Cervical Discography: Diagnostic Value and Complications

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CHAPTER 67 Cervical Discography: Diagnostic Value and Complications

Richard Derby, Renée Melfi, Gul Talu, Charles Aprill

INTRODUCTION

Diagnostic procedures can confirm specific diagnoses. Establishing a correct diagnosis should allow prediction of outcome following appropriate treatment. To evaluate the diagnostic value of a procedure one must determine how well the test can discriminate between the diseased and nondiseased state. A diagnostic test is accepted or rejected after evaluating evidence, based on an accepted methodology. One must ask, is there historical need for the test, are there studies that validate acceptable specificity and sensitivity, are there other comparable, less invasive procedures, is the test clinically useful, is the incidence of significant morbidity low, and finally are serious complications preventable?¹

In the case of cervical discography, the diseased state is the presence of a symptomatic disc. Ideally, discography would always be positive at a symptomatic disc and always be negative in an asymptomatic disc. A perfect procedure would be inexpensive, relatively painless, and free of serious complications. Cervical discography is not perfect. If sensitivity and specificity are acceptable and the results of this test can predict outcome of treatment, then in the absence of another less invasive test that will provide comparable information, one can justify the cost and risk of this less than perfect diagnostic procedure.

Historical need

Ralph Cloward acknowledged that George Smith performed the first cervical discography in1952, but both independently described the technique and use of cervical discography in the late 1950s.²^–⁴ These surgeons were performing anterior cervical fusions for chronic axial pain and were searching for a procedure to identify the painful cervical discs. Both were frustrated by the insensitivity of available diagnostic tests. Plain film could diagnose disc degeneration but there was poor correlation with pain. Myelography with Pantopaque could identify central and paracentral disc herniation but the false-positive incidence was high, and myelograms were insensitive to lateral lesions.

Both surgeons felt that reproduction of a patient’s usual pain during disc injection was evidence that the disc was symptomatic. Cervical fusions were performed based on this information. They recognized that most discs were anatomically disrupted,^3,⁵ but not all were painful. Controversy arose because many surgeons felt that cervical spine surgery should not be performed for neck pain without radiculopathy. Cervical discography was berated because of the high prevalence of structurally abnormal cervical discs and because injection into most cervical discs provoked pain.²^–¹⁶ None of the early reports mentioned the imprecise methods used to perform and evaluate discography. Many surgeons perceived cervical discography as a useless procedure.^9,^12,¹⁶ On the other hand, there were others who believed in discogenic pain, used discography to identify painful discs, and fused cervical segments found to be positive.^3,^5,^7,¹³

Sensitivity and specificity

Since neck pain from a painful disc is not life-threatening and cervical spine fusion is not a benign treatment, the ideal diagnostic test should have high specificity (i.e. a low false-positive rate). To establish the specificity and sensitivity of provocative discography requires a randomized, blinded trial in a group of patients with chronic axial neck pain. The predictive variable would be the result of discography as defined by strict criteria. The outcome variable would be the presence or absence of a painful disc as determined by a gold standard. Unfortunately, no gold standard exists. Therefore, one cannot directly determine either the specificity or sensitivity of cervical discography.

We can indirectly evaluate the specificity of cervical discography. Specificity is the measure of how well cervical discography can rule out a disc as a pain generator when the pain is caused by some other structure. Specificity equals true negative divided by (false positive + true negative). Ideally, one would perform discography on patients with chronic axial neck pain and patients with neck pain referred from other body regions. A less robust design would be to perform discograms on asymptomatic volunteers. This design, however, might give a higher false-positive rate because concordance of pain cannot be evaluated in asymptomatic volunteers. As with lumbar discography,¹⁷^–¹⁹ a significant proportion of asymptomatic individuals with degenerated discs will have low-level pain during disc injection. A positive response should include a limiting verbal pain score (e.g. > 6–7/10 pain). Provoked pain below that level does not constitute a positive response. Alternatively, one could identify patients with painful Z-joints as the source of neck symptoms and perform discography on them. Patients with a positive discogram response who also had complete relief of their pain following placebo-controlled analgesic medial branch blocks are discogram false-positive responders.

Soon after the separate introduction of cervical discography by Smith and Cloward in the late 1950s, Holt reported on the ‘fallacy of cervical discography.’ He performed discography on 50 ‘normal’ subjects who were inmates at the Missouri State Penitentiary.¹² A total of 148 discs in 50 subjects were studied using 22-gauge needles placed in the neck blindly, using X-rays to document needle placement in the discs. Each ‘extremely co-operative’ inmate was given either Demerol or Nembutal 20 minutes before the procedure. Each disc was injected with 50% sodium diatrizoate (Hypaque sodium) and ‘… even in 0.2 cc amounts, great pain was produced in every subject at every space.’ Holt reported that every disc hurt when injected (i.e. the specificity was 0%). He observed that the pain lasted 5 minutes then subsided. Pain was variously described as ‘being hit in the back of the neck with a maul,’ ‘like sticking a knife into the base of my neck,’ or ‘a hot poker between the shoulder blades.’ He described almost 100% incidence of contrast extravasation despite a volumes of only 0.2–0.3 mL. According to Holt, only one inmate reported to sick call and all others resumed normal activity the next day without apparent problems. He did conclude that cervical discography might be made relevant by a radical change in contrast media and ‘techniques of performance.’ He politely conceded that further studies should be done to establish objective findings, including control patterns in normal individuals.

A decade later in 1975, Holt reflected on the value of cervical discography by rehashing his previous observations and commenting on Struck’s study of 1200 patients undergoing cervical discography followed by about 800 surgical fusions.²⁰ Holt comments, ‘Colorado has had statehood slightly less than 100 years. It is hard to conceive of so many ruptured cervical discs in all its history.’ He called for a ‘hard and fast moratorium on cervical discography.’²¹

Other early observational studies also noted a high incidence of painful disc injections.

Meyer discounted the use of cervical discography because almost all the radiographic patterns were abnormal and he felt ‘there was no good correlation of pain radiation with the patient’s clinical symptoms or the roentogenographic findings.’¹⁰ Klafta and Collis discounted the 89% of positive pain provocation in patients because injection of contrast into cervical discs shown to have disc herniation on myelography did not usually reproduce the patient’s radicular pain.¹⁶

Despite negative bias, suboptimal imaging, and the use of irritating contrast, cervical discography was criticized but not challenged with new data for many years. In 1993, Shinomiya et al. in Japan partially reconfirmed Holt’s findings.²² These authors performed discography on 128 patients with spondylotic mylelopathy and radiculopathy. In the 72 patients with neck pain, 65% had reproduction of their usual pain. However, in the control group who had only neurologic symptoms, 50% reported pain provocation during injection.

In the same year, Aprill and Bogduk found a potential source of the high false-positive rate of cervical discography while studying the prevalence of Z-joint and discogenic pain in patients with chronic axial neck pain.²³ The authors performed both diagnostic medial branch blocks using a double-block protocol and cervical discography on a series of patients. Forty-one percent of patients had a positive discogram, but also had full relief of their axial neck pain for the duration of the local anesthetic following medial branch block with 0.5 mL of bupivacaine. These were false-positive discograms.

In 1996, Kurt Schellhas, an experienced interventional radiologist, reported a 0% false-positive rate by using more precise methods and strict criteria for defining a positive response.²⁴ He published a prospective observational study in which discography was performed on 40 discs in 10 asymptomatic volunteers and compared the results to 10 symptomatic patients. He used modern discography technique including 25-gauge needles, fluoroscopic guidance, and nonirritating contrast material. He also precisely graded pain intensity on a 10-point verbal pain scale, recorded the exact pain referral pattern, disc morphology, and pain concordance in patients. A minimum of four levels were studied in each patient. The mean age of the volunteers was 30 years. The disc morphology was abnormal in 35 of the 45 discs studied. While most abnormal discs did produce pain, the average pain was 2.42/10 (SD = 1.5). The most frequent response (14 discs) was 2–2.5/10 intensity. Pain intensity was 0–3/10 in 27 discs and 3–6/10 in 9 others. An intensity of 6/10 pain was reported in only one disc. By comparison, there were only two morphologically normal discs in the symptomatic group, but the average pain intensity and standard deviation was not calculated. The patient raw data show that there were 12 discs with minimal (0–3/10) pain responses, 11 with moderate (4–6/10) pain, and 17 discs with severe pain (7–10/10). In those moderately painful discs which might be most likely to be false-positive responses less than 50% (5/11) had concordant pain.

The results are a ‘best case’ scenario. The stimulus intensity is manual and operator dependent. One would expect that the author very carefully injected the asymptomatic volunteers. In addition, the volunteers were not chronic pain patients and were probably not blinded to the purposes of the study. If one accepts that a 7/10 intensity of pain provocation is required for a positive response, there was a 0% false-positive rate. If on the other hand, one logically infers that a 4–6/10 intensity of pain could easily be reported as 7/10 or greater intensity by a chronic pain patient, nine of the discs might have been reported positive, resulting in a false-positive rate of about 20–25%. But since 50% of these discs had nonconcordant pain, the actual false-positive rate is likely to be less than 20%.

Lastly, in 2000, Ohnmeiss and Guyer indirectly commented on the specificity of cervical discography by comparing the post-discogram computed tomography (CT) image and the pain response in 269 discs in 161 patients. They found a significant relationship between radiographic degree of disc disruption and the occurrence of clinical pain provocation. In only 14.3% of the normal discs was concordant pain provoked during injection. On the other hand, 77.8% of the disrupted discs were clinically painful. Although some of the degenerated and leaking discs in the older patients were not symptomatic, injection into most disrupted discs provoked concordant pain. Unfortunately, only pain concordance and disc disruption was evaluated. No data were on the intensity of pain provocation.

Competing diagnostic tests

If there is a less invasive, safer diagnostic test that will determine whether the disc is a source of pain, discography is not needed. Magnetic resonance imaging (MRI) scans are used to evaluate the structural morphology of cervical discs and have mostly replaced myelography and CT scans for imaging of the cervical spine. MRI can identify disc protrusions and degrees of disc degeneration. MRI scans are routinely used for surgical planning; not all patients are studied with discography.

MRI

Structural correlation

Patients with predominately axial neck pain, who have failed conservative care, and have unacceptable persistent symptoms may be surgical candidates. A surgeon must determine which level or levels are causing the pain prior to any operation. Because of the high sensitivity of MRI, some authors suggest that MRI can replace discography.^25,²⁶ MRI does demonstrate disc morphology, disc degeneration, and the contour of the outer anulus. But the clinical significance of these abnormalities in the absence of neural compression and radiculopathy is unclear. Are MRI findings of disc degeneration or minor protrusion of clinical importance?^27,²⁸

The presence of annular tears and loss of hydration are non-specific findings and many asymptomatic individuals have significant degenerative MRI structural abnormalities.²⁹ Normal discs are uncommon after the mid-twenties and the development of posterior lateral fissures through the uncinate region are present in the majority of mature cervical discs.³⁰ Since the early use of cervical discography, authors have reported the high incidence of annular tears in most cervical discs,^2–12,³¹ but the sensitivity of an MRI scan compared to discography for detecting degeneration and annular tears in cervical discs is still debated.

Gibson et al. examined 22 patients with both MRI and discography and on the basis of gross degeneration reached the conclusion that MRI scan was better for detecting gross degeneration.²⁵ On the other hand, Schellhas et al. prospectively correlated MRI imaging and discography in 10 asymptomatic subjects and 10 patients with chronic axial pain.²⁴ The authors found that various degrees of annular disruption were common in both symptomatic and asymptomatic subjects. The ruptures were usually posterolateral and full-thickness tears and leaks into the epidural space occurred in about 50% of the discs. Annular tears were identified during discography in 23 of 24 discs judged normal on MRI scans.

Pain provocation correlation

If one could predict pain provocation during discography based on the degree of signal changes, annular tears, or minor posterior annular contour abnormalities, discography is not necessary. Although prior studies correlating MRI findings with pain provocation during lumbar discography suggest that dark discs are often associated with positive pain provocation,^32,³³ this relationship in the cervical spine is less clear.

Parfenchuk and Janssen correlated the relationship between the MRI and CT scan obtained after cervical discography.³⁴ They found no correlation between the MRI scan and the post-discogram CT scan to the pain response during discography. Although there was a significant correlation between the patterns seen on the MRI scan and discography, MRI had a high false-positive and false-negative rate compared to discography. They found that unlike lumbar discs, 63% of the ‘white’ cervical discs (normal) studied by discography had a positive pain response. The authors concluded that dark discs need not be studied by discography, but their study included few dark discs. Their findings were not supported by Zheng et al., who found only 63% of the dark discs were symptomatic.³⁵ Furthermore, Schellhas et al. found that in their symptomatic patient group, 16 discs that were clearly abnormal on MR were negative to discographic testing, and 8 of 10 discs with normal MRI scans were shown to have fissures and provoke concordant pain during discography. In the asymptomatic group, 21 of 40 discs had abnormal morphology and none was symptomatic during discography.²⁴

Surgical predictive value based on MRI compared to discography

If one is to use MRI to identify a painful disc, all must agree on what MRI criteria will be used to select a symptomatic disc. The levels in question are those with lesser degrees of structural abnormalities, and not those with significant structural abnormalities that will be included in proposed fusion regardless of the discogram findings. Furthermore, we assume that other pain generators such as the Z-joints have been ruled out using appropriate analgesic testing. To compare outcome of surgery based on MRI scan alone or MRI plus discography, one would ideally randomize patients with similar clinical axial pain symptoms and similar structural pathology to undergo planned surgery based on either selection method and compare outcomes at various time intervals after surgery.

There are no prospective randomized studies, but Zheng et al. indirectly arrived at the possible false-negative and false-positive rate for surgery based on MRI scans.³⁵ This study retrospectively reviewed surgical outcome of 55 patients, between 1990 and 1995, who had clinically diagnosed cervical discogenic pain for at least 6 months and underwent an anterior cervical discectomy and fusion using a Simmons keystone technique and were available for follow-up at a minimum of 2 years. All had a preoperative MRI scan, discography, and a post-discogram CT scan. MRI disc morphology was classified as white, speckled, or dark and the integrity of the posterior anulus described as flat, bulging, torn, or small herniation. Discs that were thought to be symptomatic included dark herniated, dark torn, dark bulging, speckled herniated, speckled torn, and white herniated discs. Discography was performed by expert interventionists at an average of 2.9 levels using standard modern techniques. Discography was positive if injection of contrast provoked moderate or severe familiar pain. The MRI findings in 13 of 55 (24%) patients and 103 of 161 (64%) injected discs correlated completely with the results of discography. In the 79 discs with a normal MRI scan 58 (73%) had painful (positive) disc injections. Discography spared 21 asymptomatic discs from being fused and identified 21 discs that were deemed symptomatic but had a normal MRI scan. Since 58 of 79 levels with positive discography were abnormal on MRI, the MRI scan sensitivity was 73.4% (or a false-negative rate of 26.6%). There were 82 levels with negative discography and 40 of these levels had normal MRI scans resulting in an MRI specificity of only 49% when compared to positive discogram responses. Fifty-five patients had a total of 79 levels fused with overall clinical results of excellent in 49%, good in 27%, fair in 18%, and poor in 6%. The results showed that positive discography occurred in 59% of small herniated and torn discs, 35% of bulging discs, and 29% of flat discs. Dark discs with small herniations were the most commonly fused levels and 67% of these discs had a positive discogram.

Because discography was used as the criterion standard, levels with positive discograms and ‘negative’ MRI scans were fused and therefore there is no way of telling whether the results would have been the same, better, or worse if the segment was not fused.

Nerve root block

Kikuchi et al. combined cervical discography with diagnostic transforaminal nerve root sleeve injections to help localize symptomatic levels when the available imaging including routine radiography, flexion–extension films, myelography, phlebography, or epidurography was inadequate ³⁶ These authors felt provocation of pain at discography alone was inadequate because of the frequent occurrence of disrupted discs, the sensitivity of the anterior and posterior longitudinal ligaments, and the irritation caused by contrast material. They also warned about false-positive responses caused by placing the needle close to the endplate. They did, however, feel that reliable information could be obtained by using a nonirritating injectate such as normal saline or local anesthetic and by infiltrating the anterior longitudinal ligament with contrast prior to injection. Relieving the patient’s pain by local anesthetic infiltration of the nerve root sleeve confirmed the diagnosis, ‘even if there was no clinical evidence of impaired conduction in the roots.’

Analgesic discography

Analgesic discography is relief of pain rather than provocation and was first described by Roth in 1976.³⁷ Between 1968 and 1974 he preformed cervical analgesic discography in 71 consecutive patients having the ‘clinical diagnosis of medically intractable cervical-discogenic syndromes.’ All patients underwent plain roentgenograms, myelograms, provocative discograms, and analgesic discograms. Analgesic discograms were performed only when the patient was symptomatic (actively painful), without sedation, and at one level at a time. One mL of a 2% ‘analgesic solution’ was injected into the disc through a 22-gauge needle. After each injected level the patient was passively and actively tested, and painless manipulation was considered a positive response. All 71 patients had a least one positive level. In comparison, Roth states that only 21 patients, or 30% of the same group, experienced characteristic pain patterns during provocative discography. He reported that following fusion 93% of the patients had minimal or no symptoms and returned to work.

In 1987, Osler reported an 81% excellent or good result after cervical fusion based on the results of analgesic cervical discography.³⁸ No other studies have been published validating these two studies. This technique is used in unclear cases by some interventionists, including the two senior authors (R.D. and C.A.).

CLINICAL UTILITY

Cervical fusions are most commonly performed in patients with chronic unresolved axial neck pain and referred upper extremity pain. Many of these patients are in the worker’s compensation and legal system and surgical results may be less than optimal because of the significant influence of psychosocial factors on outcome.³⁹ An average of 66–75% success rate may be the best one can achieve by fusing the affected segments but outcome will obviously depend on the criteria used to define success.

Although advanced imaging studies provide improved three-dimensional anatomic definition, low specificity has precluded the use of imaging studies alone for selecting surgical levels when chronic axial, mechanical neck pain is a dominant complaint. Consequently, there is a need for provocative and analgesic diagnostic cervical injections (i.e. discography and cervical zygapophyseal joint block) on which to base selection of the level to be fused when history and examination suggest a patient to be an operative candidate.

Selecting fusion levels

Garvey et al. retrospectively compared patient-perceived outcome following cervical fusion for predominately mechanical cervical axial pain.⁴⁰ Of 87 patients meeting the inclusion criteria and available for follow-up, 66 had undergone cervical discography. A ‘clean pattern’ was defined as significant, concordant reproduction of pain at the affected levels with little or no pain at the adjacent levels studied. If these criteria were not meet, the discogram was classified as ‘nonclassic.’ Of the 66 patients, 35 (53%) had a clean pattern and 31 (46%) a nonclassic pattern. Good to excellent outcomes were reported in 91% of the clean group compared to 68% of the nonclassic pattern (p= 0.016). Twenty-one (24%) of the 87 patients did not undergo discography. They generally showed obvious grossly abnormal discs with normal discs above and below; 18 (86%) had good to excellent outcomes.

Earlier less rigorous retrospective surgical outcome studies also reported good outcomes following cervical fusions based on discography. In 1975, Simmons and Segil determined the levels to fuse based on the results of provocative discography performed by experienced radiologists.⁴¹ Discography was deemed positive if concordant pain was provoked using a standard anterolateral technique. Emphasis was given to repeat testing and making sure the patient was blinded to the level injected. Other than discography, at that time, only clinical impressions and myelography were available to determine the symptomatic levels. There was significant disagreement between the levels selected on the basis of clinical impression and myelography versus discography. Good surgical results were obtained in 30 of the 31 patients operated at levels determined by discography, ‘all having immediate lessening of symptoms and complete relief of symptoms by 1 week.’

Whitecloud and Seago retrospectively evaluated their results of cervical fusions in 40 patients with chronic mechanical neck pain of 27 months duration on average.⁴² Surgery was based on the results of cervical discography performed by the surgeon first author. A positive result was determined when the patient reported intense concordant pain provocation with injection of no more than 0.5 mL of contrast medium, followed by ‘prompt relief of the patient’s symptoms’ after injection of 0.2 cc Xylocaine. Usually, three levels were studied in a random, patient-blinded fashion. No details were provided regarding the intensity of pain required to be classified as positive. Structural abnormalities were for the most part ignored, but care was exercised in not allowing a leak through the outer anulus which the author thought would result in a false-positive response. At a minimum of 12 months, 34 of the 40 patients were available for follow-up. Using Odom’s criteria, ten patients (32%) had excellent results, 13 (38%) good, 4 patients (12%) fair, and 6 (18%) had poor results.

Finally, the frequent occurrence of multiple concordant painful levels may in fact be one of the most important uses of cervical discography because it often persuades the patient and surgeon not to pursue a surgical solution. Grubb and Kelly found that in patients with positive discography, 75% had two positive levels and 54% had three or more positive levels.³¹ Similarly, Parfenchuk and Janssen³⁴ found a 57% positive rate at multiple levels. Connor and Darden⁴³ found an 84% positive rate at multiple levels in 33 patients. Since many surgeons will not operate for discogenic pain when three or more levels are involved, these patients may be spared a potential failed surgery. In fact, of 173 patients studied by Grubb and Kelly, only 37 (20%) were felt to be surgical candidates. This high rate of multilevel positive responses supports a protocol of performing discograms on a minimum of four levels or on all accessible levels.³¹

Complications

All invasive tests have inherent risks. Placing a needle into a cervical disc has the potential to cause serious complications including infection, spinal cord injury, and bleeding. Because the disc is an avascular structure with poor defenses, infection should be and is the most common serious complication. Disc infections can spread to the adjacent epidural space and cause epidural abscess and cord compression. Cord injury can occur if the discographer passes a needle through the disc and into the spinal cord. Pressurizing a disc with contrast material or saline could potentially cause a disc herniation which could compromise the cord at a stenotic segment. Passing a needle through the carotid artery could potentially cause a plaque to be dislodged or significant bleeding that would cause airway compromise. The actual reported incidence of these potential serious complications is low.

Infection

In 1987, Fraser et al. inoculated sheep lumbar discs with contrast alone (control discs) and with contrast mixed with various concentrations of Staphylococcus epidermidis.⁴⁴ None of the control discs developed discitis. All of the discs inoculated with an estimated seven or more bacteria developed a bacterial discitis after 2 weeks. This report also included a review of human disc infection after discography using two different techniques. Discitis occurred in 2.7% of cases when discography was performed with a single large unstyletted needle. The discitis rate was only 0.7% when a double needle technique with styletted needles was employed. The authors concluded that ‘all cases of discitis after lumbar discography were initiated by infection, introduced by the needle tip.’ In a follow-up study, Osti et al. found no cases of disc space infection in 46 sheep discs inoculated with bacteria when either prophylactic antibiotics were given i.v. or mixed with the injected contrast.⁴⁵ In addition, the authors prospectively followed 127 consecutive patients undergoing lumbar discography using the styletted two-needle technique and with the addition of cephazolin at 1 mg per mL to the contrast material. None of the 127 patients developed any clinical or radiographic signs of discitis.

Contamination of a needle tip could occur from a cough or sneeze by the patient, operator, or support personnel, or contamination could occur by passage of the needle through a contaminated structure such as the esophagus, trachea, or hypopharynx. However, the most common reported causative organism in disc space infection is S. epidermidis and therefore the skin is probably the most common source of needle contamination.^46,⁴⁷ Mixed oropharyngeal flora have been isolated and there are case reports of subdural abscess⁴⁸ and retropharyngeal abscess.⁴⁹

Of the 1986 patients reported in case series,^43,^46,^47,^49,^50,⁵¹ 14 were found to have discitis, for an incidence of 0.7% per patient with a range of 0% to 3.2%. Zeidman et al.⁴⁷ reported the incidence of discitis in their study plus five other studies to be between 0.5% and 2%. Recently, Guyer et al.⁴⁹ reported two cases of discitis in 269 disc injections for an incidence of 0.74% per disc and 1.24% per patient. Prophylactic antibiotics were not routinely used. Both infected patients had a past medical history of diabetes mellitus. One case was found incidentally on a presurgical lateral X-ray film. In the other case, increased neck pain and arm pain were reported 3 days after cervical discography. Both patients had good clinical outcome with spontaneous fusion at the affected level.

Zeidman et al. have reported the largest series: 4400 disc injections in 1357 patients.⁴⁷ There were eight complications (seven cases of discitis and one retropharyngeal abscess) for an incidence of 0.18% infections per disc injection and 0.59% per patient. Prophylactic antibiotics were used in four out of the eight patients. They identified male gender, presence of a beard, and a short, thick neck as risk factors. All eight patients had good outcomes.

One case of discitis in 456 disc injections in 114 patients (0.22% per disc and 0.88% per patient) was reported by Simmons et al.⁴¹ Whitecloud and Seago identified one case of discitis out of 34 patients for an incidence of 0.296% per patient.⁴² In 1988, Guyer et al. reported two cases of cervical disc infection in 362 disc injections, for an incidence of 0.55% per disc.^46,⁴⁹ In 1993, Shinomiya and Segil documented no complications in 401 disc injections in 144 patients.²²

A report by Connor and Darden noted four complications in 31 patients for an incidence of 12.9%.⁴³ ‘Discitis’ reportedly occurred in one patient. Increased neck pain several days post-procedure preceded acute onset of tetraplegia 5 days after cervical discography. MRI indicated an anterior epidural mass from C3 to C7. Epidural abscess was suspected, but at surgery the mass was found to be firm, fibrous tissue. There was no purulent material; Gram stain revealed no bacteria and cultures were negative (personal chart review by C.A.). The patient was hypertensive, diabetic, and suffered with severe uncontrolled gout. The etiology of the fibrous anterior epidural mass is not clear.

Other complications included a patient with a severe vasovagal episode and one patient who had exacerbation of symptoms and was operated on several days after discography. It should be noted that it is normal to have residual discomfort for as long as 1 week following discography. Connors reported a complication rate 78% higher than the next highest series reporting complications. This difference could be the result of either marginal technique or incredibly bad luck.

Epidural abscess and miscellaneous rare complications

Smith and Kim reported an increase in the size of a disc herniation after cervical discography.⁵⁰ The patient had a past medical history of a moderate-sized central/left lateral herniated disc at C6–7. On injection of C6–7, the patient reported immediate severe concordant neck and arm pain. The following day, the patient had a temperature of 99.4°F orally, WBC of 12 700, ESR 55 mL per hour. Repeat ESR was 70 mL per hour. MRI obtained 18 hours after discography revealed fluid within the substance of an enlarged C6–7 disc herniation. Anterior corpectomy at C6 indicated thickened and a swollen posterior longitudinal ligament. Review of clinical history and MRI images is more suggestive of infection than an increased herniation size. The patient’s long-term outcome was good.

There are reports of paralysis/paresis after cervical discography. Lownie and Ferguson reported a case in which there was presentation of neck pain with bilateral radicular pain, low-grade temperature and progressive tetraparesis within 1 week of cervical discography.⁴⁸ The patient was found to have a subdural empyema from C5 to T12 and continued to have spastic paresis at 1-year follow-up. Eismont et al.⁵² reported a patient who had increased neck pain, weakness in all four extremities, and urinary incontinence 4 weeks after cervical discography. The patient had discitis with purulent encephalomeningitis, with continued tetraparesis at 5-year follow-up.

Laun et al. reported on two patients with paralysis related to discography; one with postinjection discitis and the other who developed tetraplegia within seconds of disc injection.⁵¹ Discography was contraindicated in both patients. The patient with discitis was found to have granulocytopenia and an intragluteal abscess premorbidly. The patient who suffered the immediate tetraplegia had a past medical history of myelopathy manifest by increased tone in all four extremities, weakness, and paresthesias. Premorbid myelogram showed arrest of contrast medium at the C4 disc space, confirming severe central stenosis. On injection, the patient reported excruciating pain. Within seconds, numbness and tetraparesis ensued. At surgery, one large and many small sequestered disc fragments were removed from the epidural space. In the discussion, one learns that the contrast was ‘injected very easily without exerting any pressure and was evenly distributed in the spinal canal.’ This statement raises the question of injection into the spinal cord. Regardless, cervical discography is contraindicated in a patient with cervical stenosis and myelopathy.

Minor complications were also reported by Guyer in 1997,⁴⁹ including headache and anterior cervical hematoma. Cervical hematomas causing airway obstruction have not been reported. Other theoretical but undocumented risks include pneumothorax when performing discography at C7–T1 or direct injection into the spinal cord.