Cross-sectional area reference values for nerve ultrasonography

Reliability of side-to-side ultrasound cross-sectional area measurements of lower extremity nerves in healthy subjects

INTRODUCTION

In peripheral nerve ultrasound, the healthy contralateral side may be used as internal control. Therefore, inherent side-to-side differences must be minimal. The goal of this study was to assess intrastudy, intraobserver, and interobserver reproducibility of ultrasound in comparative side-to-side evaluation of lower limb nerves.

METHODS

Lower limb nerves of 60 normal subjects were evaluated by 3 radiologists. Bilateral sciatic, tibial, common fibular, sural, lateral femoral cutaneous, femoral, obturator, and saphenous nerves were evaluated.

RESULTS

Overall, side-to-side differences were not statistically significant at any level. In the lower limb nerves, in a between-limb comparison, the minimum detectable difference of cross-sectional area ranged from 16.4 mm(2) (sciatic nerve at the level of piriformis muscle) to 0.4 mm(2) (saphenous nerve).

CONCLUSION

In general, the healthy contralateral side can be used as an internal control.

Measurement of cross-sectional area of cervical roots and brachial plexus trunks

INTRODUCTION

The aim of this study was to determine normal reference values for cross-sectional area (CSA) and the correlation between demographic factors and CSA in the cervical roots and brachial plexus trunks using ultrasonography.

METHODS

Ninety-five age-matched healthy individuals were studied. Ultrasonographic tests were performed via nerve tracing from the cervical root to the brachial plexus trunk. The CSA of each nerve was measured in the C5-8 ventral roots and brachial plexus (trunk level).

RESULTS

Normal values of each cervical root were: C5, 5.66 ± 1.02 mm(2); C6, 8.98 ± 1.65 mm(2); C7, 10.43 ± 1.86 mm(2); and C8, 10.76 ± 2.02 mm(2). Values for the brachial plexus were: upper trunk, 16.70 ± 2.88 mm(2); middle trunk, 14.01 ± 2.70 mm(2); and lower trunk, 13.75 ± 2.57 mm(2). The side-to-side discrepancy was 11.91 ± 11.11%. Body mass index (BMI) and height correlated frequently with nerve CSA.

CONCLUSIONS

These reference values may be helpful in investigating pathologies involving the cervical area.

Can ultrasound of the tibial nerve detect diabetic peripheral neuropathy? A cross-sectional study

OBJECTIVE

Peripheral nerve imaging by portable ultrasound (US) may serve as a noninvasive and lower-cost alternative to nerve conduction studies (NCS) for diagnosis and staging of diabetic sensorimotor polyneuropathy (DSP). We aimed to examine the association between the size of the posterior tibial nerve (PTN) and the presence and severity of DSP.

RESEARCH DESIGN AND METHODS

We performed a cross-sectional study of 98 consecutive diabetic patients classified by NCS as subjects with DSP or control subjects. Severity was determined using the Toronto Clinical Neuropathy Score. A masked expert sonographer measured the cross-sectional area (CSA) of the PTN at 1, 3, and 5 cm proximal to the medial malleolus.

RESULTS

Fifty-five patients had DSP. The mean CSA of the PTN in DSP compared with control subjects at distances of 1 (23.03 vs. 17.72 mm(2); P = 0.004), 3 (22.59 vs. 17.69 mm(2); P < 0.0001), and 5 cm (22.05 vs. 17.25 mm(2); P = 0.0005) proximal to the medial malleolus was significantly larger. Although the area under the curve (AUC) for CSA measurements at all three anatomical levels was similar, the CSA measured at 3 cm above the medial malleolus had an optimal threshold value for identification of DSP (19.01 mm(2)) with a sensitivity of 0.69 and a specificity of 0.77 by AUC analysis.

CONCLUSIONS

This large study of diabetic patients confirms that the CSA of the PTN is larger in patients with DSP than in control subjects, and US is a promising point-of-care screening tool for DSP.

Diagnostic value of ultrasonography and magnetic resonance imaging in ulnar neuropathy at the elbow

Aim. To evaluate the diagnostic value of ultrasonography and magnetic resonance imaging (MRI) in patients with ulnar neuropathy at the elbow (UNE). Methods. We prospectively performed electrodiagnostic, ultrasonographic, and MRI studies in UNE patients and healthy controls. Three cross-sectional area (CSA) measurements of the ulnar nerve at multiple levels along the arm and maximum CSA(-max) were recorded. Results. The ulnar nerve CSA measurements were different between the UNE severity grades (P < 0.05). CSA-max had the greatest sensitivity (93%) and specificity (68%). Moreover, CSA-max ≥10 mm² defined the severe UNE cases (sensitivity/specificity: 82%/72%). In MRI, ulnar nerve hyperintensity had the greatest sensitivity (90%) and specificity (80%). Conclusion. Ultrasonography using CSA-max is sensitive and specific in UNE diagnosis and discriminating the severe UNE cases. Furthermore, MRI particularly targeting at increased signal of the ulnar nerve can be a useful diagnostic test of UNE.

Ultrasonography in the diagnosis of peripheral nerve disease

INTRODUCTION

High-resolution ultrasound (US) of the peripheral nerves is now a standard means of assessing neuromuscular disorders in many centers. Currently used in conjunction with electrodiagnostic (EDX) studies, nerve US is especially effective in the diagnosis of entrapment neuropathies.

AREAS COVERED

This article reviews the basic physics of peripheral nerve US, guidelines for its current use and future directions. Advantages of using nerve US alongside EDX studies are outlined along with current limitations of testing. The role of US in the diagnosis of entrapment neuropathy is emphasized, particularly in carpal tunnel syndrome (CTS). US assisted diagnosis of peripheral nerve tumors, hereditary neuropathy and dysimmune neuropathy and traumatic injuries is also described.

EXPERT OPINION

US is a powerful tool in the assessment of peripheral nerve disease. Nerve US is an evolving, young discipline. There is still much to learn, but current evidence supports US imaging of all patients presenting for evaluation of possible mononeuropathy. With improvements in resolution, the introduction of US contrast agents and objective measures of nerve echogenicity, there is promise for further expanding its role in the diagnosis of all peripheral neuropathies.

Preliminary evaluation of the sural nerve using 22-MHz ultrasound: a new approach for evaluation of diabetic cutaneous neuropathy

BACKGROUND

The application of 22-MHz high-frequency ultrasound allows for visualization of the inner part of the sural nerve. The aim of this study was to evaluate the morphological changes of sural nerves in patients with type 2 diabetes mellitus using ultrasound.

MATERIALS AND METHODS

The thickness/width (T/W) ratio, the cross-sectional area (CSA) of the sural nerves and the maximum thickness (MT) of the nerve fascicles were measured in 100 patients with type 2 diabetes mellitus and 50 healthy volunteers using 22-MHz ultrasound. Receiver operating characteristic (ROC) curves were plotted to determine the optimal cut-off values as well as the sensitivities and specificities. All parameters were significantly different between the subject and control groups. The ROC curves demonstrated that the MT was the most predictive of diabetic cutaneous neuropathy, with an optimal cut-off value of 0.365 mm that yielded a sensitivity of 90.3% and a specificity of 87.7%.

CONCLUSIONS

The results of this study suggest that 22-MHz ultrasound may be a valuable tool for evaluating diabetic cutaneous nerve neuropathy.

Sonographic features in hereditary neuropathy with liability to pressure palsies

INTRODUCTION

Diagnostic nerve ultrasound is becoming more commonly used by both radiologists and clinicians. The features of different neuromuscular conditions must be described to broaden our understanding and ability to interpret findings.

METHODS

Our study examines the sonographic features of 7 subjects with hereditary neuropathy with liability to pressure palsies (HNPP) in comparison to 32 controls by measuring the nerve cross-sectional area (CSA) of the median, ulnar and tibial nerves.

RESULTS

Significant differences (P < 0.05) in nerve size were found. The HNPP group had a larger CSA for the median nerve at the wrist and ulnar nerve at the elbow (entrapment sites), but not the forearms. The tibial nerve at the ankle was also larger in the HNPP group, suggesting possible concomitant tibial neuropathy at the ankle.

CONCLUSION

These results will help shape imaging protocols to better detect conditions with non-uniform nerve enlargements.

Peripheral nerve and muscle ultrasound in amyotrophic lateral sclerosis

INTRODUCTION

High-resolution ultrasound has been used to evaluate several neuromuscular conditions, but it has only been used on a limited basis in amyotrophic lateral sclerosis (ALS) patients. It has not been used to assess their peripheral nerves. This study was designed to use neuromuscular ultrasound to investigate nerve cross-sectional area and muscle thickness in ALS.

METHODS

Twenty individuals with ALS and 20 matched controls underwent neuromuscular ultrasound to measure the cross-sectional area of their median and sural nerves and the thickness of their biceps/brachialis muscle complex.

RESULTS

The cross-sectional area of the median nerve in the mid-arm was smaller in the ALS group than in controls (10.5 mm(2) vs. 12.7 mm(2) , P = 0.0023), but no difference was seen in the sural nerve (4.5 mm(2) vs. 5.0 mm(2) , P = 0.1927). The ALS group also had thinner biceps/brachialis than controls (2.1 cm vs. 2.9 cm, P = 0.0007).

CONCLUSIONS

Neuromuscular ultrasound demonstrates nerve and muscle atrophy in ALS and should be further explored as a disease biomarker.

Ultrasonography in ulnar neuropathy at the elbow: a critical review

INTRODUCTION

Ultrasonography of the ulnar nerve has been recommended as a useful additional test in ulnar neuropathy at the elbow (UNE).

METHODS

We searched the literature and systemically reviewed all clinical trials in UNE. We also looked for articles about the normal sonoanatomy and specific causes of UNE.

RESULTS

Seven of 14 clinical trials in UNE were suitable for further analysis. Ultrasonographic ulnar nerve size measurement appears to be a test with good diagnostic accuracy. The most frequently reported abnormality was an increased cross-sectional area of the ulnar nerve at the elbow. However, several studies had methodological flaws. In addition, the ultrasonographic techniques and study designs differed among the studies. There were a few other uncontrolled studies about the underlying causes of UNE.

DISCUSSION

The role of ultrasonography in UNE seems promising but could not be firmly established. More prospective studies are needed, and we make several recommendations for further research.

Contribution of ultrasound in the assessment of nerve diseases

BACKGROUND AND PURPOSE

Recently, ultrasound (US) has been used to assess the peripheral nervous system; however, there is no real study about its possible significant role in routine practice. Our study aims to assess the contribution of US as a routine tool in a neurophysiological laboratory.

METHODS

The study assesses 130 patients who presented clinical suspicion of peripheral nerve diseases, excluding motor neuron disease, radiculopathy, hereditary and acquired polyneuropathy. All patients were clinically, neurophysiologically and sonographically assessed in the same session by the same neurologist/neurophysiologist. To avoid interpretation bias, two independent and blinded clinicians, different than the examiners performing electrodiagnosis and US, reviewed clinical, neurophysiological and US findings (also data about follow-up, when available) and classified the contribution of US as follows: Contributive (US had influence on the diagnostic and therapeutic strategies), Confirming (US confirmed the clinical and neurophysiological diagnosis), Non-Confirming (US findings were normal) and Incorrect (US findings led to incorrect diagnosis).

RESULTS

US impacted, namely modified the diagnostic and therapeutic path in 42.3% of cases (55 patients); US had a confirmatory role in 40% (52 patients); US did not confirm clinical and neurophysiological diagnosis in 17.7% (23 cases); no incorrect US findings were observed.

CONCLUSION

US complements neurophysiological assessment even in routine practice, and this confirms the increasing interest in US for a multidimensional evaluation of peripheral nerve system diseases.

US imaging of the musculocutaneous nerve

PURPOSE

To describe the potential value of high-resolution sonography for evaluation of the musculocutaneous nerve (MCN).

MATERIALS AND METHODS

The normal anatomy of the MCN was evaluated on three cadaveric limbs and correlated with the US images obtained in 15 healthy subjects. Seven consecutive patients with MCN neuropathy were then evaluated with sonography using 17.5 and 12.5-MHz broadband linear array transducers. All patients had abnormal nerve conduction studies and underwent correlative MR imaging on a 1.5-T system.

RESULTS

One-to-one comparison between cadaveric specimens and sonographic images showed that the MCN can be reliably identified from the axilla through the elbow, including the lateral antebrachial cutaneous (LAbC) nerve. In the patients group with MCN neuropathy, sonography allowed detection of a wide spectrum of abnormalities. In 5/7 cases, a spindle neuroma was depicted in continuity with the nerve. In one case, US identified focal swelling of the nerve and in another case US was negative. The neuroma was hyperintense on T2-weighted sequences in 75% of cases. In one patient, the nerve showed Gd-enhancement on fat-suppressed T1-weighted sequences. The nerve was never detected on unenhanced T1-scans. Owing to its small-size and out-of-plane course, the MCN may be more reliably depicted with sonography rather than with MR imaging.

CONCLUSIONS

US is promising for evaluating traumatic injuries of the MCN. By providing unique information on the entire course of the nerve, US can be used as a valuable complement of clinical and electrophysiologic findings.

Normative cross-sectional area of the C5-C8 nerve roots using ultrasonography

This study will define a normal range of values for the cross-sectional area (CSA) of the C5-C8 ventral rami in normal subjects and will assess the interexaminer reliability of the CSA measurements. We also describe the normal sonoanatomy of the C5-C8 ventral rami. Thirty-three normal subjects (20 female) were scanned bilaterally. The mean CSA and reference ranges for the C5, C6, C7 and C8 ventral rami were 7.1 +/- 4.1 mm(2), 10.6 +/- 4.3 mm(2), 12.1 +/- 4.1 mm(2) and 10.7 +/- 4.8 mm(2), respectively. The intraclass correlation coefficient (ICC) demonstrated good reliability with a coefficient of 0.76 overall, with individual level coefficients at C5, C6, C7 and C8 of 0.69, 0.71, 0.76 and 0.72, respectively. This is the first study to obtain normative CSA measurements of the C5-C8 ventral rami.

Sonographic evaluation of the peripheral nerve in diabetic patients: the relationship between nerve conduction studies, echo intensity, and cross-sectional area

OBJECTIVE

Early detection of nerve dysfunction is important to provide appropriate care for patients with diabetic polyneuropathy. The aim of this study was to assess the echo intensity of the peripheral nerve and to evaluate the relationship between nerve conduction study results and sonographic findings in patients with type 2 diabetes mellitus.

METHODS

Thirty patients with type 2 diabetes (mean +/- SD, 59.8 +/- 10.2 years) and 32 healthy volunteers (mean, 53.7 +/- 13.9 years) were enrolled in this study. The cross-sectional area (CSA) and echo intensity of the peripheral nerve were evaluated at the carpal tunnel and proximal to the wrist (wrist) of the median nerve and in the tibial nerve at the ankle.

RESULTS

There was a significant increase in the CSA and hypoechoic area of the nerve in diabetic patients compared with controls (wrist, 7.1 +/- 2.0 mm(2), 62.3% +/- 3.0%; ankle, 8.9 +/- 2.8 mm(2), 57.6% +/- 3.9%; and wrist, 9.8 +/- 3.7 mm(2), 72.3% +/- 6.6%; ankle, 15.0 +/- 6.1 mm(2), 61.4% +/- 5.3% in controls and diabetic patients, respectively; P < .05). Cross-sectional areas were negatively correlated with reduced motor nerve conduction velocity and delayed latency.

CONCLUSIONS

These results suggest that sonographic examinations are useful for the diagnosis of diabetic neuropathy.

Peripheral nerve size in normals and patients with polyneuropathy: an ultrasound study

Ultrasound has been used for visualizing peripheral nerve pathology. Our goal was to use ultrasound to quantitate the sizes of upper extremity nerves along their length in control subjects and patients with neuropathy. We measured median and ulnar nerve cross-sectional areas (NCSA) in the arms of 190 subjects, including 100 with neuropathies and 90 controls. We found that NCSAs in healthy child and adult controls were greater with increasing height, at proximal sites, and at sites of entrapment. Nerves were enlarged in all Charcot-Marie-Tooth 1A (CMT-1A) (11 of 11; 100%), most chronic inflammatory demyelinating polyneuropathy (CIDP) (31 of 36; 86%), half of Guillain-Barré syndrome (GBS) (8 of 17; 47%), but few axonal neuropathy (7 of 36, 19%) subjects. In GBS, nerve enlargement occurred early and with minimal electrodiagnostic abnormalities in some patients. We conclude that NCSA measured by ultrasound is a quantifiable marker of nerve features that should be corrected for patient characteristics and nerve site. NCSA is generally larger in demyelinating than it is in axonal polyneuropathies.

Ultrasonographic swelling ratio in the diagnosis of ulnar neuropathy at the elbow

High-resolution ultrasound can demonstrate focal nerve enlargement in entrapment neuropathies. We hypothesized that a ratio between the nerve cross-sectional area at the site of maximal enlargement and at an unaffected site may improve diagnostic accuracy in ulnar neuropathy at the elbow (UNE), when compared to a single measurement at the site of maximal enlargement. Ultrasound was used to measure the cross-sectional area of the ulnar nerve at three sites in 30 normal, healthy controls and 26 individuals with UNE. In individuals with UNE, the ratio was 2.9:1 when the site of maximal swelling was compared with a distal ulnar nerve site and 2.8:1 when compared with a proximal site. This represented a significant increase compared with the ratio of 1.1:1 for both comparisons in controls (P < 0.0001). This type of ratio may be particularly useful for assessing entrapment in those with polyneuropathy or obesity, both of which can cause diffuse nerve enlargement.