Degenerative Disc Disease

Overview

Degenerative disc disease (DDD) is typically used to describe the clinical scenario of low back pain and wear-and-tear (arthritic) changes of the intervertebral disc. To classify this condition as a "disease" is probably inappropriate, because nearly every person will develop degenerative changes of the intervertebral disc during their lifetime, many beginning in the third decade of life. The disc is a cartilaginous symphysis joint that bears nearly 90% of the load of the spine, while the facet joints bear approximately 10%. The discs of the spine are joints, and just like all joints in the human body, the discs undergo arthritic changes during the course of life. Despite being so prevalent, the vast majority of people never develop significant chronic back pain as a result of this condition. The concept of a discogenic injury and degeneration causing back pain was first reported by Goldthwait in 1911, followed by a larger study in 1925 by Danforth and Wilson. Kirkaldy-Willis described the diagnosis as a cascade of degeneration with four phases. There are some patients who develop severe back pain solely due to degenerative disc disease, yet the majority of patients with severe symptoms also have some other spinal disorder such as herniated disc, spinal stenosis, fracture, or spondylolisthesis.

Causes

There are a number of specific causes of degenerative disc disease, ranging from an initial injury to the annulus (outer ring of the disc), facet joint injury, fractures, infections or rheumatologic etiologies (causes). Many of these conditions affect the biomechanics and/or biologic characteristics and ultimately lead to a derangement of the normal cartilage and its ability to function. However, the precise cause of DDD is unknown in most cases, yet is assumed to be the result of normal aging in most of these cases.

Symptoms

As previously discussed, the majority of people with degenerative disc disease do not have significant debilitating symptoms. The patients that do have pain generally have a predominance of low back in the region of the disc disease. Unless there is another associated condition, patients generally do not leg pain symptoms or neurologic abnormalities such as weakness, numbness, or bowel/bladder dysfunction.

Physical Findings

The physical findings for degenerative disc disease are nonspecific. Patients may have an antalgic gait and significant lumbar tenderness if the pain is severe. Often, the lumbar range-of-motion is decreased, but the neurologic examination is normal. Special tests such as the straight leg raise test and Leseague's test are usually negative.

Imaging Studies

X-rays may show that a disc height is diminished, thus confirming the diagnosis of DDD. An MRI is generally recommended so as to identify if there is an associated disc herniation or spinal stenosis, which would impact the treatment regimen. An MRI will also clarify the severity of degenerative disc disease.

Laboratory Tests

There are no laboratory tests used to diagnose a herniated disc. Occasionally, specific tests are ordered to rule out infection or other medical/rheumatologic conditions.

Special Tests

A discogram is a test that is performed to help identify which degenerated disc, if any, is causing a patient's back pain. A doctor performs this procedure by injecting radiopaque dye, under pressure, into the discs of the lumbar spine. The procedure is performed using fluoroscopy, a special x-ray machine that allows x-ray images to be viewed instantly on a television monitor.

Diagnosis

The diagnosis of degenerative disc disease is ultimately confirmed if moderate or severe disc height loss is observed on a lumbar x-ray. Otherwise, an MRI test would be required to identify this condition if there is only mild DDD. The doctor must then evaluate the location and quality of the back pain to determine if the degenerated disc is actually generating the patient's pain.

Treatment

The treatment for degenerative disc disease is primarily conservative. The majority of patients with significant pain generally improve with time, as well as non-operative treatments such as oral medications, physical therapy, and other modalities. Epidural steroid injections and facet joint injections are usually not efficacious unless there are other associated spinal conditions such as spinal stenosis, herniated disc, etc.

Patients that fail all conservative treatments and still have disabling degenerative disc disease pain after 6-12 months are considered candidates for surgery. It is usually advised and recommended that a patient undergo discography prior to surgery to identify the specific disc that is generating a patient's pain. However, some authors argue that discography is not a very reliable or valid test, and is not always necessary or useful. The surgery for isolated degenerative disc disease is spinal fusion or artificial disc replacement (disc arthroplasty). A disc excision, decompression, and/or laminectomy may also be required if a patient has concomitant spinal stenosis or disc herniation.

Bibliography

Boden SD, Davis DO, Dina TS, et al: Abnormal magnetic-resonance scans of the lumbar spine in asymptomatic subjects: a prospective investigation. J Bone Joint Surg [Am] 1990 Mar; 72(3): 403.

Bogduk N, Modic MT: Lumbar discography. Spine 1996 Feb 1; 21(3): 402.

Bogduk N: The innervation of the lumbar spine. Spine 1983 Apr; 8(3): 286.

Bush K, Cowan N, Katz DE, Gishen P: The natural history of sciatica associated with disc pathology: a prospective study with clinical and independent radiologic follow-up. Spine 1992 Oct; 17(10): 1205.

Butler D, Trafimow JH, Andersson GB, et al: Discs degenerate before facets. Spine 1990 Feb; 15(2): 111.

Danforth M,Wilson P: The anatomy of the lumbosacral region in relation to sciatic pain. J Bone Joint Surg Am 1925;7:109.

Deyo RA, Tsui-Wu YJ: Descriptive epidemiology of low-back pain and its related medical care in the United States. Spine 1987 Apr; 12(3): 264.

Donelson R, Aprill C, Medcalf R, Grant W: A prospective study of centralization of lumbar and referred pain. A predictor of symptomatic discs and annular competence. Spine 1997 May 15; 22(10): 1115.

Frymoyer JW, Pope MH, Clements JH, et al: Risk factors in low-back pain: an epidemiological survey. J Bone Joint Surg [Am] 1983 Feb; 65(2): 213.

Frymoyer JW: Back pain and sciatica. N Engl J Med 1988 Feb 4; 318(5): 291.

Goldthwait JE: The lumbosacral articulation: an explanation of many cases of lumbago, sciatica, and paraplegia, Boston Med Surg J 1911;164:365.

Hazard RG, Fenwick JW, Kalisch SM, et al: Functional restoration with behavioral support: a one-year prospective study of patients with chronic low-back pain. Spine 1989 Feb; 14(2): 157.

Ito M, Incorvaia KM, Yu SF, et al: Predictive signs of discogenic lumbar pain on magnetic resonance imaging with discography correlation. Spine 1998 Jun 1; 23(11): 1252-8; discussion 1259.

Jackson HC 2d, Winkelmann RK, Bickel WH: Nerve endings in the human lumbar spinal column and related structures. J Bone Joint Surg [Am] 1966 Oct; 48(7): 1272.

Jaffray D, O'Brien JP: Isolated intervertebral disc resorption. A source of mechanical and inflammatory back pain. Spine 1986 May; 11(4): 397.

Jensen MC, Brant-Zawadzki MN, Obuchowski N, et al: Magnetic resonance imaging of the lumbar spine in people without back pain. N Engl J Med 1994 Jul 14; 331(2): 69.

Kirkaldy-Willis WH: The pathology and pathogenesis of low back pain. In: Managing Low Back Pain. New York, NY: Churchill Livingstone; 1988: 49.

Lacroix JM, Powell J, Lloyd GJ, et al: Low-back pain. Factors of value in predicting outcome. Spine 1990 Jun; 15(6): 495.

Lee CK, Vessa P, Lee JK: Chronic disabling low back pain syndrome caused by internal disc derangements. The results of disc excision and posterior lumbar interbody fusion. Spine 1995 Feb 1; 20(3): 356.

McCarron RF, Wimpee MW, Hudkins PG, Laros GS: The inflammatory effect of nucleus pulposus: a possible element in the pathogenesis of low-back pain. Spine 1987 Oct; 12(8): 760.

Modic MT, Masaryk TJ, Ross JS: Imaging of degenerative disk disease. Radiology 1988 Jul; 168(1): 177.

Modic MT, Steinberg PM, Ross JS, Carter JR: Degenerative disk disease: assessment of changes in vertebral body marrow with MR imaging. Radiology 1988 Jan; 166(1 Pt 1): 193.

Nachemson A, Morris JM: In vivo measurements of intradiscal pressure: discometery, a method for the determination of pressure in the lower lumbar discs. J Bone Joint Surg Am 1964 Jul; 46: 1077.

Pritzker KP: Aging and degeneration in the lumbar intervertebral disc. Orthop Clin North Am 1977 Jan; 8(1): 66.

Resnick D: Degenerative diseases of the vertebral column. Radiology 1985 Jul; 156(1): 3-14.

Schneiderman G, Flannigan B, Kingston S, et al: Magnetic resonance imaging in the diagnosis of disc degeneration: correlation with discography. Spine 1987 Apr; 12(3): 276.

Schwarzer AC, Aprill CN, Derby R, et al: The prevalence and clinical features of internal disc disruption in patients with chronic low back pain. Spine 1995 Sep 1; 20(17): 1878.

Sether LA, Yu S, Haughton VM, Fischer ME: Intervertebral disk: normal age-related changes in MR signal intensity. Radiology 1990 Nov; 177(2): 385.

Von Korff M, Deyo RA, Cherkin D, Barlow W: Back pain in primary care: outcomes at 1 year. Spine 1993 Jun 1; 18(7): 855.

Walsh TR, Weinstein JN, Spratt KF, et al: Lumbar discography in normal subjects. A controlled, prospective study. J Bone Joint Surg [Am] 1990 Aug; 72(7): 1081.

Weinstein J, Claverie W, Gibson S: The pain of discography. Spine 1988 Dec; 13(12): 1344.

Yu S, Haughton VM, Sether LA, et al: Criteria for classifying normal and degenerated lumbar intervertebral disks. Radiology 1989 Feb; 170(2): 523.