Cross-sectional area reference values for nerve ultrasonography

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.

Investigation of the Diagnostic Value of Ultrasonography for Radial Neuropathy Located at the Spiral Groove

Objective

To determine a diagnostic cut-off value for the cross-sectional area (CSA) of the radial nerve using ultrasonography for radial neuropathy located at the spiral groove (SG).

Methods

Seventeen patients with electrodiagnostic evidence of radial neuropathy at the SG and 30 healthy controls underwent ultrasonography of the radial nerve at the SG . The CSAs at the SG were compared in the patient and control groups. The CSA at the SG between the symptomatic and asymptomatic sides (ΔSx–Asx and Sx/Asx, respectively) were analyzed to obtain the optimal cut-off value. The relationship between the electrophysiological severity of radial neuropathy and CSA was also evaluated.

Results

Among the variables examined, there were statistically significant differences in the CSA between the patient and control groups, ΔSx–Asx, and Sx/Asx at the SG. In a receiver operating characteristics analysis, the cut-off CSA was 5.75 mm² at the SG (sensitivity 52.9%, specificity 90%), 1.75 mm² for ΔSx–Asx (sensitivity 58.8%, specificity 100%), and 1.22 mm² for Sx/Asx (sensitivity 70.6%, specificity 93.3%) in diagnosing radial neuropathy at the SG. There was no significant correlation between CSA and electrophysiological severity score for either patient group.

Conclusion

The reference value obtained for CSA of the radial nerve at the SG may facilitate investigation of radial nerve pathologies at the SG.

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.

Common Entrapment Neuropathies

PURPOSE OF REVIEW

This article addresses relevant peripheral neuroanatomy, clinical presentations, and diagnostic findings in common entrapment neuropathies involving the median, ulnar, radial, and fibular (peroneal) nerves.

RECENT FINDINGS

Entrapment neuropathies are a common issue in general neurology practice. Early diagnosis and effective management of entrapment mononeuropathies are essential in preserving limb function and maintaining patient quality of life. Median neuropathy at the wrist (carpal tunnel syndrome), ulnar neuropathy at the elbow, radial neuropathy at the spiral groove, and fibular neuropathy at the fibular head are among the most frequently encountered entrapment mononeuropathies. Electrodiagnostic studies and peripheral nerve ultrasound are employed to help confirm the clinical diagnosis of nerve compression or entrapment and to provide precise localization for nerve injury. Peripheral nerve ultrasound demonstrates nerve enlargement at or near sites of compression.

SUMMARY

Entrapment neuropathies are commonly encountered in clinical practice. Accurate diagnosis and effective management require knowledge of peripheral neuroanatomy and recognition of key clinical symptoms and findings. Clinical diagnoses may be confirmed by diagnostic testing with electrodiagnostic studies and peripheral nerve ultrasound.

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.

Estimation of ultrasound reference values for the lower limb peripheral nerves in adults: A cross-sectional study

The objective of this study is to estimate the reference values for the lower limb peripheral nerves in adults.The demographics and physical characteristics of 69 adult healthy volunteers were evaluated and recorded. The estimated reference values and their correlations with the age, weight, height, body mass index (BMI) were evaluated.The cross sectional area reference values were obtained at 5 predetermined sites for 3 important lower limb peripheral nerves. Our CSA values correlated significantly with age, weight, and BMI. The normal reference values for each nerve were as follows: Tibial nerve at the popliteal fossa 19 mm ± 6.9, tibial nerve at the level of the medial malleolus 12.7 mm ± 4.5, common peroneal nerve at the popliteal fossa 9.5 mm ± 4, common peroneal nerve fibular head 8.9 mm ± 3.2, sural nerve 3.5 mm ± 1.4.The reference values for the lower limb peripheral nerves were identified. These values could be used for future management of peripheral nerve disorders.

Nerve ultrasound in polyneuropathies

Ultrasound can be used to visualize pathology in the peripheral nerves of patients with polyneuropathy. Nerve enlargement is the most frequent pathology, but other abnormalities, including abnormal nerve echogenicity and vascularity, are also encountered. This monograph presents an overview of the role of nerve ultrasound in the evaluation and management of both inherited and acquired polyneuropathies. A description of the sonographic techniques and common abnormalities is provided, followed by a presentation of typical findings in different neuropathies. Scoring systems for characterizing the presence and pattern of nerve abnormalities as they relate to different polyneuropathies are presented. Muscle Nerve 57: 716-728, 2018.

High resolution ultrasonography of the tibial nerve in diabetic peripheral neuropathy

Aim of the study

High-resolution ultrasonography of the tibial nerve is a fast and non invasive tool for diagnosis of diabetic peripheral neuropathy. Our study was aimed at finding out the correlation of the cross sectional area and maximum thickness of nerve fascicles of the tibial nerve with the presence and severity of diabetic peripheral neuropathy.

Material and methods

75 patients with type 2 diabetes mellitus clinically diagnosed with diabetic peripheral neuropathy were analysed, and the severity of neuropathy was determined using the Toronto Clinical Neuropathy Score. 58 diabetic patients with no clinical suspicion of diabetic peripheral neuropathy and 75 healthy non-diabetic subjects were taken as controls. The cross sectional area and maximum thickness of nerve fascicles of the tibial nerves were calculated 3 cm cranial to the medial malleolus in both lower limbs.

Results

The mean cross sectional area (22.63 +/- 2.66 mm²) and maximum thickness of nerve fascicles (0.70 mm) of the tibial nerves in patients with diabetic peripheral neuropathy compared with both control groups was significantly larger, and statistically significant correlation was found with the Toronto Clinical Neuropathy Score (p < 0.001). The diabetic patients with no signs of peripheral neuropathy had a larger mean cross sectional area (14.40 +/- 1.72 mm²) and maximum thickness of nerve fascicles of the tibial nerve (0.40 mm) than healthy non-diabetic subjects (12.42 +/- 1.01 mm² and 0.30 mm respectively).

Conclusion

The cross sectional area and maximum thickness of nerve fascicles of the tibial nerve is larger in diabetic patients with or without peripheral neuropathy than in healthy control subjects, and ultrasonography can be used as a good screening tool in these patients.

Peripheral nerve diffusion tensor imaging (DTI): normal values and demographic determinants in a cohort of 60 healthy individuals

OBJECTIVE

To identify demographic determinants of peripheral nerve diffusion tensor imaging (DTI) and to establish normal values for fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (MD).

METHODS

Sixty subjects were examined at 3 Tesla by single-shot DTI. FA, AD, RD, and MD were collected for the sciatic, tibial, median, ulnar, and radial nerve and were correlated with demographic variables.

RESULTS

Mean FA of all nerves declined with increasing age (r = -0.77), which could be explained by RD increasing (r = 0.56) and AD declining (r = -0.40) with age. Moreover, FA was inversely associated with height (r = -0.28), weight (r = -0.38) and BMI (r = -0.35). Although FA tended to be lower in men than women (p = 0.052), this difference became completely negligible after adjustment to body weight. A multiple linear regression model for FA was calculated with age and weight as predictors (defined by backward variable selection), yielding an R ² = 0.71 and providing a correction formula to adjust FA for age and weight.

CONCLUSION

Peripheral nerve DTI parameters depend on demographic variables. The most important determinants age and weight should be considered in all studies employing peripheral nerve DTI.

KEY POINTS

• Peripheral nerve diffusion tensor imaging (DTI) parameters depend on demographic variables. • Fractional anisotropy (FA) declines with increasing age and weight. • Gender does not systematically affect peripheral nerve DTI. • The formula presented here allows adjustment of FA for demographic variables.

Reliability of measurement of the carpal tunnel and median nerve in asymptomatic subjects with ultrasound

BACKGROUND

Morphology of the carpal tunnel changes with varying wrist postures and compressive forces applied to the wrist. These changes may affect the morphology and pressure on the median nerve and could be used as part of the treatment of the carpal tunnel syndrome patients. Reliability of the ultrasonographic measurements of the median nerve has been widely studied. However, there is a lack of investigation regarding reliability of ultrasonographic measurements of the carpal tunnel.

OBJECTIVE

The purpose of this study was to assess intra-tester and inter-tester reliability of measurement of dimensions of the carpal tunnel and median nerve with ultrasound in asymptomatic volunteers.

DESIGN

A cross-sectional methodological study.

METHODS

Aspects measured were mediolateral and anteroposterior diameters, flattening ratio, circularity, perimeter and cross-section area of the carpal tunnel and median nerve.

RESULTS

Intra-tester reliability was excellent for the carpal tunnel (ICCs from 0.91 to 0.97) and for the median nerve (ICCs from 0.79 to 0.94) measurements. The flattening ratio of the median nerve showed good agreement (ICC = 0.68). Inter-tester reliability was excellent for the carpal tunnel measurements (ICCs from 0.76 to 0.95) and, for the cross sectional area, the perimeter and mediolateral diameter of the median nerve, the ICC values were 0.89, 0.84 and 0.81, respectively.

CONCLUSION

In the context of this study, ultrasound was a reliable instrument for measuring carpal tunnel and median nerve dimensions in asymptomatic subjects.

LEVEL OF EVIDENCE

1b.

Estimation of ultrasound reference values for the upper limb peripheral nerves in adults: A cross-sectional study

The objective of this study is to estimate the reference values for the upper limb peripheral nerves in adults.The demographics and physical characteristics of 69 adult healthy volunteers were evaluated and recorded. In addition, the side to side differences of the estimated reference values and their correlations with the age, weight, height, and body mass index (BMI) were evaluated.Cross-sectional area reference values of the upper limb nerves did not correlate with height; however, they correlated with age, weight, and BMI in some scanned sites.The data obtained in this study could be helpful in future diagnosis of peripheral nerve disorders of the upper limb.

The spectrum of Charcot-Marie-Tooth disease due to myelin protein zero: An electrodiagnostic, nerve ultrasound and histological study

OBJECTIVE

Nerve ultrasound (US) data on myelin protein zero (MPZ)-related Charcot-Marie-Tooth disease (CMT) are lacking. To offer a comprehensive perspective on MPZ-related CMTs, we combined nerve US with clinics, electrodiagnosis and histopathology.

METHODS

We recruited 36 patients (12 MPZ mutations), and correlated nerve US to clinical, electrodiagnostic measures, and sural nerve biopsy.

RESULTS

According to motor nerve conduction velocity (MNCV) criteria, nine patients were categorized as "demyelinating" CMT1B, 17 as "axonal" CMT2I/J, and 10 as dominant "intermediate" CMTDID. Sural nerve biopsy showed hypertrophic de-remyelinating neuropathy with numerous complex onion bulbs in one patient, de-remyelinating neuropathy with scanty/absent onion bulbs in three, axonal neuropathy in two, mixed demyelinating-axonal neuropathy in five. Electrodiagnosis significantly differed in CMT1B vs. CMT2I/J and CMTDID subgroups. CMT1B had slightly enlarged nerve cross sectional area (CSA) especially at proximal upper-limb (UL) sites. CSA was negatively correlated to UL MNCV and not increased at entrapment sites. Major sural nerve pathological patterns were uncorrelated to UL nerve US and MNCV.

CONCLUSIONS

Sural nerve biopsy confirmed the wide pathological spectrum of MPZ-CMT. UL nerve US identified two major patterns corresponding to the CMT1B and CMT2I/J-CMTDID subgroups.

SIGNIFICANCE

Nerve US phenotype of MPZ-CMT diverged from those in other demyelinating peripheral neuropathies and may have diagnostic value.

Ultrasonography in Peripheral Nervous System Diagnosis

PURPOSE OF REVIEW

High-resolution ultrasound has made it possible to view most nerves and muscles in real time and to identify pathologic change in size, echo texture, and vascularity. This article focuses on the principles underlying ultrasound imaging and the application of ultrasound imaging to clinical disorders commonly seen in an electrodiagnostic laboratory.

RECENT FINDINGS

Ultrasound is a sensitive and specific tool for evaluating myopathic and neurogenic muscle disease. It provides useful information about muscles difficult to study with other technologies, such as the tongue and diaphragm, and is also helpful in evaluating smaller muscles in the hands or feet where correlation with electrodiagnostic studies is possible. For nerves, the resolution of ultrasound is such that it can sensitively identify focal nerve enlargement, which is accurate in the diagnosis of entrapment neuropathies. Furthermore, it can recognize diffuse or multifocal nerve enlargement seen in hereditary and inflammatory neuropathies.

SUMMARY

Neuromuscular ultrasound is an informative noninvasive tool for evaluating nerve and muscle disease. As the technology continues to advance and becomes widely available, it may become a routine part of residency training, neuromuscular research, and clinical practice.

Comparing Electrical Stimulation With and Without Ultrasound Guidance for Phenol Neurolysis to the Musculocutaneous Nerve

BACKGROUND

Ultrasound guidance is increasingly being used for neurolytic procedures that have traditionally been done with electrical stimulation (e-stim) guidance alone. Ultrasound visualization with e-stim-guided neurolysis can potentially allow adjustments in injection protocols that will reduce the volume of neurolytic agent needed to achieve clinical improvement.

OBJECTIVE

This study compared e-stim only to e-stim with ultrasound guidance in phenol neurolysis of the musculocutaneous nerve (MCN) for elbow flexor spasticity. We also evaluated the ultrasound appearance of the MCN in this population.

DESIGN

Retrospective review.

SETTING

University hospital outpatient clinic.

PARTICIPANTS

Adults (N = 167) receiving phenol neurolysis to the MCN for treatment of elbow flexor spasticity between 1997 and 2014 and adult control subjects.

METHODS

For each phenol injection of the MCN, the method of guidance, volume of phenol injected, technical success, improved range of motion at the elbow postinjection, adverse effects, reason for termination of injections, and details of concomitant botulinum toxin injection were recorded. The ultrasound appearance of the MCN, including nerve cross-sectional area and shape, were recorded and compared between groups.

MAIN OUTCOME MEASURES

The volume of phenol injected and MCN cross-sectional area and shape as demonstrated by ultrasound.

RESULTS

The addition of ultrasound to e-stim-guided phenol neurolysis was associated with lower doses of phenol when compared to e-stim guidance alone (2.31 mL versus 3.69 mL, P < .001). With subsequent injections, the dose of phenol increased with e-stim guidance (P < .001), but not with e-stim and ultrasound guidance (P = .95). Both methods of guidance had high technical success, improved ROM at elbow postinjection, and low rates of adverse events. In comparing the ultrasound appearance of the MCN in patients with spasticity to that of normal controls, there was no difference in the cross-sectional area of the nerve, but there was more variability in shape.

CONCLUSIONS

Combined e-stim and ultrasound guidance during phenol neurolysis to the MCN allows a smaller volume of phenol to be used for equal effect, both at initial and repeat injection. The MCN shape was more variable in individuals with spasticity; this should be recognized so as to successfully locate the nerve to perform neurolysis.

LEVEL OF EVIDENCE

IV.

Ultrasound assessment of the sural nerve in patients with neuropathic pain after ankle surgery

INTRODUCTION

The sural nerve may be damaged after ankle injury. The aim of our study was to determine the diagnostic utility of high-resolution sonography in patients with ankle fractures treated by open reduction and internal fixation in whom there was a clinical suspicion of sural neuropathy.

METHODS

We examined the ultrasound (US) characteristics of patients with and without postsurgical sural neuropathic pain and healthy volunteers. Cross-sectional area (CSA), echogenicity, and vascularization of the sural nerves were recorded.

RESULTS

Fourteen participants and all sural nerves were identified. CSA (P < 0.001) and vascularization (P = 0.002) were increased in symptomatic patients when compared with asymptomatic patients and healthy volunteers. There were no significant differences in nerve echogenicity (P = 0.983).

DISCUSSION

US may be a valuable tool for evaluating clinically suspected sural nerve damage after ankle stabilization surgery. Sural nerve abnormalities are seen in patients with postsurgical neuropathic pain. Muscle Nerve 57: 407-413, 2018.

High-resistance strength training does not affect nerve cross sectional area - An ultrasound study

•

Trained individuals did not have larger cross-sectional area of peripheral nerves than untrained individuals.

•

Trained individuals had thicker biceps muscles.

•

Nerve CSA of the median nerve in the forearm correlated with participants’ height, and was larger in men than women.

Objective

The aim was to study the effect of high-resistance strength training on peripheral nerve morphology, by examining properties of peripheral nerves as well as distal and proximal muscle thickness with ultrasound, comparing healthy individuals who perform and do not perform high-resistance strength training.

Methods

Neuromuscular ultrasound was used to examine cross sectional area (CSA) of the median and musculocutaneous nerves, and muscle thickness of the abductor pollicis brevis muscle, biceps brachii muscle, quadriceps muscle and extensor digitorum brevis muscle, in 44 healthy individuals, of whom 22 performed regular high-resistance strength training.

Results

No difference in nerve CSA was found between trained and untrained individuals although trained individuals had thicker biceps brachii muscles. The CSA of the median nerve in the forearm correlated with participants’ height and was significantly larger in men than women.

Conclusions

In this cohort, CSA of the median and musculocutaneous nerves was not affected by strength training, whereas gender had a prominent effect both on CSA and muscle thickness.

Significance

This is the first study to examine the effect of high-resistance strength training on peripheral nerves with neuromuscular ultrasound.

Peripheral nerve ultrasonography in patients with transthyretin amyloidosis

OBJECTIVE

To systematically study peripheral nerve morphology in patients with transthyretin (TTR) amyloidosis and TTR gene mutation carriers using high-resolution ultrasonography (US).

METHODS

In this prospective cross-sectional study we took a structured history, performed neurological examination, and measured peripheral nerve cross-sectional areas (CSAs) bilaterally at 28 standard locations using US. Demographic and US findings were compared to controls.

RESULTS

Peripheral nerve CSAs were significantly larger in 33 patients with familial amyloid polyneuropathy (FAP) compared to 50 controls, most dramatically at the common entrapment sites (median nerve at the wrist, ulnar nerve at the elbow), and in the proximal nerve segments (median nerve in the upper arm, sciatic nerve in the thigh). Findings in 21 asymptomatic TTR gene mutation carriers were less marked compared to controls, with CSAs being larger only in the median nerve in the upper arm. Nerve CSAs correlated with abnormalities on nerve conduction studies.

CONCLUSION

Using US, we confirmed previous pathohistological and imaging reports in FAP of the most pronounced peripheral nerve thickening in the proximal limb segments.

SIGNIFICANCE

Similar to US findings in diabetic and vasculitic neuropathies these predominantly proximal locations of nerve thickening may be attributed to ischaemic nerve damage caused by poor perfusion in the watershed zones along proximal limb segments.

Diagnostic Cutoff Value for Ultrasonography of the Common Fibular Neuropathy at the Fibular Head

Objective

To establish the diagnostic cutoff value of ultrasonographic measurement for common fibular neuropathy (CFN) at the fibular head (FH).

Methods

Twenty patients with electrodiagnostically diagnosed CFN at the FH and 30 healthy controls were included in the study. The cross-sectional area (CSA) of sciatic nerve at mid-thigh level, common fibular nerve at popliteal fossa (PF), and common fibular (CF) nerve at FH were measured. Additionally, the difference of CF nerve CSA at the FH between symptomatic side and asymptomatic side (ΔSx–Asx), the ratio of CF nerve CSA at FH to at PF (FH/PF), and the ratio of CF nerve CSA at the FH symptomatic side to asymptomatic side (Ratio Sx–Asx) were calculated.

Results

CSA at the FH, FH/PF, ΔSx–Asx, and Ratio Sx–Asx showed significant differences between the patient and control groups. The cutoff value for diagnosing CFN at the FH was 11.7 mm² for the CSA at the FH (sensitivity 85.0%, specificity 90.0%), 1.70 mm² for the ΔSx–Asx (sensitivity 83.3%, specificity 97.0%), 1.11 for the FH/PF (sensitivity 47.1%, specificity 93.3%), and 1.24 for the Ratio Sx–Asx (sensitivity 72.2%, specificity 96.7%).

Conclusion

The ultrasonographic measurement and cutoff value could be a valuable reference in diagnosing CFN at the FH and improving diagnostic reliability and efficacy.

Diabetic peripheral neuropathy: Correlation between nerve cross-sectional area on ultrasound and clinical features

BACKGROUND AND OBJECTIVE

To evaluate the correlations of the cross-sectional area (CSA) of peripheral nerves in diabetic peripheral neuropathy (DPN) patients based on ultrasound (US) with clinical and demographic characteristics.

METHODS

A DPN patient group (n= 53) and a matched healthy control group (n= 53) underwent US imaging of the sciatic, tibial and median nerves. The CSAs of these nerves were recorded, and their associations with pain intensity according to the visual analog scale (VAS) score and the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) pain scale score, diabetes mellitus (DM) duration, body mass index (BMI), HbA1c level and blood glucose levels were evaluated.

RESULTS

The CSAs of the examined nerves in diabetic patients were larger than those in healthy individuals (p< 0.05). No correlations were detected between the CSAs of the examined nerves and the parameters of interest (p> 0.05), including the VAS and LANSS pain scale scores (p= 0.32 and p= 0.31, respectively).

CONCLUSIONS

US is a sensitive diagnostic technique for detecting DPN; however, it does not indicate disease severity.

Ultrasonography of Leprosy Neuropathy: A Longitudinal Prospective Study

BACKGROUND

Previous studies have shown that leprosy multi-drug therapy (MDT) does not stop the progression of nerve function impairment. There are no prospective studies investigating the evolution of nerve anatomic abnormalities after treatment. We examined leprosy patients aiming to investigate the evolution of nerve ultrasonography (US) abnormalities and the risk factors for poor outcomes after MDT.

METHODOLOGY/PRINCIPAL FINDINGS

We performed bilateral US of the ulnar (U), median (M) and common fibular (CF) nerves in 9 paucibacillary (PB) and 64 multibacillary (MB) patients before and after MDT. Forty-two patients had leprosy reactions (type 1, type 2, acute neuritis) during the study. We analyzed nerve maximum cross-sectional areas (CSA), echogenicity and Doppler signal. Poor outcomes included a post-treatment CSA above normal limits with a reduction of less than 30% (U, M) or 40% (CF) from the baseline, echogenicity abnormalities or intraneural Doppler in the post-treatment study. We found that PB and patients without reactions showed significant increases in CSA at CF, whereas MB and patients with reactions had CSA reduction in some nerves after treatment (p<0.05). Despite this reduction, we observed a greater frequency of poor CSA outcomes in the MB compared to the PB (77.8% and 40.6%; p>0.05) and in the patients with reactions compared to those without (66.7% and 38.7%; p<0.05). There was significantly higher odds ratio (7.75; 95%CI: 1.56-38.45) for poor CSA outcomes only for M nerve in patients with reactions. Poor echogenicity outcomes were more frequent in MB (59.4%) compared to PB (22.2%) (p<0.05). There was significant association between poor Doppler outcomes and neuritis. Gender, disease duration, and leprosy classification were not significant risk factors for poor outcomes in CSA, echogenicity or Doppler.

CONCLUSIONS/SIGNIFICANCE

US nerve abnormalities can worsen after treatment despite the leprosy classification or the presence of reactions.

Nerve ultrasound in clinical management of carpal tunnel syndrome in mucopolysaccharidosis

AIM

Mucopolysaccharidoses (MPS) are a group of diseases with an almost 100% lifetime incidence of carpal tunnel syndrome (CTS) in MPSsubtypes I, II, and VI. We compared nerve ultrasound with clinical signs and electrophysiology in a clinical setting to screen for CTSin MPS.

METHOD

Twenty-four patients (13 male, 11 female, mean age of 7y 11mo [SD8y 5mo], range 6mo-29y) were screened for CTS. Eight of these patients were re-examined post-operatively. Clinical signs, distal motor latency, compound muscle action potential, sensory nerve action potential amplitude and velocity, as well as echogenicity and the cross-sectional area (CSA) of the median nerve at the wrist and forearm determined with ultrasound were assessed and the wrist to forearm ratio (WFR) calculated. Eighteen healthy participants formed a comparison group, who were also investigated with nerve ultrasound.

RESULTS

In 26% of the patients' hands, clinical signs of CTSwere present; 77% fulfilled electrophysiological and 92% nerve ultrasound criteria for CTS. Post-operatively, electrophysiology improved significantly, whereas ultrasound results were unchanged. In the comparison group, age and height correlated with the CSA, but not with WFR.

INTERPRETATION

Nerve ultrasound is a useful and painless primary screening tool for CTSin MPS.

Evaluation of the Tibial Nerve with Shear-Wave Elastography: A Potential Sonographic Method for the Diagnosis of Diabetic Peripheral Neuropathy

Purpose To evaluate the value of shear-wave elastography (SWE) in the detection of diabetic peripheral neuropathy (DPN) of the tibial nerve. Materials and Methods This study was approved by the institutional review board, and written informed consent was obtained from all study participants. The study included 20 diabetic patients with DPN (10 men, 10 women), 20 diabetic patients without DPN (eight men, 12 women), and 20 healthy control subjects (nine men, 11 women). The tibial nerve was examined at 4 cm proximal to the medial malleolus with gray-scale ultrasonography and SWE. The nerve cross-sectional area (in square centimeters) and the mean nerve stiffness (in kilopascals) within the range of the image were recorded. Inter- and intrareader variability, differences among groups, and correlation of clinical and electrophysiologic evaluation were assessed with intraclass correlation coefficients, the Mann Whitney U test, and the Wilcoxon signed rank test. Results Between diabetic patients with and diabetic patients without DPN, mean age (60 years [range, 38-79 years] vs 61 years [range, 46-75 years], respectively), mean duration of diabetes (10 years [range, 1-25 years] vs 10 years [range, 2-26 years]), and mean body mass index (31.4 kg/m² [range, 24.7-48.1 kg/m²] vs 29.8 kg/m² [range, 22.9-44.0 kg/m²]) were not significantly different. Diabetic patients without DPN had significantly higher stiffness values on the right side compared with control subjects (P < .001). Patients with DPN had much higher stiffness values on both sides compared with both diabetic patients without DPN (P < .001) and healthy control subjects (P < .001). A cutoff value of 51.0 kPa at 4 cm proximal to the medial malleolus revealed a sensitivity of 90% (95% confidence interval [CI]: 75.4%, 96.7%) and a specificity of 85.0% (95% CI: 74.9%, 91.7%). Conclusion Tibial nerve stiffness measurements appear to be highly specific in the diagnosis of established DPN. The increased stiffness in subjects without DPN might indicate that the nerve is affected by diabetes. ^© RSNA, 2016 Online supplemental material is available for this article.

Development of Kinematic Graphs of Median Nerve during Active Finger Motion: Implications of Smartphone Use

Background

Certain hand activities cause deformation and displacement of the median nerve at the carpal tunnel due to the gliding motion of tendons surrounding it. As smartphone usage escalates, this raises the public’s concern whether hand activities while using smartphones can lead to median nerve problems.

Objective

The aims of this study were to 1) develop kinematic graphs and 2) investigate the associated deformation and rotational information of median nerve in the carpal tunnel during hand activities.

Methods

Dominant wrists of 30 young adults were examined with ultrasonography by placing a transducer transversely on their wrist crease. Ultrasound video clips were recorded when the subject performing 1) thumb opposition with the wrist in neutral position, 2) thumb opposition with the wrist in ulnar deviation and 3) pinch grip with the wrist in neutral position. Six still images that were separated by 0.2-second intervals were then captured from the ultrasound video for the determination of 1) cross-sectional area (CSA), 2) flattening ratio (FR), 3) rotational displacement (RD) and 4) translational displacement (TD) of median nerve in the carpal tunnel, and these collected information of deformation, rotational and displacement of median nerve were compared between 1) two successive time points during a single hand activity and 2) different hand motions at the same time point. Finally, kinematic graphs were constructed to demonstrate the mobility of median nerve during different hand activities.

Results

Performing different hand activities during this study led to a gradual reduction in CSA of the median nerve, with thumb opposition together with the wrist in ulnar deviation causing the greatest extent of deformation of the median nerve. Thumb opposition with the wrist in ulnar deviation also led to the largest extent of TD when compared to the other two hand activities of this study. Kinematic graphs showed that the motion pathways of median nerve during different hand activities were complex.

Conclusion

We observed that the median nerve in the carpal tunnel was rotated, deformed and displaced during the hand activities that people may be performed when using a smartphone, suggesting an increased risk of carpal tunnel syndrome (CTS). In addition, the kinematic graphs of median nerve developed in the present study provide new clues for further studies on the pathophysiology of CTS, and alerting smartphone users to establish proper postural habits when using handheld electronic devices.

Juvenile muscular atrophy of the distal upper extremities associated with x-linked periventricular heterotopia with features of Ehlers-Danlos syndrome

INTRODUCTION

Juvenile muscular atrophy of the distal upper extremities (JMADUE) is a rare, sporadic disorder that affects adolescent males and is characterized by progressive but self-limited weakness of the distal upper extremities. The etiology is unknown, but cervical hyperflexion has been hypothesized.

METHODS

We report a case of an adolescent male who presented with typical JMADUE but also had joint hypermobility and multiple congenital anomalies, including periventricular heterotopias, suggesting a multisystem syndrome.

RESULTS

Subsequent diagnostic testing confirmed a diagnosis of JMADUE, and sequencing of the filamin-A gene showed a novel, pathogenic mutation that confirmed an additional diagnosis of X-linked periventricular heterotopias with features of Ehlers-Danlos syndrome (XLPH-EDS).

CONCLUSIONS

The concurrent diagnosis of these 2 rare conditions suggests a pathogenic connection. It is likely that the joint hypermobility from XLPH-EDS predisposed this patient to developing JMADUE. This supports the cervical hyperflexion theory of pathogenesis. This case also expands the phenotype associated with FLNA mutations. Muscle Nerve 54: 794-797, 2016.

Sonographic features of peripheral nerves at multiple sites in patients with diabetic polyneuropathy

OBJECTIVE

Diabetic polyneuropathy (DPN) is one of the major complications of diabetes mellitus. Ultrasound has been frequently used for evaluation of peripheral nerves. However, there are few studies that have evaluated multiple peripheral nerves in DPN. In this study, ultrasonographic features of multiple peripheral nerves in upper and lower extremities of DPN patients were investigated and compared with those of healthy controls.

METHODS

This study was a case-control study that enrolled 20 patients with confirmed diagnosis of DPN and 20 healthy controls. The ultrasonography was performed on the sural, tibial, fibular, sciatic, median, ulnar, radial, and musculocutaneous nerves. Nerve cross-sectional area (CSA) was measured at multiple points for each peripheral nerve. The CSAs were compared between DPN and control groups, and analyzed in relation to the clinical characteristics and electrophysiologic findings.

RESULTS

The CSAs were significantly larger in the DPN group for sural nerve, fibular nerve at the fibular head level, median nerve at the carpal tunnel and mid-humerus level, ulnar nerve at the cubital tunnel outlet and mid-humerus level, and radial nerve at the spiral groove. The CSAs of sural nerve, tibial nerve and median nerve were significantly correlated with electrophysiologic findings. The sural nerve CSA revealed significant correlation with HbA1c.

CONCLUSIONS

These results suggest that the ultrasonography can provide useful information in diagnosis and evaluation of DPN.

High-Resolution Ultrasonography of the Superficial Peroneal Motor and Sural Sensory Nerves May Be a Non-invasive Approach to the Diagnosis of Vasculitic Neuropathy

High-resolution ultrasonography (HRUS) is an emerging new tool in the investigation of peripheral nerves. We set out to assess the utility of HRUS performed at lower extremity nerves in peripheral neuropathies. Nerves of 26 patients with polyneuropathies of different etiologies and 26 controls were investigated using HRUS. Patients underwent clinical, laboratory, electrophysiological assessment, and a diagnostic sural nerve biopsy as part of the routine work-up. HRUS was performed at the sural, tibial, and the common, superficial, and deep peroneal nerves. The superficial peroneal nerve longitudinal diameter (LD) distinguished best between the groups: patients with immune-mediated neuropathies (n = 13, including six with histology-proven vasculitic neuropathy) had larger LD compared to patients with non-immune-mediated neuropathies (p < 0.05) and to controls (p < 0.001). Among all subgroups, patients with vasculitic neuropathy showed the largest superficial peroneal nerve LD (p < 0.001) and had a larger sural nerve cross-sectional area when compared with disease controls (p < 0.001). Enlargement of the superficial peroneal and sural nerves as detected by HRUS may be a useful additional finding in the differential diagnosis of vasculitic and other immune-mediated neuropathies.

Proposed Sonographic Criteria for the Diagnosis of Idiopathic Tarsal Tunnel Syndrome

OBJECTIVE

To propose new sonographic criteria for the diagnosis of idiopathic tarsal tunnel syndrome (TTS).

DESIGN

Prospective case-control study.

SETTING

Academic referral center.

PARTICIPANTS

Adult healthy volunteers (n=17) and adult patients (n=14) with electrodiagnostically proven idiopathic TTS (mean age, 43.4±8.7y; height, 161.4±7.0cm; weight, 90.6±13.9kg) (N=31). The exclusion criteria were patients with diabetes, neurological disorders, associated ankle and/or foot disorders, electrodiagnostic evidence of a widespread lesion, or feet that were electrophysiologically negative for TTS or with structural abnormalities detected via ultrasound imaging.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Tibial nerve CSA at the proximal tarsal tunnel, tibial nerve CSA within the tunnel, within tunnel-to-proximal tunnel CSA ratio.

RESULTS

There was a significant difference in the within tunnel CSA and within tunnel-to-proximal tunnel CSA ratio between the TTS group and controls (P=.002 and P=.001, respectively). The optimum cutoff value was 19mm(2) for the within tunnel CSA and 1 for the within tunnel-to-proximal tunnel CSA ratio. Sensitivities were 61% and 74%, respectively.

CONCLUSIONS

The within tunnel-to-proximal tunnel CSA ratio and the within tunnel CSA are the most accurate sonographic parameters and can be helpful in the assessment of idiopathic TTS.

Ultrasonography of the peripheral nervous system in the early stage of Guillain-Barré syndrome

Ultrasonography can be used to visualize peripheral nerve abnormalities in immune-mediated neuropathies. The objective of this study was to prove the role of ultrasonography (US) in acute phase of Guillain-Barré syndrome (GBS). Systematic ultrasonic measurements of several peripheral nerves including the vagal nerve as well as the sixth cervical nerve root were performed in 18 patients with GBS at days 1-3 after symptom onset and compared to 21 healthy controls. Nerve conduction studies (NCS) of corresponding nerves were undertaken. Consequently, significant differences between the groups were found in compound muscle action potential amplitudes, F-wave latency, and persistency. Ultrasonic cross-sectional areas (CSAs) showed significant enlargement in all nerves except of the ulnar nerve (upper arm) and the sural nerve compared to healthy controls, most prominent in proximal and middle median nerve (p < 0.01). The vagal nerve also showed enlargement compared to controls (p < 0.05), which was most pronounced in patients with autonomic dysfunction compared to patients without (p < 0.05). C6 root diameter showed a significant correlation to the amount of cerebrospinal fluid (CSF)-protein (Pearson correlation, p < 0.05). US shows nerve enlargement in several peripheral nerves including vagal nerve and C6 root in acute phase of GBS and could be an additional diagnostic tool for example, in GBS of atypical onset and autonomic dysfunction.

Ultrasound in the diagnosis of peripheral neuropathy: structure meets function in the neuromuscular clinic

Peripheral nerve ultrasound (US) has emerged as a promising technique for the diagnosis of peripheral nerve disorders. While most experience with US has been reported in the context of nerve entrapment syndromes, the role of US in the diagnosis of peripheral neuropathy (PN) has recently been explored. Distinctive US findings have been reported in patients with hereditary, immune-mediated, infectious and axonal PN; US may add complementary information to neurophysiological studies in the diagnostic work-up of PN. This review describes the characteristic US findings in PN reported to date and a classification of abnormal nerve US patterns in PN is proposed. Closer scrutiny of nerve abnormalities beyond assessment of nerve calibre may allow for more accurate diagnostic classification of PN, as well as contribute to the understanding of the intersection of structure and function in PN.