Ultrasound Is Superior to Magnetic Resonance Imaging for Detecting Peripheral Nerve Pathology in Mononeuropathies and Brachial Plexopathies (P06.149)

Abstract

Objective: Compare accuracy of magnetic resonance imaging (MRI) and ultrasound (US) in detecting peripheral nerve pathology. Background It is unknown whether MRI or US is superior for detecting peripheral nerve pathology. Design/Methods: We reviewed charts of 141 cases referred for neuromuscular US between 6/2007 and 10/2011 for suspected upper and lower extremity mononeuropathy(ies) or brachial plexopathy, excluding idiopathic carpal tunnel syndrome and ulnar neuropathy at the elbow, and identified cases who underwent MRI of the same limb for the same indication as the US. Imaging results were compared to the gold standard of surgical or, if unavailable, clinical/electrodiagnostic evaluation. Results: We identified 52 cases evaluated with both MRI and US. Focal nerve pathology was established in 46 and excluded in six by surgical (39) or clinical/electrodiagnostic evaluation (13). Diagnoses included peripheral nerve sheath tumors (18), traumatic (10) or idiopathic (8) neuropathy, fibrosis (4), compression by ganglion/synovial cysts (4) or other soft-tissue structures (3), non-nerve soft tissue tumor (3), intraneural granuloma (1) and vasculitis (1). US was more sensitive than MRI (93 vs. 70%) and equally specific (both 83%). Pathology accurately identified on US but not MRI included nerve enlargement (7), peripheral nerve sheath tumor (3), compression by anomalous muscle (1), and a hemangioma identified as non-nerve pathology on US but not MRI. Of these 12 cases with inaccurate MRI but not US, eight (67%) had lesions larger than two centimeters; only two lesions were outside the field of view of the MRI. In three cases classified as accurate for a single lesion on both MRI and US, US identified 11 additional lesions (multifocal neurofibromas, nerve enlargements, and fibrous thickening) not seen on MRI. Conclusions: Ultrasound is more sensitive, has equivalent specificity, and may better identify multifocal lesions than MRI in suspected mononeuropathies and brachial plexopathies. Supported by: This publication was made possible in part by the Washington University Neuromuscular Research Fund and the Grant Number UL1RR024992 from the NIH-National Center for Research Resources (NCRR), a component of the National Institutes of Health (NIH), and NIH Roadmap for Medical Research. Its contents are solely the responsibility of the authors and do not necessarily represent the official view of NCRR or NIH. Disclosure: Dr. Zaidman has nothing to disclose. Dr. Seelig has nothing to disclose.