Botulinum Toxin Treatment for Thoracic Outlet Syndrome Induced by Subclavius Muscle Hypertrophy

Francesco Cavallieri,Valentina Fioravanti,Elisa Menozzi,Stefano Galletti,Franco Valzania,Sara Contardi

doi:10.3390/neurosci2020009

Abstract

Thoracic outlet syndrome (TOS) is frequently caused by bone abnormalities and congenital or acquired soft-tissue alterations. Among these, isolated Subclavius Muscle (SM) hypertrophy represents a rare condition that could lead to a reduction in costoclavicular space and brachial plexus compression. A 47-year-old forest ranger with a history of gun shooting during animal hunting and training sessions of skeet shooting for 20 years developed TOS due to ultrasonography-detected isolated SM hypertrophy, successfully treated with an ultrasound-guided Botulinum Toxin (BTX)-A injection. In our patient, ultrasonography of the brachial plexus has allowed SM hypertrophy to be recognized and to perform BTX-A injection just in the muscle, with a complete resolution of the symptoms.

Highlights

Thoracic outlet syndrome (TOS) represents a complex entity due to compression of the brachial neurovascular bundle at three different anatomical compartments represented by the medial interscalene triangle, the lateral subcoracoid space, and the intermediate costoclavicular space [1,2]
We report a case of TOS due to isolated hypertrophy of Subclavius muscle (SM) successfully treated with an ultrasound-guided Botulinum Toxin (BTX)-A injection
The contemporary implication of medial antebrachial cutaneous (MABC) sensory nerve action potential (SNAP) and median compound muscle action potential (CMAP) associated with a neurogenic pattern on needle EMG in abductor pollicis brevis (APB) represents the most common neurophysiological pattern in true neurogenic TOS [10]

Summary

Introduction

Thoracic outlet syndrome (TOS) represents a complex entity due to compression of the brachial neurovascular bundle at three different anatomical compartments represented by the medial interscalene triangle, the lateral subcoracoid space (or retropectoralis minor space), and the intermediate costoclavicular space [1,2]. Congenital abnormalities in the neck and thoracic outlet predispose a large part of the general population to develop neurovascular symptoms of the upper extremities. These anomalies remain symptomatically dormient until some activity causes muscle hypertrophy as a result of occupational arm position, athletic activities, or trauma [5]. We report a case of TOS due to isolated hypertrophy of SM successfully treated with an ultrasound-guided BTX-A injection

Case Report

Findings

Discussion

Conclusions