The value of neuromuscular ultrasound in relation to clinical and electrophysiological testing in the diagnosis of thoracic outlet syndrome

Abstract

Background Thoracic outlet syndrome (TOS) diagnosis has long been challenging and controversial with no available golden standard diagnostic test. Objectives To assess the value of NMUS as a new diagnostic tool for TOS and compare it with other clinical and electrophysiological studies. Patients and Methods This study was conducted on 20 patients with clinical TOS and 10 healthy controls. They were subjected to history taking, clinical examination, provocative tests, functional assessment using shoulder pain and disability index, electrophysiological and imaging studies including x-ray and NMUS. Pectoralis minor muscle deformation and brachial plexus compression was detected using NMUS by measuring the pectoral bowing ratio (PBR), PBR is significant if >10% on provocation with arm abduction. Results In this case control study, mean age of 20 patients was 34.20±9.52. Female:male ratio was 13:7 without significant difference between patients and controls regarding age or sex. Mean pain and disability scores were 73±13.42 and 55.30±15.68 respectively. Compound medial antebrachial cutaneous (MAC) nerve conduction and F-wave studies was positive in 85% of patients and none of the controls. Similarly, NMUS positive finding was detected in 75% of patients and none of the controls with highly significant difference between two groups, P<0.01. Diagnostic accuracy (DA) of NMUS for TOS was 83.3% comparable to x-ray and compound MAC, F-wave studies (DA=93.3%, 90% respectively). Conclusion Neuromuscular ultrasonography is an important, painless, sensitive tool for assessment of TOS. It is complementary to other imaging and electrophysiological studies and their combination could help in objective diagnosis of TOS.

Keywords

• electrophysiological testing
• neuromuscular ultrasound
• thoracic outlet syndrome