Surgical Approaches to the Cervicothoracic Junction

Chapter 191 Surgical Approaches to the Cervicothoracic Junction



Richard G. Fessler, Daniel H. Kim


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.25–27


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.



Metabolic Evaluation


Metabolic evaluation of cervicothoracic junction pathology should include complete blood count, kidney profile (electrolytes, blood urea nitrogen, and creatinine), liver profile, and erythrocyte sedimentation rate. Other helpful metabolic evaluations include calcium, phosphorus, alkaline phosphatase, serum protein electrophoresis, and serum transferrin analysis. Antinuclear antibody and rheumatoid factor analysis assist in the evaluation for rheumatoid arthritis. Additionally, bone marrow aspiration may be helpful in the diagnosis of blood-borne dyscrasias, and antigenic markers for specific tumors include carcinoembryonic antigen, serum acid phosphatase, and prostate-specific antigen.



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.


image

FIGURE 191-1 Relationship of the scapula to the incision, as well as the surgical approach to the cervicothoracic junction, via the lateral parascapular extrapleural approach.


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.


image

FIGURE 191-2 Cross-sectional anatomy of the deep or intrinsic muscle layer of the upper thoracic spine. M., muscle.


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.


image

FIGURE 191-3 Relationship of each rib and rib head with the transverse process, vertebral bodies, and intervertebral disc. Note that each rib articulates not only with its own transverse process and vertebral body but also with the vertebral body immediately above it. Ant., anterior; Lig., ligament; Sup., superior.


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.



Thoracic Inlet


The superior mediastinum is defined anteriorly by the manubrium, which lies 5 cm anterior to the vertebral bodies. The suprasternal notch corresponds to a T2–3 level, and the sternal angle lies at the T4–5 level. The sternohyoid, sternothyroid, and sternocleidomastoid muscles originate at the manubrium. The sternohyoid muscle runs from the dorsal manubrium to the ventrocaudal hyoid bone, with attachments to the sternoclavicular joint capsule, and the sternothyroid muscle attaches along the dorsal midline of the manubrium. These muscles are supplied by the ventral rami of C1 to C3 via the hypoglossal nerve and ansa cervicalis.


The sternocleidomastoid muscle arises from the mastoid process and superior nuchal line and attaches to the manubrioclavicular joint. This muscle is innervated by the accessory nerve and is supplied by branches from the superior thyroid artery. Careful fascial dissection enables safe removal of the manubrium and medial third of the clavicle without injury to the brachiocephalic or subclavian veins. This removal exposes the pleural apices and Sibson’s fascia, an extension of the transthoracic fascia.



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.



Retromediastinal Space


When the alar and mediastinal fascia are incised, the median compartment of the retromediastinal space is entered. The prevertebral fascia covers the vertebral bodies and envelops the longus colli muscles. Autonomic branches to the cardiopulmonary plexuses may be seen in this region and can be sacrificed if necessary.



Cervicothoracic Biomechanics


The cervicothoracic junction extends from C7 through T4 and includes the lower brachial plexus, the thoracic outlet, and the superior mediastinum. This region also has a narrow spinal canal and narrow pedicles, and it represents a transition from the lateral masses of the cervical vertebra to the transverse processes of the thoracic spine. The structures affecting spinal stability include the vertebral bodies and intervertebral discs, anterior and posterior longitudinal ligaments, and the interarticulating facet joints and ligamentous complex posteriorly.


The cervicothoracic junction is exposed to significant forces, particularly in flexion and distraction. The anterior elements are the primary structures that transfer compressive forces between the adjacent vertebral bodies. The posterior spinal components have little weight-bearing function but are important for the attachment of supporting ligaments and resistance to the extremes of motion. The anterior and posterior longitudinal ligaments prevent extreme flexion and extension, whereas the intertransverse and capsular ligaments inhibit lateral bending and axial rotation.


The rib cage and its sternal articulations also increase thoracic spine stability. Additionally, biomechanical studies have shown that the costotransverse joints and rib cage play a significant role in lateral bending and axial rotation.30 Berg31 describes the sternal rib complex as the fourth spinal column. At the cervicothoracic junction, disruption to any two spinal columns is unstable and should be treated accordingly.


Trauma, degenerative processes, infection, and neoplastic involvement can alter the biomechanical function of this area and can predispose the cervicothoracic junction to instability. The transition from the mobile, lordotic cervical spine to the rigid, kyphotic thoracic spine exposes this region to unique stress as the transfer of weight occurs between spinal columns.32,33 This stress is amplified by the decrease in vertebral index from C6 to T1.34


Cervicothoracic surgeries can destabilize the region, leading to kyphosis and spinal cord compression. Several authors have reported increasing spinal deformity caused by a previous cervicothoracic junction laminectomy.5,35,36 Spinal fusions ending at the cervicothoracic junction can also be a contributing factor to iatrogenic instability.37 In a series by Steinmetz and colleagues, factors that contributed to fusion failure included laminectomy without instrumentation, multilevel corpectomies, previous cervical surgery, smoking, and deformity correction.38 The increased incidence of neurologic injury may also be related to the smaller spinal canal size and tenuous blood supply.4,5


Few studies have addressed the biomechanics and stability of fixation at the cervicothoracic junction, and the majority of biomechanical studies in this region have focused on the cervical spine.39,40 Biomechanical tests on cervical cadaveric spines have shown superior stability of posterior screw fixation techniques as compared with anterior fixation.41,42 In addition, posterior wiring techniques were found to be inferior to the intact condition and performed poorly in movements other than flexion.41,43 In extension and torsion, lateral mass screws and plating devices provide increased stability relative to posterior wiring alone.44


Biomechanically, transpedicular screw fixation of the lower cervical spine provides the most stability to the unstable cervical segment. Rhee and colleagues demonstrated that C7 pedicle screws were superior to lateral mass screw and wiring techniques, and other studies have shown the importance of increasing screw length as measured by testing of in-line screw pullout strength.45–47 These findings must be weighed against a high rate of pedicle violation with pedicle screw placement in the lower cervical spine. 48 Rhee and colleagues also demonstrated that if C7 pedicle screws were not possible, then C6 and C7 lateral mass fixation was necessary to provide similar stability.47


Bueff and colleagues49 compared three different fixation devices at the cervicothoracic junction following a simulated C7–T1 distractive-flexion injury: an anterior plate, a posterior plate, and a posterior hook-and-rod system. This study showed that the hook-and-rod system provided as much as six times the stiffness of the intact spine, whereas the anterior plate provided stiffness similar to that of the intact condition. Clinically, standalone anterior fixation at the cervicothoracic junction can lead to a high failure rate.50


Vaccaro and colleagues51 examined the use of a novel plate-and-rod construct for the cervicothoracic junction and concluded that their device supported the maximal loading conditions of the native cervical spine. Kreshak and colleagues examined the mean stiffness of three different posterior cervicothoracic fixation systems after a two- or three-column injury.52 These systems included one plate-and-screw system and two rod-and-screw systems. Following a two-column injury, all three constructs were able to stabilize the cervicothoracic junction in flexion and extension, lateral bending, and axial rotation. After a three-column injury, all three systems failed to provide adequate stability, especially in extension. These results suggest that additional anterior stabilization may be needed when a three-column injury occurs at the cervicothoracic junction.


A biomechanical study by O’Brien and colleagues raised the possibility of posterior-only fixation to treat a three-column injury at the cervicothoracic junction. These investigators used two-level fixation above and below the level of injury, with the addition of two cross-linking connectors to their construct.42 It is worth noting that their injury model did not involve damage to the vertebral body. However, combined anterior and posterior instrumentation for three-column injuries was supported by the biomechnical work of Prybis and colleagues. These authors demonstrated instability with posterior-only constructs and significantly improved stability with the addition of anterior fixation with or without corpectomy.53 This study also showed a trend toward decreased flexibility with increasing levels of thoracic instrumentation.

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Jul 16, 2016 | Posted by in NEUROSURGERY | Comments Off on Surgical Approaches to the Cervicothoracic Junction

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