Riikka Niemeläinen

Substantial Asymmetry in Paraspinal Muscle Cross-Sectional Area in Healthy Adults Questions Its Value as a Marker of Low Back Pain and Pathology

Study Design. A cross-sectional population-based study of paraspinal muscle asymmetry. Objective. To examine level- and side-to-side differences in paraspinal muscle areas on magnetic resonance images in a population-based sample of middle aged men without low back pain (LBP). Summary of Background Data. Level- and side-specific multifidus muscle atrophy and fat infiltration have been suggested as possible markers for localized spinal pathology and LBP, but prior studies have limited generalizability due to small sample sizes, young age of samples and measurement issues. Methods. From a general population sample of 600 twin men, those reporting no LBP during the prior year, no previous spinal fractures, and no bed rest for at least 1 week in the last 12 months were included in the study. All subjects had T2-weighted axial images available for the three lowest lumbar levels. Both total and fat-free cross-sectional areas (CSAs) of the multifidus and erector spinae muscles at the mid-disc level were measured. Intrarater reliability ranged between 0.90 and 0.98 for area measurements and 0.86 and 0.92 for measurements of side-to-side differences. Data were analyzed using descriptive statistics and paired t tests. Results. Subjects consisted of 126 men whose mean multifidus total CSA measurements varied between 7.3 and 11.1 cm2 and between 6.9 and 10.8 cm2 for right and left sides, respectively, depending on the level. The corresponding mean areas for erector spinae were 9.4 to 19.6 cm2 for right side and 10.4 to 19.7 cm2 for left side. The multifidus was larger on the right side than on the left side in 65% to 68% of subjects, depending on spinal level (P < 0.001). The mean asymmetry at the three lowest lumbar levels was 10% to 13.2% and was smallest at L4-L5. Multifidus side-to-side asymmetry ranged from 0.1% to 44.3%. For erector spinae, the left-side measurements tended to be larger, reaching statistical significance (P < 0.0001) for the two lowest levels. The mean side-to-side asymmetry increased caudally for erector spinae, from 8.2% to 18.8% and was significantly different between adjacent levels (P < 0.01). The amount of intramuscular fat significantly increased caudally for both muscles. Conclusion. Paraspinal muscle asymmetry greater than 10% was commonly found in men without a history of LBP. This suggests caution in using level- and side-specific paraspinal muscle asymmetry to identify subjects with LBP and spinal pathology.

Is level- and side-specific multifidus asymmetry a marker for lumbar disc pathology?

BACKGROUND CONTEXT Several reports suggest that level- and side-specific multifidus atrophy or fat infiltration may be related to localized spinal pathology and symptoms. In particular, a study using a porcine model reported rapid level- and side-specific multifidus atrophy and adipocyte enlargement resulting from anterolateral disc or nerve root lesions. PURPOSE To investigate asymmetry in cross-sectional area (CSA) and fat infiltration in multifidus and other paraspinal muscles in patients with acute or subacute unilateral symptoms of radiculopathy and concordant posterolateral disc herniation. If multifidus asymmetry is indeed related to local pathology, this may serve as a marker for helping to target the search for less clearly identifiable pathology responsible for low back-related symptoms, which currently remains elusive in approximately 85% of those seeking care. STUDY DESIGN Cross-sectional observational study. PATIENT SAMPLE Subjects were patients referred to magnetic resonance imaging (MRI) with unilateral leg symptoms of less than 6 weeks onset suggestive of radiculopathy, with a consistent posterolateral lumbar disc herniation verified on imaging. METHODS Using T2-weighted axial MRI, measurements were obtained for total muscle CSA and signal intensity, functional (fat-free) CSA, and the ratio of functional CSA to total CSA. RESULTS Forty-three subjects met the inclusion criteria. The ratio of functional CSA to total muscle CSA was smaller on the side of the herniation than on the unaffected side, both below (mean 0.69 vs. 0.72, p=.007) and at the level of herniation (mean 0.78 vs. 0.80, p=.031). Multifidus signal intensity (fat infiltration) was greater on the side of the herniation at the level below the herniation (p=.014). Contrary to expectation, greater total multifidus CSA was found ipsilateral to the pathology at the level of herniation (p=.033). No asymmetries were found at the level above the herniation or in any other paraspinal muscles, with the exception of higher signal in the erector spinae at the level and side of herniation. CONCLUSIONS Multifidus may be particularly responsive to, or indicative of, localized lumbar disc or nerve root pathology within the first 6 weeks of symptoms as expressed through fat infiltration, but not through CSA asymmetry on MRI. However, such measurements are not reliable markers of lumbar pathology on an individual basis for use in clinical or research settings.

Prevalence and Characteristics of Upper or Mid-Back Pain in Finnish Men

Study Design. Descriptive epidemiologic study. Objectives. To examine the 1-year prevalence, severity, and frequency of mid-back pain in a general population sample of men, with comparisons to neck and low back pain. Summary of Background Data. No previous studies reporting the characteristics of mid-back pain in a general population were found. Methods. A total of 600 Finnish men 35 to 70 years of age were drawn from a population-based twin sample and interviewed with standardized pain questions. Results. The 1-year prevalence of mid-back pain was 17.0% (95% confidence interval, 14.3–19.7) compared to 64.0% (95% confidence interval, 60.6–67.5) for neck and 66.8% (95% confidence interval, 63.4–70.3) for low back pain. The frequency of pain over the previous year among those with mid- and low back pain was less than for neck pain. The mean severity of the worst pain episode was highest for low back pain followed by mid-back and neck pain, which were similar. Associated disability tended to be less frequent from mid-back pain (23.5% vs. 30.3%–41.1%). Odds ratios for neck and low back pain when mid-back pain was reported were 2.32 and 2.86, respectively. Conclusion. The prevalence of mid-back pain was approximately one fourth that of neck and low back pain and was somewhat less likely to be disabling. In cases of mid-back pain, spinal comorbidity was nearly always reported.

Quantitative measures of modic changes in lumbar spine magnetic resonance imaging: intra- and inter-rater reliability.

Study Design. A measurement reliability study. Objective. To develop quantitative measures for Modic changes (MCs) on magnetic resonance (MR) images and evaluate measurement reliability. Summary of Background Data. MCs have been studied for more than 20 years but the clinical significance remains controversial. Little effort has been made to improve the measurement of MCs. Methods. The study was approved by the responsible institutional review board. On the basis of Modic classification, a series of quantitative dimension and signal intensity measures were developed for assessing MCs. Midsagittal T1- and T2-weighted MR images from 83 lumbar spines were then qualitatively and quantitatively assessed by two observers independently. Kappa and intraclass correlation coefficient (ICC) were used to examine intra- and inter-rater reliability. Pearson correlation coefficient was used to assess the relationships between the quantitative measurements of MCs. Mean absolute deviation (MAD) and Bland-Altman plots also were used to evaluate measurement errors and limits of agreement for selected measures. Results. For Modic classification, intrarater agreement was excellent (&kgr; = 0.88) and inter-rater agreement was substantial (&kgr; = 0.79). Intrarater agreement also was excellent when obtaining dimension measurements (ICC = 0.82–0.96) from T1- or T2-weighted images and inter-rater agreement was slightly greater using T1-weighted images (ICC = 0.73–0.88) than T2-weighted images (ICC = 0.66–0.82). Signal intensity measurements on T2-weighted images were found to have almost perfect intra- and inter-rater reliability (ICC = 0.92–0.99). The correlation analysis demonstrated that the quantitative measures represent different constructs. The MAD and Bland-Altman Plots further confirmed the high reliability of the area ratio, MCs mean signal intensity and MCs total signal intensity measurements. Conclusion. Three quantitative measures are suggested to assess the severity of MCs, which provide reliable, precise measurements for research on the etiology, pathogenesis, and clinical relevance of MCs.

Quantitative measurement of intervertebral disc signal using MRI

AIM To investigate the spinal cord as an alternative intra-body reference to cerebrospinal fluid (CSF) in evaluating thoracic disc signal intensity. MATERIALS AND METHODS T2-weighted magnetic resonance imaging (MRI) images of T6-T12 were obtained using 1.5 T machines for a population-based sample of 523 men aged 35-70 years. Quantitative data on the signal intensities were acquired using an image analysis program (SpEx). A random sample of 30 subjects and intraclass correlation coefficients (ICC) were used to examine the repeatability of the spinal cord measurements. The validity of using the spinal cord as a reference was examined by correlating cord and CSF samples. Finally, thoracic disc signal was validated by correlating it with age without adjustment and adjusting for either cord or CSF. Pearsons r was used for correlational analyses. RESULTS The repeatability of the spinal cord signal measurements was extremely high (>or=0.99). The correlations between the signals of spinal cord and CSF by level were all above 0.9. The spinal cord-adjusted disc signal and age correlated similarly with CSF-adjusted disc signal and age (r=-0.30 to -0.40 versus r=-0.26 to -0.36). CONCLUSION Adjacent spinal cord is a good alternative reference to the current reference standard, CSF, for quantitative measurements of disc signal intensity. Clearly fewer levels were excluded when using spinal cord as compared to CSF due to missing reference samples.

The prevalence and characteristics of thoracic magnetic resonance imaging findings in men.

Study Design. A cross-sectional study of thoracic magnetic resonance image (MRI) findings. Objective. To examine the prevalence of different thoracic MRI findings for T6–T12 and their associations with age and one another by level. Summary of Background Data. There is a dearth of descriptive epidemiology of thoracic MRI findings in the general population. Methods. Thoracic MRIs of 524 men were assessed qualitatively and quantitatively for a variety of findings, including disc bulging, height and signal, vertebral deformities, endplate irregularities, osteophytes, and hemangiomas. Descriptive statistics, correlation coefficients and STATAs survey analysis were used. Results. In the lower thoracic spine, 5.4% to 9.5% of the discs, depending on level, were qualitatively assessed as moderately to severely narrowed. Anterior bulging was more common than posterior, which was relatively rare and mild when present. Signal was lower in the midthoracic than lower discs. At least 1 moderate or severe vertebral deformity was found in 6.1% of the subjects, suggesting fracture, and hemangiomas were identified in 2.3% of subjects. Disc signal correlated most highly with age (r = 0.31–0.42). Qualitatively assessed disc height narrowing (r = 0.29–0.46) and quantitative disc height (r = 0.11–0.29) were associated with disc signal. Upper and lower endplate irregularities were associated with one another (r = 0.17–0.32), as were bulging and osteophytes, anteriorly (r = 0.35–0.61) and posteriorly (r = 0.26–0.45). Conclusion. Degenerative MRI findings beyond a mild grade were not commonly observed in the thoracic spine among 35–70-year-old men. Posterior bulges, in particular, were rare. The highest correlation with age existed for disc signal. Different MRI findings were associated with one another, but the magnitude of association varied by level. The effects of individual judgments and disc level on prevalence rates were apparent.

Lumbar spinal stenosis is a highly genetic condition partly mediated by disc degeneration.

Lumbar spinal stenosis is one of the most commonly diagnosed spinal disorders in older adults. Although the pathophysiology of the clinical syndrome is not well understood, a narrow central canal or intervertebral foramen is an essential or defining feature. The aim of the present study was to estimate the magnitude of genetic versus environmental influences on central lumbar spinal stenosis and to investigate disc degeneration and stature or bone development as possible genetic pathways.

Are Performance-Based Functional Assessments Superior to Semistructured Interviews for Enhancing Return-to-Work Outcomes?

OBJECTIVE To examine whether use of functional capacity evaluation (FCE) leads to better outcomes for injured workers. DESIGN Cluster randomized controlled trial conducted with analysis at level of claimant. SETTING Rehabilitation facility. PARTICIPANTS Participants included claimants (N=203); of these, 103 were tested with FCE. Data were collected on all claimants undergoing RTW assessment at the facility for musculoskeletal conditions. Participants were predominantly employed (59%) men (73%) with chronic musculoskeletal conditions (median duration, 496d). INTERVENTIONS FCEs are commonly used to identify work abilities and inform return-to-work (RTW) decisions. Therefore, FCE results have important consequences. Clinicians who were trained and experienced in performing FCEs were randomized into 2 groups. One group included 14 clinicians who were trained to conduct a semistructured functional interview; the other group (control group) continued to use standard FCE procedures. MAIN OUTCOME MEASURES Outcomes included RTW recommendations after assessment, functional work level at time of assessment and 1, 3, and 6 months after assessment, and compensation outcomes. Analysis included Mann-Whitney U, chi-square, and t tests. RESULTS All outcomes were similar between groups, and no statistically or clinically significant differences were observed. Mean differences between groups on functional work levels at assessment and follow-up ranged from 0.1 to 0.3 out of 4 (3%-8% difference, P>.05). CONCLUSIONS Performance-based FCEs did not appear to enhance RTW outcomes beyond information gained from semistructured functional interviewing. Use of functional interviewing has the potential to improve efficiency of RTW assessment without compromising clinical, RTW, or compensation outcomes.

Brief Report: Lumbar Spinal Stenosis Is a Highly Genetic Condition Partly Mediated by Disc Degeneration

Lumbar spinal stenosis is one of the most commonly diagnosed spinal disorders in older adults. Although the pathophysiology of the clinical syndrome is not well understood, a narrow central canal or intervertebral foramen is an essential or defining feature. The aim of the present study was to estimate the magnitude of genetic versus environmental influences on central lumbar spinal stenosis and to investigate disc degeneration and stature or bone development as possible genetic pathways.

Reference Values for the SF-36 in Canadian Injured Workers Undergoing Rehabilitation

Purpose The Medical Outcomes Study 36-item Short Form Survey (SF-36) is a widely used measure of health-related quality of life and normative reference values have been published for the general population of several countries. Since injured workers often experience pain, disability and other health challenges, we evaluated SF-36 reference values for Canadian workers’ compensation claimants undergoing rehabilitation. Methods Descriptive cross-sectional design. Data were gathered as part of a study aimed at developing a tool for selecting rehabilitation programs. Data were available on a wide variety of measures, including the SF-36. We calculated age- and sex-adjusted reference values, and stratified analyses based on type of rehabilitation, employment status and diagnostic group. Results Data were available on 5,622 claimants undergoing rehabilitation. Claimants reported significant limitations on all SF-36 scales, but were especially limited on the Role Emotional and Bodily Pain scales (~3 standard deviations below typical Canadian norms). Unemployed, middle-aged claimants undergoing chronic pain programs reported the lowest health status, but SF-36 scores varied minimally across diagnoses. Conclusions Claimant scores on the SF-36 were below population norms across all health scales and differed depending on age, employment status and type of rehabilitation. These data will be useful for assessing the health status of injured workers and evaluating the effect of rehabilitation interventions.