Source: Jpn J Clin Hematol  |  Posted 5 years ago

By Crystal Phend

SAN DIEGO, C.A. -- February 28, 2006 -- Ultrasound imaging may make diagnosing thoracic outlet syndrome less expensive, faster and readily available, according to a presentation here at the annual meeting of the American Academy of Pain Medicine (AAPM).

In a presentation on February 25[^]th[], Sheldon E. Jordan, MD, FAAN, Clinical Associate Professor of Neurology, University of California, Los Angeles, California, United States, discussed the use of ultrasound to diagnose TOS.

The syndrome, which causes numbness and pain in the hand and forearm due to compression in the interscalene triangle, has been a subject of controversy. Like lumbar disc damage, anatomical findings of thoracic outlet syndrome are common in undiagnosed individuals and are not always associated with pain, which makes imaging based diagnosis more difficult.

Dr. Jordan presented an evaluation protocol combining clinical signs, imaging studies and a nerve block test.

Ultrasound imaging is a major component of the diagnosis protocol. Diagnostic ultrasound imaging refresh rates are high, allowing for dynamic imaging. It is also easy to measure nerve volume and bowing in the images, Dr. Webster said.

However, he highlighted that there is a very steep learning curve for interpreting and targeting the images. He strongly recommended using simultaneous electromyogram (EMG) monitoring to detect needle tip placement since it is hard to do with ultrasound imaging.

The protocol also calls for ultrasound of median, ulnar nerves, plexus, and the subclavian artery as well as an ultrasound- and EMG-guided scalene test block, which consists of single blinded provocative testing and anesthetic blocking of the nerves to the scalene, subclavius and pectoralis minor muscles.

A magnetic resonance imaging (MRI) test of the cervical spine may help in diagnosis, Dr. Jordan said.

Clinical diagnosis should include a history of typical thoracic outlet syndrome symptoms, an examination using positioning techniques to provoke the patient's pain and pulse obliteration, Tinel's sign over the brachial plexus, and exclusion of other conditions that can mimic some features of thoracic outlet syndrome such as fibromyalgia and complex regional pain syndrome.

Using this combination of tests for thoracic outlet syndrome results in cost savings by avoiding EMG, nerve conduction velocity, somatosensory evoked potential testing, MRI or computed tomography of the plexus.

An entire screening can be done in the course of a scalene test block in only about 5 minutes, he said.

"This is short, cheap and readily available," Dr. Webster said.

[Presentation title: New Advanced Imaging Techniques in the Diagnosis of Pain Syndromes: Advances in the Diagnosis and Treatment of Thoracic Outlet and Cervical Brachial Pain Syndromes. Update Session 402]