Ultrasonography of Peripheral Nerves

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.

Non-glandular findings on breast ultrasound. Part II: a pictorial review of chest wall lesions

The breast ultrasound (US) field-of-view (FOV) includes glandular parenchyma as well as tissues located anterior to and posterior to it, up to pleural line. For that, it is possible to incidentally identify lesions unrelated to breast parenchyma during screening or diagnostic US; sometimes a palpable lump may be the reason of the imaging exam. Furthermore, abnormality related to chest wall are easier and more accurate detected after mastectomy. Hence, radiologists should know the US appearance of lesions which may develop from all tissues present in this region and displayed in the US FOV, without focusing only on glandular abnormalities while performing the exam. This is the second of a two-part series on non-glandular breast lesions; in detail, part two provide an overview of US appearance, differential diagnosis, and pitfalls of chest wall lesions. They may have an infectious, traumatic, inflammatory etiology or be benign or malignant neoplasms. The US role in the assessment of chest wall abnormalities is limited, usually computed tomography and/or magnetic resonance are requested as second-level imaging exams to characterize and to assess better their relationship with surrounding structures because of larger and panoramic view. Finally, US could be useful to guide biopsy.

Silent peripheral neuropathy determined by high-resolution ultrasound among contacts of patients with Hansen's disease

Introduction

Hansen's disease (HD) primarily infects peripheral nerves, with patients without HD being free of peripheral nerve damage. Household contacts (HHCs) of patients with HD are at a 5-10 times higher risk of HD than the general population. Neural thickening is one of the three cardinal signs that define a case of HD according to WHO guidelines, exclusively considering palpation examination that is subjective and may not detect the condition in the earliest cases even when performed by well-trained professionals. High-resolution ultrasound (HRUS) can evaluate most peripheral nerves, a validated technique with good reproducibility allowing detailed and accurate examination.

Objective

This study aimed to use the peripheral nerve HRUS test according to the HD protocol as a diagnostic method for neuropathy comparing HHCs with healthy volunteers (HVs) and patients with HD.

Methods

In municipalities from 14 different areas of Brazil we selected at random 83 HHC of MB-patients to be submitted to peripheral nerve ultrasound and compared to 49 HVs and 176 HD-patients.

Results

Household contacts assessed by HRUS showed higher median and mean absolute peripheral nerve cross-sectional area (CSA) values and greater asymmetries (ΔCSA) compared to HVs at the same points. Median and mean absolute peripheral nerve CSA values were higher in patients with HD compared to HCCs at almost all points, while ΔCSA values were equal at all points. Mean ± SD focality (ΔTpT) values for HHCs and patients with HD, respectively, were 2.7 ± 2.2/2.6 ± 2.2 for the median nerve, 2.9 ± 2.7/3.3 ± 2.9 for the common fibular nerve (p > 0.05), and 1.3 ± 1.3/2.2 ± 3.9 for the ulnar nerve (p < 0.0001).

Discussion

Considering HRUS findings for HHCs, asymmetric multiple mononeuropathy signs (thickening or asymmetry) in at least 20% of the nerves evaluated could already indicates evidence of HD neuropathy. Thus, if more nerve points are assessed in HHCs (14 instead of 10), the contacts become more like patients with HD according to nerve thickening determined by HRUS, which should be a cutting-edge tool for an early diagnosis of leprosy cases.

Point-of-care ultrasound of peripheral nerves in the diagnosis of Hansen's disease neuropathy

Introduction

Hansen's disease (HD) is the most common cause of treatable peripheral neuropathy in the world that may or may not involve skin manifestations, and physical examination based on simplified neurologic evaluation is a subjective and inaccurate procedure. High-resolution ultrasound (HRUS) can be used to evaluate peripheral nerves and is a validated technique of good reproducibility, permitting a detailed and precise examination.

Objectives

We proposed to establish objective criteria for absolute values of the measurement of the CSA of peripheral nerves and their indices of the ΔCSA and ΔTpT in the diagnosis of Hansen's disease neuropathy as compared with healthy voluntaries.

Materials and methods

In municipalities from different regions of Brazil, we randomly selected 234 volunteer Brazilian patients diagnosed with leprosy to be submitted to peripheral nerve echography and compared with 49 healthy Brazilian volunteers.

Results

Hansen Disease assessed by high resolution ultrasound is a primarily neural disease that leads to multiple hypertrophic mononeuropathy characterized by CSA values exceeding normal limits (Med CT = 10.2 mm²; UT = 9.8 mm²; UPT = 9.3 mm²; CFFH = 18.3 mm²; T = 9.6 mm²), and the pattern of asymmetry (ΔCSA>2.5 mm² with RR 13) and focality (ΔTPT > 2.5 mm² with RR 6.4) of this thickening has higher sensitivity (76,1%) and specificity (87,8 %) for its early diagnosis that laboratory tests. Analyzing each subject, the percentage of thickened nerves detected among the total number of nerves assessed was higher among patients with HD than among healthy individuals (p < 0.0001). Individuals with two or more thickened nerves were at 24.1 times higher relative risk (95% CI: 6.74–88.98) of HD.

Ultrasound reference values for peripheral nerve cross-sectional areas and indices in a sample of healthy individuals in Brazil

Objective

To establish peripheral nerve cross-sectional area (CSA) reference values (absolute values, measures of asymmetry, and measures of focality) for healthy individuals in Brazil.

Materials and Methods

Sixty-six healthy volunteers underwent high-resolution ultrasound of the peripheral nerves. We obtained CSA measurements for three peripheral nerves, at specific locations: the median nerve, in the carpal tunnel (MT); the ulnar nerve, at the cubital tunnel site (UT) and at the pre-tunnel site (UPT); and the common fibular nerve, near the fibular head (FH). We calculated the CSA indices between the same sites on different sides (ΔCSAs) and between the ulnar nerve tunnel and pre-tunnel sites on the same side (ΔTPT).

Results

A total of 132 neural sites were analyzed, and the following CSA values (mean ± SD, median) were obtained: MT (6.3 ± 1.9 mm², 6.0 mm²); UT (6.2 ± 1.6 mm², 6.1 mm²); UPT (5.6 ± 1.7 mm², 5.4 mm²); and FH (10.0 ± 3.7 mm², 9.9 mm²). The ΔCSA values (mean ± SD, median) were as follows: MT (0.85 ± 0.7 mm², 0.95); UT (0.81 ± 0.62 mm², 0.95); UPT (0.61 ± 0.51 mm², 0.5); and FH (1.0 ± 0.77 mm², 1.0). The ΔTPT (mean ± SD, median) was (1.0 ± 0.8 mm², 1.0).

Conclusion

Among individuals in Brazil, peripheral nerve CSA values tend to be higher among males and to increase with aging. However, the same does not appear to hold true for the ΔCSA or the ΔTPT, the exception being the difference between the right and left UT. Differences in CSA values greater than 2.5 mm² between sides or between sites along the same nerve can indicate asymmetry or focal thickening in neuropathy, respectively.

Hand and Wrist Neuropathies: High-resolution Ultrasonography and MR Neurography

High-resolution ultrasonography (US) and magnetic resonance neurography (MRN) have followed parallel paths for peripheral nerve imaging with little comparison of the two modalities. They seem equally effective to study a variety of neuropathies affecting large and small nerves in the wrist and hand. This article outlines the technical considerations of US and MRN and discusses normal and abnormal imaging appearances of hand and wrist nerves from etiologies such as entrapment, injury, tumor, and proximal and diffuse neuropathy, with specific case illustrations.

Treatment of meralgia paresthetica (Lateral Femoral Cutaneous Neuropathy): A meta-analysis of ultrasound-guided injection versus surgery

PURPOSE

To compare ultrasound (US)-guided injections and surgery for the treatment of meralgia paresthetica (lateral femoral cutaneous neuropathy).

METHODS

Two reviewers, independently, up to 10 October 2020 retrieved Studies that assessed the outcome of US-guided injections and surgery for the treatment of meralgia paresthetica from major medical libraries. Predefined inclusion and exclusion criteria were adopted.

RESULTS

399 studies were initially found, and the meta-analysis was conducted on 10 studies for a total of 149 patients. US-guided injections were done in three studies, surgery in seven studies. N = 38 % (57/149) of patients were treated with US-guided injection and 62 % (92/149) were treated with surgery. After US-guided injections, 85 % (49/57) of patients were treated successfully, whereas 80 % (74/92) were treated with surgery successfully from the clinical point of view. Differences were not statistically significant even with a slight heterogeneity of studies and outcome pooled on random-effect model. No comparative cohort study or RCT was conducted.

CONCLUSION

This meta-analysis showed that there was no statistically significant difference in treatment of meralgia paresthetica with ultrasound-guided injection or surgery. A RCT to compare a standardized US-guided approach versus surgery is essential to compare these techniques properly.

Role of nerve ultrasound versus electrophysiological studies in the evaluation of nerve injuries

Background

High-resolution ultrasonography (US) is a non-invasive, readily applicable imaging modality capable of depicting real-time static and dynamic information concerning the peripheral nerves and their surrounding tissues. Although electrophysiological studies are the gold standard in the evaluation of nerve injuries, US can be used also to evaluate the morphological changes of nerve injuries.

Objectives

To evaluate the role of the high-resolution US in the assessment of nerve injuries and to compare it to the role of electrodiagnostic studies.

Subjects and methods

A total of 30 nerves from 22 consecutive patients with clinically definite nerve injury were considered. Two independent and blinded clinicians perform electrodiagnosis and US. The clinical, neurophysiological, and US findings were collected, and the contribution of US was then classified as “ contributive” or “non-contributive”, according to whether US confirmed the clinical and neurophysiological diagnosis or not.

Results

US was “contributive” (confirming the electrophysiological diagnosis) in 66.67% of cases (n = 20), providing information about continuity of the nerve, morphological changes after injury as swelling, scar tissue formation, or neuroma formation with sensitivity of 75% compared to the electrodiagnostic studies and accuracy of 66.67%.

Conclusion

Ultrasound can be used, when available, as a complementary tool for electrodiagnostic studies to provide anatomical information about the injured nerves in case of complete axonal lesion.

Peripheral nerve imaging: Not only cross-sectional area

Peripheral nerve imaging is recognized as a complement to clinical and neurophysiological assessment in the evaluation of peripheral nerves with the ability to impact patient management, even for small and difficult nerves. The European Society of Musculoskeletal Radiology, suggest to use ultrasound (US) for nerve evaluation due to the fact that, in sever anatomical area, magnetic resonance imaging is not able to give additional informations. US could be considered the first-choice approach for the assessment of peripheral nerves. The relative drawback of peripheral nerve US is the long learning curve and the deep anatomic competence to evaluate even small nerves. In the recent years, the role of US in peripheral nerve evaluation has been widened. In the past, nerve US was mainly used to assess nerve-cross sectional area, but now more advanced measurements and considerations are desirable and can boost the role of peripheral nerve US. Nerve echotexture evaluation was defined in 2010: The ratio between the hypoechoic and hyperechoic areas of peripheral nerves on US was called “nerve density”. For evaluation of patients who have peripheral neuropathies, the role of peripheral nerve is US wider than simple cross-sectional area evaluation. Quantitative measurements describing the internal fascicular echotexture of peripheral nerves introduce the concept of considering US as a possible quantitative imaging biomarker technique. The potential of nerve US has started to be uncovered. It seems clear that only cross-sectional area measurement is no more sufficient for a comprehensive US evaluation of peripheral nerves.