The latissimus dorsi creates a dynamic track for the inferior angle of the scapula during arm abduction in humans.

BACKGROUND: The importance of several scapulothoracic muscles, including trapezius and serratus anterior, in maintaining physiological scapula kinematics has been highlighted in the past. However, the relationship between the scapula and the latissimus dorsi muscle remains unclear. Our clinical surgical observation is that the latissimus dorsi does not directly attach but rather runs superficial to the inferior angle of the scapula. Based on this observation, we hypothesise that the latissimus dorsi creates a dynamic track on which the scapula glides under the muscle belly during elevation of the arm, creating the latissimus-scapula overlap (LSO). METHODS: All consecutive patients who had a whole-body computed tomography scan (CT) in case of polytrauma evaluation between 2018 and 2021, with complete depiction of the scapula and latissimus dorsi muscle, were analysed. 150 shoulders in 90 patients with arms up were matched according to their age (within five years), gender, and affected side with 150 shoulders in 88 patients with arms down. Patients with pathologies of the upper extremities or thorax that potentially could alter LSO measurements were excluded. LSO was calculated as a ratio of the measured area of the latissimus dorsi projection on the scapula and the total scapula area. RESULTS: The mean age of the 178 patients (48 females; 13 males) was 60 years. The arms-up group showed a significantly higher LSO than the arms-down group (19.9 ± 6.3% vs. 2.7 ± 2.2%; p < 0.0001). In the arms-up group, approximately one fifth of the scapula was overlapped inferiorly by the muscle belly of the latissimus dorsi, contrary to the almost non-existing LSO in the arms-down group. CONCLUSION: With arms up, humans show a significantly higher LSO in comparison to arms down indicating that the latissimus dorsi indeed creates a dynamic track on which the scapula is forced to travel during abduction of the arm. This finding of increased LSO during the elevation of the arm warrants further consideration of the role of the latissimus dorsi in scapula kinematics and potentially scapular dyskinesis. LEVEL OF EVIDENCE: Level two diagnostic study.

Viscoelasticity in trapezius myofascial pain syndrome: quantitative assessment using Real-Time Shear-Wave Elastography.

OBJECTIVE: To investigate the differences in the viscoelastic properties between normal trapezius muscles and those in patients with trapezius myofascial pain syndrome (MPS) using real-time shear-wave elastography (SWE). MATERIALS AND METHODS: This study included 31 patients with trapezius MPS and 31 volunteers. Sixty-one trapezius muscles (41 and 20 on the affected and non-affected side, respectively) of patients with MPS and 62 normal trapezius muscles in volunteers were assessed. Conventional ultrasonic parameters, including skeletal muscle thickness, resistance index (RI), and mean shear wave velocity (SWVmean) of trapezius muscles, were obtained in the seated position with the shoulders and neck relaxed. The daily neck leaning time (unit:hours) of all participants was obtained using a questionnaire. RESULTS: Ultrasound showed no statistically significant differences in thickness or RI of the trapezius muscles of the affected and non-affected sides in MPS patients versus normal trapezius muscles (p = 0.976 and 0.106, respectively). In contrast, the SWVmean of trapezius muscles in patients with MPS was significantly higher than that of normal trapezius muscles in both the affected and non-affected sides (4.41 ± 1.02 m/s vs. 3.35 ± 0.79 m/s, p < 0.001; 4.05 ± 0.63 m/s vs. 3.35 ± 0.79 m/s, p = 0.002). There was no significant difference between the SWVmean of the trapezius muscles on the affected and non-affected sides in patients with MPS (4.41 ± 1.02 m/s vs. 4.05 ± 0.63 m/s, p = 0.225). Correlation analysis showed that daily neck forward time was positively correlated with the SWVmean of the trapezius muscles on the affected and non-affected sides in patients with MPS (r = 0.635, p < 0.001; r = 0.576, p = 0.008). CONCLUSION: SWE can quantitatively evaluate stiffness of trapezius muscles in patients with trapezius MPS. The stiffness of both affected and non-affected trapezius muscles increased in patients with trapezius MPS, and the degree of increase positively correlated with the time of cervical forward leaning.

Ultrasonographic Analysis of Trapezius Muscle for Efficient Botulinum Toxin Type A Injection.

BACKGROUND: Patients nowadays seek medical reduction of the upper trapezius muscle to achieve aesthetic pleasing necklines. Botulinum toxin type A (BoNT-A), a neurotoxin that reduces the force of muscle contraction, is widely used for shoulder contouring. However, detailed metrical data are lacking to guide clinical injection. METHODS: Forty healthy young women were enrolled. All subjects were seated for point marking and measuring of trapezius muscle (TM) anatomical data. At marked locations, the thickness of the subcutaneous tissue, the thickness of the TM, the TM's anterior border, and the depth from the skin surface to the middle of TM were measured using a real-time ultrasound scanner. In addition, photos were taken to assess the shoulder area proportion and shoulder angle. RESULTS: The shoulder area size among participants was 90 ± 15.2 cm2, the average area proportion was 0.55 ± 0.1, and the shoulder angle was 23.12° ± 2.9°. Ultrasonography data reveal that the thickness of the subcutaneous tissue, the thickness of the TM, and the depth from the skin surface to the middle of TM all thickened from the anterior line to the posterior line (P < 0.001). The length of the TM extending forward was 1.47 ± 0.4 cm (range 0.51-1.31 cm). To better evaluate the appearance of the trapezius muscle, we constructed a grading system correlated to shoulder angle. CONCLUSION: In this study, ultrasonography and photos were applied to assess the TM's anatomical features. Trapezius hypertrophy was described on a scale from 0 to 2 based on the shoulder angle. The findings of the present study provide a practical clinical guidance for precise and efficient BoNT-A administration. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Intramuscular Neural Arborization of the Latissimus Dorsi Muscle: Application of Botulinum Neurotoxin Injection in Flap Reconstruction.

Postoperative pain after breast reconstruction surgery with the latissimus dorsi flap is a common occurrence. Botulinum neurotoxin (BoNT) injection during surgery is effective in reducing postoperative pain. This study aimed to determine the most appropriate locations for BoNT injection. A modified Sihler's method was performed on the latissimus dorsi muscles in 16 specimens. Intramuscular nerve arborization was noted under the landmark of the medial side surgical neck of the humerus to the line crossing the spinous process of T5 and the middle of the iliac crest. The latissimus dorsi muscles were divided into medial, middle, and lateral segments with 10 transverse divisions to give 10 sections (each 10%). Intramuscular nerve arborization of the latissimus dorsi muscle was the largest from the medial and lateral part of the muscle ranging from 40 to 60%, middle part from 30 to 60% and medial, middle and lateral part from 70 to 90%. The nerve entry points were at the medial and lateral part with 20-40% regarding the medial side of surgical neck of the humerus to the line crossing spinous process of T5 to the middle of iliac crest. These outcomes propose that an injection of BoNT into the latissimus dorsi muscles should be administered into specific zones.

Sternocleidomastoid size and upper trapezius muscle thickness in congenital torticollis patients: A retrospective observational study.

ABSTRACT: The purpose of this study was to investigate the upper trapezius muscle thickness (UTMT) in congenital muscular torticollis (CMT) patients and determine the correlation among sternocleidomastoid muscle thickness (SCMT), accessory nerve (AN) cross-sectional area (CSA), and UTMT in CMT.This retrospective study consisted of 2 participant groups: Group 1 (SCM mass CMT, n = 20) and Group 2 (Postural CMT, n = 22). For both groups, B-mode ultrasound was performed by a physiatrist to measure the SCMT and UTMT and calculate the CSA of the AN. The correlation among SCMT, CSA of the AN, and UTMT in both groups was evaluated.The between-group comparison revealed that Group 1 had significantly greater SCMT, UTMT, and CSA of the AN on the affected side than Group 2 (P < .05). The intragroup comparison between the affected and unaffected sides also revealed that, in Group 1, the SCMT, UTMT, and CSA of the AN were significantly higher on the affected side than on the unaffected side (P < .05), whereas no significant differences were observed in Group 2. In Group 1, a positive correlation (r = 0.55) was observed between the UTMT and CSA of the AN on the affected side, but not observed between the SCMT and CSA of the AN.The findings of the study indicate that sternocleidomastoid muscle size may impact the thickness of the upper trapezius muscle via the accessory nerve in patients with congenital torticollis.

New application of multimodal ultrasound imaging for identification of myofascial trigger points in the trapezius muscle.

BACKGROUND: The study aimed to quantify the characteristics of trapezius myofascial trigger points (MTrPs) using shear wave elastography (SWE) and contrast-enhanced ultrasound (CEUS) and explore the application value of the new ultrasound techniques in identifying MTrPs. METHODS: Forty patients participated in this study. MTrPs in the trapezius muscle were determined by palpation, and SWE and CEUS were used to quantify the focal and adjacent areas. The elastic modulus values and CEUS parameters between the focal area of MTrPs and adjacent areas were evaluated and compared. Pathological biopsy was performed according to the above two methods, and the pathological tissues were observed by Masson staining, immunohistochemistry and electron microscope. RESULTS: The elastic modulus values were significantly higher for the focal area of MTrPs compared to those for adjacent areas (P<0.05). There were statistically significant differences in MTrP parameters, including peak intensity, mean transit time, and area between the focal and adjacent areas (P<0.05). Masson staining showed that there were inflammatory cell infiltration dominated by lymphocytes in the vascular wall. Electron microscopy showed a large number of fibroblast proliferation, lamellar collagen proliferation and lysosomal deposition; immunohistochemical results: the expression of CD3+, CD4+, CD8+, CD68+, mhc-1+, dys+, CD8 was more than that of CD20 (F=4.385, P=0.036). CONCLUSIONS: Combined use of SWE and CEUS provides a new detection approach for quantitative identification of MTrPs in the trapezius muscle, which has high application value and is a method worthy of wider use in clinical practice.

Ultrasound-guided five-point injection of botulinum toxin for patients with trapezius hypertrophy.

OBJECTIVES: Our study aimed to explore the clinical therapeutic effects of ultrasound-guided five-point injection of botulinum toxin type A for patients with trapezius hypertrophy. METHODS: Twenty female patients diagnosed with trapezius hypertrophy were enrolled in this study. The thicknesses of the trapezius muscle were measured by using the ultrasound scanner to locate the thickest point of trapezius, followed by labelling the other four points around the first point. Botulinum toxin type A was injected bilaterally (50 IU/side, 5 points/side) in the trapezius muscle of these patients. The surgery effects were evaluated by thicknesses of the trapezius muscle, intramuscular needle electromyographic and electroneurographic examinations, appearance changes and patients' satisfactions. RESULTS: Statistically significant differences in thicknesses of the trapezius muscle were observed at 4 weeks (p < 0.001), 12 weeks (p < 0.001), 20 weeks (p < 0.001), 28 weeks (p = 0.011), 36 weeks (p = 0.022), and 44 weeks (p = 0.032) after surgery. The latencies of trapezius muscle became longer at 12 weeks after surgery (left: 2.40 ms, right: 2.53 ms vs. left: 1.75 ms, right: 2.00 ms). Electroneurographic results showed amplitude reduction of compound muscle action potentials (CMAPs) at 12 weeks after surgery (left: 1.91 uV, right: 3.10 uV vs. left: 15.00 uV, right: 15.40 uV). Obvious appearance changes were revealed at 12 weeks after surgery. All of 80% patients were very satisfied, 15% patients were relatively satisfied, and 5% patients were not satisfied with the surgery. CONCLUSION: Ultrasound-guided five-point injection of botulinum toxin type A might be effective for patients with trapezius hypertrophy.

A randomized double blinded placebo controlled study to evaluate motor unit abnormalities after experimentally induced sensitization using capsaicin.

Central sensitization is a condition that represents a cascade of neurological adaptations, resulting in an amplification of nociceptive responses from noxious and non-noxious stimuli. However, whether this abnormality translates into motor output and more specifically, ventral horn abnormalities, needs to be further explored. Twenty healthy participants aged 20-70 were randomly allocated to topical capsaicin or a placebo topical cream which was applied onto their left upper back to induce a transient state of sensitization. Visual analogue scale (VAS) ratings of pain intensity and brush allodynia score (BAS) were used to determine the presence of pain and secondary allodynia. Surface electromyography (sEMG) and intramuscular electromyography (iEMG) were used to record motor unit activity from the upper trapezius and infraspinatus muscles before and twenty minutes after application of capsaicin/placebo. Motor unit recruitment and variability were analyzed in the sEMG and iEMG, respectively. An independent t-test and Kruskal-Wallis H test were performed on the data. The sEMG results demonstrated a shift in the motor unit recruitment pattern in the upper trapezius muscle, while the iEMG showed a change in motor unit variability after application of capsaicin. These results suggest that capsaicin-induced central sensitization may cause changes in ventral horn excitability outside of the targeted spinal cord segment, affecting efferent pathway outputs. This preclinical evidence may provide some explanation for the influence of central sensitization on changes in movement patterns that occur in patients who have pain encouraging of further clinical investigation.Clinical Trials registration number: NCT04361149; date of registration: 24-Apr-2020.

Latissimus Dorsi flap enhancement by lipofilling as an immediate breast reconstruction technique for skin-preserving mastectomy.

AIM: To evaluate Latissimus Dorsi flap (LD) enhancement by lipofilling as an immediate breast reconstruction technique, for skin-preserving mastectomy regarding oncological safety, fat graft resorption after radiotherapy, and patients' satisfaction. PATIENTS AND METHODS: This is a prospective study that included female patients complaining of breast cancer. Patients were subjected to skin-preserving mastectomy associated with Latissimus Dorsi flap enhancement by lipofilling using the multisite, and multilayer fat grafting technique of injection. Patients were followed up for early and late postoperative complications including recurrence. Volumetric CT was performed before and after the radiotherapy to detect the percentage of fat resorption. Postoperative patients' satisfaction was assessed using the Kyungpook National University Hospital (KNUH) Breast Reconstruction Satisfaction Questionnaire. RESULTS: The study included 25 female patients with a mean age of 36.48 ± 5.87 years. The mean period of follow-up was 30.32 ± 5.82 months. Local recurrence was encountered in 1 patient (4%). The mean volume reduction of the injected fat graft was 27.36 ± 8.58%. Twenty-three patients (92%) declared their satisfaction after the operation, one of them was satisfied only after she underwent a second session of lipofilling. CONCLUSIONS: Skin-preserving mastectomy with the enhancement of the LD by lipofilling for immediate reconstruction of the breast seems to be a safe and simple technique for the achievement of autologous breast reconstruction. It has an acceptance rate of locoregional recurrence and minor postoperative complications. The procedure showed high postoperative patients' satisfaction and a reasonable percentage of fat resorption as confirmed by volumetric CT imaging techniques.

Machine Learning Diagnostic Modeling for Classifying Fibromyalgia Using B-mode Ultrasound Images.

Fibromyalgia (FM) diagnosis remains a challenge for clinicians due to a lack of objective diagnostic tools. One proposed solution is the use of quantitative ultrasound (US) techniques, such as image texture analysis, which has demonstrated discriminatory capabilities with other chronic pain conditions. From this, we propose the use of image texture variables to construct and compare two machine learning models (support vector machine [SVM] and logistic regression) for differentiating between the trapezius muscle in healthy and FM patients. US videos of the right and left trapezius muscle were acquired from healthy (n = 51) participants and those with FM (n = 57). The videos were converted into 64,800 skeletal muscle regions of interest (ROIs) using MATLAB. The ROIs were filtered by an algorithm using the complex wavelet structural similarity index (CW-SSIM), which removed ROIs that were similar. Thirty-one texture variables were extracted from the ROIs, which were then used in nested cross-validation to construct SVM and elastic net regularized logistic regression models. The generalized performance accuracy of both models was estimated and confirmed with a final validation on a holdout test set. The predicted generalized performance accuracy of the SVM and logistic regression models was computed to be 83.9 ± 2.6% and 65.8 ± 1.7%, respectively. The models achieved accuracies of 84.1%, and 66.0% on the final holdout test set, validating performance estimates. Although both machine learning models differentiate between healthy trapezius muscle and that of patients with FM, only the SVM model demonstrated clinically relevant performance levels.

High Clinical Failure Rate After Latissimus Dorsi Transfer for Revision Massive Rotator Cuff Tears.

PURPOSE: To evaluate the clinical success rate, along with risk factors for failure, in patients undergoing latissimus dorsi transfer for the treatment of massive, irreparable, previously failed rotator cuff tears. METHODS: We performed a retrospective chart review of prospectively collected data from an institutional shoulder outcome registry. All patients who underwent latissimus dorsi transfer for previously failed rotator cuff repair between 2006 and 2013 with a minimum follow-up period of 1 year were included in the study. The indications for inclusion were large (≥2 tendons), retracted, chronic rotator cuff tears with fatty infiltration or atrophy for which prior surgical repair had failed. Preoperative and postoperative American Shoulder and Elbow Surgeons (ASES) and Simple Shoulder Test scores were collected, along with postoperative Single Assessment Numerical Evaluation scores. Complications and clinical failures (Δ in ASES score <17) were recorded. Patient demographic and tear characteristics were evaluated as potential risk factors for failure. RESULTS: A total of 22 patients (mean age, 53 ± 6 years) were included in the study, with a mean follow-up time of 3.4 ± 1.1 years. Over 63% of patients (n = 14) reported undergoing 2 or more prior failed rotator cuff repairs. Patients undergoing latissimus dorsi transfer showed significant improvements in ASES scores (from 35.2 ± 21.9 preoperatively to 55.8 ± 22.9 postoperatively, P = .001), Simple Shoulder Test scores (from 3.5 ± 3.1 preoperatively to 5.2 ± 3.4 postoperatively, P = .002), and pain scores (from 5.9 ± 2.8 preoperatively to 4.6 ± 4.3 postoperatively, P = .002) at final follow-up. The complication rate after latissimus transfer was 27%. The rate of revision to reverse total shoulder arthroplasty was 13.6% (n = 3) after a mean of 2.7 years, and the clinical failure rate was 41% (n = 9) at final follow-up. An acromiohumeral interval of less than 7 mm (P = .04) and high-grade fatty infiltration (grade 3 or greater, P = .004) were significant preoperative risk factors for clinical failure. CONCLUSIONS: Latissimus dorsi tendon transfer resulted in a clinical failure rate of 41% and complication rate of 27%, with an acromiohumeral interval of less than 7 mm and high-grade fatty infiltration being associated with postoperative failure. LEVEL OF EVIDENCE: Level IV.

CT-Derived Pretreatment Thoracic Sarcopenia Is Associated with Late Mortality after Thoracic Endovascular Aortic Repair.

BACKGROUND: Frailty, characterized by physiologic depletion, predicts postoperative morbidity and mortality in vascular surgery patients. CT-derived sarcopenia is a valuable method for objectively staging frailty preoperatively. PURPOSE: With prior analyses primarily measuring psoas cross-sectional area on CT, we compared a method of measuring thoracic sarcopenia to existing techniques of lumbar sarcopenia and assessed the association with long-term survival and outcomes post-Thoracic Endovascular Aortic Repair (TEVAR). METHODS: Prospectively collected data of 217 patients undergoing TEVAR from 2009 to 2012 were reviewed. Thoracic sarcopenia was quantified by measuring total area of the rectus abdominis, latissimus dorsi, intercostal, erector spinae, and external and internal oblique muscles at the T12 vertebral level. Total psoas area at the L3 was used to measure lumbar sarcopenia. RESULTS: 200 patients had preoperative imaging enabling measurements of thoracic sarcopenia, 186 of these patients were also assessed for lumbar sarcopenia. Thoracic sarcopenic patients were older, had lower body mass indices, were more commonly female, and most commonly being treated for aneurysms. Thoracic sarcopenic patients had significantly higher rates of congestive heart failure, hypertension, prior vascular intervention, and TEVAR-related adverse events. Thoracic sarcopenia was associated with significantly higher mortality at 2 and 5 years post-TEVAR (2-year mortality: 19% vs 8%, P = 0.02; 5-year mortality: 31% vs 18%, P = 0.03). Lumbar sarcopenia was not associated with increased mortality at any time point. Patients whose muscle mass degraded over 48-month follow-up did not experience significantly higher rates of adverse events. CONCLUSIONS: CT-derived thoracic sarcopenia, but not lumbar sarcopenia, is significantly associated with 5-year mortality post-TEVAR.

Rhomboid Intercostal and Subserratus Plane Block: A Cadaveric and Clinical Evaluation.

BACKGROUND AND OBJECTIVES: Fascial plane blocks are rapidly emerging to provide safe, feasible alternatives to epidural analgesia for thoracic and abdominal pain. We define a new option for chest wall and upper abdominal analgesia, termed the rhomboid intercostal and subserratus plane (RISS) block. The RISS tissue plane extends deep to the erector spinae muscle medially and deep to the serratus anterior muscle laterally. We describe a 2-part proof-of-concept study to validate the RISS block, including a cadaveric study to evaluate injectate spread and a retrospective case series to assess dermatomal coverage and analgesic efficacy. METHODS: For the cadaveric portion of the study, bilateral ultrasound-guided RISS blocks were performed on 6 fresh cadavers with 30 mL of 0.5% methylcellulose with india ink. For the retrospective case series, we present 15 patients who underwent RISS block or RISS catheter insertion for heterogeneous indications including abdominal surgery, rib fractures, chest tube-associated pain, or postoperative incisional chest wall pain. RESULTS: In the cadaveric specimens, we identified staining of the lateral branches of the intercostal nerves from T3 to T9 reaching the posterior primary rami deep to the erector spinae muscle medially. In the clinical case series, dermatomal coverage was observed in the anterior hemithorax with visual analog pain scores less than 5 in patients who underwent both single-shot and continuous catheter infusions. CONCLUSIONS: Our preliminary cadaveric and clinical data suggest that RISS block anesthetizes the lateral cutaneous branches of the thoracic intercostal nerves and can be used in multiple clinical settings for chest wall and upper abdominal analgesia.

Quantitative Ultrasound Using Texture Analysis of Myofascial Pain Syndrome in the Trapezius.

Objective-The objective of this study is to assess the discriminative ability of textural analyses to assist in the differentiation of the myofascial trigger point (MTrP) region from normal regions of skeletal muscle. Also, to measure the ability to reliably differentiate between three clinically relevant groups: healthy asymptomatic, latent MTrPs, and active MTrP. Methods-18 and 19 patients were identified with having active and latent MTrPs in the trapezius muscle, respectively. We included 24 healthy volunteers. Images were obtained by research personnel, who were blinded with respect to the clinical status of the study participant. Histograms provided first-order parameters associated with image grayscale. Haralick, Galloway, and histogram-related features were used in texture analysis. Blob analysis was conducted on the regions of interest (ROIs). Principal component analysis (PCA) was performed followed by multivariate analysis of variance (MANOVA) to determine the statistical significance of the features. Results-92 texture features were analyzed for factorability using Bartlett's test of sphericity, which was significant. The Kaiser-Meyer-Olkin measure of sampling adequacy was 0.94. PCA demonstrated rotated eigenvalues of the first eight components (each comprised of multiple texture features) explained 94.92% of the cumulative variance in the ultrasound image characteristics. The 24 features identified by PCA were included in the MANOVA as dependent variables, and the presence of a latent or active MTrP or healthy muscle were independent variables. Conclusion-Texture analysis techniques can discriminate between the three clinically relevant groups.

Thoracic paravertebral block versus thoracic epidural analgesia for post-operative pain control in open pancreatic surgery: A randomized controlled trial.

STUDY OBJECTIVE: The purpose of this study was to compare the efficacy of bilateral ultrasound guided thoracic paravertebral catheters to a thoracic epidural after open pancreatic surgery. DESIGN: This was a prospective non-blinded randomized controlled trial. SETTING: Academic hospital operating room, postoperative recovery area, and ward. PATIENTS: 53 patients aged 18 and above who had open pancreatic surgery. INTERVENTIONS: Patients received either bilateral thoracic paravertebral block at T8 with an infusion of 0.2% ropivacaine or thoracic epidural analgesia at T7/8 with an infusion of 0.125% bupivacaine with hydromorphone 6 µg/mL. MEASUREMENTS: Pain scores, opioid use, length of recovery room and hospital stay, adverse events, and incidence of nausea and vomiting. MAIN RESULTS: There was no difference in baseline demographics between the two groups. There were no significant differences in pain scores between the two groups in each of the first five days after surgery. There was no difference in length of stay nor nausea and vomiting. There was significantly less modality related adverse events in the paravertebral group compared to the epidural group (p = 0.02). CONCLUSIONS: The use of thoracic paravertebral catheters provided comparable analgesia and less modality related adverse events when compared to a thoracic epidural in patients undergoing open pancreaticoduodenectomy.