Scalene Research Articles

The course of the phrenic nerve in the neck region and its relationship with adjacent anatomical structures in the thoracic inlet.

This study aims to reveal the relationship of the phrenic nerve (PhN) with its neighboring structures in the lower neck region more comprehensively than previous studies and to minimize nerve damage by enabling invasive procedures in this region to be performed with high accuracy. Forty-one heminecks were evaluated. The relationship between the PhN and the anterior scalene muscle (ASM), internal thoracic artery (ITA), branches of subclavian artery (SA) and subclavian vein (SV) was examined. It was observed that the PhN was located medial to the ASM in all cases. The distances were higher in male cadavers. The PhN was found to enter the thorax lateral to the ITA in 15/41 and medial to it in 25/41 sides. In 17/41 cases, the closest SA branch to the PhN was the thyrocervical trunk (TT) and in 24 cases the ITA. The PhN was located behind the SV in 38 cases and in front of it in 2 cases.The accessory PhN was found in 4/41 sides. There was no significant difference in morphometric findings between genders (p > 0.05). However, significant differences were observed between the parameters (p < 0.05). The anatomy and variations of the PhN are of great importance in surgical interventions and invasive procedures in the neck region. The study provides important information to reduce the risk of damage to the PhN in surgical procedures. In addition, knowledge of the anatomical variations of the nerve may contribute to more successful results in nerve grafting and other surgical applications.

Anatomic Study and Clinical Application of C7 Nerve Transfer Surgery via the Anterior Vertebral Approach for Central Upper Limb Spastic Paralysis

Objective: To explore the anatomic characteristics of C7 nerve localization, course, and length during cross-transfer surgery of the C7 nerve through the anterior vertebral approach and investigate the feasibility, safety, and clinical efficacy of C7 nerve transfer surgery through the anterior vertebral approach for the treatment of central upper limb spastic paralysis. Methods: Four fresh-frozen adult head and neck samples were selected. C7 nerve transfer surgery was simulated through the anterior vertebral approach. The vertical distance between the C7 nerve and the medial edge of the clavicle, the length of the C7 nerve, and the shortest distance of C7 nerve transfer required through the anterior vertebral approach were measured. This was a retrospective analysis of the clinical data of 2 patients with central upper limb spastic paralysis after C7 nerve transfer surgery at Northern Jiangsu People’s Hospital affiliated with Yangzhou University. The patients were all female, aged 50 to 51 years, with upper limb paralysis on the affected side. The muscle strength was grade 0 or grade 1, and the muscle tension was relatively high. Both patients underwent C7 nerve transfer surgery through the anterior vertebral approach. Upper limb sensation and motor function were observed. Results: Bilateral C7 nerves can be fully exposed and located through the anterior vertebral approach. The C7 nerve runs between the anterior and middle scalene muscles, with a vertical distance of 1.7 to 2.5 (2.1±0.3) cm from the inner edge of the clavicle. The length of the C7 nerve is 5.6 to 6.8 (6.4±0.5) cm, and the shortest distance of C7 nerve transfer through the anterior vertebral approach is 4.8 to 5.7 (5.3±0.4 cm). Two patients with central upper limb paralysis successfully underwent C7 nerve transfer surgery using the anterior vertebral approach. Two patients had normal motor function in the healthy upper limb after surgery but experienced pain and numbness in the healthy upper limb. Both patients recovered within 1 month. Two patients experienced significant relief of spasticity symptoms in the affected upper limb. One patient was followed up for 15 months, and, at the last follow-up, sensation in the affected upper limb was normal, with proximal muscle strength at level 3 and distal muscle strength at level 2. Another patient was followed up for 11 months, and at the last follow-up, sensation in the affected upper limb was normal, with proximal muscle strength at level 1+ and distal muscle strength at level 1. Conclusion: For central upper limb spastic paralysis, C7 nerve transfer surgery through the anterior vertebral approach is safe and feasible and is a good treatment option. Related anatomic research can effectively guide clinical surgery and assist in locating the C7 nerve, and incising the musculus longus colli can shorten the distance of C7 nerve transfer.

Relationship Between Posterior Tibial Artery Blood Flow And Lower Leg Flexibility Among Collegiate Runners

Purpose: Understanding relationships between blood flow and muscle inflexibility in the lower leg can support improved healthcare competency. Sports medicine practitioners might use the reference ranges and knowledge of relationships among these variables to support effective health screenings among their competitive runners. These variables have been linked in other areas of the body where inflexibility in the pectoralis minor and scalene muscles have been associated with diminished blood flow to the upper limb. No studies, however, have examined the relationship between vascular and mobility characteristics in the lower legs of runners. Therefore, the purpose of this study was to examine the relationship between blood flow in the posterior tibial artery and ankle range of motion (ROM) among competitive runners. Methods: Blood flow in the posterior tibial artery and ankle ROM were measured bilaterally on twenty-five, asymptomatic collegiate track athletes (15 males, 10 females, age = 20.0±1.2 years, height = 171.5±10.2 cm, mass = 66.7±13.7 kg) using diagnostic ultrasound and standard goniometry, respectively. Pearson correlation analysis was used to analyze the relationship between blood flow in the posterior tibial artery and ROM of the ankle joint. Results: Findings revealed no significant relationship between blood flow in the dominant leg’s posterior tibial artery and dorsiflexion (r=.14, P=.52, CI95% = -0.27 – 0.51) or plantarflexion (r=-.32, P=.12, CI95% = -0.63 – 0.09) and no significant relationship between blood flow in the non-dominant leg’s posterior tibial artery and dorsiflexion (r=-.02, P=.93; CI95% = -0.41 – 0.38) or plantarflexion (r=-.02, P=.92; CI95% = -0.41 – 0.38). Conclusion: While muscle inflexibility is associated with compromised blood flow in other body regions, findings of this study demonstrated no relationship between the variables within the lower legs of a sample of competitive runners. Sports medicine practitioners should consider these findings in their efforts to predict, prevent, and manage potential vascular and musculoskeletal adaptations among clients/patients who are competitive runners.

Association of Concave Deformity of the Anterior Scalene on Magnetic Resonance Imaging with Vascular Variant of Neurogenic Thoracic Outlet Syndrome.

Neurogenic thoracic outlet syndrome (NTOS) is a dynamic compression of the brachial plexus. This study aimed to evaluate the correlation between the concave deformity of the posterior edge of the anterior scalene muscle (CDAS) on sagittal T1 with intraoperative findings of vascular compression. The second aim was to define the NTOS vascular subtypes and establish possible treatments. We retrospectively reviewed patients who met the Consortium for Research and Education on Thoracic Outlet Syndrome criteria for NTOS and were operated on after a failed rehabilitation program. Forty-four patients were included; mean age was 29.51 years (range: 13-55 years), and 24 (54.5%) were women. CDAS on sagittal T1 magnetic resonance imaging (MRI) was identified in 20 of 44. Patients were divided into two categories: type A (pure NTOS) (20 of 44); and type B (mixed neurogenic-vascular variants) (24 of 44). Type B was divided into B1, B2, and B3, corresponding to subclavian artery (SCA) compression (seven of 44), subclavian vein compression (SCV) (five of 44), and both SCA and SCV compression (12 of 44), respectively. All patients with B1 had CDAS on MRI T1 sagittal, whereas CDAS was found on 5%, 60%, and 58.3% in types A, B2, and B3, respectively. Intraoperatively, all patients had at least one structural anomaly. Preoperative symptoms of lower or middle-lower brachial plexus trunk compressions were more prominent in patients with the vascular variant (B1: 85%, B2: 83%, and B3: 83%) than the pure NTOS (type A) (40%). NTOS presents as four subtypes: pure neurogenic (A) and vascular (B1, B2, and B3). Preoperative middle/lower trunk symptoms combined with positive upper limb duplex ultrasound of the SCA, SCV, and sagittal MRI show that a CDAS is correlated with the vascular form of NTOS and predicts failure of preoperative rehabilitation program.

Revisiting the anatomy of the pectoral nerves and nerve loops of the brachial plexus in the goat (Capra hircus)

BackgroundThe anatomy of the pectoral nerves and the two nerve loops on the course of the axillary artery was revisited to complement current general descriptions as well as to argue whether the nerves contributing to the formation of the pectoral loop are the cranial pectoral nerves. Besides, the positional relationship between the scalene muscles and the nerve roots of the brachial plexus, which contribute to the nerves aimed in this study, was also examined at the same time as the dissection. MethodsTwenty brachial plexuses of 10 domestic adult goats (8 females and 2 males) were examined using gross dissection in this study. ResultsIn many dissections (95 %), the last bundle of scalenus ventralis muscle was found to pass between the roots of C7 and C8, dividing the brachial plexus into the cranial (ventral) and caudal (dorsal) parts. Two pectoral nerves were noted to contribute to the formation of the first nerve loop around the axillary artery. The first pectoral nerve arose predominantly from the ventral branches of C6 and C7 in company with the n. musculocutaneus, while the second pectoral nerve arose directly from C8 in 70 % of the dissections or as the first branch of the n. thoracicus lateralis (C8, T1) in the remaining 30 %. After the nerve loop, the second pectoral nerve branched off to innervate the superficial surface of the m. pectoralis profundus toward its insertion. The m. subclavius was found to receive its innervation from several sources, including the ventral branches of the brachial plexus. Interestingly, in 4 of the 14 dissections a communication between the n. subclavius and the n. phrenicus heretofore not found in the animal anatomy literature was found. In 16 of the 20 dissections (60 %), the ramus muscularis proximalis of the n. musculocutaneus received the communicating branch(s) from the n. medianus at the site of the second nerve loop, ansa axillaris. ConclusionThe second pectoral nerve contributing to the pectoral loop would be better described as the caudal pectoral nerve rather than the cranial pectoral nerve. Besides the evolutionary perspectives, understanding the findings of this study would be helpful for teaching veterinary anatomy.

Benefits of chest wall mobilization on respiratory efficiency and functional exercise capacity in people with severe chronic obstructive pulmonary disease (COPD): A randomized controlled trial.

Coexistence of chest wall hypomobility and lung hyperinflation compromises respiratory muscle function and respiratory efficiency in people with severe chronic obstructive pulmonary disease (COPD). This study aimed to investigate the effect of chest wall mobilization on functional exercise capacity, respiratory muscle activity and respiratory muscle tissue oxygen saturation for people with severe COPD. Thirty male adults (age: 75 ± 6) diagnosed with severe COPD completed a 6-week programme (twice/week) according to intervention randomization (chest wall mobilization group, CWMG, n = 15; control group, CG, n = 15). Both groups received standardized education and walking exercise, while CWMG also received chest wall and thoracic spine mobilization. Electromyography of the essential and accessory respiratory muscles and tissue oxygen saturation of the intercostal muscle (StO2, measured by near-infrared spectroscopy) during incremental cycle exercise test were measured and compared between the two groups at pre-programme, post-programme and 3-month follow-up. Patients in CWMG demonstrated a significant increase in exercise tolerance from <3 METS to 4-6 METS (p = 0.000) after intervention. A significant decrease in activity of scalene, sternocleidomastoids and intercostal muscle during exercise test (p < 0.01) was found in CWMG, as compared to CG. A significant decrease in StO2 (p < 0.05) and greater decline in the slope of oxygenation dissociation (p = 0.000) were seen in CWMG during exercise test. These positive results were maintained at 3-month follow-up in CWMG. Improvements in exercise tolerance, respiratory muscle efficiency and oxygenation extraction ability in CWMG suggest a potential clinical benefit of integrating chest wall and thoracic spine mobilization for rehabilitation of people with severe COPD.

An unreported accessory muscle on the neck region

Anatomical variations or accessory muscles on the neck region are important for clinicians and surgeons. This case report aims to contribute to the literature by demonstrating the presence of a previously unrecognized muscle on the lateral neck region. During routine gross anatomy dissection of a 59-year-old male cadaver; an unreported muscle was observed next to the scalene muscles on the left lateral neck region. The distance between the center of the scalenus medius and the insertion of the muscle was 6.17 cm, and the distance between the scapular notch and the insertion of the muscle was 1.56 cm. The distance between the aponeurosis that connects the superior and the inferior bellies of the omohyoideus muscle and the first head of the muscle was 6.24 cm. This anatomical formation, which is not included in the literature, has anatomical and clinical importance in controversial clinical cases in neck pathologies.

Prevalence of Myofascial Trigger Points in Isolated Idiopathic Cervical Dystonia: A Possible Contributor to Pain, Movement and Disability.

Myofascial trigger points (TrPs) are hypersensitive points located in a tight band of muscle that, when palpated, produce not only local pain but also referred (distant) pain. The role of TrPs in patients with cervical dystonia (CD) has not been investigated. To identify the presence of TrPs in patients with isolated idiopathic CD and their association with pain. Thirty-one patients (74.2% women; age: 61.2 years, SD: 10.1 years) participated. TrPs were explored in the sternocleidomastoid, upper trapezius, splenius capitis, levator scapulae, anterior scalene, suboccipital, and infraspinatus muscles. Clinical features of CD were documented as well as the presence of pain. The severity of dystonia and its consequences were assessed using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). The mean number of TrPs for each patient was 12 (SD:3), with no differences between patients with pain (n = 20) and those without pain (n = 11). Active TrPs were only found in patients with pain (mean: 7.5, SD:4). Latent TrPs were found in both groups but were more prevalent (P < 0.001) in patients without pain (mean: 11, SD:3.5) than in those with pain (mean: 5, SD:3.5). The number of active TrPs or latent TrPs was positively associated with the TWSTRS disability subscale and the TWSTRS total score. The number of active, but not latent, TrPs was associated with worse scores on the TWSTRS pain subscale. Active TrPs were present in patients with CD reporting pain, while latent TrPs were present in all CD patients, irrespective of their pain status. The numbers of active/latent TrPs were associated with disability. TrPs could act as pain generators in CD and also contribute to the involuntary muscle contractions characteristic of dystonia.

Reliability of digital filtering on surface electromyographic activity of respiratory muscles in patients with COVID-19

Introduction: Surface electromyography (sEMG) is valuable for assessing respiratory muscle activity, but the influence of electromagnetic fields can impair the accuracy of the signals. This study aims to compare the Root Mean Square (RMS) values of sEMG signals from respiratory muscles in COVID-19 patients receiving oxygen therapy in the ICU before and after digital filtering. Methods: This exploratory analysis is part of a cross-sectional study registered on ClinicalTrials.gov (NCT05572853). sEMG signals from the sternocleidomastoid, scalenus, diaphragm, and rectus abdominis muscles were recorded in COVID-19 patients receiving low-flow oxygen therapy. The RMS data were analyzed and processed using Scilab 6.1.1 software before and after applying a filter with a 60 Hz notch and a passband between 20-500 Hz. Results: 71 patients with a mean age of 55 ± 14 years, predominantly male (73.2%), were included. Muscle’s activity remained unchanged after signal filtering, showing higher RMS intensity (pre-filter/post-filter) for the scalene (14.0 ± 8.6 / 8.5 ± 6.2), sternocleidomastoid (12.0 ± 8.8 / 6.8 ± 7.8), diaphragm (11.7 ± 8.1 / 5.4 ± 7.1), and rectus abdominis (10.4 ± 4.7 / 3.1 ± 1.9) muscles. RMS attenuation was significant for all muscles (p &lt; 0.001), with no agreement between pre- and post-filtering from Bland-Altman analysis. Conclusions: The applied digital filter attenuated RMS values while maintaining the same respiratory muscle activation, enhancing signal identification by reducing noise.

Challenges and Advances in the Diagnosis and Management of Neurogenic Thoracic Outlet Syndrome: A Comprehensive Review.

Neurogenic thoracic outlet syndrome (nTOS) is caused by brachial plexus compression in the thoracic outlet. It accounts for 85%-95% of thoracic outlet syndrome (TOS) cases, which may also be caused by compression of the subclavian artery and vein. Compression occurs in the interscalene triangle, costoclavicular space or subpectoralis minor space, with congenital anomalies and repetitive overhead activities as contributing factors. Diagnosis is challenging due to overlapping symptoms with other conditions. Patients commonly report pain, numbness, tingling and weakness in the neck, shoulder and arm, exacerbated by arm elevation. Symptoms related to nTOS may manifest in the distribution of the upper (C5-C6), middle (C7) and lower plexus (C8-T1). Although widely used, provocative tests have varying degrees of sensitivity and specificity and may have high false-positive rates, complicating the diagnosis. Patterns on electrodiagnostic studies provide key diagnostic clues, such as reduced sensory response in the medial antebrachial cutaneous nerve and low compound motor action potential in the median nerve. Imaging techniques like magnetic resonance imaging (MRI), alongside procedures like diagnostic and therapeutic anterior scalene blocks, assist in identifying anatomical abnormalities and predicting surgical outcomes. Management of nTOS involves lifestyle changes, physical therapy, medication and botulinum toxin injections for symptomatic relief. Surgical options may include supraclavicular, transaxillary and infraclavicular approaches, each offering specific benefits based on patient anatomy and surgeon expertise. Minimally invasive techniques, such as video-assisted thoracoscopic surgery (VATS) and robotic surgery, enhance exposure and dexterity, leading to better outcomes. Future research should focus on developing precise diagnostic tools, understanding nTOS pathophysiology, standardising diagnostic criteria and surgical approaches, comparing long-term treatment outcomes and exploring preventive measures to improve patient care and quality of life. Level of Evidence: Level V (Therapeutic).

Division of neuromuscular compartments and localization of the center of the highest region of muscle spindles abundance in deep cervical muscles based on Sihler's staining.

The overall distribution pattern of intramuscular nerves and the regions with the highest spindle abundance in deep cervical muscles have not been revealed. This study aimed to reveal neuromuscular compartmentalization and localize the body surface position and depth of the center of the region of highest muscle spindle abundance (CRHMSA) in the deep cervical muscles. This study included 36 adult cadavers (57.7 ± 11.5 years). The curved line joining the lowest point of the jugular notch and chin tip was designated as the longitudinal reference line (line L), and the curved line connecting the lowest point of the jugular notch and acromion was designated as the horizontal reference line (line H). Modified Sihler's staining, hematoxylin-eosin staining and computed tomography scanning were employed to determine the projection points (P) of the CRHMSAs on the anterior surfaces of the neck. The positions (PH and PL) of point P projected onto the H and L lines, and the depth of each CRHMSA, and puncture angle were determined using the Syngo system. The scalenus posterior and longus capitis muscles were divided into two neuromuscular compartments, while the scalenus anterior and longus colli muscles were divided into three neuromuscular compartments. The scalenus medius muscle can be divided into five neuromuscular compartments. The PH of the CRHMSA of the scalenus muscles (anterior, medius, and posterior), and longus capitis and longus colli muscles, were located at 36.27, 39.18, 47.31, 35.67, and 42.71% of the H line, respectively. The PL positions were at 26.53, 32.65, 32.73, 68.32, and 51.15% of the L line, respectively. The depths of the CRHMSAs were 2.47 cm, 2.96 cm, 2.99 cm, 3.93 cm, and 3.17 cm, respectively, and the puncture angles were 87.13°, 85.92°, 88.21°, 58.08°, and 77.75°, respectively. Present research suggests that the deep cervical muscles can be divided into neuromuscular compartments; we recommend the locations of these CRHMSA as the optimal target for administering botulinum toxin A injections to treat deep cervical muscle dystonia.

Neural Respiratory Drive During Different Dyspnea Relief Positions and Breathing Exercises in Individuals With COPD.

When the work load of the respiratory muscles increases and/or their capacity decreases in individuals with COPD, respiratory muscle activation increases to maintain gas exchange and respiratory mechanics, and perception of dyspnea occurs. The present study aimed to compare diaphragm and accessory respiratory muscle activation during normal breathing, pursed-lip breathing, and breathing control in different dyspnea relief positions, supine and side lying. A cross-sectional study design was used. Sixteen individuals with COPD age between 40-75 y were included. Pulmonary function was evaluated by spirometry, muscle activation by surface electromyography, and dyspnea by the modified Borg scale. Muscle activation was measured in the diaphragm, scalene, sternocleidomastoid, and parasternal muscles. The evaluation was made in the dyspnea relief positions (sitting leaning forward, sitting leaning forward at a table, leaning forward with back against a wall, standing leaning forward, and high lying), seated erect, supine, and side lying. There were significant differences between the 8 positions (P < .001). There was no significant difference in muscle activation between sitting leaning forward and sitting leaning forward at a table position with analyzing post hoc test results (P > .99 for each muscle). However, muscle activation was lower in these 2 positions than in the other positions (P < .001 for each muscle). Muscle activation was greater in the supine position than in the other positions (P < .001 for each muscle). No difference was observed in muscle activation between the seated erect, leaning forward with back against a wall, standing leaning forward, high-lying, or side-lying positions (P > .05 for each muscle with a minimum P value of .09). The use of sitting leaning forward and sitting leaning forward at a table positions together with breathing control may help people with COPD to achieve more effective dyspnea relief and greater energy efficiency.

Endoscopically assisted transaxillary release of the scalene muscles for thoracic outlet syndromes: a comparison with or without first rib resection.

There are several surgical techniques for thoracic outlet syndrome (TOS). However, there have been no reports of endoscopically assisted transaxillary release of the anterior and middle scalene muscles (EATRS), leaving the first rib intact for TOS. We hypothesized that EATRS would achieve a good Quick Disability of the Arm, Shoulder and Hand score. This study aims to present our experience with a new technique for TOS using endoscopy. We chose two surgeries depending on the patient's TOS condition. If the costoclavicular space was under 12mm, we selected endoscopically assisted transaxillary first rib resection (EAFRR). If the costoclavicular space was over 12mm, we selected EATRS. Between January 2021 and December 2022, 31 consecutive surgeries for TOS were performed in our institution. Twenty-five patients underwent EAFRR, and six (19%) underwent EATRS. Since July 2022, EAFRR has been performed under differential lung ventilation. Complete and almost complete relief was achieved in 24 patients (77%), and partial relief was conducted in seven patients (23%) at a mean of 19.7months after surgery. The symptoms improved in all cases. Intraoperative pneumothorax did not occur, and no other complications were observed. Both EAFRR and EATRS were effective and safe surgeries for TOS. Operative time was significantly shorter in EATRS than in EAFRR. We first report EATRS surgery for TOS. EATRS is indicated for patients whose costoclavicular space is preserved before surgery. Good surgical results were obtained after surgery for this indication.

Surgical approach through the anterior scalene muscle resection for invasive tumours in the supraclavicular fossa (with video).

The supraclavicular fossa contains many vital organs to be preserved, such as the brachial plexus, subclavian artery and vertebral artery. Various surgical methods have been reported. However, no well-standardized surgical procedure has been established. Between 2010 and 2020, we performed 28 surgical treatments of the superior mediastinum and supraclavicular fossa. Of these, we retrospectively reviewed seven cases of supraclavicular invasion using a unified surgical technique in which the anterior scalene muscle was resected, and the inter-scalene triangle was approached. We performed claviculectomy in four cases and a transmanubrial approach in three cases. In all cases, by resecting the anterior scalene muscle, the brachial plexus, subclavian artery and vertebral artery were preserved. There were no critical postoperative complications other than tracheostomy and lymphatic leakage. Median bleeding amount and operative time were 438 (range; 76-1144) ml and 328 (range; 246-615) minutes, respectively. The anterior scalene muscle resection method might be a safe and standardized method for preserving the brachial plexus, subclavian artery and vertebral artery.

Structure-Function Relationship of Respiratory Muscles in the mdx Mouse Model of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a genetic neuromuscular disorder, characterized by severe and progressive skeletal muscle weakness, which extends to the respiratory muscles. We have determined that peak inspiratory pressure-generating capacity is preserved in early dystrophic disease in the mdx mouse model of muscular dystrophy, but this early compensation is lost as disease progressesa. We sought to examine the structure-function relationship of obligatory and accessory respiratory muscles in early (4-month) and advanced (16-month) disease. Ex vivo muscle function of obligatory (diaphragm and parasternal) and accessory (sternomastoid, cleidomastoid and scalene) respiratory muscles was assessed in wild-type and mdx mice in early dystrophic disease (n = 8-15 per group). Diaphragm and scalene ex vivo muscle function was assessed in advanced dystrophic disease (n = 10-14 per group). Histology (sirius red, and haematoxylin and eosin) and immunofluorescence (laminin) were used to assess the form of obligatory (diaphragm, parasternal and intercostal) and accessory (sternomastoid, cleidomastoid, scalene and trapezius) respiratory muscles (n=6 per group). Pro-inflammatory cytokine concentrations were examined in muscle homogenates of obligatory and accessory respiratory muscles of wild-type and mdx mice in early and advanced dystrophic disease (n=10 per group). Our study revealed obligatory (diaphragm and parasternal) and accessory (sternomastoid and cleidomastoid) muscle weakness evident in early dystrophic disease. Scalene muscle function is preserved in mdx mice in early disease but is weak in mdx mice in advanced dystrophic disease. Structural remodelling by way of increased collagen deposition (fibrosis), increased central nucleation, increased area of inflammatory cell infiltrate and reduced mean minimal Feret’s diameter (relative atrophy) was evident in obligatory and accessory respiratory muscles in early dystrophic disease. The relative area of collagen deposition in obligatory and accessory respiratory muscles increased with disease progression, but interestingly the increase was most pronounced in the diaphragm muscle. Increased concentration of pro-inflammatory cytokines (IFN-γ, IL-1β, IL-6, KC/GRO, TNF-α, MCP-1, IL-33, MIP-1α, IP-10, MIP-2) was observed in mdx obligatory and accessory muscle homogenates compared to wild-type in early and advanced dystrophic disease. These data widen characterisation of the respiratory control system in mdx mice, potentially revealing novel therapeutic targets. References a O'Halloran KD, Maxwell MN, Marullo AL, Hamilton CP, Ó Murchú SC, Burns DP, Mahony CM, Slyne AD, Drummond SE (2023). Loss of compensation afforded by accessory muscles of breathing leads to respiratory system compromise in the mdx mouse model of Duchenne muscular dystrophy. J Physiol. 601(19):4441-4467. Eli Lilly &amp; Science Foundation Ireland (19/FFP/6628). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

FDG uptake in the cervical muscles after neck dissection: imaging features and postoperative natural course on 18F‑FDG‑PET/CT

PurposeThis study aimed to assess the imaging features and postoperative natural course of 18F-fluorodeoxyglucose (FDG) uptake in the cervical muscles after neck dissection.Materials and methodsThis study included 83 patients who underwent preoperative and postoperative 18F-FDG-PET/CT and were diagnosed with head and neck malignancy after neck dissection. Postoperative 18F-FDG-PET/CT was performed within 5 years after neck dissection. Preoperative and postoperative FDG uptake of the trapezius, sternocleidomastoid, scalene, pectoralis major, and deltoid muscles was visually assessed. Increased postoperative uptake was visually defined as higher postoperative FDG uptake than the preoperative one in the corresponding muscle. The maximum standardized uptake value (SUVmax) was measured in cases with increased postoperative uptakes.ResultsIncreased postoperative uptakes were observed in 43 patients (52%). The trapezius (31/83, 37%), sternocleidomastoid (19/83, 23%), and scalene (12/83, 14%) muscles were involved, as opposed to the pectoralis major and deltoid muscles were not. Increased postoperative uptakes were observed on the dissected side in all 43 patients. Significant differences between SUVmax estimated from the mixed-effects model and postoperative months were observed in the trapezius muscle (Coefficient (β) = −0.038; 95% confidence interval (CI): [−0.047, −0.028]; p < 0.001) and sternocleidomastoid muscle (β = −0.015; 95% CI: [−0.029, −0.001]; p = 0.046).ConclusionsIncreased postoperative uptakes in the cervical muscles were observed on the dissected side in approximately half of the patients after neck dissection. The SUVmax in the trapezius and sternocleidomastoid muscles decreased after surgery over time.

Correlation of cervical-inspiratory-muscle electromyography and oxygen uptake during treadmill walking

For measurements of exercise intensity, an individual's oxygen uptake (V̇O2) is measured with an exhaled gas analyzer that involves a mask, but exercise coaching would benefit if an individual's V̇O2 could be estimated with more easily obtained predictors. We investigated the predictability of V̇O2 by electromyography (EMG) of the neck inspiratory muscles. We analyzed the EMG results of the sternocleidomastoid (EMGst) and scalene (EMGsc) muscles of 14 healthy adults who performed a treadmill exercise load test. Their V̇O2, inspiratory flow rate, and heart rate were simultaneously recorded during the exercise. The exercise load test was performed twice at a ≥2-day interval. The first visit was an incremental exercise test, and the second was a repeated two-load exercise test at levels below and above the participant's ventilatory threshold (VT) as determined in the first test. We observed that the integrated EMG values for each exercise load showed partially significant positive correlations with the EMGst and EMGsc. However, the cervical inspiratory muscle EMGs did not show as high a correlation as the minute ventilation. These results indicate that (i) EMG of the cervical inspiratory muscles could be used to estimate V̇O2, but (ii) these EMG parameters alone should be considered insufficient for estimating V̇O2.

Shear wave elastography for assessing the anterior scalene elasticity in patients with neck pain

PurposeShear-wave elastography (SWE) provides quantitative and absolute metrics for analyzing the elasticity of soft tissues. Despite the anterior scalene muscle (AS) is a key structure in patients with neck pain and nerve compressive syndromes, the majority of SWE studies only included asymptomatic subjects. This study aimed to analyze the Young’s modulus and shear wave speed test–retest reliability in a sample of patients with neck pain symptoms to characterize the AS stiffness. MethodsA diagnostic accuracy study acquiring a set of ultrasound images at C7 level in 42 patients with mechanical neck pain by one experienced examiner. After blinding the participants’ identity, trial and side, the Young’s modulus and shear wave velocity were measured by an independent experienced rater in randomized order. Intra-class correlation coefficients (ICC), standard error of measurement (SEM), minimal detectable changes (MDC) and coefficient of variation (CV%) were calculated. ResultsThe sample reported moderate pain intensity (5.9/10 points) and disability (17.38/100 points). AS stiffness metrics assessed showed no significant differences between males and females, left and right side nor painful and non-painful side. (all, p > 0.05). Intra-examiner reliability was excellent for calculating the Young’s modulus for shear wave speed (ICC > 0.90). ConclusionThe results support the use of this procedure for assessing the AS stiffness in populations with mechanical neck pain as excellent reliability estimates were obtained. However, future research should analyze case-control differences and the association between SWE metrics with clinical severity indicators.

Ultrasound Guided Phrenic Nerve Block for Percutaneous Computer Tomography Guided Lung Biopsy

Abstract The aim of this paper is to present the technique of the ultrasound (US) guided phrenic nerve block (PNB). This is an important adjuvant technique for percutaneous computer-tomography (CT) lung biopsy of nodules situated in the lower lobes, in proximity of the diaphragm, with a diameter of less than 2 cm. These types of nodules have a high location variability during respiration, which makes them hard to be approached for a successful biopsy. US visualization of the nerve is possible after identifying specific landmarks as the sternocleidomastoid and scalene muscle, interval jugular vein and brachial plexus. The phrenic nerve is seen as an oval hypoechogenic structure with no Doppler signal, superficial to the anterior scalene muscle. Ropivacaine can be used as a local anesthetic to induce the PNB. Results: Success of the phrenic nerve block can be assessed by CT scanogram, which shows the ipsilateral hemidiaphragm elevated, and by subsequent lung scans that show little to no location variability of the target lesion. Conclusion. US-guided PNB is a safe and efficient procedure that can help during percutaneous CT-guided lung biopsy of small basal nodules.

Reproducibility of Anterior Scalene Stiffness Measurement with Shear Wave Elastography: An Inter-Examiner Reliability Study.

Although previous studies have highlighted the clinical relevance of the anterior scalene muscle (AS) in patients with neck pain or nerve compressive syndromes, evidence reporting the diagnostic accuracy of shear wave elastography (SWE) for assessing the AS stiffness properties is lacking. This study aimed to analyze the SWE inter-examiner reliability for calculating the Young's modulus and shear wave speed of the AS muscle in asymptomatic subjects. Using a linear transducer, ultrasound images of the antero-lateral neck region at the C7 level were acquired in 35 healthy volunteers by one experienced examiner and one novice examiner. After codifying the images to blind the participants' identity, the trial, and the side, Young's modulus and shear wave speed were obtained by an independent experienced rater in randomized order. Intra-class correlation coefficients (ICC), standard error of measurement (SEM), minimal detectable changes (MDC), and coefficient of variation (CV%) were calculated. The assessed AS metrics showed no side-to-side differences (p>0.05). Sex differences were found for muscle size (p=0.002), but muscle brightness and stiffness were similar (p>0.05). Inter-examiner reliability was good for determining the AS muscle stiffness (ICC = 0.881 for Young's modulus and 0.850 for shear wave speed). The obtained results suggest that assessing the AS stiffness properties in asymptomatic subjects is a reliable procedure. Further studies should verify the SWE capacity for discriminating healthy and clinical populations and identify potential factors contributing to the variance of measurement errors.