Degenerative Disk Disease Workup

Updated: Mar 15, 2019
  • Author: Stephen Kishner, MD, MHA; Chief Editor: Jeffrey A Goldstein, MD  more...
  • Print
Workup

Laboratory Studies

Seronegative spondyloarthropathies (SNSAs) are common causes of back pain and should be excluded.

Order HLA-B27 (class 1 histocompatibility HLA) testing to assess for ankylosing spondylitis (AS), reactive arthritis (formerly called Reiter syndrome), psoriatic arthritis, and inflammatory bowel–associated arthritis. AS is an inflammatory disease of unknown etiology that affects an estimated 350,000 persons in the United States and 600,000 in Europe, primarily white males in the second through fourth decades of life. Worldwide, the prevalence is 0.9%. Genetic linkage to HLA-B27 has been established. In the United States, 0.1-0.2% of whites are estimated to have AS. HLA-B27 is extremely rare in African Americans.

Serum immunoglobulin A (IgA) is elevated in some patients.

Inflammatory causes of low back pain can be ruled out with tests for acute-phase reactants such as the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level. A complete blood count (CBC) should be obtained, including a platelet count.

Rheumatoid factor (RF) testing and antinuclear antibody (ANA) testing are good screening tools for autoimmune disorders.

In rare cases, it may be necessary to exclude gout and calcium pyrophosphate dihydrate deposition by checking serum uric acid and performing synovial fluid analysis to check for crystals.

Next:

Imaging Studies

The role of imaging studies in degenerative disk disease is to provide accurate morphologic information that can be combined with clinical symptoms to guide therapeutic decision making.

Magnetic resonance imaging

The first open magnetic resonance imaging (MRI) scanner was produced by Fonar in 1982. In 1996, Fonar introduced the Stand-Up MRI, a whole-body MRI scanner with the ability to scan patients standing, sitting, bending, or lying down. With its unique ability to scan patients in weightbearing postures, the Stand-Up MRI allows identification of pathologies that are undetected on conventional recumbent MRI scanners, such as lumbar degenerative disk disease with disk herniations. An additional benefit of the Stand-Up MRI is its spacious and nonclaustrophobic geometric design. Patients typically sit comfortably watching a 42-in. television throughout the scanning procedure

MRI can be used to differentiate between the nucleus and the anulus; hence, it allows delineation of contained and noncontained disk herniations. With this information, pathologic disks can be described as protruded disks, extruded disks, or migrated disks.

MRI can show anular tears and the posterior longitudinal ligament. Therefore, it can be used to classify herniations, from simple anular bulging to extruded and free-fragment disk herniations.

Vertebral bodies adjacent to degenerating disks undergo changes, which Modic described as type 1 and type 2 changes. Some hypothesize that trauma to the intervertebral disks releases chemical substances that increase the diffusion resistance through an autoimmune mechanism. As the diffusion coefficient increases, the endplate undergoes sclerosis and the adjacent bone marrow exhibits an inflammatory response (ie, as it is infiltrated by fibrovascular tissue).

These changes (Modic type 1) lead to diminished intensity on T1-weighted images and increased intensity on T2-weighted images. The inflammatory response destroys the marrow of the adjacent vertebral endplates, which is replaced by fat. These changes (Modic type 2) lead to increased signal intensity on T1-weighted images, and the same or increased intensity on T2-weighted images.

MRI is the most comprehensive imaging modality for providing accurate, reliable, and detailed anatomic information in degenerative disk disease. Heuck et al found that clinical information can change the final impression of the radiologist in as many as 25% of cases and should always be considered in reading and reporting MRI findings. [9]

Computed tomography

In the absence of MRI, computed tomography (CT) is accurate in diagnosing disk herniations because of the contrast between herniated disk material, perineural fat, and the adjacent posterolateral margins of the bony vertebrae. However, MRI remains the imaging modality of choice for diagnosing lateral herniations.

CT offers several advantages over MRI. Among these are lower cost, less stress for claustrophobic patients, and better detection of subtle bony changes (eg, spondylolysis, early degenerative changes of the facet joints). CT is also better for assessing bony integrity after fusion.

Gundry and Heithoff established the following criteria for CT diagnosis of disk herniation with associated neural impingement [10] :

  • First, the disk protrusion must be focal and asymmetric, often dorsolateral in position, directly underlying the nerve root traversing that disk
  • Second, nerve root compression and/or displacement should be demonstrable
  • Third, postimpingement swelling of the affected nerve root is often present caudal to the herniation; this results in enlargement of the nerve and blurring of its margin because of edema, inflammatory exudates, or prominence of the adjacent epidural veins

Lumbar diskography

Diskography is a controversial procedure. The value of diskography in determining a source of pain or whether surgery is necessary has not been proved. Its validity has been questioned on the grounds of technical errors and false-positive findings. Opponents of the procedure believe that false-positive findings are the result of psychosocial factors and/or neurophysiologic phenomena, such as central hyperalgesia in patients with chronic pain. The existence of clinically significant diskogenic pain is also questioned.

Proponents of diskography believe that it is the only method to diagnose diskogenic pain. They advocate strict selection criteria for patients and strict criteria for a positive diskogram result.

Diskography is used in several clinical situations, including the following:

  • Assessment of equivocal abnormalities seen on myelography, CT, or MRI
  • Detection of a symptomatic disk among multilevel abnormalities
  • Diagnosis of a lateral disk herniation
  • Provision of subjective support for the existence of diskogenic pain
  • Selection of fusion levels
  • Evaluation of the spine after surgery

These uses are not scientifically established.

The aim of diskography is to evaluate whether a disk is painful under certain conditions. The diskogram is less about the anatomy of the disk and more about its pathophysiology. A disk that looks abnormal on MRI may not be painful, whereas a minimally disrupted disk on MRI may be associated with severe pain on a diskogram.

Abnormal disks accept injection of more than 1.5 mL of normal saline or contrast material, with a spongy endpoint during injection. In abnormal disks, contrast material extends beyond the nucleus pulposus through annular tears or through a radial fissure. Because the outer anulus is richly innervated by the recurrent meningeal nerve, the anterior primary ramus, the mixed spinal nerve, and the gray ramus communicans, the pressure of the injected contrast material provokes pain.

When the pressure of the contrast material reaches the part of the disk in contact with the nerve root, radicular pain may be provoked.

Potential complications or adverse effects from diskography include exacerbation of pain, contrast agent allergy, nerve root injury, and chemical or bacterial diskitis.

CT diskography

This procedure should be performed within 4 hours of an initial diskography. Clinical applications include the following:

  • Determining whether a disk herniation is contained, protruded, extruded, or sequestrated
  • Distinguishing between mass effects from scar tissue or disk material in the spine after spinal surgery

Combination of imaging modalities

A combination of imaging modalities may be necessary to evaluate cervical stenosis and nerve root compression adequately. [11]

Plain cervical radiographs provide important information on alignment, degenerative bony changes, and deformities. Dynamic flexion/extension images are important to determine sagittal balance and the presence of osseous instability.

After plain radiography, MRI has become the study of choice in the initial evaluation of patients with neck pain. MRI provides images in multiple planes, is noninvasive, and is excellent for studying intrinsic cord disease.

Myelography with postmyelography CT is excellent for evaluating nerve root compression. With reconstructions, it also provides excellent details of the bony anatomy in multiple planes.

Previous
Next:

Procedures

Transforaminal selective nerve root blocks (SNRBs) have been used as both subjective diagnostic tools and therapeutic interventions for lumbar spinal stenotic levels. When MRI shows evidence of multilevel degenerative disk disease, SNRBs can be used to determine whether a specific nerve root is affected. The procedure involves injection of anesthetic and contrast at the nerve root level of interest under fluoroscopic guidance. This creates an area of hypoesthesia in the respective dermatome.

Anderberg et al investigated the correlation of SNRBs with MRI findings and clinical symptoms in cervical spines with multilevel degenerative disk disease. They found a 60% correlation with the most severe areas of MRI degeneration. In areas of neurologic deficit, dermatomal radicular pain showed a 28% correlation with SNRB results. [12]

SNRB can sometimes be a helpful tool together with clinical findings/history and MRI of the cervical spine for preoperative investigation in patients with multilevel degenerative disk disease who present with radicular pain.

Previous