9: Occipital-Cervical Fusion

Published on 21/04/2015 by admin

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Last modified 21/04/2015

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Procedure 9 Occipital-Cervical Fusion

Howard B. Levene, John Christos Styliaras, Alexander R. Vaccaro, Jack I. Jallo, James S. Harrop

Indications

image This procedure is typically performed to treat instability of the occipital-cervical joint—specifically, to ensure stability and protect the neurologic structures, prevent deformity, and reduce or eliminate pain. The presence of occipital-cervical instability increases the risk for compression or trauma to the spinal cord/brainstem by means of pathologic translation, longitudinal displacement, or basilar invagination. The consequences include pain, cranial nerve palsies, respiratory distress, paresis, paralysis, and even sudden death.

image There are two basic presentations of occipital-cervical instability:

• Acute occipital-cervical instability—usually precipitated by trauma (Figure 9-1, A and B). Traumatic causes of such instability have a high rate of amelioration of pain symptoms following surgical intervention using the screw/rod construct.
• Chronic occipital-cervical instability—with causes ranging from degenerative processes to inflammatory/autoimmune, infectious, neoplastic (metastatic or primary), or even congenital in origin (Figure 9-2, A and B).
image

FIGURE 9-1, A-B

image

FIGURE 9-2, A-B

Indications Pitfalls

• Reducible versus nonreducible (e.g., whether traction will be necessary)

• Surgical versus external immobilization/fusion

• Occipital-cervical fusion versus atlantooccipital fusion (e.g., C1 lateral mass fusion, odontoid screw)

Techniques Controversies

• A successful occipital-cervical fusion can provide a favorable outcome in most types of occipital-cervical instability, whether acute or chronic. There are a variety of techniques to obtain a fusion varying from onlay grafts, wiring, plates, and most recent plate/rod constructs. The screw/rod constructs have been shown to provide improved neurologic status postoperatively, decreased instrumentation failure rates, and few postoperative complications.

• However, in patients with neoplasms, posterior wiring and rods have the highest rate of arthrodesis, while screw/rod constructs are associated with a significantly less favorable rate of arthrodesis.

• Still, in patients suffering from inflammatory/autoimmune diseases, screw/rod constructs provide the best outcomes, especially when compared with posterior wiring and inlay in situ bone grafting, which provides poor results postoperatively. Similar results are found in cases of traumatic occipital-cervical instability.

• Need for halo preoperatively

• Need for halo postoperatively

Examination/Imaging

image Anteroposterior (AP) and lateral spine radiographs

image Cervical spine computed tomography (CT) scan with sagittal and coronal reconstructions

image Measurement of reference lines, such as Chamberlain line (posterior of the hard palate to the dorsum of the foramen magnum) and the Wackenheim line (extending the course of the clivus), are of somewhat limited value.

image Obtain magnetic resonance imaging (MRI) of the cervical spine (especially with myelopathy) to determine degree and severity of spinal cord compression (Figure 9-3).

image Obtain a myelogram (CT and radiographic) if MRI is not available or is contraindicated (i.e., when the patient has a pacemaker or other MRI-incompatible hardware). Although a myelogram can directly visualize the spinal cord, it also provides valuable information on the degree of compression, or lack of, on the spinal cord.

image

FIGURE 9-3

Treatment Options

• External fixation (halo) only

• Combined approach (anterior resection of dens, posterior fusion)

• Various occipital-cervical fusion devices (bone and wire, loop and wire, screw and rods, in-out option for occipital screw)

Surgical Anatomy

image Occiput/inion (Figure 9-4)

image Vertebral arteries (Figure 9-5)

image Condyle joints and C1 and C2 bony anatomy (C2 screw placement)

image Lateral masses (C3-6 lateral mass screw placement) (Figure 9-6, A and B)

image

FIGURE 9-4

image

FIGURE 9-5

image

FIGURE 9-6, A-B

Positioning

image Place patient in prone position in three-point pin fixation.

image Alternatively, the patient can be placed in prone position in a halo ring affixed to the table.

image Another option is continuous traction.

Positioning Pearls

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