The influence of anterior cervical discectomy and fusion surgery on cervical muscles and the correlation between related muscle changes and surgical efficacy.

BACKGROUND: Anterior cervical discectomy and fusion surgery (ACDF) is a common technique in treating degenerative cervical spondylosis. This study is to evaluate the changes of cervical muscles after ACDF and analyze the correlation between related muscle changes and clinical efficacy. METHODS: Sixty-five postoperative patients (single-level ACDF) with cervical spondylotic myelopathy from January 2013 to December 2022 were analyzed. The measured parameters include: the axial section of longus colli cross-sectional area (AxCSA), the volume of cervical longus, the ratio of long and short diameter line (RLS), the cervical extensor cross-sectional area (CESA), the vertebral body area (VBA), and the CESA/VBA. The visual analog scale (VAS), modified Japanese Orthopedic Association score (mJOA), and neck disability index (NDI) were evaluated. The changes in muscle morphology were analyzed, and the correlation analysis was conducted between morphological changes and function scores. RESULTS: The postoperative AxCSA of surgical segment (3rd month, 12th month, and the last follow-up) was decreased compared to preoperative (141.62 ± 19.78), and the differences were significant (P < 0.05). The corresponding data reduced to (119.42 ± 20.08) mm2, (117.59 ± 19.69) mm2, and (117.41 ± 19.19) mm2, respectively (P < 0.05). The RLS increased, and the volume of cervical longus decreased significantly after surgery (P < 0.05). Negative correlation was found between postoperative volume of cervical longus and VAS at the 3rd month (r = - 0.412), 12th month (r = - 0.272), and last follow-up (r = - 0.391) (P < 0.05). Negative correlation existed between postoperative volume of cervical longus and NDI at the 3rd month (r = - 0.552), 12th month (r = - 0.293), and last follow-up (r = - 0.459) (P < 0.05). CONCLUSION: The volume of cervical longus decreased and its morphology changed after ACDF surgery. The mainly affected muscle was the cervical longus closing to the surgical segment. Negative correlation was found between the postoperative volume of cervical longus and function scores (VAS and NDI).

Vibration training and quadriceps muscle strength in soccer players' knee joints

Objective: This paper discusses the effect of vibration training on the strength of knee flexion and extension muscle group of football players. Methods: This test was carried out in a local sports college from January 2021 to January 2022. Taking 22 football playersin the college as an example, the athletes were divided into experimental group and observation group by digital grouping method, with 11 people in each group. The observation group was trained with the conventional lower limb physical training method, but also on the equipment. In the process of the experiment, the researchers will focus on the analysis of vibration training on the knee flexion and extension muscle group of football players, and compare the data and effects of the two groups of athletes. The experiment lasted for eight weeks. Results:The data of the experimental group were better than those of the observation group. Vibration training had a significant effect on improving the muscle strength of knee flexion and extension muscle group of football players, P > 0.05. Conclusion:In this eight-week experiment, the vibration training program with 30Hz frequency and 2mm amplitude can significantly improve the muscle strength of knee flexion and extension muscles of college athletes. Compared with the traditional training method, the vibration training program has more advantages, mainly reflected in the tolerance of athletes. However, there is little difference between the method and the traditional training method in the athlete's explosive power, and no great advantage is seen (AU)

Effects of Cervical Paravertebral Extensors in Patients with Cervical Ossification of the Posterior Longitudinal Ligament Grouped According to mK-Line.

OBJECTIVES: The objective of this study was to quantify the morphology, composition, and asymmetry of the paravertebral extensor muscles (PSEMs) in patients with cervical ossification of the posterior longitudinal ligament (OPLL) who had different modified K-line (mK-line) and the minimum interval between the mK-line and OPLL (INTmin ) values and to investigate the relationship between PSEMs and symptoms and outcomes following laminoplasty. These original findings elucidated that the atrophy of PSEMs could predict decompression outcomes and provided a theoretical basis for paraspinal muscle rehabilitation. METHODS: A total of 94 consecutive patients who underwent laminoplasty for OPLL between January 2020 and January 2022 were enrolled in this retrospective study. The relative cross-sectional areas (rCSA), functional cross-sectional areas (rFCSA), and FCSA/CSA ratio of the multifidus (MF), semispinalis cervicalis (SSCe), semispinalis capitis (SSCa), and splenius capitis (SpCa) were measured at the C3-C7 segments on cervical magnetic resonance imaging (MRI). This study compared the differences between the mK-line (+) group and the mK-line (-) group, as well as between the INTmin <4 mm group and the INTmin ≥4 mm group, using the independent t-test or Mann-Whitney test for continuous variables and the χ2 -test for categorical variables. The correlations between the PSEMs and symptoms were analyzed using either the Pearson or Spearman correlation coefficient. RESULTS: The relative total CSA (rTCSA) of the PSEMs, especially the MF, was significantly smaller in the mK-line (-) group. However, the FCSA/CSA of the right deep extensor muscle (DEM) was larger. The asymmetry of the MF TFCSA/TCSA showed a significant difference between the mK-line groups. In the INTmin <4 mm group, the PSEMs rCSA and rFCSA were significantly smaller, while the bilateral MF TFCSA/TCSA and right SSCe TFCSA/TCSA were larger. The asymmetry of the superficial extensor muscle rCSA was significantly lower in the group with INTmin <4 mm. The postoperative modified Japanese Orthopedic Association score (mJOA) and mJOA recovery rate were positively correlated with the INTmin and DEM rCSA and negatively correlated with the asymmetry of MF FCSA/CSA. CONCLUSIONS: In patients with mK-line (-) or INTmin <4 mm, the PSEMs were smaller, and the DEM atrophy and composition changes were predominant. The MF asymmetry was higher in patients with mK-lines (-), whereas the SEM atrophy and asymmetry were more prevalent in patients with INTmin <4 mm. The DEM was related to the preoperative and postoperative mJOA scores. DEM-preserving surgery or DEM-specific rehabilitation exercises can improve the recovery of patients with OPLL during the perioperative period. In addition, attention should be paid to the evaluation of the SEM, especially the SpCa at the C3 and C5 levels.

Cervical muscle morphometry and composition demonstrate prognostic value in degenerative cervical myelopathy outcomes.

Objectives: This study aimed to examine whether preoperative cervical muscle size, composition, and asymmetry from magnetic resonance imaging (MRI) can predict post-operative outcomes in patients with degenerative cervical myelopathy (DCM). Methods: A total of 171 patients with DCM were included. Relative total cross-sectional area (RCSA), functional CSA (fat-free area, FCSA), ratio of FCSA/CSA (fatty infiltration) and asymmetry of the multifidus (MF) and semispinalis cervicis (SCer) together (MF + SCer), and cervical muscle as a group (MF, SCer, semispinalis capitis, and splenius capitis) were obtained from T2-weighted axial MR images at the mid-disk, at the level of maximum cord compression and the level below. Univariate and multivariate linear regression analyses were used to assess the relationship between baseline cervical muscle measurements of interest with the modified Japanese Orthopedic Association (mJOA), Nurick Classification, Neck Disability Index (NDI), and SF-36 health survey at 6-month and 12-month post-surgery. Results: Lower RCSA of MF + SCer, less CSA MF + SCer asymmetry and greater FCSA/CSA for the cervical muscle group (e.g., less fatty infiltration), and younger age were significant predictors of higher mJOA scores (e.g., less disability) at 6-month and 12-month post-surgery (all p < 0.05). Greater CSA asymmetry in MF + SCer and lower FCSA/CSA (e.g., more fatty infiltration) for the cervical muscle group were significant predictors of higher Nurick scores (e.g., more disability) at 6-month and 12-month post-surgery (all p < 0.05). Lower FCSA MF + Scer asymmetry, lower FCSA/CSA asymmetry of the muscle group, and greater RCSA MF + SCer were significant predictors of higher NDI scores at 6-month and 12-month post-surgery. Finally, greater FCSA/CSA asymmetry of the MF + SCer, greater FCSA asymmetry of the muscle group, greater RCSA of the muscle group, and greater CSA asymmetry of MF + SCer were significant predictors of lower post-operative SF-36 scores at 6- and 12-month post-surgery. Conclusion: Our result suggested that cervical paraspinal muscle morphology, specifically greater asymmetry, and fatty infiltration may be important predictors of functional recovery and post-surgical outcomes in patients with DCM.

Exercise therapy including the cervical extensor muscles in individuals with neck pain: A systematic review.

OBJECTIVE: To review the use (dosage parameters and combination with other therapeutic interventions) of cervical extensor muscle exercises and their effect on pain, disability (primary outcomes), range of motion, endurance and strength (secondary outcomes) in people with neck pain. DATA SOURCES: An extensive literature search was conducted through MEDLINE (Ovid), Scopus (Elsevier) and Physiotherapy Evidence Database (PEDro) up to May 2023. The reference lists of all included studies and relevant reviews were screened for additional studies. REVIEW METHODS: Randomised controlled trials reporting the use of cervical extensor muscle exercises (alone or combined) applied to adults with idiopathic or traumatic neck pain were included. Study selection, data extraction and critical appraisal (PEDro assessment scale) were performed by two blinded reviewers. Data extraction included dosage parameters, other modalities combined with these exercises and outcomes. RESULTS: Thirty-five randomised controlled trails (eight of which were complementary analyses) with 2409 participants fulfilled the inclusion criteria. Twenty-six were of moderate to high quality. In most studies, cervical extensor muscle exercises were combined with various other therapeutic modalities and applied at different dosages. Only two studies (one high and one low quality) specifically assessed their effectiveness. The high-quality study showed significant improvements in neck pain and disability, pressure point threshold and neck mobility after both low load and high load training for 6 weeks. CONCLUSION: The results suggest cervical extensor muscle exercises may reduce neck pain and disability; however firm conclusions cannot be drawn because of the few studies that addressed this question and the heterogeneity of the dosage parameters.

Pervasive and diffuse muscle activity during REM sleep and non-REM sleep characterises multiple system atrophy in comparison with Parkinson's disease.

Multiple system atrophy (MSA) and Parkinson's disease (PD) may share overlapping features particularly at early disease stage, including sleep alterations, but have profoundly different prognoses. Certain sleep phenomena and disorders of motor control are more prevalent in multiple system atrophy, such as REM sleep behaviour disorder (RBD). We quantitatively tested whether pervasive muscle activity during sleep occurs in subjects with multiple system atrophy versus Parkinson's disease. Laboratory polysomnographic studies were performed in 50 consecutive subjects with Parkinson's disease and 26 age- and gender-matched subjects with multiple system atrophy at <5 years from disease onset. The distributions of normalised electromyographic activity of submentalis, wrist extensor, and tibialis anterior muscles in different wake-sleep states during the night were analysed. Subjects with multiple system atrophy had significantly higher activity of submentalis, wrist extensor, and tibialis anterior muscles than subjects with Parkinson's disease during non-REM sleep, including separately in stages N1, N2, and N3, and during REM sleep, but not during nocturnal wakefulness. The activity of wrist extensor and tibialis anterior muscles during non-REM sleep and the activity of tibialis anterior muscles during REM sleep were also significantly higher in subjects with multiple system atrophy and RBD than in subjects with Parkinson's disease and RBD. In conclusion, with respect to Parkinson's disease, multiple system atrophy is characterised by a pervasive and diffuse muscle overactivity that involves axial and limb muscles and occurs not only during REM sleep, but also during non-REM sleep and between subjects with comorbid RBD.

Spinal premotor interneurons controlling antagonistic muscles are spatially intermingled.

Elaborate behaviours are produced by tightly controlled flexor-extensor motor neuron activation patterns. Motor neurons are regulated by a network of interneurons within the spinal cord, but the computational processes involved in motor control are not fully understood. The neuroanatomical arrangement of motor and premotor neurons into topographic patterns related to their controlled muscles is thought to facilitate how information is processed by spinal circuits. Rabies retrograde monosynaptic tracing has been used to label premotor interneurons innervating specific motor neuron pools, with previous studies reporting topographic mediolateral positional biases in flexor and extensor premotor interneurons. To more precisely define how premotor interneurons contacting specific motor pools are organized, we used multiple complementary viral-tracing approaches in mice to minimize systematic biases associated with each method. Contrary to expectations, we found that premotor interneurons contacting motor pools controlling flexion and extension of the ankle are highly intermingled rather than segregated into specific domains like motor neurons. Thus, premotor spinal neurons controlling different muscles process motor instructions in the absence of clear spatial patterns among the flexor-extensor circuit components.

The spinal cord contains circuits of nerve cells that control how the body moves. Within these networks are interneurons that project to motor neurons, which innervate different types of muscle to contract: flexors (such as the biceps), which bend, or 'flex', the body's joints, and extensors (such as the triceps), which lead to joint extension. These motor signals must be carefully coordinated to allow precise and stable control of the body's movements. Previous studies suggest that where interneurons are placed in the spinal cord depends on whether they activate the motor neurons responsible for flexion or extension. To test if these findings were reproducible, Ronzano, Skarlatou, Barriga, Bannatyne, Bhumbra et al. studied interneurons which flex and extend the ankle joint in mice. In collaboration with several laboratories, the team used a combination of techniques to trace how interneurons and motor neurons were connected in the mouse spinal cord. This revealed that regardless of the method used or the laboratory in which the experiments were performed, the distribution of interneurons associated with flexion and extension overlapped one another. This finding contradicts previously published results and suggests that interneurons in the spinal cord are not segregated based on their outputs. Instead, they may be positioned based on the signals they receive, similar to motor neurons. Understanding where interneurons in the spinal cord are placed will provide new insights on how movement is controlled and how it is impacted by injuries and disease. In the future, this knowledge could benefit work on how neural circuits in the spinal cord are formed and how they can be regenerated.

Low back muscle action potential conduction velocity estimated using high-density electromyography.

While a decreasing spectral content of surface electromyography reflects low back muscle fatigue development, reliability of these decreases may be insufficient. Decreasing frequency content is largely determined by decreasing average motor unit action potential conduction velocities (CV), which is considered a more direct measure of muscle fatigue development. However, for the low back muscles it has been proven difficult to identify propagating potentials and consequently estimate the CV. The aim of this study was to estimate the low back muscle CV from high-density multi-channel electromyography by using peak-delay and cross-correlation methods. Fourteen healthy male participants without a history of low-back pain performed a 30 degrees lumbar flexion trial until exhaustion while standing. For 10 out of the 14 participants (118 out of 560 sites) realistic CV estimates were obtained using both methods, the majority likely over the iliocostalis lumborum muscle. Between-method CV differences appeared to be small. Close to the spine a considerable number of sites (79) yielded systematically overestimated low back muscle CV values. Estimating low back muscle CV may allow additional insight into low back muscle fatigue development and potentially improve its monitoring using (high-density) surface electromyography.

Increased Stiffness of the Superficial Cervical Extensor Muscles in Patients With Cervicogenic Headache: A Study Using Shear Wave Elastography.

Background: Cervicogenic headache (CEH) is a secondary headache caused by lesions of the cervical spine and surrounding soft tissues. Cervical muscle dysfunction may be related to the onset of CEH. However, whether cervical muscle stiffness changes in patients with CEH has not been well studied. The purpose of this study was to explore changes in superficial cervical extensor muscle stiffness in patients with CEH using shear wave elastography (SWE). Methods: In this study, 19 patients with CEH and 20 healthy controls were recruited. Superficial cervical extensor muscle stiffness was obtained from SWE, and the SuperLinear SL10-2 MHz linear array probe in the musculoskeletal muscle mode was chosen as the transducer. Regions of interest in the trapezius (TRAP), splenius capitis (SPL), semispinalis capitis (SCap), and semispinalis cervicis (SCer) were manually segmented. Correlations between superficial cervical extensor muscle stiffness and visual analog scale (VAS) scores, age, and body mass index (BMI) were analyzed using Pearson's correlation. Receiver operating characteristic (ROC) curve was used to investigate the diagnostic ability of superficial cervical extensor stiffness for CEH. Results: Superficial cervical extensor muscle stiffness on the headache side of patients with CEH was higher than that on the non-headache side and in healthy controls (p < 0.05). Increased stiffness was also observed in SCer on the non-headache side of patients with CEH compared to healthy controls (p < 0.01). In patients with CEH, SCer stiffness was positively correlated with VAS scores (r = 0.481, p = 0.037), but no correlation was found between other muscles and VAS scores (p > 0.05). The areas under the curve of TRAP, SPL, SCap, and SCer in diagnosing CEH were 0.766, 0.759, 0.964, and 1.000, respectively. Conclusions: Increased stiffness was observed in the superficial cervical extensor muscles on the headache side of patients with CEH. SCer stiffness was correlated with headache intensity in patients with CEH and may provide clues for the diagnosis of CEH.

Corticospinal Excitability Is Lower During Eccentric Than Concentric Cycling in Men.

How corticospinal excitability changes during eccentric locomotor exercise is unknown. In the present study, 13 volunteers performed 30-min strenuous concentric and eccentric cycling bouts at the same power output (60% concentric peak power output). Transcranial magnetic and electrical femoral nerve stimulations were applied at exercise onset (3rd min) and end (25th min). Motor-evoked potentials (MEPs) amplitude was measured for the rectus femoris (RF) and vastus lateralis (VL) muscles with surface electromyography (EMG) and expressed as a percentage of maximal M-wave amplitude (MMAX). EMG amplitude 100 ms prior to MEPs and the silent period duration were calculated. There was no change in any neural parameter during the exercises (all P > 0.24). VL and RF MMAX were unaffected by exercise modality (all P > 0.38). VL MEP amplitude was greater (26 ± 11.4 vs. 15.2 ± 7.7% MMAX; P = 0.008) during concentric than eccentric cycling whereas RF MEP amplitude was not different (24.4 ± 10.8 vs. 17.2 ± 9.8% MMAX; P = 0.051). While VL EMG was higher during concentric than eccentric cycling (P = 0.03), RF EMG showed no significant difference (P = 0.07). Similar silent period durations were found (RF: 120 ± 30 ms; VL: 114 ± 27 ms; all P > 0.61), but the silent period/MEP ratio was higher during eccentric than concentric cycling for both muscles (all P < 0.02). In conclusion, corticospinal excitability to the knee extensors is lower and relative silent period longer during eccentric than concentric cycling, yet both remained unaltered with time.

Test-retest reliability of a load cell setup, Ito, and timed loaded standing tests for measuring muscle strength and endurance in older adults with and without hyperkyphosis.

BACKGROUND: The association of back muscle weakness with greater thoracic kyphosis has been widely documented. Reliable and easy-to-use techniques are needed to monitor changes in muscle function over time and assess the effectiveness of therapeutic interventions. Therefore, the present study aimed to evaluate the test-retest reliability of a designed load-cell setup and two clinical tests, namely Ito and Timed loaded standing (TLS) tests for measuring back muscle function (i.e., strength and endurance) in older adults with and without hyperkyphosis. METHOD: Fifty-three older people (28 with thoracic hyperkyphosis and 25 normal age-matched controls) completed the present test-retest reliability study. A two-way random model of the Intraclass Correlation Coefficient (ICC2,3) was used to estimate relative reliability. Absolute reliability was assessed by calculating Standard Error of the Measurements (SEM) and Minimal Detectable Change (MDC). RESULTS: The findings showed excellent test-retest reliability in all performed tests for this population (ICC = 0.95-0.99). In addition, the MDC values for measuring endurance time via load cell, Ito, and TLS tests in the hyperkyphosis group, were 16.5, 28.2, and 35.1 s, respectively. These values ranged from 36 to 39 s for the control group. CONCLUSION: The present study suggests high test-retest reliability of the designed load-cell setup, Ito, and TLS for assessing back extensor muscle strength and endurance in older adults with and or without hyperkyphosis.

The association of reactive balance control and spinal curvature under lumbar muscle fatigue.

BACKGROUND: Although low back fatigue is an important intervening factor for physical functioning among sedentary people, little is known about its possible significance in relation to the spinal posture and compensatory postural responses to unpredictable stimuli. This study investigates the effect of lumbar muscle fatigue on spinal curvature and reactive balance control in response to externally induced perturbations. METHODS: A group of 38 young sedentary individuals underwent a perturbation-based balance test by applying a 2 kg load release. Sagittal spinal curvature and pelvic tilt was measured in both a normal and Matthiass standing posture both with and without a hand-held 2 kg load, and before and after the Sørensen fatigue test. RESULTS: Both the peak anterior and peak posterior center of pressure (CoP) displacements and the corresponding time to peak anterior and peak posterior CoP displacements significantly increased after the Sørensen fatigue test (all at p < 0.001). A lumbar muscle fatigue led to a decrease of the lumbar lordosis in the Matthiass posture while holding a 2 kg load in front of the body when compared to pre-fatigue conditions both without a load (p = 0.011, d = 0.35) and with a 2 kg load (p = 0.000, d = 0.51). Also the sacral inclination in the Matthiass posture with a 2 kg additional load significantly decreased under fatigue when compared to all postures in pre-fatigue conditions (p = 0.01, d = 0.48). Contrary to pre-fatigue conditions, variables of the perturbation-based balance test were closely associated with those of lumbar curvature while standing in the Matthiass posture with a 2 kg additional load after the Sørensen fatigue test (r values in range from -0.520 to -0.631, all at p < 0.05). CONCLUSION: These findings indicate that lumbar muscle fatigue causes changes in the lumbar spinal curvature and this is functionally relevant in explaining the impaired ability to maintain balance after externally induced perturbations. This emphasizes the importance for assessing both spinal posture and reactive balance control under fatigue in order to reveal their interrelations in young sedentary adults and predict any significant deterioration in later years.

Non-uniform upregulation of the autogenic stretch reflex among hindlimb extensors following lateral spinal lesion in the cat.

Successful propagation throughout the step cycle is contingent on adequate regulation of whole-limb stiffness by proprioceptive feedback. Following spinal cord injury (SCI), there are changes in the strength and organization of proprioceptive feedback that can result in altered joint stiffness. In this study, we measured changes in autogenic feedback of five hindlimb extensor muscles following chronic low thoracic lateral hemisection (LSH) in decerebrate cats. We present three features of the autogenic stretch reflex obtained using a mechanographic method. Stiffness was a measure of the resistance to stretch during the length change. The dynamic index documented the extent of adaptation or increase of the force response during the hold phase, and the impulse measured the integral of the response from initiation of a stretch to the return to the initial length. The changes took the form of variable and transient increases in the stiffness of vastus (VASTI) group, soleus (SOL), and flexor hallucis longus (FHL), and either increased (VASTI) or decreased adaptation (GAS and PLANT). The stiffness of the gastrocnemius group (GAS) was also variable over time but remained elevated at the final time point. An unexpected finding was that these effects were observed bilaterally. Potential reasons for this finding and possible sources of increased excitability to this muscle group are discussed.

Expansion of Spinal Canal with Lift-Open Laminoplasty: A New Method for Compression Cervical Myelopathy.

OBJECTIVE: This study is to introduce lift-open laminoplasty and verify the increase of the spinal canal area following this surgical technique according to the preoperative anatomical measurement. METHODS: There are 82 patients (43 male and 39 female) analyzed in our study from January 2019 to December 2020. The average age was 63.2 ± 3.21 years (from 41 to 84 years). All of them were treated with open-door laminoplasty, with a decompression segment range from C3 to C6. The increase of the spinal canal area after open-door laminoplasty was measured on postoperative CT images of the patients, and the distances between both lamina-facet junctions and lamina length was measured on preoperative CT images. Using the Pythagorean theorem for the equation of calculation area after the expansile open-door laminoplasty. Based on previous measurement parameters, spinous process length, lateral mass width, distance between osteotomy line and lamina-facet junctions line were additionally measured on preoperative CT images. Pythagorean theorem was used for calculating the area after the expansile lift-open laminoplasty. The results were recorded and a statistical analysis was undertaken. Then, there were six patients (five male and one female) treated with lift-open laminoplasty on C6, open-door on C3-C5, who suffer from cervical spondylotic myelopathy from December 2020 to January 2021. The average age was 60.3 ± 1.7 years (from 56 to 71 years). Operation time, blood loss, and Japanese Orthopaedic Association (JOA) score recovery rate were recorded. Intraoperative and postoperative complications were observed. RESULTS: The increase of the spinal canal area after open-door laminoplasty measured on postoperative CT images was 123.01 ± 17.06 mm2 and the calculation of the increase of the spinal canal areausing the Pythagorean theorem after open-door laminoplasty was 122.86 ± 15.86 mm2 . A comparison of the actual value with calculative value showed no significant difference (T value = 0.057, P value = 0.955). The calculation of the increase of the spinal canal area after lift-open laminoplasty was 183.57 ± 62.99 mm2 , which was larger than that after open-door laminoplasty (T value = 8.462, P value < 0.001). Mean operation time was 153.3 min and operative blood loss was 600 mL of the six patients treated with lift-open laminoplasty. At 1 month follow-up, all patients had recovered well. JOA score recovery rate was 37.6% and no intraoperative and postoperative complications occurred. CONCLUSION: Lift-open laminoplasty could preserve nearly 100% of extensor muscle, avoid damaging C7 paraspinal muscles and C6-7 posterior muscle-ligament complex, reconstruct the spinous process firmly in the midline, and expand adequate spinal canal area after operation. These advantages could reduce the incidence rate of complications and bring better clinical results than traditional laminoplasty.

Comparison of neck extensor muscle endurance and cervical proprioception between asymptomatic individuals and patients with chronic neck pain.

INTRODUCTION: Neck extensor endurance (NEE) and cervical proprioception are vital for maintaining cervical spine function and defects in these processes have been associated with chronic neck pain (CNP). The objectives of the study are 1) To investigate the association between NEE and cervical joint position error (JPE) in subjects with CNP; 2) to compare the cervical extensor endurance and cervical JPE of CNP subjects with those of asymptomatic controls; and 3) to determine the relationship between Pain Catastrophizing Scale (PCS) scores, NEE, and cervical JPE in subjects with CNP. METHOD: Sixty-four participants (32 asymptomatic, 32 with CNP) participated in this comparative cross-sectional study. Cervical proprioception was assessed by measuring the absolute JPE in the sagittal and transverse directions. NEE was assessed using a clinical extensor endurance test. NEE capacity and JPE were compared and correlated between asymptomatic and CNP subjects. Pain catastrophic behavior was assessed using the Pain Catastrophizing Scale (PCS) in CNP subjects. RESULTS: CNP subjects showed lower NEE capacity (p < 0.001) and significantly larger JPEs (p < 0.001) than asymptomatic participants. NEE negatively correlated with JPEs in all directions (p < 0.001) in asymptomatic subjects and only neck extension errors showed a correlation in CNP subjects (r = -0.45, p = 0.009). PCS scores were negatively correlated with endurance capacity (r = -0.42, p = 0.017) and positively correlated with JPE (flexion: r = 0.57, p = 0.001). CONCLUSION: CNP subjects showed impaired proprioception and lower endurance capacity compared to asymptomatic participants. Neck extension errors alone correlated with JPE in CNP subjects. PCS scores negatively correlated with NEE in subjects with CNP.

The effect of neck muscle fatigue on shoulder humeral rotation joint position sense.

INTRODUCTION: Cervical extensor muscle (CEM) fatigue causes decrements in upper limb proprioceptive accuracy during constrained single-joint tasks. This study used a novel humeral rotation joint position sense (JPS) measurement device to compare JPS accuracy in participants who received acute CEM fatigue vs. non-fatigued controls. METHODS: Participants had vision occluded and were passively guided into postures of internal humeral rotation from a baseline posture before and after a CEM fatigue or control protocol. Mixed model repeated measures ANOVAs were used to verify fatigue and compared absolute, constant, and variable JPS error between groups. RESULTS: CEM fatigue was verified via pre-post reduction in CEM strength, and myoelectric indicators of fatigue. However, between-group comparisons of absolute, constant, and variable JPS error were not statistically significant, despite having large effect sizes. DISCUSSION: Contrary to prevailing literature, unconstrained humeral rotation JPS did not appear to be affected by CEM fatigue in this study. However, between-group differences in JPS error were dwarfed by inter-trial variability, which likely arose due to the unconstrained nature of this task, conflating chances for a Type II error. Future research should perform a kinematic analysis of task constraints to highlight potential compensatory mechanisms obscuring significant findings in this otherwise robust effect.

Weak psoas and spine extensors potentially predispose to hip fracture.

INTRODUCTION: We performed a computed tomography analysis of muscle composition characteristics in hip fracture patients and non-hip fracture controls. METHODS: In total, 43 patients (9 men, 34 women) were included in the hip fracture group, matched 1 to 1 with non-hip fracture controls. Muscle cross-sectional areas were measured in axial CT scan at the body level of the 4th lumbar vertebra (L4), intervertebral disc level between the 5th lumbar vertebra and the 1st sacral vertebra (L5-S1) and just below level of the lesser trochanter (LT). Attenuation was also evaluated through the mean Hounsfield unit (HU) in these areas. RESULTS: The cross-sectional area per weight (CSA/Wt, mm2/kg) of psoas muscle and extensor muscles of the spine showed a significant difference between the 2 groups at both L4 (9.7 vs. 12.4, p < 0.001 and 26.3 vs. 29.2, p = 0.025) and L5-S1 (9.6 vs. 11.5, p = 0.001 and 8.8 vs. 10.3, p = 0.041) levels. In addition, the HU of these muscles differed significantly between the 2 groups at both L4 (33.3 vs. 47.6, p < 0.001 and 13.7 vs. 30.2, p < 0.001) and L5-S1 (39.7 vs. 52.6, p < 0.001 and 3.8 vs. 15.1, p = 0.012) levels. There was no difference in abdominal wall, gluteal, or thigh compartment musculature between the groups. CONCLUSIONS: Poorer quantity and quality of psoas muscle and extensor muscles of the spine rather than whole body muscles may contribute to falls and were characteristic features of the hip fracture patients in this series. These findings should be considered when recommending a preventive exercise and rehabilitation protocol.

Association between Changes in Sagittal X-ray Measurements and Neck Extensor Muscle Atrophy after Cervical Laminoplasty.

BACKGROUND: To investigate the association between neck extensor muscles (NEM) atrophy and changes in the sagittal cervical X-ray measurements after cervical laminoplasty. BASIC PROCEDURES: This retrospective analysis was conducted on 64 patients who underwent cervical laminoplasty from March 2016 to March 2019. The preoperative and postoperative sagittal cervical X-ray images were measured, including the C2-C7 cobb angle, the C2-7 sagittal vertical axis (SVA), and the angle between the plane of the upper endplate of T1 vertebra and the horizontal plane (T1 slope). The preoperative and postoperative steatosis ratios of the NEM were measured using magnetic resonance images. MAIN FINDINGS: There were significant differences between the preoperative and postoperative measurements of the C2-7 cobb angle, the C2-7 SVA, and the T1 slope (P<0.05). The preoperative and postoperative steatosis ratios of each intervertebral level of the NEM also differed significantly (P<0.05). The muscle atrophy ratio at C3/4 was positively correlated with the change in the C2-7 SVA (R=0.646, P<0.001) and negatively correlated with the change in the C2-7 cobb angle (R=-0.445, P<0.001). The muscle atrophy ratio at C7/T1 was positively correlated with the T1 slope (R=0.446, P<0.001). CONCLUSIONS: Muscle atrophy was more severe at the attachment points of the NEM (C3/4, C7T1). There was a significant association between the muscle atrophy ratio and the changes in sagittal cervical X-ray measurements.

Predominant Neck Extensor Muscle Weakness: A Rare Manifestation of Idiopathic Polymyositis.

Dropped head syndrome (DHS) is a rare disease. It can be an isolated phenomenon or secondary to an underlying inflammatory, genetic, or sporadic neuromuscular disease. Idiopathic polymyositis as an underlying cause of DHS is rare and this association has been described very few times in the literature. We describe a case of biopsy-proven polymyositis presenting with predominant neck extensor muscle weakness. This case report goes further into analyzing the biomechanics of neck extension and putative reasons for predilection of the neck extensor muscles with advancing age in patients with DHS who have underlying idiopathic polymyositis.

Effects of sustained unilateral handgrip on corticomotor excitability in both knee extensor muscles.

PURPOSE: Repetitive or sustained simple muscle contractions have been shown to alter corticomotor excitability. The present study investigated the effects of a sustained handgrip contraction with the right hand on motor-evoked potentials (MEPs) in task-unrelated knee extensor muscles and determined whether the effects are influenced by intensity of the handgrip contraction. METHODS: Subjects performed a 120-s sustained handgrip contraction at 10% or 50% maximal voluntary contraction (MVC) using the right hand. MEPs in vastus lateral (VL) muscles elicited by transcranial magnetic stimulation were measured before, during, and after the handgrip contraction. RESULTS: Both the handgrip contractions at 10 and 50% MVC induced significant greater MEPs in the left VL muscle (121.5 ± 25.7%) than in the right VL muscle (97.9 ± 17.4%) from 10 min after the handgrip contraction (P < 0.05). MEPs in both the right and left VL muscles were significantly increased by the handgrip contractions at 10% MVC (124.8 ± 45.2%, P < 0.05), but were not increased by the handgrip contractions at 50% MVC. CONCLUSION: The results of the present study indicate that a unilateral sustained handgrip contraction can differentially alter corticomotor excitability in knee extensor muscles ipsilateral and contralateral to the exercised hand after the handgrip and that the intensity of the handgrip contraction influences corticomotor excitability in both knee extensor muscles after the handgrip.