Reference values for nerve ultrasonography in the upper extremity

The Use of Neuromuscular Ultrasound and NCS/EMG Testing in the Differential Diagnosis of Carpal Tunnel Syndrome and Radiculopathy

BACKGROUND AND PURPOSE

The Neuromuscular ultrasound and Nerve conduction studies/Electromyography (NCS/EMG) are valuable diagnostic tools that examine and diagnose several nerve problems. The purpose of this case report is to describe a diagnostic electrophysiologic evaluation that differentiates between carpal tunnel syndrome (CTS) and radiculopathy in very mild or early stage cases.

CASE DESCRIPTION

The patient was a 30-year-old woman who sustained a tingling sensation in the second and third digits of her left hand, radiating pain in her left upper extremity and occasional neck pain. The patient cannot determine whether her radiating pain starts from the neck to her hand or starts from her hand up to the neck. Physical examination was not conclusive. Neuromuscular ultrasound and NCS/EMG were used to assess the median nerve at the carpal tunnel and the C6-7 nerve roots. A proof of the median nerve injury at the wrist was confirmed. The patient was treated with a night wrist splint.

OUTCOMES

The patient's symptoms were diminished after the use of the night splint for a period of approximately 4 weeks. A follow-up electrodiagnostic evaluation reveals improvement compared to the previous data with no electrophysiologic evidence of a current nerve injury status.

DISCUSSION

Neuromuscular ultrasound and NCS/EMG combined techniques helped in the differential diagnosis between CTS and C6-7 nerve roots radiculopathy. In this case, physical examination could not give an immediate conclusive answer.

Sonographic reference values of median nerve cross-sectional area: a protocol for a systematic review and meta-analysis

BACKGROUND

Median nerve cross-sectional area (CSA) is the primary sonographic parameter for assessing and diagnosing median nerve pathology, such as carpal tunnel syndrome. However, variability in the sensitivity of diagnostic thresholds exists, which may be due to a lack of standardized normative reference values. Current estimates of normal median nerve CSA stem largely from small studies using a local pool of healthy controls. A systematic review and meta-analysis will be conducted to identify all available data for median nerve CSA in healthy, asymptomatic individuals to create a comprehensive set of normative reference values.

METHODS

Articles that include sonographic measures of median nerve CSA will be identified through a rigorous search of published evidence, a hand search through tables of contents of key journals, and the gray literature, including ClinicalTrials.gov and conference abstracts. Each abstract and full text will be reviewed by multiple raters to identify studies from 2000 to present that include original data. Any study that provides median nerve CSA values from healthy individuals will be included (e.g., reference value study, control participants in a diagnostic study). Studies will be assessed for quality using a modified version of the National Institute of Health Study Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies, with primary focus on the use of a detailed and acceptable image acquisition and analysis protocol. Using data from included studies, reference values will be calculated for median nerve CSA by anatomical regions, including the distal forearm, wrist, and carpal tunnel at the level of the pisiform. Reference values will be stratified by gender, ethnicity, and age based upon the specificity of the data provided by the included articles.

DISCUSSION

A comprehensive set of normative reference values of median nerve CSA will reduce variability across studies, allowing future research to more accurately evaluate and establish diagnostic thresholds. Additionally, normative values can serve as a reference for evaluating treatment outcomes and provide a means to investigate and understand minor nuances in CSA changes that may be indicative of preclinical stages of median nerve pathology.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO 2016 CRD42016037286.

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.

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.

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.

Ultrasonographic Evaluation of the Radial Nerves in Patients with Unilateral Refractory Lateral Epicondylitis

Objective

To evaluate the possible radial nerve entrapment of patients with unilateral refractory lateral epicondylitis (LE) by using ultrasound (US) and electroneuromyography.

Design

Cross-sectional study.

Setting

Three physical medicine and rehabilitation departments.

Subjects

Consecutive 44 patients (15 M, 29 F) with unilateral refractory LE.

Methods

All patients underwent detailed clinical, electrophysiological and ultrasonographic evaluations. Ultrasound imaging was used to evaluate thickness and presence of abnormal findings of the common extensor tendon (CET) and cross-sectional area (CSA) of the radial nerve (at spiral groove and before bifurcation) bilaterally. Unaffected sides of the patients were taken as controls.

Results

When compared with the unaffected sides, CET thickness and radial nerve CSAs (at both levels) were higher, and abnormal US findings regarding LE (47.7% vs. 6.8%) were more common on the affected sides than nonaffected sides (all P  < 0.001). Grip strength values were lower on the affected sides ( P  < 0.001). Electrophysiological studies were all normal, and similar between the two sides (all P  > 0.05). When subgroup analyses were performed after taking into account the hand dominance, affected and dominant sides were found to be the same in 31 and different in 13 patients. In subgroups, CETs and radial nerve CSAs at both levels were higher on the affected sides (all P  < 0.01).

Conclusions

Radial nerves and the CETs seem to be swollen on the affected sides, independent from the hand dominance of the patients with refractory LE. These results morphologically support the previous literature that attributes some of the chronic complaints of these patients actually to radial nerve entrapment.

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.

Peripheral nerve atrophy together with higher cerebrospinal fluid progranulin indicate axonal damage in amyotrophic lateral sclerosis

INTRODUCTION

We aimed to investigate whether sonographic peripheral cross-sectional nerve area (CSA) and progranulin (PGRN), a neuritic growth factor, are related to each other and whether they interact to predict clinical and paraclinical measures in amyotrophic lateral sclerosis (ALS).

METHODS

We included 55 ALS patients who had forearm median and ulnar nerve CSA, cerebrospinal fluid (CSF) PGRN, and serum PGRN measures available. CSF PGRN was normalized against the CSF / serum albumin ratio (Q_alb ). Using age, sex, height, and weight adjusted general linear models, we examined CSA × CSF PGRN interaction effects on various measures.

RESULTS

There was a medium-effect size inverse relationship between CSA and CSF PGRN, but not between CSA and serum PGRN. Lower CSA values together with higher CSF PGRN levels were linked to smaller motor amplitudes.

DISCUSSION

In ALS, the constellation of peripheral nerve atrophy together with higher CSF PGRN levels indicates pronounced axonal damage. Muscle Nerve 57: 273-278, 2018.

Sonographic Findings of Polyneuropathy Associated With Cerebrotendinous Xanthomatosis: A Case Report

Cerebrotendinous xanthomatosis is a rare autosomal recessive disease that involves multiple organs, including the peripheral nervous system. The present study is the first to report the ultrasonographic findings of peripheral nerves in a patient with cerebrotendinous xanthomatosis. The patient presented with bilateral Achilles tendon enlargement and foot hypesthesia. Sonographic examination revealed hypoechoic, swollen peripheral nerves with enlarged bilateral Achilles tendons. Since the ultrasonographic findings revealed peripheral involvement, the diagnosis of cerebrotendinous xanthomatosis was established after laboratory and genetic studies along with clinical findings.

Optimal Radial Motor Nerve Conduction Study Using Ultrasound in Healthy Adults

Objective

To obtain reference values, to suggest optimal recording and stimulation site for radial motor nerve conduction study (RmNCS), and to analyze the correlation among RmNCS parameters, demographics and ultrasonography (US) findings.

Methods

A total of 55 volunteers participated in this study. We hypothesized that ‘lateral edge of spiral groove (A)’ was the optimal stimulation site, and the ‘largest cross-sectional area (CSA) of extensor indicis proprius (EIP) muscle (B)’ was the optimal recording site. The surface distance between ‘A’ and the lateral epicondyle of the humerus divided by upper arm length, was named the spiral groove ratio. The surface distance between ‘B’ and the ulnar styloid process divided by forearm length, was named the EIP ratio. Using US, we identified these sites, and further conducted RmNCS.

Results

Data was collected from 100 arms of the 55 volunteers. Mean amplitude and latency were 5.7±1.1 mV and 5.7±0.5 ms, respectively, at the spiral groove, and velocity between elbow and spiral groove was 73.7±7.0 m/s. RmNCS parameters correlated significantly with height, weight, arm length, and CSA of the EIP muscle. Spiral groove ratio and EIP ratio were 0.338±0.03 and 0.201±0.03, respectively; both values were almost the same, regardless of age, sex and handedness.

Conclusion

We established a reference value and standardized method of RmNCS using US. Optimal RmNCS can be conducted by placing the recording electrode 20% (about one-fifth) of forearm length from the ulnar styloid process, and stimulating at 34% (about one-third) of the humeral length from the lateral epicondyle.

Estimation of ultrasound reference values for the ulnar nerve fascicular number and cross-sectional area in young males: A cross-sectional study

The objective of this study is to estimate the reference values for the number of fascicles and cross-sectional area (CSA) of the ulnar nerve at a single predetermined site by ultrasound in healthy young adult males.The demographic and physical characteristics of 50 adult male volunteers were evaluated and recorded. The subjects were positioned supine with the elbow flexed at 90° and the palm of the hand placed on a hard surface. The ulnar nerve was scanned bilaterally 1 cm proximal to the medial epicondyle in projection of the cubital tunnel. The number of fascicles and mean CSA of the ulnar nerve were identified. 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.The mean fascicular number was 5.66 ± 1.48, the mean ultrasound-estimated CSA of the ulnar nerve was 6.54 ± 1.67 mm and both sides were comparable in the mean CSA and fascicular number (6.43 ± 1.80 mm and 5.88 vs 6.64 ± 1.55 mm and 5.44, for right and left side, respectively). No significant correlations were observed between CSA and fascicles number and age, weight, height, or BMI of study subjects.The reference values for the number of fascicles number and the CSA of the ulnar nerve at a single predetermined site were identified. These values could be used for the sonographic diagnosis and follow-up of the ulnar nerve lesions.

Ultrasonographic reference values for peripheral nerves and nerve roots in the normal population of children and adolescents: study protocol for an observational-prospective trial

BACKGROUND

High-resolution ultrasonography is a new and promising technique to evaluate peripheral and spinal nerves. Its validity as a diagnostic tool in neurological diseases has been demonstrated in adults. Up to now no reference values have been published in children and adolescents although this technique would be ideal in this population as it is fast and non-invasive.

METHODS/DESIGN

Our aim is to generate ultrasonographic reference values for several peripheral nerves (median, ulnar, radial, tibial, sural, peroneal and tibial nerve) as well as for the spinal nerves C5 and C6 and the vagus nerve in children and adolescents. In an observational prospective study, we will recruit 205 children and adolescents aged between ≥2 and ≤18 years without neuromuscular symptoms/signs and without a history of neuromuscular disease. After the collection of demographic and anthropometric data (height, weight, body mass index, age, gender and handedness) and a neurologic examination, a high-resolution ultrasonography of peripheral and spinal nerves at several anatomic landmarks will be performed. These data will be used to estimate age-dependent percentile curves and to evaluate inter-rater, intrarater and interequipment reliability of the measurements.

ETHICS AND DISSEMINATION

This study was approved by the local ethics committee (EKNZ 2015-210). The findings from this study will be disseminated through peer-reviewed publications and conference presentations.

TRIAL REGISTRATION NUMBER

NCT02570802, pre-results publication.

Physiological factors influencing median nerve mobility in normal subjects

INTRODUCTION

The purpose of this study was to assess the mobility of the median nerve in the axial plane in normal healthy subjects and to evaluate physiological factors associated with lesser degrees of mobility.

METHODS

Our study included 80 healthy volunteers between 20 and 60 years of age. For all subjects, mobility of the median nerve was assessed with ultrasound at the carpal tunnel.

RESULTS

With wrist and finger flexion, the median nerve moved in all 160 wrists; in 78, the nerve dove deep to the flexor tendons (full), and in 82 it made a partial turn, but did drop below the tendons (partial). Among all demographic factors and sonographic measurements, only height was significantly related to partial mobility.

CONCLUSIONS

Full or partial mobility of the median nerve with wrist flexion is an attribute of normal subjects; partial mobility is common, particularly in taller individuals. Muscle Nerve 54: 883-886, 2016.

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

INTRODUCTION

In this study we evaluated freehand 3D ultrasound (3DUS) of the median nerve in comparison to 2D ultrasound (2DUS) and assessed the influence of tilting the transversal plane on cross-sectional area (CSA) measurement.

METHODS

Two examiners investigated the median nerves of 22 healthy subjects over a distance of 20 cm using 3DUS. Image quality and CSA were assessed at random points within the virtual 3D volume and compared with 2DUS.

RESULTS

Image quality within the virtual 3D volume was good/sufficient/poor in 53.0%/40.2%/6.8% (examiner 1) and 21.6%/69.6%/8.8% (examiner 2), respectively. CSA measurements with 3DUS were smaller than with 2DUS (-12% and -17%; Wilcoxon test, P < 0.001). Interrater agreement for 3DUS and intermethod agreement between 2DUS and 3DUS were moderate. Stepwise tilting of the transversal plane increased CSA significantly.

CONCLUSION

Freehand 3DUS of the median nerve over 20 cm is feasible and may help overcome some of the limitations and pitfalls of 2DUS. Muscle Nerve 55: 206-212, 2017.

Ultrasound combined with electrodiagnosis improves lesion localization and outcome in posterior interosseous neuropathy

INTRODUCTION

Posterior interosseous nerve (PIN) syndrome is a rare compression neuropathy. Electrodiagnostic studies (EDx) combined with neuromuscular ultrasound (US) enable precise lesion localization and may improve patient outcome.

METHODS

In 4 patients with finger extension weakness, US was used to accurately localize concentric electromyographic (EMG) needle placement in PIN muscles and to visualize the lesion site.

RESULTS

EMG with US guidance showed decreased recruitment with abnormal configuration in PIN muscles. Active denervation was not always observed. US scanning demonstrated larger PIN diameter in the affected arm. All patients had surgical intervention to confirm EDx and US findings and had improved outcome on follow-up.

CONCLUSION

These cases demonstrate the benefits of augmenting EDx with US by guiding accurate electrode localization and providing diagnostic information about lesion location.

Diagnostic cutoff value for ultrasonography in the ulnar neuropathy at the elbow

Objective

To determine the diagnostic cutoff values of ultrasonographic measurements in ulnar neuropathy at the elbow (UNE).

Methods

Twenty-five elbows of 23 patients (9 females, 16 males) diagnosed with UNE and 30 elbows of 30 healthy controls (15 females, 15 males) were included in our study. The ulnar nerve cross-sectional area (CSA) was measured at the Guyon canal, midforearm, and maximal swelling point (MS) around the elbow (the cubital tunnel inlet in healthy controls). CSA measurements of the ulnar nerve at each point, the Guyon canal-to-MS ulnar nerve area ratio (MS/G), and the midforearm-to-MS ulnar nerve ratio (MS/F) were calculated.

Results

Among the variables, only CSA at MS, MS/G, and MS/F displayed significant differences between the control and patient groups. The cutoff value for diagnosing UNE was 8.95 mm² for the CSA at MS (sensitivity 93.8%, specificity 88.3%), 1.99 for the MS/G (sensitivity 75.0%, specificity 73.3%), and 1.48 for the MS/F (sensitivity 93.8%, specificity 95.0%).

Conclusion

These findings may be helpful to diagnose UNE.

Peripheral nerve ultrasound in amyotrophic lateral sclerosis phenotypes

INTRODUCTION

In this study we sought to determine the cross-sectional area (CSA) of peripheral nerves in patients with distinct subtypes of amyotrophic lateral sclerosis (ALS).

METHODS

Ulnar and median nerve ultrasound was performed in 78 ALS patients [classic, n = 21; upper motor neuron dominant (UMND), n = 14; lower motor neuron dominant (LMND), n = 20; bulbar, n = 15; primary lateral sclerosis (PLS), n = 8] and 18 matched healthy controls.

RESULTS

Compared with controls, ALS patients had significant, distally pronounced reductions of ulnar CSA (forearm/wrist level) across all disease groups, except for PLS. Median nerve CSA (forearm/wrist level) did not differ between controls and ALS.

CONCLUSION

Ulnar nerve ultrasound in ALS subgroups revealed significant differences in distal CSA values, which suggests it has value as a marker of LMN involvement. Its potential was particularly evident in the UMND and PLS groups, which can be hard to separate clinically, yet their accurate separation has major prognostic implications.

Ultrasound-guided lateral femoral cutaneous nerve conduction study

Objective

To verify the utility of the lateral femoral cutaneous nerve (LFCN) ultrasound-guided conduction technique compared to that of the conventional nerve conduction technique.

Methods

Fifty-eight legs of 29 healthy participants (18 males and 11 females; mean age, 42.7±14.9 years) were recruited. The conventional technique was performed bilaterally. The LFCN was localized by ultrasound. Cross-sectional area (CSA) of the LFCN and the distance between the anterior superior iliac spine (ASIS) and the LFCN was measured. The nerve conduction study was repeated with the corrected cathode location. Sensory nerve action potential (SNAP) amplitudes of the LFCN were recorded and compared between the ultrasound-guided and conventional techniques.

Results

Mean body mass index of the participants was 23.7±3.5 kg/m², CSA was 4.2±1.9 mm², and the distance between the ASIS and LFCN was 5.6±1.7 mm. The mean amplitude values were 6.07±0.52 µV and 6.66±0.54 µV using the conventional and ultrasound-guided techniques, respectively. The SNAP amplitude of the LFCN using the ultrasound-guided technique was significantly larger than that recorded using the conventional technique.

Conclusion

Correcting the stimulation position using the ultrasound-guided technique helped obtain increased SNAP amplitude.

Carpal tunnel syndrome assessment with ultrasonography: value of inlet-to-outlet median nerve area ratio in patients versus healthy volunteers

Objective

To evaluate the diagnostic value of the Inlet-to-outlet median nerve area ratio (IOR) in patients with clinically and electrophysiologically confirmed carpal tunnel syndrome (CTS).

Methods

Forty-six wrists in 46 consecutive patients with clinical and electrodiagnostic evidence of CTS and forty-four wrists in 44 healthy volunteers were examined with ultrasonography. The cross-sectional area (CSA) of the median nerve was measured at the carpal tunnel inlet (the level of scaphoid-pisiform) and outlet (the level of the hook of the hamate), and the IOR was calculated for each wrist. Ultrasonography and electrodiagnostic tests were performed under blinded conditions. Electrodiagnostic testing combined with clinical symptoms were considered to be the gold standard test. Receiver operating characteristic (ROC) curves were used to evaluate the diagnostic value between the inlet CSA and IOR.

Results

The study population included 16 men and 30 women (mean age, 45.3 years; range, 18–83 years). The control population included 18 men and 26 women (mean age, 50.4 years; range, 18–79 years). The mean inlet CSA was 8.7 mm² in healthy controls and 14.6mm² in CTS group (P<0.001). The mean IOR in healthy volunteers (1.0) was smaller than that in patients (1.6, P<0.001). Receiver operating characteristic analysis revealed a diagnostic advantage to using the IOR rather than the inlet CSA (P<0.01). An IOR cutoff value of ≥ 1.3 would yield 93% specificity and 91% sensitivity in the diagnosis of CTS.

Conclusion

The IOR of median nerve area promises to be an effective means in the diagnosis of CTS. A large-scale, randomized controlled trial is required to determine how and when this parameter will be used.

The effect of magnification on sonographically measured nerve cross-sectional area

INTRODUCTION

The primary aim of this investigation was to determine whether use of write-zoom magnification affects sonographically determined cross-sectional area (CSA) of peripheral nerves.

METHODS

CSAs of the median (MN) and posterior interosseous (PIN) nerves were measured in 22 limbs from 11 asymptomatic volunteers using both standard imaging and write-zoom magnification. CSA measurements were repeated on the same images 1 week later.

RESULTS

The average CSA of write-zoomed images for the MN was significantly larger at both measurement sessions (week 1: 11.1 mm(2) write-zoom vs. 10.0 mm(2) standard, P = 0.019; week 2: 11.8 mm(2) vs. 10.4 mm(2), P = 0.023). Similar differences were noted for the PIN (week 1: 2.3 mm(2) vs. 1.9 mm(2), P = 0.002; week 2: 2.5 mm(2) vs. 1.9 mm(2), P = 0.001).

CONCLUSIONS

Write-zoom magnification may significantly increase the measured CSA of peripheral nerves. These changes appear to be more substantial when smaller nerves are measured.

Anatomical and ultrasound correlation of the superficial branch of the radial nerve

INTRODUCTION

This anatomical study evaluates the role and correlation of ultrasound (US) with anatomy in depicting the superficial branch of the radial nerve (SBRN) and to evaluate the feasibility of US guided perineural infiltration as a potential therapeutic option in Wartenberg syndrome.

METHODS

Twenty-one arms from 11 non-embalmed cadavers were examined with US. Under US guidance perineural injection with ink was performed proximal to the site where the SBRN perforates the forearm fascia. The distribution of ink around the nerve was evaluated with dissection.

RESULTS

US allowed the distinction of the SBRN segments and their relation to the fascia. In all cases, the subfascial segment was stained. In only 57% the subfascially applied ink also reached the subcutaneous compartment.

CONCLUSIONS

With US it is possible to examine and differentiate all segments of the SBRN. US guidance can be used for perineural injection of all relevant segments.

Cross-sectional area reference values of nerves in the lower extremities using ultrasonography

INTRODUCTION

Cross-sectional area (CSA) reference values of lower extremity nerves using ultrasonography have only been reported in a few studies and have been limited to white populations.

METHODS

For this study, 94 healthy Korean volunteers were recruited for measurement of the CSA at 7 sites of lower extremity nerves. The side-to-side difference in CSA was calculated for each nerve, and reference ranges were derived. External validity evaluation for the reference values was performed with 10 newly recruited volunteers at a different institution.

RESULTS

Nerve CSA was correlated significantly with body mass index, weight, and height; however, the absolute value of the side-to-side difference had no significant correlation with demographic factors. The external validity was adequate for all sites, ranging from 80% to 100%.

CONCLUSIONS

The lower extremity nerve CSA values obtained in this study may provide normal reference values for the Asian population.

Ultrasonographic findings of superficial radial nerve and cephalic vein

OBJECTIVE

To investigate the anatomic relationship between the superficial radial nerve (SRN) and the cephalic vein (CV) through ultrasonography due to the possibility of SRN injury during cephalic venipuncture.

METHODS

Both forearms of 51 healthy volunteers with no history of trauma or surgery were examined in proximal to distal direction using ultrasonography. We measured the distance between the radial styloid process (RSP) and the point where the SRN begins contact with the CV, and measured the distance between the RSP and the point where the SRN is separated from the CV. The point where the SRN penetrates the brachioradialis fascia was also evaluated.

RESULTS

The SRN came in contact with the CV at a mean of 9.35±1.05 cm from the RSP and separated from the CV at a mean of 6.29±1.17 cm from the RSP. The SRN pierced the brachioradialis fascia at a mean of 10.31±0.89 cm from the RSP and horizontally 1.35±0.36 cm medial to the radius margin. All parameters had no significant differences in gender or direction.

CONCLUSION

The SRN had close approximation to the CV in the distal second quarter of the forearm. We recommend for cephalic venipuncture to be avoided in this area, and, if needed, it should be carried out with care not to cause injury to the SRN.

Thinning of cervical nerve roots and peripheral nerves in ALS as measured by sonography

OBJECTIVE

Progressive atrophy and loss of motor axons is a hallmark of amyotrophic lateral sclerosis (ALS). Limited sonographic data are available on potential detection of atrophy of peripheral nerves and nerve roots in ALS.

METHODS

Patients with either definite or probable ALS and control subjects underwent sonographic evaluation of the cervical roots (C5, C6, and C7) and peripheral nerves (median and ulnar nerves) on the right. These diameters and cross-sectional areas (C6, median, and ulnar nerves) were compared.

RESULTS

The diameters and cross-sectional areas were consistently smaller in ALS than in controls. No correlation was present between the sonographic parameters and the disease severity, disease duration, age, or gender. The overall sensitivity and specificity tended to be greater in the cervical nerve roots than in the peripheral nerves.

CONCLUSIONS

This study shows atrophy of cervical nerve roots and peripheral nerves in ALS detected by sonography. Cervical nerve roots might be more appropriate to detect motor axon loss than peripheral nerves.

SIGNIFICANCE

Sonographic evaluation of nerve roots and peripheral nerves may be a useful disease marker in ALS to confirm the diagnosis and to potentially monitor the disease progression.

Pattern analysis of nerve enlargement using ultrasonography in chronic inflammatory demyelinating polyneuropathy

OBJECTIVE

Focal nerve enlargement is a characteristic finding in chronic inflammatory demyelinating polyneuropathy (CIDP). We performed this study to assess the distribution of nerve enlargement through ultrasonographic examination of peripheral nerves and to correlate the ultrasonographic findings with clinical features.

METHODS

To compare the ultrasonographic features of 10 subjects with CIDP with those of 18 healthy controls, we bilaterally measured the cross-sectional areas (CSA) of the vagus, brachial plexus, musculocutaneous, median, ulnar, radial, sciatic, tibial, common peroneal, and sural nerves. We also analyzed correlations between CSAs and various clinical and electrophysiological features.

RESULTS

Mean CSAs were significantly larger in CIDP patients than controls, especially at proximal and non-entrapment sites. CSAs were significantly correlated with muscle strength at initial presentation, but not at the time of ultrasonography. The CSAs of the median and ulnar nerves at the mid-forearm, tibial nerve at 7 cm proximal to the medial malleolus, and sural nerve correlated with the nerve conduction velocity of the corresponding region.

CONCLUSION

Ultrasonography revealed widely distributed nerve enlargement, especially in proximal regions and non-entrapment sites, in patients with CIDP compared with healthy controls. Nerve enlargement correlated well with the electrophysiologic function of the nerve, but not current clinical status.

SIGNIFICANCE

Pattern analysis of nerve enlargement using ultrasonography is a supportive tool in the diagnosis of CIDP.