Management of Upper Cervical Spine Tumors

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Chapter 19 Management of Upper Cervical Spine Tumors

INTRODUCTION

Spinal tumors around the atlantoaxial spine are very rare, and most of them are metastatic. Patients with tumors in this area present with severe mechanical neck pain that is elicited in flexion, extension, and lateral rotation. Pain on lateral rotation distinguishes atlantoaxial tumors from tumors occurring in the subaxial cervical spine. In the subaxial spine, mechanical pain generally is a late manifestation indicating a compression or burst fracture with resultant instability.1 Neurological symptoms resulting from a tumor at C1 and C2 are rare. Patients with C2 nerve root involvement or compression may present with occipital neuralgia. Cranial nerve involvement suggests a tumor extension to the skull base. Myelopathy is rare, given the wide mid-sagittal canal diameter at this spine level. Most cases of spinal cord compression at this level result from pathological fracture subluxations rather than an epidural tumor.

Patients with normal spine alignment or minimally displaced fractures can be treated with radiation therapy and immobilization in a hard collar, and those with marked displacement are treated with surgery. Osteolytic destruction of multiple atlantoaxial spine elements results in pathological fractures, which are somewhat different from the patterns of traumatic fractures. However, instability, defined in the trauma literature by degree of displacement and angulation, may be applicable. Patients are considered to have significant subluxations resulting in instability if they have odontoid displacement that is more than 5 mm or angulation that exceeds 11 degrees with displacement of more than 3.5 mm. As with tumors of the subaxial spine, atlantoaxial tumors generally involve the anterior spine elements (i.e., odontoid and body of C2). Although recent studies advocate aggressive anterior resection and stabilization for atlantoaxial tumors, posterior instrumentation without anterior resection can result in immediate stabilization, deformity reduction, and neurological preservation.

TOTAL SPONDYLECTOMY FOR UPPER CERVICAL TUMORS (TUMOR MASS ON C2–4 LEVELS)

POSTERIOR APPROACH

After the airway is maintained with a tracheostomy, the patient is positioned prone with skeletal fixation. A midline skin incision is made, and subperiosteal muscle dissection is accomplished from the external occipital protuberance to the upper thoracic levels to expose the multiple level laminae and facet joints (Fig. 19-1). Complete bilateral laminectomies and facetectomies of C2–4 are performed with wide exposure of the exiting nerve roots.

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Fig. 19-1 Posterior decompression from C2 to C4.

Modified from Jackson RJ, Gokaslan ZL: Occipitocervicothoracic fixation for spinal instability in patients with neoplastic processes J Neurosurg 1999;91[1 suppl]:81–89.

Using a high-speed drill with a diamond burr, the vertebral artery (VA) is freed from C2 to C4 on both sides. When the facetectomy is complete, the cut surface of the pedicle is exposed (Fig. 19-2). The pedicle forms the posteromedial wall of the transverse foramen. Continuous drilling of the pedicle can open the transverse foramen. During drilling, the exiting nerve root on the upper level may be injured. The exiting nerve root is located on the upper portion of the exposed pedicle (see Fig. 19-2). If the VA on the unilateral side is encased within the tumor mass, the cephalad and caudal portions out of the tumor mass are exposed.3 An initial dissection plane is created around the lateral aspect of the tumor.

For the easier dissection, the C2 and C3 nerve roots may be sacrificed without significant functional loss. If necessary, the C4 root also can be included. A Silastic sheet is then placed between the tumor and the ventral dura to protect the neural structures during the subsequent anterior procedure. Occipitocervical fixation is performed using the contoured titanium rods.4

ANTERIOR PROCEDURE—TRANSMANDIBULAR, CIRCUMGLOSSAL, RETROPHARYNGEAL APPROACH

The patient is positioned supine with the neck in extension. The anterior neck dissection can be made via either side, and transmandibular, circumglossal, retropharyngeal exposure is performed.

Upper Neck Dissection

A curvilinear incision is begun below the mastoid tip and extended 2 cm inferior and parallel to the lower margin of the mandible inferiorly and medially to the mentum. The incision continues to the vertical incision to the midline of the lower lip. The turning point of the incision lies on the hyoid bone. The lower lip is incised with a zigzag incision. A mucosal incision is made at the alveolar margin under the lower lip. After the skin incision, a vertical incision of platysma is made on the mental symphysis to the superior notch of the thyroid cartilage (Fig. 19-3, A). The platysma can then be transected across its fibers parallel to the direction of the primary incision for the full length of the exposure. Subplatysmal flaps are elevated to expose the upper neck, the submandibular gland, and surrounding tissue.

A supraomohyoid neck dissection (usually by an otolaryngologist) provides access to the lingual and hypoglossal nerves as well as the internal carotid artery (ICA), external carotid artery, and internal jugular vein.5 The sternocleidomastoid muscle is retracted laterally to expose the carotid sheath. The digastric muscle is then divided, and the mylohyoid muscle is freed from the hyoid bone and the geniohyoid from the mandible. The hypoglossal nerve should be identified and saved.

Mandibulotomy

A stairstep mandibulotomy is performed between tooth 24 and 25 (lower two mandible molars).6 The mandible is exposed by subperiosteal dissection laterally to the mental foramen. For accurate alignment, the mini-plates should be pre-bent and fitted, and screw holes should be predrilled. Only then is the mandible split with a staircase osteotomy.

Dissection follows the floor of the mouth posteriorly toward the glossopharyngeal sulcus, which allows the mandible to swing laterally and the tongue medially (Fig. 19-3, B). An incision is made from the midline under the tongue where the mandible has been divided and is continued around the tongue to the tonsillar pillar. The tongue is retracted away from the field as the mandible half is swung out laterally with the cervical myocutaneous flap. The oropharynx and the upper cervical pharyngeal space communicate. The styloid process is palpated and the muscular attachments are separated. The ICA, internal jugular vein, and the 9th, 10th, 11th, and 12th cranial nerves are identified superiorly to the skull base.

As the incision approaches the anterior tonsillar pillar, it splits into two limbs. The upper limb of incision extends to the soft palate. This incision is then carried onto the hard palate approximately 1 cm medial to the alveolar ridge. It then passes anteriorly around to the contralateral hard palate. The lower limb of the incision extends into the hypopharynx, passing lateral to the tonsil and the orifice of the eustachian tube. The levator and tensor veli palatini muscles and the eustachian tube are transected, and a retropharyngeal dissection is used to elevate the pharynx off of the longus colli muscles and expose the clivus and upper cervical spine (Fig. 19-3, C). This pharyngeal flap is elevated and rotated medially. The longus capitis muscle and the prevertebral fascia cover the clivus and upper cervical spine. The posterior pharyngeal wall is incised, and the longus capitis and rectus capitis muscles are retracted (Fig. 19-3, D).

CASE ILLUSTRATION

CASE II

This patient was diagnosed with a C2 metastasis of breast cancer (Fig. 19-8). X-rays and magnetic resonance imaging (MRI) show that the odontoid subluxation is less than 2 mm. The spinal cord is not compressed. The patient responded to external beam radiation therapy in a hard collar and showed significant pain resolution. She was then weaned from the collar 6 weeks after treatment.

CASE IV

This patient presented with posterior neck pain with occipital pain. Preoperative lateral x-rays showed that the C2 posterior element completely disappeared and that the C3 posterior element was partially eroded (Fig. 19-14). With a dynamic lateral view, anterior column instability was not shown (Fig. 19-15). The operation was performed using the posterior approach only. A C2 total laminectomy and bilateral facetectomy were performed. At the C3 level bilateral laminae were removed but the facets remained. Occipitocervical stabilization was performed with a screw-rod system (Fig. 19-16). The lateral mass screws were inserted at the C3–6 levels.

VERTEBRAL ARTERY MANAGEMENT DURING TUMOR REMOVAL

The management of VAs in cases of cervical spine tumor can be performed in several ways. They may be dissected and mobilized away from the tumor; they may be ligated and resected with the tumor; or in certain cases they may be resected and reconstructed with a venous interposition graft.7 The VA from C6 to C2 (V2 segment) may be reached from an anterolateral approach behind the carotid sheath.8 At C2 and C1 (V3 segment) the artery is approached laterally. In the V2 and V3 segments it is completely surrounded by a continuous periosteal sheath and venous plexus. The key points in VA control are to stay outside the periosteal sheath as long as possible and to obtain adequate VA control proximal and distal to the lesion.

C1–2 LEVEL (V3 SEGMENT)

Exposure of Vertebral Artery

After all the muscles are detached from the transverse processes of C1 and C2, then the accessory nerve, the VA, and the lateral part of C1 and C2 are visualized.9 The internal jugular vein is anterior to the transverse process, and the accessory nerve crosses it here after it emerges from the jugular foramen on the way to the SCM. The VA can be identified between C2 and C1 by following the inferior border of the inferior oblique muscle in the loose adipose tissue (see Fig. 19-20). The ventral ramus of the C2 nerve root crosses lateral to the VA from posterior to anterior. The transverse process of C1 is rongeured away, permitting the artery to be displaced out of C1 and reflected posteriorly, allowing clear access to the tumor in the anterior part of C1 and C2. The artery can be followed down into the C2 transverse foramen after dividing the ventral ramus of the C2 root (Fig. 19-21). The periosteal-venous sheath is opened and reveals significant venous bleeding. To control the bleeding, it is best to coagulate the vein and strip the sheath from the artery. In the V3 segment, the VA is surrounded by a venous plexus, and both the VA and its venous plexus are enclosed in a continuous periosteal sheath. This sheath is continuous with the periosteum of the transverse foramina of C1 and C2, with the deep aponeurosis of the muscles between these foramina, with the posterior atlantooccipital membrane that arches over the VA groove of the atlas, and with foramen magnum dura mater.

For resection of the C1 and C2 vertebral body mass, the approach is through the space between the internal jugular vein and the VA.

Vertebral Artery Transposition

For the transposition, complete control of the VA and cutting of all the branches are required.10 After controlling the two parts of the suboccipital segment on each side of the C1 transverse foramen, the periosteal sheath is followed inside the foramen, splitting the periosteum from the bone. Then the transverse foramen is unroofed, biting its external wall progressively using the Kerrison rongeur (Fig. 19-22). To achieve the transposition, the medial wall must also be resected to provide space in the concavity of the VA loop and allow the VA to be pulled without damaging the periosteal sheath.

BELOW C2 LEVEL (V2 SEGMENT)

Incision

The incision follows the anterior or posterior border of the SCM muscle. The upper end of the incision is taken across the attachment of the muscle at the mastoid muscle if it becomes necessary to divide this attachment.

The internal jugular vein is identified medial to the muscle, and the dissection is carried out between the carotid sheath and the SCM, down to the anterior tubercles of the cervical vertebrae.11 When the tumor mass encases the VA, the proximal segment to the mass needs to be controlled. If the intact anterior tubercle below the tumor mass is identified, the muscles are detached from the anterior tubercle (Fig. 19-23). The bone is gently rongeured down to the foramen transversarium. The VA is identified within the venous periosteal sheath. Then the venous sheath is opened and dissected circumferentially around the artery with bipolar coagulation. If only the proximal control is required, the naked portion of the VA should be exposed at the C7 level. Once the artery is exposed from the venous sheath, a rubber vessel loop is passed around it. When proceeding in the cephalad direction, great care should be taken to avoid injuries to nerve roots and phrenic nerve lying on the scalenus anterior muscle.

CASE ILLUSTRATION

CASE I

A 44-year-old man with a history of thyroid cancer presented with several weeks of neck pain. At examination he showed a decreased sensation to pain on the right face (V3 area). The patient was slightly hyperreflexic in the left upper extremity.

On preoperative MRIs a tumor mass was detected from the C3 body and extended to the anterior direction. The anterior mass invaded into the epidural space from C2 to C4, and the spinal cord was severely compressed (Fig. 19-24). The right VA was encased in the tumor mass at the C3 level (Fig. 19-25). A preoperative angiography was performed to evaluate the patency of the VA. During the angiography a balloon occlusion test was performed. Neurologically, no abnormal finding was detected. The VA was trapped with two balloons to control bleeding.

Via a posterior approach, the right C2–3 and C3–4 facets were removed with the tumor mass, and posterior stabilization was performed. On the right side, a C2 pedicle screw and a C5 lateral mass screw were purchased. On the left side, lateral mass screws were inserted on the C3–5 levels (Figs. 19-26 and 19-27). With a subsequent anterior approach, a C3 corpectomy and epidural mass removal were carried out. A vertebral body replacement cage was inserted into the corpectomy site and supplementary plating was done. On the postoperative x-ray, the embolic material is seen in the right VA.

References

1 Fourney DR, York JE, Cohen ZR, et al. Management of atlantoaxial metastases with posterior occipitocervical stabilization. J Neurosurg. 2003;98(2 suppl):165-170.

2 Bilsky MH, Shannon FJ, Sheppard S, et al. Diagnosis and management of a metastatic tumor in the atlantoaxial spine. Spine. 2002;27:1062-1069.

3 Rhines LD, Fourney DR, Siadati A, et al. En bloc resection of multilevel cervical chordoma with C-2 involvement. Case report and description of operative technique. J Neurosurg Spine. 2005;2:199-205.

4 Jackson RJ, Gokaslan ZL. Occipitocervicothoracic fixation for spinal instability in patients with neoplastic processes. J Neurosurg. 1999;91(1 suppl):81-89.

5 DeMonte F, Diaz EJr, Callender D, et al. Transmandibular, circumglossal, retropharyngeal approach for chordomas of the clivus and upper cervical spine. Technical note. Neurosurg Focus. 2001;10:E10.

6 Ryu SI, Kim DH. Surgical approaches to the craniovertebral junction. In: Kim DH, editor. Spinal Instrumentation: Surgical Techniques. New York: Thieme; 2005:3-13.

7 Sen C, Eisenberg M, Casden AM, Sundaresan N, Catalano PJ. Management of the vertebral artery in excision of extradural tumors of the cervical spine. Neurosurgery. 1995;36(1):106. Jan; 15 discussion 115–6

8 Shucart WA, Borden JA. Lateral approaches to the cervical spine. Menezes AH, Sonntag VKH, editors. Principles of Spinal Surgery, vol 2. New York: McGraw-Hill. 1996:1325-1331.

9 Choo WH, Lee MC, Kim DH. Posterior and far-lateral approaches to the craniovertebral junction. In: Kim DH, et al, editors. Surgical Anatomy and Techniques to the Spine. Philadelphia: Saunders; 2006:33-44.

10 Muhlbauer M, Knosp E. The lateral transfacetal retrovascular approach for an anteriorly located chordoma originating from the second cervical vertebra. Acta Neurochir (Wein). 2001;143:369-376.

11 George B, Zerah M, Lot G, et al. Oblique transcorporeal approach to anteriorly located lesions in the cervical spinal canal. Acta Neurochir (Wien). 1993;121:187-190.