AAOS Comprehensive Orthopaedic Review

Section 7 - Spine

Chapter 69. Degenerative Conditions of the Cervical Spine

I. Epidemiology and Pathoanatomy

A. The prevalence of degenerative cervical conditions is only slightly less than that of low back pain.

 

B. Disease progression

 

1. The outer anulus in a normal disk is mostly type I collagen; the inner nucleus is type II collagen.

 

2. With age, the ratio of keratin sulfate to chondroitin sulfate increases and water content decreases, leading to a cascade of secondary degenerative events (spondylosis), starting with disk height loss, and sometimes associated with disk herniation or calcification. These changes in turn can result in increased segment motion, compensatory osteophytes, buckling of ligamentum, and facet arthrosis, all of which can cause neural impingement.

 

3. The clinical presentation of spondylosis can be manifested as axial neck pain, radiculopathy, and/or myelopathy.



II. Axial Neck Pain

A. Evaluation

 

1. History and physical examination

 

a. Symptoms are typically episodic, with the acute pain generally improving over days to weeks.

 

b. Symptoms are often exacerbated with range of motion (particularly extension).

 

c. Occipital headaches are common.

 

d. Physical examination should assess active flexion, extension, lateral flexion, and rotation of neck.

 

e. Thorough neurologic examination with provocative tests should be performed to rule out radiculopathy or myelopathy.

 

2. Imaging studies

 

a. Indications for radiographs

 

i. History of trauma

 

ii. Prolonged duration of symptoms (>1 month)

 

iii. Presence of constitutional symptoms, known systemic disease (cancer or inflammatory arthritis)

 

b. Radiculopathy or myelopathy

 

c. Imaging findings

 

i. AP radiographs—Degenerative changes in the uncovertebral joints.

 

ii. Lateral radiographs—For overall alignment (lordosis, kyphosis), disk-space narrowing, vertebral body osteophytes, and listheses.

 

iii. Oblique radiographs—Presence of neuroforaminal stenosis or facet arthrosis.

 

iv. Flexion-extension views—Indicated if there is a history of instability or trauma, or to investigate the presence of postoperative pseudarthrosis.

 

v. Open-mouth odontoid view—Odontoid fractures as well as the presence of atlantoaxial arthritis.

 

vi. CT scans with appropriate sagittal and coronal reconstructions delineate the bony anatomy associated with fractures, foraminal stenosis, facet arthritis, and the presence of ossification of the posterior longitudinal ligament (OPLL).

 

vii. MRI is useful for diagnosis of infections and neoplasms.

 

viii. MRI or CT myelography is used to rule out neural compression.

 

3. Differential diagnosis of isolated axial neck pain

 

a. The differential diagnosis includes fractures, dislocations, inflammatory arthritides (rheumatoid arthritis, ankylosing spondylitis), infections (diskitis, osteomyelitis, epidural abscess), tumors (intradural, extradural), and nonspine sources.

 

b. These causes of neck pain should be ruled out before embarking on the treatment of cervical spondylosis.

 

B. Treatment

 

1. Nonsurgical treatment is favored for most patients with isolated axial neck pain due to cervical spondylosis.

 

2. Nonsteroidal anti-inflammatory drugs (NSAIDs) are favored over narcotic-based medication.

 

3. Isometric cervical muscle strengthening, heat/ice/massage, and short-term immobilization in a soft collar can be considered.

 

4. Surgical fusion for isolated axial neck pain is controversial. Favorable results have been reported with posterior arthrodesis in selected patients with atlantoaxial osteoarthrosis who fail nonsurgical treatment, demonstrate secondary C1-C2 instability, or have neurologic compromise.

 

C. Atlantoaxial osteoarthrosis

 

1. Frequently missed cause of axial neck pain

 

2. Patients typically older (in their 70s or older)

 

3. Pain is localized to the occipitocervical junction; rotation (to one side if the arthrosis is unilateral, or to both sides if bilateral) exacerbates the pain, but sagittal plane motion typically does not.



III. Cervical Radiculopathy

A. Pathoanatomy

 

1. Compression of the exiting nerve root as it enters the neuroforamen

 

a. Nuclear material arising from acute "soft" disk herniations can impinge the exiting nerve root posterolaterally at its takeoff from the spinal cord (

Figure 1) or intraforaminally as it traverses the neuroforamen.

 

b. Chronic disk degeneration with resultant disk height loss can lead to so-called "hard" disk pathology (

Figure 2) from either a combination of anular bulging without frank herniation or the formation of degenerative osteophytes that typically arise from the uncinate regions of the posterolateral vertebral body (uncovertebral osteophytes).

 

2. Disk height loss leading to subsequent foraminal root compression

 

3. Hypertrophy of the facet joints

 

4. Stimulation of the nerve root by chemical pain mediators

 

5. Herniated disk materials can incite the production of various inflammatory cytokines such as interleukin-1 (IL-1) and IL-6, substance P, brady-kinin, tumor necrosis factor α, and prostaglandins.

 

B. Evaluation

 

1. History and physical examination

 

a.

Patients frequently have unilateral neck pain that radiates ipsilaterally into the distribution of the affected root (

Table 1).

i. The most common levels of root involvement are C6 and C7.

 

ii. Less common levels of root involvement are C2, C3, and C4.

b.

Absence of radiating symptoms in a dermatomal distribution does not rule out the presence of symptomatic nerve root compression.

c.

Patients may also report upper trapezial and interscapular pain.

 

i.

A careful physical examination should be performed to identify the nerve root involved, with the caveat that crossover between myotomes and dermatomes may be present.

 

ii.

Cervical nerve roots exit above their correspondingly numbered pedicles (C6 root exits between C5 and C6); the exception is the C8 root, which exits above the T1.

 

[Figure 1. Axial T2-weighted MRI scan demonstrating a left posterolateral soft disk herniation with compression of the exiting root.]

[Figure 2. Images of a patient with an uncovertebral spur. A, Axial T2-weighted MRI scan demonstrating an uncovertebral spur, right greater than left. B, Axial postmyelogram CT scan confirms that the compressive entity in A is an uncovertebral spur rather than soft disk material. Note that the axial slice cuts obliquely through the disk space, through the foramen on the right versus the pedicle on the left. It can be difficult to differentiate soft versus hard disk pathology on MRI alone. Although myelography was used in this example, it is not routinely needed in a patient with a high-quality MRI if the purpose is to delineate hard versus soft disk pathology. A noncontrast CT scan can be used under those circumstances to complement information obtained on MRI.]

[Table 1. Common Cervical Radiculopathy Patterns]

 

iii.

Compressive lesions in the cervical spine tend to produce radiculopathy of the exiting nerve root. (Both posterolateral C5-C6 disk herniation and C5-C6 foraminal stenosis from an uncovertebral osteophyte usually lead to C6 radiculopathy.)

 

iv.

Large central to midlateral disk herniation or stenosis may affect the subjacent root.

d.

Sensory testing should include at least one function from the dorsal columns (joint position sense, light touch) and the spinothalamic tract (pain and temperature sensation).

e.

Upper motor neuron signs should be tested (Hoffman sign, inverted brachioradialis reflex, clonus, Babinski, and gait instability) to determine the presence of coexisting myelopathy or other neurologic disorder.

f.

Several provocative tests may elicit or reproduce symptoms of radiculopathy. One of the most sensitive is the Spurling maneuver.

i. The Spurling maneuver is performed by maximally extending and rotating the neck toward the involved side. This narrows the neuroforamen and may reproduce the symptoms.

 

ii. When positive, this test is particularly useful for differentiating cervical radiculopathy from other etiologies of upper extremity pain, such as peripheral nerve entrapment disorders, because the maneuver stresses only the structures within the cervical spine.

 

2. Differential diagnosis—Includes peripheral nerve entrapment syndromes (carpal or cubital tunnel syndromes); brachial plexus injury; Parson Turner syndrome; and tendinopathies of the shoulder, elbow, and wrist.

 

a. Selective cervical nerve root injections can be useful for confirming the source of symptoms if they improve for a period of time after the injection.

 

b. Electromyography and nerve conduction tests may help differentiate radiculopathy from peripheral entrapment disorders; however, they should never be the sole determinant for planning treatment because false-positive and false-negative electrodiagnostic studies are not uncommon.

 

c. Visceral disorders (coronary artery disease and cholecystitis causing referred pain to the upper extremity) should also be considered.

 

C. Nonsurgical treatment overview

 

1. The natural history of cervical radiculopathy is generally considered to be favorable.

 

2. Nonsurgical treatment is the initial treatment of choice in most situations, but controlled trials that compare the various nonsurgical regimens (such as physical therapy, modalities, traction, medications, manipulation, immobilization) with no treatment at all are lacking. It remains unclear whether nonsurgical treatment actually improves upon the natural history of the disorder or simply treats the symptoms as the disorder runs its course.

 

D. Nonsurgical treatment regimens

 

1. Cervical collar

 

a. Immobilization by means of a cervical collar is thought to diminish inflammation around an irritated nerve root and may relieve muscle spasm.

 

b. The efficacy of collars in limiting the duration or severity of radiculopathy has not been demonstrated.

 

c. Although the short-term use of collars may be beneficial, prolonged immobilization (longer than 1 to 2 weeks) should be avoided to prevent atrophy of the cervical musculature.

 

2. Traction

 

a. Home traction is of unproven benefit in nonsurgical treatment.

 

b. Traction should be avoided in myelopathic patients to prevent stretching of a compromised spinal cord over a compressive lesion.

 

3. Medications

 

a. NSAIDs—Although equivalent evidence is not available for cervical radiculopathy, meta-analysis suggests that NSAIDs are effective for acute low back pain.

 

i. Patients on long-term NSAID therapy should be monitored for potential liver, kidney, and gastrointestinal toxicity.

 

ii. Selective cyclooxygenase-2 (COX-2) inhibitors reduce the incidence of gastrointestinal side effects, but in controlled trials of osteoarthritis, they do not appear to be any more efficacious than nonselective NSAIDs.

 

b. Narcotic analgesics

 

i. Narcotics are necessary for symptom relief in the early, severe stages.

 

ii. Narcotics are not ideal for long-term management of most patients because of their addictive potential.

 

iii. Muscle relaxants provide symptomatic relief while decreasing narcotic requirements and are typically used for short periods of time.

 

c. Antidepressants and anticonvulsants are used in the treatment of chronic neuropathic pain syndromes.

 

d. Oral corticosteroids

 

i. These drugs are commonly prescribed because they anecdotally appear to be effective in diminishing acute radicular pain, but their ability to favorably alter the natural history of cervical radiculopathy over the long term has not been demonstrated.

 

ii. Patients should be counseled carefully as to the risks and benefits of corticosteroids because rare but significant complications such as infections, hyperglycemia, and osteonecrosis can occur.

 

4. Physical therapy

 

a.

Physical therapy has not been shown to alter the natural history of cervical radiculopathy.

b.

After an initial period of short-term rest and/or immobilization, a graduated program of physical therapy is commonly prescribed for symptomatic relief.

c.

Massage and modalities such as heat, ice, electrical stimulation, and ultrasound have not been proven to be beneficial in the long term.

 

[

Table 2. Common Surgical Approaches for Cervical Radiculopathy]

d.

Postural education, ergonomics, and lifestyle modifications may be beneficial.

e.

Isometric exercises to strengthen the cervical musculature are instituted as acute pain resolves.

f.

Aerobic conditioning may be helpful in relieving symptoms.

 

5. Cervical manipulation

 

a. The efficacy of cervical manipulation has not been established.

 

b. For neck pain and cervicogenic headaches, cervical manipulation probably provides short-term benefits with a complication rate between 5 and 10 per 10 million manipulations.

 

6. Cervical steroid injections

 

a. These injections are commonly used in the nonsurgical management of radiculopathy, both lumbar and cervical.

 

i. Injections allow specific targeting of problematic root(s) and the dorsal root ganglion, resulting in a greater local concentration of steroid at the desired location.

 

ii. They provide diagnostic information by blocking the pain associated with a symptomatic root. Such information may be used in surgical planning or prognostication.

 

b. Complications of cervical injections are rare but include dural puncture, meningitis, epidural abscess, intraocular hemorrhage, adreno-cortical suppression, epidural hematoma, and root or spinal cord injury.

 

E. Surgical treatment overview

 

1. Indications include severe or progressive neurologic deficit (weakness or numbness) or significant pain that fails to respond to nonsurgical treatment.

 

2. Cervical radiculopathy may be addressed through either an anterior or posterior surgical approach, depending on pathology (Table 2).

 

F. Surgical procedures

 

1. Anterior cervical decompression and fusion (ACDF)

 

a. Advantages

 

i. ACDF allows direct removal of most lesions causing cervical radiculopathy (herniated disks, uncovertebral spurs) without neural retraction.

 

ii. Placement of an anterior bone graft in the disk space opens up the neuroforamen and thereby provides indirect decompression of the nerve root.

 

iii. Associated fusion may also help to improve any component of neck pain arising from disk degeneration and spondylosis.

 

iv. ACDF is associated with extremely low rates of infection or wound complications.

 

v. Anterior incisions tend to be cosmetically preferable, especially when the incision is placed in creases of the neck, where it heals with a virtually imperceptible scar.

 

vi. ACDF requires little muscle dissection and is generally associated with little perioperative pain.

 

b. Disadvantages

 

i. ACDF has a potential for pseudarthrosis and other graft-related complications.

 

ii. Factors impacting the pseudarthrosis rate include patient variables (smoking), graft type (autograft versus allograft), number of levels operated on, and plating.

 

iii. Conflicting factors make comparisons among studies impossible. Plated ACDF with allograft

 

[

Figure 3. AP (A) and lateral (B) radiographs of a patient after cervical disk replacement for soft disk herniation.]

   is presently a popular option for one or two levels to avoid donor-site morbidity and because results using allograft have been acceptable. Three-level fusion rates have historically been thought of as suboptimal, but this may not hold true in the modern era of anterior cervical plating. Poor fusion rates have been reported with more than two levels, even with plated autograft; a corpectomy construct is recommended instead. Plating is popular when performing more than a single level ACDF or if allograft is used at one or more levels.

 

iv. Persistent speech and swallowing complications are associated with anterior exposure and retraction of the esophagus and laryngeal nerve; estimates range from 2% to 5%.

 

c. Performing anterior decompressions without fusion is an option; however, this has recently fallen out of favor because of the potential for local kyphosis and worsening neck pain.

 

2. Cervical disk replacement

 

a. Overview

 

i. Cervical disk replacement is an emerging technology that may be available in the near future (Figure 3).

 

ii. Several trials sponsored by the US Food and Drug Administration have been completed or are currently ongoing.

 

iii. The surgical approach and method of neural decompression are essentially identical to that of ACDF; the artificial disk is placed into the decompressed disk space rather than bone supplemented with plates and screws.

 

b. Advantages

 

i. Cervical disk replacement maintains motion and avoids nonunions and plate and screw complications such as backout, esophageal erosion, and periplate ossification.

 

ii. One major long-term benefit may be the asyet-unproven potential for reducing the incidence of adjacent segment degeneration; however, the true efficacy of cervical disk replacement can be determined only by long-term studies.

 

c. Current available evidence suggests that symptomatic adjacent segment disease occurs at a rate of about 3% per year regardless of whether the index operation for radiculopathy was anterior diskectomy with fusion, anterior diskectomy without fusion, or posterior foraminotomy without fusion.

 

d. Preliminary results using a variety of different prostheses have been favorable, reflecting the fact that neural decompression is the cornerstone of early clinical improvement.

 

3. Posterior decompression

 

a. Posterior laminoforaminotomy can be used to decompress the nerve root without significantly destabilizing the spine in patients with anterolateral disk herniation or foraminal stenosis.

 

i. A compressive lesion ideally should be located such that unroofing the foramen adequately decompresses the root.

 

ii. The offending disk herniation or anterior osteophyte can be (but does not need to be) removed as long as the compressed span of nerve root is freed up posteriorly.

 

iii. If disk herniation is to be removed posteriorly, the superior pedicle of the inferior vertebra may need to be drilled away to allow safe access to the disk space without undue neural retraction.

 

b. Advantages

 

i. Minimal patient morbidity

 

ii. Avoids fusion and its attendant complications

 

iii. Reported success rate of up to 91.5%

 

c. Disadvantages

 

i. Possibility for incomplete decompression in the setting of anterior compressive lesions

 

ii. Inability to restore disk and foraminal height at the diseased level

 

iii. Potential for deterioration of results with time if the degenerative process continues in the absence of a fusion

 

4. Indications for anterior versus posterior approach

 

a. Few, if any, absolute indications exist for decompressing the nerve root either anteriorly or posteriorly.

 

b. Scar tissue—If the patient had prior surgery from one approach, it may be advantageous to perform surgery from the opposite approach to avoid working through scar tissue. For example, a posterior foraminotomy could be performed in patients with persistent radiculopathy after ACDF; a revision anterior procedure can be performed with excellent results and avoids any morbidity associated with a posterior approach.

 

G. Outcomes of surgical treatment

 

1. Very high success rates

 

2. Relief of arm pain, as well as improvements in motor and sensory function, are typically in the 80% to 90% range.

 

3. In failed nonsurgical treatment, surgery can permanently alter the natural history of symptoms arising from the involved motion segment.



IV. Cervical Myelopathy

A. Overview

 

1. Cervical myelopathy describes a constellation of symptoms and signs arising from cervical cord compression.

 

2. Presentation can be quite subtle in its early manifestations.

 

3. Diagnosis may easily be missed or wrongly attributed to "normal" aging.

 

4. The natural history is typically one of stable periods punctuated by unpredictable stepwise progression.

 

5. Early recognition and treatment, before the onset of irreversible spinal cord damage, is essential for optimal outcomes.

 

B. Clinical presentation

 

1. Upper extremity

 

a. Generalized feeling of clumsiness of the arms and hands; "dropping things"

 

b. Inability to manipulate fine objects such as coins or buttons

 

c. Trouble with handwriting

 

d. Diffuse (typically nondermatomal) numbness

 

2. Lower extremity

 

a. Gait instability—Patients report a sense of imbalance and "bumping into walls" when walking.

 

b. Patients with severe cord compression may also report the Lhermitte sign: electric shock-like sensations that radiate either down the spine or into the extremities with certain offending positions of the neck.

 

3. Symptoms that occur late or not at all

 

a. Subjective weakness

 

b. Bowel and bladder symptoms

 

c. Many patients deny any loss of motor strength.

 

d. Despite advanced degrees of spondylosis, no neck pain

 

e. Many patients have no radicular symptoms or signs.

 

f. A high degree of suspicion may be necessary to make the diagnosis of myelopathy when the disease is in its most treatable, early stages.

 

4. Physical examination

 

a. Severe weakness of the major muscle groups in the upper or lower extremities is relatively uncommon.

 

b. Dorsal column (proprioceptive) dysfunction occurs with advanced disease and carries a poor prognosis.

 

c. Hyperreflexia may be present in the upper and/or lower extremities and is suggestive of spinal cord compression.

 

d. Patients with concomitant myelopathy and peripheral nerve disease from conditions such as diabetes, peripheral neuropathy, or severe multilevel cervical foraminal stenosis can have diminished or absent reflexes.

 

e. Patients with cervical myelopathy who have coexisting lumbar stenosis may exhibit brisk upper extremity reflexes consistent with upper motor neuron findings yet diminished lower extremity reflexes because of the root level compression in the lumbar spine.

 

C. Differential diagnosis

 

1. Spondylosis, or degenerative changes, producing the condition known as cervical spondylotic myelopathy (CSM), is the most common cause of cervical myelopathy in patients older than age 50 years.

 

a. Anterior structures (such as bulging, ossified, or herniated disks) as well as osteophytic anterior spurs are the usual cause of cord compression in CSM.

 

b. Less commonly, conditions involving the posterior structures, such as ligamentum flavum hypertrophy or, rarely, ossification of the ligamentum flavum, may contribute.

 

c. Degenerative spondylolisthesis can also exacerbate or cause compression.

 

d. CSM commonly arises in the setting of a congenitally narrowed cervical canal. CSM often does not become symptomatic until the later decades of life because the cord may have sufficient space to escape compression until a threshold amount of space-occupying degenerative changes accumulate.

 

2. Less commonly, other causes of cervical cord compression, such as epidural abscess, tumor, and trauma, can result in cervical myelopathy. These cases usually present somewhat differently, with pain, constitutional symptoms, or history of injury in addition to myelopathic complaints.

 

3. Kyphosis (primary or postlaminectomy) is another less common cause.

 

4. A broad differential diagnosis should be considered, including nonspinal disorders such as stroke, movement disorders, and multiple sclerosis.

 

D. Imaging evaluation

 

1. MRI

 

a. Both MRI and CT myelography are necessary to confirm spinal cord compression.

 

b. MRI is noninvasive and provides adequate imaging characteristics in most patients.

 

c. Signal changes within the cord may be demonstrated on MRI and suggest severe compression.

 

d. A compression ratio of <0.4 (measured as the ratio of the smallest sagittal cord diameter to the largest transverse cord diameter at the same level) is another finding carrying a poor prognosis. Conversely, expansion of the compression ratio to >0.4 postoperatively correlates with clinical recovery.

 

2. CT myelography

 

a. Consider CT myelography if MRI scans cannot be obtained for medical reasons (eg, cardiac pacemakers, aneurysm clips, or severe claustrophobia), or if metal or scar from prior cervical surgery precludes adequate visualization on MRI because of artifact.

 

b. CT myelography may help diagnose the presence of OPLL, which may not be obvious on MRI or plain radiographs but can have a profound effect on surgical approach.

 

E. Treatment

 

1. CSM is typically progressive and is considered a surgical disorder; cord compression can cause myelopathy either by an ischemic effect secondary to compression of the anterior spinal artery or by a direct mechanical effect on cord function.

 

2. Surgical management has been shown to improve functional outcomes, pain, and neurologic status and is the treatment of choice.

 

3. Early intervention, before permanent, destructive changes occur in the spinal cord, improves the prognosis.

 

4. If nonsurgical care is elected, careful and frequent follow-up is mandatory. Firm orthoses, anti-inflammatory medications, isometric exercises, and epidural steroids can be considered.

 

F. Overview of surgical treatment options

 

1. Considerable debate exists regarding the optimal surgical approach. Options include laminectomy with or without fusion, ACDF, and laminoplasty.

 

2. No one procedure is clearly favorable in all circumstances, but the following considerations may favor one approach over another:

 

a. Number of stenotic levels present

 

b. Patient factors, such as comorbidities

 

c. Desire to either limit or preserve motion

 

G. Laminectomy without fusion

 

1. Effective in stable spines, as long as facets are mostly preserved

 

2. Postlaminectomy kyphosis can occur after laminectomy, with estimates ranging from 11% to 47%. Although this complication can lead to potential recurrent myelopathy if the cord becomes draped and compressed over the kyphos, the incidence of clinically apparent neurologic problems resulting from this complication is unclear.

 

H. Laminectomy with fusion

 

1. This procedure avoids the pitfalls of laminectomy alone.

 

2. Potential benefits

 

a. Improvement of spondylotic neck pain and prevention of postlaminectomy kyphosis

 

b. Preexisting kyphosis can be improved after laminectomy by positioning the neck in extension before securing the instrumentation; for higher degrees of kyphosis, an anterior-posterior approach is generally recommended.

 

3. Despite advantages over laminectomy alone, laminectomy with fusion may be outperformed by alternative procedures.

 

4. When fusion is not necessary, laminoplasty may be a better choice.

 

I. Anterior cervical decompression and fusion

 

1. ACDF can directly decompress structures most commonly responsible for cord compression, such as herniated disks, spondylotic bars, and OPLL.

 

2. ACDF also can directly relieve neural compression resulting from kyphosis by removing the vertebral bodies over which the cord may be draped.

 

3. The procedure helps to relieve spondylotic neck pain, can correct and improve kyphosis, immobilizes and therefore protects the segment of decompressed cord, and prevents recurrent disease over the fused segments.

 

4. Excellent neurologic recovery rates have been reported with anterior surgery for myelopathy.

 

5. For myelopathy arising from one or two disk spaces, a single- or two-level ACDF (or a single-level corpectomy for two motion-segment disease) is the treatment of choice for most patients. For patients with stenosis at three or more disk segments, however, the supremacy of an anterior approach is not as clear-cut.

 

J. Multilevel anterior corpectomy and fusion

 

1. Pseudarthrosis rates after multilevel anterior corpectomy and fusion range from 11% to 40%.

 

2. Less frequent but more troublesome is graft dislodgment, reported to occur in 7% to 20% of patients, which can be associated with neurologic compromise, esophageal injury, and even airway obstruction leading to death.

 

3. Nonplated corpectomies with long strut grafts have shown good clinical results but require cumbersome rigid external immobilization and have been associated with the morbidity of autologous fibular harvest.

 

4. Supplemental posterior fixation and fusion may be prudent if a long strut graft is necessary anteriorly to provide better stability and reduce the incidence of graft kickout and pseudarthrosis.

 

5. All anterior fusion operations carry relatively small but real risks intrinsic to the anterior approach, such as permanent speech and swallowing disturbance, airway obstruction, esophageal injury, and vertebral artery injury; risks are probably higher for multilevel reconstructions than for a single- or two-level ACDF because of longer surgical times and number of levels exposed.

 

K. Laminoplasty

 

1. Overview

 

a. Laminoplasty was initially used in Japan but is gaining wider acceptance in North America. This technique is designed to achieve multilevel posterior cord decompression while avoiding the major problem associated with laminectomy, postlaminectomy kyphosis.

 

b. Common to all variations of the procedure is the creation of a hinge at the junction of the lateral mass and lamina by thinning the dorsal cortex but not cutting through the ventral cortex completely, allowing the creation of green-stick fractures.

 

c. A C3 through C7 procedure is performed in most cases.

 

2. Surgical techniques

 

a.

Open door and French door are the most common types of laminoplasty. Differences between these techniques are listed in

Table 3.

 

[Table 3. Laminoplasty Techniques]

b.

Opening the laminoplasty increases the space available for the spinal cord, which drifts away from compressive lesions into the space created; it can then be held patent with bone (autologous spinous process or rib allograft), sutures, suture-anchors, or specially designed plates.

 

3. Laminoplasty has several distinct advantages over anterior surgery in the properly selected patient.

 

a. Laminoplasty is generally a safer and technically easier operation to perform than multilevel anterior corpectomy, particularly in patients with severe stenosis or OPLL that requires resection, because an indirect decompression is performed.

 

b. Laminoplasty is a motion-preserving procedure.

 

i. No fusion is required, so all fusion-related complications are eliminated.

 

ii. Pseudarthrosis is avoided in patients at high risk for this complication, such as patients with diabetes, elderly patients, and chronic steroid users.

 

c. Laminoplasty does not preclude a later anterior procedure. If the patient has persistent stenosis after laminoplasty, focal anterior decompressions can be subsequently performed at needed levels.

 

4. Complications

 

a. Postoperative segmental root level palsy

 

i. This complication occurs in 5% to 12% of patients.

 

ii. Although other roots also can be affected, the palsy most commonly affects the C5 root, resulting in deltoid and biceps weakness.

 

iii. Palsies tend to be motor-dominant, although sensory dysfunction and radicular pain also can occur.

 

iv. Palsy can occur at any time postoperatively, from immediately to 20 days later, complicating what otherwise appeared to be a successful spinal cord decompression.

 

b. Neck pain

 

i. Because no arthrodesis is performed, laminoplasty should not be used to treat painful spondylosis.

 

ii. Controversy remains as to whether neck pain associated with laminoplasty reflects new-onset postoperative symptoms or simply persistence of preoperative spondylotic pain.

 

c. Loss of motion

 

i. Motion loss may be related to facet joint injury with spontaneous stiffening or fusion, or to alterations in tissue and muscle elasticity after posterior surgical exposure.

 

ii. Prolonged postoperative immobilization can contribute to the problem.

 

iii. Placing bone graft along the hinge side to assist in healing of the hinge may lead to undesired intersegmental fusion or stiffening.

 

iv. Motion loss can be limited by using short-term postoperative immobilization and avoiding bone grafting on the hinge side.

 

5. Considerations in the patient with preoperative kyphosis

 

a. Drift-back, which occurs reliably in a lordotic or neutral cervical spine, may not occur in the setting of significant kyphosis.

 

b. Absence of lordosis is not an absolute contraindication to laminoplasty.

 

i. In kyphotic patients who have compressive lesions arising posteriorly, laminoplasty may also achieve a direct decompressive effect despite kyphosis.

 

ii. In kyphotic patients with extremely tight cervical stenosis, laminoplasty can be considered as a first-stage operation, with subsequent anterior surgery performed if necessary.

 

L. Combined anterior and posterior surgery

 

1. Combined anterior and posterior surgery is strongly recommended in patients with postlaminectomy kyphosis.

 

2. When multilevel corpectomy is performed to decompress the cord, an extremely unstable biomechanical environment results because of the preexisting laminectomy: The right and left sides of the spine become disconnected from each other.

 

3. Supplemental posterior fixation is recommended to improve construct stability.

 

4. Supplemental posterior fixation and fusion should be considered in patients with significant kyphosis requiring multilevel anterior decompression.

 

M. Ossification of the posterior longitudinal ligament

 

1. Overview/epidemiology

 

a. OPLL is a potential cause of cervical myelopathy.

 

b. OPLL is common in, but not limited to, the Asian population.

 

c. The cause of OPLL remains unclear but is most likely multifactorial and related to genetic, hormonal, and environmental influences. Factors implicated include diabetes, obesity, a high-salt and low-meat diet, poor calcium absorption, mechanical stress on the posterior longitudinal ligament, and even sleep habits.

 

2. Patient presentation—Patients may be completely asymptomatic or have severe myelopathy.

 

3. Patient considerations

 

a. The same general guidelines that apply to the choice of approach in CSM apply to OPLL.

 

b. In patients with severe OPLL, a posterior approach may be preferable and safer, regardless of the number of stenotic levels involved.

 

4. Treatment—As with CSM, the treatment of myelopathy due to OPLL is typically surgical.

 

a. Direct resection via an anterior approach—One way to avoid troublesome dural tears is to allow the adherent OPLL to float anteriorly after corpectomy without necessarily removing it.

 

b. Interbody fusion without decompression

 

i. This technique, which has been reported to have surprisingly good results, is suggested for the patient with dynamic myelopathic symptoms. By immobilizing and fusing the stenotic areas, repeated trauma to the cord by the ossified mass can be avoided.

 

ii. A posterior approach with a laminoplasty also can be used to achieve cord decompression without resection of OPLL.

 

iii. Posterior approaches, such as laminoplasty and laminectomy, that do not resect the OPLL introduce the potential for postoperative OPLL growth.

 

5. Complications

 

a. Anterior approaches with floating of the OPLL or complete excision have been touted to avoid postoperative growth of OPLL.

 

b. Posterior procedures, in contrast, are associated with a tendency toward radiographic enlargement of OPLL postoperatively.



Top Testing Facts

Cervical Radiculopathy

1. Cervical nerve roots exist above their corresponding numbered pedicles. (C6 exists between C5 and C6.)

 

2. Nonsurgical treatment should be attempted for the vast majority of patients with cervical radiculopathy. Many forms of nonsurgical treatment relieve the pain but may not alter the natural history of the disease.

 

3. Surgical management provides excellent and predictable outcomes in patients with progressive neurologic dysfunction or failure to improve despite time and nonsurgical treatment. Either an anterior or a posterior approach can be selected in the appropriate circumstances, understanding that neither is perfect and each carries its own set of pros and cons.

 

4. Complications associated with ACDF include persistent speech and swallowing problems.

 

Cervical Myelopathy

1. Cervical myelopathy is typically a surgical disorder.

 

2. Early treatment, before the onset of permanent cord injury, is recommended.

 

3. An anterior approach is indicated in patients with myelopathy arising from one or two disk segments.

 

4. Laminoplasty is indicated in patients with multilevel involvement (three or more disk spaces).

 

5. A combined anterior-posterior approach is indicated in patients with multilevel stenosis and kyphosis, or those with postlaminectomy kyphosis.

 

6. The surgical procedure chosen must be tailored to the patient's specific pattern of stenosis, comorbidities, and symptoms. Strict adherence to a blind algorithmic protocol should be avoided.



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