Cross-sectional area reference values for nerve ultrasonography

Peripheral neuropathy in systemic lupus erythematosus: what can neuromuscular ultrasonography (NMUS) tell us? A cross-sectional study

OBJECTIVE

To evaluate peripheral nerve involvement in patients with SLE with neuromuscular ultrasonography (NMUS) and understand its role in investigating SLE-related peripheral neuropathy.

METHODS

This is an observational cross-sectional study on patients with SLE and healthy controls. Five nerves in each patient were examined bilaterally with NMUS, and the cross-sectional area (CSA) of each nerve at certain sites was estimated. The mean CSA at each site, for each nerve, in each group was statistically analysed and compared between groups.

RESULTS

370 nerves were evaluated in 37 patients. By nerve conduction study (NCS), 36 patients had polyneuropathy (80.6% mixed type, 19.4% sensory). Significant mean CSA enlargement was present among the ulnar nerve at the Guyon's canal and mid-humerus (both p=0.001); tibial nerve at the distal leg and proximal to the tarsal tunnel (p=0.003 and p=0.001, respectively); and peroneal nerve at the popliteal fossa (p=0.042). The mean CSA showed high specificity compared with NCS.

CONCLUSION

Our study shows that CSA could be a complementary tool to NCS for studying peripheral neuropathy in SLE. Furthermore, NMUS provides data on the different pathophysiological aspects of nerve involvement in SLE. Future studies using more than one sonographic parameter in combination with NCS and nerve histopathology are recommended to further investigate SLE-related neuropathy.Trial registration number NCT04527172.

Shear wave elastography of the radial nerve in healthy subjects

Objective

This study was performed to examine the sonoelastographic features of the radial nerve in healthy subjects.

Methods

In this observational cross-sectional study, shear wave elastography was used to evaluate the radial nerve. The cross-sectional area and stiffness were measured.

Results

The study included 37 nerves in 20 healthy adult subjects. The mean cross-sectional area of the radial nerve at the arm was 6.1 mm². The mean stiffness of the radial nerve in the short axis was 30.3 kPa, and that in the long axis was 34.9 kPa. The elasticity measurements were significantly different between the long axis and short axis.

Conclusion

The elastic modulus of the radial nerve was studied in healthy subjects and can serve as a reference for future assessment of different radial nerve pathologies.

Cross-sectional area reference values for peripheral nerve ultrasound in adults: A systematic review and meta-analysis-Part II: Lower extremity nerves

BACKGROUND AND PURPOSE

Measurement of the cross-sectional area (CSA) of peripheral nerves using ultrasound is useful in the evaluation of focal lesions such as entrapment syndromes and inflammatory polyneuropathies. We performed a systematic review and meta-analysis of published CSA reference values for lower extremity nerves.

METHODS

We included available-to-date nerve ultrasound studies on healthy adults and provide meta-analysis for CSA of the following nerves: fibular nerve at fibular head, popliteal fossa; tibial nerve at popliteal fossa, malleolus; and sural nerve at the level of the two heads of gastrocnemius muscle. We report regression and correlation analyses for age, gender distribution, height, weight, and geographic continent.

RESULTS

We included 16 studies with 1001 healthy volunteers (mean age = 47.9 years) and 4023 examined nerve sites. Calculated mean pooled CSA of fibular nerve at fibular head was 8.4 mm² (95% confidence interval [CI] = 6.8-9.9 mm² , n = 1166), at popliteal fossa was 7.9 mm² (95% CI = 6.6-9.2 mm² , n = 995), of tibial nerve at popliteal fossa was 25.9 mm² (95% CI = 17.5-34.4 mm² , n = 771), at malleolus was 10.0 mm² (95% CI = 7.7-12.4 mm² , n = 779), and of sural nerve was 2.4 mm² (95% CI = 1.7-3.1 mm² , n = 312). Substantial heterogeneity across studies (I²  > 50%) was found only for tibial nerve at popliteal fossa. Subgroup analysis revealed a lower CSA of tibial nerve at popliteal fossa and sural nerve in studies conducted in Europe than in North America and New Zealand.

CONCLUSIONS

We provide the first meta-analysis on CSA reference values for the lower extremities with no or low heterogeneity of reported CSA values in all nerve sites except tibial nerve at popliteal fossa. Our data facilitate the goal of an international standardized evaluation protocol.

Cross-sectional area reference values for high-resolution ultrasonography of the upper extremity nerves in healthy Asian adults

In this study, multiple-site, cross-sectional area (CSA) reference values were established for major peripheral nerves, including small branches, in the upper extremity of a healthy Asian population.This study included 107 prospectively recruited age-matched, healthy subjects with a mean age of 46 years (range, 24-75 years). All subjects underwent standardized nerve conduction studies for the median, ulnar, peroneal, posterior tibial, and sural nerves. CSA was measured unilaterally at 21 sites of the median, ulnar, radial, posterior interosseous, superficial radial sensory, musculocutaneous, lateral antebrachial cutaneous, and medial antebrachial cutaneous nerves.According to their age, the subjects were assigned to the younger group (20-40 years, n = 40), the middle group (40-59 years, n = 40), and the older group (60-80 years, n = 27). The significant differences of CSA values between age groups were found only at certain sites, such as the median (wrist, P = .003), ulnar (medial epicondyle, P = .031; forearm, P = .022), radial (antecubital fossa, P = .037), and superficial radial sensory nerve (P = .028). The CSA significantly correlated with gender, height, weight, and body mass index.This study provides CSA reference values for nerves, including small sensory nerves in the upper extremity, which can be useful in the ultrasonographic investigation of various peripheral neuropathies in the upper extremity.

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.

High resolution ultrasonography of peripheral nerves in diabetic patients to evaluate nerve cross sectional area with clinical profile

OBJECTIVES

The aim of this observational study was ultrasound evaluation of peripheral nerves cross-sectional area (CSA) in subjects with probable diabetic peripheral sensorimotor neuropathy (DPN). CSA was analyzed with reference to clinical and nerve conduction study's (NCS) parameters for early diagnosis and pattern of involvement.

METHODS

A total of 50 patients with probable DPN due to Type 2 diabetes and 50 age-matched healthy controls underwent sonographic examinations of ulnar nerve at the lower arm, median nerve proximal to carpal tunnel, the common peroneal nerve proximal to fibular head, tibial nerve proximal to the tarsal tunnel, and sural nerve at lower third leg.

RESULTS

CSA was increased in cases of DPN as compared to healthy controls. Area changes were more marked with demyelinating pattern. Probable DPN cases with normal NCS had significantly higher number of peripheral nerves showing increased CSA as compared to healthy control. A cut-off of >4 nerve thickening showed a sensitivity of 86 %, and specificity of 56%. The neuropathy pattern in the lower limb was axonal, whereas in the upper limb, it was demyelinating with the majority showing sonographic feature of associated compressive neuropathy.

CONCLUSION

There is an increase in CSA of peripheral nerve in diabetic patients. It can be used as a morphological marker for classifying DPN with changes being picked up earlier to NCS abnormality. Clinical neurological presentation in probable DPN can also be due to compressive neuropathy in early phases, and ultrasound can be a useful tool.

ADVANCES IN KNOWLEDGE

Early pick up of DPN cases shall be useful for early therapy and motivating the patients to actively participate in the treatment. Morphological changes on ultrasonography precedes the electrodiagnostic change in DPN. Symptoms of DPN is not only due to metabolic changes but also compressive neuropathy.

Cross-sectional area reference values for peripheral nerve ultrasound in adults: a systematic review and meta-analysis-Part I: Upper extremity nerves

BACKGROUND AND PURPOSE

Measurement of the cross-sectional area (CSA) of peripheral nerves using ultrasound is useful in the evaluation of focal lesions like entrapment syndromes and inflammatory polyneuropathies. Here, a systematic review and meta-analysis of published CSA reference values for upper extremity nerves was performed.

METHODS

Available to date nerve ultrasound studies on healthy adults were included and a meta-analysis for CSA was provided of the following nerves: median nerve at the wrist, forearm, upper arm; ulnar nerve at the Guyon's canal, forearm, elbow, upper arm; radial nerve at the upper arm. Regression and correlation analyses for age, gender, height, weight, geographic continents and publication year are reported.

RESULTS

Seventy-four studies with 4186 healthy volunteers (mean age 42.7 years) and 18,226 examined nerve sites were included. The calculated mean pooled CSA of the median nerve at the wrist was 8.3 mm2 (95% confidence interval [95% CI] 7.9-8.7, n = 4071), at the forearm 6.4 mm2 (95% CI 5.9-6.9, n = 3021), at the upper arm 8.3 mm2 (95% CI 7.5-9.0, n = 1388), of the ulnar nerve at the Guyon's canal 4.1 mm2 (95% CI 3.6-4.6, n = 1688), at the forearm 5.2 mm2 (95% CI 4.8-5.7, n = 1983), at the elbow 5.9 mm2 (95% CI 5.4-6.5, n = 2551), at the upper arm 6.6 mm2 (95% CI 5.1-6.1, n = 1737) and of the radial nerve 5.1 mm2 (95% CI 4.0-6.2, n = 1787). Substantial heterogeneity across studies (I2 > 50%) was found only for the radial nerve. Subgroup analysis revealed a positive effect of age for the median nerve at the wrist and for height and weight for different sites of the ulnar nerve.

CONCLUSION

The first meta-analysis on CSA reference values for the upper extremities with no or only low heterogeneity of reported CSA values in most nerve sites is provided. Our data facilitate the goal of an international standardized evaluation protocol.

Impact of anatomical variations on ultrasonographic reference values of lower extremity peripheral nerves

INTRODUCTION/AIMS

Cross-sectional area (CSA) reference values using ultrasonography vary widely for lower extremity peripheral nerves. In addition, there is a lack of data on the muscular branches of the tibial nerve and the anatomical variations of the sural nerve. We aimed to evaluate the ultrasonographic reference values for lower extremity peripheral nerves considering different anatomical variations and physical factors.

METHODS

The CSA of the lower extremity nerve was measured at 10 sites. In addition to establishing reference values, differences in the CSA owing to anatomical variations were verified. The relationship between CSA and physical factors, such as age, height, weight, body mass index, and ankle circumference, was also examined.

RESULTS

A total of 100 healthy Japanese volunteers were recruited. The mean CSA of the sural nerve significantly differed depending on its formation pattern (1.4-1.8 mm² ). The mean decreases in CSAs from the proximal to distal tibial and fibular nerves within the popliteal region significantly differed based on the fine branching pattern. The maximum value of the mean decreases in CSAs in the tibial and fibular nerves reached 7.2 and 2.5 mm² , respectively. With respect to physical factors, age and ankle circumferences were associated with CSA at several measurement sites.

DISCUSSION

Fine branching from the tibial and fibular nerves and sural nerve formation may affect CSA measurements. The establishment of accurate CSA reference values requires consideration of anatomical variations in the peripheral nerves of the lower extremity.

High-resolution ultrasound changes of the vagus nerve in idiopathic Parkinson's disease (IPD): a possible additional index of disease

Background and rationale

Histopathological studies revealed degeneration of the dorsal motor nucleus of the vagus nerve (VN) early in the course of idiopathic Parkinson’s disease (IPD). Degeneration of VN axons should be detectable by high-resolution ultrasound (HRUS) as a thinning of the nerve trunk. In order to establish if the VN exhibits sonographic signs of atrophy in IPD, we examined patients with IPD compared with age-matched controls.

Material and methods

We measured the caliber (cross-sectional area, CSA) and perimeter of the VN in 20 outpatients with IPD (8 females and 12 males; mean age 73.0 + 8.6 years) and in age-matched controls using HRUS. Evaluation was performed by blinded raters using an Esaote MyLab Gamma device in conventional B-Mode with an 8–19 MHz probe.

Results

In both sides, the VN CSA was significantly smaller in IPD outpatients than in controls (right 2.37 + 0.91, left 1.87 + 1.35 mm² versus 6.0 + 1.33, 5.6 + 1.26 mm²; p <0.001), as well as the perimeter (right 5.06 + 0.85, left 4.78 + 1.74 mm versus 8.87 + 0.86, 8.58 + 0.97 mm; p <0.001). There were no significant correlations between VN CSA and age, the Hoehn and Yahr scale, L-dopa therapy, and disease duration.

Conclusion

Our findings provide evidence of atrophy of the VNs in IPD patients by HRUS. Moreover, HRUS of the VN represent a non-invasive easy imaging modality of screening in IPD patients independent of disease stage and duration and an interesting possible additional index of disease.

Reference values for lower limb nerve ultrasound and its diagnostic sensitivity

We aimed to establish the cross-sectional area (CSA) reference values for peripheral nerves of lower extremities in a healthy Chinese population, and to determine their diagnostic values for chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and Charcot-Marie-Tooth disease type1A (CMT1A). One hundred eleven healthy subjects, 15-70 years of age, as well as 104 CIDP patients and 26 CMT1A patients were recruited. CSA at predetermined sites of the tibial, fibular, sciatic and sural nerves was measured. The CSA of the tibial nerve ranged from 10.2 ± 1.9 to 20.7 ± 3.6 mm², and for fibular nerve from 8.4 ± 1.8 to 9.5 ± 1.9 mm². 86% CIDP patients had upper limb nerve enlargement, while only 67% had lower limb nerve enlargement. In CIDP patients with normal upper limb ultrasound, 56% (5/9) would have lower limb nerve enlargement. All CMT1A patients had both upper and lower limb nerve enlargement. Addition of lower limb nerve ultrasound showed no added value in diagnosis of CMT1A, but could be supplementary for CIDP when upper limb ultrasound is normal.

The Role of Imaging for Disorders of Peripheral Nerve

Peripheral nerve imaging is a helpful and sometimes essential adjunct to clinical history, physical examination, and electrodiagnostic studies. Advances in imaging technology have allowed the visualization of nerve structures and their surrounding tissues. The clinical applications of ultrasound and magnetic resonance imaging (MRI) in the evaluation of peripheral nerve disorders are growing exponentially. This article reviews basics of ultrasound and MRI as they relate to nerve imaging, reviews advantages and limitations of each imaging modality, reviews the applications of ultrasound and MRI in disorders of peripheral nerve, and discusses emerging advances in the field.

Enhancing diagnostic accuracy using a side-to-side cross-sectional area ratio for the diagnosis of unilateral ulnar mononeuropathy at the elbow

INTRODUCTION

Neuromuscular ultrasonography (NMUS) is a valuable adjunct to electrodiagnostic testing for the diagnosis of entrapment neuropathy. The aim of this study was to determine whether diagnostic accuracy of NMUS could be enhanced in patients with unilateral ulnar mononeuropathy at the elbow (UNE) by utilizing side-to-side ulnar nerve cross-sectional area (CSA) ratios.

METHODS

Retrospective case-control analysis of unilateral UNE cases identified cutoff values for elbow segment ulnar nerve maximum CSA (MCSA) of the symptomatic/asymptomatic limb (M ratio), as well as side-to-side ratios comparing MCSA with ipsilateral CSA at the Guyon canal (E/G), middle forearm (E/F), and middle humerus (E/H). Diagnostic accuracy values were calculated.

RESULTS

The optimal M-ratio cut-off was 1.22 (sensitivity, 92.9%; specificity, 97.8%; accuracy, 95.4%). Optimal cutoffs for inter-E/G, -E/F, and -E/H ratios were 1.07 (sensitivity, 98%; specificity, 78%; accuracy, 87.7%), 1.11 (sensitivity, 95%; specificity, 80%; accuracy, 87.2%), and 1.18 (sensitivity, 95%; specificity, 93%; accuracy, 94%), respectively.

DISCUSSION

The M ratio and inter-E/H ratio exhibited high diagnostic accuracy for unilateral UNE. Prospective studies are needed to compare the accuracy of the new measures with a single MCSA measurement.

Ultrasound scanning in the diagnosis of peripheral neuropathies

Nerve ultrasound scanning has become a valuable diagnostic tool in the routine workup of peripheral nerve disorders, effectively complementing conventional electrodiagnostic studies. The most relevant sonographic features are nerve size and structural integrity. Several peripheral neuropathies show characteristic and distinct patterns of nerve enlargement, allowing their early and accurate identification, and reducing test-burden and diagnostic delay for patients. In mononeuropathies such as carpal tunnel syndrome and ulnar neuropathy at the elbow, nerve enlargement develops only at specific sites of entrapment, while in polyneuropathy the nerve enlargement may be multifocal, regional or even diffuse. Nerve ultrasound scanning can reliably identify chronic inflammatory neuropathies, even when extensive electrodiagnostic studies fail, and it should therefore be embedded in routine diagnostic workup of peripheral neuropathies. In this paper we describe a potential diagnostic strategy to achieve this.

Nerve Ultrasound as Helpful Tool in Polyneuropathies

Background: Polyneuropathies (PNP) are a broad field of diseases affecting millions of people. While the symptoms presented are mostly similar, underlying causes are abundant. Thus, early identification of treatable causes is often difficult. Besides clinical data and basic laboratory findings, nerve conduction studies are crucial for etiological classification, yet limited. Besides Magnetic Resonance Imaging (MRI), high-resolution nerve ultrasound (HRUS) has become a noninvasive, fast, economic and available tool to help distinguish different types of nerve alterations in neuropathies. Methods: We aim to describe typical ultrasound findings in PNP and patterns of morphological changes in hereditary, immune-mediated, diabetic, metabolic and neurodegenerative PNP. Literature research was performed in PubMed using the terms ‘nerve ultrasound’, neuromuscular ultrasound, high-resolution nerve ultrasound, peripheral nerves, nerve enlargement, demyelinating, hereditary, polyneuropathies, hypertrophy’. Results: Plenty of studies over the past 20 years investigated the value of nerve ultrasound in different neuropathies. Next to nerve enlargement, patterns of nerve enlargement, echointensity, vascularization and elastography have been evaluated for diagnostic terms. Furthermore, different scores have been developed to distinguish different etiologies of PNP. Conclusions: Where morphological alterations of the nerves reflect underlying pathologies, early nerve ultrasound might enable a timely start of available treatment and also facilitate follow up of therapy success.

Shear wave elastography of the tibial nerve in healthy subjects

The purpose of this study is to investigate sonoelastographic features of the tibial nerve.The study included 72 tibial nerves in 36 healthy subjects. High resolution ultrasound and Shear wave elastography were used to evaluate the tibial nerve. Cross sectional area and stiffness were measured.The mean cross sectional area of the tibial nerve was 13.4 mm2. The mean shear elastic modulus of the tibial nerve in the short axis was 23.3 kPa. The mean shear elastic modulus of the tibial nerve in long axis was 26.1 kPa. The tibial nerve elastic modulus also showed no correlation with cross sectional area neither in the long axis nor short axis. Age, height, weight, and body mass index showed no correlation with tibial nerve elastic modulus in short or long axes.The elastic modulus of the tibial nerve has been determined in healthy subjects and can serve as a reference for future assessment of polyneuropathy.

Nerve Ultrasound in Traumatic and Iatrogenic Peripheral Nerve Injury

Peripheral nerve injury is a potentially debilitating disorder that occurs in an estimated 2–3% of all patients with major trauma, in a similar percentage of medical procedures. The workup of these injuries has traditionally been clinical, combined with electrodiagnostic testing. However, this has limitations, especially in the acute phase of the trauma or lack of any recovery, when it is very important to determine nerve continuity and perform surgical exploration and repair in the case of the complete transection or intraneural fibrosis. Ultrasound can help in those situations. It is a versatile imaging technique with a high sensitivity of 93% for detecting focal nerve lesions. Ultrasound can assess the structural integrity of the nerve, neuroma formation and other surrounding abnormalities of bone or foreign bodies impeding the nerve. In addition, this can help to prevent iatrogenic nerve injury by marking the nerve before the procedure. This narrative review gives an overview of why and how nerve ultrasound can play a role in the detection, management and prevention of peripheral nerve injury.

Neuromuscular Ultrasound in the Pediatric Population

The diagnosis and evaluation of neuromuscular disorders traditionally involves electrodiagnostic (EDx) testing, including nerve conduction studies (NCSs) and electromyography (EMG). These tools can cause pain and discomfort, an important consideration when performed on children. Neuromuscular ultrasound is noninvasive, cost-effective, and increasingly utilized for the detection of neuromuscular pathology. Studies investigating the performance and clinical implementation of ultrasound have primarily been performed in adult populations. Ultrasound in children has the potential to guide EDx testing and ultimately improve diagnostic efficiency and accuracy. This review aims to describe key features of neuromuscular ultrasound in the pediatric population based on the available studies, including our own institutional experience.

Ultrasound Detection of Vagus Nerve Atrophy in Bulbar Amyotrophic Lateral Sclerosis

BACKGROUND AND PURPOSE

Neuromuscular ultrasound in amyotrophic lateral sclerosis (ALS) is of increasing interest. As bulbar symptoms are commonly developed by most ALS patients during disease, the aim of our study was to find possible sonographic changes of vagus nerve size in bulbar affected ALS patients.

METHODS

We investigated 24 ALS patients and 19 controls without neuromuscular disorders. In ALS patients, bulbar affection was documented clinically (eg, dysarthria, dysphagia, and fasciculations) or subclinically using ultrasound and electromyography of bulbar muscles. Vagus nerve ultrasound was performed in all participants bilaterally at the level of the thyroid gland.

RESULTS

The cross-sectional area (CSA) of the vagus nerve in bulbar affected ALS patients (mean CSA right/left 1.9 ± .7 mm²/1.8 ± .6 mm²) was significantly reduced on both sides compared to controls (mean CSA right/left 2.2 ± .6 mm²/2.0 ± .3 mm²) - right: P = .0387, left: P = .0386. Receiver operating characteristic curve analysis of the vagus nerve CSA yielded a sensitivity of 66.7% and a specificity of 63.2% (cutoff value 1.85 mm²). Vagus nerve CSA did not correlate significantly with age in controls (right: P = .45, left: P = .66). In controls and ALS patients, there was no significant difference of vagus nerve CSA between the right and left sides (controls: P = .43; patients: P = .86).

CONCLUSION

Our study demonstrates vagus nerve atrophy in bulbar affected ALS patients. Further studies are warranted investigating the relevance of our finding for monitoring disease progression in ALS.

Change in cross-sectional area of the median nerve with age in neonates, infants and children analyzed by high-resolution ultrasound imaging

AIM

To analyze age dependencies in the cross-sectional area (CSA) of the median nerve during early childhood.

METHOD

A total of 43 participants (32 of whom were children younger than 2 years) were included in this cross-sectional study to analyze the age dependency of the CSA of the median nerve at three locations (wrist, forearm and upper arm) using high-resolution ultrasound images.

RESULTS

A strong and highly significant correlation was found between age and CSA (p < 0.001). When plotted, the relationship followed a logarithmic curve (p < 0.001) with a growth rate that decreases with age. Based on the regression analysis, a temporally similar increase in CSA for all three locations was found. The nerve reaches 70% of its final CSA by 2 years of age at all three locations.

INTERPRETATION

Similar to the nerve conduction speed, the increase in CSA is greatest during the first 2 years of life. Then, the rate gradually and synchronously slows at the proximal and distal locations. Measurement of the CSA in the clinical setting might offer a new method to assess the maturation of the nervous system in infants with minimal interference.

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.

VNS implantation in a NF1 patient: massive nerve hypertrophy discovered intra-operatively preventing successful electrode placement. Case report

For the vast majority of surgeons, no specific investigation is necessary before vagal nerve stimulation (VNS) implantation. We report our intraoperative unexpected finding of a massively enlarged vagus nerve in a patient with neurofibromatosis type 1 (NF1). The nerve hypertrophy prevented wrapping the coils of the helical electrode. The patient had no signs of vagus nerve dysfunction preoperatively (no hoarseness or dysphonia). This exceptional mishap is undoubtedly related to NF1-associated peripheral nerve sheath tumors. Even though it is not advisable to routinely perform any imaging prior to VNS, in such specific context, preoperative imaging work-up, especially cervical ultrasound, might be judicious to rule out any asymptomatic enlarged left vagus nerve.

Cutaneous nerve-conscious surgical repair of vascular access-related aneurysm assisted by anatomical ultrasonography in hemodialysis patients

BACKGROUND

The superficial runoff veins anatomically run alongside the cutaneous nerves in the volar forearm. Consequently, the surgical repair of vascular access (VA)-associated venous aneurysms attached to the cutaneous nerves could cause intraoperative nerve injury. Therefore, we proposed a cutaneous nerve-conscious VA-related aneurysmal repair assisted by nerve ultrasonography. This ultrasonography aids in the preoperative examination of the courses of the nerves neighboring the aneurysm.

METHODS

Sixteen consecutive patients who underwent surgical revisions of VA-related aneurysms (14 venous aneurysms and two arterial pseudoaneurysms) were enrolled. The locations of aneurysms derived from preexisting arteriovenous fistulas included 11 radiocephalic arteriovenous fistulas in the wrist or distally, three radiocephalic arteriovenous fistulas at the antecubital fossa, and two brachiocephalic arteriovenous fistulas at the antecubital fossa or in the distal upper arm. A preoperative ultrasonographic scan of the cutaneous nerve trunks that ran peripherally toward and along the aneurysms was attempted to avoid nerve injuries during operations. Basically, the aneurysms were resected from the proximal to the distal ends after being separated from the preserved adjacent nerves.

RESULTS

The cutaneous nerve trunks that coursed toward and along the aneurysm could be identified by preoperative ultrasonography and could be preserved intraoperatively based on ultrasonographic findings in all patients. In four patients, the cutaneous nerve branch was unexpectedly or intentionally severed for a seamless surgical process because the nerve branch that divided from the cutaneous nerve trunk was strongly attached to the aneurysm. They subsequently suffered from hypoesthesia, but did not experience neuropathic pain.

CONCLUSION

Preoperative ultrasonographic examination of the cutaneous nerve facilitated the intraoperative prevention of cutaneous nerve injury in VA-related aneurysmectomy. Nerve-sparing VA surgery assisted by preoperative nerve ultrasonography based on the understanding of topological anatomy might contribute to the reduction in postoperative neuropathy and enhance comfort in the daily life of hemodialysis patients.

Ultrasonography of cervical nerve roots: cross-sectional reference values according to age

INTRODUCTION

The aim of this study is to describe the normal cross-sectional area (CSA) and appearance of cervical nerve roots in ultrasound, correlating it to age and other patient somatic parameters.

METHODS

One hundred healthy volunteers were included. We aimed to achieve uniform representation throughout all age groups. Ultrasound of the cervical nerve roots was performed bilaterally. CSA and margins description were obtained.

RESULTS

C5 nerve, 8.32 ± 2.30; C6 nerve, 11.88 ± 3.36; C7 nerve, 12.79 ± 3.85; C8 nerve, 11.20 ± 3.45. Significant correlation between CSA and age was demonstrated, but not for body mass index. Blurred margins were present in up to 23.71% cervical nerves, more frequently in older individuals and in C7 nerve.

DISCUSSION

If ultrasound morphology of cervical nerve roots is used as a diagnostic parameter, the normal range of CSA values and percentage of blurred margins according to age should be considered.

Current and future applications of ultrasound imaging in peripheral nerve disorders

Neuromuscular ultrasound (NMUS) is a rapidly evolving technique used in neuromuscular medicine to provide complimentary information to standard electrodiagnostic studies. NMUS provides a dynamic, real time assessment of anatomy which can alter both diagnostic and management pathways in peripheral nerve disorders. This review describes the current and future techniques used in NMUS and details the applications and developments in the diagnosis and monitoring of compressive, hereditary, immune-mediated and axonal peripheral nerve disorders, and motor neuron diseases. Technological advances have allowed the increased utilisation of ultrasound for management of peripheral nerve disorders; however, several practical considerations need to be taken into account to facilitate the widespread uptake of this technique.

Vagus Nerve Ultrasound in Chronic Inflammatory Demyelinating Polyradiculoneuropathy and Charcot-Marie-Tooth Disease Type 1A

BACKGROUND AND PURPOSE

Both clinical autonomic dysfunction and involvement of autonomic nerves have been reported in a range of peripheral nerve disorders. We employed nerve ultrasound to assess the size of the vagus nerve in a serial study of patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and Charcot-Marie-Tooth type 1B (CMT1B) as compared to healthy controls (HCs). We correlated these findings with involvement of the median and ulnar nerves.

METHODS

Forty-three patients with CIDP, 8 with CMT1A, and 105 HC were prospectively recruited. The cross-sectional areas (CSAs) of the vagus, median, and ulnar nerves were measured bilaterally. The alteration of CSA of those nerves was followed longitudinally in CIDP.

RESULTS

The median (range) CSA of the vagus nerve was 2 (1-28) mm² in CIDP, 3 (2-6) mm² in CMT1A, and 1 (1-2) mm² in HC. The vagus nerve CSA was positively correlated with the maximum CSA of median/ulnar nerve in CIDP and CMT1A. The alteration in vagus nerve CSA was positively correlated with the alteration in mean median/ulnar nerve CSA in CIDP during follow-up.

CONCLUSIONS

The vagus nerve was involved to a similar extent as the median and ulnar nerves in CIDP and CMT1A, although no symptoms or signs of vagus nerve involvement were found. Further study should be performed to explore the clinical relevance of vagus nerve enlargement in these disorders.

A Severe Form of M - protein Negative Distal Acquired Demyelinating Symmetric Neuropathy

Distal acquired demyelinating symmetric neuropathy (DADS) is a variant of chronic inflammatory demyelinating polyneuropathy (CIDP) characterized by symmetrical, distal, sensory or sensorimotor involvement. DADS with M-protein (DADS-M) is less responsive to immunotherapy compared to those without M-protein (DADS-I). We report a case of DADS-I with severe clinical presentation viz. early hand involvement with marked wasting, inexcitable peripheral nerves on neurophysiology and poor response to immunotherapy. Despite the unusual presentation, ancillary tests including cerebrospinal fluid analysis, nerve biopsy and nerve ultrasound were supportive of an inflammatory demyelinating polyneuropathy. This case demonstrated the heterogeneity of the disorder and expands the clinical spectrum of DADS neuropathy.

Standing Balance Performance and Knee Extensors' Strength in Diabetic Patients with Neuropathy

Diabetes peripheral neuropathy (DPN) leads to balance impairment among diabetes mellitus (DM). The aims of this study were to (1) distinguish between DM patients who have/do not have DPN and to (2) compare quadriceps' strength and balance performance of DM, DPN, and healthy groups. Fifteen healthy females and 33 females with type 2 diabetic patients participated. The electrodiagnostic method was used to classify diabetic patients into DM and DPN. A dynamometer was used to measure quadriceps' strength. Single-leg standing on a force plate was also used to quantify participants' balance. Smaller conduction velocity and amplitude and greater distal latency of all nerves were observed in the DPN compared with the DM in particular for sensory nerve. In DPN, conduction velocity was asymmetrical. The quadriceps' strength of both legs in DPN and the right leg in DM was smaller than in the control group. The root mean square of the center of pressure was similar between DM and DPN. But it was larger in DPN than in the control group. DPN is associated with asymmetrical conduction velocity, smaller quadriceps' strength, and weaker balance performance that is suggestive of higher risk of falling. Balance training is recommended for the DPN group during their rehabilitation to reduce their falling risk.

Feasibility of Point Shear Wave Elastography for Evaluating Diabetic Peripheral Neuropathy

OBJECTIVES

In the mode of Virtual Touch quantification (Siemens AG, Erlangen, Germany), point shear wave elastography (p-SWE) is widely used for noninvasive assessments of tissue stiffness, which may be useful in the evaluation of diabetic peripheral neuropathy (DPN).

METHODS

Thirty patients with type 2 diabetes and 20 control participants (7 with myoma of the uterus and 13 with kidney stones) were enrolled in this prospective study. The 30 patients were further divided into patients with DPN and patients without DPN. Conventional ultrasound examinations and p-SWE were used to examine the tibial nerve in the popliteal fossa.

RESULTS

Tibial nerve stiffness values in the overall patient group, patients with DPN, and patients without DPN were all significantly higher than in the control group (P < .05). The cutoff value of p-SWE for assessing DPN was 2.60 m/s; at that threshold, sensitivity was 63.33%, and specificity was 92.50%.

CONCLUSIONS

Point SWE was useful for the noninvasive assessment of DPN and had high specificity. The increased stiffness in patients without DPN indicated that the tibial nerve might be affected by diabetes.

Normative Observational Nerve Ultrasound Values in School-Age Children and Adolescents and Their Application to Hereditary Neuropathies

Backgrounds: We have aimed to establish nerve ultrasound reference data in 8 to 17-year-old children and adolescents and to compare those data to younger children, adults, and age-matched children with polyneuropathies.

Methods: High-resolution ultrasounds of the nerves were performed in 117 healthy children and adolescents at 20 predefined landmarks in the neck and the extremities of both sides. Mean values, side-to-side differences and intraneural ratios, as well as upper limits have been calculated. In a second step, a comparison between 25 children and adolescents of the same age range with proven hereditary and acquired neuropathies and lysosomal storage diseases has been carried out.

Results: Nerve growth correlates significantly with age and reaches adult values at the age of around 15 years. The influence of body mass index and gender is negligible at most segments. By the use of age-specific upper limits, nerve enlargement could be seen in distinct types of neuropathies, particularly in demyelinating hereditary and inflammatory types, which is comparable to findings in adults, but also in rare lysosomal storage diseases.

Conclusion: Nerve size correlates with age during childhood and reaches a climax in younger adults. Age-matched reference data are inevitable to differ between hypertrophic and non-hypertrophic nerve damage, e.g., in neuropathies.

Application value of conventional ultrasound and real-time shear wave elastography in patients with type 2 diabetic polyneuropathy

PURPOSE

To explore the application value of conventional ultrasound and real-time shear wave elastography (SWE) to the tibial nerve (TN) and the common peroneal nerve (CPN) in diabetic peripheral neuropathy (DPN).

MATERIALS AND METHODS

Thirty-three healthy volunteers, 33 diabetic patients without DPN, and 30 diabetic patients with DPN were enrolled in this study. The anteroposterior diameter (APD), the cross-sectional area (CSA), and the perimeter of the TN and the CPN were measured by conventional ultrasound, and the stiffness of the nerves was measured by SWE.

RESULTS

The conventional ultrasound parameters and stiffness of the TN in patients with DPN were significantly larger than those of the other two groups (P < 0.01). The conventional ultrasound parameters of the CPN were significantly higher in patients with DPN than in the other two groups (P < 0.01).The patients with DPN demonstrated a greater stiffness of the CPN compared to the control group (P < 0.05). The comparison of all parameters for the left and right TNs and CPNs among the three groups showed no significant difference. The area under the curve (AUC) of TN stiffness for the diagnosis of DPN was significantly greater than that of conventional ultrasound parameters.

CONCLUSION

The conventional ultrasound parameters and the stiffness of the TN and the CPN were significantly higher in patients with DPN. The stiffness of the TN could better diagnose DPN than conventional ultrasound parameters. In short, conventional ultrasound and SWE of nerves are of good application value in the diagnosis of DPN.

Ultrasonography of the Vagus Nerve in the Diagnosis of Parkinson's Disease

Background

It is currently impossible to diagnose Parkinson's disease (PD) in the premotor phase even though at the time of motor symptom onset the number of already degenerated dopaminergic substantia nigra neurons is considerable. Degeneration of the dorsal nucleus of the vagus nerve (VN) has been reported early in the disease course, and it could lead to impaired function of the VN, resulting in certain nonmotor symptoms of PD. Therefore, we raised a hypothesis that the loss of VN neurons could result in a smaller diameter of the VN among PD patients.

Methods

20 PD patients and 20 age- and gender-matched individuals without any neurodegenerative disease were enrolled in a pilot study. The diameters of the right and left VNs were measured using ultrasonography, their average was calculated, and the narrower VN diameter was noted separately.

Results

No difference was found between the PD and control groups neither in the average VN diameter (mean 1.17; 95% confidence interval (CI) 1.10–1.24 vs. 1.13; 1.07–1.18, mm; p=0.353) nor in the narrower VN diameter (mean 1.11; 95% confidence interval (CI) 1.02–1.20 vs. 1.07; 1.02–1.13, mm; p=0.421). The narrower VN diameter and the average VN diameter were not able to distinguish between PD patients and controls (area under curve (AUC) = 0.588, 95% CI = 0.408–0.767, and p=0.344; and AUC = 0.578, 95% CI = 0.396–0.759, and p=0.402).

Conclusions

To conclude, no differences were found in VN diameter between the PD and control groups. Therefore, our data do not support the hypothesis that PD could be associated with a smaller diameter of the VN.

Neuromuscular ultrasound for taxane peripheral neuropathy in breast cancer

BACKGROUND

Our study aim was to evaluate neuromuscular ultrasound (NMUS) for the assessment of taxane chemotherapy-induced peripheral neuropathy (CIPN), the dose-limiting toxicity of this agent.

METHODS

This cross-sectional study of breast cancer patients with taxane CIPN measured nerve cross-sectional area (CSA) by NMUS and compared with healthy historical controls. Correlations were determined between CSA and symptom scale, nerve conduction studies, and intraepidermal nerve fiber density (IENFD).

RESULTS

A total of 20 participants reported moderate CIPN symptoms at a median of 3.8 months following the last taxane dose. Sural nerve CSA was 1.2 mm² smaller than healthy controls (P ≤ .01). Older age and time since taxane were associated with smaller sural nerve CSA. For each 1 mm² decrease in sural nerve CSA, distal IENFD decreased by 2.1 nerve/mm (R² 0.30; P = .04).

CONCLUSIONS

These data support a sensory predominant taxane neuropathy or neuronopathy and warrant future research on longitudinal NMUS assessment of CIPN.

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.

Evaluating the functional and structural changes in the vagus nerve: Should the vagus nerve be tested in patients with atrial fibrillation?

One of the multiple factors believed to contribute to the initiation and maintenance of atrial fibrillation (AF) is altered activity of the autonomic nervous system. Debate continues about the role of the vagus nerve (CNX) in AF since its effect depends on the level of its activation as well as on simultaneous sympathetic activation. Surplus either vagal or sympathetic activity may rarely induce the development of AF; however, typically loss of balance between the both systems mediates the induction and maintenance of AF. Vagal stimulation has been proposed as a novel treatment approach for AF because the anti-arrhythmic effects of low-level vagus nerve stimulation have been shown both in patients and animal models. We hypothesize that in typical cases of AF without any clear trigger by either autonomic nervous system, significant changes in vagus somatosensory evoked potentials and a smaller cross-sectional area of CNX could be detected, representing functional and structural changes in CNX, respectively.

Ultrasound appearance of peripheral nerves in the neck: vagus, hypoglossal and greater auricular

Background and aim

Information in ultrasonography about reference values of nerves, particularly of those located in the neck is limited. The aim of the study is to demonstrate the feasibility of direct visualization of the vagus, hypoglossal and greater auricular nerves, testing the method on healthy volunteers and estimate the reference values for two perpendicular diameters and cross-sectional area (CSA).

Methods

A prospective study was carried out on 21 healthy volunteers (12 women and 9 men), recording their demographic characteristics. A 13 MHz transducer was used on a Hitachi EUB-8500 machine. The vagus nerve was measured at the bifurcation of common carotid artery (CCA) and at the intersection of the internal jugular vein with omohyoid muscle. The hypoglossal nerve was identified as it crosses the posterolateral border of the mylohyoid muscle in the submandibular space. The auricular nerve was identified on the superficial surface of the sternocleidomastoid muscle at 1 cm from its posterior margin. The mean CSA on axial scans, nerve width and thickness were determined. The side-to-side and gender differences of the estimated reference values and their correlations with the weight, height, and body mass index (BMI) were evaluated.

Results

The mean ultrasound-estimated CSA was measured for the vagus nerve at CCA bifurcation (2.14 ± 0.79 on the left 2.86 ± 1.27 on the right), vagus nerve at the level of omohyoid muscle (2.10 ± 0.06 on the left and 2.43 ± 0.08 on the right), hypoglossal nerve (1.71 ± 0.08 on the left, 1.24 ± 0.06 on the right) and greater auricular nerve (0.90 ± 0.53 on the left and 0.79 ± 0.71 on the right). The vagus nerve was significantly larger on the right side compared to the left side. Larger hypoglossal nerve was observed in men compared to women. Significant correlations were observed between weight and CSA of the greater auricular nerve.

Conclusion

Direct visualization of the vagus, greater auricular nerve and hypoglossal nerves is feasible. Reference values for the size of the studied nerves at specific anatomic landmarks were established. Side, gender and body weight differences of the nerves CSA were noted.

Nerve ultrasound reference data in children from two to seven years

OBJECTIVE

We examined selected peripheral and spinal nerves of children aged between two and seven years.

METHOD

High resolution ultrasound was performed in 116 children (2-7 years of age) at 19 predefined landmarks of median, ulnar, tibial, fibular, sural and radial nerves, the vagus as well as cervical spinal nerve 5 and 6. Further, side-to-side measuring and grey-scale analysis was done at selected nerve sites.

RESULTS

Nerves of children were on average smaller than those of adults. Nerve growth correlates significantly with age in all nerves, the mean values were similar in the age of two to four years and five to seven years. Body mass index (BMI) and gender showed moderate effect at some nerve sites, however not uniformly in all. A side-to-side difference of up to 30% in median, and up to 20% in tibial nerve can occur in healthy individuals. Grey-scale analysis for echointensity has been performed in median, ulnar and tibial nerves.

CONCLUSION

Nerve size increases with age, BMI and gender have moderate effect. A side-to-side-difference of up to 30% can exist.

SIGNIFICANCE

Reference values of nerve cross-sectional area, side-to-side-difference and echo intensity are necessary to detect nerve pathology in children as well as in adults.

Very early Guillain-Barré syndrome: A clinical-electrophysiological and ultrasonographic study

Objectives

Using recent optimized electrodiagnostic criteria sets, we primarily aimed at verifying the accuracy of the initial electrophysiological test in very early Guillain-Barré syndrome (VEGBS), ≤4 days of onset, compared with the results of serial electrophysiology. Our secondary objective was to correlate early electrophysiological results with sonographic nerve changes.

Methods

This is a retrospective study based on consecutive VEGBS patients admitted to the hospital. Each patient had serial nerve conduction studies (NCS) in at least 4 nerves. Initial NCS were done within 4 days after onset, and serial ones from the second week onwards. Electrophysiological recordings of each case were re-evaluated, GBS subtype being established accordingly. Nerve ultrasonography was almost always performed within 2 weeks after onset.

Results

Fifteen adult VEGBS patients were identified with a mean age of 57.8 years. At first NCS, VEGBS sub-typing was only possible in 3 (20%) cases that showed an axonal pattern, the remaining patterns being mixed (combining axonal and demyelinating features) in 6 (40%), equivocal in 5 (33.3%), and normal in 1 (6.7%). Upon serial NCS, 7 (46.7%) cases were categorized as acute demyelinating polyneuropathy, 7 (46.7%) as axonal GBS, and 1 (6.6%) as unclassified syndrome. Antiganglioside reactivity was detected in 5 out of the 7 axonal cases. Nerve US showed that lesions mainly involved the ventral rami of scanned cervical nerves.

Conclusions

Serial electrophysiological evaluation is necessary for accurate VEGBS subtype classification. Ultrasonography helps delineate the topography of nerve changes.

Significance

We provide new VEGBS pathophysiological insights into nerve conduction alterations within the first 4 days of the clinical course.

Neuromuscular ultrasound in clinical practice: A review

Neuromuscular ultrasound (NMUS) is becoming a standard element in the evaluation of peripheral nerve and muscle disease. When obtained simultaneously to electrodiagnostic studies, it provides dynamic, structural information that can refine a diagnosis or identify a structural etiology. NMUS can improve patient care for those with mononeuropathies, polyneuropathy, motor neuron disease and muscle disorders. In this article, we present a practical guide to the basics of NMUS and its clinical application. Basic ultrasound physics, scanning techniques and clinical applications are reviewed, along with current challenges.

Ultrasound in Multifocal Motor Neuropathy: Clinical and Electrophysiological Correlations

OBJECTIVES

Multifocal motor neuropathy (MMN) is a treatable autoimmune polyneuropathy, which may prove challenging diagnostically in the setting of absent conduction blocks or advanced axonal loss. Relatively few studies have examined the role of ultrasound (US) in MMN.

METHODS

Retrospective, cross-sectional study of patients with MMN who underwent peripheral nerve US. Charts were reviewed to extract clinical, sonographic, and electrophysiological data.

RESULTS

Eleven patients with MMN underwent US between 2013 and 2015; of these 11 patients, 7 had ≥3 abnormal nerve segments, and 6 had ≥5 sites of increased cross-sectional area (CSA). There was moderate correlation between the degree of amplitude drop observed in the median and ulnar motor nerves, and CSA. Significant correlation between CSA and limb strength was only observed for the median nerve.

CONCLUSIONS

Peripheral nerve US shows promise as a diagnostic tool in MMN and may be helpful to distinguish MMN from motor neuron disease.

A prospective study of high resolution ultrasound in brachial plexopathies - Correlation with electrophysiological measurements

OBJECTIVES

To evaluate the diagnostic role of ultrasound in brachial plexopathies.

METHODS

We included 59 healthy subjects (HS) and 42 patients consecutively referred with clinical suspicion of brachial plexopathy from October 2015 to May 2016. Patients underwent routine electrodiagnostic testing (EDx) as reference standard and a blinded standardised ultrasound examination of the brachial plexus as index test with cross-sectional area (CSA) as the ultrasound parameter of choice.

RESULTS

Seventeen patients were diagnosed by EDx with brachial plexopathy, ten with mononeuropathies, and ten had normal EDx. Five had a cervical radiculopathy. In 11 (64%) out of the 17 patients with EDx diagnosed plexopathy, we found at least one abnormal level on ultrasound. Six (60%) out of ten normal EDx patients had a normal ultrasound examination at all levels. Ultrasound identified the same abnormal level(s) as EDx in eight (73%) of the 11 patients who had both abnormal EDx and ultrasound results. Mean CSA was higher in the plexopathy group compared to HS at the level of the C6 root (p = .022), the middle trunk (p = .027), and the medial cord (p = .003).

CONCLUSION

Ultrasound examination showed abnormalities in patients with brachial plexopathies in good agreement with EDx.

SIGNIFICANCE

Ultrasound may be an important supplement to electrodiagnostics in evaluating brachial plexopathies.

Amyotrophic Lateral Sclerosis versus Multifocal Motor Neuropathy: Utility of MR Neurography

Background Differential diagnosis between amyotrophic lateral sclerosis (ALS) and multifocal motor neuropathy (MMN) relies on clinical examination and electrophysiological criteria. Peripheral nerve imaging might assist this differential diagnosis. Purpose To assess diagnostic accuracy of MR neurography in the differential diagnosis of ALS and MMN. Materials and Methods This prospective study was conducted between December 2015 and April 2017. Study participants with ALS or MMN underwent MR neurography of the lumbosacral plexus, midthigh, proximal calf, and midupper arm of the clinically more affected side using high-resolution T2-weighted sequences. Matched healthy study participants who underwent MR neurography served as a control group. Two blinded readers independently rated fascicular lesions and muscle denervation signs on a five-point scale and made an image-only diagnosis, which was compared with the clinical diagnosis to assess diagnostic accuracy (reported for ALS vs non-ALS and MMN vs non-MMN). The Kruskal-Wallis test was used to compare readers' scoring results. Results Twenty-two participants with ALS (12 men and 10 women; mean age ± standard deviation, 62.3 years ± 9.0), eight participants with MMN (seven men and one woman; mean age, 57.6 years ± 18.6), and 15 healthy participants (seven men and eight women; mean age, 59.1 years ± 10.9) were enrolled in this study. Nerves of participants with ALS either appeared normal or showed T2-weighted hyperintensities without fascicular enlargement (reader 1, 22 of 22 participants; reader 2, 21 of 22 participants). In contrast, nerves in MMN were characterized by fascicular swellings (reader 1, six of eight participants; reader 2, seven of eight participants). Muscle denervation signs were more prominent in ALS than in MMN. Inter-rater reliability for blinded diagnosis was κ of 0.82. By consensus, the sensitivity to diagnose ALS (vs MMN and healthy control participants) was 19 of 22 (86% [95% confidence interval {CI}: 67%, 95%]). The corresponding specificity was 23 of 23 (100% [95% CI: 86%, 100%]). The sensitivity to diagnose MMN (vs ALS and healthy control participants) was seven of eight (88% [95% CI: 53%, 99%]). The corresponding specificity was 37 of 37 (100% [95% CI: 91%, 100%]). Conclusion MR neurography is an accurate method for assisting in the differential diagnosis of amyotrophic lateral sclerosis and multifocal motor neuropathy. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Andreisek in this issue.

Ultrasonography and electrophysiological study of median nerve in patients with essential tremor

Essential tremor (ET) is a common movement disorder characterized by postural or kinetic tremor. We aimed to evaluate median nerve enlargement in patients with ET using ultrasonography (USG). Thirty-eight hands from 19 patients with ET and 24 hands from 13 controls underwent nerve conduction studies (NCS) and USG at the wrist. Tremor severity was measured using the Fahn-Tolosa-Marin Tremor Rating Scale (FTM-TRS). The median nerve cross sectional area (mCSA) in USG and NCS parameters were compared using ANCOVA. We evaluated the correlation between mCSA and NCS parameters or FTM-TRS scores using linear regression analysis. mCSA was significantly larger (p<0.001) and NCS parameters were different in two groups. Also, mCSA was negatively correlated with part B and C scores of FTM-TRS (p<0.001 and p = 0.039, respectively). In conclusion, median nerve enlargement with the changes of NCS parameters was observed and correlated with the severity of tremor in patients with ET.

Ultrasonographic measurement of the cross-sectional area of the axillary nerve

INTRODUCTION

The objectives of this study were to determine normal reference values for ultrasonographic measurement of the cross-sectional area (CSA) of the axillary nerve and to standardize the measurement methods.

METHODS

Sixty healthy volunteers were evaluated. Ultrasonography was performed with the shoulder positioned in 100°-120° abduction and 90° external rotation. The CSA of the axillary nerve was measured bilaterally.

RESULTS

The normal CSA of the right axillary nerve was 2.9 ± 1.1 mm² . The side-to-side discrepancy was 22.8% ± 17.8%.

DISCUSSION

These reference values may be helpful for investigating pathologies involving the axillary nerve.

Ultrasound in the Evaluation of Radial Neuropathies at the Elbow

There are five sites at which radial nerve entrapment at the elbow has been commonly reported. These include the level of the fibrous bands within the extensor carpi radialis brevis, the thickened fascial tissue at the radiocapitellar joint, the leash of Henry, the arcade of Frohse, and the distal border of the supinator muscle. This review describes the anatomy of the radial nerve at the elbow and the surrounding structures, and then provides an overview of the literature supporting the use of ultrasound to assist in the evaluation of suspected radial neuropathy at the elbow. This review concludes with a suggested ultrasonographic approach for the systematic evaluation of suspected radial neuropathy at the elbow.

Ultrasound-Derived Nerve Cross-Sectional Area in Extremes of Height and Weight

BACKGROUND AND PURPOSE

There is a lack of consensus in the literature as to which body habitus parameter most influences nerve cross-sectional area (CSA). This study was specifically designed to determine if height or weight is more influential.

METHODS

Fifteen young healthy participants, 8 extremely tall and 7 heavy, with no peripheral nerve symptoms were recruited. The tall cohort consisted of males who were 74 inches or taller and females who were 68 inches or taller. The heavy cohort consisted of males who were 274 lbs or heavier and females who were 200 lbs or heavier. Measurements were obtained bilaterally at 7 sites using neuromuscular ultrasound: median nerve at the wrist and mid-forearm, ulnar at the elbow, radial at the spiral groove, fibular at the knee, tibial at the ankle, and sural at the ankle. The nerve CSA at each site was measured by tracing of the nerve using the "freehand" trace function of the ultrasound device.

RESULTS

Weight tightly correlated with nerve CSA (R² = .69, P < .001), while height did not significantly predict CSA (R² = .10, P = .244). Nerve CSA for tall participants did not systematically deviate from an historical control group. Conversely, with exception of the tibial and sural nerves at the ankle, all nerve CSAs for heavy participants were higher than in the control group.

CONCLUSION

Weight was found to be the body habitus parameter that most influences nerve CSA. This will inform clinicians when using nerve imaging to evaluate participants at either extreme of weight.