Utilization of Sonography Compared With Magnetic Resonance Imaging in Determining the Cross-Sectional Area of the Median Nerve in a Sample of Working Macaca fascicularis

Abstract

A preclinical study of 15 Macaca fascicularis monkeys was conducted to determine (1) the ability of detecting median mononeuropathy (MMN) within the median nerve after a work intervention and (2) the relationship between the layers of the median nerve during an acute inflammatory process by using sonography in conjunction with magnetic resonance imaging (MRI). Cross-sectional areas (CSAs) were imaged using MRI and sonography proximal to the carpal tunnel inlet (defined by the most distal portion of the radius) and further distal into the carpal tunnel (defined by the most proximal portion of the pisiform) at the prework exposure stage. CSAs measured on the outer edge of the median nerve were obtained from both modalities, at both anatomical locations. An intermodality t test demonstrated no statistical differences between the two sets of measurements (radius, P ≤ .15; pisiform, P ≤ .46). At the postwork exposure stage, sonographic measurements were obtained on the outer and inner borders of the median nerve at both anatomical levels. A two-tailed t test showed statistically significant differences within the carpal tunnel comparing pre- and postwork CSA measurements (radius, P ≤ .01; pisiform, P ≤ .297). The epineurial layer area was then determined as the difference between outer-border and inner-border CSAs. Pearson correlations between the epineurial layer and overall median nerve CSA within the carpal tunnel demonstrated a strong positive correlation that was statistically significant ( r = 0.97; P ≤ .01) after postwork exposure. Possible factors contributing to this acute phase of MMN could be hyperemia within the layers of the nerve and the development of Renault bodies. This work would need to be translated to human studies for further confirmation of the anatomic and clinical significance of this effect.

Use of Contrast‐Enhanced Sonography to Investigate Intraneural Vascularity in a Cohort of Macaca fascicularis With Suspected Median Mononeuropathy

“…Enhancing the visualization and measurement of vascularity will have an important translational impact on distinguishing the behavior of vascularity within the normal nerve to document inflammation associated with median mononeuropathy. The use of kinetics coupled with our work on the cross-sectional area of the layers of the nerve 21 may increase the sensitivity for the stages of development of median mononeuropathy. Together, documenting the inflammation process and identifying median mononeuropathy staging have the potential to lead to the development of specific biomarkers for early identification of median mononeuropathy in the acute stages before diagnosis as advanced carpal tunnel syndrome.…”

Longitudinal Analysis of Median Nerve Perfusion Using Spectral Doppler in a Working Animal Model

“…4 To determine if compression was taking place due to the inflammation of the median nerve throughout the MMN disease progression, transverse gray-scale images were also acquired to evaluate the cross-sectional area of the median nerve longitudinally. 2 Weekly quality control measurements were performed with the transducer and a tissue mimicking phantom throughout the study to monitor and document the reliability and reproducibility of equipment performance.…”

“…Carpal tunnel syndrome affects slightly less than 5 million people in the working population of the United States, with approximately 849 000 new cases reported each year in this country alone. [1][2][3] This musculoskeletal (MSK) disorder is characterized by compression of the median nerve as it passes through the carpal tunnel in the distal forearm. The carpal tunnel, defined by the area surrounded by the anatomical boundaries of the transverse carpal ligament superiorly and the first row of carpal bones inferiorly, provides space for the median nerve to travel distally for innervation of parts of the hand and digits.…”