Diagnostic Injections for Lumbar Disc Disease

Bogduk, N. Clinical Anatomy of the Lumbar Spine and Sacrum. Third Edition, 1997, Churchill Livingstone.

Radicular pain results from mechanical compression and/or chemical irritation of a nerve root. Establishing an anatomic diagnosis for patients with radicular pain is important, as there are treatments, such as surgery, that are directed towards specific pathology and have excellent outcomes in well selected patients. The source of radicular pain, typically either a herniated nucleus pulposus or lateral spinal stenosis, can be definitively diagnosed at surgery; therefore, there is a gold standard that can used to assess the validity of diagnostic studies. Consequently, the ability of both clinical findings and imaging studies to diagnose the site of pathology is well defined. A precision diagnostic injection may be indicated when imaging studies suggest that more than one nerve root may be responsible for a patient’s symptoms. In that circumstance, a selective epidural injection may be useful.

In contrast to radicular pain, the relationship between spinal pathology and lumbar axial pain is uncertain. There are a number of anatomic structures which are potential sources of pain, including myofascial tissues, synovial joints, and the intervertebral discs. While discogenic pain is felt by many to be an indication for surgical fusion, outcome studies have demonstrated variable results.

Colhoun, et al. Provocation Discography as a Guide to Planning Operations on the Spine. 1988 JBJS(Br) 70B:267-71.

Wetzel, et al. The Treatment of Lumbar Spinal Pain Syndromes Diagnosed by Discography. Spine 1994 19:7;792-800.

Fluke. Letter to the editor. Spine 1995 20:4;501-4.

Gill, et al. Functional Results After Anterior Lumbar Fusion at L5-S1 in Patients with Normal and Abnormal MRI Scans. Spine 1992 17:8;940-2.

Newman et al. Anterior Lumbar Interbody Fusion for Internal Disc Disruption. Spine 1992 17:7; 831-33.

Simmons, et al. An Evaluation of Discography in the Localization of Symptomatic Levels in Discogenic Disease of the Spine. Clinical Orthopedics and related Research. May, 1975. 108:57-69.

Parker, et al. The outcome of posterolateral fusion in highly selected patients with discogenic low back pain. Spine 1996 21:15:1835-8.

Greenough, CG, et al. Lumbar spinal fusion: a comparison of anterior and instrumented posterolateral technique. ISSLS abstracts, Vermont, June 1996.

Knox, BD, et al. Anterior lumbar interbody fusion for discogram concordant pain. Journal of Spinal Disorders 1993;6(3):242-4.

Lee CK, et al. Chronic disabling low back pain syndrome caused by internal disc derangements: the results of disc excision and posterior lumbar interbody fusion. Spine 1995 20(3):356-61.

Kuslitch BAK study.

Vamvanji, V, et al. Outcome and intertransverse fusion in internal disc disruption. ISSLS abstracts June 1996.

As there is no gold standard for diagnosing the tissue source of axial pain it is not possible to rigorously validate diagnostic studies (1). While discography is frequently performed on patients with axial pain it’s use remains controversial (2,3).

(1) Sackett, et al. Clinical epidemiology. A basic science for clinical medicine. Second edition. Little Brown and Company, 1991.

(2) Nachemson, Alf. Editorial Comment. Lumbar Discography- Where Are We Today? Spine 1989 14:6;555-7.

(3) Caragee, et al. The deceptive discogram: positive provocative discography as a misleading finding in the evaluation of back pain. Abstract, NASS annual meeting, 1997.

Complicating the diagnosis and treatment of spinal pain is the influence of psychosocial factors on pain. Pain is a complex phenomenon, with components secondary to both tissue injury and the emotional reaction to tissue injury. While there is considerable controversy regarding the relative importance of psychosocial and biologic factors in causing spinal pain (1,2, 5,6), there is evidence to suggest that the level of psychological distress can affect the results from diagnostic injections (3) as well as the outcomes from treatment (4).

(1) Sullivan, M. The problem of pain in the clinicopathologic method. Clinical Journal of Pain 1998 14(3):197-201.

(2) Reference from July, 1998 Spine- study on 25,000 work comp claims in Michigan- letter to editor in same issue from Hadler.

(3) Caragee, et al. The rates of false positive discography in select patients without low back complaints. Spine, in press.

(4) Shofferman, J. and Polatin, P. Psychological screening: How do we best use study results in clinical practice. Spine letter, September 1996:4-6.

(5) Wallis, et al. Pain and Psychologic Symptoms of Australian Patients with Whiplash. Spine 1996 21:7;804-10.

(6) Hansen, et al. Minnesota Multiphasic Personality Inventory Profiles in Persons With or With-Out Low-back Pain: A 20 year Follow-up Study. Spine 1995 20:2716-20.

It is important to recognize the potential importance of psychosocial factors in diagnosing and treating patients with spinal pain.

If surgery is being considered for a patient with spinal pain - and the source of pain is unclear despite a clinical evaluation, imaging studies, and potentially electrodiagnostics - a diagnostic injection may be indicated. For patients with suspected disc disease, either discography or a selective epidural injection may be considered, depending on whether the patient has radicular pain or axial pain.