You are in: eMedicine Specialties > Neurology > Headache and Pain DiscographyArticle Last Updated: Feb 21, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 11
  Author: Steven A Barna, MD, Medical Director of MGH Pain Clinic, Instructor of Anaesthesia, Department of Anesthesia and Critical Care, Harvard Medical School, Massachusetts General Hospital Steven A Barna is a member of the following medical societies: American Society of Interventional Pain Physicians Coauthor(s): Juan Santiago-Palma, MD, Consulting Staff, Department of Physical Medicine and Rehabilitation, Private Practice; Eugenia-Daniela Hord, MD, Instructor, Departments of Anesthesia and Neurology, Massachusetts General Hospital Pain Center, Harvard Medical School; Ricardo Vallejo, MD, PhD, Adjunct Professor of Biology, Illinois State University; Director of Research, Staff Pain Medicine, Millennium Pain Center; Aathi R Thiyagarajah, MD, Consulting Staff, Department of Rehabilitation Medicine and Pain Management, Oaktree Medical Center Editors: Joseph R Carcione, Jr, DO, MBA, Consultant in Neurology and Medical Acupuncture, Medical Management and Organizational Consulting, Central Westchester Neuromuscular Care, PC; Medical Director, Oxford Health Plans; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; James H Halsey, MD, Professor, Department of Neurology, University of Alabama Medical Center; Selim R Benbadis, MD, Professor, Director of Comprehensive Epilepsy Program, Departments of Neurology and Neurosurgery, University of South Florida School of Medicine, Tampa General Hospital; Nicholas Y Lorenzo, MD, Chief Editor, eMedicine Neurology; Consulting Staff, Neurology Specialists and Consultants Author and Editor Disclosure Synonyms and related keywords: back pain, discogenic pain, discogram, disk herniation, disk injection, herniated disk, internal disk disruption, intervertebral disk, neck pain, provocative discography, spine pain INTRODUCTIONSection 2 of 11
  Discography was first described in 1948 as an investigative technique for herniated nucleus pulposus. Since that time, new imaging techniques that are more appropriate for this diagnosis have been developed. Discography is currently used to determine whether the disk is the source of pain in patients with predominantly axial back or neck pain. During discography, contrast medium is injected into the disk and the patient's response to the injection is noted; provocation of pain that is similar to the patient's existing back or neck pain suggests that the disk might the source of the pain. Computed tomography (CT) is usually performed after discography to assess anatomical changes in the disk and to demonstrate intradiscal clefts and radial tears. Early studies suggested that discography had a low specificity, but more recent studies have failed to induce pain in asymptomatic controls, suggesting that discography has utility in identifying patients with discogenic pain. Pain reproduction during discography in symptomatic individuals is variable, with a lower incidence of pain reproduction in patients with disk degeneration than in those with posterior tears of the anulus fibrosus or significant disk bulges. Controlled clinical trials of discography are lacking, and a standard against which to compare is elusive. When comparing outcomes of fusion procedures, lumbar discography is sensitive but lacks specificity (see Images 1-3). INTERNAL DISC DISRUPTION AND PAIN PROVOCATION THEORIESSection 3 of 11
The cardinal lesion that renders a lumbar disk painful is internal disk disruption. The characteristic feature of internal disk disruption is a radial fissure extending to the innervated outer third of the annulus fibrosus. As radial fissures extend to the outer third of the annulus, nerve endings are exposed to the inflammatory and algogenic chemicals produced by nuclear degradation. As a radial fissure develops, fewer and fewer lamellae remain intact to bear the load. At some stage, the threshold for mechanical nociception will be attained, especially if the nerve endings have been chemically sensitized. Disk stimulation reveals this condition by showing a reduced threshold for mechanical stimulation of the disk. In theory, discography provokes pain by the following mechanisms:
INDICATIONSSection 4 of 11
Discography should be performed only if adequate attempts at conservative therapy and noninvasive diagnostic tests, such as MRI, have failed to reveal the etiology of back pain. Specific indications for discography include the following:
COMPLICATIONSSection 5 of 11
Complications associated with discography include spinal headache, meningitis, discitis, intrathecal hemorrhage, arachnoiditis, severe reaction to accidental intradural injection, damage to the disk, urticaria, retroperitoneal hemorrhage, nausea (2%), seizures (4%), headache (10%), and increased pain (81%). In rare cases, discography has been found to result in disk herniations. Five cases of acute lumbar disk herniation precipitated by discography have been reported. New-onset or a persistent exacerbation of radicular symptoms following provocative discography merits further investigation (Poynton, 2005). The incidence of discitis is 2-3% when a single-needle technique is used and 0.7% when a double-needle technique is used. The incidence of discitis might decrease to less than 1% when prophylactic antibiotics are used. PROCEDURESection 6 of 11
Technique
Interpretation
Dallas classification of discography results
PROS AND CONS OF LUMBAR DISCOGRAPHYSection 7 of 11
Pro Discography provides valuable information to the clinician and the patient. CT myelography and MRI are used to detect disk herniations and other space-occupying lesions that may compromise lumbar nerve roots. CT scans and MRI are excellent for investigating radicular pain, but offer little in the investigation of back pain and somatic referred pain. Opponents of discography refer to studies by Holt. However, the means and methods used by Holt have been scathingly refuted. His studies have been replicated using more stringent conditions, with blinded investigators, independent observers, and manometrically monitored discography. Under these conditions, lumbar disks do not hurt in asymptomatic individuals and disk stimulation is a highly specific diagnostic test. For a disk to be deemed painful, stimulation must reproduce the patient's accustomed pain, provided that stimulation of the disk above or below (preferably both) does not reproduce pain. Some surgeons have proclaimed that by selecting the correct disk for treatment, discography leads to greater success rates than anterior lumbar fusion. Disks selected for treatment are those that are symptomatic on stimulation and that express loss of signal intensity on MRI. Failing to find a painful disk on discography should preclude surgery; so too should finding multiple painful disks or obtaining indeterminate results. Discography is only a diagnostic tool to test whether a disk is painful. Unjustified surgery can be prevented by heeding indeterminate or negative results. Con Some authors believe that the test has no proven efficacy in improving patient outcomes, and that it leads to inappropriate surgery. These authors also believe that discography was popularized and adapted before validity and utility were determined. Disagreement on discography involves 3 major areas. The first area of disagreement on discography is the concept of internal disk disruption as a symptom-producing complex. Proponents of discography theorize that the cardinal lesion that renders a lumbar disk painful is internal disk disruption. However, authors that oppose discography believe that the concept is a combination of a variety of anatomic and physiologic facts garnered from disparate sources and cobbled together to provide a theory to support the concept of "internal disk disruption." The second area of disagreement is the contention that discography is important as an informational tool in "internal disk disruption" to help us understand what is or is not wrong. What is the point of an "informational tool" for the purpose of establishing a diagnosis for which no proven therapy exists? The third area of disagreement is that discography leads to inappropriate surgery. Nachemson stated that the origin of back pain remains unknown in a majority of patients. The benefit of surgery for low back pain and sciatica at the present time is proven in scientific matter only for disk herniation giving nerve root pain. REVIEW OF PUBLISHED STUDIESSection 8 of 11
Lumbar surgery Derby et al completed a multicenter retrospective study of long-term surgical and nonsurgical outcomes after lumbar discography in 96 patients. After positive lumbar discogram, patients underwent interbody fusion alone, combined fusion, intertransverse fusion, or no surgery. Those who underwent interbody/combined fusion had significantly better outcomes than those who underwent intertransverse fusion. Nonsurgical patients had the worst outcomes overall. Parker et al prospectively studied 23 patients treated by a single surgeon. All underwent preoperative discography and were monitored for an average of 4 years postoperatively. Thirty-nine percent had a good-to-excellent result, 13% a fair result, and 48% a poor result. Smith et al did a study of 25 patients who had a positive discogram of disk L4-5 or L5-S1; the analysis was retrospective, with mean follow-up of 5 years. Sixty-eight percent had improved, 8% were the same, and 24% had worsened. Outcome was not correlated with disk level, gender, or smoking history. Patients who had improved had a shorter history of low back pain and an older age of onset (45 y vs 33 y). Of patients who had worsened, 67% had psychiatric disease. Eighty percent of those receiving workers compensation had improved. Knox and Chapman performed a study in which 22 patients undergoing anterior lumbar interbody fusion for discogram-concordant lower back pain were evaluated retrospectively. Results were poor in all 2-level fusions. In single-level fusions, 35% had good, 18% fair, and 47% poor results. Wetzel et al did a retrospective review of 48 patients with low back pain who had discogram/CT then lumbar arthrodesis. Forty-six percent were judged to have satisfactory clinical outcome at final follow-up. Cervical surgery Motimaya et al performed a retrospective study of 46 patients who underwent cervical disk examination by discography. They then evaluated results of 14 of the 16 patients who underwent cervical spine fusion at those levels in accordance with positive results on discogram. The average symptomatic period prior to discography was 12 months, and cervical disk pain was localized in all 16 patients. After discectomy and anterior fusion, all 14 patients had good-to-excellent results at 6 months. Siebenrock and Aebi retrospectively reviewed 27 patients who underwent fusion of 39 cervical levels for discogenic pain. The source of pain in all patients was identified by positive discography. Fusions were performed via a ventral approach and included 22 1-level, 7 2-level, and one 3-level procedures; iliac bone graft was done in all patients. Seventy-three percent had good-to-excellent results, 23% had fair results, and 3.8% had poor results. More good-to-excellent results were seen after 2-level than after 1-level fusion (86% vs 62%). Furthermore, patients with pain to the upper limbs did better. Connor and Darden did a retrospective review of 31 patients who had positive discogram. Twenty-two underwent anterior cervical discectomy and fusion. One patient had a good-to-excellent result, 41% had good results, and 54% had fair to poor results. Whitecloud and Seago retrospectively reviewed 34 patients who had cervical arthrodesis after positive discogram. Seventy percent of the patients had good-to-excellent results. Supporting evidence Heggeness et al performed a retrospective review of 83 patients presenting with disabling back pain who had previously undergone surgical treatment for herniated nucleus pulposus. They found a high incidence (72%) of concordant pain with discography of the previously operated level. Only 34% of the previously operated disks demonstrated posterior extravasation of discography dye. Persistence of a posterior annular defect was associated with a higher incidence of concordant pain. Brightbill et al reported on a clinical series of 7 patients who had surgically proven internal disk disruption, normal results on MRI, and abnormal morphology on discogram. They concluded that discography may be useful in patients with persistent symptoms despite a normal or equivocal MRI. Bernard prospectively studied 250 patients with low back pain who underwent lumbar discography followed by CT scan. In 93% of the patients, the combined discogram/CT provided significant information regarding equivocal or multiple level abnormalities and type of herniation, defining surgical options, and evaluating previously operated spines. In 94% of the patients, discography/CT correctly predicted disk herniation as protruded, extruded, sequestrated, or internally disrupted. Lam et al did a prospective blinded study in which they found a significant correlation between abnormal disk morphology and the high-intensity zone (HIZ) on MRI (see Image 6). In morphologically abnormal disks (grades 3, 4, 5), a significant correlation between HIZ and reproduction of exact or similar pain is typical. Sensitivity, specificity, and positive predictive value for pain reproduction were 81%, 79%, and 87%, respectively. Saifuddin et al retrospectively reviewed 99 lumbar discogram reports in which 260 disks were injected and 179 were abnormal. They found that pain experienced in buttock, hip, groin, or lower limb can arise from the posterior annulus without direct involvement of the root. Simmons et al performed a study in which 164 patients, all with low back pain, underwent discography and MRI (1991). Discography and MRI results correlated in 80% of the cases. Of abnormal disks, 76% reproduced symptoms on discography. Antti-Poika et al did a prospective study of 279 injected disks in 100 patients. Exact reproduction of pain on injection was more common in fissured or ruptured disks. The results indicated that discography had a sensitivity of 81% and specificity of 64% for pain. Additional information yielded by follow-up CT scan was minimal. Schellhas et al conducted a retrospective study of patients until records of 100 HIZ disks in 63 patients were found. Eighty-seven of the 100 disks tested were found to be concordantly painful. All 87 showed annular tears to the outer third of the anulus fibrosus. Of the 67 non-HIZ disks also studied, 64 were nonconcordant and of lower sensation intensity. In patients with symptomatic lower back pain, the HIZ is a reliable marker of painful outer annular disruption. Contradictory evidence Caragee et al conducted a prospective study of 8 patients (24 disks) with no history of lower back pain who had undergone posterior iliac bone graft (1999). He found that 50% experienced concordant pain of the usual gluteal area. Thus, the ability of a patient to separate concordant pain on discography may be less meaningful than often assumed. In another study by Caragee, 26 patients without lower back pain were studied prospectively after discography. He surmised that, in a subject group with no lower back pain but with significant emotional and chronic problems, discography might result in reports of significant back pain. In fact, he found that for at least 1 year after injection, 66% of the somatization group and 40% of the abnormal psychometric test result group did indeed have significant back pain. Of 11 subjects with normal psychometric test results, none reported significant long-term back pain after discography. In yet another study by Carragee, he reviewed a clinical series showing that pain intensity during discography injection is influenced strongly by the subject's emotional and psychological profile. Pain reproduction also was related primarily to penetration of the dye through the outer annulus and could not be used reliably to confirm the location of pain source. Finally, Carragee also prospectively studied patients with and without lower back pain after laminotomy and discectomy. From a cohort of 240 patients who had undergone single-level discectomy, 20 asymptomatic patients with normal psychometric test results were recruited for 3-level discography. A control group consisted of 27 symptomatic patients who had undergone single-level discectomy. The asymptomatic patients had a 40% rate of positive injection, while the symptomatic group had a rate of 63%. Grubb and Kelly conducted a retrospective study of 173 cervical discograms over 12 years. Of the 807 disks injected, 50% yielded concordant pain response. More than half of the discograms yielded 3 or more painful disks (more than expected). Manabu performed a study in which 101 lumbar disks in 39 patients were studied with MRI and discography. He found that although lumbar disks with posterior combined annular tears are likely to produce pain on discography, this provoked pain was not predictive of discogenic pain. CONCLUSIONSection 9 of 11
The use of discography remains controversial. However, the literature supports the use of discography in selected patients. Particular applications include patients with persistent pain in whom disk abnormality is suspected but noninvasive tests have not provided diagnostic information or needs to be correlated with clinical symptoms. Discography can also be helpful in the assessment of disks in patients in whom fusion is being considered and in whom pain remains after surgery. For excellent patient education resources, visit eMedicine's Bone Health Center. Also, see eMedicine's patient education articles Back Pain and Shoulder and Neck Pain. MULTIMEDIASection 10 of 11
REFERENCESSection 11 of 11
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