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Surgical exposure of the anterior cervicothoracic junction poses a unique challenge for spine surgeons. Several distinct features of this region contribute to the difficulty of approach. First, major anatomic structures can impede surgical access. These structures include the contents of the carotid sheath, the thyroid gland, and osseous structures such as the sternum and clavicle. Furthermore, many of the contents of the thoracic inlet, including the esophagus, trachea, thoracic duct, and essential nerves (i.e., vagus, recurrent laryngeal, phrenic, and sympathetic), must also be safely negotiated during the approach. Finally, in cases of significant disease, anatomic boundaries can be poorly defined, thus contributing to increased difficulty with anterior approaches to the cervicothoracic junction.
The anterior cervical approach was originally described in the 1950s. However, given the complexities and aforementioned challenges of this region, subsequent modifications of this technique were later described. In particular, approaches to the cervicothoracic junction require specific attention. This chapter primarily focuses on two anterior cervicothoracic junction exposure techniques: the supraclavicular approach and the transmanubrial transclavicular approach.
Cervicothoracic Junction: Anatomic Considerations
The cervicothoracic junction can pose multiple challenges given the presence of numerous visceral and vascular structures and the location of this region as a transition zone between two regions of the spine. The cervical spine has a developmentally normal anatomic lordosis and is generally flexible. In contrast, the thoracic spine is kyphotic and generally rigid.
This region has many unique characteristics, such as the ratio of the spinal canal to spinal cord diameter. The spinal canal diameter is the narrowest at the cervicothoracic junction, but the spinal cord in this region is near its widest diameter. Thus, pathologic processes in this region can cause early compressive symptoms. Furthermore, the cervicothoracic junction is a vascular watershed zone. Cervical radicular branches provide blood supply to the lower subaxial cord, whereas thoracic radicular arteries from the aorta provide much of the blood to the spinal cord parenchyma at the level of the cervicothoracic junction (C6 to T2).
Another surgical challenge to the lower neck includes the soft tissue, which traverses vasculature and essential peripheral nerves. The anterolateral region of the neck contains the muscles of the hypopharynx and the carotid sheath (including the carotid artery, jugular vein, and vagus nerve). Deep and medial to the sternocleidomastoid (SCM) muscle are the esophagus and trachea. Ventral to the trachea are the thyroid and parathyroid glands. Injury to any of these vital structures can produce undesired morbidity and contribute to the challenges of the cervicothoracic junction.
Developing a bloodless plane is critical to the surgical approach. Thus, identification of the SCM muscle is critical. This muscle originates from the mastoid process and inserts at the sternum and the clavicle. Just medial and deep to this muscle are the midline structures: strap muscles, trachea, and esophagus. The strap muscles include the sternohyoid, sternothyroid, omohyoid, and thyrohyoid. Between the SCM and strap muscles are multiple neurovascular structures. The right recurrent laryngeal nerve branches from the vagus nerve and curves around the subclavian artery. The left recurrent laryngeal nerve curves underneath the aortic arch and runs superiorly between the trachea and the esophagus in the tracheoesophageal groove more caudally (and is often less aberrant). Other important structures in this region include the carotid artery, the vagus nerve, and the jugular vein. Within the superior mediastinum, the subclavian artery and vein, the brachiocephalic artery and vein, and the thoracic duct can all be encountered. The thoracic duct is medially bounded by the first thoracic vertebrae and the manubrium and laterally by the first ribs. The cupula of the lung lies just inferior to the thoracic duct.
Surgical Techniques
Supraclavicular Approach
The supraclavicular approach to the cervicothoracic junction provides excellent exposure without requiring disruption of the sternum or clavicle. Surgical exposure using this technique is perhaps the most familiar because it is essentially an oblique extension of the typical anteromedial approach. However, this technique can pose specific challenges. This technique is often extremely difficult in patients with short necks, prominent muscular development, or significant kyphosis. Furthermore, this approach can result in a deep operative field and may require an acute angle to place anterior instrumentation.
The authors traditionally use a transverse skin incision that is 2 cm above the clavicle and extends from the midline to the lateral border of the SCM. Like many surgeons, the authors employ a left-sided approach because of the more consistent course of the left recurrent laryngeal nerve. However, a right-sided approach can be used if attention is given to a potentially aberrant course of this nerve.
The initial operative steps are similar to those employed with a traditional anterior cervical approach. Following careful dissection of more superficial structures (including the platysma muscle), the first critical landmark is the SCM muscle. At the anterior border of this muscle, the superficial and deep cervical fascia should be dissected thoroughly, both cranially and caudally. The SCM can be isolated with finger dissection, and its attachment to the sternal and clavicular heads can be identified. Subsequently, the muscular attachments can be transected in a subperiosteal manner and reflected superiorly ( Fig. 5-1 ).
