CPT® Code 21705

The procedure described by CPT® Code 21705 involves the surgical division of the scalenus anticus muscle, which may be accompanied by the resection of a cervical rib. This intervention is primarily aimed at treating conditions such as thoracic outlet syndrome and cervical rib syndrome. Thoracic outlet syndrome is characterized by the compression of the brachial plexus, a network of nerves that innervates the arm, which can occur due to the tightness of the scalenus anticus muscle. In some cases, a supernumerary cervical rib, which is an additional rib that arises from the seventh cervical vertebra, can also contribute to this compression. The procedure typically begins with an incision made above the clavicle to access the surgical site. The sternocleidomastoid muscle is then exposed and incised to facilitate access to the scalenus anticus muscle. During the surgery, the scalenus anticus muscle is divided, and any fibrous bands that may be compressing the brachial plexus are also excised. If a cervical rib is present and is determined to be contributing to the compression of the brachial plexus, the surgeon will proceed to resect this rib. It is important to note that CPT® Code 21700 should be used when only the division of the scalenus anticus muscle is performed, while CPT® Code 21705 is specifically designated for cases where both the division of the muscle and the resection of the cervical rib are conducted.