Ultrasound imaging of lumbar multifidus muscle: normal reference ranges for measurements and practical guidance on the technique

This cross-sectional, prospective study aimed to produce normal reference data for measurements of the lumbar multifidus muscle. A total of 120 subjects, 68 females (aged 20-64 years) and 52 males (20-69 years) were studied. Bilateral transverse ultrasound images were made of multifidus at the fourth and fifth lumbar vertebrae (L4 & L5). Cross-sectional area (CSA, cm(2)) and linear dimensions (AP, anteroposterior; Lat, lateral) were measured and the latter expressed as a ratio (AP/Lat) to reflect shape. Relationships between CSA and anthropometric measures were examined. Multifidus CSA was larger in males (P<0.001) and age had no effect. The CSA was larger at L5 than L4 (P<0.001) and highly correlated between the two levels (males r=0.82, females 0.80). Differences in muscle shape were observed for gender, age and vertebral level. Between-side symmetry was high for size but not shape (CSA <10% difference). Linear measurements multiplied (APxLat) correlated highly with CSA (all groups r0.94, P<0.0001). The AP dimension was also acceptably predictive of CSA at L4 (r0.79). There were no clinically useful correlations between CSA and anthropometric measures. These findings provide normal references ranges for objective assessment of lumbar multifidus. This paper also addresses specific practical issues when scanning multifidus.     

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.     

不同病程腰椎间盘突出症患者腰部多裂肌横截面面积研究

目的：研究不同时期腰椎间盘突出患者腰部多裂肌横截面面积（CSA）,评估多裂肌萎缩情况。方法55例腰椎间盘突出患者,按发病时间分为急性期15例、亚急性期10例、慢性期30例,使用实时定量超声测量腰4/5水平椎间盘突出累及侧及非累及侧在俯卧休息位下腰部多裂肌CSA。结果男性、女性及总体累及侧多裂肌CSA的急性期与慢性期比较,差异均有统计学意义（t分别=4.15、3.54、4.11,P均＜0.05）,女性非累及侧多裂肌CSA急性期与慢性期比较,差异有统计学意义（t=2.40,P＜0.05）。男性与女性腰部累及侧、非累及侧各期多裂肌CSA比较,差异均有统计学意义（t分别=5.72、2.88、2.20;5.70、3.35、2.79,P均＜0.05）。在亚急性期,男性累及侧多裂肌CSA较非累及侧小;在慢性期,男性和女性的累及侧多裂肌CSA均较非累及侧小;且总体累及侧多裂肌CSA也较非累及侧小,差异均有统计学意义（t分别=3.85、2.73、4.66、14.11,P均＜0.05）。在慢性期,女性和男性腰部多裂肌累及侧CSA与非累及侧CSA之间不对称差异值（CSA%）分别为（12.16±10.10）%、（16.45±7.20）%,较急性期同性别组CSA%值均大,差异有统计学意义（t=4.68、2.44,P均＜0.05）。结论定量超声可以用于评估腰部多裂肌形态改变;椎间盘突出病程不足3月,腰部多裂肌萎缩可不明显;反复腰痛大于3个月的患者,多裂肌在双侧横截面面积均减小,以累及侧萎缩较为明显,双侧多裂肌横截面面积呈不对称性表现。     

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.     

The effect of unilateral muscle pain on recruitment of the lumbar multifidus during automatic contraction. An experimental pain study

Changes in control of the multifidus muscle are a likely contributor to low back pain (LBP), however, the underlying mechanisms of these changes are not well understood. To date it remains uncertain if pain has a selective effect on the multifidus muscles, in line with the observations of the selective changes in structure in acute LBP, or a more generalized effect.The objective of this study is to help to elucidate whether acute unilateral muscle pain alters the activation of the multifidus specific at the level and side of the pain or has a more widespread effect.An experimental pain protocol using hypertonic saline was applied to induce unilateral low back muscle pain. Automatic activity of the multifidus muscle during arm lifts was evaluated with dynamic ultrasound measurement, by assessing muscle thickness change during contraction. Multifidus activity of 15 healthy subjects was compared in a non-pain and in a pain condition, at different spinal levels (L3–L4–L5) and at both body sides.Unilateral induced pain at one segmental level reduced muscle thickness increase during contraction, at both body sides and at different lumbar levels.These results do suggest that unilateral pain may have a more widespread effect on multifidus muscle recruitment, affecting the left and right muscles, at different lumbar levels.     

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.     

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.     

Moderate normovolaemic haemodilution increases regional myocardial blood flow but has no effect on experimental infarct size

Regional myocardial blood flow was measured with radioactive microspheres before and 1, 3, 6, and 12 h after occlusion of the left anterior descending coronary artery (LAD) in anaesthetized cats. In one group of cats, 1 h after LAD occlusion, moderate normovolaemic haemodilution was started with a dextran 40 solution, which reduced the haematocrit by 20-25% throughout the rest of the experiment. In the other group, the haematocrit was kept at the original level. Infarct size was measured planimetrically 12 h after the coronary ligation, using the tetrazolium staining technique for disclosing the ischaemic myocardium. Haemodilution increased blood flow in the non-ischaemic myocardium and in the so-called 'border zone' comprising both normal, and ischaemic tissue. However, in the severely ischaemic myocardium dependent on collateral blood flow, where there was no admixture of non-ischaemic myocardium, the blood perfusion was not significantly affected by the haemodilution. After 12 h of ischaemia the infarct size in the control group was fully comparable with that in the haemodiluted group: 28 +/- 3 and 27 +/- 4 (percentage of the left ventricle, mean +/- SEM), respectively.     

Recovery of the lumbar multifidus muscle size in chronic low back pain patients by strengthening hip abductors: A randomized clinical trial

IntroductionDecrease in cross-sectional thickness of lumbar multifidus (MF) muscles during prolonged low back pain episodes commonly occurs. Restoration of the MF muscle size can be an effective way of treating chronic low back pain (CLBP) patients. Traditionally, clinicians apply muscle stabilization exercises for these patients. Recent studies support the need for active strengthening exercises for treatment of the CLBP patients.ObjectiveThe MF muscles provide lumbar stability, and therefore we hypothesized that strengthening of these muscles can be more effective than the MF muscle stabilization exercises in restoration of the muscle size.DesignStudy design was a randomized allocation control trial with two groups of adult female CLBP patients (n = 12 each; age range of 20–45). Patients in the control group underwent stabilization exercises and the patients in the intervention group underwent the hip abductor strengthening exercises.SettingFor all subjects of each group, the trials continued in 24 sessions distributed over 8 weeks and the MF muscles were measured in the beginning of the first session and one week after completion of the last session.Main outcome measuresStatistical significance (p-value) of the change in the average MF muscle thickness, pain, and disability scores along with for each group were estimated.ResultsBoth regimens of exercises can significantly decrease the pain and disability: average pain and disability reductions of 46% (p-value of 0.001) and 33% (p-value of 0.02) via stabilization versus average pain and disability reductions of 65% (p-value of 0.001) and 59% (p-value of 0.001) via hip abductor strengthening. However, the hip abductor strengthening is the sole statistically significant exercise regimen (p-value of 0.014 vs 0.94) for increasing the MF muscle size.ConclusionReplacement of the traditional stabilization exercises with the hip abductor strengthening exercises for effective treatment of female adults with CLBP is recommended.     

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.     

Intravenous saline has no effect on blood ethanol clearance

For patients presenting to emergency departments with ethanol intoxication, intravenous (i.v.) fluids are initiated for varied reasons. This investigation determined the effect of i.v. fluid therapy on the rate of blood ethanol clearance in such patients. Volunteers received a predetermined dose of ethanol on two separate occasions. On the second occasion, volunteers rapidly received a liter of i.v. saline directly following ethanol ingestion. At intervals on both occasions, blood ethanol levels were estimated using a breath analyzer. Using linear regression analysis, no difference was found in rates of alcohol clearance with or without i.v. fluid intervention. The common rate of clearance between both groups was 15 mg/dL/h (95% CI 12 to 18). We conclude that i.v. fluid therapy does not accelerate ethanol clearance in intoxicated patients. While such therapy may be justified for other reasons, practitioners are cautioned against initiating fluids in such patients solely to expedite ethanol elimination.     

Teriparatide has no effect on the calcium-mediated pharmacodynamics of digoxin

BACKGROUND: Teriparatide (recombinant human parathyroid hormone [1-34]) stimulates bone formation and causes small transient increases in serum calcium concentration. We assessed whether teriparatide causes a change in digoxin pharmacodynamic effects by measuring systolic time intervals and heart rate. METHODS: Measurements were made by echocardiographic Doppler that examined 3 systolic time intervals, as follows: QS(2) (time from Q wave on electrocardiogram to the closure of the aortic valve), left ventricular ejection time, and pre-ejection period, all corrected for changes in heart rate. Fifteen healthy subjects (2 men and 13 women) were administered a single subcutaneous teriparatide dose (20 microg) on day 1 and then equilibrated on a daily oral dose of digoxin for 15 days. Subcutaneous placebo and teriparatide, 20 microg, were given in a randomized crossover design with the 14th (day 15) and 15th (day 16) digoxin doses. Serial systolic time interval and heart rate measurements were obtained on days 1, 15, and 16. RESULTS: After subjects were dosed to steady state with digoxin, there were statistically significant reductions in QS(2) corrected for heart rate (QS(2)c) of 23 to 25 ms and heart rate of 4 to 6 beats/min. However, there was no difference between treatment with digoxin plus placebo versus digoxin plus teriparatide. The study was powered to find a difference in QS(2)c as small as 6 ms (alpha =.05, beta =.2). CONCLUSION: Teriparatide, 20 microg subcutaneously, does not alter the cardiac effect of digoxin.     

Ultrasound assessment of hamstring muscle size using posterior thigh muscle thickness

Several studies have investigated the relationship between ultrasound‐measured muscle thickness (MT) and individual muscle cross‐sectional area (CSA) and muscle volume (MV) in extremity and trunk muscles; however, the hamstring muscle has not been studied. The purpose of this study was to examine the relationship between posterior thigh MT by ultrasound and the muscle CSA and MV of the hamstring obtained by magnetic resonance imaging (MRI). Ten young women aged 20–31 had MT measured by ultrasound at three sites on the medial anterior (50% of thigh length; TL) and posterior (50% and 70% of TL) aspects of the thigh. On the same day, a series of continuous muscle CSA along the thigh was measured by MRI. In each slice, the anatomical CSA of the hamstring (biceps femoris, semitendinosus and semimembranosus) and quadriceps muscle was analysed, and the CSAs at 50% and 70% of TL and maximal CSA of the hamstring (CSA_max) were determined. MV was calculated by multiplying CSA by slice thickness. A significant correlation was observed between posterior 50% MT and 50% hamstring CSA (r = 0·848, P = 0·002) and between posterior 70% MT and 70% hamstring CSA (r = 0·679, P = 0·031). Posterior 50% MT (r = 0·732, P = 0·016) and 50% MTxTL (r = 0·873, P = 0·001) were also correlated to hamstring MV. Anterior:posterior 50% thigh MT ratio was correlated to MV ratio of quadriceps and hamstring muscles (r = 0·803, P = 0·005). Our results suggest that posterior thigh MT reflects hamstring muscle CSA and MV. The anterior:posterior MT ratio may serve as a surrogate for MV ratio of quadriceps and hamstring.     

Short-term augmented calcium intake has no effect on sodium homeostasis

To test the hypothesis that the supplementation of dietary calcium intake influences sodium homeostasis, the renin-angiotensin system, and sympathetic nervous system in a manner that might evoke a decrease in arterial blood pressure, we gave 16 participants (eight normal and eight with hypertension) placebo for 8 days, followed by 500 mg elemental calcium as the carbonate salt twice a day for 8 days. The same diet was prepared for each meal for the entire study. Sodium intake was fixed for each participant and averaged 150 mEq/day. All urine was collected every day. Blood was drawn at the end of the placebo and calcium periods for determinations of plasma renin, aldosterone, and norepinephrine values. Calcium supplementation increased urinary calcium excretion significantly in both groups. However, calcium supplementation failed to influence sodium or potassium excretion, serum electrolytes, total serum calcium, renin, aldosterone, or norepinephrine levels, or heart rate. Systolic and diastolic blood pressure were not influenced in normal subjects, but in patients with hypertension the supine systolic blood pressure decreased significantly. We conclude that blood pressure lowering effects of calcium, should they occur, are not likely the result of augmented urinary sodium excretion or of straight-forward influences on the renin-angiotensin system or sympathetic nervous system.