Anterior Approaches to the Cervicothoracic Junction

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Chapter 20 Anterior Approaches to the Cervicothoracic Junction

Ung-Kyu Chang, Se-Hoon Kim, Daniel H. Kim

INTRODUCTION

The cervicothoracic junction is the vertebral region from C7 to T4, an area in which many pieces of critical vascular and visceral structures are encountered. Decompression of anterior lesions in the cervicothoracic junction is difficult in several viewpoints. The sternum blocks the surgical corridor and the operative field is deep because of thoracic kyphosis. The spinal canal is narrow, and the presence of great vessels acts as physical constraints.

A standard low cervical approach often can expose to the T1 level in most patients. In patients with long necks, it is possible to expose down to T2 with a standard low cervical approach. However, for usual anterior exposure of T2–4, more extensile approaches, such as the transmanubrial or trans-sternal approaches, will be necessary.

TRANSCLAVICULAR–TRANSMANUBRIAL APPROACH

Radiological studies of the upper thoracic spine have indicated that at least the T3 vertebra can be visualized in the majority of patients in whom a suprasternal approach is undertaken after the splitting and mobilization of the manubrium.¹

The external landmarks for level identification are T2–3 at the suprasternal notch and T4–5 at the sternal angle (Fig. 20-1). Before adopting this approach, it is important preoperatively to confirm the extent of the lesion and the position of the upper margin of the sternum on lateral radiographs. It also is essential to assess the affected spinal cord level and its relation to the level of the upper margin of the sternal manubrium because this relationship varies among individuals.

Fig. 20-1 In this patient, the sternomanubrial junction corresponds to the T2–3 intervertebral disc level.

SKIN INCISION

Linear vertical incision starts from the anterior border of the ipsilateral sternocleidomastoid muscle and is continued down to below the sternal angle.

MUSCLE INCISION

The platysma muscle is divided in line with the skin incision. Deep cervical fascia is incised. The sternal and clavicular heads of the sternocleidomastoid muscle are divided and retracted laterally. The sternohyoid and sternothyroid muscles are detached below the level of the clavicle and retracted medially. A blunt dissection is performed between carotid sheath and tracheoesophageal complex.

BONE REMOVAL

The medial third of the clavicle and manubrium is dissected periosteally. The clavicle is divided at the junction of the medial and middle thirds (Fig. 20-2). All procedures are safe when the periosteum is separated from the bone by using a raspatory. While excising the sternum, the sternum lining is carefully separated using the raspatory to avoid possible damage to the internal mammary artery (Fig. 20-3).²

Fig. 20-2 Extent of bone removal in the transmanubrial approach. Most of the manubrium is removed with the medial one-third of the clavicle.

Fig. 20-3 The internal mammary arteries run along the sternum.

The separation procedure is extended caudally to expose the level of the lesion, such as the upper thoracic spine. It is important to approach the vertebral body of the lower cervical spine and then extend the operative field to the caudal side. In such a case, no direct surgical procedure for the aortic arch and the great vessels is necessary. At some levels of the operative field, these great vessels may have to be retracted to the right or left, but directly separating them is unnecessary.

The left side of the manubrium can be removed piecemeal along its posterior periosteum.

Alternatively, the manubrium and sternoclavicular joint can be left intact and reflected with the sternal head of the sternocleidomastoid muscle (Fig. 20-4).

Fig. 20-4 The manubrium and sternoclavicular joint are left intact and reflected with the sternal head of the sternocleidomastoid muscle.

VASCULAR DISSECTION

Dissection is carried deeper until the great vessels are identified. Inferior thyroid vessels can be ligated. If the cranial part, approximately 50% of the sternal manubrium, is removed, the surgeons do not need to retract the left innominate vein. A bilateral retraction of the brachiocephalic trunk can expose the T1 and T2 vertebral body (Fig. 20-5).

Fig. 20-5 Great vessels around the sternomanubrial junction.

VERTEBRAL BODY EXPOSURE

After the great vessels, esophagus, and trachea are retracted, the prevertebral fascia is exposed. The prevertebral fascia is identified and incised to expose the vertebral bodies. The angle of the vertebral body is deepened to the caudal side. The T1 vertebral body is a little shallow and the T3 vertebral body is deep. The disc plane is so inclined to the anterior side that the cephalad screw should be angled more than 45 degrees for suitable fixation. Reconstruction of the clavicle and manubrium is optional but can be accomplished with wire or plating systems.

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