Neuromuscular ultrasound in common entrapment neuropathies

Peroneal Nerve Entrapment in Diabetes Mellitus

This narrative mini-review discusses the association between peroneal nerve entrapment (PEN) and diabetes mellitus (DM). Generally, PEN is not a common cause of peripheral neuropathy in DM. Poor glycaemic control and DM duration are powerful risk factors for PEN. Underlying mechanisms involve neurodegeneration and entrapment of the peroneal nerve. Patients tend to present with chronic leg pain, gradual foot drop, steppage gait, or weakness of ankle dorsiflexion. Electrodiagnostic and imaging studies are very useful in diagnosis to determine the level at which entrapment occurs. Treatment varies based on the aetiology and severity of symptoms. It is initially conservative. Surgical nerve decompression management is required when entrapment is refractory to non-operative options.

Advances in Imaging of Compressive Neuropathies

Ultrasound and magnetic resonance neurography are useful modalities to aid in the assessment of compressive neuropathies, although they are still limited in their resolution of nerve microstructure and their capacity to monitor postoperative nerve recovery. Optical coherence tomography, a preclinical imaging modality, is promising in its ability to better identify structural and potential physiologic changes to peripheral nerves, but requires additional testing and research prior to widespread clinical implementation. Further advances in nerve imaging may elucidate the ability to visualize the zone of nerve injury intraoperatively, monitor the progression of nerve regeneration, and localize problems during nerve recovery.

Median nerve ultrasonography in Parkinson's disease: a systematic review and meta-analysis

BACKGROUND

The cross-sectional area (CSA) of the median nerve in Parkinson's disease remains unclear.

OBJECTIVES

This meta-analysis assesses median nerve CSA changes in Parkinson's using ultrasonography.

METHODS

PubMed, Web of Science, Scopus, and EBSCO were selectively searched for literature on Parkinson's disease, Median nerve, and ultrasonography. Following full-text screening, three studies were included in this meta-analysis with 144 Parkinson's disease patients and 127 controls. The primary outcome was the cross-sectional area of the median nerve; other motor parameters were also evaluated.

RESULTS

The cross-sectional area of the median nerve was significantly increased in Parkinson's patients compared to controls (p = 0.007); the standardized mean difference was 0.79 [95% CI (0.21 - 1.37)]. The standardized mean difference of the motor parameters of the median nerve, amplitude, and latency was -0.04 [95% CI (-0.85 to 0.77)] and 0.30 [95% CI (-0.04 to 0.64)], respectively, with statistically insignificant (All p > 0.05).

CONCLUSION

This meta-analysis concluded that the cross-sectional area of the median nerve is increased in Parkinson's disease patients. The increase in the CSA of the median nerve might explain the higher prevalence of carpal tunnel syndrome in Parkinson's disease. Further studies are needed to quantify carpal tunnel syndrome prevalence accurately in Parkinson's.

LIMITATIONS

Heterogeneity exists due to non-standardized CSA calculation methods and varied disease stages. Finger movement during ultrasound may introduce artifacts, compromising CSA measurement accuracy. Establishing a definitive CSA cut-off for carpal tunnel syndrome in Parkinson's requires further investigation.

Ultrasonographic Contrast and Therapeutic Effects of Hydrogen Peroxide-Responsive Nanoparticles in a Rat Model with Sciatic Neuritis

Purpose

Peripheral nerve damage lacks an appropriate diagnosis consistent with the patient's symptoms, despite expensive magnetic resonance imaging or electrodiagnostic assessments, which cause discomfort. Ultrasonography is valuable for diagnosing and treating nerve lesions; however, it is unsuitable for detecting small lesions. Poly(vanillin-oxalate) (PVO) nanoparticles are prepared from vanillin, a phytochemical with antioxidant and anti-inflammatory properties. Previously, PVO nanoparticles were cleaved by H2O2 to release vanillin, exert therapeutic efficacy, and generate CO2 to increase ultrasound contrast. However, the role of PVO nanoparticles in peripheral nerve lesion models is still unknown. Herein, we aimed to determine whether PVO nanoparticles can function as contrast and therapeutic agents for nerve lesions.

Methods

To induce sciatic neuritis, rats were administered a perineural injection of carrageenan using a nerve stimulator under ultrasonographic guidance, and PVO nanoparticles were injected perineurally to evaluate ultrasonographic contrast and therapeutic effects. Reverse transcription-quantitative PCR was performed to detect mRNA levels of pro-inflammatory cytokines, ie, tumor necrosis factor-α, interleukin-6, and cyclooxygenase-2.

Results

In the rat model of sciatic neuritis, PVO nanoparticles generated CO2 bubbles to increase ultrasonographic contrast, and a single perineural injection of PVO nanoparticles suppressed the expression of tumor necrosis factor-α, interleukin-6, and cyclooxygenase-2, reduced the expression of F4/80, and increased the expression of GAP43.

Conclusion

The results of the current study suggest that PVO nanoparticles could be developed as ultrasonographic contrast agents and therapeutic agents for nerve lesions.

Neuromuscular ultrasound: Impact on diagnosis and management

INTRODUCTION/AIM

High-resolution ultrasound (HRUS) is increasingly used in evaluating neuromuscular conditions. Its potential advantages include its ability to discern anatomic information and make specific etiological diagnoses. Although many studies have demonstrated HRUS effectiveness, especially in mononeuropathies, more information is needed to better determine how often and to what extent useful information is obtained; how it influences diagnosis, clinical decision-making, and patient management; and how it is used with electrodiagnostic (EDx) studies.

METHODS

A retrospective cohort study was performed on patients referred for HRUS at a university laboratory during 2021. Demographic information, referral diagnoses, clinical information, HRUS findings, and follow-up patient management were analyzed. For patients who had EDx, results were compared with HRUS. Determinations were made whether HRUS did or did not aid in the diagnosis. For patients in whom HRUS resulted in a diagnosis, determination was made whether it confirmed the diagnosis made clinically or by EDx but did not change management; added additional important information; and/or made a decisive impact on subsequent management.

RESULTS

Five hundred two patients were analyzed, most referred for mononeuropathy, brachial plexopathy, and polyneuropathy. HRUS was abnormal in 81.7% of patients. HRUS added additional useful information in 79.0% and was decisive in management in 62.7%. In patients who also had abnormal EDx, HRUS resulted in decisive management in 49.5%.

DISCUSSION

HRUS is an effective diagnostic tool that frequently adds localizing and structural information that is otherwise not obtainable by clinical and EDx evaluation. In a substantial number of patients selected for HRUS, it is decisive in guiding further management.

The role of imaging in focal neuropathies

Electrodiagnostic testing (EDX) has been the diagnostic tool of choice in peripheral nerve disease for many years, but in recent years, peripheral nerve imaging has been used ever more frequently in daily clinical practice. Nerve ultrasound and magnetic resonance (MR) neurography are able to visualize nerve structures reliably. These techniques can aid in localizing nerve pathology and can reveal significant anatomical abnormalities underlying nerve pathology that may have been otherwise undetected by EDX. As such, nerve ultrasound and MR neurography can significantly improve diagnostic accuracy and can have a significant effect on treatment strategy. In this chapter, the basic principles and recent developments of these techniques will be discussed, as well as their potential application in several types of peripheral nerve disease, such as carpal tunnel syndrome (CTS), ulnar neuropathy at the elbow (UNE), radial neuropathy, brachial and lumbosacral plexopathy, neuralgic amyotrophy (NA), fibular, tibial, sciatic, femoral neuropathy, meralgia paresthetica, peripheral nerve trauma, tumors, and inflammatory neuropathies.

Ultrasound of the Median Nerve in the Surgical Treatment of Severe Carpal Tunnel Syndrome

BACKGROUND

High-resolution ultrasound (HRU) has demonstrated utility in the diagnosis and treatment of carpal tunnel syndrome (CTS) by measuring the cross-sectional area (CSA) of the median nerve. We investigated whether HRU could be helpful in evaluating outcomes of carpal tunnel release in patients with severe CTS.

METHODS

Patients greater than 18 years of age with severe CTS on electrodiagnostic (EDX) studies and scheduled to have carpal tunnel release were enrolled. At baseline visit within 6 weeks preoperatively, HRU was used to measure median nerve CSA at the carpal tunnel inlet and forearm, and the wrist/forearm ratio (WFR) was calculated. Patients also completed the Boston Carpal Tunnel Questionnaire (BCTQ). Ultrasound and BCTQ were repeated at 6 weeks and 6 months postoperatively.

RESULTS

Twelve patients completed the study (average age, 69 years; range, 52-80 years). The WFR improved significantly at 6 weeks and reached normal levels at 6 months. The CSA at the wrist also improved at 6 months, although this did not reach statistical significance (P = .059). Boston Carpal Tunnel Questionnaire symptoms and function scores improved significantly at 6 weeks and 6 months.

CONCLUSIONS

High-resolution ultrasound provides an objective assessment of surgical outcomes in cases of severe CTS, demonstrating normalization of WFR in our series of successful cases. Future study of poor outcomes may help determine whether improvement in WFR and CSA can provide reassurance and support for observation rather than reoperation. Ultrasound also provides anatomical evaluation and may be helpful in cases with medicolegal or psychosocial issues while potentially being less costly and better tolerated than EDX or magnetic resonance imaging.

EURO-MUSCULUS/USPRM Dynamic Ultrasound Protocols for Wrist and Hand

ABSTRACT

In this dynamic protocol, ultrasound evaluation of the wrist and hand is described using various maneuvers for relevant conditions. Scanning videos are coupled with real-time patient examination videos. The authors believe that this practical guide - prepared by the international consensus of several experts - will help musculoskeletal physicians perform a better and uniform/standard examination approach.

A Review of Upper Extremity Peripheral Nerve Injuries in Throwing Athletes

Peripheral nerve injuries in the upper extremities may be common in throwing athletes as the throwing motion places extreme stress on the dominant arm. The combination of extreme stress along with repetitive microtrauma from throwing uniquely places the throwing athlete at elevated risk of upper extremity peripheral nerve injury. However, because symptoms can be non-specific and frequent co-exist with pathology in the upper extremity, the diagnosis of peripheral nerve injury is often delayed. Diagnosis of peripheral nerve injuries may require a combination of history and physical exam, diagnostic imaging, electrodiagnostic testing, and diagnostic ultrasound guided injections. The primary management should include physical therapy focusing on throwing mechanics and kinetic chain evaluation. However, some athletes require surgical intervention if symptoms do not improve with conservative management. The purpose of this focused narrative review is to highlight upper extremity peripheral neuropathies reported in throwing athletes and to provide an overview of the appropriate clinical diagnosis and management of the throwing athlete with a peripheral nerve injury. This article is protected by copyright. All rights reserved.

Cross-sectional Area Ratio of Median-to-Ulnar and Median-to-Superficial Radial Nerve at the Wrist for Diagnosis of Carpal Tunnel Syndrome

Objectives:

This study aimed to evaluate the diagnostic properties for carpal tunnel syndrome (CTS) of the median-to-ulnar cross-sectional area ratio (MUR) and the median-to-superficial radial cross-sectional area ratio (MRR).

Methods:

A case–control study was conducted. A physiatrist, blinded to the CTS status of the subjects, assessed the cross-sectional area of the median nerve (CSA-m), MUR, and MRR at the distal wrist crease for the CTS and control groups. The relationship of CSA-m, MUR, and MRR with CTS severity was tested using Spearman’s correlation. The overall diagnostic accuracy was determined using the area under the receiver operating characteristic curve (AUC). The cut-off values to diagnose CTS were chosen to achieve similar values for sensitivity and specificity.

Results:

There were 32 hands in the CTS group and 33 hands in the control group. The correlations of CSA-m, MUR, and MRR with CTS severity were 0.66, 0.56, and 0.34, respectively. The AUCs of CSA-m, MUR, and MRR were 0.86 (95%CI: 0.77–0.95), 0.79 (0.69–0.90), and 0.69 (0.56–0.82), respectively. The cut-off values of CSA-m, MUR, and MRR were 12 mm² (sensitivity, 81.3%; specificity, 81.8%), 2.6 (sensitivity, 68.8%; specificity, 69.7%), and 10 (sensitivity, 65.6%; specificity, 63.6%), respectively.

Conclusions

: MUR and MRR had acceptable diagnostic abilities but did not show superiority over CSA-m for CTS diagnosis.

State of the Art and Advances in Peripheral Nerve Surgery

This review is intended to describe and actualize the basic knowledge of the three basic entities that affect the peripheral nerve system and can be treated by surgery: nerve trauma, chronic nerve compressions, and tumors.Regarding trauma, emphasis is given on the timing of surgery, given the fact that the moment in which the surgery is performed and the employed microsurgical reconstruction technique are the most important factors in the final result. Open lesions with associated nerve injury should be managed with an early exploration carried out before 7 days. Closed injuries are usually deferred, with few exceptions, from 3 to 6 months after the trauma.In turn, chronic compressions require an appropriate clinical, neurophysiological, and imaging diagnosis. Isolated sensory symptoms can be treated actively though without surgery: motor signs like atrophy should be regarded as a sign for immediate surgery, as a deferred treatment might cause an irreversible nerve and muscular damage. Endoscopic approaches are a valuable tool for treatment in selected neuropathies.Finally, nerve tumors demand a thorough preoperative evaluation, as benign tumors are treated in a very different way when compared to malignant lesions. Benign tumors can usually be safely and completely resected without sacrificing the nerve of origin. When malignancy is confirmed, extensive resection to optimize patient survival is the main objective, potentially at the expense of neurological function. This may then be followed by adjuvant radiation and/or chemotherapy, depending on the nature of the tumor and the completeness of resection attained. The role of nerve biopsy remains controversial, and several modern diagnostic techniques might be helpful.

Evidence-based guideline: Neuromuscular ultrasound for the diagnosis of ulnar neuropathy at the elbow

INTRODUCTION/AIMS

The purpose of this literature review is to develop an evidence-based guideline for the use of neuromuscular ultrasound in the diagnosis of ulnar neuropathy at the elbow (UNE). The proposed research question was: "In patients with suspected UNE, does ulnar nerve enlargement as measured with ultrasound accurately identify those patients with UNE?"

METHODS

A systematic review and meta-analysis was performed, and studies were classified according to American Academy of Neurology criteria for rating articles for diagnostic accuracy.

RESULTS

Based on Class I evidence in four studies, it is probable that neuromuscular ultrasound measurement of the ulnar nerve at the elbow, either of diameter or cross-sectional area (CSA), is accurate for the diagnosis of UNE.

RECOMMENDATION

For patients with symptoms and signs suggestive of ulnar neuropathy, clinicians should offer ultrasonographic measurement of ulnar nerve cross-sectional area or diameter to confirm the diagnosis and localize the site of compression (Level B).

Diagnosis of carpal tunnel syndrome in non-diabetic patients with hemodialysis using ultrasound: Is it a useful adjunctive tool?

OBJECTIVE

(1) To examine the ultrasound (US) characteristics in patients with hemodialysis-related carpal tunnel syndrome (H-CTS) and (2) to evaluate the accuracy of a proposed US parameter-dynamic ratio of median nerve-to-hamate hook distance (RMHD) in diagnosis of H-CTS.

DESIGN

A case-control study.

SETTING

In a tertiary medical center and a secondary hospital from Nov. 2017 to Mar. 2021.

PARTICIPANTS

Consecutive non-diabetes patients under hemodialysis were recruited and divided into a hemodialysis without CTS (H-Control) group and an H-CTS group. Age-matched volunteers without diabetes or upper extremity disorders were enrolled as the Control group.

INTERVENTION

Ultrasound examinations by two operators blinded to the patient's clinical information.

MAIN OUTCOME MEASURES

US parameters including cross-sectional area of the median nerve at the carpal tunnel inlet (CSA-I) and outlet (CSA-O), the flattening ratio of the median nerve at the inlet (FR-I) and outlet (FR-O), and RMHD.

RESULTS

Handedness and arteriovenous fistula showed no associations with CSA-I/O and FR-I/O. Compared with Control group (n=69), the CSA-I was significantly larger in the H-Control group (n=63) and H-CTS group (n=76) (p<0.05). There were no significant differences in the FR-I/-O among the three groups. For the second aim, in the H-CTS group(n=38), there was a significantly lower RMHD compared with both the Control (n=20) and H-Control groups (n=30) (0.1%±2.2% versus 3.5±2.3% and 3.8±1.7%, p<0.05). An RMHD cutoff value of <2.7% yielded a specificity of 80.0%, a sensitivity of 94.7%, and an overall accuracy of 88.2% in the diagnosis of H-CTS.

CONCLUSIONS

Neither CSA-I/-O or FR-I/-O have a role in the diagnosis of H-CTS. RMHD might be a useful US parameter in the diagnosis of CTS in non-diabetic patients undergoing hemodialysis.

Electrodiagnosis of Common Mononeuropathies: Median, Ulnar, and Fibular (Peroneal) Neuropathies

This article addresses common mononeuropathies seen in the electrodiagnostic laboratory. The most common mononeuropathies-median neuropathy at the wrist (carpal tunnel syndrome), ulnar neuropathy at the elbow, and fibular (peroneal) neuropathy at the fibular head-are reviewed. The causes, clinical presentations, approached to the electrodiagnostic studies (including nerve conduction studies and needle electromyography), and the typical findings are discussed.

Is Palmar Cutaneous Branch of the Median Nerve More Swollen in Carpal Tunnel Syndrome?

Objective

To investigate the characteristics of the palmar cutaneous branch of the median nerve (PCBMN) in patient with carpal tunnel syndrome (CTS) using high-resolution ultrasound.

Methods

Fourteen healthy volunteers (17 wrists) and 31 patients with CTS (41 wrists) were evaluated by high-resolution ultrasound. All patients were classified into three groups based on the electrophysiologic CTS impairment severity: mild, moderate, and severe. Using high-resolution ultrasound, the cross-sectional areas (CSAs) of the PCBMN were measured at the proximal wrist crease, bistyloid line, and distal wrist crease, and the largest CSA was defined as the maximal CSA.

Results

The maximal CSA of the PCBMN of the control, mild, moderate, and severe CTS groups were 0.27±0.08, 0.30±0.07, 0.35±0.10, and 0.47±0.13 mm², respectively. The maximal CSA of the PCBMN was significantly larger in the severe CTS group than in the other groups.

Conclusion

The PCBMN could be concomitantly affected in patients with severe CTS.

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.

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 Nerve Ultrasound Abnormalities in POEMS Syndrome-A Comparative Study

Background: High-resolution nerve ultrasound (HRUS) has been proven to be a valuable tool in the diagnosis of immune-mediated neuropathies, such as chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, M-protein, skin changes) is an important differential diagnosis of CIDP. Until now, there have been no studies that could identify specific HRUS abnormalities in POEMS syndrome patients. Thus, the aim of this study was to assess possible changes and compare findings with CIDP patients. Methods: We retrospectively analyzed HRUS findings in three POEMS syndrome and ten CIDP patients by evaluating cross-sectional nerve area (CSA), echogenicity and additionally calculating ultrasound pattern scores (UPSA, UPSB, UPSC and UPSS) and homogeneity scores (HS). Results: CIDP patients showed greater CSA enlargement and higher UPSS (median 14 vs. 11), UPSA (median 11.5 vs. 8) and HS (median 5 vs. 3) compared with POEMS syndrome patients. However, every POEMS syndrome patient illustrated enlarged nerves exceeding reference values, which were not restricted to entrapment sites. In CIDP and POEMS syndrome, heterogeneous enlargement patterns could be identified, such as inhomogeneous, homogeneous and regional nerve enlargement. HRUS in CIDP patients visualized both increased and decreased echointensity, while POEMS syndrome patients pictured hypoechoic nerves with hyperechoic intraneural connective tissue. Discussion: This is the first study to demonstrate HRUS abnormalities in POEMS syndrome outside of common entrapment sites. Although nerve enlargement was more prominent in CIDP, POEMS syndrome patients revealed distinct echogenicity patterns, which might aid in its differentiation from CIDP. Future studies should consider HRUS and its possible role in determining diagnosis, prognosis and treatment response in POEMS syndrome.

Comprehensive approaches for diagnosis, monitoring and treatment of chronic inflammatory demyelinating polyneuropathy

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is the most common chronic inflammatory neuropathy. CIDP is diagnosed according to the European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) criteria, which combine clinical features with the electrophysiological evidence of demyelination. However, firstly, diagnosis is challenging, as some patients e.g. with severe early axonal damage do not fulfil the criteria. Secondly, objective and reliable tools to monitor the disease course are lacking. Thirdly, about 25% of CIDP patients do not respond to evidence-based first-line therapy. Recognition of these patients is difficult and treatment beyond first-line therapy is based on observational studies and case series only. Individualized immunomodulatory treatment does not exist due to the lack of understanding of essential aspects of the underlying pathophysiology.

Novel diagnostic imaging techniques and molecular approaches can help to solve these problems but do not find enough implementation. This review gives a comprehensive overview of novel diagnostic techniques and monitoring approaches for CIDP and how these can lead to individualized treatment and better understanding of pathophysiology.

Clinical, Radiological, and Electrodiagnostic Diagnosis of Pronator Syndrome Concurrent With Carpal Tunnel Syndrome

PURPOSE

This is a retrospective observational study that assessed the prevalence of positive diagnostic imaging and electrodiagnostic (EDX) findings in patients diagnosed with pronator syndrome (PS), who previously had a carpal tunnel syndrome (CTS) surgery. The other purpose of our study was to determine how often PS occurred and was missed in patients treated surgically for CTS.

METHODS

The files of 180 patients who underwent CTS surgery were reviewed retrospectively. We assessed all patients for a diagnosis of PS. We accepted the clinical findings and patient history as the reference standard for the diagnosis of PS. Anteroposterior and lateral radiographs of the elbow, bilateral upper limb magnetic resonance imaging (MRI) studies, and bilateral dynamic forearm ultrasound (US) were performed on patients with clinical symptoms and physical examinations that indicated PS. Bilateral upper limb EDX was also performed for these patients. One patient refused additional tests.

RESULTS

A total of 174 extremities in 146 patients were included in the study. Pronator syndrome was diagnosed by 2 hand surgeons in 22 extremities (19 patients) through a clinical evaluation that included a history and physical examination. Diagnostic testing was positive for findings of PS in 24% of extremities (5 of 21) tested by EDX, in 57% of extremities (12 of 21) tested by US, and 5% of extremities (1 of 21) tested by MRI. There was no lower humeral spur that could cause median nerve compression on any plain radiographs.

CONCLUSIONS

With clinical evaluation as the reference standard, EDX, US, and MRI are not helpful in making a diagnosis of PS concurrent with CTS.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic IV.

Electrodiagnostic Testing of Entrapment Neuropathies: A Review of Existing Guidelines

Entrapment neuropathies cover a wide range of isolated nerve injuries along the course of the upper and lower extremity nerves. Electrodiagnostic (EDX) testing is usually an essential part of the evaluation of entrapment neuropathies, and examinations for the most common entrapment neuropathies, carpal tunnel syndrome and ulnar neuropathy at the elbow, constitute a significant part of the daily work in EDX laboratories. Despite this, guidelines for EDX testing are generally sparse or do not exist for entrapment neuropathies, whereas a wide variety of different techniques are available to the clinical neurophysiologist. This study reviews the existing, more or less, detailed EDX criteria or practice parameters that are suggested by consensus groups in peer-reviewed journals for the most common entrapment neuropathies: carpal tunnel syndrome, ulnar neuropathy at the elbow, common peroneal (fibular) neuropathy at the fibular head, and tibial neuropathy at the tarsal tunnel. It is concluded that future research is needed to develop and refine EDX guidelines in entrapment neuropathies.

Lower extremity entrapment neuropathies

Entrapment neuropathies are frequently encountered by rheumatologists, not only because they are common but also because of their association with certain rheumatological and systemic disorders. Recognizing entrapment neuropathy early can help avoid progressive neurological deficits, as well as facilitate appropriate treatment measures, which can effectively minimize a patient's symptoms. Entrapment neuropathies may be distinguished from other musculoskeletal causes of lower extremity pain by identifying characteristic patterns of weakness and/or sensory loss, so a focused bedside neurological examination is key for diagnosis. In this chapter, we review the most common entrapment neuropathies that occur in the lower extremities, review the relevant neuroanatomy, outline a diagnostic approach to distinguish them from other mimics, and highlight appropriate management options.

Peripheral Nerve Imaging Aids in the Diagnosis of Immune-Mediated Neuropathies-A Case Series

BACKGROUND

Diagnosis of immune-mediated neuropathies and their differentiation from amyotrophic lateral sclerosis (ALS) can be challenging, especially at early disease stages. Accurate diagnosis is, however, important due to the different prognosis and available treatment options. We present one patient with a left-sided dorsal flexor paresis and initial suspicion of ALS and another with multifocal sensory deficits. In both, peripheral nerve imaging was the key for diagnosis.

METHODS

We performed high-resolution nerve ultrasound (HRUS) and 7T or 3T magnetic resonance neurography (MRN).

RESULTS

In both patients, HRUS revealed mild to severe, segmental or inhomogeneous, nerve enlargement at multiple sites, as well as an area increase of isolated fascicles. MRN depicted T2 hyperintense nerves with additional contrast-enhancement.

DISCUSSION

Peripheral nerve imaging was compatible with the respective diagnosis of an immune-mediated neuropathy, i.e., multifocal motor neuropathy (MMN) in patient 1 and multifocal acquired demyelinating sensory and motor neuropathy (MADSAM) in patient 2. Peripheral nerve imaging, especially HRUS, should play an important role in the diagnostic work-up for immune-mediated neuropathies and their differentiation from ALS.

Effects of spasticity and hemiplegic posture on median nerve and carpal tunnel in stroke patients: Electrophysiological and ultrasonographic evaluation

This study aims to evaluate whether the upper extremity spasticity and hemiplegic posture have any effect on the morphology of the carpal tunnel and median nerve in stroke patients. Nerve conduction studies (NCS) were performed in 46 stroke patients and compared to those of 30 healthy controls. The cross-sectional area (CSA) of the carpal tunnel (CT) and median nerve (wrist/mid-forearm levels) was assessed by ultrasonography. The mean ages of the stroke and control group were 55.6 ± 13.5 and 56 ± 12.1 years, respectively. The median spasticity score of the forearm pronators and wrist flexor muscles was 2 (0-4) according to the Modified Ashworth Scale (MAS). The compound muscle action potential (CMAP) of the median nerve was reduced (10,093 ± 4,451 mV) when compared to non-paretic side (11,615 ± 4,397 mV) (p:0.02) and the CSA of the CT was thinner on the paretic side (1.9 ± 0.3 cm² vs 2.08 ± 0.2 cm²) (p:0.03). Pronator spasticity had no significant effect on the CSA of the median nerve and NCS at the forearm level. The CSA of the median nerve at the wrist was significantly thicker in patients with the wrist flexor spasticity graded II (MAS) and above compared to those with spasticity graded I and below (9.5 ± 1.7 mm² and 8.7 ± 1.7 mm² respectively) (p:0.03). However, the thickening of the median nerve didn't cause significant abnormalities in NCS. This study shows that in stroke patients, wrist flexor spasticity and hemiplegic wrist posture can cause explicit morphological changes in the CT and median nerve albeit normal findings on NCS.

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.

Evaluation of the Crushed Sciatic Nerve and Denervated Muscle with Multimodality Ultrasound Techniques: An Animal Study

This study was aimed at evaluating the value of multimodality ultrasound techniques in the detection of crushed sciatic nerve and denervated muscle in rabbits. Fifty healthy male New Zealand white rabbits were randomly divided into five groups (n = 10 in each group): four crushed injury groups at 1, 2, 4 and 8 wk post-sciatic nerve crushed injury, and a control group without crush injury. The crushed sciatic nerve and denervated muscle were measured with conventional ultrasound, shear wave elastography and contrast-enhanced ultrasonography, and the results were compared with the histopathological parameters. The inter- and intra-reader reliability of multimodality ultrasound was assessed with intra-class correlation coefficients. Our results revealed that the sciatic nerve thickened at 2 wk post-crushed injury (p < 0.01), but recovered to almost normal thickness at 8 wk post-injury. Stiffness of the crushed nerve gradually increased (p < 0.01), and intraneural blood volume decreased (area under the curve, peak intensity, time to peak, p < 0.01 each) over time. Histopathological evaluation revealed obvious collagen hyperplasia and poor regenerated microvascular and sparse axonal regeneration and remyelination. Compared with that of the control group, the elastic modulus of the denervated muscle significantly increased (p < 0.05), which may be related to the increased intramuscular collagen (p < 0.01) and decreased muscle fiber cross-sectional area (p < 0.01). There were no significant differences in contrast-enhanced ultrasonography parameters (area under the curve, peak intensity, time to peak) of the denervated muscle between the crush injury groups and the control group (p >0.05). All ultrasound results had excellent inter- and intra-reader consistency (intraclass correlation coefficient >0.80). In conclusion, multimodality ultrasound techniques could provide quantitative information on the morphologic changes, mechanical properties and blood perfusion of crushed nerve and denervated muscle, which may be of great importance in clinical practice.

Risk Assessment of Injury to Palmar Cutaneous Branch of the Median Nerve Using High-Resolution Ultrasound

OBJECTIVE

To evaluate the relationship between the palmar cutaneous branch of median nerve (PCBMN) and surrounding anatomical structures by using high-resolution ultrasound (HRUS) to assess the risk of PCBMN injury.

METHODS

The PCBMN course and the characteristics of bilateral distal forearms and wrists of 30 healthy volunteers were identified. The distance between PCBMN and other anatomical structures at three different levels along its course were measured using HRUS. Moreover, the depth of PCBMN from skin and its cross-sectional area (CSA) were measured.

RESULTS

HRUS showed the PCBMN in all subjects. PCBMN branched off from the radial aspect of the median nerve (MN) at 4.69±0.89 cm proximal to the bistyloid line (BSL) and extended radially toward the flexor carpi radialis (FCR) tendon. PCBMN was within the ulnar edge of FCR tendon sheath, and became more superficial and perforated the antebrachial fascia between the FCR tendon laterally and the palmaris longus (PL) tendon medially. PCBMN was located at 4.08±0.72 mm on the ulnar aspect of the FCR tendon and 4.78±0.36 mm radially on the PL tendon at BSL. At the distal wrist crease level, the PCBMN was located at 5.68±0.58 mm on the ulnar side of the FCR tendon. The PCBMN depth from skin at BSL and its branching point was 1.92±0.41 and 7.95±0.79 mm, respectively. The PCBMN CSA was 0.26±0.15 mm2 at BSL.

CONCLUSION

HRUS can be used to identify PCBMN and its relationship with other anatomical structures. Our data can be used to predict PCBMN location, and prevent complications associated with invasive procedures involving the wrist.

Neuromuscular Ultrasound: Clinical Applications and Diagnostic Values

Advances in high-resolution ultrasound have provided clinicians with unique opportunities to study diseases of the peripheral nervous system. Ultrasound complements the clinical and electrophysiology exam by showing the degree of abnormalities in myopathies, as well as spontaneous muscle activities in motor neuron diseases and other disorders. In experienced hands, ultrasound is more sensitive than MRI in detecting peripheral nerve pathologies. It can also guide needle placement for electromyography exam, therapeutic injections, and muscle biopsy. Ultrasound enhances the ability to detect carpal tunnel syndrome and other focal nerve entrapment, as well as pathological nerve enlargements in genetic and acquired neuropathies. Furthermore, ultrasound can potentially be used as a biomarker for muscular dystrophy and spinal muscular atrophy. The combination of electromyography and ultrasound can increase the diagnostic certainty of amyotrophic lateral sclerosis, aid in the localization of brachial plexus or peripheral nerve trauma and allow for surveillance of nerve tumor progression in neurofibromatosis. Potential limitations of ultrasound include an inability to image deeper structures, with lower sensitivities in detecting neuromuscular diseases in young children and those with mitochondrial myopathies, due to subtle changes or early phase of the disease. As well, its utility in detecting critical illness neuromyopathy remains unclear. This review will focus on the clinical applications of neuromuscular ultrasound. The diagnostic values of ultrasound for screening of myopathies, neuropathies, and motor neuron diseases will be presented.

Clinical and Ultrasonographic Features of Distal Ulnar Neuropathy: A Review

Focal ulnar neuropathy at the wrist is a rare but problematic disorder often associated with the unique anatomy of this nerve as it courses through Guyon's canal, a superficial fibro-osseous tunnel in the proximal ulnar palm. The electrophysiologic features of this disorder have been well-characterized, but the sonographic anatomy of the nerve across the wrist and palm has yet to be systematically described in normal and abnormal states. In this review, we describe the basic anatomy and the sonographic appearance of the nerve in the wrist and palm in normals and individuals with pathology. The value of using US in conjunction with electrodiagnostic testing is emphasized as the two tests together provide critical information regarding etiology, predisposing factors, and functional significance. Furthermore, ultrasound is useful as a patient educational tool to promote behavioral changes that assist in nerve recovery when pathology is related to repetitive stress.

Cost-effectiveness of neuromuscular ultrasound in focal neuropathies

OBJECTIVE

To evaluate the cost-effectiveness of neuromuscular ultrasound (NMUS) for the evaluation of focal neuropathies.

METHODS

A prior prospective, randomized, double-blind controlled trial demonstrated that NMUS, when added to electrodiagnostic testing, resulted in improved clinical outcomes after 6 months of follow-up. From this study, we abstracted quality-adjusted life-years (QALYs) from the 36-item Short Form Health Survey and entered this health-utility estimate into a mixed trial and model-based cost-effectiveness analysis from the societal perspective. Costs of intervention (NMUS) were estimated from Medicare payment rates for Current Procedural Terminology codes. Health care use was otherwise estimated to be equal, but sensitivity analyses further examined this and other key assumptions. Incremental cost-effectiveness ratio (ICER) was used as the primary outcome with a willingness-to-pay threshold of $50,000 per QALY.

RESULTS

The predicted mean health outcome associated with use of NMUS was 0.079 QALY, and the mean cost was $37, resulting in an ICER of $463 per QALY. Results and conclusions remained robust across all sensitivity analyses, including variations in time horizon, initial distribution of health states, costs, and effectiveness.

CONCLUSIONS

From a societal perspective, the addition of NMUS to electrodiagnostic testing when evaluating a focal neuropathy is cost-effective. A study of longer follow-up incorporating total health care use would further quantify the value of NMUS.

CLINICALTRIALSGOV IDENTIFIER

NCT01394822.

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.

Usefulness of ultrasound assessment of median nerve mobility in carpal tunnel syndrome

BACKGROUND

Carpal tunnel syndrome (CTS) is the most common peripheral compression neuropathy of the upper extremity. Recently, dynamic ultrasound (US) imaging has shown differences in median nerve mobility between the affected and unaffected sides in CTS.

PURPOSE

The present study was performed to compare the median nerve mobility between patients with CTS and healthy individuals, and to correlate median nerve mobility with the severity of CTS.

MATERIAL AND METHODS

A total of 101 patients (128 wrists) with CTS and 43 healthy individuals (70 wrists) were evaluated. Electrodiagnostic studies were initially conducted to determine the neurophysiological grading scale (NGS). The cross-sectional area (CSA) of the median nerve and the grade of median nerve mobility were measured using US.

RESULTS

The mean grade of median nerve mobility in the CTS group (1.9) was significantly lower than that in the control group (2.6; P < 0.001). There were significant negative correlations between the grade of median nerve mobility and distal motor latency of the median nerve (r = -0.218, P = 0.015), NGS (r = -0.207, P = 0.020) and CSA of the median nerve (r = -0.196, P = 0.028).

CONCLUSION

The grade of median nerve mobility was negatively correlated with the severity of CTS. US assessment of median nerve mobility may be useful in diagnosing and determining the severity of CTS.

Quantitative Ultrasound Imaging Pixel Analysis of the Intrinsic Plantar Muscle Tissue between Hemiparesis and Contralateral Feet in Post-Stroke Patients

Quantitative ultrasound imaging of the muscle tissue may be applied in the neurology field, due to B-mode grayscale pixels values could be used as potential biomarkers for disease progression and intervention effects in poststroke patients. Thus, the study aim was to compare and analyze the ultrasound imaging B-mode pixels differences between the intrinsic plantar muscles cross-sectional area (CSA) in hemiparetic and contralateral feet from poststroke patients by means of the Image J software. A case-control design and a convenience sampling method were used in order to recruit 22 feet from 11 poststroke patients. This total sample was divided into 11 hemiparetic feet and 11 contralateral feet. The Image J software was used in order to evaluate the interface distance, CSA as well as measure the pixels mean, standard deviation (SD) and count from all offline images in the flexor digitorum brevis, abductor hallucis (AbH), and flexor hallucis brevis muscles. Statistically significant differences (p = 0.003) were only shown for the pixels count in the AbH muscle. The rest of outcome measurements did not show any statistically significant difference (p > 0.05). Therefore, B-mode ultrasound imaging Image J software differences for the pixels count reduction were shown in the AbH muscle between hemiparetic and contralateral feet from poststroke patients. Further studies are necessary in order to apply our findings as potential biomarkers during the stroke disease course.

Basis of Shoulder Nerve Entrapment Syndrome: An Ultrasonographic Study Exploring Factors Influencing Cross-Sectional Area of the Suprascapular Nerve

As changes in nerves' shape and size are common ultrasonographic findings of entrapment neuropathy, measurement of the nerve cross-sectional area (CSA) becomes the mostly used indicator to differentiate normality from pathology. Recently, more US research has been conducted to measure the shape of the suprascapular notch and the diameter of the suprascapular nerve. Because the suprascapular nerve is paramount for various shoulder disorders, the present study aims to establish normal values of suprascapular nerve sizes at different levels as well as to investigate potential influence of participants' characteristics on the CSA measurements. The present study used a cross-sectional design investigating the CSA values of the suprascapular nerve from the supraclavicular region to spinoglenoid notch. We employed the inside-epineurium and outside-epineurium methods to quantify CSA of cervical roots (C5 and C6) and the suprascapular nerve on US imaging. Univariate comparisons of nerve sizes among different age and gender groups were carried out. Multivariate analysis was performed to analyze the impact of participants' characteristics on nerve CSA. Repeated measurement analysis of variance was conducted to examine segmental variations of CSA of the suprascapular nerve from its origin to infraspinatus fossa. Our study included 60 healthy adults with 120 shoulders and had three major findings: (1) the inside-epineurium method was more reliable than the outside-epineurium approach for CSA measurements due to higher intra- and inter-rater reliability, (2) women had smaller sizes for cervical nerve roots and for the most proximal segment of the suprascapular nerves, and (3) using the outside-epineurium method, the suprascapular nerve CSA was larger in its distal division than the portion proximal to the mid-clavicular line. In conclusion, the inside-epineurium method has better reliability for nerve CSA assessment but the outside-epineurium method is needed for quantifying the size of distal suprascapular nerve. Gender difference in CSA values should be considered during evaluation of the most proximal nerve segment. Using the outside-epineurium method, the distal suprascapular nerve would be estimated larger than its proximal portion and the segmental discrepancy should be not misinterpreted as pathology.

Indications for neuromuscular ultrasound: Expert opinion and review of the literature

Over the last two decades, dozens of applications have emerged for ultrasonography in neuromuscular disorders. We wanted to measure its impact on practice in laboratories where the technique is in frequent use. After identifying experts in neuromuscular ultrasound and electrodiagnosis, we assessed their use of ultrasonography for different indications and their expectations for its future evolution. We then identified the earliest papers to provide convincing evidence of the utility of ultrasound for particular indications and analyzed the relationship of their date of publication with expert usage. We found that experts use ultrasonography often for inflammatory, hereditary, traumatic, compressive and neoplastic neuropathies, and somewhat less often for neuronopathies and myopathies. Usage significantly correlated with the timing of key publications in the field. We review these findings and the extensive evidence supporting the value of neuromuscular ultrasound. Advancement of the field of clinical neurophysiology depends on widespread translation of these findings.

Neuromuscular ultrasound in electrically non-localizable ulnar neuropathy

INTRODUCTION

The aim of this study was to determine the value of high-resolution ultrasound (HRUS) in patients with ulnar neuropathy whose electrophysiology displayed an axonal, non-localizing pattern.

METHODS

A prospective study of patients referred to an electromyography laboratory for ulnar neuropathy was performed. Of the 56 patients with clinical and electrodiagnostic (EDx) evidence of ulnar neuropathy, 12 were identified with non-localizing electrophysiology who subsequently underwent HRUS of the ulnar nerve.

RESULTS

HRUS localized the ulnar neuropathy in all patients. In 2 patients, HRUS demonstrated structural lesions not at the elbow.

DISCUSSION

HRUS often adds complementary information to standard EDx studies, including ulnar neuropathy. Thus, HRUS should be employed in patients with a non-localizing ulnar neuropathy on EDx studies. Muscle Nerve 58: 655-659, 2018.

Prevalence of carpal tunnel syndrome presenting with symptoms in an ulnar nerve distribution: A prospective study

INTRODUCTION

Patients presenting with symptoms of pain/paresthesias primarily in an ulnar nerve distribution may be noted to have exclusive median mononeuropathy at the wrist on subsequent electrodiagnostic testing. There has been limited research looking at the prevalence of this clinical presentation.

METHODS

A cohort of adults were surveyed to assess for severity and localization of hand symptoms using the Katz hand diagram and Boston Carpal Tunnel Questionnaire Symptoms Severity Scale. Thirty volunteers met our case definition for ulnar neuropathy and underwent a standardized physical examination, electrodiagnostic testing, and nerve ultrasound.

RESULTS

Eleven of 30 subjects (37%) were found to have exclusive median mononeuropathy at the wrist.

DISCUSSION

Carpal tunnel syndrome should remain high on the differential for patients presenting with symptoms of pain/paresthesias primarily in an ulnar nerve distribution. Muscle Nerve 59:60-63, 2019.

Ultrasonographic reference values for the deep branch of the radial nerve at the arcade of Frohse

PURPOSE

The deep branch of the radial nerve (DBRN) enters the forearm as it passes under the arcade of Frohse. This is the most common entrapment site of the DBRN in the forearm. In this study, we investigated the ultrasonographic reference values for the diameters and cross-sectional area (CSA) of the DBRN at the level of the arcade of Frohse in a healthy sample of the population.

METHODS

Sixty-five healthy Caucasian volunteers (130 nerves) were recruited for this study. The reference range [mean ± 2 standard deviations (SD); 2.5th-97.5th quintiles] and the upper limit of the side-to-side difference were determined. The effects of age, gender, handedness, height, and body mass index were examined.

RESULTS

The mean age was 41.8 ± 11.2 years (range 18-75 years). The mean ± 2SD of the CSA was 0.50-1.42 mm². The upper limit of the normal side-to-side difference was 0.35 mm². The differences between males and females and between the dominant and non-dominant arms were not significant. The mean anteroposterior and transverse diameters were 0.83 ± 0.13 and 1.23 ± 0.29 mm, respectively. A significant correlation between the dominant-side CSA and age (r = 0.41; p < 0.001) was observed. The correlations between CSA and height (r = 0.19; p = 0.12) and body mass index (r = 0.22; p = 0.07) were not significant.

CONCLUSION

The measurements obtained in this study are valuable for examining DBRN pathologies using high-frequency ultrasound. The findings showed that age was associated with the DBRN CSA, while gender, height, and body mass index were not.

Ulnar neuropathy at wrist: entrapment at a very "congested" site

Ulnar tunnel syndrome indicates ulnar neuropathy at different sites within the wrist. Several classifications of ulnar tunnel syndrome are present in literature, based upon typical nerve anatomy. However, anatomical variations are not uncommon and can complicate assessment. The etiology is also complex, due to the numerous potential causes of entrapment. Clinical examination, neurophysiological testing, and imaging are all used to support the diagnosis. At present, many therapeutic approaches are available, ranging from observation to surgical management. Although ulnar neuropathy at the wrist has undergone extensive prior study, unresolved questions on diagnosis and treatment remain. In the current paper, we review relevant literature and present the current knowledge on ulnar tunnel syndrome.

Ultrasonographic reference values for the median nerve at the level of pronator teres muscle

PURPOSE

The purpose of this study was to investigate the ultrasonographic reference values for diameters and cross-sectional area (CSA) of the median nerve between the two heads of the pronator teres muscle in healthy population as well as to correlate the findings with height, weight, sex and age.

METHODS

Fifty-five healthy Caucasian volunteers (110 median nerves) were included in this study. The reference range (mean ± 2 standard deviations; 2.5th-97.5th quintiles) and the upper limit of side-to-side difference of the median nerve between the two heads of the pronator teres muscle were investigated using high-frequency ultrasound. The effects of age, sex, height, handedness, and body mass index (BMI) were examined.

RESULTS

The mean age was 39.4 ± 10.6 years (range 18-75 years). The mean ± 2SD of the median CSA was 4.9-12.9 mm². The upper limit of normal side-to-side difference was 3.0 mm². The differences between genders and between the dominant and non-dominant hands were not significant. The mean antero-posterior and transverse diameters were 7.2 ± 1.5 and 10.7 ± 2.4 mm, respectively. Significant correlations were observed between the dominant-side CSA and BMI (r = 0.33; p = 0.01) and age (r = 0.31; p = 0.02). The correlation between the CSA and height (r = 0.19; p = 0.16) was not significant.

CONCLUSIONS

The measurements obtained in this study are of importance for examining median nerve entrapments in the forearm using high-frequency ultrasound. Age and BMI showed to be correlated with median nerve CSA; while gender and height were not.

[Diagnostic nerve ultrasonography]

CLINICAL/METHODICAL ISSUE

For the diagnostics of nerve lesions an imaging method is necessary to visualize peripheral nerves and their surrounding structures for an etiological classification.

STANDARD RADIOLOGICAL METHODS

Clinical neurological and electrophysiological investigations provide functional information about nerve lesions. The information provided by a standard magnetic resonance imaging (MRI) examination is inadequate for peripheral nerve diagnostics; however, MRI neurography is suitable but on the other hand a resource and time-consuming method.

METHODICAL INNOVATIONS

Using ultrasonography for peripheral nerve diagnostics.

PERFORMANCE

With ultrasonography reliable diagnostics of entrapment neuropathies and traumatic nerve lesions are possible. The use of ultrasonography for neuropathies shows that a differentiation between different forms is possible.

ACHIEVEMENTS

Nerve ultrasonography is an established diagnostic tool. In addition to the clinical examination and clinical electrophysiology, structural information can be obtained, which results in a clear improvement in the diagnostics. Ultrasonography has become an integral part of the diagnostic work-up of peripheral nerve lesions in neurophysiological departments.

PRACTICAL RECOMMENDATIONS

Nerve ultrasonography is recommended for the diagnostic work-up of peripheral nerve lesions in addition to clinical and electrophysiological investigations. It should be used in the clinical work-up of entrapment neuropathies, traumatic nerve lesions and spacy-occupying lesions of nerves.