been shown to be effective in the rehabilitation of low back pain (LBP). Due to the isometric nature of spinal stabilisation exercise, manual therapists use various verbal instructions to elicit lumbar multifidus muscle contraction.

Objectives: The purpose of this study was to assess whether or not three verbal instructions would alter muscle thickness of the lumbar multifidus muscle differently in asymptomatic individuals and patients with LBP.

Methods: Three verbal instructions were selected for this study: (1) swell the muscle underneath the transducer, (2) draw your belly button in towards your spinal column and (3) think about tilting your pelvis but without really doing it. Lumbar multifidus muscle thickness was determined using parasagittal ultrasound (US) imaging. Measurements of muscle thickness were collected at rest and during verbal instructions from 21 asymptomatic adults and 21 patients with LBP. Percent changes of muscle thickness during contraction and at rest were compared between groups and across verbal instructions.

Results: ANOVA results showed no significant interaction for both L4-5 and L5-S1, but a significant main effect of verbal instruction (P?=?0.049) at L4-5.Post hoc analysis showed a greater increase with verbal instruction #3 than verbal instruction #2 (P?=?0.009). There was no significant main effect of group at either segment.

Discussion: The results of the study suggest that both groups responded similarly to the three verbal instructions. Verbal instructions may increase lumbar multifidus muscle thickness by different amounts at L4-5, but by the same amount at L5-S1.