Magnetic resonance imaging study of cross-sectional area of the cervical extensor musculature in an asymptomatic cohort

Changes in cross-sectional areas of posterior extensor muscles in thoracic spine: a 10-year longitudinal MRI study

Age-related changes in the posterior extensor muscles of the cervical and lumbar spine have been reported in some studies; however, longitudinal changes in the thoracic spine of healthy subjects are rarely reported. Therefore, this study aimed to evaluate changes in the cross-sectional areas (CSAs) of posterior extensor muscles in the thoracic spine over 10 years and identify related factors. The subjects of this study were 85 volunteers (mean age: 44.7 ± 11.5) and the average follow-up period was about 10 years. The CSAs of the transversospinalis muscles, erector spinae muscles, and total CSAs of the extensor muscles from T1/2 to T11/12 were measured on magnetic resonance imaging. The extent of muscle fat infiltration was assessed by the signal intensity (luminance) of the extensor muscles' total cross-section compared to a section of pure muscle. We applied a Poisson regression model, which is included in the generalized linear model, and first examined the univariate (crude) association between each relevant factor (age, sex, body mass index, lifestyle, back pain, neck pain, neck stiffness, and intervertebral disc degeneration) and CSA changes. Then, we constructed a multivariate model, which included age, sex, and related factors in the univariate analysis. The mean CSAs of the transversospinalis muscles, erector spinae muscles, and total CSAs of the extensor muscles significantly increased over 10 years. Exercise habit was associated with increased CSAs of the erector spinae muscles and the total area of the extensor muscles. The cross-section mean luminance significantly increased from baseline, indicating a significant increase of fat infiltration in the posterior extensor muscles. Progression of disc degeneration was inversely associated with increased fat infiltration in the total extensor muscles.

Cervical Flexor–Extensor Muscle Disparity in Monomelic Amyotrophy (Hirayama Disease): Evidence from a Comprehensive Morphometric Evaluation of Subaxial Paraspinal Musculature

Background  Monomelic amyotrophy (Hirayama disease) has been established to have accompanied biomechanical abnormalities such as flexion hypermobility and sagittal imbalance. Paraspinal muscles, the major contributor to cervical biomechanics, have, however, not been comprehensively evaluated in the disease. The objective of this study was to compare the morphology of the subaxial cervical paraspinal musculature in patients with and without Hirayama disease.

Materials and Methods  A retrospective case-control study of 64 patients with Hirayama disease and 64 age- and sex-matched controls was performed . Cross-sectional areas (CSAs) of the superficial and deep flexors and extensors from C3 to C7 were measured on T2-weighted magnetic resonance imaging sequences. Student's t -test was used to compare differences between the paraspinal muscle CSAs in the study and control groups.

Results  Compared with controls, patients with Hirayama disease were found to have larger flexors and smaller extensors at all levels. The overall subaxial muscle area values for superficial flexors and deep flexors were significantly larger ( p  < 0.0001) in patients, while the corresponding superficial extensor and deep extensor area values were significantly smaller than in controls ( p  = 0.01 and < 0.0001, respectively). The patient group demonstrated stronger subaxial deep flexor–deep extensor, superficial flexor–superficial extensor, and total flexor–total extensor ratios ( p  < 0.0001).

Conclusion  Patients with Hirayama disease have morphometric alterations at all levels of their subaxial cervical paraspinal musculature. These patients have abnormally large flexors and small extensors compared with controls. This flexor–extensor muscle disparity could be utilized as a potentially modifiable factor in the management of the disease.

Association between muscle morphology changes, cervical spine degeneration and clinical features in patients with chronic nonspecific neck pain: a magnetic resonance imaging analysis

PURPOSE

The primary objective of the present study was to investigate the correlations among cervical paraspinal muscle morphology changes (fatty infiltration (FI) and muscle atrophy), cervical degeneration and clinical features in patients with chronic nonspecific neck pain (CNSNP).

METHODS

The magnetic resonance imaging (MRI) data of 55 consecutive patients (average age 35.80) with CNSNP were analyzed in this cross-sectional study. Muscle morphology changes in seven groups of paraspinal muscles, indicated by the adjusted cross-sectional area (aCSA) and FI ratio (FI%), were measured from C3/4 to C6/7. The correlations of these changes with disc degeneration, cervical balance (C2-7 angle and cervical alignment) and clinical features (severity of neck pain and related disability and the frequency of acute neck pain (ANP) recurrence) were evaluated.

RESULTS

Significant correlations between FI% and aCSA and the grade of disc degeneration were observed in specific muscle groups at each level (p<0.05). Morphological changes in the deep extensors and superficial paraspinal muscles were significantly associated with cervical balance parameters (p<0.05). The FI% showed a significant positive correlation, while aCSA showed a significant negative correlation with the severity of neck pain and related disability (p<0.05). Correlations between morphological changes and the frequency of ANP recurrence were also present for some muscles (p<0.05).

CONCLUSION

Correlations among muscle morphology changes, cervical degeneration and clinical features were established for patients with CNSNP, and muscle volume changes and FI might affect CNSNP in diverse manners through different paraspinal muscle groups. These results implicated the complex contribution of muscle morphological changes to cervical degeneration and the clinical course of CNSNP.

Sex and posture dependence of neck muscle size-strength relationships

Neck muscle size and strength have been linked to lower injury risk and reduced pain. However, prior findings have been inconclusive and have failed to clarify whether there are sex differences in neck muscle size-strength relationships. Such differences may point to an underlying cause for the reported sex difference in neck pain prevalence. Thirty participants (13 males, 17 females) who underwent neck strength testing and MR imaging were analyzed. Strength was measured in three conditions that differed in posture and exertion direction. Muscle size was quantified by three metrics: anatomical cross-sectional area (ACSA), muscle volume (MV), and an estimate of physiological cross-sectional area-reconstruction-based cross-sectional area (RCSA). Inter-posture strength correlations, muscle size-strength correlations, and sex differences were analyzed with linear regression. Males were approximately 65% stronger and had significantly larger muscles. Strength varied significantly across postures, but only female strength values for different postures were significantly correlated. Observed in males only, the sternocleidomastoid (SCM) was a strong predictor of flexion strength in the neutral posture while the anterior scalene (AS) was more involved in the extended. No extensor's size was significantly linked to extension strength. A greater amount of force variation is unexplained by muscle size alone in females than in males. Males and females exhibited distinct size-strength relationships, highlighting the need for sex-specific models and analyses and the greater potential effect of non-morphometric factors on force generating capacity in females. No advantage of one muscle size metric over another in strength prediction was evidenced.

Reliability and Validity of Panoramic Ultrasound Imaging for Evaluating Muscular Quality and Morphology: A Systematic Review

Panoramic ultrasound (US) is a novel method used to assess linear dimensions, cross-sectional area, fatty infiltrate and echo-intensity features of muscles that cannot be measured with B-mode US. However, a structured overview of its validity and reliability is lacking. MEDLINE, PubMed, SCOPUS and Web of Science databases were systematically searched for studies evaluating reliability or validity data on panoramic US imaging to determine the muscular morphology and/or quality of skeletal muscles. Most studies had acceptable methodological quality. Seventeen studies analyzing reliability (n = 16) or validity (n = 5) were included. Twelve studies assessed cross-sectional area, seven studies assessed echo-intensity, five assessed linear dimensions (fascicle/tendon length, muscle/subcutaneous adipose thickness or between-structure distance) and one assessed intramuscular fat. Panoramic US seems to be a reliable and valid tool for the assessment of muscle morphology and quality in healthy populations at specific locations, particularly the lower extremities. Studies including scanning procedures are needed to confirm these findings in locations not included in this revision and in both clinical and healthy populations.

Cross-sectional area of the cervical extensors assessed with panoramic ultrasound imaging: Preliminary data in healthy people

BACKGROUND

Studies analyzing morphometry of neck extensor musculature have mostly used Magnetic Resonance Imaging (MRI). Panoramic Ultrasound View could be used for obtaining high-quality 2D cross-sectional images with a wide field of view more cost-effectively imaging acquisition by creating an automatic construction of 2D cross-sectional images.

OBJECTIVE

To measure neck extensors cross-sectional area (CSA) using panoramic ultrasound view in healthy subjects.

DESIGN

Cross-sectional study.

METHODS

Panoramic B-mode ultrasound images of the neck extensor muscles at C4/C5 level were acquired in 25 healthy subjects (40% women, mean age: 24 ± 5 years) by an experienced assessor. The CSA of the upper trapezius, splenius (layer), semispinalis (layer), multifidi, short rotators, and levator scapulae were calculated. The relative percentage in the total neck extensor muscle volume of each CSA was also determined. Sex and side-to-side comparisons were conducted.

RESULTS

Men showed larger CSAs than women in all muscles (all, P < 0.01). No side-to-side differences were found in either men or women (all, P > 0.05). Significant positive associations between CSA with weight (r: 0.654 to 0.375, P < 0.01), height (r: 0.386 to 0.581, P < 0.05), and BMI (r: 0.369 to 0.563, P < 0.05) were found. Men showed greater percentage of upper trapezius and semispinalis muscle layers than women (P < 0.01), whereas women had a greater percentage of levator scapulae muscle than men (P < 0.01) from the total volume of the neck extensors. No side-to-side differences were found either.

CONCLUSIONS

The current study describes CSA, as assessed with panoramic ultrasound view, of the neck extensors in healthy people. Men exhibited greater CSA than women with no side-to-side differences.

Is there cervical spine muscle weakness in patients with Hirayama disease? A morphological study about cross-sectional areas of muscles on MRI

PURPOSE

Patients with Hirayama disease (HD) present with a larger range of neck flexion and show signs of cervical spine instability. Cervical spine stability largely relies on cervical spine muscles. The purpose of this study was to compare the cross-sectional areas (CSAs) of cervical spine muscles between patients with HD and healthy controls, providing some insights into whether there is cervical spine muscle weakness and incongruence in HD patients.

METHODS

In this retrospective study, cervical spine muscles CSAs of 44 HD patients, as well as that of 44 age- and sex-matched healthy counterparts, were measured on the T2-weighted axial MR images. The ratios of cervical spine muscles CSA to the corresponding vertebral body areas, defined as R-CSAs, and the flexor/extensor CSA ratios were computed and compared between two groups.

RESULTS

Compared with healthy counterparts, R-CSAs of total cervical spine muscles, total extensors, superficial extensors, and deep flexors were significantly lower in HD patients. HD patients also demonstrated a significantly greater superficial flexor/superficial extensor CSA ratio than the healthy counterparts, indicating a mismatch between superficial flexors CSA and superficial extensors CSA in HD patients.

CONCLUSIONS

In this pioneering study, HD patients had decreased size in most cervical spine muscles and a mismatch between CSAs of superficial flexor and that of superficial extensors. These results indicate generalized weakness and incongruence of cervical spine muscles, which may predispose cervical spine of HD patients to a less stable situation. These slides can be retrieved under Electronic Supplementary Material.

The effects of deep neck muscle-specific training versus general exercises on deep neck muscle thickness, pain and disability in patients with chronic non-specific neck pain: protocol for a randomized clinical trial (RCT)

BACKGROUND

Altered thickness, cross-sectional area and activity of deep neck muscles have frequently been reported in patients with chronic non-specific neck pain (CNNP). It is claimed that these muscles do not recover spontaneously. These muscles provide a considerable amount of cervical stability. Therefore, various therapeutic exercises have been recommended to recover from resulting complications. However, most exercise protocols do not target deep neck muscles directly. Thus, this might be a reason for long-lasting complications. Accordingly, the purpose of the present study is to discuss a randomized controlled trial (RCT) protocol in which we aim to investigate and compare the effects of neck-specific exercise programmes versus general exercise programmes in patients with CNNP.

METHODS

A 2*2 factorial RCT with before-after design. Sixty-four participants with CNNP will be recruited into the study. They will be randomly divided into two groups, including specific neck exercise and general exercise. Each exercise programme will be carried out three times a week and will last for 8 weeks. Primarily, dorsal and ventral neck muscle thickness, pain and disability and secondarily, muscle strength, quality of life, sleep quality, fear avoidance and neck range of motion will be assessed at the baseline and immediately at the end of the exercise protocol.

DISCUSSION

The results of this study will inform clinicians on which type of exercise is more beneficial for patients with CNNP.

TRIAL REGISTRATION

IRCT2017091620787N2, Sep 16 2017.

Deep flexor sarcopenia as a predictor of poor functional outcome after anterior cervical discectomy in patients with myelopathy

BACKGROUND

Paraspinal muscle morphometry has been recognized to be a prognostic factor across various surgical conditions, but its utility in predicting disease-specific outcomes in spine surgery remains under-explored.

METHODS

A prospective cohort study was performed on 45 consecutive patients undergoing anterior cervical discectomy (ACD) for single-level, symptomatic cervical degenerative disc disease causing radiculomyelopathy or myelopathy. Previously described predictors of outcome such as age, gender, smoking, comorbidities, duration of symptoms, preoperative Nurick grade, extent of cord compression, and signal intensity change in the cord were recorded. Additionally, MRI-based morphometrics of the superficial and deep paraspinal muscles were recorded. Logistic regression (LR) analysis was performed using a purposeful variable selection process to identify variables that independently predicted Nurick grade improvement (NGI).

RESULTS

At a mean follow-up of 20.02 ± 8.63 months after ACD, 37 (82.22%) patients demonstrated NGI. LR analysis yielded three predictors of NGI of which two were related to the deep flexor muscles. While a worse preoperative Nurick grade negatively predicted NGI, a deep flexor area and deep flexor/deep extensor area ratio positively predicted NGI. The regression model demonstrated a good fit and was statistically significant (χ²(3) = 22.18, p < 0.0001). The model explained 64% of the variance in NGI and correctly classified 89% of cases.

CONCLUSIONS

This study has for the first time identified the utility of paraspinal morphometrics in predicting disease-specific functional outcome after cervical spine surgery. Our results indicate that in addition to preoperative Nurick grade, an already accepted outcome predictor, the deep flexor cross-sectional area, and the deep flexor/deep extensor ratio are strong predictors of NGI following ACD for single-level, symptomatic cervical degenerative disc disease with myelopathy. Deep muscle morphometrics could be included in future risk stratification algorithms for patients with cervical disc disease.

Neck Muscle Changes Following Long-Duration Spaceflight

The effects of long-duration spaceflight on crewmember neck musculature have not been adequately studied. The purpose of this study was to evaluate the changes in the neck musculature on pre-flight and post-flight magnetic resonance imaging (MRI) examinations of six crewmembers on 4- to 6-month missions equipped with the advanced resistive exercise device (aRED). The MRI images were resliced to remove variations in spinal curvature, the cross-sectional area (CSA), and muscle fat infiltration (MFI) of neck musculature at the C1-C2, C4-C5, C7-T1, and T1-T2 intervertebral disc levels were measured bilaterally. Percent changes in the neck muscle CSA and fatty infiltration following spaceflight were calculated, and mixed models were used to assess significance of these changes. Crewmembers on missions equipped with the aRED experienced an average 25.1% increase in CSA for the trapezius muscle at C6-C7, an average 11.5% increase in CSA for the semispinalis capitis muscle at C4-C5, an average 9.0% increase in CSA for the sternocleidomastoid muscle at C4-C5, and an average 23.1% increase in CSA for the rhomboid minor at T1-T2. There were no significant changes in the CSA of the levator scapulae, splenius capitis, rectus capitis posterior major, scalenus anterior, scalenus posterior, scalenus medius, longissimus capitis, or obliquus capitis inferior muscles at the locations measured. None of the muscles analyzed experienced statistically significant changes in fatty infiltration with spaceflight. Our study indicates that long-duration spaceflight conditions are associated with preservation of CSA in most neck muscles and significant increases in the CSAs of the trapezius, semispinalis capitis, sternocleidomastoid, and rhomboid minor muscles. This may indicate that cervical muscles are not subjected to the same degradative effects microgravity imparts on the majority of muscles.

Fatty Infiltration of Cervical Spine Extensor Musculature: Is there a Relationship With Cervical Sagittal Balance?

STUDY DESIGN

This is a retrospective review of a single surgeon cervical deformity (CD) database.

OBJECTIVE

Quantitatively describe the cervical extensor musculature in a CD population, and delineate associations between posterior musculature atrophy and progressive sagittal deformity.

SUMMARY OF BACKGROUND DATA

While fatty infiltration (FI; ie, posterior musculature atrophy) of lumbar extensor musculature has been associated with pain and deformity, little is known of the relationship between FI, CD, cervical sagittal alignment, and functionality.

METHODS

CD patients [TS-CL>20 degrees, C2-C7 Cobb>10 degrees, CL>10 degrees, cervical sagittal vertical axis (cSVA)>4 cm, or chin-brow vertical angle>25 degrees] 18 years old and above, undergoing spinal fusion, with baseline T2-weighted magnetic resonance images were included. FI was assessed using dedicated imaging software at each intervertebral level from C2-C7. FI was gauged as a ratio of fat-free muscle cross-sectional area over total muscle cross-sectional area, with lower values indicating increasing FI. Influence of BL C2-C7 FI on patient-reported outcome measures (PROMs) and alignment was investigated. Multiple linear regression analysis (covariates: age, sex, body mass index, C2-C7 FI ratio) determined predictors of postoperative sagittal alignment and PROMs.

RESULTS

Thirty-eight patients were included (age: 56.6, sex: 73.7% female, body mass index: 30.1, Charlson Comorbidity Index 0.61). BL deformity presentation: TS-CL 27.4 degrees, CL 2.1 degrees, cSVA: 27.2 mm. Mean baseline C2-C7 FI ratio was 0.65±0.11. Worsening FI was associated with malaligned baseline cSVA (rs=0.389, P=0.019), T1SS (rs=0.340, P=0.062), and impaired gait (rs=0.358, P=0.078). FI was not associated with BL PROMs (P>0.05). Following surgical intervention, regression models determined BL C2-C7 FI ratio as the strongest predictor of 1-year postoperative cSVA (β=-0.482, P=0.007, R=0.317). No associations between BL FI and postoperative PROMS or alignment parameters were observed (P>0.05).

CONCLUSIONS

Patients with significant CD demonstrate alterations in the posterior extensor musculature of the cervical spine. Atrophic changes with FI of these muscle groups is associated with worsening CD and is an important predictor of postoperative sagittal alignment.

LEVEL OF EVIDENCE

Level III.

Application of MR-derived cross-sectional guideline of cervical spine muscles to validate neck surface electromyography placement

The importance of surface-EMG placement for development and interpretation of EMG-assisted biomechanical models is well established. Since MR has become a reliable noninvasive cervical spine musculoskeletal diagnostic tool, this investigation attempted to illustrate the anatomical relationships of individual cervical spine muscles with their paired surface-EMG electrodes. The secondary purpose of this investigation was to provide an MR cross-sectional pictorial and descriptive guideline of the cervical spine musculature. MR scans were performed on a healthy adult male subject from skull to manubrium of the sternum. Prior to scanning, MR safe markers were placed over neck muscles following surface EMG placement recommendations. Twenty-three neck muscles were traced manually in each of 267 scan slices. 3-D models of the neck musculoskeletal structure were constructed to aid with understanding the complex anatomy of the region as well as to identify correct EMG electrode locations and to identify muscles' curved lines-of-action. 3D models of the MR-safe markers were constructed relative to the target muscles. Based on the findings of this study, muscle palpation and bony landmarks can be used to effectively identify appropriate surface EMG electrode locations to record upper trapezius, middle trapezius, semispinalis capitis, splenius capitis, levator scapulae, scalenus, sternocleidomastoid and hyoid muscles activities.

Criterion Validity of Ultrasound Imaging: Assessment of Multifidi Cross-Sectional Area in Older Adults With and Without Chronic Low Back Pain

BACKGROUND AND PURPOSE

Ultrasound (US) imaging may be a cost-conscious alternative to magnetic resonance imaging (MRI), which is the criterion standard for muscle cross-sectional area (CSA) assessment. Within the trunk, when compared with MRI, US has been shown to be valid for assessing lumbar multifidi CSA in younger, asymptomatic individuals. To date, there are no studies validating US for multifidi CSA assessment in older adults or individuals with low back pain. Given age- and pain-related muscle changes, validation of US is needed in these populations. If valid for multifidi CSA assessment, US may be used to evaluate short-term changes in muscle size in response to exercise-based interventions among older adults. The primary objective of this study was to evaluate the validity of US for multifidi CSA assessment as compared with MRI in older adults with and without chronic low back pain (CLBP). The secondary objective was to determine whether a single US image was valid for assessment of multifidi CSA or whether the average of 3 US images should be recommended.

METHODS

Twenty community-dwelling older adults (ie, 10 with and 10 without CLBP), ages 60 to 85 years, were recruited. US images and MRI slices of multifidi muscle were obtained and L4 multifidi CSAs were measured. Intraclass correlation coefficients (ICCs) were calculated to assess agreement between MRI measures and a single US image and MRI measures and the average of 3 US images.

RESULTS AND DISCUSSION

ICC point estimates were excellent for older adults with CLBP for a single US image (ICCs = 0.90-0.97), but ICC point estimates for participants without CLBP ranged from fair to excellent (ICCs = 0.48-0.86). ICC point estimates for the average of 3 US images for both groups were better than for a single image (ICCs = 0.95-0.99).

CONCLUSIONS

For assessment of L4 multifidi CSA, US is a valid alternative to MRI for older adults with and without CLBP. However, limitations of US, such as the inability to quantify intramuscular fat, which may be increased with aging and CLBP, should be considered. CSA measurement of 3 US images, rather than a single image, is recommended.

Towards defining muscular regions of interest from axial magnetic resonance imaging with anatomical cross-reference: part II - cervical spine musculature

Background

It has been suggested that the quantification of paravertebral muscle composition and morphology (e.g. size/shape/structure) with magnetic resonance imaging (MRI) has diagnostic, prognostic, and therapeutic potential in contributing to overall musculoskeletal health. If this is to be realised, then consensus towards standardised MRI methods for measuring muscular size/shape/structure are crucial to allow the translation of such measurements towards management of, and hopefully improved health for, those with some musculoskeletal conditions. Following on from an original paper detailing methods for measuring muscles traversing the lumbar spine, we propose new methods based on anatomical cross-reference that strive towards standardising MRI-based quantification of anterior and posterior cervical spine muscle composition.

Methods

In this descriptive technical advance paper we expand our methods from the lumbar spine by providing a detailed examination of regional cervical spine muscle morphology, followed by a comprehensive description of the proposed technique defining muscle ROI from axial MRI. Cross-referencing cervical musculature and vertebral anatomy includes an innovative comparison between axial E12 sheet-plastinates derived from cadaveric material to a series of axial MRIs detailing commonly used sequences. These images are shown at different cervical levels to illustrate differences in regional morphology. The method for defining ROI for both anterior (scalenes group, sternocleidomastoid, longus colli, longus capitis) and posterior (multifidus, semispinalis cervicis, semispinalis capitis, splenius capitis) cervical muscles is then described and discussed in relation to existing literature.

Results

A series of steps towards standardising the quantification of cervical spine muscle quality are described, with concentration on the measurement of muscle volume and fatty infiltration (MFI). We offer recommendations for imaging parameters that should additionally inform a priori decisions when planning investigations of cervical muscle tissues with MRI.

Conclusions

The proposed method provides an option rather than a final position for quantifying cervical spine muscle composition and morphology using MRI. We intend to stimulate discussion towards establishing measurement consensus whereby data-pooling and meaningful comparisons between imaging studies (primarily MRI) investigating cervical muscle quality becomes available and the norm.

Quantitative Magnetic Resonance Imaging Analysis of the Cervical Spine Extensor Muscles: Intrarater and Interrater Reliability of a Novice and an Experienced Rater

Study Design

Reliability study.

Purpose

To examine the reliability of novice and experienced raters for measurements of the size and composition of the cervical extensor muscles using a thresholding technique.

Overview of Literature

Although some authors have reported on the dependability of magnetic resonance imaging (MRI) measurements of the cervical muscles, there remains some variability regarding intrarater and interrater reliabilities, and few studies have examined the associated measurement error. Whether the rater's experience noticeably influences the reliability and precision of such measurements has also not been examined.

Methods

A sample of 10 patients with cervical pathologies was selected. Muscle cross-sectional area (CSA), functional cross-sectional area (FCSA), and signal intensity of the cervical extensor muscles were acquired from axial T2-weighted MRIs by a novice and an experienced rater. All measurements were obtained twice, at least 5 days apart, while the raters were blinded to all earlier measurements.

Results

Interrater reliability estimates (intraclass correlation coefficients) varied between 0.84 and 0.99 for the novice rater and between 0.94 and 0.99 for the experienced rater, indicating excellent reliability. The standard error of measurement for the novice rater was, however, noticeably higher for all cervical muscle measurements. Most of the interrater estimates showed excellent agreement with the exception of CSA measurement of the semispinalis cervicis at C4-C7 and FCSA measurement of the multifidus and semispinalis cervicis at C4-C7, which showed poor interrater reliability.

Conclusions

The proposed method of investigating cervical muscle measurements was highly reliable; however, novice raters should receive adequate training before using this method for diagnostic, research, and clinical purposes.

Evidence for cervical muscle morphometric changes on magnetic resonance images after whiplash: A systematic review and meta-analysis

INTRODUCTION

Morphometric changes to cervical musculature in whiplash associated disorder have been reported in several studies with varying results. However, the evidence is not clear because only a limited number of cohorts have been studied and one cohort has been reported in multiple publications. The aim of this study was to assess the evidence for cervical muscle morphometric changes on magnetic resonance (MR) images after whiplash using a systematic review with meta-analysis.

MATERIALS AND METHODS

PubMed, MEDLINE and Cochrane Library were searched without language restriction using combinations of the MeSH terms "muscles", "whiplash injuries", and "magnetic resonance imaging". Studies of acute and chronic whiplash were included if they compared whiplash and control cervical spine muscle morphometry measurements from MR images. The search identified 380 studies. After screening, eight studies describing five cohorts (one acute, three chronic, one both acute and chronic) met the inclusion criteria. Participant characteristics and outcome measures were extracted using a standard extraction format. Quality of eligible studies was assessed using the Newcastle-Ottawa Scale. Muscle cross-sectional area (CSA) and fat infiltrate (MFI) for acute and chronic whiplash cohorts were compared using mean difference and 95% confidence intervals. Meta-analysis models were created when data from more than two eligible cohorts was available, using inverse-variance random-effects models (RevMan5 version 5.3.5).

RESULTS

Quality assessment was uniformly good but only two studies blinded the assessor. Analysis of the acute cohorts revealed no consensus with respect to CSA. MFI was not measured in the acute cohorts. Analysis of the chronic cohorts revealed CSA is probably increased in some muscles after whiplash but there is insufficient evidence to confirm whether MFI is also increased. Because the available data were limited, meta-analyses of only multifidus were performed. In chronic whiplash multifidus CSA was significantly increased at C5 (Z = 3.51, p < 0.01) and C6 (Z = 2.66, p < 0.01); and MFI was significantly increased at C7 only (Z = 2.52, p < 0.01) but the heterogeneity was unacceptably high (I² = 83%).

CONCLUSIONS

The strength of the evidence for cervical muscle morphometric changes on MR images after whiplash is inconsistent for CSA and MFI. Future study designs should be standardised with quantification of three-dimensional muscle morphometry.

Does the mesodermal derangement in Chiari Type I malformation extend to the cervical spine? Evidence from an analytical morphometric study on cervical paraspinal muscles

OBJECTIVE

The mesodermal derangement in Chiari Type I malformation (CMI) has been postulated to encompass the cervical spine. The objectives of this study were to assess the cross-sectional areas (CSAs) of cervical paraspinal muscles (PSMs) in patients with CMI without syringomyelia, compare them with those in non-CMI subjects, and evaluate their correlations with various factors.

METHODS

In this retrospective study, the CSAs of cervical PSMs in 25 patients were calculated on T2-weighted axial MR images and computed as ratios with respect to the corresponding vertebral body areas. These values and the cervical taper ratios were then compared with those of age- and sex-matched non-CMI subjects and analyzed with respect to demographic data and clinicoradiological factors.

RESULTS

Compared with the non-CMI group, the mean CSA values for the rectus capitis minor and all of the subaxial PSMs were lower in the study group, and those of the deep extensors were significantly lower (p = 0.004). The cervical taper ratio was found to be significantly higher in the study cohort (p = 0.0003). A longer duration of symptoms and a steeper cervical taper ratio were independently associated with lower CSA values for the deep extensors (p = 0.04 and p = 0.03, respectively). The presence of neck pain was associated with a lower CSA value for the deep flexors (p = 0.03).

CONCLUSIONS

Patients with CMI demonstrate alterations in their cervical paraspinal musculature even in the absence of coexistent syringomyelia. Their deep extensor muscles undergo significant atrophic changes that worsen with the duration of their symptoms. This could be related to a significantly steeper cervical taper ratio that their cervical cords are exposed to. Neck pain in these patients is related to atrophy of their deep flexor muscles. A steeper cervical taper ratio and alterations in the PSMs could be additional indicators for surgery in patients with CMI without syringomyelia.

Structural changes of the cervical muscles in elder women with cervicogenic headache

BACKGROUND

Evidence suggests that cervicogenic headache is associated with increasing age. Cervical musculoskeletal impairments are common features in individuals with cervicogenic headache. There is some suggestion that the structure (size and fatty infiltration) of neck muscle may factor in or contribute to these impairments.

OBJECTIVE

To investigate relative cross sectional areas (rCSAs) and fatty infiltrate in the cervical muscles in elders with cervicogenic headache compared to controls.

METHODS

Fourteen elder women with cervicogenic headache and 14 controls participated in the study. The rCSAs and fat infiltration were measured for the rectus capitis posterior major, rectus capitis posterior minor, multifidus, semispinalis capitis, splenius capitis, longus capitis/colli, and sternocleidomastoid.

RESULTS

Elder women with cervicogenic headache had significantly reduced rCSAs of the rectus capitis posterior major and multifidus muscles compared to controls (p < 0.05). Larger amounts of fat infiltrates were also observed in the rectus capitis posterior major and minor and splenius capitis muscles in the cervicogenic headache group (p < 0.05). There were no changes in the size and fat infiltrate in the cervical flexor muscles (p > 0.05).

CONCLUSION

The study demonstrated muscle atrophy with increased fatty infiltration in regionally select muscles of the upper and segmental cervical spine in older women with cervicogenic headache. While such changes and their influence on clinical symptoms are unknown, they may have management implications. Future research investigations are required to determine whether such alterations could be modified with specific exercise and modifications to daily living to positively influence clinical symptoms.

Indices of Paraspinal Muscles Degeneration: Reliability and Association With Facet Joint Osteoarthritis: Feasibility Study

STUDY DESIGN

A reliability and cross-sectional observational study.

OBJECTIVE

To introduce a scoring system for visible fat infiltration in paraspinal muscles; to evaluate intertester and intratester reliability of this system and its relationship with indices of muscle density; to evaluate the association between indices of paraspinal muscle degeneration and facet joint osteoarthritis.

SUMMARY OF BACKGROUND DATA

Current evidence suggests that the paraspinal muscles degeneration is associated with low back pain, facet joint osteoarthritis, spondylolisthesis, and degenerative disc disease. However, the evaluation of paraspinal muscles on computed tomography is not radiological routine, probably because of absence of simple and reliable indices of paraspinal degeneration.

METHODS

One hundred fifty consecutive computed tomography scans of the lower back (N=75) or abdomen (N=75) were evaluated. Mean radiographic density (in Hounsfield units) and SD of the density of multifidus and erector spinae were evaluated at the L4-L5 spinal level. A new index of muscle degeneration, radiographic density ratio=muscle density/SD of density, was calculated. To evaluate the visible fat infiltration in paraspinal muscles, we proposed a 3-graded scoring system. The prevalence of facet joint osteoarthritis was also evaluated. Intraclass correlation and κ statistics were used to evaluate inter-rater and intra-rater reliability. Logistic regression examined the association between paraspinal muscle indices and facet joint osteoarthritis.

RESULTS

Intra-rater reliability for fat infiltration score (κ) ranged between 0.87 and 0.92; inter-rater reliability between 0.70 and 0.81. Intra-rater reliability (intraclass correlation) for mean density of paraspinal muscles ranged between 0.96 and 0.99, inter-rater reliability between 0.95 and 0.99; SD intra-rater reliability ranged between 0.82 and 0.91, inter-rater reliability between 0.80 and 0.89. Significant associations (P<0.01) were found between facet joint osteoarthritis, fat infiltration score, and radiographic density ratio.

CONCLUSIONS

Two suggested indices of paraspinal muscle degeneration showed excellent reliability and were significantly associated with facet joint osteoarthritis. Additional studies are needed to evaluate the associations with other spinal degeneration features and low back pain.

Magnetic resonance imaging atlas of the cervical spine musculature

The anatomy of the cervical spine musculature visible on magnetic resonance (MR) images is poorly described in the literature. However, the correct identification of individual muscles is clinically important because certain conditions of the cervical spine, for example whiplash associated disorders, idiopathic neck pain, cervical nerve root avulsion and cervical spondylotic myelopathy, are associated with different morphological changes in specific muscles visible on MR images. Knowledge of the precise structure of different cervical spine muscles is crucial when comparisons with the contralateral side or with normal are required for accurate description of imaging pathology, management and assessment of treatment efficacy. However, learning the intricate arrangement of 27 muscles is challenging. A multi-level cross-sectional depiction combined with three-dimensional reconstructions could facilitate the understanding of this anatomically complex area. This paper presents a comprehensive series of labeled axial MR images from one individual and serves as a reference atlas of the cervical spine musculature to guide clinicians, researchers, and anatomists in the accurate identification of these muscles on MR imaging. Clin. Anat. 29:643-659, 2016. © 2016 Wiley Periodicals, Inc.

Morphological changes in the cervical muscles of women with chronic whiplash can be modified with exercise-A pilot study

INTRODUCTION

In this preliminary study we determined whether MRI markers of cervical muscle degeneration [elevated muscle fatty infiltration (MFI), cross-sectional area (CSA), and reduced relative muscle CSA (rmCSA)] could be modified with exercise in patients with chronic whiplash.

METHODS

Five women with chronic whiplash undertook 10 weeks of neck exercise. MRI measures of the cervical multifidus (posterior) and longus capitus/colli (anterior) muscles, neck muscle strength, and self-reported neck disability were recorded at baseline and at completion of the exercise program.

RESULTS

Overall significant increases in CSA and rmCSA were observed for both muscles, but significant reductions in MFI were only evident in the cervical multifidus muscle. These changes coincided with increased muscle strength and reduced neck disability.

CONCLUSIONS

MRI markers of muscle morphology in individuals with chronic whiplash appear to be modifiable with exercise.

Paraspinal muscle morphometry in cervical spondylotic myelopathy and its implications in clinicoradiological outcomes following central corpectomy

Object

The objective of this study was to assess the cross-sectional areas (CSAs) of the superficial, deep flexor (DF), and deep extensor (DE) paraspinal muscles in patients with cervical spondylotic myelopathy (CSM), and to evaluate their correlations with functional status and sagittal spinal alignment changes following central corpectomy with fusion and plating.

Methods

In this retrospective study of 67 patients who underwent central corpectomy with fusion and plating for CSM, the CSAs of the paraspinal muscles were calculated on the preoperative T2-weighted axial MR images and computed as ratios with respect to the corresponding vertebral body areas (VBAs) and as flexor/extensor CSA ratios. These ratios were then compared with those in the normative population and analyzed with respect to various clinicoradiological factors, including pain status, Nurick grade, and segmental angle change at follow-up (SACF).

Results

The mean CSA values for all muscle groups and the DF/DE ratio were significantly lower in the study cohort compared with an age- and sex-matched normative study group (p < 0.001). Among various independent variables tested in a multivariate regression analysis, increasing age and female sex significantly predicted a lower total extensor CSA/VBA ratio (p < 0.001), while a longer duration of symptoms significantly predicted a greater total flexor/total extensor CSA ratio (p = 0.02). In patients undergoing single-level corpectomy, graft subsidence had a positive correlation with SACF in all patients (p < 0.05), irrespective of the preoperative segmental angle and curvature, while in patients undergoing 2-level corpectomy, graft subsidence demonstrated such a correlation only in the subgroup with lordotic curvatures (p = 0.02). Among the muscle area ratios, the DF/DE ratio demonstrated a negative correlation with SACF in the subgroup with preoperative straight or kyphotic segmental angles (p = 0.04 in the single corpectomy group, p = 0.01 in the 2-level corpectomy group). There was no correlation of any of the muscle ratios with change in Nurick grade.

Conclusions

Patients with CSM demonstrate significant atrophy in all the flexor and extensor paraspinal muscles, and also suffer a reduction in the protective effect of a strong DF/DE CSA ratio. Worsening of this ratio significantly correlates with greater segmental kyphotic change in some patients. A physiological mechanism based on DF dysfunction is discussed to elucidate these findings that have implications in preventive physiotherapy and rehabilitation of patients with CSM. Considering that the influence of a muscle ratio was significant only in patients with hypolordosis, a subgroup that is known to have facetal ligament laxity, it may also be postulated that ligamentous support supersedes the influence of paraspinal muscles on postoperative sagittal alignment in CSM.

Differential changes in muscle composition exist in traumatic and nontraumatic neck pain

STUDY DESIGN

A population based cross-sectional study.

OBJECTIVE

To clarify relative constituents of viable muscle in 2-dimensional cross-sectional area (CSA) measures of ventral and dorsal cervical muscles in patients with chronic whiplash-associated disorders (WAD), idiopathic neck pain, and healthy controls.

SUMMARY OF BACKGROUND DATA

Previous data using T1-weighted magnetic resonance image demonstrated large amounts of neck muscle fat infiltration and increased neck muscle CSA in patients with chronic WAD but not in idiopathic neck pain or healthy controls.

METHODS

Magnetic resonance images were obtained for 14 cervical muscle regions in 136 females, including 79 with chronic whiplash, 23 with chronic idiopathic neck pain, and 34 healthy controls.

RESULTS

Without fat removed, relative CSA of 7 of 14 muscle regions in the participants with chronic WAD was larger, 3 of 14 smaller and 4 of 14 similar to healthy individuals. When T1-weighted signal representing the lipid content of these muscles was removed, 8 of 14 relative muscle CSA in patients with whiplash were similar, 5 of 14 were smaller and only 1 of 14 was larger than those observed in healthy controls. Removal of fat from the relative CSA measurement did not alter findings between participants with idiopathic neck pain and healthy controls.

CONCLUSION

These findings clarify that previous reports of increased relative CSA in patients with chronic whiplash represent cervical muscle pseudohypertrophy. Relative muscle CSA measures reveal atrophy in several muscles in both patients with WAD and idiopathic neck pain, which supports inclusion of muscle conditioning in the total management of these patients.

LEVEL OF EVIDENCE

3.

Correlation of paraspinal atrophy and denervation in back pain and spinal stenosis relative to asymptomatic controls

OBJECTIVE

To determine the relationship among spinal stenosis, back pain, paraspinal muscle denervation, and paraspinal muscle atrophy.

DESIGN

A prospective masked, double-controlled study.

SETTING

A university hospital and outpatient spine clinic.

PARTICIPANTS

Ten asymptomatic subjects, 10 subjects with mechanical low back pain, and 15 subjects with symptomatic spinal stenosis; age range, 55-80 years old.

INTERVENTIONS

Magnetic resonance imaging measurements of minimum spinal canal diameter, paraspinal muscle cross-sectional area at the level of the L5-S1 disk, and quantified paraspinal electrodiagnostic testing (MiniPM) were performed by examiners blinded to each other's results and to the participants' clinical information.

MAIN OUTCOME MEASUREMENTS

Paraspinal muscle cross-sectional area and MiniPM scores.

RESULTS

A paraspinal cross-sectional area decreased significantly from asymptomatic subjects (3872 mm(2)) to subjects with low back pain (3627 mm(2)) and to subjects with spinal stenosis (2985 mm(2)). In the stenosis group, there was a trend toward increased paraspinal denervation in the subjects with severe spinal stenosis, but this was not statistically significant.

CONCLUSIONS

Symptomatic spinal stenosis results in greater paraspinal muscle atrophy than low back pain alone. The extent of paraspinal atrophy was not significantly explained by the extent of denervation, thus, it may be reversible, and the role of paraspinal muscle rehabilitation in patients with spinal stenosis deserves further study.

Cervical muscle area measurements in whiplash patients: Acute, 3, and 6 months of follow-up

PURPOSE

To investigate the role of the cervical spine muscles in whiplash injury. We hypothesized that (i) cervical muscle hypotrophy would be evident after a 6-month follow-up and, (ii) cervical muscle hypotrophy would correlate with symptom persistence probably related to pain or inactivity.

MATERIALS AND METHODS

Ninety symptomatic patients (48 females) were recruited from our emergency department and examined within 48 h, and at 3, and 6 months after a motor vehicle accident. MRI cross-sectional muscle area (CSA) measurements were performed bilaterally of the cervical extensor and sternocleidomastoid muscles using transverse STIR (Short Tau inversion Recovery) sequences at the C2 (deep and total dorsal cervical extensor muscles), C4 (sternocleidomastoid muscles) and C5 (deep and total dorsal cervical extensor muscles) levels. Two blinded raters independently performed the measurements at each time point. First, CSA changes over time were analyzed and, second, CSAs were correlated with clinical outcomes (EuroQuol, Whiplash Disability Score, neck pain intensity [VAS], cervical spine mobility).

RESULTS

There was a high agreement of CSA measurements between the two raters. Women consistently had smaller CSAs than men. There were no significant changes of CSAs over time at any of the three levels. There were no consistent significant correlations of CSA values with the clinical scores at all time points except with the body mass index.

CONCLUSION

Our results do not support a major role of cervical muscle volume in the genesis of symptoms after whiplash injury.

Mechanisms of chronic pain from whiplash injury

This article is to provide insights into the mechanisms underlying chronic pain from whiplash injury. Studies show that injury produces plasticity changes of different neuronal structures that are responsible for amplification of nociception and exaggerated pain responses. There is consistent evidence for hypersensitivity of the central nervous system to sensory stimulation in chronic pain after whiplash injury. Tissue damage, detected or not by the available diagnostic methods, is probably the main determinant of central hypersensitivity. Different mechanisms underlie and co-exist in the chronic whiplash condition. Spinal cord hyperexcitability in patients with chronic pain after whiplash injury can cause exaggerated pain following low intensity nociceptive or innocuous peripheral stimulation. Spinal hypersensitivity may explain pain in the absence of detectable tissue damage. Whiplash is a heterogeneous condition with some individuals showing features suggestive of neuropathic pain. A predominantly neuropathic pain component is related to a higher pain/disability level.

Cross-sectional area of the posterior extensor muscles of the cervical spine in whiplash injury patients versus healthy volunteers--10 year follow-up MR study

INTRODUCTION

Long-term follow-up studies focusing on the posterior extensor muscles in patients suffering from whiplash injury are scarce. The purpose of this study was to elucidate the changes in the posterior extensor muscles 10 years after whiplash injury.

METHODS

Twenty-three patients who had suffered from whiplash injury in 1994-1996 and had undergone MRI using a 1.5-T superconductive imager participated in this follow-up study (13 males, 10 females, mean age 51.8 years, mean follow-up 11.5 years). In addition, 60 healthy volunteers who had undergone MRI in the same period were included as controls (36 males, 24 females, mean age 47.8 years, mean follow-up 11.1 years). All participants underwent follow-up MRI. The cross-sectional areas of the deep posterior muscles (CSA) including the multifidus, semispinalis cervicis, semispinalis capitis, and splenius capitis were digitally measured at C3-4, C4-5, and C5-6 using NIH image. The long-term changes in the CSA were compared between the two groups. In addition, correlations between the CSA and cervical spine-related symptoms were evaluated.

RESULTS

The mean total CSA per patient (the sum of the area from C3-4 to C5-6) was 4811.6±878.4 mm(2) in the whiplash patients and 4494.9±1032.7 mm(2) in the controls at the initial investigation (p=0.20), and 5173.4±946.1 mm(2) and 4713.0±1065.3 mm(2) at the follow-up (p=0.07). The mean change in CSA over time was 361.8±804.9 mm(2) in the whiplash patients and 218.1±520.7 mm(2) in the controls (p=0.34). Ten whiplash patients (43.5%) had neck pain and 11 (47.8%) had shoulder stiffness. However, there was no difference in the change in CSA over time between the symptomatic and asymptomatic patients.

CONCLUSIONS

There was no significant difference in the change in CSA between whiplash patients and healthy volunteers after a 10-year follow-up period. In both groups, the cross-sectional area slightly increased at follow-up. In addition, there was no association between the change in CSA and clinical symptoms such as neck and shoulder pain. These results suggest that whiplash injury is not associated with symptomatic atrophy of the posterior cervical muscles over the long term.

Design and validation of a novel method to measure cross-sectional area of neck muscles included during routine MR brain volume imaging

Introduction

Low muscle mass secondary to disease and ageing is an important cause of excess mortality and morbidity. Many studies include a MR brain scan but no peripheral measure of muscle mass. We developed a technique to measure posterior neck muscle cross-sectional area (CSA) on volumetric MR brain scans enabling brain and muscle size to be measured simultaneously.

Methods

We performed four studies to develop and test: feasibility, inter-rater reliability, repeatability and external validity. We used T1-weighted MR brain imaging from young and older subjects, obtained on different scanners, and collected mid-thigh MR data.

Results

After developing the technique and demonstrating feasibility, we tested it for inter-rater reliability in 40 subjects. Intraclass correlation coefficients (ICC) between raters were 0.99 (95% confidence intervals (CI) 0.98–1.00) for the combined group (trapezius, splenius and semispinalis), 0.92 (CI 0.85–0.96) for obliquus and 0.92 (CI 0.85–0.96) for sternocleidomastoid. The first unrotated principal component explained 72.2% of total neck muscle CSA variance and correlated positively with both right (r = 0.52, p = .001) and left (r = 0.50, p = .002) grip strength. The 14 subjects in the repeatability study had had two MR brain scans on three different scanners. The ICC for between scanner variation for total neck muscle CSA was high at 0.94 (CI 0.86–0.98). The ICCs for within scanner variations were also high, with values of 0.95 (CI 0.86–0.98), 0.97 (CI 0.92–0.99) and 0.96 (CI 0.86–0.99) for the three scanners. The external validity study found a correlation coefficient for total thigh CSA and total neck CSA of 0.88.

Discussion

We present a feasible, valid and reliable method for measuring neck muscle CSA on T1-weighted MR brain scans. Larger studies are needed to validate and apply our technique with subjects differing in age, ethnicity and geographical location.

Cervico-ocular coordination during neck rotation is distorted in people with whiplash-associated disorders

People with whiplash-associated disorders (WAD) not only suffer from neck/head pain, but commonly report deficits in eye movement control. Recent work has highlighted a strong relationship between eye and neck muscle activation in pain-free subjects. It is possible that WAD may disrupt the intricate coordination between eye and neck movement. Electromyographic activity (EMG) of muscles that rotate the cervical spine to the right (left sternocleidomastoid, right obliquus capitis inferior (OI), right splenius capitis (SC) and right multifidus (MF)) was recorded in nine people with chronic WAD. Cervical rotation was performed with five gaze conditions involving different gaze directions relative to cervical rotation. The relationship between eye position/movement and neck muscle activity was contrasted with previous observations from pain-free controls. Three main differences were observed in WAD. First, the superficial muscle SC was active with both directions of cervical rotation in contrast to activity only with right rotation in pain-free controls. Second, activity of OI and MF varied between directions of cervical rotation, unlike the non-direction-specific activity in controls. Third, the effect of horizontal gaze direction on neck muscle EMG was augmented compared to controls. These observations provide evidence of redistribution of activity between neck muscles during cervical rotation and increased interaction between eye and neck muscle activity in people with WAD. These changes in cervico-ocular coordination may underlie clinical symptoms reported by people with WAD that involve visual deficits and changes in function during cervical rotation such as postural control.

The influence of morphology on cervical injury characteristics

STUDY DESIGN

Review of peer-reviewed literature.

OBJECTIVE

Outline the effects of neck and cervical spine morphology on soft tissue injury Potential during low velocity automotive rear impacts.

SUMMARY OF BACKGROUND DATA

Automotive rear impacts are mechanical events and the response of the human head-neck complex can be thought of in biomechanical terms. This manuscript reviews evidence from peer-reviewed studies implicating occupant-related factors in the onset and severity of cervical spine soft-tissue injury.

METHODS

Effects of anatomical characteristics, head-neck and spine orientation, facet joints, and neck muscles were reviewed.

RESULTS

On the basis of existing biomechanically based research, the following occupant-related characteristics can influence the response of the cervical spine during automotive rear impacts: anatomical dimensions of the cervical spine, head-neck and cervical spine orientation at the time of impact, facet joint orientation, and neck muscle size and orientation.

CONCLUSION

The response of the cervical spine to rear impacts can be described using biomechanical concepts. This review has identified occupant-related factors that can influence injury susceptibility and cited biomechanically related research to outline the method by which those factors affect the overall head-neck and cervical spine response in such a way as to increase the susceptibility or severity of injury for a given rear impact event.

Changes in the cross-sectional area of deep posterior extensor muscles of the cervical spine after anterior decompression and fusion: 10-year follow-up study using MRI

PURPOSE

To evaluate changes in the transverse area of deep posterior muscles of the cervical spine 10 years after anterior cervical decompression and fusion (ACDF), in comparison with healthy volunteers.

METHODS

Thirty-one patients (22 males, 9 females, mean age at follow-up 59.3 years, mean follow-up 12.1 years) who had undergone preoperative MRI and non-instrumented ACDF within levels C3-4 to C5-6 were enrolled. 32 asymptomatic volunteers (17 males, 15 females; mean age, 54.7 years; mean follow-up, 11.7 years) who underwent MRI between 1993 and 1996 served as controls. Follow-up MRI was performed on both patients and control subjects, and the cross-sectional areas of deep posterior muscles were measured digitally at levels C3-4, 4-5, and 5-6.

RESULTS

The mean total cross-sectional area in the ACDF and control groups was 4,693.6 ± 1,140.9 and 4,825.8 ± 1,048.2 mm(2) in the first MR study (P = 0.63), and 4,616.7 ± 1,086.0 and 5,036.7 ± 1,105.6 mm(2) at follow-up (P = 0.13). The total cross-sectional area in the ACDF group slightly decreased, while that in the control group increased (-77.1 ± 889.7 vs. 210.9 ± 622.0 mm(2), P = 0.14). The mean change in the cross-sectional area had no significant correlation with clinical symptoms, including neck pain or JOA score.

CONCLUSIONS

ACDF patients did not show a marked decrease in the cross-sectional area of the deep posterior cervical muscles, but as compared with control subjects there was a slight decrease. A decrease in the cross-sectional area of these muscles after ACDF may not result in the axial symptoms as seen in patients treated by posterior surgery.

Cervical muscle area measurements in acute whiplash patients and controls

PURPOSE

To quantitatively compare the muscle cross-sectional areas (CSAs) of the cervical muscles in symptomatic acute whiplash patients versus healthy controls. We hypothesized, that symptomatic whiplash patients have smaller cervical muscle CSAs than matched controls and that smaller cervical muscle CSAs in women might explain that women more frequently are symptomatic after whiplash injury than men.

MATERIALS AND METHODS

Prospective controlled study. Thirty-eight consecutive acute whiplash patients were examined within 48 h after a motor vehicle accident and 38 healthy age- and sex-matched controls, each half female, half male, were examined with the same protocol. MRI CSA measurements were performed of the deep and total cervical extensor muscles as well as the sternocleidomastoid muscles using transversal STIR (Short T1 Inversion Recovery) sequences on level C2, C4, and C5 by two blinded raters. Clinical symptoms were assessed with patient questionnaires (EuroQuol 5D, Specific Whiplash Questionnaire, head- and neck pain intensity [VAS]).

RESULTS

Agreement of measurements between the two raters was high (intraclass correlation 0.52 to 0.85 for the different levels). No significant difference in age and body mass index were seen between patients and controls and the distribution of genders across groups was identical. There were no significant differences between patients and controls for all CSAs. Women had consistently smaller CSAs than men. The CSAs showed no significant correlation with the pain intensity of neck pain and headache but a consistent tendency of less neck pain and more headache with greater CSAs.

CONCLUSION

This small study provides no evidence that subjects with smaller CSAs of cervical extensor muscles have a higher risk in developing symptoms after a whiplash injury and confirms smaller CSA in women.

Cross-sectional area of posterior extensor muscles of the cervical spine in asymptomatic subjects: a 10-year longitudinal magnetic resonance imaging study

There has been no prospective study on age-related changes of the extensor muscles of the cervical spine in healthy subjects. This study was conducted to elucidate any association between the changes in cross-sectional area of the extensor muscles of the cervical spine on MRIs and cervical disc degeneration or the development of clinical symptoms. Sixty-two subjects who underwent MR imaging by a 1.5-Tesla machine between 1993 and 1996 as asymptomatic volunteers in a previous study were recruited again 10 years later for this follow-up study. The mean interval between the studies was 11.0 ± 0.7 years. The cross-sectional areas of the multifidus, semispinalis cervicis, semispinalis capitis, and splenius capitis at C3-C4, C4-C5, and C5-C6 intervertebral levels were measured on T2-weighted axial images using Image J 1.42. The mean cross-sectional areas of the deep extensor muscles were 1,396.8 ± 337.6 mm(2) at the C3-C4 level, 1,514.7 ± 381.0 mm(2) at the C4-C5 level, and 1,542.8 ± 373.5 mm(2) at the C5-C6 level in the previous investigation. The cross-sectional areas were 1,498.7 ± 374.4 mm(2) at the C3-C4 level, 1,569.9 ± 390.9 mm(2) at the C4-C5 level, and 1,599.6 ± 364.3 mm(2) at the 10-year follow-up. An increase in the cross-sectional area of the muscles was more frequently observed in subjects in their tens to thirties in the initial study, while a decrease was more frequently observed in those in their forties and older in the initial study. Disc degeneration was not correlated with a change in extensor muscle volume. Development of shoulder stiffness during follow-up was significantly negatively correlated with a change in the cross-sectional area of the deep extensor muscles.

Changes in mechanical load and extensor muscle activity in the cervico-thoracic spine induced by sitting posture modification

The influence of whole body sitting posture on cervico-thoracic posture, mechanical load and extensor muscle activity was examined in 23 asymptomatic adults. Cervical and upper thoracic extensor muscle activity measured in guided slouched and lumbo-pelvic neutral postures was normalised to that measured in a self-selected habitual posture. Head and neck posture and gravitational load moment measurements were obtained in each posture. Sagittal head translation, upper cervical extension and load moment were significantly greater in the slouched posture (p < 0.001). Contrasting patterns of cervical and thoracic extensor activity were observed in the slouched and neutral postures, with cervical extensor activity 40% higher in the slouched posture (p < 0.0001). Thoracic extensor activity was significantly higher in the lumbo-pelvic neutral posture than the habitual posture (p = 0.002). The significant changes in extensor muscle activity with postural modification appear to be induced by the associated change in mechanical load moment of the head. STATEMENT OF RELEVANCE: More neutral sitting postures reduce the demand on the cervical extensor muscles and modify the relative contribution of cervical and thoracic extensors to the control of head and neck posture. Postures that promote these patterns of muscular activity may reduce cervical spine loading and the development of posture-related neck pain.

The influence of age, anthropometrics and range of motion on the morphometry of the synovial folds of the lateral atlanto-axial joints: a pilot study

The purpose of this study was to investigate the effect of age, anthropometrics and cervical range of motion upon synovial fold volume. Ten healthy female subjects aged 20-40 years were included in the study. Age, height, body mass, dimensions of the head and neck and cervical range of motion of each subject were measured. Magnetic resonance (MR) images of the cervical spine were acquired; the volume of the ventral and dorsal synovial folds of the right and the left lateral atlanto-axial joints was measured using seed growing and thresholding methods. Using Spearman's correlation coefficient, it was determined that there was no correlation between synovial fold volume and age. Synovial fold volume was positively correlated with subject height and neck length but negatively correlated with body mass, body mass index and the circumference of the head and neck. The relationship between synovial fold volume and range of cervical motion varied with the plane of movement. The ability to image the synovial folds of the lateral atlanto-axial joints using MR imaging to determine their normal morphology provides the basis for investigating synovial fold pathology in patients with neck pain and headache.

Magnetic resonance imaging findings of fatty infiltrate in the cervical flexors in chronic whiplash

STUDY DESIGN

Retrospective investigation of muscle changes in patients suffering from chronic whiplash-associated disorders (WAD).

OBJECTIVES

To quantitatively compare the presence of muscle alterations (fatty infiltrate [MFI] and cross-sectional area [CSA]) in the anterior musculature of the cervical spine in a cohort of chronic whiplash patients (WAD II) and healthy control subjects across muscle and cervical segmental level.

SUMMARY OF BACKGROUND DATA

Magnetic resonance imaging can be regarded as the gold standard for muscle imaging. There is little knowledge about in vivo features of anterior neck muscles in patients suffering from chronic WAD and how muscle structure differs across the factors of muscle, vertebral level, age, self-reported pain and disability, body mass index, and duration of symptoms.

METHODS

Reliable magnetic resonance imaging measures for MFI and CSA were performed for the anterior cervical muscles bilaterally in 109 female subjects (78 WAD, 31 healthy control; 18-45 years, 3 months to 3 years postinjury). The measures were performed on all subjects for the longus capitis and colli and the sternocleidomastoid muscles.

RESULTS

The WAD subjects had significantly larger MFI and CSA for the anterior muscles compared to healthy control subjects (all P < 0.0001). In addition, the amount of MFI varied by both cervical level and muscle, with the longus capitis/colli having the largest amount of fatty infiltrates at the C2-C3 level (P < 0.0001). MFI was inversely related to age, self-reported pain/disability, and body mass index but directly proportional to duration of symptoms.

CONCLUSION

There is significantly greater MFI and CSA in the anterior neck muscles, especially in the deeper longus capitis/colli muscles, in subjects with chronic WAD when compared to healthy controls. Future studies are required to investigate the relationships between muscular morphometry and symptoms in patients suffering from acute and chronic WAD.

Changes in paraspinal muscles and their association with low back pain and spinal degeneration: CT study

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.

Synovial folds of the lateral atlantoaxial joints: in vivo quantitative assessment using magnetic resonance imaging in healthy volunteers

STUDY DESIGN

Analysis of magnetic resonance (MR) images of healthy volunteers.

OBJECTIVE

To develop and validate an imaging protocol and measurement technique to describe the morphology and quantify the dimensions of the synovial folds of the lateral atlantoaxial joints in vivo.

SUMMARY OF BACKGROUND DATA

The synovial folds of the lateral atlantoaxial joints are considered to be a potential source of neck pain and headache, especially following whiplash injury. Until recently, it has not been possible to image the synovial folds in vivo and consequently their normal morphology is not fully understood.

METHODS

MR images of the cervical spine of 17 volunteers (4 male and 13 female) were acquired using a 1.5-tesla scanner. The morphology of the synovial folds at the lateral atlantoaxial joints was described and their presence determined. The volume and cross-sectional area of the ventral and dorsal synovial folds of the right and left lateral atlantoaxial joints were measured and compared. The relationship between the dimensions of the synovial folds and subject age was examined. Twenty synovial folds were measured twice by one observer and once by a second observer for the determination of measurement reliability.

RESULTS

There was a significant difference in volume (chi [3] = 17.54, P = 0.000) and cross-sectional area (chi [3] = 18.95, P = 0.000) between the ventral and dorsal synovial folds of the left and right lateral atlantoaxial joints. There was no correlation between synovial fold dimensions and age. The reliability of the measurements ranged from intraclass correlation coefficient 0.95 to 0.99 (intraobserver reliability) and intraclass correlation coefficients 0.75 to 0.82 (interobserver reliability).

CONCLUSION

MR imaging was successfully implemented as a noninvasive method for visualizing the synovial folds of the lateral atlantoaxial joints and quantifying their dimensions in healthy volunteers. The results of this study provide a basis for future studies investigating synovial fold pathology in patients with neck pain and headache.

Cross-sectional area of cervical multifidus muscle in females with chronic bilateral neck pain compared to controls

DESIGN

Case-control study.

OBJECTIVE

To analyze the differences in muscle size and shape of cervical multifidus between patients with bilateral chronic neck pain and healthy subjects.

BACKGROUND

Researchers have demonstrated atrophy of lumbar multifidus in patients presenting with low back pain; however, there are only few published reports on cervical multifidus muscle size in individuals with chronic neck pain.

METHODS AND MEASURES

Bilateral ultrasound images of multifidus muscle from the third to sixth cervical vertebrae (C3 to C6) were taken in 20 women with bilateral chronic neck pain and 20 healthy women. Cross-sectional area (CSA [cm2]) and muscle shape ratio (ratio between lateral [Lat] and anterior-posterior [AP] dimensions, [Lat/AP]) were measured without knowledge of group assignment. Two separate 3-way (4 x 2 x 2) mixed-model analyses of variance (ANOVAs) with cervical level (C3 to C6) and side (right, left) as within-subject factors and group (patient, control) as the between-subject factor, were used to evaluate differences in CSA and muscle shape ratio between groups, sides, and cervical levels.

RESULTS

The ANOVA for CSA indicated a significant effect for cervical level (F = 6.81, P<.001) and group (F = 20.27, P<.001), but not for side (F = 1.26, P = .36). There were no significant interactions among the variables (P>.5). Post hoc analysis showed that the CSA of the C3 multifidus was smaller than the CSA of the C4 (P = .025), C5 (P<.001) or C6 (P<.01) multifidus. There was no significant difference between C4, C5, and C6 multifidus CSA (P>.05). The patients with neck pain had a smaller CSA of the cervical multifidus at all levels compared to controls (P<.001). The ANOVA for muscle shape ratio indicated a significant effect for level (F = 7.84, P<.001) and group (F = 12.501, P<.001), but not for side (F = 0.654, P = .58). There was a significant interaction between level and group (F = 3.651, P = .01). Patients had a wider ovoid shape (greater values in muscle shape ratio) of the C3 (P<.001) and C6 (P<.01) cervical multifidus compared to controls. Further, the C4 multifidus had a smaller shape ratio compared to C6 (P<.001), but was not significantly different than the shape ratio of the C3 and C5 (P>.05) multifidus.

CONCLUSIONS

Females with bilateral chronic neck pain had generalized smaller CSA of the cervical multifidus muscles compared to healthy females.

Association of cross-sectional area of the rectus capitis posterior minor muscle with active trigger points in chronic tension-type headache: a pilot study

OBJECTIVE

To investigate whether cross-sectional area (CSA) of the suboccipital muscles was associated with active trigger points (TrPs) in chronic tension-type headache (CTTH).

DESIGN

Magnetic resonance imaging (MRI) of the cervical spine was performed in 11 females with CTTH aged from 26 to 50 yrs old. CSA for both rectus capitis posterior minor (RCPmin) and rectus capitis posterior major (RCPmaj) muscles were measured from axial T1-weighted images, using axial MRI slices aligned parallel to the C2/3 intervertebral disc. A headache diary was kept for 4 wks to record the pain history. TrPs in the suboccipital muscle were identified by eliciting referred pain to palpation, and increased referred pain with muscle contraction. TrPs were considered active if the elicited referred pain reproduced the head pain pattern and features of the pattern seen during spontaneous headache attacks.

RESULTS

Active TrPs were found in six patients (55%), whereas the remaining five patients showed latent TrPs. CSA of the RCPmin was significantly smaller (F = 13.843; P = 0.002) in the patients with active TrPs (right side: 55.9 +/- 4.4 mm; left side: 61.1 +/-: 3.8 mm) than in patients with latent TrPs (right side: 96.9 +/- 14.4 mm; left side: 88.7 +/- 9.7 mm). No significant differences were found for CSA of the RCPmaj between the patients with either active or latent TrP (P > 0.5).

CONCLUSIONS

It seems that muscle atrophy in the RCPmin, but not in the RCPmaj, was associated with suboccipital active TrPs in CTTH, although studies with larger sample sizes are now required. It may be that nociceptive inputs in active TrPs could lead to muscle atrophy of the involved muscles. Muscle disuse or avoidance behavior can also be involved in atrophy.

Rehabilitative ultrasound imaging: understanding the technology and its applications

The use of ultrasound imaging by physical therapists is growing in popularity. This commentary has 2 aims. The first is to introduce the concept of rehabilitative ultrasound imaging (RUSI), provide a definition of the scope of this emerging tool in regard to the physical therapy profession, and describe how this relates to the larger field of medical ultrasound imaging. The second aim is to provide an overview of basic ultrasound imaging and instrumentation principles, including an understanding of the various modes and applications of the technology with respect to neuromusculoskeletal rehabilitation and in relation to other common imaging modalities.

Magnetic resonance imaging study of the morphometry of cervical extensor muscles in chronic tension-type headache

This study analyses the differences in the relative cross-sectional area (rCSA) of several cervical extensor muscles, assessed by magnetic resonance imaging (MRI), between patients with chronic tension-type headache (CTTH) and healthy controls. MRI of the cervical spine was performed on 15 CTTH females and 15 matched controls. The rCSA values for the rectus capitis posterior minor (RCPmin), rectus capitis posterior major (RCPmaj), semispinalis capitis and splenius capitis muscles were measured from axial T1-weighted images using axial MR slices aligned parallel to the C2/3 intervertebral disc. A headache diary was kept for 4 weeks in order to substantiate the diagnosis and record the pain history. CTTH patients showed reduced rCSA for both RCPmin and RCPmaj muscles (P < 0.01), but not for semispinalis and splenius capitis muscles, compared with controls. Headache intensity, duration or frequency and rCSA in both RCPmin and RCPmaj muscles were negatively correlated (P < 0.05): the greater the headache intensity, duration or frequency, the smaller the rCSA in the RCPmin and RCPmaj muscles. CTTH patients demonstrate muscle atrophy of the rectus capitis posterior muscles. Whether this selective muscle atrophy is a primary or secondary phenomenon remains unclear. In any case, muscle atrophy could possibly account for a reduction of proprioceptive output from these muscles, and thus contribute to the perpetuation of pain.

MRI study of the cross-sectional area for the cervical extensor musculature in patients with persistent whiplash associated disorders (WAD)

Cervical muscle function is disturbed in patients with persistent pain related to a whiplash associated disorder (WAD) but little is known about neck extensor muscle morphometry in this group. This study used magnetic resonance imaging to measure relative cross-sectional area (rCSA) of the rectus capitis posterior minor and major, multifidus, semispinalis cervicis and capitis, splenius capitis and upper trapezius muscles bilaterally at each cervical segment. In total, 113 female subjects (79 WAD, 34 healthy control; 18-45 years, 3 months-3 years post-injury) were recruited for the study. Significant main effects for differences in muscle and segmental level were found between the two groups (P < 0.0001) as well as a significant group * muscle * level interaction (P < 0.0001). The cervical multifidus muscle in the WAD group had significantly larger rCSA at all spinal levels and in contrast, there were variable differences in rCSA measures across levels in the intermediate and superficial extensor muscles when compared to the healthy controls (P < 0.0001). There were occasional weak, although statistically significant relationships between age, body mass index (BMI), duration of symptoms and the size of some muscles in both healthy control and WAD subjects (P < 0.01). It is possible that the consistent pattern of larger rCSA in multifidus at all levels and the variable pattern of rCSA values in the intermediate and superficial muscles in patients with WAD may reflect morphometric change due to fatty infiltrate in the WAD muscles. Future clinical studies are required to investigate the relationships between muscular morphometry, symptoms and function in patients with persistent WAD.