Surgical Approaches to the Cervicothoracic Junction

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Chapter 191 Surgical Approaches to the Cervicothoracic Junction

Surgical treatment of spinal disorders at the cervicothoracic junction is challenging because of the complex anatomy and biomechanical properties of this region. Access to the cervicothoracic junction is complicated by important vascular, visceral, and soft-tissue structures, and knowledge of these structures and surgical landmarks is essential for decompression and stabilization.

Cervicothoracic pathologies are relatively uncommon but include bacterial and tuberculous infections, fractures from primary bone disease, primary bone tumors, meningeal tumors, vascular malformations, congenital connective tissue and skeletal disorders, trauma, and thoracic disc herniations (Table 191-1). Up to 15% of patients with spinal neoplasms have lesions of the upper thoracic vertebrae, and 10% of spinal metastases arise from the T1 to the T4 region.1 One group reported that 8% of patients undergoing tumor resection required posterior instrumentation at the cervicothoracic junction.2 Additionally, as many as 9% of traumatic injuries can involve the cervicothoracic junction.3

TABLE 191-1 Differential Diagnosis of Lesions of the Cervicothoracic Junction

Metastatic tumors
Primary tumors of bone
Primary lymphoma
Intradural, extramedullar tumors
Intradural, intramedullary tumors
Bacterial infections
Tuberculous infections
Vascular malformations
Pathologic fracture (primary metabolic disease of bone)
Connective tissue and skeletal disorders
Traumatic vertebral fractures
Disc herniations

Up to 80% of unstable cervicothoracic pathologies can have neurologic compromise, and many of these lesions require surgical treatment. Unfortunately, injuries to this area are often overlooked on routine radiographic studies.4,5 The surgical goals include neural decompression, immediate stabilization, restoration of anatomic spinal alignment, and early rehabilitation. Appropriate treatment is necessary because acute unstable lesions of the cervicothoracic junction can have severe consequences including poor rates of recovery and significant mortality from cardiopulmonary-related complications.6

Posterior approaches, such as laminectomy and pediculectomy, are common approaches to many diseases of the spine. When treating anterior spinal element diseases, these techniques might not be adequate, can have a higher complication rate, and can disrupt spinal stability.7,8 For these reasons, a variety of anterior and posterolateral surgical approaches have been developed.

The first detailed description of a posterolateral approach to the anterior elements was the costotransversectomy.9 Although this technique gave adequate exposure of the middle and lower thoracic spine, it was less useful in the upper thoracic region. In 1954, Capener10 described a more-extensive posterolateral exposure, the lateral rhachotomy. In 1976, Larson and colleagues11 reported a modification of the lateral rhachotomy, the lateral extracavitary approach, which provided improved exposure of the middle and lower thoracic spine with less morbidity. However, these new additions were still limited at the cervicothoracic junction owing to the shoulder girdle. The lateral parascapular extrapleural operation, a modification of the lateral extracavitary approach, eliminates those obstructions and provides exposure of the thoracic vertebrae up to the inferior end plate of C7.12

Purely anterior, supraclavicular approaches to the cervicothoracic junction were initially described by Jonnesco13 and Brunig14 in 1923 and later used by Royle15 for spastic paralysis, by Gask16 for Raynaud’s disease, and by Ochsner and DeBakey17 for thoracic sympathectomy. However, exposure of the thoracic area was restricted by the clavicle, so the transmanubrial and transclavicular approach was developed by Sundaresan and colleagues18 in 1984 and modified by Birch and colleagues19 in 1990.

Another approach to the anterior thoracic vertebral elements, the anterolateral thoracotomy, was first described by Hodgson and colleagues.20 This approach involves resection of the third rib and requires transpleural mobilization of the lung with ligation and division of the intercostal arteries, intercostal veins, and the hemiazygos vein.

The following sections discuss the clinical features of cervicothoracic junction diseases, including preoperative evaluation, anesthetic considerations, relevant regional surgical anatomy, biomechanics of the cervicothoracic junction, surgical approaches, and options for surgical reconstruction and stabilization.

Clinical Features

The differential diagnosis for cervicothoracic pathologies is listed in Table 191-1. Disease processes in this region can manifest as pain without neurologic deficit, thoracic myelopathy, C7 or T1 radiculopathy, or a combination of these signs and symptoms. Table 191-2 lists the presenting findings in our series of patients with pathologic processes of the cervicothoracic junction (C7 to T4).1 Of these patients, 93% had decreased sensation, 83% presented with generalized upper thoracic back pain, and 58% had leg weakness. C7 and T1 lesions were less common, and consequently, 33% of patients presented with radicular symptoms and 35% demonstrated hand weakness on examination. Other, less common findings included ataxia (25%) and bowel or bladder dysfunction (17%).

TABLE 191-2 Signs and Symptoms at Presentation of Patients with C7-T4 Pathologic Processes (17 Patients)

Signs and Symptoms Percentage of Patients with Signs or Symptoms
Back pain 83
Radicular pain 33
Leg weakness 58
Decreased sensation 92
Hand weakness 35
Bowel or bladder dysfunction 17
Ataxia 25
Babinski sign 58

Preoperative Evaluation

Radiographic Evaluation

Radiologic evaluation begins with anteroposterior and lateral plain radiographs, and evidence of pathology includes malalignment, vertebral collapse, and widening of the pedicles. These radiographs can demonstrate traumatic or pathologic vertebral fractures, infections, tumors, and deformities.

Infections such as osteomyelitis or discitis have a variety of characteristics on plain radiographs. The earliest and most consistent finding of infection is narrowing of the disc space, which is present in 74% of patients.21 After 3 to 6 weeks, destructive changes in the body can be noted, which usually begin as lytic areas in the anterior aspect of the body adjacent to the disc and end plate. Active bone formation and sclerosis is also present in 11% of patients.

Metastatic disease of the bone has several classic signs including unilateral erosion of a pedicle, fishmouthing (cephalad and caudad end plate concavity within the vertebral body), osteoblastic changes, and vertebral body collapse. These findings can occur late in the disease process because 30% to 70% of the bone must be destroyed before changes are visible on plain radiographs.22

Radionucleotide bone scintigraphy is a sensitive but not specific method for detecting metastatic disease and infections.23,24 However, false negatives have been reported with lung cancer, renal cell carcinoma, myeloproliferative diseases, and regional ischemia, and in patients with leukopenia.2527

Myelography is primarily used to evaluate the patency of the subarachnoid space. Thus, myelography can demonstrate the level of a metastatic lesion by indentation or complete blockage of the myelographic dye column as it flows through the spinal canal. Additionally, myelography can demonstrate the presence of intradural extramedullary or intramedullary tumors, disc herniations, retropulsed vertebral fragments from pathologic or traumatic fractures, and vascular malformations.

Computed tomography (CT) also aids in the evaluation of diseases of the thoracic spine. These pathologies include metastatic disease, intradural tumors, disc herniations, and vascular malformations. Additionally, CT aids in defining the extent of paraspinal soft-tissue involvement for tumor staging and surgical planning, and also helps determine the extent of bone destruction. In addition, CT scans can help distinguish between osteoporosis and tumor as a cause of vertebral body collapse.

Magnetic resonance imaging (MRI) is the most important diagnostic tool for evaluating diseases of the thoracic spine. MRI permits early diagnosis of infection and recognition of paravertebral or intraspinal abscesses without the risk associated with myelography.28 MRI is also effective in demonstrating the extent of metastatic disease, primary tumors of bone, primary lymphoma, intradural tumors, thoracic disc herniations, and vertebral fractures. Additionally, this modality may be helpful in spinal vascular malformations, and when assessing metastatic disease, MRI has been found to be at least as sensitive and accurate as gallium and bone scanning combined.29 Finally, MRI provides anatomic detail, especially of soft tissue and nervous structures, not available with any other imaging studies.

Approach-Related Surgical Anatomy

Lateral Parascapular Extrapleural Approach and Anterolateral Thoracotomy Approach

The lateral parascapular extrapleural approach is a posterolateral surgery that allows nearly lateral access to the cervicothoracic junction vertebral bodies. The anterolateral thoracotomy is a transthoracic approach through the third rib that allows access to the anterior and lateral aspects of the vertebrae and for control of the mediastinal vasculature. The relevant anatomy may be summarized in three major areas: scapula and parascapular anatomy, posterior thoracic cage, and retromediastinal space and spinal anatomy.

Scapular and Parascapular Anatomy

Posterolateral access to the thoracic cage and vertebral elements is hindered by the scapular and the parascapular shoulder musculature (Fig. 191-1). Mobilization of the scapula anterolaterally is necessary and requires the disruption of the posteromedial shoulder musculature.

The first muscle encountered after skin incision is the trapezius muscle, which inserts medially at the superior nuchal line and external occipital protuberance and at the spinous processes of C1 through T12. This muscle extends laterally as the upper, intermediate, and lower divisions to the lateral third of the clavicle, the acromion, and the scapular spine. The trapezius muscle stabilizes and abducts the shoulder by the insertion of the lower fiber aponeurosis to the tubercle of the lower lip of the scapular spine. The trapezius muscle is innervated by the ventral rami of C3 and C4 of the spinal accessory nerve, which lies deep to the trapezius muscle and superficial to the levator scapulae. The arterial supply is from branches of the dorsal scapular artery.

The rhomboid major, rhomboid minor, and levator scapulae muscles are deep to the trapezius muscle. The ligamentum nuchae of the spinous processes provides the insertion site for the rhomboid major (T1 to T4) and the rhomboid minor (C6 to C7). Similarly, both of these muscles insert along the vertebral edge of the scapula: the rhomboid minor above and the rhomboid major below the scapular spine. The dorsal scapular artery supplies all three muscles, and the dorsal scapular nerve innervates the rhomboids. The levator scapulae muscle is innervated via branches from C3, C4, and C5. Both the artery and nerve lie deep to the muscle bodies, are located medially under the scapula, and are rarely seen during a routine exposure. The serratus posterior superior muscle lies deep to the trapezius muscle from C6 through T2, and the splenius arises ventral to this muscle at the ligamentum nuchae and upper thoracic spine, dividing into the splenius capitis and splenius cervicis. The splenius capitis inserts on the superior nuchal line and mastoid process, and the splenius cervicis joins the levator scapulae to insert on the transverse processes of C1 through C4. These muscles stabilize and rotate the skull.

During exposure of the cervicothoracic junction, the spinous process insertions of the trapezius, rhomboid, serratus posterior superior, splenius capitis, and splenius cervicis are laterally retracted as a single group. As these muscles are taken down, the scapula can be rotated anterolaterally out of the operative field. This maneuver exposes the posterior and posterolateral rib cage.

Posterior Thoracic Cage

The deep or intrinsic muscles including the erector spinae and transversospinalis muscles are next encountered (Fig. 191-2). The erector spinae muscles originate from the sacrum as a dense aponeurotic band and divide into three columns below the last rib as they proceed superiorly. The iliocostalis muscle is located laterally and inserts from the angles of the ribs and into the cervical transverse processes from C4 through C6 as series of related muscular bundles. Each bundle extends over approximately six segments, with the more medial bundles extending more cephalad.

The longissimus muscles (thoracis, cervicis, and capitis) insert into the lumbar and thoracic transverse processes and ribs between T2 and T12. Medially, the muscle bundles extend from T1 through T4 to the transverse processes of C2 through C6. Medial to the cervical insertions, other bundles extend superiorly to the mastoid process deep to the splenius capitis and sternocleidomastoid muscles. Thus, the longissimus is the only erector spinae muscle to reach the skull. Finally, the aponeurotic spinalis muscle extends from the upper lumbar to the lower cervical spinous processes.

The transversospinalis muscle group passes cephalad from the transverse processes to the spinous processes immediately deep to the erector spinae muscles in three layers. The most superficial layer, the semispinalis, arises from the tips of the transverse processes and inserts at the tips of the spinous processes approximately five vertebral levels cephalad. At the cervicothoracic junction, this muscle is primarily composed of the semispinalis capitis. This muscle passes from the upper thoracic transverse processes and lower cervical articular processes (C4 to T4) to the occipital bone between the superior and inferior nuchal lines. The muscle fibers run vertically and attach to the ligamentum nuchae. The intermediate layer, the multifidus, originates from the erector spinae aponeurosis and from the transverse processes up to C4 and extends to the lower border of each spinous process. This muscle spans approximately three levels. The deepest muscles of this group, the rotatores, are muscles that bridge one interspace. They pass from one transverse process root to the spinous process root immediately above.

These muscle groups extend the vertebral column or can bend and rotate the vertebrae. The erector spinae and transversospinalis muscles are typically dissected off the spinous processes, laminae, facets, and transverse processes as a single muscular mass. This dissection exposes all the vertebral elements from the spinous processes to the transverse processes, as well as the costotransverse ligaments, joints, and ribs.

Each rib articulates with its own vertebral body and transverse process, the vertebra above, and the intervertebral disc between them (Fig. 191-3), but the first rib articulates only with its own vertebral body. Each of these articulations forms separate synovial joints, and the joints of the posterolateral vertebral body surface are separated by an intra-articular ligament that attaches to the intervertebral disc. An articular capsule surrounds the joints and attaches to the vertebral body anteriorly via the radiate ligament.

The costotransverse joint is surrounded by an articular capsule and is strengthened laterally by the lateral costotransverse ligament and the costotransverse ligament. The superior costotransverse ligament joins the neck of the rib to the transverse process immediately above. The canal formed between this ligament and the vertebral column contains the dorsal ramus of the spinal nerve and the dorsal branch of the intercostal artery. Finally, the ribs are attached to one another through the intercostal musculature, which originates medially on the superior rib and inserts laterally on the inferior rib.

The intercostal musculature contains the intercostal nerve, artery, and vein as they pass between the internal intercostal membrane and the pleura and between the internal and innermost intercostal muscles. Most commonly, the intercostal vein is cephalad and the intercostal artery is more caudad. The intercostal nerve may be separate from these structures and is located most caudad. The pleura lies ventral to the intercostal bundle and the intercostal muscles.

Retromediastinal Space and Spinal Anatomy

By dissecting away the pleura, the lateral vertebral elements are exposed. The neural foramen follows the intercostal bundle medially and contains the dorsal root ganglion, as well as the gray and white rami communicantes, which course ventrally to the sympathetic chain and ganglia. The sympathetic chain is within a fascial compartment formed by the fusion of the mediastinal and prevertebral fascia over the costovertebral articulation.

The first two intercostal spaces are supplied by branches of the costocervical trunk from the highest intercostal artery. This artery descends anteriorly along the necks of the first two ribs to the ventral rami of the eighth cervical and first thoracic nerves. The remaining intercostal arteries arise from the posterior surface of the thoracic aorta. The first four of these arteries ascend to the third through six intercostal spaces and become the intercostal arteries. Each intercostal artery runs obliquely across the vertebral body from caudad to cephalad with the periosteum. These arteries are located deep to the azygos or hemiazygos vein, the thoracic duct, and the sympathetic trunk.

The major portion of the first thoracic ventral ramus passes cephalad across the neck of the first rib to join the eighth cervical nerve in the brachial plexus. A small intercostal branch runs across the inferior surface of the first rib and enters the first interspace close to the costal cartilage. The ventral ramus of the second thoracic nerve can also send a branch to the brachial plexus. If this branch is large, the lateral cutaneous branch of the second intercostal nerve is small or absent. Although the intercostal nerves below T1 can usually be ligated to facilitate exposure, C7 and T1 cannot be sacrificed without causing significant hand dysfunction.

Transmanubrial Approach

The transmanubrial approach is an anterior approach that allows direct access to the vertebral bodies and associated pathologies. This approach consists of three major steps: the thoracic inlet, the visceral and vascular compartments of the superior mediastinum, and the retromediastinal space.

Vascular and Visceral Compartments of the Superior Mediastinum

The visceral compartment is contained within the visceral fascia and consists of the trachea, esophagus, and thyroid gland. The neurovascular compartment is surrounded by the carotid sheath and contains the carotid arterial system, internal jugular vein, and vagus nerve. These compartments create a potential space, the viscerocarotid space, which extends from the base of the skull to C7–T4. The inferior extent of this space depends on the location of fusion between the visceral and alar fascia.

In the upper thorax, the visceral compartment continues down to the bronchi, where the fascia fuses with the visceral and parietal pleurae. Between the visceral and parietal pleurae exists a potential intrapleural space. The carotid sheath extends inferiorly to the subclavian vessels, where it fuses into the axillary sheath. In the superior mediastinum, the vascular compartment is defined by multiple surrounding fascial layers. These fasciae include the transthoracic fascia ventrally, the prevertebral fascial extension dorsally, visceral fascia caudally, the parietal pleurae laterally, and the pericardium inferiorly.

The venous structures consist of the brachiocephalic veins and branches. These veins descend from the neck into the superior mediastinum just posterior to the thymus gland or its remnants. The right brachiocephalic vein is formed posterior to the medial end of the right clavicle and descends vertically into the superior mediastinum. The left brachiocephalic vein is formed posterior to the medial end of the left clavicle and descends diagonally to join the right brachiocephalic vein posterior to the right first costal cartilage. These veins become the superior vena cava. Tributaries draining into the brachiocephalic veins include the vertebral and first posterior intercostal veins in the neck and the internal thoracic, thymic, and inferior thyroid veins in the superior mediastinum. On the left, the superior intercostal vein (which drains the second and third intercostal spaces) also joins the left brachiocephalic vein.

The arterial structures consist of the aortic arch, brachiocephalic artery, left common carotid artery, and left subclavian arteries and their branches. The aortic arch initially ascends posterior to the superior vena cava, then turns inferiorly as it passes anterior and to the left of the vertebral column. A second concave turn occurs as the arch curves around the anterolateral visceral compartment to reach the vertebral column.

The brachiocephalic artery is the first branch off of the aortic arch. This artery ascends vertically and to the right, dividing into the right common carotid and subclavian arteries posterior to the right sternoclavicular joint. The second aortic branch, the left common carotid artery, ascends vertically into the carotid sheath. The left subclavian artery is the third branch, and this artery ascends superiorly and to the left, curving around the thoracic inlet and into the axillary sheath. Neither of these arteries branch in the superior mediastinum.

As previously described, the carotid sheath contains the carotid arterial system, the internal jugular vein, and vagus nerve, and the visceral fascia contains the esophagus and trachea. Between these two adjacent compartments lies the viscerocarotid space. Blunt dissection of this space exposes the alar fascia and the retropharyngeal space. In the superior mediastinum, the left brachiocephalic vein runs obliquely and superiorly from left to right. Caudally, the operative field is limited by the aortic arch and its branches at the T3 and T4 vertebrae. Additionally, the right recurrent laryngeal nerve and the lymphatics terminating in the thoracic duct can cross the retropharyngeal and retromediastinal space between C7 and T3. The left recurrent laryngeal nerve branches off the vagus in the superior mediastinum, loops around the ligamentum arteriosum, and ascends within the visceral fascia between the esophagus and trachea.

In the superior mediastinum, the thoracic duct runs dorsal and to the left of the esophagus between the visceral and alar fascia. The duct ascends to the C7 level, where it lies laterally and dorsally to the carotid sheath. It then courses caudally and ventrally to the branches of the thyrocervical trunk and phrenic nerve, terminating at the junction of the left internal jugular and subclavian veins. A right lymphatic trunk follows a similar course to the thoracic duct.