En bloc resection of an anterior tumor (C1 to C7)

En bloc resection of a primary tumor is a significant undertaking, even in the most experienced hands. We therefore recommend referring these cases to quaternary centers with experience in primary spine tumor surgery.

Terminology is essential in primary tumor management.

An en bloc resection refers to a surgical attempt to remove a tumor in one piece without violating it.

On the other hand, an intralesional resection or a curettage refers to a deliberate intralesional resection.

An en bloc resection needs to be associated with a pathological margin description to be correctly defined.

Four types of margins are described:

• Intralesional – resection margin is within tumoral tissue
• Marginal – resection margin is within a reactional zone or pseudocapsule (in the spine, the epidural margin is often marginal)
• Wide – resection margin is within normal tissue
• Radical – this is extracompartmental resection and, as such, does not apply to spine tumors

Three conditions need to be met for an en bloc resection to be deemed possible.

• If we consider the spinal canal as a ring, there needs to be enough circumference of that ring to be removed piecemeal to allow delivery of the neural element.
• Access to the nerve root sleeve at its dural origin is required. This might only be achievable after mobilization.
• In the cervical spine, one vertebral artery needs to remain patent. Preoperative assessment of cerebral vasculature is useful to determine dominance and assess for patency of the posterior communicating artery.

If these conditions are not met, an en bloc resection will not be possible without a planned transgression of the tumor.

In this illustration, the spinal canal is circumferentially surrounded by a tumor. There is not enough uninvolved portion of the ring to allow an en bloc resection.

Proper planning is instrumental in the management of primary spine tumors. A multidisciplinary approach may be required depending on the localization of the tumor.

• Suspected primary spine tumors: essential initial assessment

This image shows a left-sided C3 Chordoma. 

Embolization procedures are recommended to reduce operative blood loss in hypervascular tumors, especially during more extensive resections.

Embolization should be considered for hypervascular tumors, such as giant cell tumors, aneurysmal bone cysts, and hemangiomas.

The role of the embolization is:

• To reduce the vascularity of the tumor
• To facilitate dissection around the tumor
• Mapping of spinal cord vascular supply and vertebral artery anatomy

Embolization on its own may also have a therapeutic effect.

This image shows the embolization of a hypervascular tumor.

A posterior approach followed by an anterior approach is generally recommended for a cervical tumor involving the vertebral body.

During the posterior approach, the uninvolved part of the spinal ring will be resected in a piecemeal fashion, and osteotomies and soft tissue dissections will be performed.

A wide visualization is essential in these cases, and a laminectomy involving one level above and below the tumor is recommended.

The goal is to achieve:

• Good visualization of normal and abnormal anatomy
• Safe decompression of the neural elements

Appropriate posterior tumor mobilization allows the tumor to be delivered during the anterior approach.

En bloc resection is a destabilizing procedure. As such, long constructs are required.

As a general rule, three vertebrae above and below the tumor are included in the construct. In multilevel tumors, or when there is poor bone quality, this construct can be extended.

As the procedure is often curative, it is important to verify that the spine is reconstructed in good alignment, and a solid bony union should be attempted.

Anterior reconstruction of the disc space or vertebral body following a complete corpectomy should be performed using a cage and plate.

Alternatively, an expandable cage or PMMA can be used.

Every case is unique.

To illustrate the surgical principle of an en bloc resection with posterior release and anterior delivery in the cervical spine, we will use a C5 tumor located in segments 4–9 of the WBB classification. The ipsilateral vertebral artery is involved.

The patient is placed prone.

• Prone position for approaches to C0–C7

A posterior midline approach to the cervical spine is performed.

• Posterior access to the cervical spine (C3–C7)

A wider dissection will typically be performed for primary tumors compared to a trauma case.

Careful analysis of the preoperative imaging is important to avoid tumor violation during the approach.

The incision may need a cranial extension when the tumor involves the upper cervical spine.

• Posterior access to the occipitocervical spine (C0–C2)

The incision may need a caudal extension when the tumor involves the lower cervical spine.

• Posterior access to the cervicothoracic junction (C7–T2)

Insert all screws according to the preoperative plan.

If C1 instrumentation is indicated, lateral mass screws are used.

• C1 lateral mass screw insertion

For C2 fixation, the following options are available (in order of preference):

• C2 pedicle screw insertion
• C2 pars screw insertion
• C2 laminar screw insertion

Consideration is given to using pedicle or laminar screws when doing an occiput to C2 fusion, as the starting point for pars screws often compromises the facet joint.

Fixation can be achieved with either lateral mass screws, pedicle screws, or a combination of the two.

Because lateral mass fixation is generally sufficient and carries less risk, pedicle screw fixation is limited to rare cases where lateral mass fixation would be insufficient or is not possible. A pedicle screw is most often used in C7 if instrumented.

• Lateral mass screw insertion (Magerl technique)
• Pedicle screw insertion in the cervical spine

Every effort should be made to contour the rod to decrease the risk of induced sagittal or coronal malalignment.

Contour the rod to align it with the lordosis achieved during positioning.

Extending instrumentation to the occiput may be necessary when the tumor involves the higher cervical spine.

• Instrumentation for occipitocervical fixation

Extending instrumentation to the thoracic spine may be necessary when the tumor involves the lower cervical spine.

• Pedicle screw insertion (T1–T3)

Perform a laminectomy according to the preoperative plan.

Dissection should progress from normal to abnormal tissues to protect normal neurological elements and facilitate dissection.

On the ipsilateral side, remove the inferior facet of C4 and the superior facet of C6 to isolate the C5 lateral mass.

Ligate the vertebral artery above and below the tumor.

The vertebral artery will have been embolized preoperatively to decrease the risk of bleeding and to facilitate its dissection.

Alternatively, the vertebral artery can also be taken from the anterior approach.

The C5 nerve root is ligated.

• Ligation of nerves

Posterolateral dissection is carried out as anteriorly as possible, staying outside the tumor in the normal muscular plane.

A sagittal osteotomy is initiated medial to the vertebral foramen from the C4/C5 to the C5/C6 disc.

This is done by working rostrally and caudally to the nerve root.

This sagittal osteotomy will be completed through the anterior approach.

Identify the C4/C5 and the C5/C6 discs and perform an epidural dissection outside the tumor pseudocapsule.

Transect the PLL at the level of the C4/C5 and the C5/C6 discs.

The transected PLL will be delivered together with the tumor through the anterior approach.

The posterior part of the tumor release is now completed.

To facilitate anterior dissection, gauze paddies may be left in the dissected plane.

Similarly, a Penrose is left in the anterior epidural space.

Insert the rods into the screw heads and secure them by tightening the inner nuts.

Excise the facet capsule and denude/curette the joint surface cartilage surfaces and the posterior cortex.

Insert pieces of bone graft (autograft, allograft) into the decorticated facet joint for fusion.

Perform a multilayer closure as described in the approach.

For patients undergoing tumor surgery and/or with a history of radiation:

• Plastic surgery should perform soft-tissue reconstruction to decrease the risk of wound complications
• Intrawound vancomycin can be applied to decrease the risk of postoperative wound complications

The patient is turned and placed in a supine position.

• Supine position for approaches to C3–C7

An anterior cervical approach is performed.

• Anterior access to the cervical spine (C3–C7)

For large tumors, a longitudinal cervical incision is preferred.

For large tumors or tumors that extend higher than the cervical spine, the assistance of a head and neck surgeon is desirable.

Develop the dissection plane towards the involved side until the dissection plane developed from the posterior approach is encountered.

Complete the C5 sagittal osteotomy that was initiated from the posterior approach using a high-speed burr or a bone scalpel.

Perform anterior cervical discectomies at the C4/C5 and the C5/C6 levels.

• Cervical discectomy

Once all soft tissue is released, the tumor is delivered.

The Penrose and the gauze paddies left during the posterior approach are removed.

The resection defect is measured using calipers.

Multiple anterior reconstruction options are available. These include:

• A mesh cage
• An expandable cage (PEEK or Titanium)
• A strut graft

Here, we will describe the technique using a mesh cage.

A mesh cage of the largest possible diameter is cut to the appropriate length.

En bloc resection is typically curative. As such, a solid bony union should be the goal, and the cage should be filled with grafting material to achieve this.

The cage is inserted and tapped into its final position under lateral fluoroscopic monitoring.

The Caspar pins are then removed.

When choosing the plate length, care must be taken to prevent it from damaging the mobile discs above and below.

Ideally, the plate will extend as little as possible above and below the endplates of the tumor level.

The plate is bent to accommodate the patient’s lordosis and fixed in place with two temporary pins placed in holes diagonal to each other.

The appropriate positioning of the plate is verified in AP and lateral views.

Variable angle plates with locking screws are also an option if necessary.

Malrotation of the plate is commonly seen on the AP view and can be addressed by temporarily removing one pin while adjusting the rotation.

Based on a preoperative measurement of vertebral body depth, screw holes are prepared with the appropriate depth. This is performed under lateral fluoroscopic guidance.

Screws of appropriate length are selected and applied but are not fully tightened until all screws have been inserted.

Final hardware positioning is verified in lateral and AP view.

Before wound closure, intraoperative imaging is performed to check the adequacy of reduction, position, and length of screws, and the overall coronal and sagittal spinal alignment.

Note the coils above and below in the sacrificed vertebral artery.

Lateral view of the above case

The wound is closed in a multilayer fashion, as described in the approach.

For patients undergoing tumor surgery and/or with a history of radiation:

• Plastic surgery should perform soft-tissue reconstruction to decrease the risk of wound complications
• Intrawound vancomycin can be applied to decrease the risk of postoperative wound complications

Patients are made to sit up in bed on the first day after surgery. Patients with intact neurological status are made to stand and walk on the first day after surgery.

Patients can be discharged when medically stable or sent to a rehabilitation center if further care is necessary.

Throughout the hospital stay, adequate caloric intake of a high-quality diet should be monitored.

Patients are generally followed with periodical x-rays at 6 weeks, 3 months, 6 months, and 1 year to monitor for hardware failure and with an MRI every 6 months for tumor surveillance.

Some primary benign tumors of the spine can recur years after surgery, and long-term tumor surveillance is important.