Thoracic outlet syndrome is a collection of conditions that lead to the compression of the nerves and blood vessels in the thoracic outlet area. Symptoms such as pain, numbness, weakness, and discoloration may occur depending on the specific structures affected. There is currently no agreed-upon diagnostic criteria, but a detailed patient history, physical examination, and appropriate imaging tests can help with diagnosis. The first-line treatment for thoracic outlet syndrome usually involves conservative measures like physical therapy, lifestyle changes, medications such as NSAIDs and injections like botulinum toxin A, steroids, and local anesthetics. If conservative treatments fail, surgical decompression may be considered. This chapter aims to provide a review of the epidemiology, causes, anatomy, symptoms, diagnosis, and treatment of thoracic outlet syndrome.

Thoracic outlet syndrome (TOS) is a rare, often perplexing disorder caused by compression of neurovascular structures, just above the first rib and behind the clavicle or under the pectoralis minor, leading to cervicogenic–brachial pain and other symptoms in neck and upper limb. This chapter reviews the subtypes of TOS, such as neurogenic and vasogenic, illustrates the anatomy of the thoracic outlet and discusses the common sites of nerve entrapment.

Botulinum neurotoxin (BoNT) is an emerging treatment for TOS. Intramuscular injection of BoNT reduces muscle spasm and produces denervation atrophy of hypertrophied muscles, relieving compression of neurovascular structures and ameliorating both neurogenic and vasogenic symptoms. Risks associated with injection and the BoNT itself make guidance and targeting techniques important. Therefore, ultrasound (US) guidance for accurate injection placement is stressed. This chapter will briefly review TOS and the literature related to use of BoNT for TOS and also provide a detailed review of procedural techniques for US guidance.