Ultrasonography of the brachial plexus, normal appearance and practical applications

Systematic approach to obtain axillary arterial access for pediatric heart catheterizations

Background

Axillary arterial access (AAA) in pediatric heart catheterizations is undervalued.

Methods

We retrospectively reviewed children with congenital heart diseases (CHDs) who received trans-axillary arterial catheterizations between January 2019 and February 2023. We aimed ultrasound-guided punctures in the proximal two-thirds of axillary arteries with diameters ≥2 mm to insert 7 cm/4 Fr short introducers. We administrated intra-arterial verapamil (1.25 mg) and heparin (100 UI/kg). We infiltrated per-operatively 2% lignocaine (10 mg) for arterial spasms, long sheaths use (≥5 Fr), and ≥60 min procedures in <3 kg patients.

Results

We identified 30 patients (66.7% males) with a median age of 1.1 months (IQR, 0.3-5.4), and a median weight of 3.1 kg (IQR, 2.7-3.7). 5/30 patients had six redo interventions after a median of 3.9 months (IQR, 1.7-5.1). Overall, 27/36 procedures were interventional, including 6 aortic valvuloplasties, 6 balloon angioplasties, and 15 stenting procedures. The median arterial axillary angiographic diameter was 2.6 mm (IQR, 2.4-3). Access was right-sided in 23/36 (63.9%) procedures and obtained using 21G/2.5 cm bevel needles in 25/36 (69.4%) procedures. No hemodynamical change occurred after introducing spasmolytic drugs. The median fluoroscopy time was 26.1 min (IQR, 19.2-34.8). There were two self-resolving arterial dissections, one sub-occlusive arterial thrombosis (resolved with 6 weeks of enoxaparin), and one occlusive arterial thrombosis (resolved with alteplase thrombolysis and 6 weeks of enoxaparin). Median follow-up was 11.7 months (IQR, 8-17.5). Four patients with complex univentricular hearts died from non-procedural causes at a median of 40 days (IQR, 31-161) postoperative.

Conclusion

Systematic approach for AAA is the key to success and unlocks the many potentials of trans-axillary pediatric cardiology interventions.

Brachial Plexus Nerve Injuries and Disorders

Multimodality imaging of the brachial plexus is essential to accurately localize the lesion and characterize the pathology and site of injury. A combination of computed tomography (CT), ultrasound, and MR imaging is useful along with clinical and nerve conduction studies. Ultrasound and MR imaging in combination are effective to accurately localize the pathology in most of the cases. Accurate reporting of the pathology with dedicated MR imaging protocols in conjunction with Doppler ultrasound and dynamic imaging provides practical and useful information to help the referring physicians and surgeons to optimize medical or surgical treatment regimens.

Elective brachial plexus decompression in neurogenic thoracic outlet syndrome

We aimed to evaluate functional outcome following elective brachial plexus decompression by compressive fibrous band resection and limited on-demand bone abnormality resection in patients with neurogenic thoracic outlet syndrome (N-TOS). A retrospective continuous observational study was conducted in 17 patients (15 women and 2 men), with a mean age of 42 years, operated on between 2013 and 2021. Twenty brachial plexus decompressions were performed, for 13 objective and 7 subjective N-TOSs, including 3 recurrent N-TOSs. At last follow-up, outcomes were evaluated in terms of residual pain, paresthesia and hand motor deficit, plus patient-reported assessment and Quick-DASH functional scoring. No postoperative complications occurred. At a median follow-up of 12 months (range 6-48 months), complete pain relief and paresthesia resolution were found in 11/15 and 9/14 cases, respectively. All patients reported that their symptoms had improved. In contrast, hand muscle atrophy persisted in all cases (n = 11). Sensorimotor recovery seemed to be poorer and mean Quick-DASH score better in objective than subjective N-TOS patients. Elective brachial plexus decompression seemed to be a safe procedure, providing constant improvement in subjective symptoms related to lower trunk irritation. However, nerve release did not provide hand muscle recovery in patients with objective N-TOS. LEVEL OF EVIDENCE: IV.

Case report: Brachial plexopathy caused by malignant peripheral nerve sheath tumor and review of the literature

Brachial plexopathy (BP) is easily misdiagnosed due to its complexity and varying clinical presentation. Malignant peripheral nerve sheath tumors (MPNST) can accumulate in the brachial plexus and share symptoms with BP, which may hinder the differential diagnosis between BP induced by radiation or metastases, and MPNST-derived BP, in patients with a history of breast cancer and radiation exposure. A 34-year-old Chinese female presented with MPNST. The tumor involved the brachial plexus. She had a history of breast cancer and radiotherapy. The first consideration was radiation- or breast cancer metastasis-derived BP. Clinical examination was performed. Finally, a diagnosis of MPNST of the brachial plexus was made, which guided an accurate treatment plan. This report highlights the importance of correctly diagnosing BP etiology for guiding precise treatment. BP caused by MPNST needs to be considered in clinical practice, and biopsy plays a central role in the differential diagnosis. Complete local surgical resection can prolong survival of patients with MPNST and improve treatment prognosis.

Correlation of age and the diameter of the cervical nerve roots C5 and C6 during the first 2 years of life analyzed by high-resolution ultrasound imaging

AIM

To analyze the increase in diameter of the nerve roots C5 and C6 in early childhood.

METHODS

The nerve roots of 56 children aged 0 days to 10 years (47 younger than 2 years) were examined by high-resolution ultrasound imaging. The correlation of diameter and age was statistically tested and a logarithmic regression analysis was performed to develop a logarithmic growth model.

RESULTS

The increase in nerve root diameter is greatest during the first 2 years of life and then the growth rate decreases steadily. The relationship between age and diameter follows a logarithmic curve (p < 10^-8 ).

INTERPRETATION

The main increase in the diameter of the nerve roots happens in the first 2 years of life. Comparing data from a previous study, our data also suggest that the maturation of the proximal part of the median nerve is comparable to the maturation of its distal segments. This suggests a synchronous maturation of the axons and myelin sheath for the whole extent of the nerve, from the radix to its very distal part.

WHAT THIS PAPER ADDS

Normative values for the size of the cervical nerve roots C5 and C6; an insight into the maturation of the proximal parts of the peripheral nervous system; and the correlation between age and cervical root diameter.

Diagnostic Ability of Ultrasonography in Brachial Plexus Root Injury at Different Stages Post-trauma

Brachial plexus (BP) root injury often results in disability of the upper extremities. Improvements in high-frequency ultrasonography have enabled the visualization of BP nerve roots. This study was aimed at quantifying the diagnostic accuracy of ultrasonography in BP root injury at different stages post-trauma. A consecutive series of 170 patients with BP root injury between 2015 and 2019 were studied retrospectively and divided into three groups on the basis of time between injury and ultrasound examination (≤1 mo, 1-3 mo, >3 mo). Diagnosis of complete BP root injury under ultrasound was determined using a pre-defined criterion, including pseudomeningocele, retraction and rupture. Diagnostic accuracy was calculated based on surgical findings and intra-operative electrophysiological tests. Rates of detection of the cervical (C5-C8) and thoracic (T1) nerve roots under ultrasound were 99.4%, 99.4%, 99.4%, 95.9% and 79.4%, respectively. The sensitivity for complete BP root injury was 0.74, and the specificity was 0.91. No significant differences in sensitivity or specificity were observed across time stages. Ultrasound exhibited substantial consistency with surgical findings (κ = 0.70) for complete BP root injury at any stage post-injury. Ultrasound can be an optional method of diagnosis of complete BP root injury at an early stage post-injury.

Characterization of Tissue Scaffolds Using Synchrotron Radiation Microcomputed Tomography Imaging

Distinguishing from other traditional imaging, synchrotron radiation microcomputed tomography (SR-μCT) imaging allows for the visualization of three-dimensional objects of interest in a nondestructive and/or in situ way with better spatial resolution, deep penetration, relatively fast speed, and/or high contrast. SR-μCT has been illustrated promising for visualizing and characterizing tissue scaffolds for repairing or replacing damaged tissue or organs in tissue engineering (TE), which is of particular advance for longitudinal monitoring and tracking the success of scaffolds once implanted in animal models and/or human patients. This article presents a comprehensive review on recent studies of characterization of scaffolds based on SR-μCT and takes scaffold architectural properties, mechanical properties, degradation, swelling and wettability, and biological properties as five separate sections to introduce SR-μCT wide applications. We also discuss and highlight the unique opportunities of SR-μCT in various TE applications; conclude this article with the suggested future research directions, including the prospective applications of SR-μCT, along with its challenges and methods for improvement in the field of TE.

Update on the thoracic outlet syndrome and plexus brachial syndrome: Specific clinical examination (for all) and rehabilitation protocol

The diagnosis of uncomplicated forms of thoracobrachial outlet syndrome (TOS) and brachial plexus stretching syndrome (BPSS) is imprecise due to the lack of clear differentiation between dynamic vascular or neurological compression and brachial plexus stretching without vascular compression. After a review of literature, we propose and describe a simple way for clinical assessment of TOS, BPSS or association of both comprising 1 clinical sign and 2 manoeuvres. This clinical assessment can be performed by the medical doctor, the physiotherapist and the surgeon. The clinical diagnosis is essential because it will dictate the rehabilitation treatment. We propose and describe also a rehabilitation protocol comprising 10 phases with modulation of exercises according to clinical form (TOS, BPSS or association) and/or severity of symptoms. The physiotherapist has a capital role and is the guarantor of the effectiveness of the medical treatment. In France, a training is now available thanks to personal continuous development for diagnosis and treatment of TOS and BPSS. This is essential in order to propose an optimal care to patients.

Imaging of non-specific complaints of the arm, neck, and/or shoulder (CANS): role of the scalene muscles and piercing variants in neurogenic thoracic outlet syndrome

Complaints of the arm, neck and/or shoulder (CANS) are common in the general population (40%) and workers (30%) and have significant economic impact. Twenty-three conditions have been designated as specific CANS. Cases where no cause is identified are reported as non-specific CANS; these cases make up the majority of CANS. Non-specific CANS presentations overlap with clinical entities including cervicobrachial and scalene myofascial syndromes that are associated with neurogenic thoracic outlet syndrome (NTOS). The scalene muscles have been identified as the commonest site of NTOS, although this has been reported to be functional and in conjunction with cervicothoracic junction variants that compromise the brachial plexus lower trunk. Anatomical variants in relation to both the scalene muscles and brachial plexus are not widely recognised in the clinical and imaging literature; however, pass-through and pass-over (or "piercing") variants of the brachial plexus upper trunk and scalene muscles have been well described in the anatomical and anaesthetic literature. In this review, we demonstrate the presence and describe the imaging of scalene muscle pathology and variant muscle-brachial plexus anatomy affecting the upper trunk that are underdiagnosed causes of non-specific CANS presentations and NTOS.

Anatomy, Imaging, and Pathologic Conditions of the Brachial Plexus

The brachial plexus is an intricate anatomic structure with an important function: providing innervation to the upper extremity, shoulder, and upper chest. Owing to its complex form and longitudinal course, the brachial plexus can be challenging to conceptualize in three dimensions, which complicates evaluations in standard orthogonal imaging planes. The components of the brachial plexus can be determined by using key anatomic landmarks. Applying this anatomic knowledge, a radiologist should then be able to identify pathologic appearances of the brachial plexus by using imaging modalities such as MRI, CT, and US. Brachial plexopathies can be divided into two broad categories that are based on disease origin: traumatic and nontraumatic. In the traumatic plexopathy group, there are distinct imaging findings and management methods for pre- versus postganglionic injuries. For nontraumatic plexopathies, having access to an accurate patient history is often crucial. Knowledge of the timing of radiation therapy is critical to diagnosing post-radiation therapy brachial plexopathy. In acute brachial neuritis, antecedent stressors occur within a specific time frame. Primary and secondary tumors of the brachial plexus are not uncommon, with the most common primary tumors being peripheral nerve sheath tumors. Direct extension and metastasis from primary malignancies such as breast and lung cancer can occur. Although diagnosing a brachial plexus anomaly is potentially perplexing, it can be straightforward if it is based on foundational knowledge of anatomy, imaging findings, and pathologic features. ^©RSNA, 2020.

Cross-sectional area reference values for peripheral nerve ultrasound in adults: A systematic review and meta-analysis-Part III: Cervical nerve roots and vagal nerve

BACKGROUND AND PURPOSE

Measurement of the cross-sectional area (CSA) of cervical nerve roots using ultrasound is useful in the evaluation of inflammatory polyneuropathies, and measurement of CSA of the vagal nerve might give information about involvement of the autonomic nervous system. We performed a systematic review and meta-analysis of published CSA reference values for cervical nerve roots and vagal nerve.

METHODS

We included available-to-date nerve ultrasound studies on healthy adults and provide meta-analysis for CSA of the following nerves: cervical nerve roots C5, C6, and C7 as well as vagal nerve in the carotid sheath at the carotid bifurcation level. We report regression and correlation analyses for age, gender, height, weight, and geographic continent.

RESULTS

We included 11 studies with 885 healthy volunteers (mean age = 42.7 years) and 3149 examined nerve sites. Calculated mean pooled CSA of C5 root was 5.6 mm² (95% confidence interval [CI] = 4.6-6.7 mm² , n = 911), of C6 root was 8.8 mm² (95% CI = 7.4-10.3 mm² , n = 909), of C7 root was 9.5 mm² (95% CI = 8.0-10.9 mm² , n = 909), and of vagal nerve was 2.2 mm² (95% CI = 1.5-2.9 mm² , n = 420). No heterogeneity was found across studies for any site. Subgroup analysis revealed no significant effects of age, gender, height, weight, and geographic continent on CSA for any of these nerve sites.

CONCLUSIONS

We provide the first meta-analysis on CSA reference values for the cervical nerve roots and the vagal nerve, with no heterogeneity of reported CSA values at all nerve sites. Our data facilitate the goal of an international standardized evaluation protocol.

Enlarged Brachial Plexus Nerve Found During Ultrasound-Guided Peripheral Nerve Block Diagnosed as Charcot-Marie-Tooth Disease: A Case Report

Ultrasound-guided peripheral nerve block (PNB) has become a popular anesthetic procedure. We report a case of an enlarged brachial plexus nerve noted on ultrasonographic images, as part of PNB, which was diagnosed postoperatively as Charcot-Marie-Tooth disease (CMTD), an inherited neurological disorder of the peripheral nerves. Although nerve enlargement is characteristic of demyelinating diseases such as CMTD, the use of ultrasonography in the diagnosis of neurological disorders is a developing area for neurologists and anesthesiologists can lack knowledge in this emerging field. Unusual nerve presentation on ultrasonographic images during PNB anesthetic procedures should be recognized as being indicative of underlying neurologic disorders. This case highlights that increased awareness of the diagnosis of underlying neurologic disorders by ultrasonography would assist the general practice of PNB in anesthetic medicine. This is especially important as underlying neurological conditions can have important consequences for patient-appropriate anesthesia and may inform best anesthetic practice. A new category, “neurological disorder on ultrasound image”, should be introduced to PNB knowledge in anesthetic field.

Efficacy of a single injection compared with triple injections using a costoclavicular approach for infraclavicular brachial plexus block during forearm and hand surgery: A randomized controlled trial

OBJECTIVES

It was recently proposed that a costoclavicular (CC) approach can be used in ultrasound (US)-guided infraclavicular brachial plexus block (BPB). In this study, we hypothesized that triple injections in each of the 3 cords in the CC space would result in a greater spread in the 4 major terminal nerves of the brachial plexus than a single injection in the CC space without increasing the local anesthetic (LA) volume.

METHODS

Sixty-eight patients who underwent upper extremity surgery randomly received either a single injection (SI group, n = 34) or a triple injection (TI group, n = 34) using the CC approach. Ten milliliters of 2% lidocaine, 10 mL of 0.75% ropivacaine, and 5 mL of normal saline were used for BPB in each group (total 25 mL). Sensory-motor blockade of the ipsilateral median, radial, ulnar, and musculocutaneous nerves was assessed by a blinded observer at 5 minutes intervals for 30 minutes immediately after LA administration.

RESULTS

Thirty minutes after the block, the blockage rate of all 4 nerves was significantly higher in the TI group than in the SI group (52.9% in the SI group vs 85.3% in the TI group, P = .004). But there was no significant difference in the anesthesia grade between the 2 groups (P = .262). The performance time was similar in the 2 groups (3.0 ± 0.9 minutes in the SI group vs 3.2 ± 1.2 minutes in the TI group, respectively; P = .54).

DISCUSSION

The TI of CC approach increased the consistency of US-guided infraclavicular BPB in terms of the rate of blocking all 4 nerves without increasing the procedure time despite administering the same volume of the LA.

Ultrasound reference values of C5, C6, and C7 brachial plexus roots at the interscalene groove

OBJECTIVES

The objective of this study is to estimate the reference values of the brachial plexus roots at the interscalene groove. The physical and demographic characteristics of 59 healthy adult volunteers were studied. The CSA reference values and their correlations with weight, height, age, body mass index (BMI).

METHODS

Fifty nine (27 males, 32 females) subjects were enrolled in the study. The mean cross sectional area of C5, C6 and C7 nerve roots were obtained.

RESULTS

The mean CSA of the brachial plexus roots was as follows: C5 nerve root was 5.1 mm² (range 1.7-11.1 ± 1.9 SD), C6 nerve root CSA 5.8 mm² (range 1.7-12 ± 2.4 SD), and C7 nerve root 6.3 (range 1.6-19.6 ± 3.4 SD). There was a significant statistical difference between both sexes in our study. No statistical significant difference in tissue stiffness between dominant and nondominant hands. No statistical correlation was found between the CSA of the cervical nerve roots and different demographic factors. There was a positive statistical correlation between the CSA of C5 and both C6 and C7 nerve roots. Also positive significant statistical correlation was noted between the CSA of C6 and C7 nerve roots.

CONCLUSION

The CSA reference values of the C5-C7 nerve roots has been determined in asymptomatic individuals and can serve as a reference when studying pathological conditions of these structures.

Diffusion tensor imaging of the roots of the brachial plexus: a systematic review and meta-analysis of normative values

Purpose

Diffusion tensor magnetic resonance imaging (DTI) characterises tissue microstructure and provides proxy measures of myelination, axon diameter, fibre density and organisation. This may be valuable in the assessment of the roots of the brachial plexus in health and disease. Therefore, there is a need to define the normal DTI values.

Methods

The literature was systematically searched for studies of asymptomatic adults who underwent DTI of the brachial plexus. Participant characteristics, scanning protocols, and measurements of the fractional anisotropy (FA) and mean diffusivity (MD) of each spinal root were extracted by two independent review authors. Generalised linear modelling was used to estimate the effect of experimental conditions on the FA and MD. Meta-analysis of root-level estimates was performed using Cohen's method with random effects.

Results

Nine articles, describing 316 adults (1:1 male:female) of mean age 35 years (SD 6) were included. Increments of ten diffusion sensitising gradient directions reduced the mean FA by 0.01 (95% CI 0.01, 0.03). Each year of life reduced the mean MD by 0.03 × 10^-3 mm²/s (95% CI 0.01, 0.04). At 3-T, the pooled mean FA of the roots was 0.36 (95% CI 0.34, 0.38; I ² 98%). The pooled mean MD of the roots was 1.51 × 10^-3 mm²/s (95% CI 1.45, 1.56; I ² 99%).

Conclusions

The FA and MD of the roots of the brachial plexus vary according to experimental conditions and participant factors. We provide summary estimates of the normative values in different conditions which may be valuable to researchers and clinicians alike.

Ultrasonographic anatomy of the long thoracic nerve: A reappraisal using high frequency (24-MHz) probe

PURPOSE

The purpose of this study was to analyze the potential of ultrasound with a high frequency probe (24-MHz) in the assessment of the long thoracic nerve (LTN) and describe ultrasonographic landmarks that can be used for standardization.

MATERIAL AND METHODS

Ultrasonography analysis of the LTN was done on 2 LTNs in a cadaver specimen and then on 30 LTNs in 15 healthy volunteers (12 men, 3 women; mean age, 28.8±3.8 [SD] years; age range: 24-39 years) by two independent radiologists (R1 and R2) using a 24-MHz probe. Interrater agreement was assessed using Kappa test (K) and intraclass correlation coefficient (ICC).

RESULTS

In the cadaver, dissection confirmed that the India ink was injected near the LTN in the middle scalene muscle. In volunteers, visibility of the LTN above the clavicle was highly reproducible for the branches arising from C5 (R1: 87% [26/30]; R2: 90% [27/30]; K=0.83) and from C6 (R1: 100% [30/30]; R2: 97% [29/30]; K=0.94). Where the nerve emerged from the middle scalene muscle, the mean diameter was 0.85±0.24 (SD) mm (range: 0.4-1.6mm) for R1 and 0.9±0.23 (SD) mm (range: 0.4-1.7mm) for R2 (ICC: 0.96; 95% CI: 0.92-0.98%). Along the thoracic wall, where LTN run along the lateral thoracic artery, the mean diameter was 0.83±0.19 (SD) mm (range: 0.5-1.27mm) for R1 and 0.89±0.21 (SD) mm (range: 0.6-1.2mm) for R2 (ICC: 0.86; 95% CI: 0.72-0.93%).

CONCLUSION

The LTN can be analyzed with ultrasound using high-frequency probe by using the C5 and C6 roots, the middle scalene muscle above the clavicle and the lateral thoracic artery on the chest wall as landmarks.

Emerging Role of Large-bore Percutaneous Axillary Vascular Access: A Step-by-step Guide

Advances in transcatheter structural heart interventions and temporary mechanical circulatory support have led to increased demand for alternative sites for large-bore vascular access. Percutaneous axillary artery access is an appealing alternative to femoral access in patients with peripheral arterial disease, obesity or for prolonged haemodynamic support where patient mobilisation may be valuable. In particular, axillary access for mechanical circulatory support allows for increased mobility while using the device, facilitating physical therapy and reducing morbidity associated with prolonged bed rest. This article outlines the basic approach to percutaneous axillary vascular access, including patient selection and procedure planning, anatomic axillary artery landmarks, access techniques, sheath removal and management of complications.

Diagnostic Function of 3-Tesla Magnetic Resonance Imaging for the Assessment of Brachial Plexus Injury

Background:

This study aimed to evaluate the diagnostic function of 3-Tesla (T) magnetic resonance imaging (MRI) during the assessment of brachial plexus injury (BPI), in comparison with intraoperative findings.

Methods:

A retrospective study was performed on 60 patients (47 men and 13 women), who had clinical manifestations of BPI, underwent 3T MRI of the brachial plexus, and were surgically treated at the Viet Duc and Vinmec Times City hospitals, in Hanoi, Vietnam, from March 2016 to December 2019. Preganglionic and postganglionic lesion features were identified on MRI. The diagnostic function of MRI features for the determination of BPI was evaluated and correlated with intraoperative findings.

Results:

The root avulsion and pseudomeningocele preganglionic injuries were observed in 57% and 43% of MRIs, respectively, and were commonly observed at the C7 and C8 roots. Nerve disruption and never edema were observed in 47.56% and 33.53% of MRIs, respectively, and were commonly observed at the C5 and C6 roots. The sensitivity, specificity, accuracy, positive prognostic value, and negative prognostic value of 3T MRI were 64.12%, 92.90%, 80.33%, 87.50%, and 76.96%, respectively, for the diagnosis of total avulsion, and 68.52%, 83.33%, 80.67%, 47.44%, and 92.34%, respectively, for the diagnosis of nerve disruption.

Conclusion:

MRI offers valuable details regarding the location, morphology, and severity of both preganglionic and postganglionic injuries during the preoperative diagnosis of BPI. However, this modality played a moderate diagnostic role. Therefore, 3T MRI should be used as a supplemental evaluation, coupled with clinical tests and electromyography, to determine the most appropriate treatment strategies for BPI patients.

Sonographic Pearls for Imaging the Brachial Plexus and Its Pathologies

The brachial plexus (BP) is a complicated neural network, which may be affected by trauma, irradiation, neoplasm, infection, and autoimmune inflammatory diseases. Magnetic Resonance Imaging is the preferred diagnostic modality; however, it has the limitations of high cost and lack of portability. High-resolution ultrasound has recently emerged as an unparalleled diagnostic tool for diagnosing postganglionic lesions of the BP. Existing literature describes the technical skills needed for prompt ultrasound imaging and guided injections for the BP. However, it remains particularly challenging for beginners to navigate easily while scanning its different parts. To address this, we share several “clinical pearls” for the sonographic examination of the BP as well as its common pathologies.

High definition ultrasound imaging of the individual elements of the brachial plexus above the clavicle

Background and objectives

Ultrasonography of the brachial plexus (BP) has been described but there are limited data on visualization of the T1 ventral ramus and the inferior trunk. This prospective observational study aimed to evaluate a high definition ultrasound imaging technique to systematically identify the individual elements of the BP above the clavicle.

Methods

Five healthy young volunteers underwent high definition ultrasound imaging of the BP above the clavicle. The ultrasound scan sequence (transverse oblique scan) commenced at the supraclavicular fossa after which the transducer was slowly swept cranially to the upper part of the interscalene groove and then in the reverse direction to the supraclavicular fossa. The unique sonomorphology of the C7 transverse process was used as the key anatomic landmark to identify the individual elements of the BP in the recorded sonograms.

Results

The neural elements of the BP that were identified in all volunteers included the ventral rami of C5–T1, the three trunks, divisions of the superior trunk, and formation of the inferior trunk (C8–T1). The C6 ventral ramus exhibited echogenic internal septation with a split (bifid) appearance in four of the five volunteers. In three of the four volunteers with a bifid C6 ventral ramus, the C7 ventral ramus was also bifid.

Conclusion

We have demonstrated that it is feasible to accurately identify majority of the main components of the BP above the clavicle, including the T1 ventral ramus and the formation of the inferior trunk, using high definition ultrasound imaging.

Trial registration number

ChiCTR1900021749.

Sonographic measurements of normal C5-C8 nerve roots in children

Introduction

The aim of this study was to use ultrasound to measure the cervical nerve roots in normal children to determine normal reference values.

Methods

A total of 441 children of different ages at the Children's Hospital of Chongqing Medical University were examined by ultrasound. The diameter, circumference, and cross‐sectional area of the nerve roots were measured.

Results

Ultrasonographic measurements were consistent with the ranking C5 < C6 < C7. The C8 nerve root was thicker than C7 in 60% of the participants. The nerve root measurements increased with increasing age, height, weight, and body surface area.

Discussion

Normal reference ranges of the cervical nerve roots in children of different ages were established, and can serve as the basis for measurement in future studies.

Ultrasound-Guided Versus Landmark-Based Approach to the Distal Suprascapular Nerve Block: A Comparative Cadaveric Study

PURPOSE

To compare the accuracy of distal suprascapular nerve (dSSN) blockade performed with the use of ultrasound-guided regional anesthesia (USRA) versus with a landmark-based approach (LBA). A secondary aim was to describe the anatomic features of the sensory branches of the dSSN.

METHODS

USRA and LBA were performed in 15 shoulders each from 15 cadavers (total of 30 shoulders). Then, 10 mL of methylene blue‒infused ropivacaine 0.75% was injected into the dSSN. Simultaneously, 2.5 mL of red latex solution was injected to identify the position of the needle tip. The division and distribution of the sensory branches originating from the SSN were described.

RESULTS

The tip of the needle was identified at 1.3 cm (range, 0-5.2 cm) and 1.5 cm (range, 0-4.5 cm) with USRA and the LBA, respectively (P = .90). Staining diffused past the origin of the most proximal sensory branch in 27 cases. The most proximal sensory branch arose 2.5 cm from the suprascapular notch. Among the 3 failures that occurred in the USRA group, the sensory branches also failed to be marked. All 30 dSSNs gave off 3 sensory branches, which innervated the posterior glenohumeral capsule, the subacromial bursa, and the coracoclavicular and acromioclavicular ligaments.

CONCLUSIONS

An LBA is as reliable and accurate as US guidance for anesthetic blockade of the dSSN. Marking of the suprascapular nerve must be proximal to the suprascapular notch to involve the 3 sensory branches in the anesthetic blockade.

CLINICAL RELEVANCE

The present study demonstrates that a landmark-based approach to anesthetic blockade of the distal suprascapular nerve is accurate and can be performed by orthopaedic surgeons lacking experience in ultrasound-guided anesthetic techniques.

Ultrasound-Guided Proximal and Distal Suprascapular Nerve Blocks: A Comparative Cadaveric Study

Objectives

The primary aim of our study was to evaluate and compare the accuracy of ultrasound (US)-guided distal suprascapular nerve (dSSN) and proximal SSN (pSSN) blocks. Secondary aims were to compare the phrenic nerve involvement between groups and to describe the anatomical features of the sensory branches of the dSSN.

Methods

pSSN and dSSN blocks were performed in 14 cadavers (28 shoulders). Ten mL of 0.2% ropivacaine colored with methylene blue was injected under US guidance. Accuracy was determined using SSN staining and the distance between predefined anatomical landmarks and the targeted SSN. The phrenic nerve (PN) was judged to be colored or not. The distribution of the sensory branches that originate from the 14 dSSNs is described. Quantitative data are expressed as median (range).

Results

The pSSN was dyed more frequently than the dSSN (13 vs 11, P = 0.59). The targeted SSN was close to the suprascapular notch (1.3 [0–5.2] cm) and the origin of the SSN (1.4 [0.2–4.5] cm) for dSSN and pSSN blocks, respectively (P = 0.62). For dSSN blocks, the most frequent injection site was the supraspinous fossa. Three PNs were marked in pSSN blocks, compared with none in dSSN blocks (P = 0.22). Three sensory branches were identified for all 14 dSSNs: the medial subacromial branch, the lateral subacromial branch, and the posterior glenohumeral branch.

Conclusions

US-guided pSSN and dSSN blocks can be realized with accuracy. A distal approach to the SSN could be an alternative to interscalene brachial plexus block for the management of postoperative pain after shoulder surgery in high–respiratory risk patients.

Distal suprascapular nerve block-do it yourself: cadaveric feasibility study

BACKGROUND

A bone landmark-based approach (LBA) to the distal suprascapular nerve (dSSN) block is an attractive "low-tech" method available to physicians with no advanced training in regional anesthesia or ultrasound guidance. The primary aim of this study was to validate the feasibility of an LBA to blockade of the dSSN by orthopedic surgeons using anatomic analysis. The secondary aim was to describe the anatomic features of the sensory branches of the dSSN.

MATERIALS AND METHODS

An LBA was performed in 15 cadaver shoulders by an orthopedic resident. Then, 10 mL of methylene blue-infused 0.75% ropivacaine was injected around the dSSN; 2.5mL of red latex solution was also injected to identify the position of the needle tip. The division and distribution of the sensory branches that originate from the suprascapular nerve were described.

RESULTS

The median distance between the dSSN and the site of injection was 1.5 cm (0-4.5 cm). The most common injection site was at the proximal third of the scapular neck (n = 8). Fifteen dSSNs were stained proximal to the origin of the most proximal sensory branch. All 15 dSSNs gave off 3 sensory branches that innervated the posterior glenohumeral capsule, the subacromial bursa, and the coracoclavicular and acromioclavicular ligaments.

CONCLUSIONS

An LBA for anesthetic blockade of the dSSN by an orthopedic surgeon is a simple, reliable, and accurate method. Injection close to the suprascapular notch is recommended to involve the dSSN proximally and its 3 sensory branches.

Sonographic evaluation of uncommonly assessed upper extremity peripheral nerves: anatomy, technique, and clinical syndromes

Targeted ultrasound of the median, ulnar, and radial nerves is a well-established technique for suspected upper extremity peripheral neuropathy. However, sonographic imaging of the brachial plexus and smaller peripheral nerve branches is more technically difficult and the anatomy is less familiar to many radiologists. As imaging techniques improve, many clinicians refer patients for imaging of previously less-familiar structures. In addition, some patients may present with injuries that could involve local neurovascular structures. Finally, patients presenting with isolated peripheral neuropathies may be referred for perineural injections with local anesthetic for diagnostic purposes, or steroid for therapeutic reasons. This requires sonologists to have a firm understanding of the courses of these nerves and the surrounding anatomic landmarks that can be used to accurately identify and characterize them. We discuss clinical syndromes referable to specific peripheral nerve branches in the upper extremity, the relevant anatomy, and sonographic technique.

Brachial plexus schwannoma mimicking cervical lymphadenopathy: A case report with emphasis on imaging features

RATIONALE

Brachial plexus schwannomas are rare benign tumors that are derived from Schwann cells. Because they are rare, and because of the complexity of the anatomy of the neck, these tumors can be a challenge to diagnose for radiologists and clinicians. In the present study, we describe a clinical case of brachial plexus schwannoma detected on ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI), and presenting as a palpable neck mass.

PATIENT CONCERNS

A 49-year-old woman had a palpable mass in the right neck, which had been there for the last 1 year. Metastatic cervical lymphadenopathy was suspected in the primary health clinic; therefore, the patient was referred to our hospital.

DIAGNOSES

The right neck mass was a well-circumscribed oval soft tissue mass on US, CT, and MRI. US-guided core needle biopsy was performed and the mass was proved to be a schwannoma.

INTERVENTIONS

The patient did not undergo surgical excision because the brachial plexus schwannoma was small and there was no accompanying neurological symptom.

OUTCOMES

The patient is being followed up regularly at the outpatient department.

LESSONS

Brachial plexus schwannoma should be considered for a differential diagnosis in patients with a palpable neck mass, and imaging studies play an important role in diagnosing the brachial plexus schwannoma.

Shear Wave and Strain Elastographic Features of the Brachial Plexus in Healthy Adults: Reliability of the Findings-a Pilot Study

OBJECTIVES

To determine the sonoelastographic findings for the normal brachial plexus via shear wave elastography (SWE) and strain elastography (SE) and the reliability of the measurements.

METHODS

Thirty-nine healthy adult volunteers were included in the study. The brachial plexus was evaluated with SWE and SE at the interscalene region by 2 observers separately, and the observers were unaware of each other's outcomes. The elastic modulus (kilopascals), shear wave velocity (SWV, meters per second), and strain ratio were obtained. Elasticity patterns on SE were assessed as hard, intermediate, and soft. An intraclass correlation coefficient analysis was performed for determining the reliability of sonoelastographic findings. The correlation of sonoelastographic features with age and sex was investigated.

RESULTS

The volunteers included 13 men and 26 women. The mean age of the participants ± SD was 36.2 ± 7.8 (range, 25-56) years. The mean elasticity modulus values of the brachial plexus for observers 1 and 2 were 17.03 (95% confidence interval [CI], 15.03, 19.03) and 13.83 (95% CI, 12.23, 15.43) kPa, respectively; the SWVs were 2.24 (95% CI, 2.12, 2.36) and 2.04 (95% CI, 1.93, 2.15) m/s; and the strain ratios were 1.20 (95% CI, 1.18, 1.25) 1.38 (95% CI, 1.22, 1.54). The elasticity pattern was mostly intermediate stiffness for both observers (n = 72 [92.3%]; n = 75 [96.1%]). The intraclass correlation coefficient was poor to moderate and statistically significant for the elastic modulus, SWV, and elasticity pattern (P < .05 for all parameters). The sonoelastographic characteristics of the brachial plexus had no correlation with age or sex.

CONCLUSIONS

The reliability and reproducibility of sonoelastography of the brachial plexus are low, and the appropriateness of this technique in this manner is controversial.

Somatotopic Fascicular Lesions of the Brachial Plexus Demonstrated by High-Resolution Magnetic Resonance Neurography

OBJECTIVES

The aim of this study was to evaluate whether high-resolution brachial plexus (BP) magnetic resonance neurography (MRN) is capable of (1) distinguishing patients with compressive neuropathy or noncompressive plexopathy from age- and sex-matched controls, (2) discriminating between patients with compressive neuropathy and noncompressive plexopathy, and (3) detecting spatial lesion patterns suggesting somatotopic organization of the BP.

MATERIALS AND METHODS

Thirty-six patients (50.9 ± 12.7 years) with clinical symptoms, nerve conduction studies, and needle electromyography findings suggestive of brachial plexopathy and 36 control subjects matched for age and sex (50.8 ± 12.6 years) underwent high-resolution MRN of the BP. Lesion determination and localization was performed by 2 blinded neuroradiologists at the anatomical levels of the plexus trunks and cords.

RESULTS

By applying defined criteria of structural plexus lesions on high-resolution MRN, all patients were correctly rated as affected, whereas 34 of 36 controls were correctly rated as unaffected by independent and blinded reading from 2 neuroradiologists with overall good to excellent interrater reliability. In all cases, plexopathies with a compressive etiology (n = 12) were correctly distinguished from noncompressive plexopathies with inflammatory origin (n = 24). Pathoanatomical contiguity of lesion from trunk into cord level allowed recognition of distinct somatotopical patterns of fascicular involvement, which correlated closely with the spatial distribution of clinical symptoms and electrophysiological data.

CONCLUSIONS

Brachial plexus MRN is highly accurate for differentiating patients with symptomatic plexopathy from healthy controls and for distinguishing patients with compressive neuropathy and noncompressive plexopathy. Furthermore, BP MRN revealed evidence for somatotopic organization of the BP. Therefore, as an addition to functional information of electrodiagnostic studies, anatomical information gained by BP MRN may help to improve the efficiency and accuracy of patient care.

Magnetic resonance imaging for detecting root avulsions in traumatic adult brachial plexus injuries: protocol for a systematic review of diagnostic accuracy

BACKGROUND

Adult brachial plexus injuries (BPI) are becoming more common. The reconstruction and prognosis of pre-ganglionic injuries (root avulsions) are different to other types of BPI injury. Preoperative magnetic resonance imaging (MRI) is being used to identify root avulsions, but the evidence from studies of its diagnostic accuracy are conflicting. Therefore, a systematic review is needed to address uncertainty about the accuracy of MRI and to guide future research.

METHODS

We will conduct a systematic search of electronic databases alongside reference tracking. We will include studies of adults with traumatic BPI which report the accuracy of preoperative MRI (index test) against surgical exploration of the roots of the brachial plexus (reference standard) for detecting either of the two target conditions (any root avulsion or any pseudomeningocoele as a surrogate marker of root avulsion). We will exclude case reports, articles considering bilateral injuries and studies where the number of true positives, false positives, false negatives and true negatives cannot be derived. The methodological quality of the included studies will be assessed using a tailored version of the QUADAS-2 tool. Where possible, a bivariate model will be used for meta-analysis to obtain summary sensitivities and specificities for both target conditions. We will investigate heterogeneity in the performance of MRI according to field strength and the risk of bias if data permits.

DISCUSSION

This review will summarise the current diagnostic accuracy of MRI for adult BPI, identify shortcomings and gaps in the literature and so help to guide future research.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42016049702 .

The diagnostic accuracy of 1.5T magnetic resonance imaging for detecting root avulsions in traumatic adult brachial plexus injuries

Identification of root avulsions is of critical importance in traumatic brachial plexus injuries because it alters the reconstruction and prognosis. Pre-operative magnetic resonance imaging is gaining popularity, but there is limited and conflicting data on its diagnostic accuracy for root avulsion. This cohort study describes consecutive patients requiring brachial plexus exploration following trauma between 2008 and 2016. The index test was magnetic resonance imaging at 1.5 Tesla and the reference test was operative exploration of the supraclavicular plexus. Complete data from 29 males was available. The diagnostic accuracy of magnetic resonance imaging for root avulsion(s) of C5-T1 was 79%. The diagnostic accuracy of a pseudomeningocoele as a surrogate marker of root avulsion(s) of C5-T1 was 68%. We conclude that pseudomeningocoles were not a reliable sign of root avulsion and magnetic resonance imaging has modest diagnostic accuracy for root avulsions in the context of adult traumatic brachial plexus injuries.

LEVEL OF EVIDENCE

III.

Ultrasound of the Normal Brachial Plexus

Ultrasound (US) allows a reliable examination of the brachial plexus except for the spinal nerve roots, located deep in the neuro-foramina, beyond the shadowing of the transverse processes of the vertebral bodies. All the other fascicles of the brachial plexus can be mapped by US from the roots of the spinal cervical nerves, from C5 to T1 to the branches at level of the axillary region. US can be considered as an alternative to Magnetic Resonance Imaging (MRI) when MRI is contraindicated, not readily available or in case of claustrophobia. US can be used for the assessment of the brachial plexus in case of trauma, tumours and fibrosis induced by radiation oncology treatments. US is also a valuable tool to perform imaging-guided blocks of the brachial plexus. A prerequisite for a reliable US examination of the brachial plexus is knowledge of its complex anatomy. The operator is also required to learn the appropriate US views in order to have an optimal depiction of the brachial plexus, especially the areas where the bone structure's interposition makes the visualisation of the brachial plexus more arduous. The aim of this review is to provide the reader with the basics principles of the US normal anatomy and technique for a reliable mapping of the brachial plexus.

Dynamic CT angiography for the diagnosis of patients with thoracic outlet syndrome: Correlation with patient symptoms

INTRODUCTION

Vasculo-nervous structures serving the upper limbs may be compressed as they pass through three areas: the inter-scalene triangle (IST), the costo-clavicular space (CCS) and the retropectoralis minor space (RMS). The diagnosis of thoracic outlet syndrome (TOS) is essentially clinical, but requires imaging to specify the site of compression, its grade and the existence of predisposing anatomical factors, in order to guide the treatment and eliminate the main differential diagnoses.

MATERIAL AND METHODS

Images from 141 patients who underwent dynamic CT angiography of the thoracic outlets from June 2008 to January 2015 were analyzed retrospectively. Patients had unilateral or bilateral vascular, neurological, mixed or atypical symptoms. We studied the degree of stenosis of the subclavian artery with the following grading system: 1 (0-<25%), 2 (25-<50%), 3 (50-<75%), 4 (75-100%). The site of stenosis and the presence of underlying anatomical predisposing factors were also taken in account.

RESULTS

A total of 221 thoracic outlets were analyzed. Symptoms were neurological, mixed, vascular and atypical in 30%, 28%, 13% and 12%, respectively. Among patients with bilateral acquisitions, 38 outlets were asymptomatic; 40% of symptomatic outlets and only 5% of asymptomatic ones had grade 3 or 4 stenosis. 63% of the stenosis were in the CCS and 37% in the IST; 21% had a predisposing anatomical factor most often a costo-clavicular anomaly, associated with significant stenosis in 50% of cases.

CONCLUSION

Vascular stenosis of more than 50% on dynamic CT angiography is strongly associated with TOS. Predisposing factors were present in 21% of cases, causing significant vascular stenosis in half, underscoring the need for functional evaluation.

Frequency of the Pectoralis Minor Compression Syndrome in Patients Treated for Thoracic Outlet Syndrome

BACKGROUND

Pectoralis minor compression syndrome (PMCS) is a compression of the neurovascular structures in the subpectoral tunnel and remains underestimated in the management of patients with thoracic outlet syndrome (TOS). Its underdiagnosis may be responsible for incomplete or failed treatment. The aim of the study was to evaluate the frequency of PMCS in our experience.

METHODS

We retrospectively reviewed all patients treated for TOS in our department. We selected those in whom PMCS was diagnosed with a systematic dynamic arteriography. Surgery was performed using the Roos axillary approach when a first rib resection was associated or an elective approach when a first rib resection was not associated.

RESULTS

From January 2004 to December 2014, 374 surgeries for TOS were performed in 279 patients, which included 90 men (sex ratio = 0.48) with a mean age of 40.1 ± 10 years old. Among these patients, 63 (22.5%) underwent 82 interventions (21.9%) for PMCS, including 26 men (sex ratio = 0.70, P < 0.05) with a mean age of 37.9 ± 9.4 years old. Tenotomy of the pectoralis minor muscle was performed using axillary approach if it was associated with a first rib resection in 74 cases (90.2%) or through an elective approach in 8 cases (9.8%) if it was isolated. Four (4.9%) postoperative complications were found (1 hematoma [1.2%], 1 hemothorax [1.2%], 1 scapula alata [1.2%], and 1 subclavian vein thrombosis [1.2%]), all after an axillary approach. In 63 cases (79.7%), preoperative symptoms were resolved. In 14 cases (17.7%), symptom resolution was incomplete, and 2 patients (2.6%) had recurrent symptoms.

CONCLUSIONS

Evaluation of PMCS in TOS is justified by its frequency and the simplicity and low morbidity of the surgical procedure.

Description and ultrasound targeting of the origin of the suprascapular nerve

Anatomical variations in the suprascapular nerve (SSN) and its depth in the suprascapular notch can make it difficult to target with ultrasonography (US). One alternative could be a proximal approach to the SSN, if US provides a reliable description of its origin (orSSN). The primary objective of this study was to demonstrate that US can reliably locate the orSSN. The secondary objective was to describe the features of the proximal SSN. Seventy brachial plexuses (BPs) from 30 healthy volunteers (60 BPs) and 5 cadavers (10 BPs) were included. There were two parts to this study: (1) description of the proximal SSN in healthy volunteers using US to determine the diameter, depth and location of the orSSN; (2) targeting of the orSSN with US in cadaver limbs to determine its distance from the needle, ink marking and locating the orSSN. In Part I, the diameter of the orSSN averaged 1.33 mm (1-9 mm) and its depth averaged 5.12 mm (2.7-10.6 mm). The orSSN was located in the upper trunk of the BP (53) or its posterior division (7). In Part II, the orSSN was successfully targeted in nine of the 10 specimens by US; the needle/orSSN distance averaged 3.8 mm (0-8 mm). The implanted needle was at the orSSN in two cases, proximal to it in seven and distal to it in one. US is a valid modality for describing and pinpointing the orSSN, irrespective of patient morphology. Clin. Anat. 30:747-752, 2017. © 2017Wiley Periodicals, Inc.

Sonographic tracking of trunk nerves: essential for ultrasound-guided pain management and research

Delineation of architecture of peripheral nerves can be successfully achieved by high-resolution ultrasound (US), which is essential for US-guided pain management. There are numerous musculoskeletal pain syndromes involving the trunk nerves necessitating US for evaluation and guided interventions. The most common peripheral nerve disorders at the trunk region include thoracic outlet syndrome (brachial plexus), scapular winging (long thoracic nerve), interscapular pain (dorsal scapular nerve), and lumbar facet joint syndrome (medial branches of spinal nerves). Until now, there is no single article systematically summarizing the anatomy, sonographic pictures, and video demonstration of scanning techniques regarding trunk nerves. In this review, the authors have incorporated serial figures of transducer placement, US images, and videos for scanning the nerves in the trunk region and hope this paper helps physicians familiarize themselves with nerve sonoanatomy and further apply this technique for US-guided pain medicine and research.

Brachial metastatic plexopathy as the inaugural manifestation of lung cancer: multimodality imaging

Metastatic infiltration of a peripheral plexus, also named metastatic plexopathy (MP), often results in severe pain and muscular weakness. This rather rare event may have a dramatic impact on the quality of life of patients affected by cancer. We hereby report a rare case of painful MP of the left cervicobrachial plexus presenting as the inaugural manifestation of poorly differentiated large-cell lung carcinoma in a 53-year-old patient. This responsible lung carcinoma was fortuitously diagnosed during MRI of the brachial plexus (BP). Complementary cancer staging was completed by contrast-enhanced multidetector CT, 18-fludeoxyglucose–positron emission tomography/CT and colour Doppler ultrasound of the BP. Although MRI remains the gold standard method for imaging the BP, our reported case emphasizes the alternative diagnostic capabilities of contrast-enhanced multidetector CT and ultrasound and confirms the high specificity of 18-fludeoxyglucose–positron emission tomography/CT in distinguishing brachial MP from secondary radiation plexopathy.

Neurogenic thoracic outlet syndrome: current diagnostic criteria and advances in MRI diagnostics

Neurogenic thoracic outlet syndrome (nTOS) is caused by compression of the brachial plexus as it traverses from the thoracic outlet to the axilla. Diagnosing nTOS can be difficult because of overlap with other complex pain and entrapment syndromes. An nTOS diagnosis is made based on patient history, physical exam, electrodiagnostic studies, and, more recently, interpretation of MR neurograms with tractography. Advances in high-resolution MRI and tractography can confirm an nTOS diagnosis and identify the location of nerve compression, allowing tailored surgical decompression. In this report, the authors review the current diagnostic criteria, present an update on advances in MRI, and provide case examples demonstrating how MR neurography (MRN) can aid in diagnosing nTOS. The authors conclude that improved high-resolution MRN and tractography are valuable tools for identifying the source of nerve compression in patients with nTOS and can augment current diagnostic modalities for this syndrome.

Reference Values for the Scalene Interval Width During Varying Degrees of Glenohumeral Abduction Using Ultrasonography

OBJECTIVE

The aim of this study was to establish reference values for the width of the interval between the anterior and middle scalene muscles using ultrasonography during varying degrees of glenohumeral joint (GH) abduction. Reliability and body mass index (BMI) data were also assessed.

METHODS

Interscalene triangles of asymptomatic participants were scanned bilaterally in the transverse plane. Images were obtained at 0°, 90°, and 150° of GH abduction with the participant seated. Width measurements were taken between the anterior and middle scalene muscle borders by bisecting the C6 nerve root as it passed superficial to the posterior tubercle of the C7 transverse process. Intra- and interexaminer reliability and BMI correlation were studied. Statistical significance was defined as P ≤ .05.

RESULTS

Images of 42 scalene intervals were included from 21 participants (11 female). Mean participant age was 25.3 ± 3.9 years; mean BMI was 25.4 ± 2.7 kg/m². Scalene interval measurements at 0°, 90°, and 150° of GH abduction were 4.5 ± 0.5 mm, 4.6 ± 0.5 mm, and 4.4 ± 0.7 mm, respectively, without a significant difference (P = .07). Intraexaminer reliability was excellent (0°: intraclass correlation coefficient [ICC] = 0.82; 90°: ICC = 0.89; 150°: ICC = 0.90). Interexaminer reliability was good to excellent (0°: ICC = 0.59; 90°: ICC = 0.85; 150°: ICC = 0.89). Body mass index was positively correlated only at 0° of GH abduction.

CONCLUSIONS

This study establishes previously unreported reference ultrasonography values for the width of the scalene interval. Intraexaminer reliability was excellent at all glenohumeral positions, and interexaminer reliability was determined to be good to excellent. Body mass index was positively correlated only at 0° of GH abduction.