Ulnar Neuropathy at the Elbow: From Ultrasound Scanning to Treatment

Abstract

Ulnar neuropathy at the elbow (UNE) is commonly encountered in clinical practice. It results from either static or dynamic compression of the ulnar nerve. While the retroepicondylar groove and its surrounding structures are quite superficial, the use of ultrasound (US) imaging is associated with the following advantages: (1) an excellent spatial resolution allows a detailed morphological assessment of the ulnar nerve and adjacent structures, (2) dynamic imaging represents the gold standard for assessing the ulnar nerve stability in the retroepicondylar groove during flexion/extension, and (3) US guidance bears the capability of increasing the accuracy and safety of injections. This review aims to illustrate the ulnar nerve's detailed anatomy at the elbow using cadaveric images to understand better both static and dynamic imaging of the ulnar nerve around the elbow. Pathologies covering ulnar nerve instability, idiopathic cubital tunnel syndrome, space-occupying lesions (e.g., ganglion, heterotopic ossification, aberrant veins, and anconeus epitrochlearis muscle) are presented. Additionally, the authors also exemplify the scientific evidence from the literature supporting the proposition that US guidance is beneficial in injection therapy of UNE. The non-surgical management description covers activity modifications, splinting, neuromobilization/gliding exercise, and physical agents. In the operative treatment description, an emphasis is put on two commonly used approaches—in situ decompression and anterior transpositions.

Cross-Sectional Area Reference Values for Sonography of Peripheral Nerves in Taiwanese Adults

“…Additionally, NMUS improves the diagnostic yield in mononeuropathies by facilitating localization and aiding in the determination of the nature of the neuropathy (e.g., compression neuropathy vs. ganglion/cyst, tumor, or trauma) and in polyneuropathies (2,3) by aiding in the identification of inflammatory neuropathies and distinguishing between different hereditary neuropathies (4)(5)(6). NMUS is also used for the diagnosis and treatment of entrapment and traumatic neuropathies (7)(8)(9).…”

EURO-MUSCULUS/USPRM Dynamic Ultrasound Protocols for Elbow

“…1F). 29 Of note, it is paramount to avoid excessive pressure, that is, not to artificially "stabilize" the possibly snapping structures. In this sense, extra gel or gel pad can be adopted to minimize probe compression.…”

“…However, a shallow retroepicondylar groove can well predispose to ulnar nerve instability. 32,33 Chronic frictions related to the instability may lead to inflammation and edema of the neural tissue, that is, frictional/tractional painful neuritis 29 with or without a feeling of snapping during elbow movements. Importantly, dynamic US can be used during postoperative follow-up after (transposition) surgery as well (Video 13, http:// links.lww.com/PHM/B482).…”

“…Then, passive/active flexion and extension of the elbow can be performed to dynamically visualize how the ulnar nerve and the medial head of the triceps brachii muscle react to the joint motions (Fig. 1F) 29 . Of note, it is paramount to avoid excessive pressure, that is, not to artificially “stabilize” the possibly snapping structures.…”

Sonographic normal values for the cross-sectional area of the ulnar nerve: a systematic review and meta-analysis

“…Ultrasound is increasingly used in the diagnosis of neuropathies, including ulnar nerve entrapment, and importantly complementing electrodiagnostic studies. As point of care device, advantages of nerve ultrasound include low cost, practical non-invasive bedside testing, wide availability and flexible field of view [1]. It can provide essential diagnostic information on relevant morphological changes, such as precise anatomical site and exact nature [2][3][4].…”