Posterior Approach to Cervical Degenerative Disease

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CHAPTER 279 Posterior Approach to Cervical Degenerative Disease

Peter D. Angevine, Paul C. McCormick

Surgical approaches for the management of degenerative disorders of the cervical spine, including herniated disk and spondylosis, may be broadly segregated into anterior and posterior approaches. Recent evidence-based guidelines have reported that there is insufficient evidence to recommend one surgical approach over another for the treatment of cervical spondylotic myelopathy (CSM).1 Although in many cases a clearly superior approach may not be evident, understanding the specific techniques and advantages and disadvantages of each will allow the surgeon to make informed, rational decisions.

The posterior approach is familiar to all spine surgeons. It has the additional advantages of avoiding the visceral, vascular, and neural structures of the anterior aspect of the neck. The incidence of postoperative dysphagia and dysphonia is correspondingly lower than that with anterior procedures. The posterior exposure can easily be extended rostrally and caudally as necessary, including extension to the occipital and thoracic regions. Although procedures performed from a posterior approach often involve surgical arthrodesis with or without instrumentation, another advantage of the approach is that effective decompression can be achieved without necessarily performing a concomitant fusion. Laminectomy and laminaplasty procedures can, in appropriate patients, effectively decompress the spinal canal while preserving motion in the cervical spine.

On the negative side, however, posterior approaches are generally associated with greater postoperative neck pain than is the case with anterior surgery because of the more extensive muscular dissection required. Restoration of lordosis, particularly in an osteopenic patient, can be difficult from a solely posterior approach; anterior interbody support plus correction is often a more powerful technique if hypolordosis is a significant concern. The infection rate with posterior approaches is higher than that with anterior approaches.2 This is more reflective of an extremely low rate of infection with anterior cervical surgery than of a high rate with the former.

The procedures that may be performed with a posterior approach to the cervical spine for the management of degenerative disease are many and range from simple foraminotomy to laminectomy and instrumented fusion. Many factors are considered in selecting the appropriate approach and the specific procedure most likely to provide the maximum clinical benefit for the patient. The decision is based on the findings of a thorough clinical and imaging evaluation.

Clinical Evaluation

As for any patient, a complete clinical evaluation including a directed history and physical examination is the essential first step in the work-up of a patient with degenerative cervical disease. The history and physical examination should be directed toward establishing or confirming the diagnosis and understanding the impact of the disorder on the patient’s quality of life. Signs and symptoms of cervical radiculopathy or myelopathy or frequently a combination of the two may be present.

As the diagnosis is confirmed and the course of the disease established, the presence or absence of factors that may affect the surgical strategy is determined. The patient is queried regarding the presence, nature, location, quality, and intensity of the neck pain. Exacerbating and ameliorating factors are identified. A history of previous neck or cervical spine surgery is elicited. The patient’s occupation and any serious avocations are determined; of particular interest are activities that involve speaking or singing. The patient is specifically interrogated regarding any swallowing dysfunction. Any of these factors may favor the use of a posterior approach.

Imaging

Adequate imaging evaluation usually includes anteroposterior, lateral, and lateral flexion-extension cervical radiographs (including the occiput through T1) and either magnetic resonance imaging (MRI) or computed tomography (CT), the latter with or without preceding myelography. In some cases both MRI and CT will be desirable. Oblique radiographs, flexion-extension MRI, or other studies may be obtained in specific cases.

The three most important factors in determining whether a posterior (dorsal) approach to cervical degenerative disease is appropriate or feasible are the location of the disease (dorsal or ventral), the extent of disease (number of spinal segments involved), and the alignment of the cervical spine (lordotic, straight, or kyphotic). Compression that is purely dorsal or dorsolateral is generally best relieved with surgery from a posterior approach. A common scenario involves a patient in the seventh or eighth decade with a thick, buckling ligamentum flavum causing multisegmental spinal cord compression. Occasionally, such a patient is initially seen after a fall with an acute neurological deficit (Fig. 279-1).

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FIGURE 279-1 Multilevel cervical spondylosis with an acute neurological injury after minor trauma.

Pathology that extends over many cervical segments, particularly if it crosses into the thoracic spine, is often treated preferably via a posterior approach. Degenerative spinal disease superimposed on a congenitally narrow canal (<12 mm, identified on a lateral radiograph by near-superimposition of the posterior cortex of the lateral masses and the spinolaminar line) is one such situation. Another condition that often involves multiple segments at initial evaluation is ossification of the posterior longitudinal ligament (OPLL) (Fig. 279-2). The typically extensive, confluent disease seen with OPLL ossification is often optimally approached posteriorly, particularly because the ventral dura is frequently annealed to the ossified ligament and a spinal fluid leak is unavoidable if an anterior approach is used.

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FIGURE 279-2 Midline sagittal magnetic resonance image (A) and computed tomography scan (B) of a patient with symptomatic multilevel, confluent ossification of the posterior longitudinal ligament. Such patients are often best treated with a posterior approach.

The alignment of the cervical spine can be an important factor in determining the surgical approach. In general, a posterior approach is best suited for treating patients with straight or lordotic alignment. With all other factors constant, dorsal decompression (laminectomy) is less effective in relieving compression in a kyphotic spine than in a lordotic spine. Another consideration is the need to correct the patient’s alignment in the sagittal plane. A posterior-only approach may not be the optimal method for correcting alignment of the cervical spine. The methods of posterior fixation offer limited resistance to pullout and few salvage options. Anterior interbody grafting may provide a superior option for the restoration of segmental lordosis.

Indications for Surgical Treatment

Surgical treatment of cervical degenerative disorders, such as CSM or radiculopathy, may be indicated in patients with progressive signs of myelopathy, progressive or severe weakness in a cervical myotome, or intractable radicular pain and correlative imaging. The natural history of CSM is variable and unpredictable for any particular patient.3 Recommendations may be tailored to the patient based on age, symptoms, and findings on electromyography (EMG) or radiography, among other factors.4 Once progression has been demonstrated, however, it is unlikely that the process will halt completely or reverse spontaneously.5 In these circumstances, a frank, clear discussion should be held with the patient and family regarding the potential risks associated with surgical intervention versus the risks associated with continued observation.

Anesthesia and Positioning

General anesthesia is used for all posterior cervical surgery at our institution. If two 20-gauge or larger peripheral intravenous lines are placed, central venous access is usually unnecessary. An arterial line is established to allow close monitoring of arterial blood pressure. A Foley catheter is inserted, and sequential compression devices are placed on the legs.

If Lhermitte’s sign or other symptoms develop with cervical extension, awake fiberoptic intubation is performed. Conversely, if the patient is able to achieve adequate extension without symptoms, intubation with direct larygoscopy is preferred. Meticulous attention is paid to systolic blood pressure during induction and until the spinal cord is decompressed. In the absence of contraindications, the anesthesiologist is instructed to maintain systolic blood pressure at greater than 120 mm Hg to optimize spinal cord perfusion.

We use the prone position exclusively for posterior cervical surgery. Based on surgeon preference, either an electric operating table with padded bolsters and a rigid Mayfield head holder or a Jackson spine table with Gardner-Wells traction is used. With the Jackson table, a bivector traction setup with two ropes is used to permit the patient to be positioned initially in relative cervical flexion to facilitate the decompressive portion of the procedure and placement of the fixation points. The weight is moved to the upper rope to enhance cervical lordosis before placement of the rods and performing the arthrodesis (Fig. 279-3). A horseshoe head holder is placed 2 to 3 cm away from the patient’s face to serve as a backup should a problem occur with the traction.

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FIGURE 279-3 Bivector traction is used to facilitate the decompressive portion of the procedure and allow the establishment of normal alignment for instrumentation. A, During the exposure and decompression, the weight (15 lb) is on the lower rope. B, The weight is moved to the upper rope prior to final placement of instrumentation to restore cervical lordosis.

Some surgeons prefer a sitting position for posterior cervical foraminotomies, particularly when the procedure is performed with a minimally invasive technique. Advantages of this position include improved fluoroscopic visualization of the cervicothoracic junction and a nearly bloodless field. Disadvantages include the risk for air embolism and, possibly, a somewhat longer setup time. If a sitting position is used, a precordial Doppler probe and an end-tidal CO2 monitor are recommended to facilitate early detection of an air embolus.

General anesthesia is maintained during the operation with a total intravenous anesthesia technique that allows optimal monitoring of somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs). Most often this means that the use of volatile inhaled anesthetics is avoided or minimized and general anesthesia is maintained with propofol (Diprivan), fentanyl, or sufentanil and nitrous oxide.

Spinal Cord Monitoring

SSEPs and MEPs are monitored routinely in patients with myelopathy undergoing a posterior procedure. Patients with purely radicular symptoms may be monitored depending on the specific pathology and neurological status of the patient, among other factors. In patients with severe compression, radiographic instability, or a rapidly progressive clinical course, we generally record baseline SSEPs after intubation before turning the patient to the prone position. Prepositioning baseline MEPs are not obtained because of the residual effect of the muscle relaxant given to facilitate intubation.

Although we routinely monitor SSEPs and MEPs in these patients, the utility of this strategy and the appropriate response to changes in signal quality, amplitude, or latency in different clinical scenarios are sometimes unclear. We have, on occasion, identified problems with positioning of the arms and shoulders based on monitoring changes. During decompression of a stenotic foramen it is not unusual to see transient nerve root irritation on free-running EMG that has no apparent clinical postoperative correlation. An evidence-based review found conflicting data regarding the use of intraoperative improvements in electrophysiologic data for clinical prognostication.6

The surgeon must, for each individual situation, determine the response to the decrement or loss of SSEP or MEP signals during a posterior cervical procedure. The anesthesiologist and neurophysiologist are queried regarding any recent changes in anesthetic technique and the nature of the identified changes. Initial steps may include increasing blood pressure, inspecting the surgical field for any compression of the spinal cord, and reversing any changes in spinal alignment. These and any further steps are taken at the surgeon’s discretion.

Exposure

The surgeon should maintain meticulous hemostasis during surgical exposure of the posterior cervical spine. This is facilitated by careful surgical technique. After the skin incision is made and the subcutaneous tissue is divided to the cervicodorsal fascia, spending a few moments to identify the avascular plane between the paracervical muscles will pay dividends in achieving a quicker, drier approach. One technique to facilitate identification of this plane is to use the cutting rather than the cautery setting of the monopolar cautery; it will be readily apparent if the dissection proceeds out of plane and into the adjacent muscle. This avascular plane extends ventrally to the spinous processes.

The posterior bony elements are exposed subperiosteally with monopolar cautery. The exposure extends to the junction of the lamina and the lateral masses. The lateral masses and facet joints are not exposed only if a decompressive procedure is to be performed. If motion-preserving decompression with intrasegmental implants is planned, such as a laminaplasty with plate reconstruction, the lateral masses are exposed while taking care to preserve the facet capsules. When a laminectomy with arthrodesis is planned, the lateral masses and facet joints are exposed and the articular surfaces removed at all levels of the planned fusion. Regardless of the procedure, it is essential to try to preserve the dorsal midline soft tissue structures connecting the vertebrae at the ends of the operative segments to the adjacent nonoperative segments, particularly the interspinous and supraspinous ligaments. This posterior tension band is important for maintenance of alignment of the transitional segments from the operated to unoperated regions.

Minimally invasive techniques involving sequential muscle dilation and tubular retractors may be used for unilateral one- and two-level foraminotomies. A longitudinal paramedian incision is planned under fluoroscopic guidance. The incision is made and continued ventrally through the fascia. Under fluoroscopic control, the localizing needle and sequentially larger muscle dilators are introduced. The ideal exposure is centered over the intervertebral space with the medial half of the lateral mass in the lateral half of the operative field. A microscope or endoscope is used for illumination and magnification.

Foraminotomy/Diskectomy

The posterior keyhole foraminotomy as first described by Scoville has a role in the treatment of isolated foraminal stenosis or lateral disk herniation.7 Patients with symptoms referable to a single cervical nerve root are the best candidates for this procedure. Bone removal is tailored to the nature of the pathology. In patients with spondylosis and osteophytic foraminal stenosis, a keyhole-shaped decompression extending from the lateral thecal sac to the lateral border of the pedicle is performed to achieve complete decompression of the exiting nerve root. For the removal of lateral soft herniated disks, a smaller amount of bone can be removed to preserve the majority of the facet joint.

A herniated cervical disk impinges on the exiting nerve root that corresponds to the pedicle caudal to the disk space (e.g., a C5-6 herniated disk causes C6 impingement). The foraminotomy is performed at the appropriate interspace just proximal to the pedicle of the level caudal to the disk herniation (Fig. 279-4). The first part of the foraminotomy procedure consists of a small laminotomy and flavectomy to expose the lateral dura and the origin of the exiting nerve root. The foraminotomy is extended laterally by using a high-speed drill to thin the ventromedial superior facet. Bone removal is completed with small straight and up-going curets. A minimal amount of the inferior facet is removed. After the axilla of the exiting nerve root is identified and a portion of the root approximately 2 to 3 mm in length is exposed, a micro–nerve hook is used to dissect parallel with the nerve root along its caudal edge. With removal of less than half the facet joint, up to 5 mm of the nerve root may be exposed.8 The pedicle is palpated, the nerve hook is then rotated ventral to the root, and the disk herniation is identified. A microdissector or micro–nerve hook may be used to place gentle retraction on the nerve root to expose the disk fragment, which is removed with micro–pituitary rongeurs. Complete decompression of the nerve root is confirmed with passage of the micro–nerve hook through the foramen dorsal and ventral to the nerve root. During the dissection or after the decompression, hemostasis of the epidural veins is accomplished with thrombin-soaked collagen in either a patty (Gelfoam, Pharmacia & Upjohn, New York) or semiliquid (FloSeal, Baxter, Deerfield, IL) formulation.

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FIGURE 279-4 Laminoforaminotomy for radiculopathy.

The technique for performing a foraminotomy to treat nerve root compression and radiculopathy secondary to cervical spondylosis with facet hypertrophy or ventral osteophytes, or a combination of both, also starts with a small lateral laminotomy. The high-speed drill, usually with a 2-mm round bur, is then used to remove the inferomedial portion of the inferior facet. Less than half of the facet (medial-lateral) is removed. Such removal can be done very rapidly because the superior facet is located between the inferior facet and the nerve root. The drill is then used to remove a portion of the superior facet that corresponds to the preceding removal of bone. This is typically accomplished with two cuts, one extending transversely in line with the proximal edge of the pedicle and the other in the sagittal plane no more lateraly than the midpoint of the facet. After these cuts have been completed, the small remaining free piece of superior facet is removed and the nerve root is seen ventrally. A micro–nerve hook is used to palpate the pedicle and confirm complete decompression of the nerve root. Occasionally, a small ledge of bone at the cephalomedial edge of the pedicle remains and may cause persistent nerve root compression. This and any other additional bone removal needed is performed with small curets.

Laminectomy and Laminaplasty

When central canal stenosis is present, laminectomy or laminaplasty is necessary to achieve decompression. Either procedure, when performed correctly, can accomplish the goal of enlarging the space available for the spinal cord. With laminaplasty, the canal is expanded but the posterior elements are not removed completely. This may reduce postoperative pain by preventing scarring of the muscles to the dura. It may also reduce the development of postlaminectomy kyphosis by helping preserve the posterior structures.

Both procedures are most effective in relieving compression caused by dorsally located pathology. Ventral compression may also be relieved by posterior decompression under certain circumstances. First, a sufficient rostral-caudal extent of the canal must be decompressed to ensure that the spinal cord is not compressed against the edge of the decompression. Second, the cervical spine should be lordotic, or at least straight, in the region of the pathology so that the spinal cord will tend to lift away from the compression after release or removal of the dorsal elements. A laminectomy or laminaplasty will not effectively decompress the spinal cord in a kyphotic region without realignment of the spine. The dorsal decompression may, in fact, lead to progression of the kyphosis secondary to disruption of the posterior tension band. With proper patient selection and care in avoiding disruption of the facet joints, however, good long-term results may be achieved with laminectomy alone (Fig. 279-5).

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FIGURE 279-5 Preoperative (A) and 18-month postoperative (B) lateral cervical radiographs of a patient who underwent multilevel laminectomies for cervical spondylotic myelopathy.

After the appropriate dorsal exposure, foraminotomies are performed when necessary. The next step for either laminectomy or laminaplasty is to drill a trough through the laminae at the operative levels on one side. This trough is the width of the drill bit (2 to 3 mm) and is located at the junction of the lamina and the facet.

To perform a laminaplasty, a partial-thickness trough is drilled on the contralateral side in the corresponding location. It is important that this trough be straight for the length of the laminaplasty to prevent adjacent laminae from impinging on each other when they are hinged open. The depth of the trough is important as well to allow the laminae to be greensticked open but remain attached to the lateral masses. In most cases it is sufficient to drill to the ventral cortex of the laminae; attention must also be paid to removal of the cortex at the rostral and caudal aspect of each lamina.

After completion of the hinge-side trough, the laminaplasty is carefully opened. The ligamentum flavum at the rostral and caudal limits of the decompression must be thinned or removed. A small up-going curet is placed underneath the cut edge of one of the central laminae, and gentle pressure is placed on the spinous process at the same level. By elevating the cut edge with the curet and simultaneously pressing on the spinous process, the laminaplasty is gradually opened. Applying pressure to two points safeguards against the laminae snapping back and striking the spinal cord if one point fails.

There are several ways to maintain the laminaplasty opening. Small titanium plates may be affixed to the lateral mass and the lamina with small screws. There are plates made especially for this purpose. Alternatively, instrumentation from a maxillofacial fracture repair set may be adapted for use. The plate is anchored to the center of the lateral mass to avoid impingement on the adjacent facet joints. An alternative or supplemental method to maintain the laminaplasty is to place a spacer, either bone or synthetic, into the opening and suture or wire it in place (Fig. 279-6).

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FIGURE 279-6 Preoperative (A) and postoperative (B) sagittal magnetic resonance images and postoperative lateral radiograph (C) of a patient with cervical stenosis and myelopathy who underwent multilevel open-door laminaplasty for decompression.

To perform a laminectomy, a second full-thickness trough is drilled contralateral to the first. Sharp up-going curets and small Kerrison punches are used to divide the ligamentum flavum at the rostral and caudal ends of the operative segment. The caudal spinous process is grasped with a Leksell rongeur or Kocher clamp, and firm, steady, upward tension is applied. The lateral edge of the ligamentum flavum may also need to be released, but the laminae will then be able to be peeled away from the canal. The assistant watches to ensure that the rostral lamina does not rotate into the spinal canal but is instead lifted away with the other laminae. The bone is cleaned and morselized for use in the arthrodesis, if one is to be performed.

Cervical Posterior Segmental Instrumentation

Posterior segmental instrumentation of the cervical spine may be indicated in several scenarios. In degenerative disorders it is most often performed to restore or maintain spinal alignment in patients with a kyphotic or straight spine or significant degenerative instability manifested as spondylolisthesis. It may be performed alone or in combination with an anterior procedure.

C2 Instrumentation

In rare cases is it necessary to obtain fixation above C2 for the treatment of typical cervical degenerative disease. Atlantoaxial instability is the subject of a separate chapter in this text, and fixation of the occiput and atlas are also discussed elsewhere in this text. C2 fixation is reviewed here because it is not uncommon for posterior constructs to extend rostrally to the axis.

The main fixation options for C2 are pedicle screws, pars interarticularis (“pars”) screws, and translaminar screws. All of these options can provide secure fixation of the axis and may be appropriate in different situations. Any surgeon who regularly performs posterior cervical surgery should be familiar with all three techniques because any one option may not be safe or possible in an individual patient.

Pars screws are distinguished from pedicle screws by their length, entry points, and trajectories. For pars screws, the entry point is more caudal and medial and the trajectory more straight ahead than for C2 pedicle screws. Screw lengths also tend to be shorter. With either technique, the surgeon must carefully review the preoperative imaging to ensure that the vertebral artery’s location and size do not preclude safe placement of either type of screw. Some surgeons perform stereotaxic CT scans preoperatively and review the possible screw trajectories on a workstation. We have found paramedian sagittal plane reconstructed images to be adequate for this purpose. If the minimum distance between the vertebral artery and both the superior facet of C2 and the spinal canal is 4 mm or greater, there is generally sufficient room to safely pass a screw.

The starting point for the pars screw is 2 to 3 mm rostral and a similar distance lateral to the junction of the caudal lamina and the inferior facet. It can be helpful to dissect along the lateral aspect of the rostral edge of the lamina onto the medial pars to confirm proper screw trajectory. Lateral fluoroscopy may be used to determine the sagittal trajectory, which is optimally parallel to the rostral edge of the lamina and pars. The overall trajectory is similar to that of a C1-2 transarticular screw except that it is slightly less rostrally directed to avoid violation of the C1-2 joint. Based on preoperative imaging, a 16-mm-long screw is typically selected so that it stops short of the transverse foramen.9

The starting point for the pedicle screw is more rostral and lateral than that for the pars screw. Useful landmarks are the rostral edge of the lamina and a point just lateral to the midpoint of the pars. Again, dissection along the medial pars lateral to the thecal sac can facilitate determination of the lateral to medial trajectory. The rostrocaudal angle is approximately 20 degrees, and the screw is directed 15 to 25 degrees medially.9 Screw lengths of 20 to 24 mm may be placed safely with this trajectory.

An alternative technique for achieving fixation at C2 that does not place the vertebral artery at risk was first described by Wright in 2004.10 Bilateral crossing translaminar screws may be placed safely in many patients in whom placement of axial pars or pedicle screws is not possible or thought to be dangerous. The CT or MRI scans are examined preoperatively to ensure that the lamina is sufficiently thick to contain a 3.5- or 4-mm-diameter screw. The entry point is at the junction of the spinous process and the lamina, and the screw is directed contralaterally toward the C2 inferior facet. Screws up to 30 mm in length may be placed. One obvious disadvantage of this technique versus pars or pedicle fixation is that concomitant or subsequent C2 laminectomy is not possible.

Lateral Mass Screw Fixation

In the subaxial spine, the lateral masses provide the most secure points for fixation. Multiaxial screws 3.5 to 4.0 mm in diameter and up to 16 mm in length can routinely be placed segmentally. C3 through C6 are the most commonly instrumented levels; the lateral masses at C7 are often thin and angled obliquely, which makes screw placement in the lateral mass tenuous. Because the pedicles of C7 are relatively large and easily instrumented, pedicle screws are frequently used at this level when fixation is necessary.

Several techniques for the insertion of lateral mass screws have been described. Jeannert and Magerl described a technique of insertion that maximizes the length of the screw while directing it away from the nerve root and vertebral artery. They described a starting point slightly medial and cranial to the geometric center of the lateral mass; using a point slightly caudal to that can help optimize the length of the screw and minimize interference with the cranially adjacent facet joint.10a This location is marked with a small bur. A twist drill with a depth stop is then used to drill the pilot hole. The angle is approximately 20 to 30 degrees medial to lateral and parallel to the facet joints. The hole is drilled until the ventral cortex is breached. This may occur at a depth between 12 and 16 mm or greater, depending on the patient’s size, the presence of osteophytes, and the precise trajectory taken. The depth is measured directly, the hole is tapped, and the screw is placed.

The rods are contoured to match the sagittal alignment and secured to the screws (Fig. 279-7). Current multiaxial lateral mass screws can accommodate minor variations in sagittal and coronal alignment of the screws. It is important, however, to minimize the force exerted on any individual screw to avoid the possibility of fixation failure. Cross-linkages to increase construct rigidity are available for most instrumentation systems.

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FIGURE 279-7 Anteroposterior (A) and lateral (B) postoperative radiographs demonstrating lateral mass screw fixation of the subaxial cervical spine.

Closure

Meticulous closure technique is essential to minimize wound complications. Before placing a bone graft, thorough irrigation is performed with sterile solution. Any necrotic tissue is sharply débrided and hemostasis achieved. Subfascial and suprafascial drains are placed at the surgeon’s discretion. The paraspinal muscles are loosely apposed with running synthetic absorbable monofilament suture. The fascia is tightly closed with interrupted absorbable braided synthetic suture. The subcutaneous tissue is closed in multiple layers to ensure that all dead space is obliterated. The skin is closed with a running subcuticular synthetic monofilament suture.

Complications and Avoidance

Close attention must be paid during induction and positioning of severely myelopathic patients to minimize the likelihood of a neurological complication. In general, normotension should be maintained, ideally with systolic blood pressure higher than 120 mm Hg. Fiberoptic intubation or the use of an intubating laryngeal mask airway may reduce the amount of cervical extension needed to place the endotracheal tube. During positioning, one team member should be responsible for maintaining the neck in neutral alignment until the head is secured.

Postoperative dissociated motor loss has been reported to occur in 5% to 8% of patients after cervical laminaplasty.11,12 The most commonly involved root is C5; the next most common is C6. It is manifested as painless deltoid or biceps weakness and may be more common in patients with more severe foraminal or central stenosis preoperatively. Monitoring of free-running EMG signals from the biceps and deltoids may demonstrate signs of nerve root irritation, but there are no definitive data that such monitoring reduces the incidence of this complication. Ensuring complete decompression of the nerve root may also help reduce the risk.

Injury to the vertebral artery or nerve root is a risk with placement of screws in the lateral mass. Ensuring that the screw trajectory is directed laterally will minimize the likelihood of violating the vessel, which generally lies ventral to the medial half of the lateral mass. If a vertebral artery injury is suspected intraoperatively, it is important that one not perform any further procedures that might place the contralateral vessel at risk. A short screw may be placed at the level of the violation to help tamponade the bleeding. No attempt is made to visualize the vessel or to perform a direct repair. After completion of the procedure, an angiogram may be obtained immediately with the possibility of stent placement if a dissection is seen. If the patient is stable, a magnetic resonance angiogram or formal angiography may be deferred to postoperative day 1.

Outcomes

Although there are many historical reports of the results of posterior surgery for cervical degenerative disease, the literature suffers from a paucity of studies reporting outcomes with validated outcomes instruments.6 There are also few comparative studies of surgical techniques, and those that do exist are generally of low evidential quality and thus preclude meaningful conclusions.13–19 Outcomes may be expected to depend, in large part, on the type of pathology present rather than on the specific procedure, assuming that the operation effectively addresses the pathology.

Retrospective studies report good to excellent outcomes on mostly nonvalidated outcome measures for 70% to 98% of patients treated with laminoforaminotomy for cervical radiculopathy.20–26 The proportion of patients in whom improvement is achieved may depend to some degree on the specific symptoms present; one study has reported that pain resolves more reliably than weakness, which improves in more patients better than sensory abnormalities do.20

There are mixed data regarding prognostic factors for patients undergoing surgery for CSM. A longer duration of symptoms and the presence of more severe symptoms do seem to correlate with a lower likelihood of significant improvement or a lesser degree of improvement than seen in patients with a shorter or less severe symptomatic period preoperatively; the effect may vary with patient age.27–29

Multiple uncontrolled studies of cervical laminectomy, laminectomy and fusion, and laminaplasty have reported significant clinical improvement in patients with myelopathy.30–37 All these studies suffer from the methodologic limitations of noncomparative study designs. Comparisons of outcomes of specific techniques are likewise fraught with potential bias, and absolute statements about the relative effectiveness of one procedure versus another are not warranted based on current evidence.38–40

Conclusion

The posterior approach to the cervical spine is an established, effective option for the management of degenerative spinal diseases causing radiculopathy and myelopathy. Specific procedures include laminoforaminotomy, laminectomy, laminectomy and fusion, and laminaplasty. There are particular circumstances in which one of these procedures is clearly preferable to the others, but in other situations more than one technique may be appropriate. Familiarity with all the techniques and their indications, advantages, and potential risks will allow the surgeon to provide the best possible care for patients with cervical degenerative disease.

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Gonzalez-Feria L, Peraita-Peraita P. Cervical spondylotic myelopathy: a cooperative study. Clin Neurol Neurosurg. 1975;78:19-33.

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Hamanishi C, Tanaka S. Bilateral multilevel laminectomy with or without posterolateral fusion for cervical spondylotic myelopathy: relationship to type of onset and time until operation. J Neurosurg. 1996;85:447-451.

Handa Y, Kubota T, Ishii H, et al. Evaluation of prognostic factors and clinical outcome in elderly patients in whom expansive laminoplasty is performed for cervical myelopathy due to multisegmental spondylotic canal stenosis. A retrospective comparison with younger patients. J Neurosurg. 2002;96:173-179.

Heary RF, Ryken TC, Matz PG, et al. Cervical laminoforaminotomy for the treatment of cervical degenerative radiculopathy. J Neurosurg Spine. 2009;11:198-202.

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Houten JK, Cooper PR. Laminectomy and posterior cervical plating for multilevel cervical spondylotic myelopathy and ossification of the posterior longitudinal ligament: effects on cervical alignment, spinal cord compression, and neurological outcome. Neurosurgery. 2003;52:1081-1088.

Huang RC, Girardi FP, Poynton AR, et al. Treatment of multilevel cervical spondylotic myeloradiculopathy with posterior decompression and fusion with lateral mass plate fixation and local bone graft. J Spinal Disord Tech. 2003;16:123-129.

Kaminsky SB, Clark CR, Traynelis VC. Operative treatment of cervical spondylotic myelopathy and radiculopathy. A comparison of laminectomy and laminoplasty at five year average follow-up. Iowa Orthop J. 2004;24:95-105.

Kihara S, Umebayashi T, Hoshimaru M. Technical improvements and results of open-door expansive laminoplasty with hydroxyapatite implants for cervical myelopathy. Neurosurgery. 2005;57:348-356.

Korinth MC, Kruger A, Oertel MF, et al. Posterior foraminotomy or anterior discectomy with polymethyl methacrylate interbody stabilization for soft disc disease: results in 292 patients with monoradiculopathy. Spine. 2006;31:1207-1216.

Kumar GR, Maurice-Williams RS, Bradford R. Cervical foraminotomy: an effective treatment for cervical spondylotic radiculopathy. Br J Neurosurg. 1998;12:563-568.

Kumar VG, Rea GL, Mervis LJ, et al. Cervical spondylotic myelopathy: functional and radiographic long-term outcome after laminectomy and posterior fusion. Neurosurgery. 1999;44:771-777.

LaRocca H. Cervical spondylotic myelopathy: natural history. Spine. 1988;13:854-855.

Matsunaga S, Sakou T, Nakanisi K. Analysis of the cervical spine alignment following laminoplasty and laminectomy. Spinal Cord. 1999;37:20-24.

Matz PG, Anderson PA, Groff MW, et al. Cervical laminoplasty for the treatment of cervical degenerative myelopathy. J Neurosurg Spine. 2009;11:157-169.

Matz PG, Anderson PA, Holly LT, et al. The natural history of cervical spondylotic myelopathy. J Neurosurg Spine. 2009;11:104-111.

Mummaneni PV, Haid RW. Atlantoaxial fixation: overview of all techniques. Neurol India. 2005;53:408-415.

Mummaneni PV, Kaiser MG, Matz PG, et al. Cervical surgical techniques for the treatment of cervical spondylotic myelopathy. J Neurosurg Spine. 2009;11:130-141.

Ratliff JK, Cooper PR. Cervical laminoplasty: a critical review. J Neurosurg. 2003;98:230-238.

Raynor RB. Anterior or posterior approach to the cervical spine: an anatomical and radiographic evaluation and comparison. Neurosurgery. 1983;12:7-13.

Resnick DK, Anderson PA, Kaiser MG, et al. Electrophysiological monitoring during surgery for cervical degenerative myelopathy and radiculopathy. J Neurosurg Spine. 2009;11:245-252.

Ryken TC, Heary RF, Matz PG, et al. Cervical laminectomy for the treatment of cervical degenerative myelopathy. J Neurosurg Spine. 2009;11:142-149.

Shamji MF, Cook C, Tackett S, et al. Impact of preoperative neurological status on perioperative morbidity associated with anterior and posterior cervical fusion. J Neurosurg Spine. 2008;9:10-16.

Uematsu Y, Tokuhashi Y, Matsuzaki H. Radiculopathy after laminoplasty of the cervical spine. Spine. 1998;23:1443-1448.

Wright NM. Posterior C2 fixation using bilateral, crossing C2 laminar screws. Case series and technical note. J Spinal Disord Tech. 2004;17:158-162.

Yamazaki T, Yanaka K, Sato H, et al. Cervical spondylotic myelopathy: surgical results and factors affecting outcome with special reference to age differences. Neurosurgery. 2003;52:122-126.

Yonenobu K, Fuji T, Ono K, et al. Choice of surgical treatment for multisegmental cervical spondylotic myelopathy. Spine. 1985;10:710-716.

Zeidman SM, Ducker TB. Posterior cervical laminoforaminotomy for radiculopathy: review of 172 cases. Neurosurgery. 1993;33:356-362.

References

1 Mummaneni PV, Kaiser MG, Matz PG, et al. Cervical surgical techniques for the treatment of cervical spondylotic myelopathy. J Neurosurg Spine. 2009;11:130-141.

2 Shamji MF, Cook C, Tackett S, et al. Impact of preoperative neurological status on perioperative morbidity associated with anterior and posterior cervical fusion. J Neurosurg Spine. 2008;9:10-16.

3 LaRocca H. Cervical spondylotic myelopathy: natural history. Spine. 1988;13:854-855.

4 Matz PG, Anderson PA, Holly LT, et al. The natural history of cervical spondylotic myelopathy. J Neurosurg Spine. 2009;11:104-111.

5 Clark E, Robinson PK. Cervical myelopathy: a complication of cervical spondylosis. Brain. 1956;79:483-510.

6 Resnick DK, Anderson PA, Kaiser MG, et al. Electrophysiological monitoring during surgery for cervical degenerative myelopathy and radiculopathy. J Neurosurg Spine. 2009;11:245-252.

7 Heary RF, Ryken TC, Matz PG, et al. Cervical laminoforaminotomy for the treatment of cervical degenerative radiculopathy. J Neurosurg Spine. 2009;11:198-202.

8 Raynor RB. Anterior or posterior approach to the cervical spine: an anatomical and radiographic evaluation and comparison. Neurosurgery. 1983;12:7-13.

9 Mummaneni PV, Haid RW. Atlantoaxial fixation: overview of all techniques. Neurol India. 2005;53:408-415.

10 Wright NM. Posterior C2 fixation using bilateral, crossing C2 laminar screws. Case series and technical note. J Spinal Disord Tech. 2004;17:158-162.

10a Jeannert B, Magerl F, Ward E, et al. Posterior stabilization of the cervical spine with hook plates. Spine. 1991;165:S56-S63.

11 Chiba K, Toyama Y, Matsumoto M, et al. Segmental motor paralysis after expansive open-door laminoplasty. Spine. 2002;27:2108-2115.

12 Uematsu Y, Tokuhashi Y, Matsuzaki H. Radiculopathy after laminoplasty of the cervical spine. Spine. 1998;23:1443-1448.

13 Carol MP, Ducker TB. Cervical spondylitic myelopathies: surgical treatment. J Spinal Disord. 1988;1:59-65.

14 Gonzalez-Feria L, Peraita-Peraita P. Cervical spondylotic myelopathy: a cooperative study. Clin Neurol Neurosurg. 1975;78:19-33.

15 Hamanishi C, Tanaka S. Bilateral multilevel laminectomy with or without posterolateral fusion for cervical spondylotic myelopathy: relationship to type of onset and time until operation. J Neurosurg. 1996;85:447-451.

16 Heller JG, Edwards CCI, Murakami H, et al. Laminoplasty versus laminectomy and fusion for multilevel cervical myelopathy: an independent matched cohort analysis. Spine. 2001;26:1330-1336.

17 Kaminsky SB, Clark CR, Traynelis VC. Operative treatment of cervical spondylotic myelopathy and radiculopathy. A comparison of laminectomy and laminoplasty at five year average follow-up. Iowa Orthop J. 2004;24:95-105.

18 Matsunaga S, Sakou T, Nakanisi K. Analysis of the cervical spine alignment following laminoplasty and laminectomy. Spinal Cord. 1999;37:20-24.

19 Yonenobu K, Fuji T, Ono K, et al. Choice of surgical treatment for multisegmental cervical spondylotic myelopathy. Spine. 1985;10:710-716.

20 Adamson TE. Microendoscopic posterior cervical laminoforaminotomy for unilateral radiculopathy: results of a new technique in 100 cases. J Neurosurg. 2001;95:51-57.

21 Fessler RG, Khoo LT. Minimally invasive cervical microendoscopic foraminotomy: an initial clinical experience. Neurosurgery. 2002;51:S37-S45.

22 Grieve JP, Kitchen ND, Moore AJ, et al. Results of posterior cervical foraminotomy for treatment of cervical spondylitic radiculopathy. Br J Neurosurg. 2000;14:40-43.

23 Henderson CM, Hennessy RG, Shuey HMJ, et al. Posterior-lateral foraminotomy as an exclusive operative technique for cervical radiculopathy: a review of 846 consecutively operated cases. Neurosurgery. 1983;13:504-512.

24 Korinth MC, Kruger A, Oertel MF, et al. Posterior foraminotomy or anterior discectomy with polymethyl methacrylate interbody stabilization for soft disc disease: results in 292 patients with monoradiculopathy. Spine. 2006;31:1207-1216.

25 Kumar GR, Maurice-Williams RS, Bradford R. Cervical foraminotomy: an effective treatment for cervical spondylotic radiculopathy. Br J Neurosurg. 1998;12:563-568.

26 Zeidman SM, Ducker TB. Posterior cervical laminoforaminotomy for radiculopathy: review of 172 cases. Neurosurgery. 1993;33:356-362.

27 Casotto A, Buoncristiani P. Posterior approach in cervical spondylotic myelopathy. Acta Neurochir (Wien). 1981;57:275-285.

28 Handa Y, Kubota T, Ishii H, et al. Evaluation of prognostic factors and clinical outcome in elderly patients in whom expansive laminoplasty is performed for cervical myelopathy due to multisegmental spondylotic canal stenosis. A retrospective comparison with younger patients. J Neurosurg. 2002;96:173-179.

29 Yamazaki T, Yanaka K, Sato H, et al. Cervical spondylotic myelopathy: surgical results and factors affecting outcome with special reference to age differences. Neurosurgery. 2003;52:122-126.

30 Bishara SN. The posterior operation in treatment of cervical spondylosis with myelopathy: a long-term follow-up study. J Neurol Neurosurg Psychiatry. 1971;34:393-398.

31 Fager CA. Results of adequate posterior decompression in the relief of spondylotic cervical myelopathy. J Neurosurg. 1973;38:684-692.

32 Gorter K. Influence of laminectomy on the course of cervical myelopathy. Acta Neurochir (Wien). 1976;33:265-281.

33 Houten JK, Cooper PR. Laminectomy and posterior cervical plating for multilevel cervical spondylotic myelopathy and ossification of the posterior longitudinal ligament: effects on cervical alignment, spinal cord compression, and neurological outcome. Neurosurgery. 2003;52:1081-1088.

34 Huang RC, Girardi FP, Poynton AR, et al. Treatment of multilevel cervical spondylotic myeloradiculopathy with posterior decompression and fusion with lateral mass plate fixation and local bone graft. J Spinal Disord Tech. 2003;16:123-129.

35 Kihara S, Umebayashi T, Hoshimaru M. Technical improvements and results of open-door expansive laminoplasty with hydroxyapatite implants for cervical myelopathy. Neurosurgery. 2005;57:348-356.

36 Kumar VG, Rea GL, Mervis LJ, et al. Cervical spondylotic myelopathy: functional and radiographic long-term outcome after laminectomy and posterior fusion. Neurosurgery. 1999;44:771-777.

37 Ratliff JK, Cooper PR. Cervical laminoplasty: a critical review. J Neurosurg. 2003;98:230-238.

38 Anderson PA, Matz PG, Groff MW, et al. Laminectomy and fusion for the treatment of cervical degenerative myelopathy. J Neurosurg Spine. 2009;11:150-156.

39 Matz PG, Anderson PA, Groff MW, et al. Cervical laminoplasty for the treatment of cervical degenerative myelopathy. J Neurosurg Spine. 2009;11:157-169.

40 Ryken TC, Heary RF, Matz PG, et al. Cervical laminectomy for the treatment of cervical degenerative myelopathy. J Neurosurg Spine. 2009;11:142-149.

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