Fascicular constrictions above elbow typify anterior interosseous nerve syndrome

Abstract

Introduction In this study we tested the hypothesis that fascicular constrictions (FCs) of the median nerve proximal to the elbow joint characterize anterior interosseous nerve syndrome (AINS). Methods Magnetic resonance neurography (MRN) and ultrasound (US) examinations were evaluated in 45 patients with clinically suspected AINS. All 22 patients at site 1 underwent MRN and 8 underwent US; all 23 patients at site 2 underwent US. Results Median nerve FCs were identified in all MRN cases; FCs and/or fascicular enlargements were identified in 88% of US cases. Most FCs were in the mediannerve posterior/posteromedial region and were proximal to the elbow joint line (mean distance: MRN, 5.4 cm; US, 7.5 cm), with the exception of a single FC (located 1 cm distal). No extrinsic compression of median or anterior interosseous nerves was identified in the arm or forearm. Discussion AINS is a noncompressive neuropathy characterized by median nerve FCs in the arm.

Parsonage-Turner Syndrome Following COVID-19 Vaccination: MR Neurography

“…Within the arm, 4 severe, hourglass-like constrictions and T2-weighted signal hyperintensity of the anteromedially positioned fascicular bundle of the median nerve were detected; this bundle represents the PT/FCR bundle based on the known topographical, fascicular arrangement of the median nerve ( Figure 1B-C ). 10 Repeat electromyography, consistent with imaging findings, demonstrated severe denervation and no motor unit recruitment within the PT or FCR muscles. Muscles in the anterior interosseous nerve distribution were normal on MRI and electromyography.…”

Imaging and treatment of phrenic nerve hourglass‐like constrictions in neuralgic amyotrophy

“…Epi-and peri-neurolysis of the HGC was performed ( Figure 1C). 1 Six months post-operatively, the patient reported improvement in dyspnea and fluoroscopic sniff testing confirmed active motion of the right hemidiaphragm.…”

“…3 When performed by radiologists specializing in nerve imaging, reductions in nerve caliber that suggest the presence of HGCs on ultrasound and MRI have been shown to correlate strongly with operative findings. [1][2][3] Furthermore, these constrictions may represent a therapeutic target, as microneurolysis of HGCs has shown promise in NA patients who fail to recover. 1 Historically, treatment for phrenic paralysis ranges from observation to respiratory therapy to mechanical ventilation.…”

“…[1][2][3] Furthermore, these constrictions may represent a therapeutic target, as microneurolysis of HGCs has shown promise in NA patients who fail to recover. 1 Historically, treatment for phrenic paralysis ranges from observation to respiratory therapy to mechanical ventilation. Partial improvement in respiratory symptoms is generally seen over 1 to 2 y in half of NA patients.…”

Trapped or twisted? Teasing out anterior interosseous neuropathy

“…Both high‐resolution nerve ultrasound (US) and dedicated MR neurography (MRN) have developed into powerful tools to tease out hitherto unknown aspects of different types of peripheral nerve disorders . In a retrospective case series published in this issue from two centers with extensive imaging experience in focal inflammatory neuropathies, Dr. Sneag and coworkers describe the imaging results of 45 patients with a clinical diagnosis of acute AIS. Twenty‐two patients from one center underwent MRN of the upper extremity, and 23 patients from second center underwent US of the median nerve, to localize the pathology and assess the pathophysiological mechanism of AIS.…”