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

Abstract

Carpal tunnel syndrome (CTS) is a form of median mononeuropathy (MMN) of the wrist that has become the most common nerve entrapment syndrome of the upper limbs. During the acute phase of CTS, the median nerve becomes hyperemic and enlarged as it begins to be compressed by the transverse carpal ligament; however, continual compression ultimately leads to median nerve ischemia. The objective of this study was to longitudinally quantify the amount of perfusion of the median nerve using spectral Doppler in a working animal model, as the cohort prospectively increased their risk of MMN through a repetitive pinching task. The results of the study provided low-level evidence that the use of spectral Doppler to accurately detect longitudinal changes in vascularity within the median nerve may be diagnostically inadequate. As the subjects in the study moved through the working and nonworking stages of study, spectral Doppler alone proved to lack the level of sensitivity needed to detect physiologic changes within the nerve. This outcome, although inconclusive when it comes to detecting changes in median nerve vascularity, does suggest the need for this method to be analyzed in conjunction with other sonographic features and provocative testing.

Detection of Intraneural Median Nerve Microvascularity Using Contrast‐Enhanced Sonography

“…Continued excursion of the compressed median nerve can result in microtrauma of the myelin sheath, as well as vascular disturbances, leading to increased nerve perfusion 4 – 9 . The nerve then becomes hyperemic, which characterizes the acute stage of carpal tunnel syndrome 5 – 7 . As median nerve compression continues and becomes chronic, ischemic processes begin, leading to more severe and often irreversible damage 10 .…”