Median Nerve Area Measurements Using Ultrasound: Importance of Proper Technique and Interpretation

Normative Values for the Sonographic Measurement of the Pediatric Median and Ulnar Nerves

RATIONAL AND OBJECTIVES

Ultrasound investigation of peripheral nerves, long used in the adult population, has been shown to be of value in diagnosing a variety of peripheral nerve abnormalities. More recently, nerve sonography has also been shown to be of use in pediatrics. However, normative values for nerve size in children have been lacking. As such, the goal of this research was to establish normative data for cross sectional area (CSA) measurements of the median and ulnar nerves in children.

MATERIALS AND METHODS

The median and ulnar nerves of 48 children ranging in age from 2 years to 17 years were imaged by ultrasound. CSA measurements were made at 2 separate sites for each nerve and measured independently by 6 pediatric radiologists. Reliability of ultrasound measurements between the radiologists was assessed by calculating intraclass correlation coefficients. Linear mixed-effects modeling was performed to develop prediction models for nerve cross sectional area for each nerve segment; 95% prediction values were generated from these models to approximate normal ranges.

RESULTS

Agreement in nerve cross-sectional area measurements among the 6 radiologists for all nerve segments was good (ICC 0.82, 95% CI 0.78 to 0.85). CSA for both the median and ulnar nerves is larger in older children. However, statistical models to predict CSA using height perform better rather than those using a child's age. The range of normal nerve segment CSA using these prediction models based on child height are reported.

CONCLUSION

Median and ulnar nerve CSA can be reliably measured with ultrasound. Normal reference values for ulnar and median nerve CSA correlate with patient age but may be more optimally determined based on a child's height.

Ultrasound-guided perineural vs. peritendinous corticosteroid injections in carpal tunnel syndrome: a randomized controlled trial

BACKGROUND

Corticosteroid injections are proven to be effective in the management of carpal tunnel syndrome (CTS); however, the optimal injection site still remains unclear.

AIM

To compare the efficacy of perineural vs. peritendinous target sites for corticosteroid injection in CTS.

DESIGN

A Randomized, Single-Blind, Controlled Trial.

SETTING

Outpatients, tertiary care center.

POPULATION

Forty-six patients were equally randomized into two intervention groups as Group A (18 F and 5 M, mean age;50.0 ± 15.9 years, mean symptom duration;5.9 ± 3.3 months) and Group B (19 F, 4 M patients, mean age;54.3 ± 15.0 years, mean symptom duration;5.9 ± 4.7 months).

METHODS

Methylprednisolone acetate (40 mg) and 1 mL of 1% trimecaine hydrochloride was injected next to the median nerve (Group A) or among flexor tendons away from the nerve (Group B) under ultrasound (US) guidance. The visual analogue scale was used as the primary outcome measure, and the symptom severity scale and functional status scale of the Boston Carpal Tunnel Questionnaire were used as the secondary subjective outcome measures. Twopoint discrimination, grip strength, cross-sectional area, and distal motor latency were assessed as objective outcome measures. The data were collected at baseline and at 2, 6 and 12 weeks after the injection.

RESULTS

Both groups showed improvement in subjective and objective measures at 2 weeks following the injection - also maintained up to 12 weeks during the follow-up (p<0.05). However, no difference was observed between the two groups (p<0.05). No serious adverse effects were observed in either group.

CONCLUSIONS

Both intervention techniques seem to be effective and safe in the conservative treatment of CTS.

CLINICAL REHABILITATION IMPACT

Based on this study results, it might be noteworthy that physicians can opt for perineural or peritendinous injections without compromising the treatment efficacy and safety. Herewith, US guidance is, for sure, necessary for performing safe and accurate injections.

Which Ultrasound Parameter Is More Accurate in the Diagnosis of Carpal Tunnel Syndrome: Cross-Sectional Area, Resistive Index, or Strain Ratio?

OBJECTIVE

The aim of this study was to compare the accuracy of cross-sectional area (CSA), resistive index (RI), and strain ratio (SR) in carpal tunnel syndrome (CTS).

DESIGN

This prospective and case-control study included patients with a diagnosis of CTS and a healthy control group. The participants were examined with an ultrasound Doppler system equipped with a high-resolution (5-18 MHz) linear probe (Philips L18-5). CSA, RI, and SR values were compared.

RESULTS

CSA, RI, and SR were found to be effective tools to detect the presence of CTS (regardless of severity). The cut-off value of 11.25 mm for CSA had a sensitivity and specificity of 97.2% and 88.0%, respectively. The cut-off value of 0.740 for RI had a sensitivity and specificity of 94.4% and 94.0%, respectively. The cut-off value of 1.95 for SR had a sensitivity and specificity of 97.2% and 84.0%, respectively. In respect of the severity of CTS, ultrasound was found to be an effective method to classify severe CTS cases only.

CONCLUSION

The CSA, SR, and RI seem to have excellent accuracy in the diagnosis of CTS. When the grading of severity is considered, ultrasound seems to be sensitive and specific in differentiating severe CTS cases from mild or moderate CTS cases.

Sonoelastographic evaluation of the sciatic nerve in patients with unilateral lumbar disc herniation

OBJECTIVE

The aim of this study was to compare strain elastography (SE) and shear wave elastography (SWE) findings of the sciatic nerve in patients with unilateral lumbar disc herniation (LDH) and healthy control subjects.

MATERIALS AND METHODS

The study group included patients with complaints of unilateral sciatica for 3-12 months, with foraminal stenosis due to one level of LDH (L4-L5 or L5-S1). An age- and gender-matched control group was formed of healthy subjects. Evaluations were performed on both the axial and longitudinal planes from the bilateral gluteal region using a 5-9 MHz multifrequency convex probe.

RESULTS

There were 40 patients (20 male, 20 female) with a mean age of 43.1 ± 12.7 years in the study group, and 40 healthy subjects (22 male, 18 female) with a mean age of 42.9 ± 10.7 years in the control group (p > 0.05). The sciatic nerve stiffness assessed on both the axial (12.3 ± 3.7 kPA) and longitudinal (14.3 ± 3.8 kPA) planes of the involved side was significantly higher than non-involved side (axial: 6.8 ± 2.1 and longitudinal: 8.3 ± 2.3 kPA) in the patient group (p < 0.001).

CONCLUSIONS

Patients with unilateral LDH have increased stiffness of the sciatic nerve compared to healthy control subjects. Although the findings in this preliminary study show that shear wave elastography can detect a change in sciatic nerve stiffness in patients with unilateral LDH, larger studies are required to determine the clinical utility of this technique.