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Background: Although numerous animal models for low back pain associated with intervertebral disk (IVD) degeneration have been proposed, insufficient data have been provided to make any conclusions regarding pain. Our aim in this study was to determine the reliability of complete Freund's adjuvant (CFA) injection into the rat spine as an animal model representing human discogenic pain., Methods: We studied IVD degenerative changes with pain development after a 10-microL CFA injection into the L5-6 IVD of adult rats using behavioral, histologic, and biochemical studies. Serial histologic changes were analyzed to detect degenerative changes. Expression of calcitonin gene-related peptide (CGRP), prostaglandin E (PGE), and inducible nitric oxide synthase (iNOS) were determined using immunohistochemistry or real-time polymerase chain reaction as support data for pain development. In addition, CGRP immunoreactivity (ir) at the IVD was considered indirect evidence of neural ingrowth into the IVD., Results: There was a significant increase of the hindpaw withdrawal response in the CFA group until 7 wk postoperatively (P < 0.05). Histologic analyses revealed progressive degenerative changes of the disks without any damage in adjacent structures, including nerve roots. In the CGRP-ir staining study, the bilateral dorsal horns and IVD had positive ir after intradiscal CFA injection. CGRP mRNA expression was increased in the dorsal root ganglion (DRG) at 2 and 4 wk, whereas PGE and iNOS mRNAs were markedly increased at 2 wk. The increment of CGRP expression was higher in allodynic rats compared with nonallodynic rats., Conclusion: Intradiscal CFA injection led to chronic disk degeneration with allodynia, which was suggested by pain behavior and expression of pain-related mediators. The increment of CGRP, PGE, and iNOS also suggest pain-related signal processing between the IVD and the neural pathway in this animal model. This animal model may be useful for future research related to the pathophysiology and development of novel treatment for spine-related pain.

Objective: To determine whether a patient's presenting psychometric scores affect the findings of a pressure and injection speed-controlled manometric lumbar diskography in patients with chronic low back pain (CLBP)., Design: A prospective, correlation-based, investigative study., Setting: Free-standing ambulatory spine surgery center., Participants: Two hundred sixty-three disks from 81 patients (54 men, 27 women)., Intervention: Diskography was performed using pressure and injection speed-controlled techniques. The patients were divided into psychometric subgroups (normal, at risk, abnormal) according to the Distress and Risk Assessment Method (DRAM)., Main Outcome Measures: The diskography findings on each psychometric DRAM subgroup were evaluated., Results: Across the individual psychometric categories, the positive rates of diskography in the normal, at-risk, and abnormal subgroups were 75.0% (9/12), 59.5% (25/42), and 70.4% (19/27), respectively (P>.05). The mean numeric rating scores of pain at 15 and 50 psi above the opening pressure were similar in the 3 psychometric subgroups. There was no correlation between the diskography results and the psychometric subgroupings., Conclusions: In patients with CLBP, there is no correlation between the presenting psychometric DRAM score and the findings from pressure and injection speed-controlled manometric lumbar diskography.

Background Context: Lumbar discography has been widely used to evaluate discogenic low back pain. Anecdotal evidence suggests that pain reproduction during discography is more closely correlated with peak dynamic pressure than with static postinjection pressure. Although there can be a significant difference between dynamic and static pressures, to date most discographic evaluations use static pressure recorded postinjection (which is stable and easily measured). The use of readings taken after injection, rather than readings of maximum dynamic peak pressure recorded during injection, appear to increase false positives in lumbar discography. High-speed intradiscal injections also appear to have potentially confounding effects that may increase the rate of false-positive responses during lumbar discography. To date there has been no study for the evaluation of peak dynamic intradiscal pressures or for differentiating dynamic from static pressures in the nucleus pulposus (NP) in response to various speeds of intradiscal injection., Purpose: The goal of this study was to obtain additional data on potential confounding factors that could affect discographic results by assessment of pressures within the NP during discography at various injection speeds. The purpose of data collection was to more precisely evaluate pressure differences between dynamic and static pressure within the NP, evident during discography., Study Design: In vitro laboratory study., Samples: A total of 82 trials were performed on intervening discs of 82 porcine cadaver lumbar spines., Methods: Dynamic and static intradiscal pressures were measured with manometry, using two pressure sensors simultaneously during intradiscal injection of contrast media at various speeds. The tip of a 25-gauge needle was placed in the center of the NP and connected with a pressure manometer, which recorded the pressure and therefore the speed of injection. A second pressure reading was obtained using a sensor tip connected to a transducer; the sensor tip was located separately in the same NP tissue. The needle and transducer locations were confirmed by fluoroscopy., Outcome Measures: At low controlled injection speeds (below 0.08 mL/s), the mean peak pressure difference in the NP was 4.06 (+/-1.52) psi. With high-speed injections of 0.08 mL/s or greater, the mean increased abruptly up to 14.52 (+/-4.11) psi (p<.05). The data indicate that injections applied slowly resulted in smaller differences in pressure within the NP, registered by both manometry and the needle sensor tip. Additional samples were taken using both devices to confirm this threshold level., Results: With low injection speeds, especially those below 0.08 mL/s, differences between dynamic and static pressures on both pressure sensors were minor. These differences increased as injection speed became faster. However, at fast injection speeds of 0.08 mL/s and above, those differences were significantly higher., Conclusion: Dynamic and static intradiscal pressures are of similar value when measured by manometer and by needle sensor at slow injection speeds during discography. However, the pressure differences appeared to rapidly increase in response to incremental increases in injection speed. The data from these 82 samples suggest that uncontrolled high speeds of intradiscal injections are a potential confounding factor, which may increase false-positive responses during lumbar discography.

Although it entails a radiation hazard risk, the use of fluoroscopy during caudal epidural steroid injection has increased to help place the medication more accurately and allowed physicians to maximize the procedure's therapeutic success rate. To investigate the feasibility of using real-time high resolution ultrasonography for guiding the epidural needle into the caudal epidural space and to confirm any vascular intake of medication, we performed color Doppler ultrasonography while medication was being injected into the caudal epidural space of 53 patients with low back pain and sciatica. We defined the injection as being successful if unidirectional flow (observed as one dominant color) of the solution was observed with color Doppler ultrasonography through the epidural space beneath the sacrococcygeal ligament, with no flows being observed in other directions (observed as multiple colors). The correct placement of the medication was then confirmed by fluoroscopy. In 52 of the 53 subjects, the medications were successfully injected into the caudal epidural space with ultrasonography assistance. In fluoroscopy, of these 52 patients, 50 revealed correct placement of the medicine into the epidural space. In conclusion, ultrasonography may be a reliable imaging modality for caudal epidural steroid injection, and its several advantages such as its convenience and the lack of a radiation hazard, make it preferable to fluoroscopy.

Object: The authors examined the effect of psychological and emotional status on the outcome in patients with suspected chronic discogenic low-back pain (LBP) who have undergone lumbar fusion., Methods: The authors retrospectively analyzed the medical records, including the results of the 36-item Short Form (SF-36), of 57 consecutive patients (mean age 42.7 years) who underwent single-level lumbar reconstructive surgery between 1994 and 2000. The SF-36 physical component summary (PCS) and mental component summary (MCS) domains were evaluated. Data were sorted into the following categories: excellent, good, fair, same, and worse. Scores greater than 40 for MCS and PCS were defined as "normal" according to US general population data provided by the Medical Outcomes Trust. Of 57 patients, 47 completed postoperative SF-36 surveys at 1 year and 36 completed the 2-year follow-up surveys. Analysis showed that preoperative MCS scores exhibited a significant, direct correlation with PCS score improvements at 1 (r = 0.584, p = 0.000) and 2 (r = 0.623, p = 0.000) years after surgery. In patients in whom preoperative MCS scores reflected normal status, outcomes were excellent or good in 60% at 1-year (18 of 30 cases) and 2-year (15 of 25 cases) follow-up intervals. Patients in whom MCS scores represented abnormal status had less satisfactory outcomes, with excellent or good outcome in only two (18.2%) of all patients at the 2-year follow-up study., Conclusions: Analysis of the data suggests that psychological and emotional distress may negatively affect postoperative outcome in patients with chronic discogenic LBP. The SF-36 may be easily and effectively used to measure both preoperative psychosocial distress and postoperative outcome.

Objective: To analyze the relation between annular disruption determined by computed tomography (CT) scan and diskographic findings using pressure-controlled manometric diskography., Design: Cross-sectional using prospectively gathered data., Setting: Ambulatory spine intervention unit., Specimens: Two hundred seventy-nine disks from 86 patients (55 men, 31 women) who were referred for diskography of suspected chronic diskogenic low back pain., Interventions: Not applicable., Main Outcome Measures: The grade of annular disruption was rated using CT diskography and fluoroscopic imaging as follows: 0 (no disruption); 1 (extension into the inner third of the annulus); 2 (extension into the middle third of the annulus); 3 (extension into the outer third of the annulus); 4 (circumferential extension with a >30 degrees arc at the disk center); and 5 (contrast media leakage into the outer space). Diskography was performed via a pressure-controlled manometric technique using an injection rate of .05 mL/s and a restricted total volume of 3.5 mL. Pain was rated on a 0 to 10 numeric rating scale (NRS). Criteria for symptomatic disks included provocation of patient concordant pain (NRS score, > or =6/10) at 50psi or less above opening pressure, with 3.5 mL or less of total volume. Symptomatic disks were classified as "low pressure sensitive" or "high pressure sensitive" based on the pressure level that evoked pain. Disks classified as low pressure sensitive required an NRS score of 6 out of 10 or higher at 15 psi or less above opening pressure. Disks classified as high pressure sensitive required an NRS score of 6 out of 10 or higher at pressures within a range of 15 to 50 psi., Results: The numbers of disks at each annular disruption grade were 19 (6.8%) at grade 0, 29 (10.4%) at grade 1, 35 (12.5%) at grade 2, 42 (15.1%) at grade 3, 69 (24.7%) at grade 4, and 85 (30.5%) at grade 5. A total of 93 disks met the criteria for a symptomatic disk. The extent of annular disruption and the rate of symptomatic disks correlated significantly (P<.001). The highest symptomatic disk rate was observed in grade 4 disks. Of 93 symptomatic disks, 88 (94.6%) showed annular disruption of grade 3 or greater. Disks with grades 0 to 2 and grades 3 to 5 annular disruption differed significantly when the mean NRS relative to intradiskal pressure was compared (P<.001). Comparing the disk type of symptomatic disks at each annular disruption grade, there was a decreasing trend of low pressure sensitive disks relative to the extent of annular disruption (62.5% at grade 3, 39.4% at grade 4, 34.2% at grade 5)., Conclusions: Annular disruption reaching the outer annulus fibrosus is a key factor in pain generation. Disk morphology, including annular disruptions extending beyond the outer annulus, may permit increased diskography specificity.

Background Context: Lumbar discography has been widely used for evaluating discogenic low back pain (LBP). Comparison of pain responses from suspected symptomatic discs with pain responses from asymptomatic negative discs is routine. However, the ability of discography to distinguish asymptomatic morphologically abnormal discs from those that are symptomatic has been understudied. In addition, the discographic characteristics of negative discs in patients with chronic discogenic LBP have not been reported. Criteria for negative morphologically abnormal discs may be valuable for excluding discs from further treatment and examination., Purpose: To determine if discography can distinguish asymptomatic discs among morphologically abnormal discs in patients with suspected chronic discogenic LBP and establish the standard characteristics of negative discs., Study Design/setting: Prospective, experimental with control group., Patient Sample: Fifty-five discs from a control group of 16 healthy volunteers without current back pain (11 men, 5 women, 32-61 years of age, mean age: 47 years) and 282 discs from a patient group of 90 LBP patients (59 men, 31 women, 20-70 years of age, mean age: 44.7 years) were recruited., Methods: Discography was performed using a pressure-controlled manometric technique with an injection rate of 0.05 mL/s and a 3.5 mL restricted total volume. Concordance was rated as none/unfamiliar, or familiar. Pain was rated via a 0-10 numerical rating scale (NRS). The pressure and volume at which pain was evoked and NRS pain responses at 15, 30, and 50 psi were recorded. Annular disruption grade was rated during the procedure by computed tomography discography and fluoroscopic imaging. Negative discogram required no pain described by the participant as "familiar," with no pain responses >or=6/10 NRS at pressures

Background Context: Intradiscal electrothermal annuloplasty (IDET) is a minimally invasive procedure for managing chronic discogenic low back pain (LBP). Although there have been numerous reports of IDET outcome rates, few have dissected the detailed factors affecting those outcomes., Purpose: To evaluate how heating variables and the number of catheters used affect the outcomes and pain flare-up in LBP patients treated with IDET., Study Design/setting: Retrospective analysis., Patient Sample: Data were gathered on the basis of chart records from January 6, 1999 to January 6, 2000. Twenty-five cases treated at a single level with disc protrusion < or = 2 mm, nonfocal neurological abnormalities, and positive discogram with annular tear were studied. Six patients were unavailable for follow-up at 16 months., Outcome Measures: All assessments were incorporated into our own evaluation sheet, completed before the procedure and at follow-up. Assessments included the following: 1) Visual Analog Scale (VAS) and 2) Back Pain Improvement Scales (BPI) preoperatively and at 8 and 16 months post-procedure. Post-procedure flare-up of the pain was defined as the pain aggravation after the IDET procedure from the pre-procedure baseline pain. It was evaluated by a 10-point numeric rating scale, ranging from no aggravated pain "0" to the worst aggravated pain "10"., Methods: Patients were partitioned into a single-catheter group and a double-catheter group. In these two groups, statistical analyses were done to compare the outcomes and flare-up duration and intensity. In each catheter group, the correlation coefficients were analyzed between heating variables such as heating duration/temperature and two outcome scales. Then, two outcome scales relative to intensity and duration of post-IDET flare-up were analyzed with Pearson's correlation. Also the combined effect of the heating duration and temperature was evaluated as a thermal dosage, which is the total amount of heat developed during the procedure. It was calculated by multiplying the temperature and its heating duration above a starting temperature of 65 degrees C., Results: Comparing the single- and double-catheter groups, patients placed in the single-catheter group showed significantly shorter flare-up duration (11.00+/-19.17 vs. 24.89+/-20.84 days, p < .05). In the single-catheter group, the flare-up duration manifested moderate linear correlation with heating variables (0.580 with temperature, 0.519 with thermal dosage, p < .05). Also, the improvements of pain with VAS displayed moderate reverse correlation with heating variables at 8 months (-.436 with temperature, -0.439 with thermal dosage, p < .1). In the double-catheter group, the Back Pain Improvement% had strong reverse correlations with temperature and thermal dosage at 8 months (-.735 and -.729, p < .05). The correlation between the improvement of VAS and temperature yielded a moderate reverse relationship (-.619, p < 0.1). These correlations were not, however, observed at 16 months in either the single- or double-catheter groups., Conclusions: Higher temperatures and larger total heating doses during IDET procedures with catheters placed in the outer annulus may increase the duration of post-procedure pain flare-ups and lead to less favorable outcomes at 8 months follow-up. The long-term outcomes at 16 months may, however, not be affected by these heating variables.

Study Design: Retrospective outcome measurement after circumferential reconstructive surgery with lumbar fusion in patients with chronic discogenic low back pain., Objective: To examine the effect of the number of fusion levels on surgical outcomes in patients with chronic discogenic low back pain using provocative pressure-controlled diskography as a primary diagnostic tool., Summary of Background Data: Although there is general agreement that construct length adversely affects arthrodesis success rates, the effect of the number of levels on lumbar fusion surgery outcome has not been reported. Previous fusion outcome studies have generally relied on magnetic resonance imaging or conventional diskography for diagnosis., Methods: From 1994 through 2000, prospectively collected medical records of patients who underwent reconstructive lumbar spine surgery with confirmation of the pain generator by pressure-controlled diskography were retrospectively analyzed. Data were subdivided into 2 groups of patients. The first group, designated the short segment group, contained patients who underwent fusion at 1 or 2 levels. The second group, designated the long segment group, contained patients who underwent fusion at 3-5 levels. Surgical methods included circumferential reconstruction of the lumbar spine by either posterior or combined anterior and posterior approach. Surgeries included posterior decompression necessary to relieve documented regions of neural compression, combined with interbody arthrodesis at selective levels, augmented by posterior segmental spinal instrumentation and posterolateral arthrodesis. All patients completed a preoperative aquatic-conditioning program. Whenever possible, coexisting medical conditions were corrected or stabilized before surgery. A preoperative Short Form RAND 36-Item Health Survey (SF-36) was completed, and repeated at 1 and 2 years after surgery. The short and long segment groups contained 142 and 82 patients, respectively, who completed the preoperative SF-36 questionnaire completely., Results: One hundred patients in the short segment group (vide infra) were available for 1-year follow-up, and68 were available for 2-year follow-up. In the long segment group, 81 patients were available for 1-year follow-up, and 49 were available for 2-year follow-up. Mean ages were 41.0 and 47.6 years in the short and the long segment groups, respectively. The 2 groups did not differ significantly in gender, smoking habits, workers' compensation, or litigation (P > 0.05). In the short segment group, postoperative 1-year mean Physical Component Summary (PCS) and Mental Component Summary scores significantly improved (P < 0.001 and P = 0.002, respectively). Domains other than general health perceptions showed significantly improved 1-year follow-up scores (P 0.05), although the PF score showed differences in 1 and 2-year follow-up scores (P = 0.048 and P = 0.068, respectively)., Conclusions: When using strict patient selection criteria that include independent determination of pain generators via pressure-controlled diskography and completion of a preoperative conditioning program for improving general health status, the number of levels in reconstructive lumbar surgery may not significantly impact overall clinical outcome.