Cross-sectional area reference values for nerve ultrasonography

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.