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Purpose: The pathomechanism of dropped head syndrome (DHS) is unclear. In this study, we aimed to examine the features of the paraspinal cervical muscles in patients with DHS by analyzing the volume of these muscles using magnetic resonance imaging (MRI)., Methods: Thirty-six patients with DHS and 25 patients with cervical spondylotic myelopathy (controls) were enrolled. The volume analyzer measured the cross-sectional area (CSA) of the paraspinal muscles on the axial image of a T2-weighted MRI at each level, from C2/3 to C6/7. The histogram used pixel intensities to measure the fat infiltration in the extensor muscles. The data were compared between the groups., Results: The CSA of the semispinalis capitis and the splenius capitis and cervicis from the extensor muscles in DHS was larger than that of the control group at almost all levels. The CSAs of other extensor muscles were equivalent to those of the controls. The CSA of the sternocleidomastoideus in DHS was smaller than in the control group at C4/5/6/7. The CSA of any extensor muscle in the chronic group of the DHS was smaller than that of the acute group at the lower levels. The percentage of fat infiltration was not significantly different between the groups., Conclusion: MRI analyses of the present study revealed that neither the extensor muscles in DHS were atrophic nor the flexor muscles were hypertrophic. Further, fatty infiltration of the extensor muscles may not induce muscle weakness of the extensors in patients with DHS., Competing Interests: Declarations. Conflict of interest: The authors declare no conflicts of interest. Ethical approval: This study was conducted after the protocol had been approved by the Institutional Review Board of Kindai University Hospital (Control Cohort Study, No.2020–25), and informed consent was obtained from all patients. Consent to participate: Informed consent was obtained from all participants included in the study., (© 2025. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: To explore the relationship between paraspinal muscle degeneration and cervical spondylosis through cervical spine MRI and lateral X-ray., Methods: A retrospective study included 83 cervical spondylosis patients as the experimental group, consisting of 28 axial joint pain (Group A), 29 cervical radiculopathy (Group B), and 26 myelopathy (Group C), as well as 29 healthy individuals as the control group (Group D). The cross-sectional area (CSA) of paraspinal muscles at the C3-4, C4-5, and C5-6 segments was measured, including the deep extensor area (DEA), deep flexor area (DFA), and superficial extensor area (SEA). Additionally, fatty infiltration (FI) ratio was calculated, namely the deep extensor fatty infiltration ratio (DEFIR), deep flexor fatty infiltration ratio (DFFIR), and superficial extensor fatty infiltration ratio (SEFIR). Correlations of CSA and FI ratio with age, body mass index, Pfirrmann grading, and Cobb angle were analyzed., Results: (1) Pfirrmann grading in groups A, B, and C was significantly higher than that in group D (P < 0.001), with group C higher than groups A and B (P < 0.05), but the difference between groups A and B was not statistically significant (P > 0.05). (2) There was no significant difference in the CSA among groups (P > 0.05). For DEFIR and DFFIR, group C > group B > group A > group D, with significant differences (P < 0.05). For SEFIR, groups A, B, and C were significantly higher than group D (P < 0.001), with no significant differences between the other pairs (P > 0.05). (3) The CSA of males was significantly greater than females (P < 0.001), while the difference in FI ratio was not significant (P > 0.05). (4) In the control group, DEFIR and DFFIR were positively correlated with age (r = 0.538, P = 0.003; r = 0.829, P < 0.001) and negatively correlated with Cobb angle (r=-0.523, P = 0.004; r=-0.535, P = 0.003). In the experimental group, DEFIR and DFFIR were positively correlated with age (r = 0.731, P < 0.001; r = 0.741, P < 0.001) and Pfirrmann grading (r = 0.778, P < 0.001; r = 0.812, P < 0.001), and negatively correlated with Cobb angle (r=-0.507, P < 0.001; r=-0.539, P < 0.001). There were no correlations between the other parameters., Conclusion: In cervical spondylosis patients, the FI ratio of the deep cervical muscle is linked to both worsening disc degeneration and changes in cervical spine alignment. Among the different subtypes, cervical myelopathy shows the highest FI ratio of the deep cervical muscle and disc degeneration, indicating its significant impact on spinal structure and muscular integrity., Competing Interests: Declarations. Ethical approval: This study was approved by the ethics committee of Second Xiangya Hospital of Central South University (IRB number 2022JJ40696) and was therefore performed in accordance with ethical standards. Competing interests: The authors have no financial or competing interests to disclose in relation to this work., (© 2025. The Author(s).)

Purpose: The purpose was to examine the effects of 8-weeks (3 days/week) of linear periodization resistance exercise training (RET) on neuromuscular function in prepubescent youth., Methods: Twenty-five healthy prepubescent youth (11 males, 14 females, age = 9.1 ± 0.8 years) completed the RET (n = 17) or served as controls (CON, n = 8). Isometric maximal voluntary contractions (MVCs) and trapezoidal submaximal contractions at 35 and 60% MVC of the right leg extensors were performed with surface electromyography (EMG) recorded from the leg extensors [vastus lateralis (VL), rectus femoris, and vastus medialis] and flexors (biceps femoris and semitendinosus). EMG amplitude of the leg extensors and flexors were calculated during the MVCs. Motor unit (MU) action potential trains were decomposed from the surface EMG of the VL for the 35 and 60% MVCs. MU firing rates and action potential amplitudes were regressed against recruitment threshold with the y-intercepts and slopes calculated for each contraction. Total leg extensor muscle cross-sectional area (CSA) was collected using ultrasound images. ANOVA models were used to examine potential differences., Results: Isometric strength increased post-RET (P = 0.006) with no changes in leg extensor and flexor EMG amplitude. Furthermore, there were no changes in total CSA or the MU action potential amplitude vs. recruitment threshold relationships. However, there were increases in the firing rates of the higher-threshold MUs post-RET as indicated with greater y-intercepts (P = 0.003) from the 60% MVC and less negative slope (P = 0.004) of the firing rates vs. recruitment threshold relationships at 35% MVC., Conclusions: MU adaptations contribute to strength increases following RET in prepubescent youth., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: To evaluate the clinical feasibility of atlantoaxial intra-articular cage (AIC) fusion via intermuscular approach for treating reducible atlantoaxial dislocation (AAD)., Methods: An analysis was conducted on the data of 10 patients who underwent C1-C2 segmental fixation and AIC fusion for AAD by unilateral intermuscular approach and contralateral open approach. Outcome assessments included Japanese Orthopaedic Association score (JOA) and Visual Analog Scale Score for Neck Pain (VASSNP). The duration of surgical exposure, screw insertion and cage insertion, and postoperative drainage volume were also compared between two approaches. Bone fusion was evaluated through computed tomography (CT) reconstruction. Postoperative paravertebral tissue edema was evaluated by paravertebral tissue cross-sectional area (CSA) and signal intensity on T2 weighted sequence of magnetic resonance imaging (MRI) at 3 days postoperatively., Results: The intermuscular approach exhibited a longer exposure time but lower drainage postoperatively compared to the open approach (P < 0.05). After operation, JOA scores significant improved (P < 0.05), while VASSNP scores significantly decreased (P < 0.05). There was no significant difference in preoperative CSA between two approaches (P > 0.05). However, compared to the open approach, the intermuscular approach exhibited less CSA (P < 0.05) and lower T2 signal intensity on MRI postoperatively, indicating less invasive to the paravertebral tissues., Conclusions: AIC fusion by intermuscular approach is an effective and safe technique in the treatment of reducible AAD. Intermuscular approach could reduce the postoperative drainage volume and the extent of paravertebral tissue edema compared to open approach., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Validated deep learning models represent a valuable option to perform large-scale research studies aiming to evaluate muscle quality and quantity of paravertebral lumbar muscles at the population level. This study aimed to assess lumbar spine muscle cross-sectional area (CSA) and fat infiltration (FI) in a large cohort of subjects with back disorders through a validated deep learning model., Methods: T2 axial MRI images of 4434 patients (n = 2609 females, n = 1825 males; mean age: 56.7 ± 16.8) with back disorders, such as fracture, spine surgery or herniation, were retrospectively collected from a clinical database and automatically segmented. CSA, expressed as the ratio between total muscle area (TMA) and the vertebral body area (VBA), and FI, in percentages, of psoas major, quadratus lumborum, erector spinae, and multifidus were analyzed as primary outcomes., Results: Male subjects had significantly higher CSA (6.8 ± 1.7 vs. 5.9 ± 1.5 TMA/VBA; p < 0.001) and lower FI (21.9 ± 8.3% vs. 15.0 ± 7.3%; p < 0.001) than females. Multifidus had more FI (27.2 ± 10.6%; p < 0.001) than erector spinae (22.2 ± 9.7%), quadratus lumborum (17.5 ± 7.0%) and psoas (13.7 ± 5.8%) whereas CSA was higher in erector spinae than other lumbar muscles. A high positive correlation between age and total FI was detected (r s  = 0.73; p < 0.001) whereas a negligible negative correlation between total CSA and age was observed (r s  =  - 0.24; p < 0.001). Subjects with fractures had lower CSA and higher FI compared to those with herniations, surgery and with no clear pathological conditions., Conclusion: CSA and FI values of paravertebral muscles vary a lot in accordance with subjects' sex, age and clinical conditions. Given also the large inter-muscle differences in CSA and FI, the choice of muscles needs to be considered with attention by spine surgeons or physiotherapists when investigating changes in lumbar muscle morphology in clinical practice., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: At present, there is a lack of normal magnetic resonance imaging (MRI) morphometric reference values for fetal internal jugular veins during middle and late pregnancy., Objective: We used MRI to assess the morphology and cross-sectional area of the internal jugular veins of fetuses during middle and late pregnancy and to explore the clinical value of these parameters., Materials and Methods: The MRI images of 126 fetuses in middle and late pregnancy were retrospectively analysed to determine the optimal sequence for imaging the internal jugular veins. Morphological observation of the fetal internal jugular veins in each gestational week was carried out, lumen cross-sectional area was measured and the relationship between these data and gestational age was analysed., Results: The balanced steady-state free precession sequence was superior to other MRI sequences used for fetal imaging. The cross section of fetal internal jugular veins was predominantly circular in both the middle and late stages of pregnancy, however the prevalence of an oval cross section was significantly higher in the late gestational age group. The cross-sectional area of the lumen of the fetal internal jugular veins increased with increasing gestational age. Fetal jugular vein asymmetry was common, with the right jugular vein being dominant in the high gestational age group., Conclusion: We provide normal reference values for fetal internal jugular veins measured by MRI. These values may form the basis for clinical assessment of abnormal dilation or stenosis., (© 2023. The Author(s).)

Introduction: Acute subdural hematoma (aSDH) is one of the most devastating entities secondary to traumatic brain injury (TBI). Even though radiological computed tomography (CT) findings, such as hematoma thickness (HT), midline shift (MLS), and MLS/HT ratio, have an important prognostic role, they suffer from important drawbacks. We hypothesized that relative cross-sectional area (rCSA) of specific brain regions would provide valuable information about brain compression and swelling, thus being a key determining factor governing the clinical course., Methods: We performed an 8-year retrospective analysis of patients with moderate to severe TBI with surgically evacuated, isolated, unilateral aSDH. We investigated the influence of aSDH rCSA and ipsilateral hemisphere rCSA along the supratentorial region on the subsequent operative technique employed for aSDH evacuation and patient's clinical outcomes (early death and Glasgow Outcome Scale [GOS] at discharge and after 1-year follow-up). Different conventional radiological variables were also assessed., Results: The study included 39 patients. Lower HT, MLS, hematoma volume, and aSDH rCSA showed a significant association with decompressive craniectomy (DC) procedure. Conversely, higher ipsilateral hemisphere rCSA along the dorso-ventral axis and, specifically, ipsilateral hemisphere rCSA at the high convexity level were predictors for DC. CT segmentation analysis exhibited a modest relationship with early death, which was limited to the basal supratentorial subregion, but could not predict long-term outcome., Conclusion: rCSA is an objectifiable and reliable radiologic parameter available on admission CT that might provide valuable information to optimize surgical treatment., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Muscle strength and function are generally positively correlated with muscle quantity and negatively correlated with muscle quality; however, the tongue shows a unique tendency, different from limb muscles. The relationship between the characteristics of each part of the tongue, muscle strength and function, and systemic factors has been unclear. The aim of the study was to investigate the relationship between cross-sectional area (CSA) and echo intensity (EI) of the middle and base of the tongue and swallowing, articulation function, and body composition. Eighty-nine healthy individuals were included in this cross-sectional study. Swallowing was assessed using tongue pressure (TP) and jaw opening force (JOF) as they indicate swallowing-related muscle strength. Articulation function was evaluated through oral diadochokinesis (ODK). Bioelectrical impedance analysis was performed for body composition. CSAs and EIs of the middle and base of the tongue were measured using ultrasound. Multiple regression analysis was used to examine the relationship between the characteristics of the tongue, swallowing-related muscle strength, and ODK. In multiple regression analysis with TP as the dependent variable, age (β = - 0.22, P < 0.01) and CSA of the middle part (β = 0.02, P < 0.01) were significant explanatory variables. In multiple regression analysis with JOF as the dependent variable, sex (β = - 2.76, P < 0.01) and CSA of the base (β = - 0.004, P < 0.05) were significant explanatory variables. Multiple regression analysis with articulation function as the dependent variable did not yield significant results. The CSA of the tongue is a better indicator of swallowing-related muscle strength than EI. Ultrasonography may be used for assessing swallowing-related muscle strength., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Purpose: The aim of this study was to determine the effect of age on the psoas and posterior paraspinal muscles (PPM; multifidus muscle and erector spinae) and to evaluate potential sex-related differences., Methods: MRI-based quantitative assessments of the cross-sectional area (CSA), the functional cross-sectional area (fCSA), the fat area (FAT) and the proportion of intramuscular fat (FI) were conducted on patients undergoing lumbar fusion surgery between 2014 and 2021. The regions of interest were the psoas muscle and the PPM at the superior endplate of L4. The left and right sides of the muscle groups were summarized and normalized by the patient's height (cm 2 /m 2 ). The relationships between age and muscular parameters were analyzed stratified by sex., Results: A total of 195 patients (57.9%female) with a median age of 64.2 years and a body mass index of 28.3 kg/m 2 were analyzed. The CSA Psoas was 7.7 cm 2 /m 2 and differed significantly between females and males (p < 0.001); likewise, the fCSA Psoas differed significantly between the sexes. The CSA PPM was 18.8 cm 2 /m 2 with no sex-specific differences. Significant differences were found in the FI PPM (males: 41.1% vs. females: 47.9%; p < 0.001), but not in the FI Psoas (males: 3.7% vs. females: 4.5%; p = 0.276). Considering the effect of age on FI, a significant positive correlation was observed for the PPMs for both sexes. Only in women, there was a negative correlation between age and CSA Psoas (ρ =  - 0.248; p = 0.008), FAT Psoas (ρ =  - 0.421; p < 0.001) and FI Psoas (ρ =  - 0.371; p < 0.001)., Conclusion: This study demonstrated sex-specific differences in spinal muscle morphology in relation to patient age. With increasing age there was a decrease in FI Psoas in women only, unlike in the PPMs in which there was increased FI that was significantly higher in women compared to men., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Although changes in muscle morphology and quality in deep neck flexors seem to be clear in patients with whiplash-associated disorders (WAD), evidence for deep neck extensors is heterogeneous. In addition, most studies have used magnetic resonance imaging or computer tomography, which is not available for regular practice., Objectives: To assess differences in deep neck extensors morphology and quality between patients with WAD and controls with ultrasound imaging (US) and to assess the association of imaging findings with clinical features., Methods: One hundred and sixty brightness-mode images at C4/C5 level were acquired in 41 patients with WAD and 39 pain-free controls. Muscle morphology and quality characteristics of the cervical multifidus (CM) and short rotators (SR), clinical pain features and pressure pain thresholds (PPT) were assessed in a blinded design., Results: Between-groups differences in both CM and SR were observed for fatty infiltration percentage (mean: 4.9%; P < 0.001; mean: 3.5%; P < 0.05, respectively) and mean EI (mean: 4.1; P < 0.001; mean: 3.2; P < 0.05, respectively): patients exhibited higher fatty infiltration than controls. The intensity of neck pain was negatively associated with multifidus CSA and perimeter (P < 0.001); symptoms duration was negatively associated with CM morphology (P < 0.001), CM mean EI (P < 0.05) and SR morphology (P < 0.05); pain-related disability was associated with CM morphology (P < 0.001) and SR mean EI (P < 0.05); and PPTs was associated with CM mean EI (P < 0.01) and FI (p < 0.05) and SR morphology (P < 0.001). No significant effect of gender was found in any analysis., Conclusion: US assessment of deep cervical extensors revealed greater fatty infiltration, but no differences in muscle morphology, between WAD patients and pain-free controls., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Although signal intensity on T2W axial images is sensitive in detection of fatty infiltration to assess paraspinal muscle degeneration, it is affected by inhomogeneities of magnetic fields and individual variabilities. The purpose of this study was to propose reference adjusted signal measures on T2W axial images and determine their capacities in reflecting age-related lumbar paraspinal muscle degeneration., Methods: Lumbar MR images of 421 population-based subjects (177 men and 244 women, mean age 53.1 years, range 19.8-87.9 years) were studied. A custom software Spine Explore (Tulong 2.0) was used to automatically obtain paraspinal measurements of multifidus, erector spinae and psoas major. FCSA/TCSA was defined as functional cross-sectional area relative to total cross-sectional area of paraspinal muscle. Two new signal measures were canal-adjusted and cerebrospinal fluid (CSF)-adjusted signal, defined as the ratio between mean signal measurements and the mean signal of the canal and CSF., Results: The raw signal measurements of the paraspinal muscles were weakly correlated to age (r = 0.28-0.39, P < 0.001). When the signal of canal (r = 0.43-0.59, P < 0.001) or CSF (r = 0.45-0.61, P < 0.001) was used as reference, the correlations substantially increased. Signal measurements of three paraspinal muscles, adjusted or not, were strongly associated with Goutallier score (ρ = 0.60-0.65, P < 0.001) and FCSA/TCSA (r = -0.64 to -0.82, P < 0.001). Greater Goutallier score was associated with greater age (r = 0.38-0.60, P < 0.001), while Lumbar indentation value (LIV) not., Conclusion: On routine T2W axial MR images the adjusted signal measurements using an internal reference of CSF or canal can better reflect age-related degenerative changes in the paraspinal muscles., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

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.

Purpose: The purpose of the study was to determine: (1) the relationship between ankle plantarflexor muscle strength and Achilles tendon (AT) biomechanical properties in older female adults, and (2) whether muscle strength asymmetries between the individually dominant and non-dominant legs in the above subject group were accompanied by inter-limb AT size differences., Methods: The maximal generated AT force, AT stiffness, AT Young's modulus, and AT cross-sectional area (CSA) along its length were determined for both legs in 30 women (65 ± 7 years) using dynamometry, ultrasonography, and magnetic resonance imaging., Results: No between-leg differences in triceps surae muscle strength were identified between dominant (2798 ± 566 N) and non-dominant limb (2667 ± 512 N). The AT CSA increased gradually in the proximo-distal direction, with no differences between the legs. There was a significant correlation (P < 0.05) of maximal AT force with AT stiffness (r = 0.500) and Young's modulus (r = 0.414), but only a tendency with the mean AT CSA. However, region-specific analysis revealed a significant relationship between maximal AT force and the proximal part of the AT, indicating that this region is more likely to display morphological adaptations following an increase in muscle strength in older adults., Conclusions: These findings demonstrate that maximal force-generation capabilities play a more important role in the variation of AT stiffness and material properties than in tendon CSA, suggesting that exercise-induced increases in muscle strength in older adults may lead to changes in tendon stiffness foremost due to alterations in material rather than in its size.

Purpose: In this study, we addressed the correlation between the cross-sectional area (CSA) of the dural sac and the nerve root sedimentation sign (SedSign) and the correlation between the distance of claudication and the CSA of the dural sac or SedSign in patients with lumbar spinal stenosis. We also evaluated the reliability of clinical symptom prediction., Methods: We checked claudication distance using a questionnaire, and we gauged low back pain when standing, referred pain, and radiating pain using visual analog scale scores. Three observers measured the CSA of the dural sac and SedSign, and normal nerve root sedimentation was classified as negative (N) and the absence of nerve root sedimentation was positive (P). P was sub-classified as positive with room [P(+); empty space apparent in the dura] or positive without room [P(-); no empty space in the dura]. SedSign reflected ongoing sedimentation inside the spinal canal of the nerve roots. We demonstrated negative sedimentation for the nerve root except for exiting nerve roots that settled into more than half of the dorsal region of the spinal canal and positive sedimentation as compressed nerve roots or as distribution of nerve roots that conglomerated from the ventral to the dorsal part of the equator as nerve roots. We evaluated functional outcomes using the Oswestry Disability Index and Roland-Morris Disability Questionnaire. One-way ANOVAs, Chi square tests, and correlation analyses evaluated the correlation CSAs and SedSigns., Results: The total CSAs for the 716 sites were 98.63 ± 34.38 for N, 76.78 ± 28.78 for P(+), and 55.43 ± 27.77 for P(-), which were all statistically significant (p = 0.01). The correlations between pain and SedSign were not statistically significant (p > 0.05). There was no statistical significance in the correlations between the distance of the claudication and the CSA of the dura sac and the SedSign and between the functional score and the SedSign (both p > 0.05)., Conclusions: Increasing severity of SedSign indicates progressively smaller dural sac CSA, but there is an inconsistent association with clinical symptoms. Therefore, it is reasonable to suggest that spinal stenosis is severe in patients with severe symptoms.

Purpose: This study aimed to examine the reliability of extended field-of-view (EFOV) ultrasound imaging to evaluate the cross-sectional area (CSA) and echo intensity of abdominal skeletal muscles., Methods: Twenty-seven healthy young males (age 18.6 ± 1.0 years, body mass index 20.9 ± 2.8 kg/m 2 , waist circumference 75.0 ± 7.9 cm, body fat 16.6 ± 5.9%) visited the laboratory on 2 days. EFOV ultrasound images of the rectus abdominis, abdominal oblique, and erector spinae muscles were acquired at the height of the third lumbar vertebra with the subject lying on a bed. We then analyzed CSA and echo intensity using ImageJ software and calculated intra-class correlation coefficients (ICC) and the standard error of measurement (SEM)., Results: No significant differences (p = 0.149-0.679) were observed in CSA or echo intensity values for each skeletal muscle between days. ICC and SEM values in CSA for each skeletal muscle ranged between 0.944 and 0.958 and 4.9% and 7.3%, respectively. The corresponding values for echo intensity were 0.851-0.945 for ICC and 5.3-9.7% for SEM., Conclusions: The present results indicate that EFOV ultrasound imaging has high repeatability for measuring CSA and echo intensity of abdominal skeletal muscle groups in healthy college-aged males.

Purpose: To investigate whether pre-operative magnetic resonance imaging (MRI) of the lumbar multifidus muscle (LMM) would predict clinical outcomes following lumbar spinal decompression for symptomatic spinal stenosis., Methods: A prospective cohort of patients with symptomatic neurogenic claudication, documented spinal stenosis on pre-operative MRI underwent spinal decompression. All subjects completed standardised outcome measures (Core Outcome Measures Index (COMI), Oswestry Disability Index (ODI v2.1) pre-operatively, 1 and 2 years post-surgery. Surgery was performed using a standardised lumbar spinous process osteotomy for access, followed by a decompression of the central canal, lateral recess and foraminal zones as indicated by the pre-operative MRI. Lumbar MRI scans were evaluated by two independent observers who assessed the axial CSA of the LMM bilaterally and the degree of muscle atrophy according to the Kader classification (2000). Changes in COMI and ODI scores at 1 and 2 years were investigated for statistically significant correlations with CSA of LMM and Kader grading. Statistical analyses utilised Student's t test, kappa coefficient for inter-observer agreement and Bland-Altman Limits of Agreement (BALOA)., Results: 66 patients (41 female) aged between 29 and 86 years underwent single-level decompression in 44, two-level decompression in 16 and three-level decompression in 6 cases. No significant correlation was observed between improvements in ODI and COMI relative to age, degree of stenosis, posterior fat thickness or psoas CSA. Those subjects with the greatest LMM atrophy relative to psoas CSA and L5 vertebral body area on pre-operative MRI had the least absolute improvement in both ODI and COMI scores (p = 0.006)., Conclusions: Reduced LMM CSA (<8.5 cm 2 ) and muscle atrophy were associated with less favourable outcomes following lumbar spinal decompression. Pre-operative CSA of LMM appeared to be a more reliable predictor of post-operative clinical outcomes compared to the Kader Grading Score. This is the first study to investigate the prognostic value of pre-operative MRI appearance and CSA of LMM with respect to post-operative outcome following lumbar decompression surgery. Healthy pre-operative LMM is associated with better outcomes following lumbar spinal decompression.

Purpose: Lumbar spinal stenosis (LSS) is a disabling condition associated with narrowing of the spinal canal or vertebral foramina. Paraspinal muscle atrophy and fatty infiltration have been reported in patients with chronic LBP and disc herniation. However, very few imaging studies have examined paraspinal muscle morphology and composition in patients with LSS. The purpose of this study was to investigate the association of paraspinal muscle size, composition and asymmetry with functional status in patients with LSS., Methods: Thirty-six patients diagnosed with LSS at L4-L5 with neurogenic claudication were included. Paraspinal muscle measurements were obtained from axial T2-weighted MR images, bilaterally, at the level of the superior and inferior vertebral endplates of L5. Muscle measurements of interest included: total cross-sectional area (CSA), functional CSA (FCSA), the ratio of FCSA to CSA (FCSA/CSA) as an indicator of muscle composition, and relative % asymmetry in muscle CSA. The association between muscle parameters and other patient characteristics with function as indicated from Oswestry Disability Index (ODI) scores and pain interference status was investigated., Results: Greater multifidus muscle fatty infiltration (e.g., lower FCSA/CSA) and lower psoas relative CSA were associated with lower function (higher ODI and pain interference scores) in univariable and multivariable analyses. There was no association between the different muscle parameters and stenosis severity or back or leg pain duration or severity., Conclusions: Our findings suggest an association of multifidus muscle fatty infiltration and psoas muscle size with functional status in patients diagnosed with LSS. Future prospective studies are needed to evaluate whether such muscle parameters are associated with prognosis and functional recovery following surgical treatment.

The purpose of this study was to examine the effects of free leucine supplementation on changes in skeletal muscle mass and strength during a resistance training (RT) program in previously untrained, young subjects. In a double-blind, randomized, placebo-controlled study, 20 healthy young (22 ± 2 years) participants were assigned to two groups: a placebo-supplement group (PLA, N = 10) or a leucine-supplement group (LEU, N = 10). Both groups underwent an 8-week hypertrophic RT program (2 days/week), consuming an equivalent amount of leucine (3.0 g/day in a single post-training dose) or placebo (cornstarch). Quadriceps muscle strength, cross-sectional area (CSA) of the vastus lateralis (VL), and rectus femoris (RF), as well as the habitual dietary intake were assessed before and after the 8-week intervention period. There was a similar improvement in muscle strength (Leg press, LEU: +33% vs. PLA: +37%; P > 0.05, and knee extension, LEU: +31% vs. PLA: 34%; P > 0.05) and CSA (VL, LEU: 8.9% vs. PLA: 9.6%; P > 0.05, and RF, LEU: +21.6% vs. PLA: + 16.4%; P > 0.05) in the both groups from pre- to post-training. In addition, there was no significant (P > 0.05) difference in daily dietary intake between the LEU and PLA groups before and after the intervention period. Free leucine supplementation (3.0 g/day post-training) does not increase muscle strength or CSA during RT in healthy young subjects consuming adequate dietary protein intake.

Purpose: To compare MRI-defined back muscle volume between AS patients and age, and spinopelvic alignment matched control patients with chronic back pain., Methods: 51 male patients with AS were enrolled. Age and spinopelvic alignment matched controls (male) were found among non-AS patients with chronic back pain. After matching procedure, fully matched controls were found in 31 of 51 AS patients (60.8%), who represent AS patients without deformity. However, matched controls were not found in 20 of 51 AS patients (39.2%), who represent AS patients with deformity. MRI parameters of back muscle (paraspinal muscle and psoas muscle) at L4/5 disc level including cross-sectional area (CSA) and fat-free cross-sectional area (FCSA) were compared between AS patients and matched controls. Covariates, including BMI, self-reported physical activity, and the presence of chronic disease, which can influence back muscle volume, were also investigated., Results: There were no statistical differences in age, body mass index, score of back pain (NRS), and spinopelvic alignment, and physical activity between matched AS patients and control patients except for duration of back pain. All MRI parameters for paraspinal muscle volume in matched AS patients (without deformity) were significantly less than those of control patients, and significantly larger than those of non-matched AS patients (with deformity). Body size adjusted MRI parameters (relative CSA and relative FCSA) of paraspinal muscle showed strong correlations with lumbar lordosis and sacral slope. Such relationship between paraspinal muscle and spinopelvic parameters remained significant even after multivariate adjustment., Conclusions: AS patients without deformity already have decreased paraspinal muscle volume compared with age and spinopelvic alignment matched non-AS patients with chronic back pain. Such decrease in paraspinal muscle volume was significantly associated with kyphotic deformity of AS patients even after multivariate adjustment. Although the result of our study supports the causal relationship between muscle degeneration and kyphotic deformity in AS patients, further study is required to prove the causality.

Purpose: We aimed to study generational changes in the dimensions of cervical and lumbar bony spinal canals in Western Switzerland., Methods: A total of 254 patients were retrospectively included, 144 of whom were born during 1940-1949 and 110 during 1970-1979. Cervical spine CTs were performed as part of the spinal clearance procedure following trauma (n = 135) or while investigating neurological symptoms (CT angiography, n = 119). Three independent observers digitally measured the cross-sectional area (CSA) at pedicle levels from C0 to C7 and the anteroposterior diameter (APD) at C3, C5, and C7. In addition, lumbar spine CSAs and APDs were measured on whole body trauma or abdominal CTs, which were also available for 134 patients., Results: Mean CSAs at pedicle levels were numerically smaller in the younger patient group in both cervical and lumbar spine, with the difference reaching statistical significance at all lumbar levels (p ≤ 0.024) except L5. Cervical APDs showed no difference between groups. Subgroup analysis revealed that younger CT angiography patients had a significantly smaller CSA at C1 (p = 0.018) and a similar trend at C4 (p = 0.053). There was moderate positive correlation between cervical and lumbar CSAs, taking C4 and L3 as reference (r = 0.509, p < 0.01)., Conclusions: Younger generation patients have smaller bony spinal canals also in the cervical spine even though this difference is less marked than at the lumbar level. There is, nevertheless, moderate positive correlation between these two anatomical regions. Perinatal factors that adversely influence spinal growth, such as increased maternal age and smoking, could explain these generational changes, given that body height has increased during the same time period. The lesser difference observed in the cervical spine could be due to later closure of the neurocentral synchondrosis at this level.

Purpose: The major aim of this study was to compare ultrasound (US) and magnetic resonance imaging (MRI) measurements of the Achilles tendon cross-sectional area (CSA). Further aims were to conduct reliability analyses and to assess the influence of transducer pressure on the tendon properties in US measurements., Methods: The Achilles tendon CSA of 15 participants was assessed at two positions with US and MRI by use of a standardized protocol. Method comparison was performed by two-way analysis of variance (ANOVA) and paired t test. Reliability was assessed by coefficients of variation (CV), intraclass correlation (ICC 2,2 ), standard error of measurement (SEM), and minimal detectable change (MDC 95 ). A paired t test was performed to investigate the effect of probe pressure on tendon CSA and thickness., Results: Mean US measurements provided a ~5.5% smaller CSA compared to MRI measurements. Intra-rater reliability analyses of US demonstrated CV values of 1.5-4.9%, ICC of 0.89-0.97, SEM and MDC 95 values of 0.22-0.77 mm 2 and 0.61-2.16 mm 2 for both raters, whereby CV values for intra-rater reliability of MRI ranged from 1.0 to 3.7%. Inter-rater reliability was lower for both modalities. Pressure applied on the transducer altered Achilles tendon CSA and thickness significantly (p < 0.05)., Conclusions: Our findings show that US and MRI cannot be used interchangeably for Achilles tendon CSA assessments, however, each imaging modality separately is reliable to assess this property. Pressure applied on the transducer during US measurements causes alterations of the tendon's morphology and should be avoided., Competing Interests: The authors declare that they have no conflict of interest.

Purpose: This study compared maximal eccentric (ECC) and concentric (CON) contractions of the elbow flexors for changes in transverse relaxation time (T2) and indirect markers of muscle damage., Methods: Twelve young men performed five sets of six maximal isokinetic (30°/s) ECC with one arm followed by CON with the other arm. Magnetic resonance images to assess T2 and cross-sectional area (CSA) of biceps brachii, brachialis, and brachioradialis, and measurements of maximal voluntary isometric contraction (MVC) torque, range of motion (ROM), and muscle soreness were taken before, immediately after, and 1, 3, and 5 days after each exercise., Results: MVC torque and ROM decreased greater after ECC than CON (p < 0.05), and muscle soreness developed only after ECC. Biceps brachii and brachialis CSA increased immediately after CON, but delayed increases in brachialis CSA were found only after ECC (p < 0.05). T2 of the muscles increased greater after CON (27-34 %) than ECC (16-18 %) immediately post-exercise (p < 0.05), but returned to baseline by 1 day after CON. The biceps brachii and brachialis T2 increased by 9-29 % at 1-5 days after ECC (p < 0.05). The post-ECC T2 changes showed no significant correlations with the changes in MVC torque, muscle soreness, and CSA, but the T2 increase immediately post-ECC was correlated with the peak T2 in 1-5-day post-ECC (r = 0.63, p < 0.05)., Conclusion: These results suggest that muscle activity during exercise was lower in ECC than CON, and the T2 changes after ECC do not necessarily relate to the changes in other indirect markers of muscle damage.

Purpose: This study examined the relative influence of anatomical and neuromuscular variables on maximal isometric and concentric knee extensor torque and provided a comparative dataset for healthy young males., Methods: Quadriceps cross-sectional area (CSA) and fascicle length (l f) and angle (θ f) from the four quadriceps components; agonist (EMG:M) and antagonist muscle activity, and percent voluntary activation (%VA); patellar tendon moment arm distance (MA) and maximal voluntary isometric and concentric (60° s(-1)) torques, were measured in 56 men. Linear regression models predicting maximum torque were ranked using Akaike's Information Criterion (AICc), and Pearson's correlation coefficients assessed relationships between variables., Results: The best-fit models explained up to 72 % of the variance in maximal voluntary knee extension torque. The combination of 'CSA + θ f + EMG:M + %VA' best predicted maximum isometric torque (R (2) = 72 %, AICc weight = 0.38) and 'CSA + θ f + MA' (R (2) = 65 %, AICc weight = 0.21) best predicted maximum concentric torque., Conclusion: Proximal quadriceps CSA was included in all models rather than the traditionally used mid-muscle CSA. Fascicle angle appeared consistently in all models despite its weak correlation with maximum torque in isolation, emphasising the importance of examining interactions among variables. While muscle activity was important for torque prediction in both contraction modes, MA only strongly influenced maximal concentric torque. These models identify the main sources of inter-individual differences strongly influencing maximal knee extension torque production in healthy men. The comparative dataset allows the identification of potential variables to target (i.e. weaknesses) in individuals.

Purpose: Iatrogenic injuries to paraspinal muscles during the posterior lumbar surgery (PLS) cause a reduction in their cross-sectional areas (CSAs) and contractile densities over time post-surgery. This study aims to quantify such alterations., Method: Pre- and postoperative CSAs (~6 months interval) of all paraspinal muscles were measured in six patients undergoing PLS using a 3-T magnetic resonance (MR) scanner to quantify the alterations in geometrical and tissue effective contractile (non-fatty) CSAs of these muscles at all lumbar levels. To examine the presence of any confounding effects on recorded changes within ~7-month period, measurements were also carried out on ten healthy volunteers., Results: In the healthy population, an important (~22%) portion of CSA of the erector spinae (ES) was noncontractile at the lower lumbar levels. Negligible variations over time in both the total geometrical (<1.7% in average) and contractile (<1.2%) CSAs of muscles were observed in the healthy group (i.e., no confounding effect). Following PLS, significant reductions were observed in the geometrical CSA of only multifidus (MF) muscle by ~14 and 11% as well as in its contractile CSA by ~26 and 14% at the L5-S1 and L4-L5 levels, respectively., Conclusion: The total CSA of ES at lower lumbar levels shows substantial noncontractile contents in both healthy and patient populations. Biomechanical models of the spine should hence account for the noncontractile contents using only the effective contractile muscle CSAs. Postoperative variations in CSAs of paraspinal muscles may have profound effects on patterns of muscle activities, spinal loading, and stability.

Background: Early after intubation, a layer of biofilm covers the inner lumen of the endotracheal tube (ETT). Cleaning the ETT might prevent airways colonization by pathogens, reduce resistance to airflow, and decrease sudden ETT obstruction. We investigated the effectiveness of a cleaning closed suction system in maintaining the endotracheal tube free from secretions., Methods: We conducted a single center, randomized controlled trial, in the general intensive care unit of a tertiary-level university hospital. We enrolled 40 adult critically ill patients expected to remain intubated for more than 48 h, within 24 h from intubation. Patients were randomized to receive three ETT cleaning maneuvers/day using a novel device (Airway Medix Closed Suction System™, cleaning group) or to standard care (no ETT cleaning, standard closed suction, control group). After extubation, the amount of secretions in the ETTs was measured by micro-computed tomography., Results: The volume of secretions in the ETTs from the cleaning group was lower than controls (0.081 [0.021-0.306] vs. 0.568 [0.162-0.756] mL, p = 0.001), corresponding to a cross-sectional area reduction six times lower (1[0-3] vs. 6 [2-10] %, p = 0.001). In a subset of 16 patients, the resistance to airflow tended to be lower after 1 day of treatment (p = 0.063) and was lower after 2 days (0.024), while no difference was present at enrollment (p = 0.922). ETT colonization did not differ between the two groups., Conclusions: The use of a novel cleaning closed suction system proved to be effective in reducing secretions present in the ETT after extubation, possibly reducing resistance to airflow during intubation., Trial Registration: clinicaltrials.gov NCT01912105.