Neurogenic thoracic outlet syndrome: current diagnostic criteria and advances in MRI diagnostics

Abstract

<jats:p>Neurogenic thoracic outlet syndrome (nTOS) is caused by compression of the brachial plexus as it traverses from the thoracic outlet to the axilla. Diagnosing nTOS can be difficult because of overlap with other complex pain and entrapment syndromes. An nTOS diagnosis is made based on patient history, physical exam, electrodiagnostic studies, and, more recently, interpretation of MR neurograms with tractography. Advances in high-resolution MRI and tractography can confirm an nTOS diagnosis and identify the location of nerve compression, allowing tailored surgical decompression. In this report, the authors review the current diagnostic criteria, present an update on advances in MRI, and provide case examples demonstrating how MR neurography (MRN) can aid in diagnosing nTOS. The authors conclude that improved high-resolution MRN and tractography are valuable tools for identifying the source of nerve compression in patients with nTOS and can augment current diagnostic modalities for this syndrome.</jats:p>

The thoracic outlet syndromes: Part 1. Overview of the thoracic outlet syndromes and review of true neurogenic thoracic outlet syndrome

“…This technique uses heavy T2 weighting, fat suppression, and pulsation artifact suppression to image peripheral nerves while simultaneously suppressing the surrounding tissue. Common MRN sequences include standard spin‐echo T1‐weighted images and fast spin‐echo T2‐weighted images with fat suppression, as well as short‐tau inversion recovery sequences (to provide intrinsic fat suppression) and a newer protocol, termed SPAIR (T2 spectral adiabatic inversion recovery), which enhances the signal‐to‐noise ratio and further suppresses fatty tissue . This technique, which generates nerve images referred to as neurograms, can demonstrate nerve fiber deviations, such as those resulting from fibrous bands.…”

New Diagnostic and Treatment Modalities for Neurogenic Thoracic Outlet Syndrome

“…Specifically, variations of MRN such as Short Tau Inversion Recovery (STIR) sequences and the Spectral Adiabatic Inversion Recovery (SPAIR) preparatory module deliver a more complete anatomical description of the nerves comprising the brachial plexus. Additionally, the use of diffusion tensor imaging sequences to visualize nerve fascicles is employed in the modeling technique of tractography, which allows for a more comprehensive assessment of peripheral nerve injury [9]. One study using MRN demonstrated a 100% positive predictive value in all thirty patients.…”

Choosing Surgery for Neurogenic TOS: The Roles of Physical Exam, Physical Therapy, and Imaging

“…The addition of diffusion tensor imaging (DTI) to standard MRN sequences may even permit visualization of individual nerve fascicles. Such techniques may permit direct imaging of nerve compression or impingement by bony, muscular, or fibrous structures [30]. In classic nTOS, MRN may be able to directly visualize anomalies of the lower brachial plexus cords, such as compression, flattening, or neural and peri-neural inflammation.…”