Context: A neuromuscular relationship exists between the lumbar extensor and quadriceps muscles during fatiguing exercise. However, this relationship may be different for persons with low back pain (LBP).
Objective: To compare quadriceps inhibition after isometric, fatiguing lumbar extension exercise between persons with a history of LBP and control subjects.
Design: A 2 × 3 factorial, repeated-measures, time-series design with independent variables of group (persons with a history of LBP, controls) and time (baseline, postexercise set 1, postexercise set 2).
Setting: University research laboratory.
Patients or Other Participants: Twenty-five subjects with a history of LBP were matched by sex, height, and mass to 25 healthy control subjects.
Intervention(s): Electromyography median frequency indexed lumbar paraspinal muscular fatigue while subjects performed 2 sets of isometric lumbar extension exercise. Subjects exercised until a 15% downward shift in median frequency for the first set and a 25% shift for the second set were demonstrated.
Main Outcome Measure(s): Knee extension force was measured while subjects performed an isometric maximal quadriceps contraction. During this maximal effort, a percutaneous electric stimulus was applied to the quadriceps, causing a transient, supramaximal increase in force output. We used the ratio between the 2 forces to estimate quadriceps inhibition. Quadriceps electromyographic activity was recorded during the maximal contractions to compare median frequencies over time.
Results: Both groups exhibited significantly increased quadriceps inhibition after the first (12.6% ± 10.0%,
P < .001) and second (15.2% ± 9.7%,
P < .001) exercise sets compared with baseline (9.6% ± 9.3%). However, quadriceps inhibition was not different between groups.
Conclusions: Persons with a history of LBP do not appear to be any more or less vulnerable to quadriceps inhibition after fatiguing lumbar extension exercise.
superimposed burst technique; neuromuscular activity; knee
Isolated lumbar paraspinal muscle fatigue causes lower extremity and postural control deficits.
To describe the change in body position during gait after fatiguing lumbar extension exercises in persons with recurrent episodes of low back pain compared with healthy controls.
Motion analysis laboratory.
Patients or Other Participants:
Twenty-five recreationally active participants with a history of recurrent episodes of low back pain, matched by sex, height, and mass with 25 healthy controls.
We measured 3-dimensional lower extremity and trunk kinematics before and after fatiguing isometric lumbar paraspinal exercise.
Main Outcome Measure(s):
Measurements were taken while participants jogged on a custom-built treadmill surrounded by a 10-camera motion analysis system.
Group-by-time interactions were observed for lumbar lordosis and trunk angles (P < .05). A reduced lumbar spine extension angle was noted, reflecting a loss of lordosis and an increase in trunk flexion angle, indicating increased forward trunk lean, in healthy controls after fatiguing lumbar extension exercise. In contrast, persons with a history of recurrent low back pain exhibited a slight increase in spine extension, indicating a slightly more lordotic position of the lumbar spine, and a decrease in trunk flexion angles after fatiguing exercise. Regardless of group, participants experienced, on average, greater peak hip extension after lumbar paraspinal fatigue.
Small differences in response may represent a necessary adaptation used by persons with recurrent low back pain to preserve gait function by stabilizing the spine and preventing inappropriate trunk and lumbar spine positioning.
gait analysis; spine
The purpose of this study was to determine the contribution of hamstrings and quadriceps fatigue to quadriceps inhibition following lumbar extension exercise. Regression models were calculated consisting of the outcome variable: quadriceps inhibition and predictor variables: change in EMG median frequency in the quadriceps and hamstrings during lumbar fatiguing exercise. Twenty-five subjects with a history of low back pain were matched by gender, height and mass to 25 healthy controls. Subjects performed two sets of fatiguing isometric lumbar extension exercise until mild (set 1) and moderate (set 2) fatigue of the lumbar paraspinals. Quadriceps and hamstring EMG median frequency were measured while subjects performed fatiguing exercise. A burst of electrical stimuli was superimposed while subjects performed an isometric maximal quadriceps contraction to estimate quadriceps inhibition after each exercise set. Results indicate the change in hamstring median frequency explained variance in quadriceps inhibition following the exercise sets in the history of low back pain group only. Change in quadriceps median frequency explained variance in quadriceps inhibition following the first exercise set in the control group only. In conclusion, persons with a history of low back pain whose quadriceps become inhibited following lumbar paraspinal exercise may be adapting to the fatigue by using their hamstring muscles more than controls.
Key PointsA neuromuscular relationship between the lumbar paraspinals and quadriceps while performing lumbar extension exercise may be influenced by hamstring muscle fatigue.QI following lumbar extension exercise in persons with a history of LBP group may involve significant contribution from the hamstring muscle group.More hamstring muscle contribution may be a necessary adaptation in the history of LBP group due to weaker and more fatigable lumbar extensors.
Superimposed burst technique; electromyography; spectral median frequency; correlation and regression; low back pain
Findings on imaging of noncontractile anatomic abnormalities and the intensity of low back pain have weak associations because of false-positive rates among asymptomatic individuals. This association might be stronger for contractile tissues.
The purpose of this study was to examine the relationship between location and reports of pain intensity in the low back and exercise-induced muscle damage to the lumbar paraspinal muscles.
Nondiagnostic observational study in a laboratory setting.
Delayed onset muscle soreness was induced in the low back of healthy pain-free volunteers. Measures of pain intensity (100-mm visual analog scale [VAS]) and location (area on the pain diagram) were taken before and 48 hours after exercise. Muscle damage was quantified using mechanical pain thresholds, motor performance deficits, and transverse relaxation time (T2)–weighted magnetic resonance imaging (MRI). Changes pre- to postexercise in signal intensity on T2-weighted imaging within the erector spinae, pain intensity, pain area, mechanical pain threshold, and isometric torque were assessed using paired t tests. Bivariate correlations were conducted to assess associations among muscle damage, pain intensity, and pain drawing area.
Twenty participants volunteered (11 women; average age, 22.3 years; average body mass index, 23.5) for study participation. Reports of pain intensity at 48 hours ranged from 0 to 59 mm on the VAS. Muscle damage was confirmed by reductions in mechanical threshold (p=.011) and motor performance (p<.001) and by changes in T2-weighted MRI (p=.007). This study was powered to find an association of at least r=0.5 to be statistically significant. Correlations of continuous variables revealed no significant correlations between pain intensity and measures of muscle damage (ranging between −0.075 and 0.151). There was a significant association between the remaining torque deficit at 48 hours and pain area.
The results of this study indicate that there was no association between the magnitude of muscle damage in the lumbar erector spinae and reported pain intensity in the low back. In future studies, larger cohorts may report statistically significant associations, but our data suggest that there will be low magnitude potentially indicating limited clinical relevance.
Spinal disorders; Imaging; Referred pain
Paraspinal muscle fatigability during various trunk extension tests has been widely investigated by electromyography (EMG), and its task-dependency is established recently. Hip extensor muscle fatigability during the Sorensen test has been reported. The aim of the present experiments was to evaluate the task-dependency of back and hip extensor muscle fatigue during two variants of the Sorensen test. We hypothesized that the rate of muscular fatigue of the hip and back extensor muscles varies according to the test position. Twenty healthy young males with no history of low back pain volunteered to participate in this cross-sectional study. They were asked to perform two body weight-dependent isometric back extension tests (S1 = Sorensen test; S2 = modified Sorensen on a 45° Roman chair). Surface EMG activity of the paraspinal muscles (T10 and L5 levels) and hip extensor muscles (gluteus maximus; biceps femoris) was recorded, and muscular fatigue was assessed through power spectral analysis of the EMG data by calculating the rate of median power frequency change. We observed hip extensor muscle fatigue simultaneously with paraspinal muscle fatigue during both Sorensen variants. However, only L5 level EMG fatigue indices showed a task-dependency effect between S1 and S2. Hip extensor muscles appear to contribute to load sharing of the upper body mass during both Sorensen variants, but to a different extent because L5 level fatigue differs between the Sorensen variants. Our findings suggest that task-dependency has to be considered when EMG variables are compared between two types of lumbar muscle-fatiguing tasks.
Erector spinae; Hip extensors; Sorensen test; Muscle fatigability; Task-dependency
The purpose of this study was to systematically review the available evidence on lumbar paraspinal compartment syndrome with specific reference to patient demographics, aetiology, types, diagnosis, clinical features, and treatment. This was an Institutional Review Board-exempt study performed at a Level 1 trauma center. A PubMed search was conducted with the title query: lumbar paraspinal compartment syndrome. Eleven articles met our search criteria. Three of the patients with acute paraspinal compartmental syndrome treated with fasciotomy had a full recovery and were able to resume skiing after four months. The aetiology of the onset of lumbar paraspinal compartment syndrome is broadly divided into acute and chronic. Lumbar paraspinal compartment syndrome is one of the causes of back pain with diagnostic clinical features which should be considered in the differential diagnosis of a patient with low back pain. Prospective multicentre trials may provide the surgeon with more insight into the diagnosis and management of lumbar paraspinal compartment syndrome.
This study examined a set of patients who were symptomatic for low back pain and who had significant lumbar hypolordosis as assessed by visual evaluation of magnetic resonance images to investigate the frequency of comorbid paraspinal muscle spasms as determined via history or physical examination.
A retrospective chart review was performed on 50 patients who had significant hypolordosis on magnetic resonance imaging (MRI) (Cobb angle <20°) to determine whether they were positive for paraspinal muscle spasms by either history or physical examination.
Of the 50 patients with significant hypolordosis on MRI, 66% (33) had a history of paraspinal muscle spasms, 76% (38) had a positive physical examination for palpation of paraspinal muscle spasms, and 48% (24) were positive for both history and physical examination.
This retrospective study suggests that most symptomatic patients with significant hypolordosis on lumbar MRI have a positive history or physical examination for paraspinal muscle spasm. Thus, MRI finding of significant hypolordosis (Cobb angle <20°) could potentially be a valuable tool in addition to medical history and physical examination in aiding clinicians in diagnosing paraspinal muscle spasms in symptomatic patients and in helping them to formulate appropriate and effective treatments.
Lordosis; Spinal curvatures; Spinal diseases; Magnetic resonance imaging; Spasm
To describe neurophysiological changes over time in persons with and without spinal complaints, and to assess whether paraspinal denervation predicts change in stenosis on MRI and clinical course.
Prospective, controlled, masked trial.
University spine program.
Persons aged 55–80, screened for polyneuropathy and determined on clinical examination to have spinal stenosis, mechanical low back pain, or no spinal symptoms.
Subjects underwent comprehensive codified history and physical examination, ambulation testing, masked electrodiagnostic testing including paraspinal mapping, and MRI; repeated at >18 months. This publication presents detailed technical information and additional analyses not reported previously.
Main Outcome Measurements
Change in electrodiagnostic findings. Among persons with clinical stenosis, relationship of change in paraspinal mapping scores to MRI findings and clinical changes.
Of 149 initial subjects, 83 (79.3% of eligible subjects) repeated testing at 20 +/− 2 s.d.) months. No significant change in limb muscle spontaneous activity or motor unit pathology was noted in any group. In 23 persons with initial diagnosis of stenosis, paraspinal mapping EMG related to change in diagnosis over time (ANOVA F=3.77, p=0.037), but not to most initial MRI measurements or to change in spinal canal diameter.
Clinical spinal stenosis is neurophysiologically stable in most persons. Paraspinal EMG changes reflect large changes in clinical course, but neither neurophysiological nor clinical changes relate to change in spinal geometry over 20 months.
Spinal Stenosis; Back pain; Electrodiagnosis; Erector spinae; Disk Degeneration; Radiculopathy; Magnetic Resonance Imaging
To investigate the prognostic value of cross-sectional areas (CSA) of paraspinal (multifidus and erector spinae) and psoas muscles on magnetic resonance imaging (MRI) in chronicity of low back pain.
Thirty-eight subjects who visited our hospital for acute low back pain were enrolled. Review of their medical records and telephone interviews were done. Subjects were divided into two groups; chronic back pain group (CBP) and a group showing improvement within 6 months after onset of pain (IBP). The CSA of paraspinal and psoas muscles were obtained at the level of the lower margin of L3 and L5 vertebrae using MRI.
CSA of erector spinae muscle and the proportion of the area to lumbar muscles (paraspinal and psoas muscles) at L5 level in the CBP group were significantly smaller than that of the IBP group (p<0.05). The mean value of CSA of multifidus muscle at L5 level in the CBP group was smaller than that of the IBP group, but was not statistically significant (p>0.05). CSA of psoas muscle at L5 level and all values measured at L3 level were not significantly different between the groups (p>0.05).
CSA of erector spinae muscle at the lower lumbar level and the proportion of the area to the lumbar muscles at the L5 level can be considered to be prognostic factors of chronicity of low back pain.
Low back pain; Magnetic resonance imaging; Cross-sectional area; Muscles
Low back pain (LBP) is one of the most frequent musculoskeletal conditions in industrialized countries and its economic impact is important. Spinal manipulation therapy (SMT) is believed to be a valid approach in the treatment of both acute and chronic LBP. It has also been shown that SMT can modulate the electromyographic (EMG) activity of the paraspinal muscle. The purpose of this study was to investigate, in a group of patients with low back pain, the persistence of changes observed in trunk neuromuscular responses after a spinal manipulation (SMT).
Sixty adult participants with LBP performed a block of 5 flexion-extension movements. Participants in the experimental group (n=30) received lumbar SMT whereas participants in the control group (n=30) were positioned similarly for the treatment but did not receive SMT. Blocks of flexion-extension movements were repeated immediately after the manipulation as well as 5 and 30 minutes after SMT (or control position). EMG activity of paraspinal muscles was recorded at L2 and L5 level and kinematic data were collected to evaluate the lumbo-pelvic kinematics. Pain intensity was noted after each block. Normalized EMG, pain intensity and lumbo-pelvic kinematics were compared across experimental conditions.
Participants from the control group showed a significant increase in EMG activity during the last block (30 min) of flexion-extension trials in both flexion and full-flexion phases at L2. Increase in VAS scores was also observed in the last 2 blocks (5 min and 30 min) in the control group. No significant group x time interaction was seen at L5. No significant difference was observed in the lumbo-pelvic kinematics.
Changes in trunk neuromuscular control following HVLA spinal manipulation may reduce sensitization or muscle fatigue effects related to repetitive movement. Future studies should investigate short term changes in neuromuscular components, tissue properties and clinical outcomes.
Spinal manipulation; Electromyography; Kinematics; Flexion-relaxation phenomenon
Both the paraspinal muscle sparing approach and percutaneous screw fixation are less traumatic procedures in comparison with the conventional midline approach. These techniques have been used with the goal of reducing muscle injury. The purpose of this study was to evaluate and to compare the safety and efficacy of the paraspinal muscle sparing technique and percutaneous screw fixation for the treatment of L5-S1 spondylolisthesis.
Twenty patients who had undergone posterior lumbar interbody fusion (PLIF) at the L5-S1 segment for spondylolisthesis were prospectively studied. They were divided into two groups by screw fixation technique (Group I : paraspinal muscle sparing approach and Group II: percutaneous screw fixation). Clinical outcomes were assessed by Low Back Outcome Score (LBOS) and Visual Analogue Scale (VAS) for back and leg pain at different times after surgery. In addition, modified MacNab's grading criteria were used to assess subjective patients' outcomes 6 months after surgery. Postoperative midline surgical scarring, intraoperative blood loss, mean operation time, and procedure-related complications were analyzed.
Excellent or good results were observed in all patients in both groups 6 months after surgery. Patients in both groups showed marked improvement in terms of LBOSs all over time intervals. Postoperative midline surgical scarring and intraoperative blood loss were lower in Group II compared to Group I although these differences were not statistically significant. Low back pain (LBP) and leg pain in both groups also showed significant improvement when compared to preoperative scores. However, at 7 days and 1 month after surgery, patients in Group II had significantly better LBP scores compared to Group I.
In terms of LBP during the early postoperative period, patients who underwent percutaneous screw fixation showed better results compared to ones who underwent screw fixation via the paraspinal muscle sparing approach. Our results indicate that the percutaneous screw fixation procedure is the preferable minimally invasive technique for reducing LBP associated with L5-S1 spondylolisthesis.
Spondylolisthesis; Paraspinal muscle sparing approach; Percutaneous screw fixation; Back pain
The purpose of this study was to investigate the use of magnetic resonance (MR) imaging and image processing software to determine the functional cross-sectional area (FCSA) (the area of muscle isolated from fat) of the lumbar paraspinal muscles. The measurement of the morphology of the lumbar paraspinal muscles has become the focus of several recent investigations into the aetiology of low back pain. However, the reliability and validity of determining the FCSA of the lumbar paraspinal muscles using MR imaging are yet to be reported. T2 axial MR scans at the L1-S1 spinal levels of six subjects were obtained using identical MR systems and scanning parameters. Lean paraspinal muscle, vertebral body bone and intermuscular fat were manually segmented using image analysis software to assign a grey scale range to the MR signal intensity emitted by each tissue type. The resultant grey scale range for muscle was used to determine FCSA measurements for each of the paraspinal muscles, psoas, quadratus lumborum, erector spinae and lumbar multifidus on each scan slice. As various biological, instrument and measurement factors can affect MR signal intensity, a sensitivity analysis was conducted to determine the error associated in calculating FCSA for paraspinal muscle using a discrete grey scale range. Cross-sectional area and FCSA measurements were repeated three times and reliability indices for the FCSA measurements were obtained, showing excellent reliability, intra class correlation coefficient (mean=0.97, range 0.90–0.99) and %SEM (mean=2.6%, range 0.7–4.8%). In addition, the error associated with miscalculation of the grey scale range for the MR signal intensity of muscle was calculated and found to be low with an error of 20 grey scale units at the upper end of the muscle’s grey scale range resulting in a very small error in the measured muscle FCSA. The method presented in this paper has a variety of practical applications in areas such as evidence-based rehabilitation, biomechanical modelling and the determination of segmental inertial parameters.
Lumbar spine; Magnetic resonance imaging; Cross sectional area; Low back pain; Muscle morphology
In neutral spinal postures with low loading moments the lumbar spine is not inherently stable. Small compromises in paraspinal muscle activity may affect lumbar spinal biomechanics. Proprioceptive feedback from muscle spindles is considered important for control of muscle activity. Because skeletal muscle and muscle spindles are thixotropic, their length history changes their physical properties. The present study explores a mechanism that can affect the responsiveness of paraspinal muscle spindles in the lumbar spine.
This study had two aims: to extend our previous findings demonstrating the history dependent effects of vertebral position on the responsiveness of lumbar paraspinal muscle spindles; and to determine the time course for these effects. Based upon previous studies, if a crossbridge mechanism underlies these thixotropic effects, then the relationship between the magnitude of spindle discharge and the duration of the vertebral position will be one of exponential decay or growth.
A neurophysiological study using the lumbar spine of a feline model.
The discharge from individual muscle spindles afferents innervating lumbar paraspinal muscles in response to the duration and direction of vertebral position were obtained from teased filaments in the L6 dorsal roots of 30 Nembutal-anesthetized cats. The L6 vertebra was controlled using a displacement-controlled feedback motor and was held in each of 3 different conditioning positions for durations of 0, 0.5, 1, 1.5, and 2 seconds. Two of the conditioning positions stretched or shortened the lumbar muscles relative to an intermediate conditioning position. Conditioning positions for all cats ranged from 0.9 – 2.0 mm dorsal and ventralward relative to the intermediate position. These magnitudes were determined based upon the displacement that loaded the L6 vertebra to 50–60% of the cat’s body weight. Conditioning was thought to simulate a motion segment’s position that might be passively maintained due to fixation, external load, a prolonged posture, or structural change. Following conditioning positions that stretched (hold-long) and shortened (hold-short) the spindle, the vertebra was repositioned identically and muscle spindle discharge at rest and to movement was compared with conditioning at the intermediate position.
Lumbar vertebral positions maintained for less than 2 seconds were capable of evoking different discharge rates from lumbar paraspinal muscle spindles despite the vertebra having been returned to identical locations. Both resting spindle discharge and their responsiveness to movement were altered. Conditioning vertebral positions that stretched the spindles decreased spindle activity and positions that unloaded the spindles increased spindle activity upon returning the vertebra to identical original (intermediate) positions. The magnitude of these effects increased as conditioning duration increased to 2 seconds. These effects developed with a time course following a first order exponential reaching a maximal value after approximately 4 seconds of history. The time constant for a hold-short history was 2.6 seconds and for a hold-long history was approximately half of that at 1.1 seconds.
Thixotropic contributions to the responsiveness of muscles spindles in the low back are caused by the rapid, spontaneous formation of stable crossbridges. These sensory alterations due to vertebral history would represent a proprioceptive input not necessarily representative of the current state of intersegmental positioning. As such, they would constitute a source of inaccurate sensory feedback. Examples are presented suggesting ways in which this novel finding may affect spinal physiology.
The objectives of the study were to evaluate the association between lumbar paraspinal muscle density, evaluated on computed tomography (CT) and age, sex and BMI; and to evaluate the association of those changes with low back pain (LBP) and spinal degeneration features in a community-based sample. This study was an ancillary project to the Framingham Study. A sample of 3,529 participants aged 40–80 years had a CT scan performed to assess aortic calcification. 187 individuals were randomly enrolled in this study. LBP in the last 12 months was evaluated using self-report questionnaire. Density (in Hounsfield units) of multifidus and erector spinae was evaluated on CT. The prevalence of intervertebral disc narrowing, facet joint osteoarthritis (FJOA), spondylolysis, spondylolisthesis and spinal stenosis were also evaluated. We used linear regression models to examine the association of paraspinal muscles density with age, sex, BMI, LBP, and spinal degeneration features. The results show that in our study, men have higher density of paraspinal muscles than women, younger individuals have higher density than older ones and individuals with lower weight have higher muscle density than overweight. No differences between individuals with and without LBP were found. Significant association was found between L4 multifidus/erector spinae density and FJOA at L4–L5; between multifidus at L4 and spondylolisthesis at L4–5; and between erector spinae at L4 and L5 with disc narrowing at L4–5 and L5–S1, respectively. We conclude that the paraspinal muscle density decreases with age, and increases BMI. It is associated with at some levels FJOA, spondylolisthesis and disc narrowing at the same level, but not associated with occurrence of LBP.
Low back pain; Paraspinal muscles; Multifidus; Erector spinae; Computed tomography
Fatigue of the gluteus medius (GMed) muscle might be associated with decreases in postural control due to insufficient pelvic stabilization. Men and women might have different muscular recruitment patterns in response to GMed fatigue.
To compare postural control and quality of movement between men and women after a fatiguing hip-abduction exercise.
Descriptive laboratory study.
Patients or Other Participants:
Eighteen men (age = 22 ± 3.64 years, height = 183.37 ± 8.30 cm, mass = 87.02 ±12.53 kg) and 18 women (age = 22 ± 3.14, height = 167.65 ± 5.80 cm, mass = 66.64 ± 10.49 kg) with no history of low back or lower extremity injury participated in our study.
Participants followed a fatiguing protocol that involved a side-lying hip-abduction exercise performed until a 15% shift in electromyographic median frequency of the GMed was reached.
Main Outcome Measure(s):
Baseline and postfatigue measurements of single-leg static balance, dynamic balance, and quality of movement assessed with center-of-pressure measurements, the Star Excursion Balance Test, and lateral step-down test, respectively, were recorded for the dominant lower extremity (as identified by the participant).
We observed no differences in balance deficits between sexes (P > .05); however, we found main effects for time with all of our postfatigue outcome measures (P ≤ .05).
Our findings suggest that postural control and quality of movement were affected negatively after a GMed-fatiguing exercise. At similar levels of local muscle fatigue, men and women had similar measurements of postural control.
gluteus medius muscle; postural control; balance
This study aims to investigate the electrical properties of lumbar paraspinal muscles (LPM) of patients with acute lower back pain (LBP) and to study a new approach, namely Electrical Impedance Myography (EIM), for reliable, low-cost, non-invasive, and real-time assessment of muscle-strained acute LBP.
Patients with muscle-strained acute LBP (n = 30) are compared to a healthy reference group (n = 30). Electrical properties of LPM are studied.
EIM is a novel technique under development for the assessment of neuromuscular disease. Therefore, it is speculated that EIM can be employed for the assessment of muscle-strained acute LBP.
Surface electrodes, in 2-electrode configurations, was used to measure the electrical properties of patient's and healthy subject's LPM at six different frequencies (0.02, 25.02, 50.02, 1000.02, 3000.02, and 5000.02 kHz), with the amplitude of the applied voltage limited to 200 mV. Parameters of impedance (Z), extracellular resistance (Re), intracellular resistance (Ri), and the ratio of extracellular resistance to intracellular resistance (Re/Ri) of LBP patient's and healthy subject's LPM were assessed to see if significant difference in values obtained in muscle-strained acute LBP patients existed.
Intraclass correlation coefficient (ICC) showed that all measurements (ICC>0.96 for all studying parameters: Z, Re, Ri, and Re/Ri) had good reliability and validity. Significant differences were found on Z between LBP patient's and healthy subject's LPM at all studying frequencies, with p<0.05 for all frequencies. It was also found that Re (p<0.05) and Re/Ri (p<0.05) of LBP patient's LPM was significant smaller than that of healthy subjects while Ri (p<0.05) of LBP patient's LPM was significant greater than that of healthy subjects. No statistical significant difference was found between the left and right LPM of LBP patients and healthy subjects on the four studying parameters.
EIM is a promising technique for assessing muscle-strained acute LBP.
We investigated back muscle fatigue and endurance in patients with lumbar disc herniation before and after surgery, and established the degree of association between perceived fatigue and objectively measured fatigue. Additionally, the relationships between muscle fatigue and endurance time on the one hand, and activity, participation, self-efficacy and health on the other, were investigated to clarify the grades of association between these factors. Forty-three consecutive patients with lumbar disc herniation were tested before surgery and 4 weeks after surgery. The protocol comprised an isometric endurance test (modified Sørensen’s test) with concomitant measures of electromyography, and Borg ratings of pain and fatigue. To measure activity, participation, self-efficacy and health, the patients also filled in questionnaires. Results showed a post-operatively significant improvement in lumbar muscle fatigue expressed as a flatter L5 slope for the men. No significant improvement was found for endurance times or for Borg ratings. Endurance time correlated with questionnaire answers on physical activity, the Roland–Morris, the Oswestry, self-efficacy and some items of the SF-36 with correlation coefficients ranging from 0.52 to 0.91. The L5 slope correlated with the Roland–Morris, the Oswestry and some items of the SF-36 only in women with correlation coefficients between 0.53 and 0.77. We conclude that the effects of surgery reduced muscle fatigue for the men. There is an association between muscle fatigue and endurance with activity limitations, participation restrictions, self-efficacy and health in patients undergoing surgery for lumbar disc herniation.
Electromyography; Endurance; Lumbar disc herniation; Muscle fatigue; Subjective factors
Retroperitoneal hemorrhage is a life-threatening condition. This is the first reported case of rupture of one of multiple thoraco-lumbar artery aneurysms associated with a metameric paraspinal vascular lesion.
A 77-year-old female patient presented to the emergency room with a new onset of left-sided low back pain shooting down the leg associated with weakness, numbness, and inability to walk. On physical examination, there was a notable left paraspinal swelling with a harsh bruit audible in the same area, left flank ecchymosis and a positive straight leg raising test. A computed tomography (CT) scan showed a large retroperitoneal hematoma. Digital subtraction angiography showed a large left paraspinal high-flow arteriovenous lesion, with large arterial aneurysms of the left T11, T12, and L1 segmental arteries. The patient was successfully treated with endovascular aneurysm embolization using coils and Onyx-34. Six months following the procedure, the patient had fully recovered, and a follow-up angiogram showed no residual or recurrent aneurysms.
Thoraco-lumbar artery aneurysms have never previously been described in association with a metameric paraspinal vascular malformation. We report a case of retroperitoneal hemorrhage due to rupture of one of several high-flow artery aneurysms of a paraspinal arteriovenous malformation (AVM). The diagnosis was made on CTA, MRI, and angiography, and the lesion was successfully treated by transarterial embolization.
Arteriovenous malformation; endovascular embolization; metameric lesion; Onyx-34
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.
Key words Chronic low back pain; Erector spinae muscle; MRI; Muscle biopsy; Fibre type; distribution
Studies employing modified Biering-Sørenson tests have reported that low back endurance is related to the potential for developing low back pain. Understanding the manner in which spinal musculature fatigues in people with and without LBP is necessary to gain insight into the sensitivity of the modified Biering-Sørenson test to differentiate back health. Twenty male volunteers were divided into a LBP group of subjects with current subacute or a history of LBP that limited their activity (n = 10) and a control group (n = 10). The median frequency of the fast Fourier transform was calculated from bilateral surface electromyography (EMG) of the upper lumbar erector spinae (ULES), lower lumbar erector spinae (LLES) and biceps femoris while maintaining a prescribed modified Biering-Sørensen test position and exerting isometric forces equivalent to 100, 120, 140 and 160% of the estimated mass of the head-arms-trunk (HAT) segment. Time to failure was also investigated across the percentages of HAT. Fatigue time decreased with increasing load and differences between groups increased as load increased, however these differences were not significant. Significant differences in the EMG median frequency between groups occurred in the right biceps femoris (p ≤ 0.05) with significant pairwise differences occurring at 140% for the left biceps femoris and at 160% for the right biceps femoris. There were significant pairwise differences at 120% for average EMG of the right biceps femoris and at 140% for the right ULES, and right and left biceps femoris (p ≤ 0.05). The modified Biering-Sørensen test as usually performed at 100% HAT is not sufficient to demonstrate significant differences between controls and subjects with varying degrees of mild back disability based on the Oswestry classification.
The results do not wholly support the modified Biering-Sørensen test utilizing resistance of 100% HAT to discern differences in fatigue in subjects with mild low back pain.
A greater activation of the biceps femoris by low back pain individuals probably contributed to the lack of significant differences in back fatigue times.
The possibility exists that subjects with more sophisticated strategies could yield higher fatigue times despite inferior neuromuscular fatigue and the existence of low back pain.
Endurance; electromyography; median frequency; back muscles; healthy subjects
Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is responsible for a broad range of infections. We report the case of a 46-year-old gentleman with a history of untreated, uncomplicated Hepatitis C who presented with a 2-month history of back pain and was found to have abscesses in his psoas and right paraspinal muscles with subsequent lumbar spine osteomyelitis. Despite drainage and appropriate antibiotic management the patient's clinical condition deteriorated and he developed new upper extremity weakness and sensory deficits on physical exam. Repeat imaging showed new, severe compression of the spinal cord and cauda equina from C1 to the sacrum by a spinal epidural abscess. After surgical intervention and continued medical therapy, the patient recovered completely. This case illustrates a case of CA-MRSA pyomyositis that progressed to lumbar osteomyelitis and a spinal epidural abscess extending the entire length of the spinal canal.
Facet joint injection is considered to be a safe procedure. There have been some reported cases of facet joint pyogenic infection and also 3 cases of facet joint infection spreading to paraspinal muscle and epidural space due to intra-articular injections. To the author's knowledge, paraspinal and epidural abscesses after facet joint injection without facet joint pyogenic infection have not been reported. Here we report a case in which extra-articular facet joint injection resulted in paraspinal and epidural abscesses without facet joint infection. A 50-year-old man presenting with acute back pain and fever was admitted to the hospital. He had the history of diabetes mellitus and had undergone the extra-articular facet joint injection due to a facet joint syndrome diagnosis at a private clinic 5 days earlier. Physical examination showed tenderness over the paraspinal region. Magnetic resonance image (MRI) demonstrated the paraspinal abscess around the fourth and fifth spinous processes with an additional epidural abscess compressing the thecal sac. The facet joints were preserved. The laboratory results showed a white blood cell count of 14.9 × 109 per liter, an erythrocyte sedimentation rate of 52mm/hour, and 10.88mg/dL of C-reactive protein. Laminectomy and drainage were performed. The pus was found in the paraspinal muscles, which was communicated with the epidural space through a hole in the ligamentum flavum. Cultures grew Staphylococcus aureus. Paraspinal abscess communicated with epidural abscess is a rare complication of extra-articular facet joint injection demonstrating an abscess formation after an invasive procedure near the spine is highly possible.
Complication; infection; injection; facet joint
To report a case of cervical instability from an os odontoideum that presented as posterior thoracic pain and to present a review of the literature.
Thoracic posterior paraspinal spasms and pain are common chief complaints in individuals with spinal abnormalities.
A 19-year-old man presented with posterior thoracic pain for nearly 1 year following a college sports-related injury (lacrosse). Computed tomography and magnetic resonance imaging did not reveal any significant thoracic or lumbar spinal cord or nerve root pathology, but did reveal an incidental finding of an os odontoideum.
Surgical stabilization of the atlantoaxial instability resulting from the os odontoideum resulted in complete resolution of the patient's thoracic pain.
Thoracic back pain without a clear thoracic spine etiology warrants further workup to rule out the possibility of spinal instability.
Atlantoaxial instability; Os odontoideum; Surgery; Spinal; Pain; Thoracic; Injuries; Sports
Context: Muscular fatigue impedes sensorimotor function and may increase the risk of shoulder injury during activity. The effects of fatigue on the sensorimotor system of the shoulder have been studied with various results. Deceleration times have been used to study neuromuscular control of the shoulder; however, no studies involving the effects of fatigue on deceleration times have been reported.
Objective: To compare shoulder deceleration times after a shoulder internal rotation perturbation before and after a repetitive throwing exercise protocol.
Design: A 2 × 2 repeated-measures design.
Setting: Exercise and sport injury laboratory.
Patients or Other Participants: Twenty healthy, recreationally active men (age = 24.76 ± 4.03 years, height = 178.41 ± 8.36 cm, mass = 80.16 ± 15.20 kg) volunteered to participate in the study. To ensure familiarity with the overhead motion, all subjects chosen had previously participated in an overhead throwing sport.
Intervention(s): The independent variables were time (preintervention and postintervention) and session (experimental and control). The intervention consisted of continuous overhead throwing. The subjects were considered fatigued when a 10% decrease in velocity was noted on 3 consecutive pitches.
Main Outcome Measure(s): Time necessary to decelerate from an internal rotation perturbation.
Results: Deceleration time was significantly increased by the fatiguing intervention (
P = .001).
Conclusions: The decreased ability to decelerate may be an adaptive response by the subjects to dissipate a lower percentage of force per second.
shoulder fatigue; shoulder neuromuscular control; throwing fatigue protocol
The ability to accurately estimate quadriceps voluntary activation is an important tool for assessing neuromuscular function after a variety of knee injuries. Different techniques have been used to assess quadriceps volitional activation, including various stimulating electrode types and electrode configurations, yet the optimal electrode types and configurations for depolarizing motor units in the attempt to assess muscle activation are unknown.
To determine whether stimulating electrode type and configuration affect quadriceps central activation ratio (CAR) and percentage-of-activation measurements in healthy participants.
Patients and Other Participants:
Twenty participants (13 men, 7 women; age = 26 ± 5.3 years, height = 173.85 ± 7.3 cm, mass = 77.37 ± 16 kg) volunteered.
All participants performed 4 counter-balanced muscle activation tests incorporating 2 different electrode types (self-adhesive, carbon-impregnated) and 2 electrode configurations (vastus, rectus).
Main Outcome Measure(s):
Quadriceps activation was calculated with the CAR and percentage-of-activation equations, which were derived from superimposed burst and resting torque measurements.
No differences were found between conditions for CAR and percentage-of-activation measurements, whereas resting twitch torque was higher in the rectus configuration for both self-adhesive (216 ± 66.98 Nm) and carbon-impregnated (209.1 ± 68.22 Nm) electrodes than in the vastus configuration (209.5 ± 65.5 Nm and 204 ± 62.7 Nm, respectively) for these electrode types (F1,19 = 4.87, P = .04). In addition, resting twitch torque was greater for both electrode configurations with self-adhesive electrodes than with carbon-impregnated electrodes (F1,19 = 9.33, P = .007). Bland-Altman plots revealed acceptable mean differences for agreement between electrode type and configuration for CAR and percentage of activation, but limits of agreement were wide.
Although these electrode configurations and types might not necessarily be able to be used interchangeably, differences in electrode type and configuration did not seem to affect CAR and percentage-of-activation outcome measures.
burst superimposition; interpolated twitch technique; central activation ratio; knee; motor neurons