Effects of different modalities of afferent stimuli of the lumbo-sacral area on control of lumbar paravertebral muscles

Somatosensory feedback to the central nervous system is essential to plan, perform and refine spine motor control. However, the influence of somatosensory afferent input from the trunk on the motor output to trunk muscles has received little attention. The objective was to compare the effects of distinct modalities of afferent stimulation on the net motoneuron and corticomotor excitability of paravertebral muscles. Fourteen individuals were recruited. Modulation of corticospinal excitability (motor-evoked potential [MEP]) of paravertebral muscles was measured when afferent stimuli (cutaneous noxious and non-noxious, muscle contraction) were delivered to the trunk at 10 intervals prior to transcranial magnetic stimulation. Each peripheral stimulation was applied alone, and subsequent EMG modulation was measured to control for net motoneuron excitability. MEP modulation and MEP/EMG ratio were used as measures of corticospinal excitability with and without control of net motoneuron excitability, respectively. MEP and EMG modulation were smaller after evoked muscle contraction than after cutaneous noxious and non-noxious stimuli. MEP/EMG ratio was not different between stimulation types. Both MEP and EMG amplitudes were reduced after evoked muscle contraction, but not when expressed as MEP/EMG ratio. Noxious and non-noxious stimulation had limited impact on all variables. Distinct modalities of peripheral afferent stimulation of the lumbo-sacral area differently modulated responses of paravertebral muscles, but without an influence on corticospinal excitability with control of net motoneuron excitability. Muscle stimulation reduced paravertebral activity and was best explained by spinal mechanisms. The impact of afferent stimulation on back muscles differs from the effects reported for limb muscles.

Effect of preoperative erector spinae muscles mass on postoperative outcomes in patients with left ventricular assist devices

BACKGROUND

Frailty influences the postoperative outcomes in patients undergoing left ventricular assist device (LVAD) implantation. Recently, erector spinae muscle (ESM) mass has been proposed as a parameter to assess frailty accurately. Thus, the purpose of the present study was to evaluate whether preoperative ESM mass is associated with short- and long-term clinical outcomes in patients with LVAD.

METHODS

A total of 119 consecutive patients with LVAD were enrolled between January 2010 and October 2017 at a single heart center. The ESM area, ESM index, and Hounsfield units (HU) of the ESM were calculated by computed tomography for preoperative ESM mass evaluation. We then statistically evaluated the in-hospital mortality, major adverse cardiovascular events (MACE), duration of hospital stay, and long-term survival.

RESULTS

In a multivariate Cox regression analysis, ESM mass indicated no effect on all clinical outcomes. In addition, the ESM area presented a weak but significant negative linear correlation only with the duration of hospital stay (r = -0.21, p < .05). In contrast, the Model For End-stage Liver Disease (MELD) score and preoperative venous-arterial extracorporeal membrane oxygenation (va-ECMO) were significant predictive factors for in-hospital mortality (MELD score: p < .001, hazard ratio [HR] 1.1; preoperative va-ECMO: p < .01, HR 2.72) and MACE (MELD score: p < .001, HR 1.07; preoperative va-ECMO: p < .005, HR 2.62).

CONCLUSION

Preoperative ESM mass might predict the length of hospital stay in patients undergoing LVAD implantation. In contrast, it had no effect on MACE, in-hospital mortality, or long-term survival in this study.

Prognostic implication of erector spinae muscles in non-small-cell lung cancer patients treated with immuno-oncology combinatorial chemotherapy

Background

The quantity of skeletal muscles has recently been reported to have prognostic value in patients with non‐small‐cell lung cancer (NSCLC) treated with second‐line immunotherapy. However, the prognostic role of skeletal muscle assessment in NSCLC patients undergoing first‐line immuno‐oncology (IO) combinatorial treatment (IO‐chemotherapy) has not been elucidated.

Methods

We retrospectively reviewed 36 patients with NSCLC undergoing first‐line IO‐chemotherapy between April 2018 and June 2021 in our hospital. The cross‐sectional area of the erector spinae muscle (ESM_CSA) was evaluated by manual tracing on computed tomography scans at the level of the 12th thoracic vertebra before initiating IO‐chemotherapy. To minimize deviation due to physique, the ESM_CSA was adjusted by body surface area (BSA) (ESM_CSA to BSA ratio: ESM_CSA/BSA). A survival time analysis was performed using the Kaplan–Meier method and log‐rank test. A multivariate analysis with Cox proportional hazards model was conducted to investigate the prognostic value of the ESM_CSA/BSA and inflammatory and nutritional indices.

Results

The median progression‐free survival (PFS) and overall survival (OS) were 6.5 and 16.6 months, respectively. Intergroup comparison by the log‐rank test revealed that there was no significant difference in the median PFS, but the median OS was significantly long in the high ESM_CSA/BSA (>19 cm^2/m²) (high ESM_CSA/BSA group, p = 0.0373). The multivariate analysis showed that ESM_CSA/BSA was an independent prognostic factor for OS (hazard ratio 0.79, p = 0.044).

Conclusions

The results of this study indicate that the pretreatment ESM_CSA/BSA may be a potential prognostic factor in NSCLC patients receiving first‐line IO‐chemotherapy.

Trunk Muscle Cross-Sectional Area as a Predictive Factor for Length of Postoperative Hospitalization after Surgical Aortic Valve Replacement

Purpose: We investigated the utility of trunk muscle cross-sectional area to predict length of hospitalization after surgical aortic valve replacement (AVR) for aortic stenosis (AS).

Methods: Adult AS patients who underwent isolated AVR at a single institution were studied. The cross-sectional area of the erector spinae muscles (ESM) at the first and second lumbar vertebrae and that of the psoas muscle (PM) at the third and fourth lumbar vertebrae were measured on preoperative computed tomography (CT). Each was indexed to body surface area. Risk factors for prolonged postoperative hospitalization (>3 weeks) were assessed using multivariate regression analyses.

Results: Of 56 patients (mean age 76 ± 9 years; 25 men), 20 (35.7%) patients required prolonged hospitalization. A smaller indexed ESM cross-sectional area at the first lumbar vertebra (per 1 cm/m², odds ratio [OR] = 0.71, 95% confidence interval [CI] = 0.57–0.88, P <0.01) and lower preoperative serum albumin level (per 0.1 g/dL, OR = 0.83, 95% CI = 0.70–0.99, P <0.05) were shown as independent predictors. Indexed PM cross- sectional area was not statistically significant.

Conclusion: The cross-sectional area of the trunk muscles can be used to identify patients at risk for prolonged hospitalization after AVR for adult AS.

Determination of the motor unit behavior of lumbar erector spinae muscles through surface EMG decomposition technology in healthy female subjects

INTRODUCTION

The aims of this study were to determine the motor unit behavior of the erector spinae muscles and to assess whether differences exist between the dominant/nondominant sides of the back muscles.

METHODS

Nine healthy women, aged 21.7 years (SD = 0.7), performed a back extension test. Surface electromyographic decomposition data were collected from both sides of the erector spinae and decomposed into individual motor unit action potential trains. The mean firing rate for each motor unit was calculated, and a regression analysis was performed against the corresponding recruitment thresholds.

RESULTS

The mean firing rate ranged from 15.9 to 23.9 pps and 15.8 to 20.6 pps on the dominant and nondominant sides, respectively. However, the early motor unit potentials of the nondominant lumbar erector spinae muscles were recruited at a lower firing rate.

CONCLUSIONS

This technique may further our understanding of individuals with back pain and other underlying neuromuscular diseases. Muscle Nerve 55: 28-34, 2017.

Muscle fibre size and type distribution in thoracic and lumbar regions of erector spinae in healthy subjects without low back pain: normal values and sex differences

This study sought to investigate the normal muscle fibre size and type distribution of the human erector spinae, both in thoracic and lumbar regions, in a group of 31 young healthy male (n = 17) and female (n = 14) volunteers. Two percutaneous muscle biopsy samples were obtained under local anaesthesia, from the belly of the left erector spinae, at the levels of the 10th thoracic and 3rd lumbar vertebrae. Samples were prepared for routine histochemistry for the identification of fibre types. Fibre size (cross-sectional area (CSA) and narrow diameter (ND)) was quantified using computerised image analysis. The mean CSA/ND for each fibre type was greater in the thoracic than the lumbar region, but there was no difference between the 2 regions either for percentage type I (i.e. percentage distribution by number), percentage type I area (i.e. relative area of the muscle occupied by type I fibres) or the ratio describing the size of the type I fibre relative to that of the type II. Men had larger fibres than women, for each fibre type and at both sampling sites. In the men, each fibre type was of a similar mean size, whereas in the women the type I fibres were considerably larger than both the type IIA and type IIB fibres, with no difference between the latter two. In both regions of the erector spinae there was no difference between men and women for the proportion (%) of a given fibre type, but the percentage type I fibre area was significantly higher in the women. The erector spinae display muscle fibre characteristics which are clearly very different from those of other skeletal muscles, and which, with their predominance of relatively large type I (slow twitch) fibres, befit their function as postural muscles. Differences between thoracic and lumbar fascicles of the muscle, and between the muscles of men and women, may reflect adaptive responses to differences in function. In assessing the degree of any pathological change in the muscle of patients with low back pain, it seems clear that (1) sex cannot be disregarded and (2) 'atrophied' (using the criteria from other muscles) type II fibres are not necessarily abnormal for the erector spinae, particularly in women.