US of the Peripheral Nerves of the Upper Extremity: A Landmark Approach

Neuralgic amyotrophy: An update in evaluation, diagnosis, and treatment approaches

Neuralgic amyotrophy (NA) is an underrecognized peripheral nerve disorder distinguished by severe pain followed by weakness in the distribution of one or more nerves, most commonly in the upper extremity. While classically felt to carry a favorable prognosis, updates in research have demonstrated that patients frequently endure delay in diagnosis and continue to experience long term pain, paresis, and fatigue even years after the diagnosis is made. A transition in therapeutic approach is recommended and described by this review, which emphasizes the necessity to target compensatory abnormal motor control and fatigue by focusing on motor coordination, energy conservation strategies, and behavioral change, rather than strength training which may worsen the symptoms. The development of structural hourglass-like constrictions (HGCs) on imaging can help confirm the suspected clinical diagnosis, and in association with persistent weakness and limited recovery on electrodiagnostic testing may be considered for surgical consultation. Given the complex nature of management, a multidisciplinary approach is described, which can provide an optimal level of care and support for patients with persistent symptoms from NA and allow more unified guidance of rehabilitation and surgical referrals.

Diagnostic Musculoskeletal Ultrasound in the Evaluation of the Median Nerve

The median nerve is a crucial structure in the forearm and wrist, responsible for motor and sensory functions. Accurate diagnosis of nerve injury is essential for appropriate treatment planning and optimizing patient outcomes. Although magnetic resonance imaging (MRI) and nerve conduction studies (NCS) are the gold standard for nerve assessment, diagnostic musculoskeletal (MSK) ultrasound offers a portable, real-time, and cost-effective alternative that is gaining traction in rehabilitation and sports medicine settings. MSK ultrasound has emerged as a valuable, non-invasive imaging modality for evaluating median nerve pathology, including carpal tunnel syndrome (CTS), nerve entrapment, and traumatic nerve injuries. This article reviews the utility of MSK ultrasound in evaluating the median nerve injury, including its anatomy, common injury patterns, sonographic techniques, and clinical implications for professional rehabilitation. By integrating MSK ultrasound into clinical practice, providers can improve the accuracy of diagnosis, monitor healing progression, and guide rehabilitation strategies for optimal patient outcomes.

The Role of Ultrasound in the Diagnosis of Intraneural Perineurioma

INTRODUCTION/AIMS

Reports on imaging-based diagnosis of intraneural perineurioma remain limited. This study aimed to summarize the role of ultrasound in diagnosing intraneural perineuriomas to enhance clinical awareness and diagnostic accuracy among clinicians and ultrasonographers.

METHODS

A retrospective study was conducted on 11 patients diagnosed with intraneural perineurioma through surgery or biopsy at our hospital between June 2015 and June 2022. All patients underwent ultrasonography, and their ultrasonographic characteristics were analyzed.

RESULTS

All patients presented with isolated mononeuropathy. Sonography revealed fusiform enlargement of the affected nerve. The length of the lesion ranged from 1.5 to 20.0 (5.2 ± 5.4) cm. The intraneural perineuriomas were hypoechoic relative to skeletal muscle. The internal homogeneity was heterogeneous, without posterior acoustic enhancement. The lesion was centrally located within the nerve. The inner epineurium was blurred with a continuous fascicular structure. Two patients had hyperechoic calcifications with posterior acoustic shadows in their lesions. Vascularization assessment using color or power Doppler imaging revealed blood flow in all the tumors. The cross-sectional area of the affected nerves was at least twice as large as that of the contralateral side, with some patients exhibiting up to an eight-fold increase.

DISCUSSION

High-frequency ultrasonography provides important evidence for the clinical diagnosis of intraneural perineurioma. When combined with magnetic resonance imaging and electrophysiological studies, ultrasound can aid in clinical decision-making and facilitate long-term monitoring. Given its accessibility and diagnostic potential, ultrasonography can be one of the preferred imaging examinations for evaluating intraneural perineuriomas.

The Role of 70-MHz Ultrahigh-Frequency Ultrasound in the Peripheral Nerve Injury

AIM

High-frequency ultrasound with an 18-MHz probe (18 MHz-HFUS) plays a relevant role in the evaluation of peripheral nerve injury (PNI). Ultrahigh-frequency ultrasound with a 70-MHz probe (70 MHz-UHFUS) offers higher spatial resolution and could allow a better detection of PNI. This study aimed to compare the diagnostic performance of HFUS and UHFUS in PNI detection.

MATERIALS AND METHODS

In this retrospective study, were selected, between July 2022 and April 2024, 61 patients underwent HFUS, UHFUS, and nerve conduction study (NCS) for clinical suspicion of traumatic forearm PNI. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy of HFUS and UHFUS in PNI detection were calculated and compared. NCS was used as the reference standard. Nonparametric statistical tests were used. A p value of < 0.05 was considered statistically significant.

RESULTS

Comparing the diagnostic performance in PNI detection, the 70 MHz-UHFUS showed a sensitivity and diagnostic accuracy significantly higher than 18 MHz-HFUS, respectively, 98.0% versus 82.4% (p = 0.0205) and 95.1% versus 82.0% (p = 0.0468). Otherwise, not significantly difference were in specificity, PPV, and NPV.

CONCLUSIONS

UHFUS compared to HFUS demonstrated a higher sensitivity and diagnostic accuracy in PNI detection.

Ultrasound of the Median Nerve: A Pictorial Review. Normal Ultrasound Findings and Variations

This is the first of a two-part article in which we focus on the Ultrasound (US) appearance of the normal median nerve (MN) and its main branches. The detailed anatomy and US anatomy of the MN course are presented with high-resolution images obtained with the latest-generation US machines and transducers. Variations are discussed to avoid misinterpretation of normal findings.

Anatomical validation of the sonographic detection of small nervous structures

INTRODUCTION

Ultrasound is a primary imaging modality for diagnosing and managing nerve-related injuries, particularly for identifying peripheral nerve locations. However, its accuracy and reliability in surgical applications remain insufficiently explored, potentially limiting its utility in nerve surgery.

PURPOSE

This study aims to assess the precision of ultrasound in identifying upper limb peripheral nerves by comparing ultrasonographic findings with direct human cadaveric dissection.

METHOD

Fourteen fresh-frozen upper limb specimens were examined in February 2023. Ultrasound assessments were performed by two experienced musculoskeletal radiologists using three linear probes (15 MHz, 24 MHz, and a 22 MHz hockey stick probe). Seven peripheral nerves were identified and marked using dye injections. Subsequent dissections were conducted under loupe magnification by hand surgeons.

RESULT

The recurrent motor branch of the median nerve exhibited the lowest discrepancy (mean 1.014 ± 1.459 mm) and the highest accuracy (64.29% of specimens). The greatest discrepancy was observed in the branch of the musculocutaneous nerve to the brachialis (mean 5.114 ± 3.758 mm). The interrater correlation coefficient (ICC) varied across nerve sites, ranging from - 6.298 to 0.795, with the highest ICC observed in the superficial branch of the ulnar nerve (0.795, 0.066).

CONCLUSION

These findings suggest that ultrasound is a valid and effective tool for identifying peripheral nerve branches in the upper limb, particularly for superficial nerves. Improved accuracy in ultrasound-guided nerve identification may enhance surgical precision and reduce complications in nerve-related procedures.

Imaging of elbow entrapment neuropathies

Entrapment neuropathies at the elbow are common in clinical practice and require an accurate diagnosis for effective management. Understanding the imaging characteristics of these conditions is essential for confirming diagnoses and identifying underlying causes. Ultrasound serves as the primary imaging modality for evaluating nerve structure and movement, while MRI is superior for detecting muscle denervation. Plain radiography and CT play a minor role and can be used for the evaluation of bony structures and calcifications/ossifications. Comprehensive knowledge of anatomical landmarks, nerve pathways, and compression sites is crucial for clinicians to accurately interpret imaging and guide appropriate treatment strategies for entrapments of ulnar, median, and radial nerves, and their branches. CRITICAL RELEVANCE STATEMENT: Accurate imaging and anatomical knowledge are essential for diagnosing elbow entrapment neuropathies. Ultrasound is the preferred modality for assessing nerve structure and motion, while MRI excels in detecting muscle denervation and guiding effective management of ulnar, median, and radial nerve entrapments. KEY POINTS: Ultrasound is the primary modality for assessing nerve structure and stability. Findings include nerve structural loss, isoechogenicity, thickening, and hyper-vascularization. MRI provides a comprehensive evaluation of the elbow and accurate muscle assessment. Imaging allows the identification of compressive causes, including anatomical variants, masses, or osseous anomalies. Awareness of anatomical landmarks, nerve pathways, and compression sites is essential.

Proximal median nerve neuropathy: electrodiagnostic and ultrasound findings in 62 patients

Objectives

Proximal median nerve (PMN) neuropathies are caused by lesions proximal to the carpal tunnel, which include the forearm, elbow, upper arm, and brachial plexus. Differentiating between carpal tunnel syndrome and PMN neuropathies is important to guide management and is based on clinical, electrodiagnostic (EDX), and ultrasound (US) findings. This study describes the clinical, EDX, and US features in 62 patients with PMNs.

Methods

All patients underwent EDX studies, and 52 (83.9%) had a US study. The patients were assigned to one of the following four localization zones of PMN neuropathies based on clinical and EDX criteria: Zone 1: extends from the fascicles in the brachial plexus contributing to the median nerve to the innervation of the pronator teres (PT); Zone 2: distal to the branch to the PT and proximal to the origin of the anterior interosseous nerve (AIN); Zone 3: involves the origin of the AIN; and Zone 4: distal to the origin of the AIN and proximal to the carpal tunnel. The localization was based on the pattern of muscle weakness, topography of EMG abnormalities, and US study findings.

Results

The anatomical locations of the PMN neuropathies based on clinical, EDX, and US findings were as follows: Zone 1 in 38 patients (61.3%), Zone 2 in 6 patients (9.7%), Zone 3 in 7 patients (11.3%), and Zone 4 in 11 patients (17.7%). The most common etiology among all 62 patients was iatrogenic injury (30 [48.4%]), followed by non-iatrogenic trauma (20 [32.2%]). The following EDX findings were noted: prolonged distal motor latency (29 [46.8%]), decreased motor nerve conduction velocity in the forearm (22 [35.5%]), low amplitude or absent compound muscle action potentials (50 [80.6%]), and abnormal or absent sensory nerve action potentials (50 [80.6%]). Of the 52 (83.9%) patients who underwent US studies, a total of 22 (42.3%) patients showed an increased cross-sectional area of the median nerve. A neuroma was observed in 9 patients (17.4%).

Conclusion

It is often possible to localize the site of the median nerve involvement and gain insight into the underlying cause based on clinical and EMG findings, but in certain cases, a US study may be necessary to confirm the location.

High-resolution Ultrasound of Peripheral Nerve Disorders

Peripheral nerve disorders refer to any condition that damages the peripheral nervous system with variable presentations and numerous causes. The diagnosis is usually suspected clinically and then confirmed using electrophysiology. Yet electrodiagnostic studies lack precise anatomical delineation and often cannot determine the underlying cause of the peripheral neuropathy. However, thanks to recent technological advances, high-resolution ultrasound (HRUS) and magnetic resonance (MR) imaging have emerged as exceptional modalities to identify the exact site of pathology and demonstrate the underlying etiology. These developments have led to a multimodality approach to peripheral nerve disorders. Imaging provides anatomical and morphological information while functional evaluation remains derived from electrodiagnostic study. This article reviews the HRUS features of common as well as less frequent peripheral nerve disorders: entrapment neuropathies, traumatic injuries, neuralgic amyotrophy, polyneuropathies, and nerve tumors.

High-frequency ultrasound imaging findings in the diagnosis of segmental schwannomatosis of the ulnar nerve: case report and literature review

Schwannomatosis is characterized by the development of multiple schwannomas without evidence of vestibular tumors. Segmental schwannomatosis is defined as being limited to one limb or five or fewer contiguous segments of the spine. We report a case of a 20-year-old male with the painful masses of the left upper extremity with associated numbness and paresthesia in the ulnar nerve distribution. The high-frequency ultrasound showed that the ulnar nerve fascicles were enlarged and expanded with beadlike growth. The patient underwent surgery twice and all the tumors were pathologically confirmed to be schwannomas. Together, the medical history, imaging, and pathology findings indicated the diagnosis of segmental schwannomatosis. By the imaging diagnostic tools, MRI is the most commonly used in assistance with diagnosis of segmental schwannomatosis while high-frequency ultrasonography is rare. In this paper, we discuss the value of high-frequency ultrasonography in the diagnosis of this rare disease. This case report provides a deeper understanding of segmental schwannomatosis and may help improve the accuracy of preoperative diagnosis.

Anatomical and Micro-CT measurement analysis of ocular volume and intraocular volume in adult Bama Miniature pigs, New Zealand rabbits, and Sprague-Dawley rats

AIM

Utilizing a combination of micro-computed tomography (micro-CT) and anatomical techniques for the volumetric assessment of the eyeball and its constituents in Bama Miniature Pigs, New Zealand rabbits, and Sprague-Dawley(SD) rats.

METHOD

Six Bama Miniature pigs, New Zealand rabbits, and SD rats were enrolled in the study. Micro-CT and gross volumetric estimation of ocular volume were employed to acquire data on ocular volume, anterior chamber volume, lens volume, and vitreous cavity volume for each eye.

RESULTS

The eyeball volume of pigs ranges from approximately 5.36 ± 0.27 to 5.55 ± 0.28 ml, the lens volume from approximately 0.33 ± 0.02 to 0.37 ± 0.06 ml, the anterior chamber volume from approximately 0.19 ± 0.05 to 0.28 ± 0.04 ml, and the vitreous volume is approximately 3.20 ± 0.18 ml. For rabbits, the eye volume, lens volume, anterior chamber volume, and vitreous volume range from approximately 3.02 ± 0.24 to 3.04 ± 0.24 ml, 0.41 ± 0.02 to 0.44 ± 0.02 ml, 0.23 ± 0.04 to 0.26 ± 0.05 ml, and 1.54 ± 0.14 ml, respectively. In SD rats, the volumes are 0.14 ± 0.02 to 0.15 ± 0.01 ml for the eyeball, 0.03 ± 0.00 to 0.03 ± 0.00 ml for the lens, 0.01 ± 0.00 to 0.01 ± 0.01 ml for the anterior chamber, and 0.04 ± 0.01 ml for the vitreous volume.

CONCLUSION

The integration of micro-CT and gross volumetric estimation of ocular volume proves effective in determining the eyeball volume in Bama Miniature Pigs, New Zealand rabbits, and SD rats. Understanding the volume distinctions within the eyeballs and their components among these experimental animals can lay the groundwork for ophthalmology-related drug research.

Diagnostic Capability of Ultrasonography in Evaluating Peripheral Nerve Injuries of the Brachial Plexus

BACKGROUND

The purpose of this study is to determine the diagnostic capability of ultrasonography (US) in patients with suspected brachial plexus injury (BPI) to the terminal nerves by comparing physical examination (PE) findings with US, electromyography (EMG), and magnetic resonance imaging (MRI) reports.

METHODS

All patients at a single institution who underwent US for peripheral nerve injury of the brachial plexus and terminal nerves resulting in sensory-motor deficits from October 1, 2017 to October 31, 2023 were identified. A retrospective chart review was performed. Each PE, US, EMG, and MRI reports were given an overall rating: "normal" or "abnormal." Terminal nerves (musculocutaneous, axillary, radial, ulnar, medial) were individually assessed as "normal" or "abnormal." The interobserver agreement between reports was calculated using Cohen kappa. Specificity and sensitivity analyses were performed to determine diagnostic accuracy and were reported with 95% confidence intervals (CI).

RESULTS

A total of 120 patients were included. Most injuries were traumatic in nature (78.8%) and were low-energy (53.8%). When each imaging modality was compared with the PE findings, EMG had the highest interobserver agreement (Cohen kappa = 0.18), followed by US (Cohen kappa = 0.10), and last MRI (Cohen kappa = 0.07). The US had the highest sensitivity (0.92, CI = 0.85, 0.96) among the 3 imaging modalities (Table 2). On US, the ulnar nerve was most commonly abnormal (n = 84, 70.0%).

DISCUSSION

Ultrasonography serves as a useful adjunct in the workup of patients with suspected peripheral BPI and is reliable in localizing the pathology of injured terminal nerves in the brachial plexus.

Pronator syndrome and anterior interosseous nerve palsy due to neurolymphomatosis: a case report

Pronator syndrome is a median nerve entrapment neuropathy that can be difficult to diagnose due to its variable presentation and objective findings. Neurolymphomatosis is an uncommon disease in which malignant lymphocytes infiltrate central or peripheral nerve endoneurium and is often missed for prolonged periods prior to diagnosis. We present a rare case of pronator syndrome and anterior interosseous nerve palsy due to neurolymphomatosis that was occult on initial MRI in spite of the presence of a median nerve mass discovered intra-operatively during neurolysis. This case demonstrates the value of ultrasound for the examination of peripheral nerve pathology and illustrates its utility as an adjunct to MRI, in part due to the ability to screen a large region.

Nerve entrapment syndromes of the lower limb: a pictorial review

Peripheral nerves of the lower limb may become entrapped at various points during their anatomical course. While clinical assessment and nerve conduction studies are the mainstay of diagnosis, there are multiple imaging options, specifically ultrasound and magnetic resonance imaging (MRI), which offer important information about the potential cause and location of nerve entrapment that can help guide management. This article overviews the anatomical course of various lower limb nerves, including the sciatic nerve, tibial nerve, medial plantar nerve, lateral plantar nerve, digital nerves, common peroneal nerve, deep peroneal nerve, superficial peroneal nerve, sural nerve, obturator nerve, lateral femoral cutaneous nerve and femoral nerve. The common locations and causes of entrapments for each of the nerves are explained. Common ultrasound and MRI findings of nerve entrapments, direct and indirect, are described, and various examples of the more commonly observed cases of lower limb nerve entrapments are provided.Critical relevance statement This article describes the common sites of lower limb nerve entrapments and their imaging features. It equips radiologists with the knowledge needed to approach the assessment of entrapment neuropathies, which are a critically important cause of pain and functional impairment.Key points• Ultrasound and MRI are commonly used to investigate nerve entrapment syndromes.• Ultrasound findings include nerve hypo-echogenicity, calibre changes and the sonographic Tinel's sign.• MRI findings include increased nerve T2 signal, muscle atrophy and denervation oedema.• Imaging can reveal causative lesions, including scarring, masses and anatomical variants.

Magnetic resonance neurography techniques in the pediatric population

The use of magnetic resonance imaging (MRI) in the evaluation of the central extracranial nervous system, namely the brachial and lumbosacral plexuses, is well established and has been performed for many years. Only recently after numerous advances in MRI, has image quality been sufficient to properly visualize small structures, such as nerves in the extremities. Despite the advances, peripheral MR Neurography remains a complex and difficult examination to perform, especially in the pediatric patient population, in which the risk for motion artifact and compliance is always of concern. Thus, technical aspects of the MR imaging protocol must be flexible but robust, to balance image quality with scan time, in a patient population of varying sizes. An additional important step for reliably performing a successful MR Neurography examination is the non-technical pre-imaging preparation, which includes patient/family education and open communication with referring teams. This paper will discuss in detail the individual technical and non-technical/operational aspects of peripheral MR Neurography, to help guide in building a successful program in the pediatric population.

Deep branch of the radial nerve: effect of pronation/supination on longitudinal nerve alignment

OBJECTIVE

To evaluate the effect of maximal pronation and supination of the forearm on the alignment and anatomic relationship of the deep branch of the radial nerve (DBRN) at the superior arcade of the supinator muscle (SASM) by using high-resolution ultrasound (HRUS).

MATERIALS AND METHODS

In this cross-sectional study, HRUS in the long axis of the DBRN was performed in asymptomatic participants enrolled from March to August 2021. DBRN alignment was evaluated by measuring angles of the nerve in maximal pronation and maximal supination of the forearm independently by two musculoskeletal radiologists. Forearm range of motion and biometric measurements were recorded. Student t, Shapiro-Wilk, Pearson correlation, reliability analyses, and Kruskal-Wallis test were used.

RESULTS

The study population included 110 nerves from 55 asymptomatic participants (median age, 37.0 years; age range, 16-63 years; 29 [52.7%] women). There was a statistically significant difference between the DBRN angle in maximal supination and maximal pronation (Reader 1: 95% CI: 5.74, 8.21, p < 0.001, and Reader 2: 95% CI: 5.82, 8.37, p < 0.001). The mean difference between the angles in maximal supination and maximal pronation was approximately 7° for both readers. ICC was very good for intraobserver agreement (Reader1: r ≥ 0.92, p < 0.001; Reader 2: r ≥ 0.93, p < 0.001), as well as for interobserver agreement (phase 1: r ≥ 0.87, p < 0.001; phase 2: r ≥ 0.90, p < 0.001).

CONCLUSION

The extremes of the rotational movement of the forearm affect the longitudinal morphology and anatomic relationships of the DBRN, primarily demonstrating the convergence of the nerve towards the SASM in maximal pronation and divergence in maximal supination.

Spontaneous radial nerve palsy with hourglass-like constriction

Hourglass-like constriction (HLC) is an uncommon spontaneous mononeuropathy that is typically characterised by a sudden onset of pain followed by palsy, affecting branches of the radial (posterior interosseous nerve) and median nerves (anterior interosseous nerve). HLC of the radial nerve (RN) is rare, with only a few reported cases. Here, we report a case of a man who presented with acute wrist and finger drop due to the HLC of the RN. Surgery was recommended 5 months after clinical observation, when the lesion was resected and primarily repaired, resulting in satisfactory recovery. There is still much that remains unknown about HLC, especially for RN. The current understanding points out an inflammatory disease that should be treated conservatively for 3-7 months. The surgical technique depends mostly on the severity and extent of constriction; however, considering only RN constrictions, primary repair by neurorrhaphy or nerve grafts resulted in better functional outcomes.

Ultra-High-Frequency Ultrasound: A Modern Diagnostic Technique for Studying Melanoma

The development of new ultra-high-frequency devices with a resolution of 30 μm makes it possible to use ultrasound in the study of new small anatomical units and to apply this tool to new fields of pathology. Cutaneous melanoma is a severe skin disease with an incidence of approximately 160 000 new cases each year and 48 000 deaths. In this paper, we evaluate the role of HFUS in the diagnosis of cutaneous melanoma, describe the sonographic appearance of skin layers in the pre-excision phase as well as of lesion features, and correlate the characteristics with pathological examination.

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.

Peripheral Nerve Imaging

Magnetic resonance (MR) neurography and high-resolution ultrasound are complementary modalities for imaging peripheral nerves. Advances in imaging technology and optimized techniques allow for detailed assessment of nerve anatomy and nerve pathologic condition. Diagnostic accuracy of imaging modalities likely reflects local expertise and availability of the latest imaging technology.

Repeatability, Reproducibility and Sources of Variability in the Assessment of Backscatter Coefficient and Texture Parameters from High-Frequency Ultrasound Acquisitions in Human Median Nerve

Ultrasound (US) is an increasingly prevalent and effective diagnostic modality for neuromuscular imaging. Gray-scale B-mode imaging has been the dominant US approach to evaluating nerves qualitatively or making morphometric measurements of nerves, providing important insights into pathological changes for conditions such as carpal tunnel syndrome. Among more recent ultrasound strategies, high-frequency ultrasound (often defined as >15 MHz for clinical applications), quantitative ultrasound and image textural analysis offer promising enhancements for improved and more objective approaches to nerve imaging. In this study, we evaluated the repeatability and reproducibility of backscatter coefficient (BSC) and imaging texture features extracted by gray-level co-occurrence matrices (GLCMs) in homogeneous tissue-mimicking reference phantoms and in median nerves in the wrists of healthy participants. We also investigated several practical sources of variability in the assessment of quantitative parameters, including influences of operators, and participant-to-participant variability. Overall, BSC- and GLCM-based outcomes are highly repeatable and reproducible after operator training, based on measurement of descriptive statistics, repeatability coefficient (RC) and reproducibility coefficient recommended by Quantitative Imaging Biomarker Alliance (QIBA RDC). GLCM parameters appear more reproducible and repeatable than BSC-based parameters in healthy participants in vivo. However, such variability noted here must be compared with the value ranges and variability of the results in pathological nerves, including median nerves afflicted by trauma, overuse syndromes such as carpal tunnel syndrome and after surgical repair.

A standardized ultrasound approach in neuralgic amyotrophy

Neuralgic amyotrophy (NA), also referred to as idiopathic brachial plexitis and Parsonage-Turner syndrome, is a peripheral nerve disorder characterized by acute severe shoulder pain followed by progressive upper limb weakness and muscle atrophy. While NA is incompletely understood and often difficult to diagnose, early recognition may prevent unnecessary tests and interventions and, in some situations, allow for prompt treatment, which can potentially minimize adverse long-term sequalae. High-resolution ultrasound (HRUS) has become a valuable tool in the diagnosis and evaluation of NA. Pathologic HRUS findings can be grouped into four categories: nerve swelling, swelling with incomplete constriction, swelling with complete constriction, and fascicular entwinement, which may represent a continuum of pathologic processes. Certain ultrasound findings may help predict the likelihood of spontaneous recovery with conservative management versus the need for surgical intervention. We recommend relying heavily on history and physical examination to determine which nerves are clinically affected and should therefore be assessed by HRUS. The nerves most frequently affected by NA are the suprascapular, long thoracic, median and anterior interosseous nerve (AIN) branch, radial and posterior interosseous nerve (PIN) branch, axillary, spinal accessory, and musculocutaneous. When distal upper limb nerves are affected (AIN, PIN, superficial radial nerve), the lesion is almost always located in their respective fascicles within the parent nerve, proximal to its branching point. The purpose of this review is to describe a reproducible, standardized, ultrasonographic approach for evaluating suspected NA, and to share reliable techniques and clinical considerations when imaging commonly affected nerves.

US for Traumatic Nerve Injury, Entrapment Neuropathy, and Imaging-guided Perineural Injection

US is commonly performed to help diagnose traumatic peripheral nerve injury and entrapment neuropathy, particularly with superficial nerves, where higher spatial resolution provides an advantage over MRI. Other advantages of US include dynamic evaluation, easy contralateral comparison, fewer implant contraindications, less artifact from ferromagnetic debris, and facile needle guidance for perineural injections. The authors review peripheral nerve US for traumatic peripheral nerve injury with an emphasis on injury grading and entrapment neuropathy and describe best-practice techniques for US-guided perineural injections while highlighting specific techniques and indications. Online supplemental material is available for this article. ^©RSNA, 2022.

Nerve Imaging in the Wrist

Neuropathic symptoms involving the wrist are a common clinical presentation that can be due to a variety of causes. Imaging plays a key role in differentiating distal nerve lesions in the wrist from more proximal nerve abnormalities such as a cervical radiculopathy or brachial plexopathy. Imaging complements electrodiagnostic testing by helping define the specific lesion site and by providing anatomical information to guide surgical planning. This article reviews nerve anatomy, normal and abnormal findings on ultrasonography and magnetic resonance imaging, and common and uncommon causes of neuropathy.

Quantifying the Elasticity Properties of the Median Nerve during the Upper Limb Neurodynamic Test 1

Background

The upper limb neurodynamic test 1 (ULNT1) consists of a series of movements that are thought to detect an increase in neuromechanical sensitivity. In vivo, no trail was made to quantify the association between the nerve elasticity and different limb postures during ULNT1.

Objectives

(1) To investigate the relationship between nerve elasticity and limb postures during ULNT1 and (2) to investigate the intra- and interoperator reliabilities of shear wave elastography (SWE) in quantifying the elasticity of median nerve.

Methods

Twenty healthy subjects (mean age: 19.9 ± 1.4 years old) participated in this study. The median nerve was imaged during elbow extension in the following postures: (1) with neutral posture, (2) with wrist extension (WE), (3) with contralateral cervical flexion (CCF), and (4) with both WE and CCF. The intra- and interoperator reliabilities measured by two operators at NP and CCF+WE and intraclass correlation coefficients (ICCs) were calculated.

Results

The intraoperator (ICC = 0.72–0.75) and interoperator (ICC = 0.89–0.94) reliabilities for measuring the elasticity of the median nerve ranged from good to excellent. The mean shear modulus of the median nerve increased by 53.68% from NP to WE+CCF.

Conclusion

SWE is a reliable tool to quantify the elasticity of the median nerve. There was acute modulation in the elasticity of the median nerve during the ULNT1 when healthy participants reported substantial discomfort. Further studies need to focus on the elasticity properties of the median nerve in patients with peripheral neuropathic pain.

Diaphragm and Phrenic Nerve Ultrasound in COVID-19 Patients and Beyond: Imaging Technique, Findings, and Clinical Applications

The diaphragm, the principle muscle of inspiration, is an under-recognized contributor to respiratory disease. Dysfunction of the diaphragm can occur secondary to lung disease, prolonged ventilation, phrenic nerve injury, neuromuscular disease, and central nervous system pathology. In light of the global pandemic of coronavirus disease 2019 (COVID-19), there has been growing interest in the utility of ultrasound for evaluation of respiratory symptoms including lung and diaphragm sonography. Diaphragm ultrasound can be utilized to diagnose diaphragm dysfunction, assess severity of dysfunction, and monitor disease progression. This article reviews diaphragm and phrenic nerve ultrasound and describes clinical applications in the context of COVID-19.

The EFSUMB Guidelines and Recommendations for Musculoskeletal Ultrasound - Part I: Extraarticular Pathologies

The first part of the guidelines and recommendations for musculoskeletal ultrasound, produced under the auspices of the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB), provides information about the use of musculoskeletal ultrasound for assessing extraarticular structures (muscles, tendons, entheses, ligaments, bones, bursae, fasciae, nerves, skin, subcutaneous tissues, and nails) and their pathologies. Clinical applications, practical points, limitations, and artifacts are described and discussed for every structure. After an extensive literature review, the recommendations have been developed according to the Oxford Centre for Evidence-based Medicine and GRADE criteria and the consensus level was established through a Delphi process. The document is intended to guide clinical users in their daily practice.

Gluteal Contractions as a Gateway to Sacral Plexus

Background

Neurostimulation-guided sacral plexus blocks (SPBs) are primarily indicated for surgeries of the foot and ankle and secondarily for supplementing a lumbar plexus block for hip surgeries. Although ultrasound has largely replaced neurostimulation-guided SPB, it may not be available at all facilities. Hence, it is prudent to understand the intricacies of neurostimulation-guided SPB.

Methodology

In this study, 10 American Society of Anesthesiologists-physical status I and II patients undergoing an intramedullary femoral nail procedure for femoral fractures of the shaft femur received a combined lumbar and sacral plexus block for operative surgery and postoperative pain relief. Neurostimulation-guided SPB was administered in all patients after the lumbar plexus block.

Results

In all patients, gluteal contractions were observed as the stimulating needle advanced during neurostimulation-guided SPB, which was either a dorsal or plantar flexion. The end-point of neurostimulation-guided SPB was obtained at 1-1.5 mm beyond the gluteal contractions.

Conclusions

It is important to understand that gluteal contractions are evident as the needle is advanced and can be considered a gateway during a neurostimulation-guided SPB.

Anatomy of the nerves, vessels, and muscular compartments of the forearm, as revealed by high-resolution ultrasound. Part 2: vascularization of compartments and cutaneous innervation

In recent decades, high-resolution ultrasound (HRUS) has revolutionized the morphological and structural evaluation of peripheral nerves and muscles, revealing details of the internal structure of the neural fascicles and muscle architecture. Applications range from diagnostics to interventional procedures. The anatomy of the forearm region is complex, with several muscles and an extensive network of vessels and nerves. To guarantee the success of the evaluation by HRUS, knowledge of the normal anatomy of the region is essential. The aim of these two companion articles is to present the normal anatomy of the nerves and compartments of the forearm, as revealed by HRUS, as well as the relationships between the main vessels and nerves of the region. Part 1 aims to review the overall structure of nerves, muscles and tendons, as seen on HRUS, and that of the forearm compartments. We present a practical approach, with general guidelines and tips on how best to perform the study. Part 2 is a pictorial essay about compartment vascularization and cutaneous innervation. The relationships between arteries, satellite veins and nerves, as well as the relationship between cutaneous nerves and superficial veins, are demonstrated. Knowledge of the normal anatomy of the forearm improves the technical quality of the examinations, contributing to better diagnoses, as well as improving the performance and safety of interventional procedures.

Anatomy of the nerves, vessels, and muscular compartments of the forearm, as revealed by high-resolution ultrasound. Part 1: overall structure and forearm compartments

In recent decades, high-resolution ultrasound (HRUS) has revolutionized the morphological and structural evaluation of peripheral nerves and muscles, revealing details of the internal structure of the neural fascicles and muscle architecture. Applications range from diagnostics to interventional procedures. The anatomy of the forearm region is complex, with several muscles and an extensive network of vessels and nerves. To guarantee the success of the evaluation by HRUS, knowledge of the normal anatomy of the region is essential. The aim of these two companion articles is to present the normal anatomy of the nerves and compartments of the forearm, as revealed by HRUS, as well as the relationships between the main vessels and nerves of the region. Part 1 aims to review the overall structure of nerves, muscles and tendons, as seen on HRUS, and that of the forearm compartments. We present a practical approach, with general guidelines and tips on how best to perform the study. Part 2 is a pictorial essay about compartment vascularization and cutaneous innervation. Knowledge of the normal anatomy of the forearm improves the technical quality of the examinations, contributing to better diagnoses, as well as improving the performance and safety of interventional procedures.

Ultrasound of the Radial Nerve: A Pictorial Review

This pictorial review focuses on the ultrasound (US) appearance of the normal and pathological radial nerve (RN) and its branches and provides tips with which to locate them and avoid misinterpretation of normal findings. A wide range of our pathological cases are reviewed and presented to help in familiarizing the reader with common and uncommon clinical scenarios that affect the RN and its main branches.

Ultrasonographic evaluation of the median nerve: normal and variant anatomy and appearance

The median nerve is a mixed sensory and motor nerve that innervates part of the flexor muscles in the anterior compartment of the forearm and muscles in the lateral part of the hand; palmar cutaneous and digital cutaneous nerves branch from the median nerve, which provides sensory innervation to the skin on the radial side of the palm. Also, the median nerve is an object of interest because neuropathy of the median nerve at the level of the carpal tunnel is the most common entrapment neuropathy which increases dramatically in patients with diabetes. Neuromuscular ultrasound provides extensive diagnostic information and has proved itself as a useful complementary test to electrodiagnostic examinations in cases involving median nerve neuropathy. It often happens that the cause of nerve entrapment and neuropathy are variants of several anatomical structures along the course of the median nerve. It is important to be aware and report such anatomical variations of the median nerve in order to avoid damaging the nerve during surgical treatment. Despite the frequently documented abnormalities in the pathway of the brachial plexus and the median nerve, the anatomical variations are unusual to see and are rarely reported. Moreover, there are variations that do not fit under any of the classifications described in the literature.

In vivo Visualization of Pig Vagus Nerve "Vagotopy" Using Ultrasound

Background: Placement of the clinical vagus nerve stimulating cuff is a standard surgical procedure based on anatomical landmarks, with limited patient specificity in terms of fascicular organization or vagal anatomy. As such, the therapeutic effects are generally limited by unwanted side effects of neck muscle contractions, demonstrated by previous studies to result from stimulation of (1) motor fibers near the cuff in the superior laryngeal and (2) motor fibers within the cuff projecting to the recurrent laryngeal. Objective: Conventional non-invasive ultrasound, where the transducer is placed on the surface of the skin, has been previously used to visualize the vagus with respect to other landmarks such as the carotid and internal jugular vein. However, it lacks sufficient resolution to provide details about the vagus fascicular organization, or detail about smaller neural structures such as the recurrent and superior laryngeal branch responsible for therapy limiting side effects. Here, we characterize the use of ultrasound with the transducer placed in the surgical pocket to improve resolution without adding significant additional risk to the surgical procedure in the pig model. Methods: Ultrasound images were obtained from a point of known functional organization at the nodose ganglia to the point of placement of stimulating electrodes within the surgical window. Naïve volunteers with minimal training were then asked to use these ultrasound videos to trace afferent groupings of fascicles from the nodose to their location within the surgical window where a stimulating cuff would normally be placed. Volunteers were asked to select a location for epineural electrode placement away from the fascicles containing efferent motor nerves responsible for therapy limiting side effects. 2-D and 3-D reconstructions of the ultrasound were directly compared to post-mortem histology in the same animals. Results: High-resolution ultrasound from the surgical pocket enabled 2-D and 3-D reconstruction of the cervical vagus and surrounding structures that accurately depicted the functional vagotopy of the pig vagus nerve as confirmed via histology. Although resolution was not sufficient to match specific fascicles between ultrasound and histology 1 to 1, it was sufficient to trace fascicle groupings from a point of known functional organization at the nodose ganglia to their locations within the surgical window at stimulating electrode placement. Naïve volunteers were able place an electrode proximal to the sensory afferent grouping of fascicles and away from the motor nerve efferent grouping of fascicles in each subject (n = 3). Conclusion: The surgical pocket itself provides a unique opportunity to obtain higher resolution ultrasound images of neural targets responsible for intended therapeutic effect and limiting off-target effects. We demonstrate the increase in resolution is sufficient to aid patient-specific electrode placement to optimize outcomes. This simple technique could be easily adopted for multiple neuromodulation targets to better understand how patient specific anatomy impacts functional outcomes.

Echoentomography for Assessing Braconid Parasitization on Soft-Bodied Tephritid Hosts

Entomological approaches currently available for assessing host parasitization require dissection, polymerase chain reaction (PCR), or waiting for adult emergence. The first two methods are relatively fast but destructive, whereas the third one allows the emergence of the parasitoid but it is time consuming. In this framework, new diagnostic imaging tools may contribute to solve the lack of an accurate, rapid, and non-invasive approach to evaluate the parasitization of soft-bodied insects by their endoparasitoids. In this study, ultra-high frequency ultrasound (UHFUS) technology, which is currently used in medical and preclinical fields, was adopted to assess the parasitization of the invasive polyphagous Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae), testing 2nd and 3rd instar larvae. Parasitization assays were carried out with the solitary koinobiont endophagous parasitoid Psyttalia concolor (Hymenoptera: Braconidae: Opiinae). The efficacy of UHFUS-based echoentomography was compared with the classical method of dissecting the larval host under a stereomicroscope. Our results showed that the UHFUS diagnostic capability was statistically comparable with that of dissection, both on C. capitata 2nd and 3rd larvae. Overall, UHFUS-based echoentomography may be further considered as a fast, non-invasive, and effective approach to evaluate the parasitoid's ability to successfully oviposit in soft-bodied hosts.

Musculoskeletal involvement of COVID-19: review of imaging

The global pandemic of coronavirus disease 2019 (COVID-19) has revealed a surprising number of extra-pulmonary manifestations of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. While myalgia is a common clinical feature of COVID-19, other musculoskeletal manifestations of COVID-19 were infrequently described early during the pandemic. There have been emerging reports, however, of an array of neuromuscular and rheumatologic complications related to COVID-19 infection and disease course including myositis, neuropathy, arthropathy, and soft tissue abnormalities. Multimodality imaging supports diagnosis and evaluation of musculoskeletal disorders in COVID-19 patients. This article aims to provide a first comprehensive summary of musculoskeletal manifestations of COVID-19 with review of imaging.

Incidence, Diagnosis, and Management of Neuromas Following Radiofrequency Ablation Treatment: a Narrative Review

OBJECTIVE

To determine the epidemiology of neuroma formation as a complication following radiofrequency ablation for chronic pain conditions as well as reviewing the diagnosis and management of neuromas.

DESIGN

Evidence-based narrative review and critical appraisal of literature.

RESULTS

A comprehensive review of the literature generated one case report describing neuroma formation following lumbar facet medial branch radiofrequency denervation. The rare incidence may be explained by neuroma pathophysiology and peripheral nerve injury produced by radiofrequency ablation, in combination with its asymptomatic nature. Diagnosis of neuromas is predominantly confirmed by clinical history and physical exam with potential for nerve blocks or imaging. Ultrasound has been suggested as a primary imaging modality with magnetic resonance imaging as a secondary option. Neuroma management ranges from conservative therapy to surgery with varying success rates.

CONCLUSIONS

Neuroma formation following radiofrequency ablation procedures is exceedingly rare and could be a hypothetical concern in clinical practice. However, the true incidence may be inaccurate given the asymptomatic nature of neuromas.

Performance Evaluation of High-Resolution Ultrasound versus Magnetic Resonance Imaging in Diagnosing Peripheral Nerve Pathologies

Background  High-resolution ultrasound (HRUS) and magnetic resonance neurography (MRN) are considered complementary to clinical and neurophysiological assessment for neuropathies.

Aims  The aim of our study was to compare the accuracy of HRUS and MRN for detecting various peripheral nerve pathologies, to choose the correct investigation to facilitate prompt patient management.

Materials and Methods  This prospective study was done using HRUS with 14 MHz linear-transducer and 3 or 1.5T MR in cases referred for the assessment of peripheral nerve pathologies. Image interpretation was done using a scoring system (score 0–3 confidence level) to assess for nerve continuity/discontinuity, increased nerve signal/edema, fascicular change, caliber change, and neuroma/mass lesion. We determined the accuracy, sensitivity, and specificity of these modalities compared with the diagnostic standard determined by surgical and/or histopathological, if not performed then clinical and/or electrodiagnostic evaluation.

Results  The overall accuracy of MRN was 89.3% (specificity: 66.6%, sensitivity: 92.6%, negative predictive value [NPV]: 57.1%, positive predictive value [PPV]: 95%) and that of HRUS was 82.9% (specificity: 100%, sensitivity: 80.4%, NPV: 42.8, PPV: 100). The confidence level for detecting nerve discontinuity and change in nerve caliber was found to be higher on ultrasonography than magnetic resonance imaging (MRI) (100 vs. 70% and 100 vs. 50%, respectively). Pathology of submillimeter caliber nerves was accurately detected by HRUS and these could not be well-visualized on MRI.

Conclusion  HRUS is a powerful tool that may be used as the first-line imaging modality for the evaluation of peripheral nerve pathologies, and a better means of evaluation of peripheral nerves with submillimeter caliber.

Ultrasound Imaging of the Deep Peroneal Nerve

Ultrasound is considered an excellent imaging modality to evaluate the nerves of the limbs. The deep peroneal nerve (DPN) is one of the terminal branches of the common peroneal nerve. The DPN may be affected by various disorders, which may be clinically challenging to show. This Pictorial Essay reviews the normal ultrasound anatomy of the DPN and presents disorders that may involve the nerve and its main branches along its course, from proximal to distal.

Ultrasonography evaluation of the normal ulnar nerve in adult: Comparison of the cross-sectional area at elbow extension and flexion

Background

Cross-sectional area (CSA) measurement of the ulnar nerve in the adult population by using ultrasonography (US) at elbow extension and flexion has previously been reported, but not much evidence showed a significant difference between elbow extension and flexion position.

Purpose

To compare the ulnar nerve CSA between elbow extension and flexion position.

Methods

A comparative cross-sectional study was conducted by involving 36 healthy adults with normally functioning ulnar nerve proven by Nerve Conduction Study (NCS) or Electroneurography. The ulnar nerve CSA was measured on each elbow by using US at the level of the medial epicondyle, 2 cm distal and 2 cm proximal from the medial epicondyle.

Results

The average ulnar nerve CSA at the medial epicondyle, 2 cm distal and proximal to the medial epicondyle at elbow extension respectively were 5.95 ± 0.74 mm2, 6.27 ± 0.92 mm2, and 5.92 ± 0.73 mm2. At elbow flexion, the average ulnar nerve CSA at the positions was 5.70 ± 0.83 mm2, 5.23 ± 0.87 mm2, dan 5.73 ± 0.71 mm2 respectively. The CSA of the ulnar nerve at elbow extension was significantly larger compared to the flexion position in the three areas observed in this study (p < 0.001).

Conclusion

The CSA of the ulnar nerve at elbow extension position was larger compared to the flexion position. Elbow position should be considered in measuring CSA of the ulnar nerve.

Traumatic Injuries to the Spinal Cord and Peripheral Nervous System

Both blunt and penetrating trauma can cause injuries to the peripheral and central nervous systems. Emergency providers must maintain a high index of suspicion, especially in the setting of polytrauma. There are 2 major classifications of peripheral nerve injuries (PNIs). Some PNIs are classically associated with certain traumatic mechanisms. Most closed PNIs are managed conservatively, whereas sharp nerve transections require specialist consultation for urgent repair. Spinal cord injuries almost universally require computed tomography imaging; some require emergent magnetic resonance imaging. Providers should work to minimize secondary injury. Surgical specialists are needed for closed reduction, surgical decompression, or stabilization.

Imaging Review of Peripheral Nerve Injuries in Patients with COVID-19

With surging numbers of patients with coronavirus disease 2019 (COVID-19) throughout the world, neuromuscular complications and rehabilitation concerns are becoming more apparent. Peripheral nerve injury can occur in patients with COVID-19 secondary to postinfectious inflammatory neuropathy, prone positioning-related stretch and/or compression injury, systemic neuropathy, or nerve entrapment from hematoma. Imaging of peripheral nerves in patients with COVID-19 may help to characterize nerve abnormality, to identify site and severity of nerve damage, and to potentially elucidate mechanisms of injury, thereby aiding the medical diagnosis and decision-making process. This review article aims to provide a first comprehensive summary of the current knowledge of COVID-19 and peripheral nerve imaging.

Quantitative Evaluation of the Echo Intensity of Paraneural Area and Myofascial Structure around Median Nerve in Carpal Tunnel Syndrome

The aim of this study was to investigate whether the echo intensity (EI) of the paraneural area (PA), the median nerve (MN) at the carpal tunnel, the EI of the myofascial structure (MS) around MN, the ‘PA and MN’ at the mid-forearm, and the MN transversal displacement at both sites differs between persons with carpal tunnel syndrome (CTS) and control subjects. Methods: In total, 16 CTS patients and 16 controls, age- and gender-matched, were recruited. Cross-sectional ultrasound images of MN were obtained to evaluate the EI of the PA, the MN at carpal tunnel, the EI of MS, and the ‘PA and MN’ at the mid-forearm in a natural position, then images were taken after a whole-hand grasp movement, to evaluate MN transversal displacement. Inter-rater and intra-rater reliability in control, and differences in the EI and MN displacement between CTS and control, were analyzed. In addition, the correlations between ultrasound parameters and MN displacement were evaluated. Results: The quantitative EI of PA, MN, EI of MS, ‘PA and MN’ had high inter-rater and intra-rater reliability in the control. The EI of PA, MS and ‘PA and MN’ were significantly higher in CTS subjects (p < 0.01), whilst there was no significant difference in the EI of MN at the carpal tunnel. MN displacement was significantly decreased both at the carpal tunnel and the mid-forearm in CTS subjects (p < 0.01). In addition, there were negative correlations among the EI of PA (rs = −0.484, p = 0.004), EI of MS (rs = −0.479, p = 0.002), EI of ‘PA and MN’ (rs = −0.605, p < 0.001) and MN transversal displacement. Conclusions: The higher EI of PA and MS around MN in CTS may indicate greater fibrosis along the course of MN, reducing fascial adaptability, influencing the synergy and coordination of the MS, and increasing the shear stress between MS and MN, and it may further increase the abnormal pressure on the MN not only at the carpal tunnel, but also at the mid-forearm. These results may partly explain the role of PA and MS in CTS pathogenesis.

Artifacts in Musculoskeletal Ultrasonography: From Physics to Clinics

Ultrasound appears to be the most useful imaging tool in the diagnosis and guided treatment of musculoskeletal disorders. However, ultrasonography has been criticized for being user dependent. Therefore, medical professionals should be familiar with the basic principles of ultrasound imaging (e.g., physics and technical skills) to diminish artifacts and avoid misinterpretation. In this review, we focused on the physics of common artifacts, their clinical significance, and the ways to tackle them in daily practice during musculoskeletal imaging. In particular, artifacts pertaining to the focal zone, beam attenuation, path and side lobe of the beam, speed of the sound, and range ambiguity were described.

Artifacts in Musculoskeletal Ultrasonography: From Physics to Clinics

Ultrasound appears to be the most useful imaging tool in the diagnosis and guided treatment of musculoskeletal disorders. However, ultrasonography has been criticized for being user dependent. Therefore, medical professionals should be familiar with the basic principles of ultrasound imaging (e.g., physics and technical skills) to diminish artifacts and avoid misinterpretation. In this review, we focused on the physics of common artifacts, their clinical significance, and the ways to tackle them in daily practice during musculoskeletal imaging. In particular, artifacts pertaining to the focal zone, beam attenuation, path and side lobe of the beam, speed of the sound, and range ambiguity were described.

Magnetic resonance imaging of the wrist and hand

The anatomy of the wrist and hand is complex and contains numerous small structures. Magnetic resonance imaging (MRI) is often an ideal imaging modality in the assessment of various traumatic and pathologic conditions of this region, and it is frequently performed after initial radiographs. In this manuscript we describe the normal anatomy, imaging techniques, and MRI findings of various traumatic and pathologic conditions of the wrist and hand including occult fractures, osteonecrosis, ligamentous and tendon injuries, and entrapment neuropathies.

Techniques for Peripheral Nerve Stimulator Implantation of the Upper Extremity

OBJECTIVE

To present a technical note on how to perform upper extremity peripheral nerve stimulators for three major nerves: median, ulnar, and radial.

DESIGN

Literature review and expert opinion.

SETTING

Single academic center.

RESULTS

Peripheral nerve stimulation has recently become popular with the development and availability of peripheral nerve stimulators with an external pulse generator. Here, we describe ultrasound anatomy and technical details for peripheral nerve stimulation in the upper extremity for three major nerves: median, ulnar, and radial.

CONCLUSIONS

Upper extremity peripheral nerve stimulation can be considered as an option for refractory neuropathic upper extremity pain.

Clinical indications for image guided interventional procedures in the musculoskeletal system: a Delphi-based consensus paper from the European Society of Musculoskeletal Radiology (ESSR)-part III, nerves of the upper limb

BACKGROUND

Image-guided interventional procedures of the nerves are commonly performed by physicians from different medical specialties, although there is a lack of clinical indications for these types of procedures. This Delphi-based consensus provided a list of indications on image-guided interventional procedures for nerves of the upper limb based on updated published evidence.

METHODS

An expert panel of 45 members of the Ultrasound and Interventional Subcommittees of the ESSR participated in this Delphi-based consensus study. After revision of the published papers on image-guided interventional procedures for nerves of the upper limb updated to September 2018, the experts drafted a list of statements according to the Oxford Centre for evidence-based medicine levels of evidence. Consensus on statements regarding clinical indications was considered as strong when more than 95% of experts agreed, and broad if more than 80% agreed.

RESULTS

Ten statements were drafted on procedures for nerves of the upper limb. Only two statements reached the highest level of evidence (ultrasound guidance is a safe and effective method for brachial plexus block; ultrasound-guided non-surgical approaches are safe and effective methods to treat carpal tunnel syndrome in the short term, but there is sparse evidence on the mid- and long-term effectiveness of these interventions). Strong consensus was obtained on 6/10 statements (60%), while 4/10 statements reached broad consensus (40%).

CONCLUSIONS

This Delphi-based consensus study reported poor evidence on image-guided interventional procedures for nerves of the upper limb. Sixty percent of statements on clinical indications provided by the expert board reached a strong consensus.

KEY POINTS

• An expert panel of the ESSR provided 10 evidence-based statements on clinical indications for image-guided interventional procedures for nerves of the upper limb • Two statements reached the highest level of evidence • Strong consensus was obtained on 6/10 statements (60%), while 4/10 statements reached broad consensus (40%).

Ultrasound Imaging of the Brachial Plexus and Nerves About the Neck

This review describes techniques for sonographic evaluation of the brachial plexus and multiple regional nerve branches in the neck, essential for successful implementation of neurosonology in the neck. High-frequency ultrasound transducers have the ability to produce superior, high-resolution images, allowing for superb depiction of nerve fascicular anatomy. Sonographic appearances of normal nerve anatomy and nerve-specific pathology are reviewed. Benefits and limitations of ultrasound nerve imaging compared with magnetic resonance imaging are discussed.