9: Occipital-Cervical Fusion

Published on 21/04/2015 by admin

Filed under Surgery

Last modified 22/04/2025

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 1962 times

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

• It is crucial to evaluate the patient’s optimal head position, because with an occipital-cervical fusion, they will be locked in this position.

• The patient must adequately overhang the operating room table.

• The patient’s chest must be supported on gel rolls; a parallel position with respect to the body axis is recommended.

• If the patient is in a hard cervical collar, roll and position him or her with the collar on.

• Include a lower sheet that can be used to support the arms in a sling.

• Place the cervical spine in a neutral position.

• If the patient is in continuous traction, start at 7 lb and increase to 15 lb maximum as necessary.

• Monitor somatosensory evoked potentials (SSEPs) and motor evoked potentials prepositioning and postpositioning.

• Avoid paralytics, because they interfere with neuromonitoring.

Positioning Pitfalls

• Horizontally placed rolls may interfere with chin flexion.

• Proper alignment of cervical spine is critical. Avoid excessive flexion or extension.

• Be aware of chin position during positioning.

• If SSEPs or motor evoked potentials change during positioning, return the patient to the supine position. An option is to administer methylprednisolone per the National Acute Spinal Cord Injury Study (NASCIS II) guidelines.

Positioning Equipment

• Use of cervical traction is advocated by some (Menezes and Sonntag, 1996).

Portals/Exposures

image Occipital inion to C5 (Figure 9-7)

image At a minimum, lateral masses to C3 must be exposed.

image

FIGURE 9-7

Portals/Exposures Pearls

• Care must be taken when exposing the space between the occiput and the C1 interspace. There is a risk of penetrating the dura at this interspace with the Bovie electrocautery or a spinal instrument.

• The vertebral artery lies within the occipital triangle (superior and inferior obliques, rectus capitis). Avoid iatrogenic damage to the artery during lateral dissection.

• Remove soft tissue that could interfere with bony fusion, such as the atlantooccipital membrane, interspinous ligaments, and ligamentum flavum.

Portals/Exposures Pitfalls

• Adequate exposure of laminae/lateral masses must be achieved to direct sublaminar wires or pedicle/lateral mass screws.

• Avoid excessive electrocautery, which damages underlying bone.

• Do not forget to decorticate cortical surfaces. Doing so promotes fusion.

Portals/Exposures Equipment

• Fluoroscopy for pedicle/lateral mass screws placement

• Neuronavigation for instrumentation placement

Procedure

Step 1

image Position the patient on gel rolls, in pins, in a prone, neutral position (Figure 9-8).

image Shave and mark from the inion down the midline to C5.

image Prepare skin in the usual sterile fashion.

image Give preoperative antibiotics.

image

FIGURE 9-8

Step 1 Pearls

• Avoid excessive flexion/extension; a near-anatomic position is preferred.

• Chin clearance must be obtained.

• Monitoring of SSEPs and motor evoked potentials is recommended.

• If tolerated by the patient, the patient’s neck may be positioned to optimize a surgical approach and then repositioned under fluoroscopic guidance for final fixation.

Step 1 Controversies

• Some surgeons advocate using traction and avoiding pin fixation (Menezes and Sonntag, 1996).

Step 2: Exposure of Inion to C5

image Dissect using sharp, blunt, and electrocautery dissection down the midline through the following layers (see Figure 9-7):

• Superficial fascia: identify the midline raphe.

• Identify the spinous process and the prevertebral fascia.

• Dissect bilaterally down the spinous processes. Preserve the ligamentum nuchae as much as possible.

• Take care to identify the spinous process of C2 and the ring of C1. Dissection here must be done very cautiously to avoid entering the occipital, C1, or C2 spaces or the C1-2 interspace.

• Expose laterally to identify lateral masses.

• Expose anteriorly to identify the inion.

• At a minimum, bony exposure of occiput to C2 lateral masses must be achieved. Expose lower lateral masses as needed.

Step 2 Pearls

• Minimize electrocautery to prevent damage to the dura or underlying bone (for fusion).

• Minimize the length of the exposure.

Step 2 Pitfalls

• Avoid past pointing into the interlaminar or occipital lamina space with electrocautery.

Step 3: Instrumentation and Fusion

image Place the occipital Kiel plate in the midline (Figure 9-9).

image Place an isthmus or pedicle screw at C2. (Expose the lateral masses of distal vertebrae as needed.)

image Contour the rods to the approximate neutral position of the occipital-cervical junction. The rod bend should be approximately a 130-degree angle, but this will vary with each patient.

image Connect the rods to the Kiel plate and screw.

image Decorticate the occipital-cervical junction.

image Pack the construct with autologous/allograft material to encourage fusion.

image

FIGURE 9-9

Step 3 Pearls

• Create the shortest construct possible without sacrificing stability. Longer constructs tend to minimize mobility; on the other hand, to short a construct may be inadequate for creating appropriate stability.

• In traumatic injury, the construct should include the first two levels with normal ligamentous anatomy.

Step 3 Pitfalls

• Radiographically evaluate occiput anatomy before placement of plate. Be aware of thickness of occiput.

• Avoid excessive manipulation of spinal instrumentation. Nicks, scratches, and deformities will all serve as focal points for mechanical failure.

Step 3 Instrumentation/Implantation

• Screw/rod constructs

• Wire-based systems

Step 4: Closure

image Close layers sequentially.

image Subfascial drain is used as needed.

Step 4 Pearls

• Appropriate approximation of skin rolls is needed in patients with large necks.

Controversies

• Use of autologous bone versus allograft bone: Autologous bone has high fusion rates, but there is higher morbidity associated with hip graft harvest.

Postoperative Care and Expected Outcomes

image Place the patient in a hard collar for 6 to 12 weeks with radiographic follow-up.

image After 6 to 12 weeks, flexion/extension views should be obtained to determine if fusion is noted radiographically.

image Approximately 80% fusion rates are expected.

image Complications include infection, neurovascular compromise from instrumentation, subdural or subarachnoid hematoma resulting from instrumentation placement, cerebrospinal fluid-flow abnormalities resulting from instrumentation placement, pullout of screws/plate/instrumentation, and fracture/migration of instrumentation.

Postoperative Pearls

• For patients with poor bone quality, postoperative halo fusion can be considered.

• Consider use of bone stimulators for patients at risk of poor fusion.

Postoperative Pitfalls

• Beware of postoperative radiation and chemotherapy for oncology patients. Do not start prior to 2 weeks after surgery.

• Balance training and physical therapy are important.

• Instrumentation will fail without bony fusion.

Postoperative Controversies

• Not all surgeons advocate use of a hard cervical collar postoperatively.

Evidence

Abumi K, Takada T, Shono Y, Kaneda K, Fujiya M. Posterior occipitocervical reconstruction using cervical pedicle screws and plate-rod systems. Spine. 1999;24:1425-1434.

Deutsch H, Haid JrRW, Rodts JrGE, Mummaneni PV. Occipitocervical fixation: long-term results. Spine. 2005;30:530-535.

Dvorak MF, Sekeramayi F, Zhu Q, et al. Anterior occiput to axis screw fixation. Part II: a biomechanical comparison with posterior fixation techniques. Spine. 2003;28:239-245.

Fehlings MG, Cadotte DW. Occipital cervical fusion: an evolution of techniques. J Neurosurg Spine. 2010;13:3-4.

Lee SC, Chen JF, Lee ST. Complications of fixation to the occiput—anatomical and design implications. Br J Neurosurg. 2004;18:590-597.

Menezes AH, Sonntag VKH, editors. Principles of Spinal Surgery. New York: McGraw-Hill;, 1996.

Oda I, Abumi K, Sell LC, et al. Biomechanical evaluation of five different occipito-atlanto-axial fixation techniques. Spine. 1999;24:2377-2382.

Schmidek HH, Sweet WH, editors: Schmidek & Sweet’s Operative Neurosurgical Techniques: Indications, Methods, and Results. Philadelphia;WB Saunders: 2000:1934-1945

Takechi Y, Iizuka H, Sorimachi Y, et al. Non-traumatic posterior atlanto-occipital joint dislocation. Case report. Eur Spine J. 2010;20(Suppl 2):S172-S175.

Vaccaro AR, Betz RR, Zeidman SM, editors: Principles and Practice of Spine Surgery. St Louis;CV Mosby: 2003:723-725

Vender JR, Rekito AJ, Harrison SJ, McDonnell DE. The evolution of posterior cervical and occipitocervical fusion and instrumentation. Neurosurg Focus. 2004;16:e9.

Winegar CD, Lawrence JP, Friel BC, et al. A systematic review of occipital cervical fusion: techniques and outcomes. A review. J Neurosurg Spine. 2010;13:5-16.

Winn HR, Youmans JR, Winn HR, Youmans JR, editors. Youmans Neurological Surgery. Philadelphia: WB Saunders, 2004.

Related posts:

17: Anterior Thoracolumbar Spinal Fusion via Open Approach for Idiopathic Scoliosis 13: Cervical Pedicle Screw Fixation 29: Spondylolysis Repair 39: Lumbar Internal Laminectomy 25: Sacropelvic Fixation 2: Halo Placement in the Pediatric and Adult Patient