Evaluation Of freehand high‐resolution 3‐dimensional ultrasound of the median nerve

Introduction: In this study we evaluated freehand 3D ultrasound (3DUS) of the median nerve in comparison to 2D ultrasound (2DUS) and assessed the influence of tilting the transversal plane on cross‐sectional area (CSA) measurement. Methods: Two examiners investigated the median nerves of 22 healthy subjects over a distance of 20 cm using 3DUS. Image quality and CSA were assessed at random points within the virtual 3D volume and compared with 2DUS. Results: Image quality within the virtual 3D volume was good/sufficient/poor in 53.0%/40.2%/6.8% (examiner 1) and 21.6%/69.6%/8.8% (examiner 2), respectively. CSA measurements with 3DUS were smaller than with 2DUS (–12% and –17%; Wilcoxon test, P < 0.001). Interrater agreement for 3DUS and intermethod agreement between 2DUS and 3DUS were moderate. Stepwise tilting of the transversal plane increased CSA significantly. Conclusion: Freehand 3DUS of the median nerve over 20 cm is feasible and may help overcome some of the limitations and pitfalls of 2DUS. Muscle Nerve 55 : 206–212, 2017     

Visualization of the diaphragm muscle with ultrasound improves diagnostic accuracy of phrenic nerve conduction studies

Introduction: Evaluation of phrenic neuropathy (PN) with phrenic nerve conduction studies (PNCS) is associated with false negatives. Visualization of diaphragmatic muscle twitch with diaphragm ultrasound (DUS) when performing PNCS may help to solve this problem. Methods: We performed bilateral, simultaneous DUS–PNCS in 10 healthy adults and 12 patients with PN. The amplitude of the diaphragm compound muscle action potential (CMAP) (on PNCS) and twitch (on DUS) was calculated. Results: Control subjects had <38% side‐to‐side asymmetry in twitch amplitude (on DUS) and 53% asymmetry in phrenic CMAP (on PCNS). In the 12 patients with PN, 12 phrenic neuropathies were detected. Three of these patients had either significant side‐to‐side asymmetry or absolute reduction in diaphragm movement that was not detected with PNCS. There were no cases in which the PNCS showed an abnormality but the DUS did not. Conclusions: The addition of DUS to PNCS enhances diagnostic accuracy in PN. Muscle Nerve 49 : 669–675, 2014     

High‐resolution ultrasound visualization of the subcutaneous nerves of the forearm: A feasibility study in anatomic specimens

Introduction: The aim of this ultrasound‐anatomical study was to evaluate the ability of high‐resolution ultrasound (HRUS) to visualize and infiltrate small subcutaneous nerves of the forearm in anatomic specimens. Methods: Seven nonembalmed human bodies (4 men, 3 women; mean age at death, 60 years) were included in the study. Two investigators scanned the anatomic specimens using 15‐MHz and 18‐MHz HRUS transducers. The lateral, medial, and posterior antebrachial cutaneous nerves were scanned and interventionally marked with ink using HRUS‐guidance. Subsequently, dissections were performed to assess the anatomical correlation of HRUS findings. Results: All 3 nerves were identified consistently using HRUS. The precision of the ink‐markings was excellent, with good correlation with the small peripheral branches of all 3 nerves. Conclusions: HRUS can identify precisely the small subcutaneous nerves of the forearm and may aid in both diagnosis and therapy in cases of neuropathy. Muscle Nerve 49 : 676–679, 2014     

Diagnostic ultrasound for nerve transection

The current approach for localizing and assessing the severity of traumatic peripheral nerve injuries involves clinical evaluation and electrodiagnostic studies. However, the ability of this approach to determine the extent of nerve damage within the first 6 weeks after trauma is limited. This is problematic because outcome is improved with early surgical intervention after complete nerve transection. This led us to explore alternative techniques, such as imaging, for assessing peripheral nerve injuries. Twelve fresh cadavers were obtained and after inspection 20 arms were deemed suitable for inclusion in the study. Random sites were transected in median, ulnar, and radial nerves, and sham skin incisions were performed throughout the arm. These nerves were then systematically scanned by an ultrasonographer blinded to the nerve transection sites, who made a final decision as to whether the nerve was transected. High-resolution ultrasound was able to identify transected nerves in the upper extremity with 89% sensitivity and 95% specificity in fresh cadavers. This proof-of-concept study shows that ultrasound can accurately identify nerve transection, which should lead to further ultrasound studies in patients with traumatic peripheral nerve injuries.     

B超在诊治桡神经卡压综合征中的应用

目的探讨B超在诊治桡神经卡压综合征中的应用效果。方法选取我院收治的上臂桡神经卡压综合征患者28例为研究对象,所有患者采用B超和肌电图诊断上臂桡神经,比较B超和肌电图诊断结果,根据B超诊断结果对患者实施针对性治疗,并将术后证实结果与B超诊断结果进行比较。结果 B超影像显示患者侧桡神经直径和横截面积明显高于健康侧桡神经直径和横截面积,同时B超诊断结果与术后证实结果相同。结论采用B超检查上臂桡神经卡压综合征,能正确定位卡压部位、显示卡压原因,为上臂桡神经的治疗提供科学参考依据。     

Cross-sectional area reference values for nerve ultrasonography

Ultrasound allows for a non-invasive structural assessment of nerves, muscles, and surrounding tissues, and therefore it is increasingly being used as a supplement to traditional electrodiagnostic studies. As investigators have begun to use ultrasound to explore peripheral nerves, it has become clear that conditions such as entrapment, hereditary neuropathies, acquired neuropathies, trauma, and nerve tumors result in an increase in nerve cross-sectional area. Reference values have not been published for the cross-sectional area of many nerves commonly studied in diseases of the peripheral nervous system, so our goal was to obtain reference values for the nerve cross-sectional area at the following sites: radial at antecubital fossa; radial at distal spiral groove; musculocutaneous in upper arm; trunks of the brachial plexus; vagus at carotid bifurcation; sciatic in distal thigh; tibial in popliteal fossa; tibial in proximal calf; tibial at ankle; peroneal in popliteal fossa; peroneal at fibular head; and sural in distal calf. Mean cross-sectional area, as well as side-to-side differences, are reported for each site, and qualitative data are provided to guide imaging at each site. The information provided in this study should serve as the starting point for quantitatively evaluating these nerve sites with ultrasound.     

Guidelines for neuromuscular ultrasound training

Neuromuscular ultrasound has become an essential tool in the diagnostic evaluation of various neuromuscular disorders, and, as such, there is growing interest in neuromuscular ultrasound training. Effective training is critical in mastering this modality. Our aim was to develop consensus-based guidelines for neuromuscular ultrasound training courses. A total of 18 experts participated. Expert opinion was sought through the Delphi method using 4 consecutive electronic surveys. A high degree of consensus was achieved with regard to the general structure of neuromuscular ultrasound training; the categorization of training into basic, intermediate, and advanced levels; the learning objectives; and the curriculum for each level. In this study, a group of neuromuscular ultrasound experts established consensus-based guidelines for neuromuscular ultrasound training. These guidelines can be used in the development of the specialty and the standardization of neuromuscular ultrasound training courses and workshops.     

Sonographic measurements of longitudinal median nerve sliding in patients following nerve repair

Nerve sliding may be restricted following nerve repair. This could result in increased tension across the repair site and lead to poor functional recovery of the nerve. Ultrasound was used to examine longitudinal median nerve sliding in 10 patients who had previously undergone nerve repair surgery following complete division of the median nerve. The median longitudinal movement in the forearm in response to metacarpophalangeal (MCP) joint movements was 2.15 mm on the injured side, compared with 2.54 mm on the uninjured side, a difference that was significant. There was a significant reduction in nerve sliding following repair (median = 8%, range ?8% to 54%; P = 0.02), which correlated with time from injury to surgery (rho = 0.87; P = 0.001). These results indicate that ultrasound can be used as an adjunct assessment tool to monitor both morphology and sliding of the nerve through the repair site. It may have future application in the investigation of patients with persisting functional impairment following primary nerve repair. Muscle Nerve, 2009     

Peripheral nerve ultrasound in amyotrophic lateral sclerosis phenotypes

Introduction: In this study we sought to determine the cross‐sectional area (CSA) of peripheral nerves in patients with distinct subtypes of amyotrophic lateral sclerosis (ALS). Methods: Ulnar and median nerve ultrasound was performed in 78 ALS patients [classic, n = 21; upper motor neuron dominant (UMND), n = 14; lower motor neuron dominant (LMND), n = 20; bulbar, n = 15; primary lateral sclerosis (PLS), n = 8] and 18 matched healthy controls. Results: Compared with controls, ALS patients had significant, distally pronounced reductions of ulnar CSA (forearm/wrist level) across all disease groups, except for PLS. Median nerve CSA (forearm/wrist level) did not differ between controls and ALS. Conclusion: Ulnar nerve ultrasound in ALS subgroups revealed significant differences in distal CSA values, which suggests it has value as a marker of LMN involvement. Its potential was particularly evident in the UMND and PLS groups, which can be hard to separate clinically, yet their accurate separation has major prognostic implications. Muscle Nerve 51 :669–675, 2015     

Ultrasound diagnosis of bony nerve entrapment: Case series and literature review

Introduction: Nerve entrapment due to osseous callus formation is a rare complication after bone fracture. Electrodiagnostic studies and routine radiographic imaging often fail to demonstrate the pathology. The diagnosis is difficult and is often made incidentally upon surgical exploration. Nerve ultrasonography has not been used routinely to assess such lesions. Methods: We report 5 cases of nerve entrapment in osseous callus after fractures that occurred in 2011 and 2012. The diagnosis was made by ultrasound (US). We then performed a review of the relevant literature. Conclusions: US is becoming an invaluable tool for diagnosing peripheral nerve entrapments. The current cases suggest that nerve US should be strongly considered as an adjunctive diagnostic tool for nerve palsies developing after trauma. Muscle Nerve 48 : 445–450, 2013     

Neuromuscular ultrasound in common entrapment neuropathies

Neuromuscular ultrasound involves the use of high‐resolution ultrasound to image the peripheral nervous system of patients with suspected neuromuscular diseases. It complements electrodiagnostic studies well by providing anatomic information regarding nerves, muscles, vessels, tendons, ligaments, bones, and other structures that cannot be obtained with nerve conduction studies and electromyography. Neuromuscular ultrasound has been studied extensively over the past 10 years and has been used most often in the assessment of entrapment neuropathies. This review focuses on the use of neuromuscular ultrasound in 4 of the most common entrapment neuropathies: carpal tunnel syndrome, ulnar neuropathy at the elbow and wrist, and fibular neuropathy at the knee. Muscle Nerve 48:696–704, 2013     

Differential age-, gender-, and side-dependency of vagus,spinal accessory,and phrenic nerve calibers detected with precise ultrasonography measures

Introduction: The standard ultrasonographic measurement tools (trace, ellipse) of cross-sectional areas (CSAs) of very small nerves typically yield rough measures in full square millimeters. Methods: In 70 volunteers, the elliptically shaped CSAs of mid-cervical vagus, accessory, and phrenic nerves were estimated with three methods: 2 on-board tools (area tracing, ellipse fitting) and an off-line calculation of the CSA after on-board measuring of its long-axis and short-axis diameters both displayed with 1-2 digits following the decimal point. Results: CSA measures of all mid-cervical nerves obtained with the precise approach were smaller than the two standard measures (each P < 0.001). Larger CSA of right compared to left vagus nerve was detected with all methods. However, decrease of accessory and phrenic nerve CSAs with increasing age and larger size of vagus nerve CSA in women vs. men were evident only with precise measures. Discussion: Small nerve CSA should preferably be estimated with precise measures. Muscle Nerve 59:486–491, 2019     

Nerve ultrasound in diabetic polyneuropathy: Correlation with clinical characteristics and electrodiagnostic testing

Introduction: Diabetic polyneuropathy (DPN) is increasingly prevalent in the USA, but nerve ultrasound (US) findings have not been assessed systematically. Our aim was to establish the sonographic characteristics of lower extremity nerves in DPN and correlate them with electrodiagnostic (EDx) findings. Methods: Consecutive patients (n = 25) with evidence of DPN and 25 patient controls without DPN underwent blinded US imaging of the fibular and sural nerves. Nerve cross‐sectional area (CSA), diameter and echogenicity were recorded. Results: There were no differences in fibular or sural nerve CSA, diameter, or echogenicity between the 2 groups. No correlations between nerve CSA and EDx studies were found. In DPN, there were moderate inverse correlations with age (r = ?0.44 sural ankle, r = ?0.39 sural leg, r = ?0.45 fibular ankle). Conclusions: US measurements of lower extremity nerves in DPN do not differ from controls or correlate with EDx findings. Novel US techniques and/or pedal nerve US may be necessary to detect differences. Muscle Nerve 47:379‐384, 2013     

Nerve ultrasound in electrophysiologically verified tarsal tunnel syndrome

Introduction: Tarsal tunnel syndrome (TTS) arises from tibial nerve damage under the flexor retinaculum of the fibro‐osseus tunnel at the medial malleolus. It is notoriously difficult to diagnose, as many other foot pathologies result in a similar clinical picture. We examined the additional value of nerve ultrasound in patients with tarsal tunnel syndrome confirmed by nerve conduction. Methods: We performed a retrospective analysis of nerve ultrasound changes in electrophysiologically confirmed TTS spanning our records from 2007 to 2015. Results: Nine feet with TTS were identified, all of which showed abnormal nerve ultrasound findings, which in 6 feet, led to identification of the underlying cause. Conclusions: This study shows that nerve ultrasound is abnormal in all cases of electrophysiologically verified TTS. The pattern of nerve abnormality is varied. This, and the fact that in the majority of patients causation was identified, suggests nerve ultrasound should form part of standard work‐up for TTS. Muscle Nerve 53 : 906–912, 2016