Change in cross-sectional area of the median nerve with age in neonates, infants and children analyzed by high-resolution ultrasound imaging

Nerve cross-sectional area from childhood to old age: A high-resolution nerve ultrasound study

BACKGROUND AND PURPOSE

Nerve cross-sectional area (CSA) is not constant over the human lifespan. The relationship between an increasing CSA and age has been described as a linear positive correlation, but few studies have found a linear decrease in nerve size with older age. The aim of the present study was to analyze the development of nerve CSA in a healthy population from early childhood to old age using high-resolution ultrasound.

METHODS

The median, ulnar, radial and sural nerves were examined bilaterally at 18 nerve sites in 110 healthy children, adolescents and adults aged between 2 and 98 years. The CSA of every nerve site was evaluated separately and in different age groups. The correlation of CSA with age, height and weight was analyzed in a linear, logarithmic and quadratic model and correlation coefficients were compared in a goodness-of-fit analysis. Models were then adjusted for weight and height.

RESULTS

Linear CSA-age correlations showed the lowest correlation coefficients for all nerve sites. An inverted parabolic curve suggesting a quadratic correlation of CSA and age was the best-fitting model. Weight and height had a higher predictive value than age in adjusted models.

CONCLUSIONS

There is an increase in nerve size during childhood and adolescence and a trend towards a decrease in old age, suggesting an inverted parabolic curve partly explained by age-related changes in weight and height. Enlarged nerves in elderly individuals should not be attributed to age alone.

Nerve ultrasound reference values in children and adolescents: Echogenicity and influence of anthropometric factors including hand volume

Background

Nerve cross-sectional area (CSA) reference values in high-resolution ultrasound for children and adolescents are influenced by demographic and anthropometric factors such as age, height and weight.

Objectives

The influence of hand volume as an additional morphometric factor was evaluated and nerve echogenicity was analyzed in a prospective cross-sectional study.

Methods

CSA were measured in 30 healthy children and adolescents from 2 to 17 years in the median, ulnar, radial, tibial, peroneal and sural nerves. Height, weight, age, handedness and gender were recorded, the volume of the hands was measured using the water displacement method. The intra-nerve CSA variability (INV), left/right ratios and absolute differences were calculated. Age groups were compared by the Kruskal-Wallis test. The influence of demographic factors was analyzed using Spearman correlation and multiple linear regression. Echogenicity and fraction of black were determined for each nerve segment.

Results

Nerve CSA values were consistently lower than those reported for adults and correlated in all measured nerve sites with age, height, weight and hand volume. Weight showed the highest correlation coefficient (R = .95) with the best fitting model predicting CSA. Correlation coefficients were higher in a linear than in a logarithmic model. Ratios were stable, the absolute differences increased with age and were significantly different between age groups. Most nerves showed a mixed or hypoechogenic pattern in echogenicity analysis, hyperechogenicity is less frequently observed.

Conclusions

Nerve CSA in children and adolescents is lower than in adults and increases proportionally during growth with a constant INV and left/right ratio in different age groups. Weight and age are predominant anthropometric factors predicting nerve size. Hand volume is correlated with nerve size, but does not predict CSA independently. Echogenicity can provide additional information on nerve structure.

Correlation between age and the sciatic nerve diameter in the first 2 years of life: A high-resolution ultrasound study

AIM

To investigate the maturation of the peripheral nervous system by analyzing the cross-sectional area of the sciatic nerve during the first 2 years of life.

METHODS

The sciatic nerve was examined by high-resolution ultrasound imaging in 52 children aged 0 days to 10 years, 45 of whom were younger than 2 years. The correlation between the cross-sectional area of the nerve and the age was statistically tested. A logarithmic regression analysis was performed to develop a logarithmic growth model of the cross-sectional area.

RESULTS

There is a highly significant correlation between the age and the cross-sectional area of the sciatic nerve. The growth rate can well be described by a logarithmic model.

INTERPRETATION

Based on the literature on the maturation of the median nerve and nerve roots and the findings of the present study, we conclude that both the proximal and the distal parts of the nerves of the peripheral nervous system increase simultaneously.

WHAT THIS PAPER ADDS

Normative values for the size of the sciatic nerve in children.

Sonographic reference values of nerve size in children: A systematic review and meta-analysis

INTRODUCTION/AIMS

Nerve ultrasound is useful in the diagnosis and follow-up of peripheral nerve disorders in children. The aim of this study was to explore and analyze the current literature on nerve cross-sectional area (CSA) in healthy children, with the goal of presenting reference values and discussing their implications.

METHODS

We performed a systematic review and meta-analysis of studies that reported ultrasound measurements of the upper or lower limb nerves in healthy children through a search of Web of Science, PubMed, Embase, and Scopus.

RESULTS

Sixteen studies with measurements of 10 nerves covering a total of 5149 nerves measured in 823 healthy children (445 boys and 378 girls) were included. Mean nerve CSA increased with age in the median nerve at the middle and lower third of the upper arm, mid-forearm, and distal wrist crease, the ulnar nerve at the middle third of the upper arm and elbow, the radial nerve at the spiral groove, and the tibial nerve at the popliteal fossa. Growth charts for nerve CSA for different age groups were developed.

DISCUSSION

This meta-analysis provides robust reference values for nerve CSA at different sites in children, and this can inform clinical practice and assist in identifying nerve enlargement. Moreover, it identifies the strength and quality of the current published data. We recommend future studies divide their samples into smaller age subgroups and standardize the anatomic site of measurement.

Correlation of age and the diameter of the cervical nerve roots C5 and C6 during the first 2 years of life analyzed by high-resolution ultrasound imaging

AIM

To analyze the increase in diameter of the nerve roots C5 and C6 in early childhood.

METHODS

The nerve roots of 56 children aged 0 days to 10 years (47 younger than 2 years) were examined by high-resolution ultrasound imaging. The correlation of diameter and age was statistically tested and a logarithmic regression analysis was performed to develop a logarithmic growth model.

RESULTS

The increase in nerve root diameter is greatest during the first 2 years of life and then the growth rate decreases steadily. The relationship between age and diameter follows a logarithmic curve (p < 10^-8 ).

INTERPRETATION

The main increase in the diameter of the nerve roots happens in the first 2 years of life. Comparing data from a previous study, our data also suggest that the maturation of the proximal part of the median nerve is comparable to the maturation of its distal segments. This suggests a synchronous maturation of the axons and myelin sheath for the whole extent of the nerve, from the radix to its very distal part.

WHAT THIS PAPER ADDS

Normative values for the size of the cervical nerve roots C5 and C6; an insight into the maturation of the proximal parts of the peripheral nervous system; and the correlation between age and cervical root diameter.

Newborn and elderly skin: two fragile skins at higher risk of pressure injury

Skin is a key organ maintaining internal homeostasis by performing many functions such as water loss prevention, body temperature regulation and protection from noxious substance absorption, microorganism intrusion and physical trauma. Skin ageing has been well studied and it is well known that physiological changes in the elderly result in higher skin fragility favouring the onset of skin diseases. For example, prolonged and/or high-intensity pressure may suppress local blood flow more easily, disturbing cell metabolism and inducing pressure injury (PI) formation. Pressure injuries (PIs) represent a significant problem worldwide and their prevalence remains too high. A higher PI prevalence is correlated with an elderly population. Newborn skin evolution has been less studied, but some data also report a higher PI prevalence in this population compared to older children, and several authors also consider this skin as physiologically fragile. In this review, we compare the characteristics of newborn and elderly skin in order to determine common features that may explain their fragility, especially regarding PI risk. We show that, despite differences in appearance, they share many common features leading to higher fragility to shear and pressure forces, not only at the structural level but also at the cellular and molecular level and in terms of physiology. Both newborn and elderly skin have: (i) a thinner epidermis; (ii) a thinner dermis containing a less-resistant collagen network, a higher collagen III:collagen I ratio and less elastin; (iii) a flatter dermal-epidermal junction (DEJ) with lower anchoring systems; and (iv) a thinner hypodermis, resulting in lower mechanical resistance to skin damage when pressure or shear forces are applied. At the molecular level, reduced expression of transforming growth factor β (TGFβ) and its receptor TGFβ receptor II (TβRII) is involved in the decreased production and/or increased degradation of various dermal extracellular matrix (ECM) components. Epidermal fragility also involves a higher skin pH which decreases the activity of key enzymes inducing ceramide deficiency and reduced barrier protection. This seems to be correlated with higher PI prevalence in some situations. Some data also suggest that stratum corneum (SC) dryness, which may disturb cell metabolism, also increases the risk of PI formation. Besides this structural fragility, several skin functions are also less efficient. Low applied pressures induce skin vessel vasodilation via a mechanism called pressure-induced vasodilation (PIV). Individuals lacking a normal PIV response show an early decrease in cutaneous blood flow in response to the application of very low pressures, reflecting vascular fragility of the skin that increases the risk of ulceration. Due to changes in endothelial function, skin PIV ability decreases during skin ageing, putting it at higher risk of PI formation. In newborns, some data lead us to hypothesize that the nitric oxide (NO) pathway is not fully functional at birth, which may partly explain the higher risk of PI formation in newborns. In the elderly, a lower PIV ability results from impaired functionality of skin innervation, in particular that of C-fibres which are involved in both touch and pain sensation and the PIV mechanism. In newborns, skin sensitivity differs from adults due to nerve system immaturity, but the role of this in PIV remains to be determined.

Quantifying the Elasticity Properties of the Median Nerve during the Upper Limb Neurodynamic Test 1

Background

The upper limb neurodynamic test 1 (ULNT1) consists of a series of movements that are thought to detect an increase in neuromechanical sensitivity. In vivo, no trail was made to quantify the association between the nerve elasticity and different limb postures during ULNT1.

Objectives

(1) To investigate the relationship between nerve elasticity and limb postures during ULNT1 and (2) to investigate the intra- and interoperator reliabilities of shear wave elastography (SWE) in quantifying the elasticity of median nerve.

Methods

Twenty healthy subjects (mean age: 19.9 ± 1.4 years old) participated in this study. The median nerve was imaged during elbow extension in the following postures: (1) with neutral posture, (2) with wrist extension (WE), (3) with contralateral cervical flexion (CCF), and (4) with both WE and CCF. The intra- and interoperator reliabilities measured by two operators at NP and CCF+WE and intraclass correlation coefficients (ICCs) were calculated.

Results

The intraoperator (ICC = 0.72–0.75) and interoperator (ICC = 0.89–0.94) reliabilities for measuring the elasticity of the median nerve ranged from good to excellent. The mean shear modulus of the median nerve increased by 53.68% from NP to WE+CCF.

Conclusion

SWE is a reliable tool to quantify the elasticity of the median nerve. There was acute modulation in the elasticity of the median nerve during the ULNT1 when healthy participants reported substantial discomfort. Further studies need to focus on the elasticity properties of the median nerve in patients with peripheral neuropathic pain.

Etiology of Carpal Tunnel Syndrome in a Large Cohort of Children

(1) Background: Carpal tunnel syndrome (CTS), a compressive mononeuropathy of the median nerve at the wrist, is rare in childhood and occurs most frequently due to secondary causes. (2) Methods: Medical history, electrodiagnostic findings, and imaging data of patients with CTS from two pediatric neuromuscular centers were analyzed retrospectively. The etiology of CTS was investigated and compared with the literature. (3) Results: We report on a cohort of 38 CTS patients (n = 22 females, n = 29 bilateral, mean age at diagnosis 9.8 years). Electrodiagnostic studies of all patients revealed slowing of the antidromic sensory or orthodromic mixed nerve conduction velocities across the carpal tunnel or lack of the sensory nerve action potential and/or prolonged distal motor latencies. Median nerve ultrasound was diagnostic for CTS and confirmed tumorous and vascular malformations. Etiology was secondary in most patients (n = 29; 76%), and mucopolysaccharidosis was the most frequent underlying condition (n = 14; 37%). Idiopathic CTS was rare in this pediatric cohort (n = 9; 24%). (4) Conclusion: Since CTS in childhood is predominantly caused by an underlying disorder, a thorough evaluation and search for a causative condition is recommended in this age group.