ORIGINAL ARTICLE
Does Improvement in Epidurography Following Percutaneous Epidural Neuroplasty Correspond to Patient Outcome? Jae Hun Kim, MD*; Hee Jin Jung, MD†; Francis Sahngun Nahm, MD‡; Pyung Bok Lee, MD, PhD‡ *Department of Anesthesiology and Pain Medicine, Konkuk University Medical Center, Seoul; Department of Anesthesiology and Pain Medicine, Armed Forces Capital Hospital, Seongnam; ‡ Department of Anesthesiology and Pain Medicine, Seoul National University Bundang Hospital, Seongnam, Korea
†
& Abstract Objective: The positive effects of percutaneous epidural neuroplasty (PEN) likely result from elimination of fibrous tissue. However, a direct link between epidural adhesions and pain symptoms is debatable. We tested the hypothesis that epidurographic improvements correspond to improved patient outcome. Methods: In this prospective study, patients with a filling defect on initial epidurography underwent PEN. Two weeks later, contrast agent distribution around the target area was assessed with repeat epidurography. A successful treatment was defined as over a 50% reduction in visual analog scale (VAS) score 2 weeks postprocedure. The demographic data, history of lumbar spine operation, target nerve, diagnosis, VAS scores, degree of epidurographic improvement, and patient satisfaction were compared between the successful treatment group (Group I) and unsuccessful treatment group (Group II).
Results: Seventy-nine patients were included. Epidurographic findings improved in 67.1% of patients 2 weeks after the procedure. Following PEN, the mean VAS scores of all patients were significantly decreased at 2 weeks (4.12 2.34), 1 month (3.56 2.30), 3 months (3.84 2.45), and 6 months (4.13 2.71) compared with the initial scores (7.82 1.78). In the comparison between Groups I and II, the rate of epidurographic improvement in Group I was higher than in Group II (P = 0.022). Satisfaction in patients that had epidurographic improvement (median satisfaction: 4) was higher than in patients that did not have epidurographic improvement (median satisfaction: 3; P = 0.003). Conclusion: The epidurographic changes following PEN correlate with patient-assessed pain relief and satisfaction. & Key Words: epidurography, epidural injections, epidural neuroplasty, low back pain, treatment outcome
INTRODUCTION Address correspondence reprint requests to: Pyung Bok Lee, MD, PhD, Department of Anesthesiology and Pain Medicine, Seoul National University Bundang Hospital, 166, Gumi-ro, Bundang-gu, Seongnam 463-707, Korea. E-mail: [email protected]. Submitted: October 15, 2013; Revised: December 26, 2013; Revision accepted: January 27, 2014 DOI. 10.1111/papr.12197
© 2014 World Institute of Pain, 1530-7085/14/$15.00 Pain Practice, Volume 15, Issue 5, 2015 407–413
Low back pain and/or lower extremity pain is a common problem that is sometimes difficult to treat. In chronic refractory low back pain and/or radicular pain, interventional pain management by percutaneous epidural neuroplasty (PEN) is a favorable treatment method.1 The effects of percutaneous epidural neuroplasty are believed to result from adhesiolysis or decompression of the involved nerve root, which leads to improved
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targeting of drug delivery and subsequent therapeutic effects.2–5 However, whether or not epidural adhesion is the cause of pain is still under debate.6–12 Epidural fibrosis can occur not only after spinal surgery, but also as a result of infection, hematoma, annular tears, intrathecal contrast media, or herniated intervertebral disks.13,14 The resulting adhesions may cause mechanical compression or chemical reaction in the nerve, which are associated with low back pain and/or radicular pain. This study investigates the use of epidurography in the assessment of epidural adhesions pre- and postneuroplasty and evaluates the relationship between postPEN epidurographic change and patient outcome. If an epidurographic filling defect correlates with the symptoms, it is meaningful for the clinical diagnosis. It is thought that if the improvement in epidural adhesion after epidural neuroplasty is associated with an improvement in patient symptoms, the adhesion plays a role in the pain. We tested the hypothesis that epidurographic improvement following PEN is related to patient outcome.
METHODS After obtaining the approval of our institutional review board (IRB No. B-1007/106-106), we performed a prospective study in our hospital from June 2007 to December 2010. Patients that had been diagnosed with spinal stenosis or herniated intervertebral disk by L-spine MRI and that experienced transient (< 2 weeks) or no relief from epidural block, pharmacotherapy, and exercise underwent epidurography. They were included in the study if epidurography showed a filling defect corresponding to the symptom level and the abnormality on L-spine MRI, and they subsequently underwent PEN. The data of patient’s age, height, weight, sex, history of lumbar spine operation, side of major symptom (left or right), target nerve, diagnosis, visual analog scale (VAS) scores, improvement in epidurographic filling defect, and patient satisfaction were collected. To determine the effect of treatment, the 10-cm VAS score—0 being no pain and 10 being the most severe pain—was administered prior to the PEN, and at 2 weeks, 1 month, 3 months, and 6 months postneuroplasty. The satisfaction was rated using a 5-point Likert scale: 1 = very unsatisfactory, 2 = unsatisfactory, 3 = neutral, 4 = satisfactory, and 5 = very satisfactory. For epidurography, the tip of an epidural needle was positioned at the level of the center of the S3 foramen, and 20 mL of
contrast media (OMNIPAQUETM; GE Healthcare, Waukesha, Wl, USA) was injected under fluoroscopic guidance.15–17 PEN was performed using the Racz catheter. Exclusion criteria were age under 20 years, lack of informed consent, coagulopathy, pregnancy, active infection at the injection site, or allergic reaction to injected materials for epidural neuroplasty. An RK needle was inserted into the epidural space through the sacral hiatus under fluoroscopic guidance. Then, the Racz catheter was introduced and its tip positioned close to the filling defect, that is, at the level of the symptomatic nerve. After 2 mL of contrast media was administered under continuous fluoroscopic guidance, its distribution in the epidural space and absence of spread to the intravascular, subdural, or intrathecal spaces were confirmed. Hyaluronidase (1,500 units; H-laseâ, Kuhnil Pham, Korea) was administered through the indwelling catheter. The patient was subsequently taken out of the theater and returned to the ward, and 8 mL of 1% mepivacaine was injected via the catheter in split doses of 0.5 to 1 mL at 5-minute intervals. After 20 minute, if no motor weakness or other complications were evident, 8 mL of 10% hypertonic saline was injected in the same manner. On the second day, 8 mL of 1% mepivacaine mixed with 40 mg of triamcinolone and 8 mL of 10% hypertonic saline were injected through the indwelling catheter. On the third day, the protocol was completed with injection of 8 mL of 1% mepivacaine and the catheter was removed (Figure 1). After 2 weeks, a second epidurography was conducted to assess any change in epidural filling defects. Epidurograms of each patient (pre- and postprocedure anteroposterior [AP] views) were analyzed by a radiologist and an experienced pain clinician, who were not involved the procedures and were only aware of the spinal level to be investigated. The analysis of epidurograms was categorized as “improvement” or “no improvement.” Epidurographic improvement at the symptomatic level was defined as postprocedure contrast extending farther than preprocedure contrast in anteroposterior views (Figure 2). When the analyses differed, a second radiologist assessed the epidurograms and a consensus was reached. A successful treatment after 2 weeks was defined as over a 50% reduction in VAS score postprocedure. These cases comprised Group I. The cases with a reduction of < 50% in VAS score postprocedure comprised Group II. The demographic data, history of lumbar spine operation, side of major symptom, target nerve, diagnosis, degree of epidurographic improvement, and patient
Epidurographic Improvement in Epidural Neuroplasty 409
Figure 1. Schematic protocol of the study. HIVD, herniated intervertebral disk.
satisfaction were compared between Group I and Group II. The mean differences were analyzed using Student’s t-test or analysis of variance (ANOVA). The proportional differences were evaluated using a chi-square test. P values < 0.05 were considered statistically significant.
RESULTS In total, 79 patients were enrolled in this study. The demographic data are presented in Table 1. Following PEN, 53 patients (67.1%) displayed epidurographic improvement in the filling defect 2 weeks after the procedure. Following PEN, the mean VAS scores of all patients significantly decreased at 2 weeks (4.12 2.34),
1 month (3.56 2.30), 3 months (3.84 2.45), and 6 months (4.13 2.71) compared with the initial scores (7.82 1.78; Figure 3). Two weeks after PEN, Group I comprised 45 patients and Group II comprised 34 patients. There were no significant differences in the demographic data (sex [P = 0.972], age [P = 0.733], height [P = 0.457], and weight [P = 0.945]), pain side (right or left; P = 0.538), associated nerve (L4, 5 or S1; P = 0.941), diagnosis (P = 0.836), history of lumbar spine operation (P = 0.509), or initial VAS scores (7.88 1.74, 7.77 1.85; P = 0.803) between the 2 groups (Table 2). However, the rate of epidurographic improvement in Group I was higher than that in Group II (P = 0.022, 95% confidence interval: 0.121 to 0.851).
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A
B
Figure 2. Initial epidurography (A) and second epidurography (B) 1 week after percutaneous epidural neuroplasty (PEN). This patient had a spine surgery history and displayed left S1 root symptoms and left S1 and S2 area filling defects on the epidurogram (A). Following the procedure, the contrast material distributed to the left side of S1 (B).
Table 1. Demographic Data No. of Patients Sex (M/F) Age (years) Height (cm) Weight (kg) Side of major symptom (Right/Left) Nerve of major symptom L4 L5 S1 Diagnosis Spinal stenosis Herniated intervertebral disk
Table 2. Demographic Data in the Groups I and II 79 37/42 64.5 11.6 161.0 9.4 62.9 8.9 41/38 5 71 3 69 10
M, male; F, female.
No. of patients Sex (M/F) Age (yrs) Height Weight (kg) Side of major symptoms (Right/Left) Nerve of major symptoms L4 L5 S1 Diagnosis Spinal stenosis Herniated intervertebral disk History of lumbar spine operation No. of epidurographic improvement* Median satisfaction*
Group I
Group II
45 (57%) 24/21 64.2 12.0 160.4 9.3 62.8 8.9 22/23
34 (43%) 18/16 65.14 13.95 162.0 9.5 63.0 9.0 19/15
2 39 4
1 30 3
39 6
30 4
14 (31%)
13 (38%)
35 (78%)
18 (53%)
4
3
M, male; F, female; Group I, the patients who had over a 50% reduction in VAS score pre- to postprocedure after 2 weeks; Group II, the patients who had under a 50% reduction in VAS score pre- to postprocedure after 2 weeks. Values are the mean SD. Satisfaction scale: 1 = very unsatisfactory, 2 = unsatisfactory, 3 = neutral, 4 = satisfactory, 5 = very satisfactory. *P < 0.05.
tion: 4) was higher than in patients who did not show epidurographic improvement (median satisfaction: 3; P = 0.003).
DISCUSSION Figure 3. VAS changes for 6 months. *P < 0.05, between initial VAS and each period. VAS, visual analog scale.
Satisfaction in Group I (median satisfaction: 4) was also higher than that in Group II (median satisfaction: 3; P = 0.001; Table 2). Satisfaction in patients who showed epidurographic improvement (median satisfac-
In this study, 67.1% of patients had epidurographic improvement at the PEN treatment level. This study demonstrates that improvements seen on epidurography correspond with improvements in pain score and patient satisfaction. Therefore, PEN may remove some epidural adhesions, and this may be an important factor in successful treatment.
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Percutaneous epidural neuroplasty operates on the premise that epidural adhesions are the cause of symptoms in patients with low back and/or lower extremity pain. Several reports have investigated the relationship between epidural adhesions and pain. Some of these studies confirm that patients displaying scars or adhesions suffer more from severe pain.6,18–22 Other studies have questioned whether epidural adhesions are the cause of pain,9,10,23,24 and some surgeons insist that PEN cannot remove the adhesions. However, as seen in our results, most studies have shown that PEN is an effective treatment of low back pain and/or radicular pain.4,25–29 Rydell et al. described the grade of fibrosis/ adhesion (grade 0 = no significant adhesions, grade 1 = the adhesions formed were thin, sparse, and easily broken, grade 2 = the adhesions were more dense, but could be disrupted with dissection, grade 3 = the adhesions were so dense that they had to be cut with a knife).30 In that description, grade 3 adhesions may be too thick to improve with PEN. Grade 1 or 2 adhesions may respond to PEN. Further investigations of the relationship between grade of fibrosis/adhesion and PEN effectiveness are needed. Although MRI can identify some epidural fibrosis,10,23 surgery and epiduroscopy often show fibrosis that MRI underestimates or misses entirely.18,31,32 In our experience, epidurography can depict a filling defect associated with epidural adhesion in patients with negative MRI findings. Therefore, epidurography shows potential as a sensitive method for detecting epidural adhesions.33 In addition, epidurography is less expensive than MRI and can be readily performed by pain physicians. In 1 study related to epidurographic improvement and pain score,15 14 of 30 (46.7%) patients displayed an epidurographic improvement in contrast spread at the end of the third day after PEN, but this improvement was not related to improved pain behavior. The neuroplasty technique used in this study differed from our study, as the catheter tip was not placed at the symptomatic filling defect area. Therefore, the epidurographic improvement may not have been directly related to the symptomatic improvement, and the lack of correlation between the epidurogram and pain score may not have represented a true effect. In our study of 79 patients, improvements in epidural adhesion following PEN using the Racz catheter were seen in 53 (67.1%) of the 79 patients at 2 weeks following the procedure. We placed the catheter tip at the symptomatic epidural filling defect, and confirmation of epidu-
rographic improvement was limited to the area around the symptomatic nerve area. As epidurographic improvement was related to patients’ outcome, it seems likely that adhesions can cause symptoms that are relieved by neuroplasty. Adhesion formation occurs as a result of epidural perineural fibrosis in which collagen fibers surround the nerve tissue causing lateral spinal stenosis, interrupting arterial perfusion and venous return.34 Although perineural fibrosis is not intrinsically painful, it can lead to mechanical tethering of the dura mater and nerve roots, and interference with nutritional delivery via cerebrospinal fluid. These changes sensitize the nerve root to pressure, which can eventually lead to chronic low back pain.6,13,35 There are some limitations in this study, as only the relationship between the improvement in symptoms and the epidurographic assessment of adhesions after 2 weeks was investigated. A longer follow-up period would provide additional information. In this study, the epidurograms were evaluated by considering the presence or absence of improvement. No validated grading system has been established for the epidurographic assessment of epidural adhesions. If the improvement could be graded, it may be more useful in the prediction of treatment effect and prognosis. A control group receiving mepivacaine and triamcinolone alone and groups with discordant pain levels and epidurographic findings were not included. In conclusion, this study shows that PEN is a promising method for patients who have epidurographic filling defects associated with refractory symptoms, and successful PEN is associated with epidurographic improvement. Although not all epidural adhesions may cause pain, adhesions related to the symptoms can represent a treatment target for PEN.
REFERENCES 1. Epter RS, Helm S 2nd, Hayek SM, Benyamin RM, Smith HS, Abdi S. Systematic review of percutaneous adhesiolysis and management of chronic low back pain in post lumbar surgery syndrome. Pain Physician. 2009;12:361–378. 2. Takeshima N, Miyakawa H, Okuda K, et al. Evaluation of the therapeutic results of epiduroscopic adhesiolysis for failed back surgery syndrome. Br J Anaesth. 2009;102:400–407. 3. Igarashi T, Hirabayashi Y, Seo N, Saitoh K, Fukuda H, Suzuki H. Lysis of adhesions and epidural injection of steroid/ local anaesthetic during epiduroscopy potentially alleviate low back and leg pain in elderly patients with lumbar spinal stenosis. Br J Anaesth. 2004;93:181–187.
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4. Trescot AM, Chopra P, Abdi S, Datta S, Schultz DM. Systematic review of effectiveness and complications of adhesiolysis in the management of chronic spinal pain: an update. Pain Physician. 2007;10:129–146. 5. Manchikanti L, Rivera JJ, Pampati V, et al. One day lumbar epidural adhesiolysis and hypertonic saline neurolysis in treatment of chronic low back pain: a randomized, doubleblind trial. Pain Physician. 2004;7:177–186. 6. Ross JS, Robertson JT, Frederickson RC, et al. Association between peridural scar and recurrent radicular pain after lumbar discectomy: magnetic resonance evaluation. ADCON-L European Study Group. Neurosurgery. 1996;38:855–861; discussion 861–853. 7. Hoyland JA, Freemont AJ, Jayson MI. Intervertebral foramen venous obstruction. A cause of periradicular fibrosis?. Spine (Phila Pa 1976). 1989;14:558–568. 8. Dullerud R, Graver V, Haakonsen M, Haaland AK, Loeb M, Magnaes B. Influence of fibrinolytic factors on scar formation after lumbar discectomy. A magnetic resonance imaging follow-up study with clinical correlation performed 7 years after surgery. Spine (Phila Pa 1976). 1998;23:1464– 1469. 9. Cervellini P, Curri D, Volpin L, Bernardi L, Pinna V, Benedetti A. Computed tomography of epidural fibrosis after discectomy: a comparison between symptomatic and asymptomatic patients. Neurosurgery. 1988;23:710–713. 10. Coskun E, Suzer T, Topuz O, Zencir M, Pakdemirli E, Tahta K. Relationships between epidural fibrosis, pain, disability, and psychological factors after lumbar disc surgery. Eur Spine J. 2000;9:218–223. 11. Jo DH, Jang S. The correlation between caudal epidurogram and low back pain. Korean J Pain. 2012;25:22–27. 12. Shin JW. Is epidurogram a reliable tool for the diagnosis of epidural adhesion? Korean J Pain. 2012;25:133– 134. 13. Chopra P, Smith HS, Deer TR, Bowman RC. Role of adhesiolysis in the management of chronic spinal pain: a systematic review of effectiveness and complications. Pain Physician. 2005;8:87–100. 14. Cooper RG, Freemont AJ, Hoyland JA, et al. Herniated intervertebral disc-associated periradicular fibrosis and vascular abnormalities occur without inflammatory cell infiltration. Spine (Phila Pa 1976). 1995;20:591–598. 15. Devulder J, Bogaert L, Castille F, Moerman A, Rolly G. Relevance of epidurography and epidural adhesiolysis in chronic failed back surgery patients. Clin J Pain. 1995;11:147–150. 16. Cleary M, Keating C, Poynton AR. The flow patterns of caudal epidural in upper lumbar spinal pathology. Eur Spine J. 2011;20:804–807. 17. Kim KM, Kim HS, Choi KH, Ahn WS. Cephalic spreading levels after volumetric caudal epidural injections in chronic low back pain. J Korean Med Sci. 2001;16:193–197. 18. Ido K, Urushidani H. Fibrous adhesive entrapment of lumbosacral nerve roots as a cause of sciatica. Spinal Cord. 2001;39:269–273.
19. de Tribolet N, Porchet F, Lutz TW, et al. Clinical assessment of a novel antiadhesion barrier gel: prospective, randomized, multicenter, clinical trial of ADCON-L to inhibit postoperative peridural fibrosis and related symptoms after lumbar discectomy. Am J Orthop (Belle Mead NJ). 1998;27:111–120. 20. Ross JS, Obuchowski N, Modic MT. MR evaluation of epidural fibrosis: proposed grading system with intra- and inter-observer variability. Neurol Res. 1999;21(suppl 1):S23– S26. 21. BenDebba M, Augustus van Alphen H, Long DM. Association between peridural scar and activity-related pain after lumbar discectomy. Neurol Res. 1999;21(Suppl 1):S37– S42. 22. Kroin JS, Buvanendran A, Cochran E, Tuman KJ. Characterization of pain and pharmacologic responses in an animal model of lumbar adhesive arachnoiditis. Spine (Phila Pa 1976). 2005;30:1828–1831. 23. Ronnberg K, Lind B, Zoega B, et al. Peridural scar and its relation to clinical outcome: a randomised study on surgically treated lumbar disc herniation patients. Eur Spine J. 2008;17:1714–1720. 24. Annertz M, Jonsson B, Stromqvist B, Holtas S. No relationship between epidural fibrosis and sciatica in the lumbar postdiscectomy syndrome. A study with contrastenhanced magnetic resonance imaging in symptomatic and asymptomatic patients. Spine (Phila Pa 1976). 1995;20:449– 453. 25. Manchikanti L, Boswell MV, Singh V, et al. Comprehensive evidence-based guidelines for interventional techniques in the management of chronic spinal pain. Pain Physician. 2009a;12:699–802. 26. Manchikanti L, Boswell MV, Datta S, et al. Comprehensive review of therapeutic interventions in managing chronic spinal pain. Pain Physician. 2009b;12:E123–E198. 27. Van Boxem K, Cheng J, Patijn J, et al. 11. Lumbosacral radicular pain. Pain Pract. 2010;10:339–358. 28. de Tran QH, Duong S, Finlayson RJ. Lumbar spinal stenosis: a brief review of the nonsurgical management. Can J Anaesth. 2010;57:694–703. 29. Park CH, Lee SH. Effectiveness of percutaneous transforaminal adhesiolysis in patients with lumbar neuroforaminal spinal stenosis. Pain Physician. 2013;16:E37–E43. 30. Rydell N, Balazs EA. Effect of intra-articular injection of hyaluronic acid on the clinical symptoms of osteoarthritis and on granulation tissue formation. Clin Orthop Relat Res. 1971;80:25–32. 31. Ruetten S, Meyer O, Godolias G. Epiduroscopic diagnosis and treatment of epidural adhesions in chronic back pain syndrome of patients with previous surgical treatment: first results of 31 interventions. Z Orthop Ihre Grenzgeb. 2002;140:171–175. 32. Saitoh K, Igarashi T, Hirabayashi Y, et al. Epiduroscopy in patients with chronic low back pain without remarkable findings on magnetic resonance imaging. Masui. 2001;50:1257–1259.
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33. Manchikanti L, Bakhit CE. Percutaneous lysis of epidural adhesions. Pain Physician. 2000;3:46–64. 34. 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 (Phila Pa 1976). 1987;12:760–764. 35. Rydevik BL. The effects of compression on the physiology of nerve roots. J Manipulative Physiol Ther. 1992;15:62–66.
Does Improvement in Epidurography Following Percutaneous Epidural Neuroplasty Correspond to Patient Outcome? Jae Hun Kim, MD*; Hee Jin Jung, MD†; Francis Sahngun Nahm, MD‡; Pyung Bok Lee, MD, PhD‡ *Department of Anesthesiology and Pain Medicine, Konkuk University Medical Center, Seoul; Department of Anesthesiology and Pain Medicine, Armed Forces Capital Hospital, Seongnam; ‡ Department of Anesthesiology and Pain Medicine, Seoul National University Bundang Hospital, Seongnam, Korea
†
& Abstract Objective: The positive effects of percutaneous epidural neuroplasty (PEN) likely result from elimination of fibrous tissue. However, a direct link between epidural adhesions and pain symptoms is debatable. We tested the hypothesis that epidurographic improvements correspond to improved patient outcome. Methods: In this prospective study, patients with a filling defect on initial epidurography underwent PEN. Two weeks later, contrast agent distribution around the target area was assessed with repeat epidurography. A successful treatment was defined as over a 50% reduction in visual analog scale (VAS) score 2 weeks postprocedure. The demographic data, history of lumbar spine operation, target nerve, diagnosis, VAS scores, degree of epidurographic improvement, and patient satisfaction were compared between the successful treatment group (Group I) and unsuccessful treatment group (Group II).
Results: Seventy-nine patients were included. Epidurographic findings improved in 67.1% of patients 2 weeks after the procedure. Following PEN, the mean VAS scores of all patients were significantly decreased at 2 weeks (4.12 2.34), 1 month (3.56 2.30), 3 months (3.84 2.45), and 6 months (4.13 2.71) compared with the initial scores (7.82 1.78). In the comparison between Groups I and II, the rate of epidurographic improvement in Group I was higher than in Group II (P = 0.022). Satisfaction in patients that had epidurographic improvement (median satisfaction: 4) was higher than in patients that did not have epidurographic improvement (median satisfaction: 3; P = 0.003). Conclusion: The epidurographic changes following PEN correlate with patient-assessed pain relief and satisfaction. & Key Words: epidurography, epidural injections, epidural neuroplasty, low back pain, treatment outcome
INTRODUCTION Address correspondence reprint requests to: Pyung Bok Lee, MD, PhD, Department of Anesthesiology and Pain Medicine, Seoul National University Bundang Hospital, 166, Gumi-ro, Bundang-gu, Seongnam 463-707, Korea. E-mail: [email protected]. Submitted: October 15, 2013; Revised: December 26, 2013; Revision accepted: January 27, 2014 DOI. 10.1111/papr.12197
© 2014 World Institute of Pain, 1530-7085/14/$15.00 Pain Practice, Volume 15, Issue 5, 2015 407–413
Low back pain and/or lower extremity pain is a common problem that is sometimes difficult to treat. In chronic refractory low back pain and/or radicular pain, interventional pain management by percutaneous epidural neuroplasty (PEN) is a favorable treatment method.1 The effects of percutaneous epidural neuroplasty are believed to result from adhesiolysis or decompression of the involved nerve root, which leads to improved
408
KIM ET AL.
targeting of drug delivery and subsequent therapeutic effects.2–5 However, whether or not epidural adhesion is the cause of pain is still under debate.6–12 Epidural fibrosis can occur not only after spinal surgery, but also as a result of infection, hematoma, annular tears, intrathecal contrast media, or herniated intervertebral disks.13,14 The resulting adhesions may cause mechanical compression or chemical reaction in the nerve, which are associated with low back pain and/or radicular pain. This study investigates the use of epidurography in the assessment of epidural adhesions pre- and postneuroplasty and evaluates the relationship between postPEN epidurographic change and patient outcome. If an epidurographic filling defect correlates with the symptoms, it is meaningful for the clinical diagnosis. It is thought that if the improvement in epidural adhesion after epidural neuroplasty is associated with an improvement in patient symptoms, the adhesion plays a role in the pain. We tested the hypothesis that epidurographic improvement following PEN is related to patient outcome.
METHODS After obtaining the approval of our institutional review board (IRB No. B-1007/106-106), we performed a prospective study in our hospital from June 2007 to December 2010. Patients that had been diagnosed with spinal stenosis or herniated intervertebral disk by L-spine MRI and that experienced transient (< 2 weeks) or no relief from epidural block, pharmacotherapy, and exercise underwent epidurography. They were included in the study if epidurography showed a filling defect corresponding to the symptom level and the abnormality on L-spine MRI, and they subsequently underwent PEN. The data of patient’s age, height, weight, sex, history of lumbar spine operation, side of major symptom (left or right), target nerve, diagnosis, visual analog scale (VAS) scores, improvement in epidurographic filling defect, and patient satisfaction were collected. To determine the effect of treatment, the 10-cm VAS score—0 being no pain and 10 being the most severe pain—was administered prior to the PEN, and at 2 weeks, 1 month, 3 months, and 6 months postneuroplasty. The satisfaction was rated using a 5-point Likert scale: 1 = very unsatisfactory, 2 = unsatisfactory, 3 = neutral, 4 = satisfactory, and 5 = very satisfactory. For epidurography, the tip of an epidural needle was positioned at the level of the center of the S3 foramen, and 20 mL of
contrast media (OMNIPAQUETM; GE Healthcare, Waukesha, Wl, USA) was injected under fluoroscopic guidance.15–17 PEN was performed using the Racz catheter. Exclusion criteria were age under 20 years, lack of informed consent, coagulopathy, pregnancy, active infection at the injection site, or allergic reaction to injected materials for epidural neuroplasty. An RK needle was inserted into the epidural space through the sacral hiatus under fluoroscopic guidance. Then, the Racz catheter was introduced and its tip positioned close to the filling defect, that is, at the level of the symptomatic nerve. After 2 mL of contrast media was administered under continuous fluoroscopic guidance, its distribution in the epidural space and absence of spread to the intravascular, subdural, or intrathecal spaces were confirmed. Hyaluronidase (1,500 units; H-laseâ, Kuhnil Pham, Korea) was administered through the indwelling catheter. The patient was subsequently taken out of the theater and returned to the ward, and 8 mL of 1% mepivacaine was injected via the catheter in split doses of 0.5 to 1 mL at 5-minute intervals. After 20 minute, if no motor weakness or other complications were evident, 8 mL of 10% hypertonic saline was injected in the same manner. On the second day, 8 mL of 1% mepivacaine mixed with 40 mg of triamcinolone and 8 mL of 10% hypertonic saline were injected through the indwelling catheter. On the third day, the protocol was completed with injection of 8 mL of 1% mepivacaine and the catheter was removed (Figure 1). After 2 weeks, a second epidurography was conducted to assess any change in epidural filling defects. Epidurograms of each patient (pre- and postprocedure anteroposterior [AP] views) were analyzed by a radiologist and an experienced pain clinician, who were not involved the procedures and were only aware of the spinal level to be investigated. The analysis of epidurograms was categorized as “improvement” or “no improvement.” Epidurographic improvement at the symptomatic level was defined as postprocedure contrast extending farther than preprocedure contrast in anteroposterior views (Figure 2). When the analyses differed, a second radiologist assessed the epidurograms and a consensus was reached. A successful treatment after 2 weeks was defined as over a 50% reduction in VAS score postprocedure. These cases comprised Group I. The cases with a reduction of < 50% in VAS score postprocedure comprised Group II. The demographic data, history of lumbar spine operation, side of major symptom, target nerve, diagnosis, degree of epidurographic improvement, and patient
Epidurographic Improvement in Epidural Neuroplasty 409
Figure 1. Schematic protocol of the study. HIVD, herniated intervertebral disk.
satisfaction were compared between Group I and Group II. The mean differences were analyzed using Student’s t-test or analysis of variance (ANOVA). The proportional differences were evaluated using a chi-square test. P values < 0.05 were considered statistically significant.
RESULTS In total, 79 patients were enrolled in this study. The demographic data are presented in Table 1. Following PEN, 53 patients (67.1%) displayed epidurographic improvement in the filling defect 2 weeks after the procedure. Following PEN, the mean VAS scores of all patients significantly decreased at 2 weeks (4.12 2.34),
1 month (3.56 2.30), 3 months (3.84 2.45), and 6 months (4.13 2.71) compared with the initial scores (7.82 1.78; Figure 3). Two weeks after PEN, Group I comprised 45 patients and Group II comprised 34 patients. There were no significant differences in the demographic data (sex [P = 0.972], age [P = 0.733], height [P = 0.457], and weight [P = 0.945]), pain side (right or left; P = 0.538), associated nerve (L4, 5 or S1; P = 0.941), diagnosis (P = 0.836), history of lumbar spine operation (P = 0.509), or initial VAS scores (7.88 1.74, 7.77 1.85; P = 0.803) between the 2 groups (Table 2). However, the rate of epidurographic improvement in Group I was higher than that in Group II (P = 0.022, 95% confidence interval: 0.121 to 0.851).
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A
B
Figure 2. Initial epidurography (A) and second epidurography (B) 1 week after percutaneous epidural neuroplasty (PEN). This patient had a spine surgery history and displayed left S1 root symptoms and left S1 and S2 area filling defects on the epidurogram (A). Following the procedure, the contrast material distributed to the left side of S1 (B).
Table 1. Demographic Data No. of Patients Sex (M/F) Age (years) Height (cm) Weight (kg) Side of major symptom (Right/Left) Nerve of major symptom L4 L5 S1 Diagnosis Spinal stenosis Herniated intervertebral disk
Table 2. Demographic Data in the Groups I and II 79 37/42 64.5 11.6 161.0 9.4 62.9 8.9 41/38 5 71 3 69 10
M, male; F, female.
No. of patients Sex (M/F) Age (yrs) Height Weight (kg) Side of major symptoms (Right/Left) Nerve of major symptoms L4 L5 S1 Diagnosis Spinal stenosis Herniated intervertebral disk History of lumbar spine operation No. of epidurographic improvement* Median satisfaction*
Group I
Group II
45 (57%) 24/21 64.2 12.0 160.4 9.3 62.8 8.9 22/23
34 (43%) 18/16 65.14 13.95 162.0 9.5 63.0 9.0 19/15
2 39 4
1 30 3
39 6
30 4
14 (31%)
13 (38%)
35 (78%)
18 (53%)
4
3
M, male; F, female; Group I, the patients who had over a 50% reduction in VAS score pre- to postprocedure after 2 weeks; Group II, the patients who had under a 50% reduction in VAS score pre- to postprocedure after 2 weeks. Values are the mean SD. Satisfaction scale: 1 = very unsatisfactory, 2 = unsatisfactory, 3 = neutral, 4 = satisfactory, 5 = very satisfactory. *P < 0.05.
tion: 4) was higher than in patients who did not show epidurographic improvement (median satisfaction: 3; P = 0.003).
DISCUSSION Figure 3. VAS changes for 6 months. *P < 0.05, between initial VAS and each period. VAS, visual analog scale.
Satisfaction in Group I (median satisfaction: 4) was also higher than that in Group II (median satisfaction: 3; P = 0.001; Table 2). Satisfaction in patients who showed epidurographic improvement (median satisfac-
In this study, 67.1% of patients had epidurographic improvement at the PEN treatment level. This study demonstrates that improvements seen on epidurography correspond with improvements in pain score and patient satisfaction. Therefore, PEN may remove some epidural adhesions, and this may be an important factor in successful treatment.
Epidurographic Improvement in Epidural Neuroplasty 411
Percutaneous epidural neuroplasty operates on the premise that epidural adhesions are the cause of symptoms in patients with low back and/or lower extremity pain. Several reports have investigated the relationship between epidural adhesions and pain. Some of these studies confirm that patients displaying scars or adhesions suffer more from severe pain.6,18–22 Other studies have questioned whether epidural adhesions are the cause of pain,9,10,23,24 and some surgeons insist that PEN cannot remove the adhesions. However, as seen in our results, most studies have shown that PEN is an effective treatment of low back pain and/or radicular pain.4,25–29 Rydell et al. described the grade of fibrosis/ adhesion (grade 0 = no significant adhesions, grade 1 = the adhesions formed were thin, sparse, and easily broken, grade 2 = the adhesions were more dense, but could be disrupted with dissection, grade 3 = the adhesions were so dense that they had to be cut with a knife).30 In that description, grade 3 adhesions may be too thick to improve with PEN. Grade 1 or 2 adhesions may respond to PEN. Further investigations of the relationship between grade of fibrosis/adhesion and PEN effectiveness are needed. Although MRI can identify some epidural fibrosis,10,23 surgery and epiduroscopy often show fibrosis that MRI underestimates or misses entirely.18,31,32 In our experience, epidurography can depict a filling defect associated with epidural adhesion in patients with negative MRI findings. Therefore, epidurography shows potential as a sensitive method for detecting epidural adhesions.33 In addition, epidurography is less expensive than MRI and can be readily performed by pain physicians. In 1 study related to epidurographic improvement and pain score,15 14 of 30 (46.7%) patients displayed an epidurographic improvement in contrast spread at the end of the third day after PEN, but this improvement was not related to improved pain behavior. The neuroplasty technique used in this study differed from our study, as the catheter tip was not placed at the symptomatic filling defect area. Therefore, the epidurographic improvement may not have been directly related to the symptomatic improvement, and the lack of correlation between the epidurogram and pain score may not have represented a true effect. In our study of 79 patients, improvements in epidural adhesion following PEN using the Racz catheter were seen in 53 (67.1%) of the 79 patients at 2 weeks following the procedure. We placed the catheter tip at the symptomatic epidural filling defect, and confirmation of epidu-
rographic improvement was limited to the area around the symptomatic nerve area. As epidurographic improvement was related to patients’ outcome, it seems likely that adhesions can cause symptoms that are relieved by neuroplasty. Adhesion formation occurs as a result of epidural perineural fibrosis in which collagen fibers surround the nerve tissue causing lateral spinal stenosis, interrupting arterial perfusion and venous return.34 Although perineural fibrosis is not intrinsically painful, it can lead to mechanical tethering of the dura mater and nerve roots, and interference with nutritional delivery via cerebrospinal fluid. These changes sensitize the nerve root to pressure, which can eventually lead to chronic low back pain.6,13,35 There are some limitations in this study, as only the relationship between the improvement in symptoms and the epidurographic assessment of adhesions after 2 weeks was investigated. A longer follow-up period would provide additional information. In this study, the epidurograms were evaluated by considering the presence or absence of improvement. No validated grading system has been established for the epidurographic assessment of epidural adhesions. If the improvement could be graded, it may be more useful in the prediction of treatment effect and prognosis. A control group receiving mepivacaine and triamcinolone alone and groups with discordant pain levels and epidurographic findings were not included. In conclusion, this study shows that PEN is a promising method for patients who have epidurographic filling defects associated with refractory symptoms, and successful PEN is associated with epidurographic improvement. Although not all epidural adhesions may cause pain, adhesions related to the symptoms can represent a treatment target for PEN.
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