Cervical Herniated Nucleus Pulposus and Stenosis

Abstract

The purpose of this chapter is to assess the scientific rigor of the literature involving MIS approaches to the cervical spine, the overall quality of the reporting, indications for various procedures, complications associated with each approach, and the extent to which the outcomes can relate to clinical practice. Although the techniques and equipment were at first cumbersome, MIS procedures have become a reality with technological developments and improved skills. In this chapter, we focus on minimally invasive cervical procedures. We organize the topic by approach (anterior and posterior), and for each, we evaluate the surgeries used to treat cervical herniations and stenosis.

Appendices

Quiz Questions

• 1. Which of the following best describes the function of a proteoglycan?

  • (a) Adjust the amount of water in the tissue by repelling each other and by using their capacity to lengthen and contract their multiple negatively charged appendages.

  • (b) It provides the matrix that sustains the body’s structure.

  • (c) They produce the energy currency of the cell, through respiration and through the regulation of cellular metabolism.

  • (d) Soft collagenous tissue which connects bone to bone, and tendons connect muscles to bone.

    Basic Science Question: Hyaluronan (HA), chondroitin and keratan sulphates (CS, KS), collagen vary in different amounts within the annulus fibrosus and nucleus pulposus of the human cervical, thoracic and lumbar intervertebral discs with varying regional differences and age-related trends. The function of proteoglycans are to adjust the amount of water in the tissue by repelling each other and by using their capacity to lengthen and contract their multiple negatively charged appendages.

• 2. Which is not an indication for single-stage anterior and posterior release for correction of cervical kyphotic deformity?

  • (a) Fixed cervical kyphosis involving a fixed anterior and posterior column over several segments

  • (b) Surgeons experienced in vertebral artery mobilization

  • (c) Surgeons experienced in anterior osteotomy procedures for a fixed cervical deformity

  • (d) Patients with ventral based pathology and a flexible mobile cervical spine

    When faced with the prospect of addressing a cervical kyphotic deformity with the main distinction being between a flexible and rigid deformity leading to the selection of either anterior alone, posterior alone, combined anteroposterior or posterioranterior-posterior approaches are based mainly on the presence or absence of ankyloses and its location. Recent anterior osteotomy techniques can allow for correction of complex cervical fixed deformity that when appropriately combined with posterior release can be utilized to treat fixed cervical deformity through a single staged 360° approach. However this would not be indicated in a patient with ventral based pathology and a flexible mobile cervical spine, as this could be addressed through an anterior only approach. All other instances would be potential candidates for single-stage anterior and posterior release for correction of cervical kyphotic deformity.

• 3. Which is not a consideration for approaches when considering cervical surgery?

  • (a) Location of the herniation

  • (b) Size of the herniation

  • (c) Number of levels involved

  • (d) Patient gender

    When undergoing cervical surgery the approach may be dependent upon the location of the herniation, the size of the pathology, and the numbers of levels involved. However patient gender would not affect the approach.

• 4. During the anterior foraminotomy, which structure is protecting the vertebral artery?

  • (a) Posterior longitudinal ligament

  • (b) Annulus fibrosus

  • (c) Uncinate process

  • (d) Nucleus pulposus

    As seen in the section above the Uncinate Process is directly protecting the vertebral artery. This is carefully flicked off during the approach, exposing the vertebral artery directly posterior to its bony cortical edge.

• 5. During a cervical arthroplasty, what provides long-term implant fixation?

  • (a) Bony ongrowth

  • (b) Bony ingrowth

  • (c) The implant keel

  • (d) Implant screw fixation

    During arthroplasty immediate fixation is provided by implant hardware such as spikes or keels, long term fixation is afforded by the Bony Ingrowth into the vertebral endplates.

• 6. During percutaneous transfacet fixation, which trajectory is associated with a higher incidence of facet fractures and an increased proximity and risk to the vertebral artery and exiting nerves?

  • (a) A lateral trajectory near the lower third of the lateral mass

  • (b) A midpoint trajectory near the junction of the middle and upper third of the lateral mass

  • (c) A lateral trajectory near the upper third of lateral mass

  • (d) A midpoint trajectory near lateral third of the lateral mass

    While performing percutaneous transfacet fusion a midpont trajectory that is near the junction of the middle and upper third of the lateral mass is associated with a higher incidence of facet fractures and places the drill in closer proximity to the vertebral artery and exiting nerve root.

• 7. Which of the following is not an indication for percutaneous posterior cervical transfacet screws?

  • (a) Lateral mass fractures

  • (b) Cervical stenosis

  • (c) Anchors for posterior fixation

  • (d) Reinforcing anterior fusion constructs

    All answers are appropriate indications for posterior cervical transfacet screw fixation with the exception of Cervical Stenosis.

• 8. Which of the following is not an indication for skip laminectomy?

  • (a) Rheumatoid arthritis

  • (b) Congenital stenosis

  • (c) Calcification of yellow ligament (CYL)

  • (d) Multisegmental cervical spondylotic myelopathy

  • (e) Segmental or localized ossification of posterior longitudinal ligament (OPLL)

    A skip laminectomy is a laminectomy performed where certain lamina are removed and intervening lamina are preserved to allow for a recreation of the supraspinous ligament and prevent long term cervical kyphosis. This scenario could result in patients with congenital stenosis, calcification of the yellow ligament and multisegmental CSM. This would not be indicated in patients with Rheumatoid Arthritis.

• 9. Which of the following is an indication for microscopic tubular-assisted posterior laminoforaminotomy?

  • (a) Multiple-level pathology

  • (b) Foraminal soft disc herniations

  • (c) Osteoarthritis

  • (d) Tumor

    Of the pathologies listed the only true indication for a microscopic tubular posterior laminoforaminotomy is Foraminal soft disc hernations. All other pathologies listed would need to be addressed with other procedures all together.

• 10. Which of the following is not an indication for cervical hybrid arthroplasty?

  • (a) Unilateral or bilateral multilevel pathology

  • (b) Foraminal soft disc multilevel herniations

  • (c) Significant facet joint hypertrophy at the arthroplasty level

  • (d) Young patient age with multiple-level contiguous disc herniations involving contiguous nerve root levels

    Cervical hybrid arthroplasty: A combination of an artificial disc replacment and a cervical fusion would be an option for all pathologies listed with the exception of a patient with significant facet joint hypertropy at the level of the arthroplasty. A patient with significant facet joint arthropathy would not be a candidate for an artificial disc replacement.

• 11. Which of the following is not a relative contraindication to performing an anterior foraminotomy?

  • (a) Posterolateral disc fragments

  • (b) Extensive ossification of the posterior longitudinal ligament (OPLL) with diffuse osteophytic spinal canal stenosis

  • (c) Myelopathy

  • (d) Vascular abnormalities (e.g., tortuous vertebral artery)

    An anterior foraminotomy would be indicated for patients who have pathology which can be addressed from an anterior portal , however patients with certain pathology pose a relative contraindication. Examples of this include patients with a kinky or tortuous vertebral artery, extensive OPLL and in myelopathic patients. Therefore a patient with a posterolateral disc fragment would not be contraindicated with this approach.

• 12. What structure is most at risk for injury if the lateral wall of middle aspect of the cervical 4 vertebral body is inadvertently penetrated during lateral drilling of a cervical 4 corpectomy?

  • (a) Cervical plexus

  • (b) C4 nerve root

  • (c) Internal carotid artery

  • (d) Vertebral artery

  • (e) C5 nerve root

  The vertebral foramen of C3, C4, C5, and C6 can tether the vertebral artery along the lateral aspect of the vertebral body of C6 which would make it vulnerable to a drill, which has migrated too far laterally. The C4 nerve root passes over the C4 pedicle and is not at risk. The C5 nerve root passes over the C5 pedicle but would be posterior to the vertebral artery and, while at risk, is not the most vulnerable structure as it would be most vulnerable along the posterior-inferior corner. The carotid artery and vagus nerve are within the carotid sheath and clear of injury at this level. The cervical plexus is formed by the communication of the anterior divisions of C1–C4 and lies under the sternocleidomastoid, so it is not at risk at the midlateral corpectomy level.

• 13. A 62-year-old man with severe multilevel cervical stenosis undergoes a complex four-level anterior cervical discectomy and fusion at C2–C6 with autogenous iliac crest bone graft and instrumentation. Surgical time was approximately 5 hours, and estimated blood loss was 600 mL. Neuromonitoring was stable throughout the procedure. The patient’s history is significant for smoking and hemodialysis every other day. Consideration for the most appropriate postoperative management for this patient should include:

  • (a) Administration of IV steroids every 8 hours and placement of a soft cervical collar for 24 hours

  • (b) Standard postoperative orders with the inclusion of frequent neurologic evaluations for the first 24 hours

  • (c) Maintaining intubation for up to 24–48 hours

  • (d) Administration of powdered antibiotic in the wound and placement of a hard collar

  • (e) Placement of both deep and superficial surgical drains prior to wound closure

  Following multiple-level anterior cervical surgery, surgeons must be proactive to decrease the potential for airway collapse, which can be a catastrophic event necessitating emergent intubation. This question presents a patient who has undergone a multilevel surgery, which was complex, and necessitated prolonged intubation, which coupled with prolonged soft tissue retraction in an elderly patient with smoking as preexisting comorbidities has predisposed this patient to potential postoperative airway collapse. Sagi and associates reported that variables statistically associated with an airway complication (P < 0.05) were exposing more than three vertebral bodies; a blood loss >300 mL; exposures involving C2, C3, or C4; and an operative time > 5 hours. A history of myelopathy, spinal cord injury, pulmonary problems, smoking, anesthetic risk factors, and the absence of a drain did not correlate with an airway complication [60].

• 14. One potential theory of nerve root injury, following posterior cervical decompression for stenosis myelopathy, is thought to be tethering of the nerve root with dorsal migration of the spinal cord. What is the most common radicular pattern seen in this circumstance?

  • (a) Motor-dominant radiculopathy with weakness of the triceps

  • (b) Sensory-dominant radiculopathy with pain in the lateral forearm

  • (c) Motor-dominant radiculopathy with weakness of the deltoid

  • (d) Sensory-dominant radiculopathy with pain in the lateral shoulder

  • (e) Motor-dominant radiculopathy with weakness of the finger extensors

  Dai et al. reviewed 287 consecutive patients with cervical compression myelopathy treated by multilevel cervical laminectomy and identified 37 patients (12.9%) with postoperative radiculopathy. Radiculopathy was observed from 4 hours to 6 days after surgery. The most frequent patterns of paralysis were C(5) and C(6) root involvements of the motor-dominant type. So the answer is motor-dominant radiculopathy with weakness of the deltoid. All patients showed complete recovery in 2 weeks to 3 years (average, 5.4 months) [61].

• 15. Independent predictors of degenerative cervical myelopathy development (DCM) include radiculopathy and electrophysiological dysfunction of cervical cord. Which other parameter has been found to be significant predictors for development of DCM?

  • (a) Lhermitte’s phenomenon

  • (b) Cross-sectional area (CSA) ≤ 70 mm²

  • (c) Spastic paresis of lower extremity, spastic gate

  • (d) Urinary urgency, frequency, or incontinence

  • (e) Compression ratio (CR) ≤ 0.2

  The establishment of MRI criteria for degenerative cervical cord compression is essential for reliable and reproducible diagnosis of DCM. The presence of impingement (i.e., focal change of contour) and/or CR < 0.4 as MRI criteria for cervical cord compression has been demonstrated to be a predictor for progression into DCM. Multivariate analysis showed that radiculopathy, cross-sectional area (CSA) ≤ 70.1 mm², and compression ratio (CR) ≤ 0.4 were the only independent significant predictors for progression into symptomatic myelopathy. Therefore the answer is B [62].

Answers

• 1. a

• 2. d

• 3. d

• 4. c

• 5. b

• 6. b

• 7. b

• 8. a

• 9. b

• 10. c

• 11. a

• 12. d

• 13. c

• 14. c

• 15. b