Spinal somatosensory evoked potential to evaluate neurophysiologic changes associated with postlaminotomy fibrosis: an experimental study

Using cross-linked hyaluronic acid gel to prevent postoperative lumbar epidural space adhesion: in vitro and in vivo studies

PURPOSE

Hyaluronic acid prevents tissue adhesion after different surgeries. Physical barriers and inflammatory regulation have been suggested to be involved in the mechanism of these clinical effects. However, the molecular mechanism by which hyaluronic acid prevents epidural adhesion has not yet been reported.

METHODS

In the current in vivo studies, we investigated cross-linked hyaluronic acid gel in the regulation of scar gene expression, the accumulation of fibroblasts in scar tissue, and the prevention of epidural adhesion. The effect of cross-linked hyaluronic acid gel on the secretion of inflammatory factors was observed in vitro. In addition, to ensure the accuracy and reliability of the in vivo gene expression results, we used a cell model to detect the target genes in vitro.

RESULTS

The expression levels of TGFβ1 and COL1A1 mRNA were decreased in the cross-linked hyaluronic acid gel-treated group, and the protein expression of levels TGFβ1 and COL1A1 were also reduced, as detected by Western blotting in vitro and in vivo (P < 0.05). Histomorphometry results demonstrated that the number of fibroblasts in the experimental group was significantly lower than that in the control group 2 weeks postoperatively. Micro-CT scans showed that the cross-linked hyaluronic acid gel could reduce adhesion in the epidural space after laminectomy. Additionally, the cross-linked hyaluronic acid gel could inhibit IL-6 secretion.

CONCLUSIONS

These results indicate that cross-linked hyaluronic acid gel can prevent epidural adhesion by inhibiting inflammatory factors, such as IL-6, and downregulating TGFβ1 and COL1A1 mRNA expression. These slides can be retrieved under Electronic Supplementary Material.

Controllable Risk Factors for Neurologic Complications in Posterior Lumbar Interbody Fusion as Revision Surgery

BACKGROUND

The main concern with revision lumbar surgery is the possibility of neurologic complications. This retrospective study was conducted to clarify the risk factors, especially the effects of nerve stretching, for postoperative neurologic complications in posterior lumbar interbody fusion (PLIF) without excessive nerve retraction by bilateral total facetectomy as revision surgery.

METHODS

Between 2005 and 2015, 50 consecutive patients underwent revision PLIF for recurrent stenosis or recurrent disc herniation. The patients were divided into two groups: patients with neurological complications (NC group) and patients without neurological complications (non-NC group). Radiological examinations to evaluate the magnitude of nerve stretching included the following pre- and postoperative plain radiograph measurements: anterolisthesis at flexion, intervertebral lordosis in the neutral position, and posterior disc height in the neutral position.

RESULTS

Sixteen patients (32%) had neurological complications. The decrease in intervertebral lordosis was significantly greater in the NC group than that in the non-NC group (0.8° vs. -1.5°, P<0.05). Distraction of the posterior disc height was significantly greater in the NC group than that in the non-NC group (5.0 mm vs. 2.6 mm, P < 0.01). Neurological complications were seen in all patients with a decrease in intervertebral lordosis >3° and distraction of the posterior disc height >3 mm.

CONCLUSIONS

Decreased intervertebral lordosis, and distraction of the posterior disc height, which can be controlled by surgeons, appear to be risk factors for neurological complications following revision PLIF. In revision PLIF, surgeons should create segmental lordosis without excessive disc height distraction.

The effect of molecular weight and concentration of hyaluronan on the recovery of the rat sciatic nerve sustaining acute traumatic injury

Acute traumatic peripheral nerve injury remains a significant clinical issue affecting mostly young individuals and their productivity in spite of advances in current medicine. Hyaluronan has been explored in this scenario for its anti-adhesive and high biocompatibility properties for decades. The molecular weight and concentration of the locally applied hyaluronan has been overlooked and not optimized. We used different molecular weights and concentrations of hyaluronan in a rat sciatic nerve crush injury model and found better overall outcomes with high molecular weight (3000 kDa) hyaluronan. The anti-inflammatory effect of the higher molecular weight hyaluronan may have a more favorable effect. We conclude that the optimization of hyaluronan is necessary when incorporating hyaluronan in the engineering of biomaterials for use in acute traumatic peripheral nerve injury.

MMC controlled-release membranes attenuate epidural scar formation in rat models after laminectomy

Epidural scar formation after laminectomy impede surgical outcomes of decompression. Mitomycin C (MMC) has been demonstrated to have significant inhibitory effects on epidural scar. This study was undertaken to develop an effective MMC controlled-release membrane and to investigate its effects on epidural scar in rat models of laminectomy. A total of 72 rats that underwent laminectomy were divided into three groups. Among them, 24 were treated with mitomycin C-polylactic acid (MMC-PLA) controlled-release membrane, 24 with mitomycin C-polyethylene glycol (MMC-PEG) controlled-release membrane, and no treatment was performed for the remaining 24 rats (control group). In the following 4 weeks, magnetic resonance image (MRI), macroscopic observation, histology and hydroxyproline (Hyp) concentration analysis were performed to explore the effects of these three therapies on epidural scar. MRI revealed a significant reduction of epidural fibrosis in MMC-PLA and MMC-PEG treatment groups, compared with the control group. Histological results also showed that collagen deposition was significantly reduced after being treated with MMC-PLA or MMC-PEG membranes. Likewise, Hyp concentrations of the epidural scar tissue in MMC-PLA and MMC-PEG groups were markedly lower than those in the control group. However, regarding the effects on reducing epidural scar, no significant difference was found between the MMC-PLA and MMC-PEG groups. In conclusion, MMC-PLA and MMC-PEG membranes are safe and effective in reducing fibrosis. Thus, MMC-controlled-release membranes promises to be a potential therapeutic in preventing epidural scar formation after laminectomy.

Reduction of Leg Pain by Oxiplex Gel After Lumbar Discectomy in Patients With Predominant Leg Pain and Elevated Levels of Lower Back Pain: A Prospective, Randomized, Blinded, Multicenter Clinical Study

STUDY DESIGN

A prospective, randomized, blinded, multicenter clinical study.

OBJECTIVE

To evaluate carboxymethylcellulose/polyethylene oxide gel (Oxiplex) in improving clinical outcomes in subjects having predominant leg pain and elevated low back pain undergoing first-time lumbar discectomy for disk herniation.

SUMMARY OF BACKGROUND DATA

Clinical studies in the United States and Italy found that Oxiplex reduced leg pain after decompression surgery.

METHODS

A total of 68 subjects with herniated lumbar disk were enrolled and randomized into treatment (surgery plus gel) or surgery-only control groups. A prospective statistical analysis assessed the effect of gel in the severe back pain subgroup (prespecified as greater than or equal to median baseline back pain of the population studied). All subjects except 2 controls lost to follow-up completed the study. Preoperative and postoperative visual analogue scale leg pain scores were analyzed and compared between groups at 60 days after surgery.

RESULTS

There were no serious adverse events or neurological safety concerns reported in any patients. Gel-treated patients had statistically significantly lower visual analogue scale leg pain scores at study end compared with controls (P=0.0240), representing a 21% additional reduction in leg pain compared with surgery alone in the severe baseline back pain subgroup (P=0.0240). The proportion of subgroup patients experiencing zero leg pain at study end was significantly higher in the gel treatment group (60%) than in the control group (23%) (P=0.0411).

CONCLUSIONS

The data from this study confirm and extend results of 2 previous studies in Italy and the United States that reported statistically significantly greater reductions in leg pain in gel-treated patients with severe preoperative low back pain compared with patients who only underwent decompression surgery.

CCN2 and CCN5 exerts opposing effect on fibroblast proliferation and transdifferentiation induced by TGF-β

Epidural fibrosis might occur after lumbar discectomy and contributes to failed back syndrome. Transforming growth factor (TGF)-β has been reported to influence multiple organ fibrosis, in which connective tissue growth factor/cysteine-rich 61/nephroblastoma overexpressed 2 (CCN2) and CCN5 are involved. However, the effect of CCN2 and CCN5 on TGF-β induced fibrosis has not yet been elucidated. This study reports that CCN2 and CCN5 play opposing roles in cell proliferation and transdifferentiation of human skin fibroblasts or rabbit epidural scar-derived fibroblasts exposed to TGF-β. We observed that TGF-β1 induced fibroblasts proliferation and differentiation in a dose-dependent manner (from 0 μg/L to 20 μg/L). Meanwhile, CCN2 expression is up-regulated while CCN5 expression is inhibited by TGF-β1 exposure. Furthermore, it is demonstrated that CCN2 overexpression leads to promoted proliferation and elevated collagen and α-smooth muscle actin (α-SMA) expression, which are inhibited by CCN5 overexpression. Moreover, it is shown that the cysteine knot (CT) domain, present in CCN2 but absent in CCN5, plays an essential part in fibroblast proliferation and differentiation. Additionally, enhanced TGF-β and CCN2 expression but decreased CCN5 expression is found in rabbit epidural scar-derived fibroblasts. Overall, the results show the opposing effects of CCN2 and CCN5 on fibroblast proliferation and transdifferentiation induced by TGF-β.

Efficacy of Percutaneous Adhesiolysis in the Treatment of Lumbar Post Surgery Syndrome

Context

Lumbar post-surgery syndrome is common and often results in chronic, persistent pain and disability, which can lead to multiple interventions. After failure of conservative treatment, either surgical treatment or a nonsurgical modality of treatment such as epidural injections, percutaneous adhesiolysis is often contemplated in managing lumbar post surgery syndrome. Recent guidelines and systematic reviews have reached different conclusions about the level of evidence for the efficacy of epidural injections and percutaneous adhesiolysis in managing lumbar post surgery syndrome. The objective of this systematic review was to determine the efficacy of all 3 percutaneous adhesiolysis anatomical approaches (caudal, interlaminar, and transforaminal) in treating lumbar post-surgery syndrome.

Evidence Acquisition

Data Sources: A literature search was performed from 1966 through October 2014 utilizing multiple databases. Study Selection: A systematic review of randomized trials published from 1966 through October 2014 of all types of epidural injections and percutaneous adhesiolysis in managing lumbar post-surgery syndrome was performed including methodological quality assessment utilizing Cochrane review criteria, Interventional Pain Management Techniques–Quality Appraisal of Reliability and Risk of Bias Assessment (IPM–QRB), and grading of evidence using 5 levels of evidence ranging from Level I to Level V. Data Extraction: The search strategy emphasized post-surgery syndrome and related pathologies treated with percutaneous adhesiolysis procedures.

Results

The search criteria yielded 16 manuscripts on percutaneous adhesiolysis assessing post-surgery syndrome. Of these, only 4 randomized trials met inclusion criteria for methodological quality assessment, 3 of them were of high quality; and the fourth manuscript was of low quality. Based on these 3 randomized controlled trials, 2 of them with one-day procedure and one with a 3-day procedure, the level of evidence for the efficacy of percutaneous adhesiolysis is Level II based on best evidence synthesis.

Conclusions

Based on this systematic review, percutaneous adhesiolysis is effective in managing patients with lumbar post-surgery syndrome after the failure of conservative management including fluoroscopically directed epidural injections.

Changes in excursion and strain in the rat sciatic nerve under cauda equina compression induced by epidural balloon inflation

BACKGROUND CONTEXT

Healthy nerves are able to stretch and glide as responses to normal physiological movement. Injury to the nerve may alter the nerve's mechanical properties and result in neuropathy. Whether cauda equina compression alters the mechanical properties of the sciatic nerve is still unclear.

PURPOSE

The purpose of this study was to demonstrate the changes in excursions and strains of the sciatic nerve in vivo after acute cauda equina compression was induced by epidural balloon compression.

STUDY DESIGN

An animal comparative study with induced cauda equina compression was designed for in situ measurements of nerve properties.

METHODS

Twenty-six adult Sprague-Dawley rats were divided into three groups. The balloon group (n=10) underwent epidural compression induced by inflation of an embolectomy balloon catheter that was inserted through an L6 laminotomy. The control group (n=10) underwent laminotomy but without compression. The normal group (n=6) received no back surgery. This model of neuropathy was confirmed with electrophysiological examination. The excursions and strains of the sciatic nerve in response to the modified straight leg-raising (SLR) test were measured in situ and analyzed.

RESULTS

The scales of the excursions were lower in the balloon group than in the other two groups, in both 90° flexion and extension of the knee. The balloon group was more sensitive to positional changes. The strain was significantly higher under the condition of epidural balloon compression.

CONCLUSIONS

We concluded that cauda equina compression decreased the excursion and increased the strain of the sciatic nerve in response to a modified SLR test. These findings might indicate one of the mechanisms of the pain provoked by the SLR test and also possibly contribute to an understanding of the pathogenesis of the neuropathy in the lower limbs of patients with cauda equina compression.

The use of a dehydrated amnion/chorion membrane allograft in patients who subsequently undergo reexploration after posterior lumbar instrumentation

Background Context. Products that can reduce development of epidural fibrosis may reduce risk for ongoing pain associated with development of scar tissue and make subsequent epidural reexploration easier. Purpose. To evaluate the use of dehydrated human amnion/chorion membrane (dHACM) on the formation of soft tissue scarring in the epidural space. Study Design. Case series. Patient Sample. Five patients having transforaminal lumbar interbody lumbar fusion (TLIF) with posterior instrumentation and implantation of dHACM in the epidural space and subsequent epidural reexploration. Outcome Measures. Degree of scar tissue adjacent to the epidural space at reexploration. Intraoperative and postoperative complications related to dHACM and patient reported outcomes. Methods. The degree of scar tissue adjacent to the epidural space was assessed during the reexploration surgery. Patients' outcomes were collected using standard validated questionnaires. Results. Four of 5 cases had easily detachable tissue during epidural reexploration. Angiolipoma of 10% was noted in 1 case and 5% in 2 cases. Significant improvements in patient reported outcomes were observed. No intraoperative or postoperative complications occurred. Conclusions. Our findings suggest that dHACM implant during TLIF may have favorable effects on epidural fibrosis and is well tolerated. Further studies with larger cohorts are required to prove our results.

Potential risk of mitomycin C at high concentrations on peripheral nerve structure

Although the local application of mitomycin C may prevent epidural adhesion after laminectomy, mitomycin C can induce neurotoxicity in optic and acoustic nerves at high concentrations. To determine the safe concentration range for mitomycin C, cotton pads soaked with mitomycin C at different concentrations (0.1, 0.3, 0.5, and 0.7 mg/mL) were immediately applied for 5 minutes to the operation area of rats that had undergone laminectomy at L₁. Rat sciatic nerves, instead of dorsal nerves, were used in this study. The results showed that mitomycin C at 0.1-0.5 mg/mL did not damage the structure and function of the sciatic nerve, while at 0.7 mg/mL, mitomycin C significantly reduced the thickness of the sciatic nerve myelin sheath compared with lower concentrations, though no functional change was found. These experimental findings indicate that the local application of mitomycin C at low concentrations is safe to prevent scar adhesion following laminectomy, but that mitomycin C at high concentrations (> 0.7 mg/mL) has potential safety risks to peripheral nerve structures.

Immunomodulatory effectiveness of licofelone in preventing epidural fibrosis in post-laminectomy rat

OBJECTIVE

The object of this study was to investigate the effects of licofelone on the prevention of epidural fibrosis (EF) formation in post-laminectomy rat models.

METHODS

A controlled double-blinded study was conducted in sixty, healthy adult Wistar rats that underwent laminectomy at the L1-L2 vertebrae levels. All the rats were divided randomly into three groups according to the treatment (via oral gavage): (1) licofelone treatment group; (2) vehicle treatment group; (3) sham group (laminectomy without treatment). All rats were euthanized humanely 4 weeks postoperatively. The macroscopic assessment of EF, hydroxyproline content in epidural scar tissue, histological analysis, and the mRNA measurements of interleukin-6 (IL-6) and transforming growth factor-β1 were performed.

RESULTS

The Rydell score, hydroxyproline content, epidural scar density, and inflammatory factors expressions all suggested better results in licofelone group than the other two groups.

CONCLUSION

The application of licofelone could reduce hydroxyproline deposits, inflammatory factors expressions and prevent epidural adhesions in post-laminectomy rats.

Significance of the mass-compression effect of postlaminectomy/laminotomy fibrosis on histological changes on the dura mater and nerve root of the cauda equina: an experimental study in rats

PURPOSE

The precise mechanism and pathological role of postlaminectomy/laminotomy fibrosis (PLF) in postoperative neurological deficits have not been established. Many studies use magnetic resonance imaging (MRI) to prove that there is no consistent correlation between PLF and postoperative neurological deficits and back pain (PNDBP). Therefore, we assumed that the direct-compression effect may not be the only factor but that other neurological deficits associated with pathological mechanisms should exist and need more investigation. The purpose of this study was to compare over time the differences and changes in histopathological properties of PLF in rats.

METHODS

We used a rat model with walking-track analysis for neurologic evaluation, grading scale to evaluate PLF, histomorphometric measurements of dura sac diameter, and histological tissue reactions (dura mater and spinal rootlets) juxtaposed to the postlaminectomy/laminotomy defect. The 54 adult Sprague-Dawley rats were divided into laminotomy (n = 18), laminectomy (n = 18), and sham-operation groups (n = 18). All groups were subdivided into three equal subgroups based on different postoperative time points (1, 2, and 3 months). All sections of vertebral column were stained with hematoxylin and eosin and with Masson's trichrome.

RESULTS

The results showed that only a slight compression effect reflected by nonsignificant changes in the maximum anterior-posterior diameters within the dura sac, in the walking tract test, and increased grades of PLF over time. In addition, significant pathological inflammatory changes, such as thickening of the dura mater, axonal swelling, and neovascularization, were found in the post-laminectomy/laminotomy groups at each time point.

CONCLUSION

Laminectomy-/laminotomy-related inflammation may lead to PLF, and these pathological changes may be the main cause of postoperative neurological deficits. These findings show that research on preventing PLF should include perioperative modulation of inflammatory reactions induced by laminectomy/laminotomy.

Reduction of epidural fibrosis and dural adhesions after lamina reconstruction by absorbable cement: an experimental study

BACKGROUND CONTEXT

Post-laminectomy epidural fibrosis complicates revision spine surgery and is implicated in cases of "failed back syndrome." Several materials have been used to minimize epidural fibrosis with varying results.

PURPOSE

The aim of this study was to examine the impact of reconstruction of laminectomy site with a type of absorbable cement (Jectos) to reduce epidural fibrosis.

STUDY DESIGN

This investigation is an experimental controlled study, which is designed to evaluate the preventive effects of laminectomy site reconstruction in rat laminectomy model.

METHODS

Twenty wistar rats were included in this study and divided randomly to two equal groups, namely, subject and control. In both groups, laminectomy was performed in L2 and L4 levels. Control group received no additional treatment. In the subject group, L4 levels were reconstructed by Jectos and L2 levels were non-reconstructed as internal controls. Six months after surgery the rats were sacrificed and the dural adhesion and epidural fibrosis were evaluated macroscopically and microscopically. The study was financially supported by Brain and Spinal Cord Injuries Repair Center. None of the authors have any conflict of interest.

RESULTS

Non-reconstructed levels in both groups showed dense epidural fibrosis with marked dural adherence. L4 reconstructed levels in subject group showed reduced epidural fibrosis macroscopically (p=.024) and microscopically (p=.041). No foreign body reaction or ossification occurred at reconstructed sites.

CONCLUSIONS

In the present study, lamina reconstruction with absorbable cement was a safe method that significantly reduced post-laminectomy epidural fibrosis and dural adhesions in rat laminectomy model.

Endoplasmic reticulum stress signaling is involved in mitomycin C (MMC)-induced apoptosis in human fibroblasts via PERK pathway

Endoplasmic reticulum (ER) stress-mediated cell apoptosis has been implicated in various cell types, including fibroblasts. Previous studies have shown that mitomycin C (MMC)-induced apoptosis occurs in fibroblasts, but the effects of MMC on ER stress-mediated apoptosis in fibroblasts have not been examined. Here, MMC-induced apoptosis in human primary fibroblasts was investigated by exposing cells to a single dose of MMC for 5 minutes. Significant inhibition of cell proliferation and increased apoptosis were observed using a cell viability assay, Annexin V/propidium iodide double staining, cell cycle analysis, and TUNEL (terminal deoxynucleotidyl transferase dUTP nick-end labeling) staining. Upregulation of proapoptotic factors, including cleaved caspase-3 and poly ADP-ribose polymerase (PARP), was detected by Western blotting. MMC-induced apoptosis was correlated with elevation of 78-kDa glucose-regulated protein (GRP78) and C/EBP homologous protein (CHOP), which are hallmarks of ER stress. Three unfolded protein response (UPR) sensors (inositol-requiring enzyme 1, IRE1; activating transcription factor 6, ATF6; and PKR-like ER kinase, PERK) and their downstream signaling pathways were also activated. Knockdown of CHOP attenuated MMC-induced apoptosis by increasing the ratio of BCL-2/BAX and decreasing BIM expression, suggesting that ER stress is involved in MMC-induced fibroblast apoptosis. Interestingly, knockdown of PERK significantly decreased ER stress-mediated apoptosis by reducing the expression of CHOP, BIM and cleaved caspase-3. Reactive oxygen species (ROS) scavenging also decreased the expression of GRP78, phospho-PERK, CHOP, and BIM. These results demonstrate that MMC-induced apoptosis is triggered by ROS generation and PERK activation.

Inhibition of epidural fibrosis after microendoscopic discectomy with topical application of mitomycin C: a randomized, controlled, double-blind trial

OBJECT

The authors conducted a study to evaluate the effects and the safety of locally applied mitomycin C (MMC) on epidural fibrosis after microendoscopic discectomy (MED).

METHODS

Seventy-five patients undergoing single-level unilateral MED for lumbar disc herniation were randomly assigned to receive cotton wool impregnated with either 0.5 mg/ml MMC or saline applied at the site of discectomy for 5 minutes. Outcome measures included degrees of pain severity, functional disability, physical symptoms, and quantitative evaluation of postoperative epidural fibrosis shown on follow-up lumbar contrast-enhanced MRI.

RESULTS

Sixty-two patients completed the follow-up. Neither serious drug adverse effects nor clinically significant laboratory adverse effects were observed. Patients in both groups showed similar clinical recoveries postoperatively. A statistically significant difference (p < 0.05) between the 2 treatments was shown in a quantitative evaluation of postoperative MRI-documented epidural fibrosis in the MMC group and the saline group using a modified grading system. The mean cross-sectional areas of epidural fibrosis were 7.32-70.06 mm(2) in the MMC group and 22.94-90.48 mm(2) in the saline group. The epidural fibrosis index ranged from 0.0296 to 0.3267 in the MMC group and from 0.1191 to 0.3483 in the saline group. A significant difference was also observed using the Ross grading system to evaluate postoperative MR images.

CONCLUSIONS

Although no benefit was observed clinically, the authors observed a notable reduction of epidural fibrosis after MED radiologically, with 0.5 mg/ml MMC locally applied and no clinical side effects.

Assessment of effectiveness of percutaneous adhesiolysis and caudal epidural injections in managing post lumbar surgery syndrome: 2-year follow-up of a randomized, controlled trial

Background

The literature is replete with evaluations of failed surgery, illustrating a 9.5%–25% reoperation rate. Speculated causes of post lumbar surgery syndrome include epidural fibrosis, acquired stenosis, recurrent disc herniation, sacroiliac joint pain, and facet joint pain among other causes.

Methods

Patients (n = 120) were randomly assigned to two groups with a 2-year follow-up. Group I (control group, n = 60) received caudal epidural injections with catheterization up to S3 with local anesthetic (lidocaine 2%, 5 mL), nonparticulate betamethasone (6 mg, 1 mL), and 6 mL of 0.9% sodium chloride solution. Group II (intervention group, n = 60) received percutaneous adhesiolysis of the targeted area, with targeted delivery of lidocaine 2% (5 mL), 10% hypertonic sodium chloride solution (6 mL), and nonparticulate betamethasone (6 mg). The multiple outcome measures included the Numeric Rating Scale, the Oswestry Disability Index 2.0, employment status, and opioid intake with assessments at 3, 6, 12, 18, and 24 months posttreatment. Primary outcome was defined as 50% improvement in pain and Oswestry Disability Index scores.

Results

Significant improvement with at least 50% relief with pain and improvement in functional status was illustrated in 82% of patients at the 2-year follow-up in the intervention group compared to 5% in the control group receiving caudal epidural injections. The average number of procedures over a period of 2 years in Group II was 6.4 ± 2.35 with overall total relief of approximately 78 weeks out of 104 weeks.

Conclusion

The results of this study show significant improvement in 82% of patients over a period of 2 years with an average of six to seven procedures of 1-day percutaneous adhesiolysis in patients with failed back surgery syndrome.

Oxiplex reduces leg pain, back pain, and associated symptoms after lumbar discectomy

STUDY DESIGN

Prospective, randomized, blinded clinical trial.

OBJECTIVE

To evaluate effectiveness of Oxiplex gel for reduction of pain and associated symptoms after lumbar discectomy.

SUMMARY OF BACKGROUND DATA

Oxiplex gel (carboxymethylcellulose, polyethylene oxide, and calcium) is used during discectomy to coat the surgical site for reduction of pain and symptoms after lumbar discectomy.

METHODS

Patients undergoing single-level lumbar discectomy performed by laminectomy or laminotomy and randomized to receive either surgery plus Oxiplex gel (treatment group) or surgery alone (control group) were assessed 6 months after surgery using (1) a quality of life questionnaire (Lumbar Spine Outcomes Questionnaire [LSOQ]) and (2) clinical evaluations.

RESULTS

There were no statistically significant differences in baseline demographics, surgical procedures, LSOQ scores, and clinical evaluations between treatment (N = 177) and control (N = 175) groups. More gel-treated patients were satisfied with outcome of their surgical treatment than control patients (P = 0.05). The gel-treated group showed greater reductions in pain and symptoms from baseline compared with surgery-only controls. Additional benefits of gel were consistently shown in reduction of leg and back pain at 6 months in the patient population having substantial back pain at baseline (greater than or equal to the median LSOQ pain score of 63). In that population, there was a statistically significant reduction of leg pain and back pain (P < 0.01) in the treatment group compared with controls. Fewer patients in the treatment group had abnormal musculoskeletal physical examinations at 6 months compared with controls. There were no cases of cerebrospinal fluid leaks and no differences in laboratory values or vital signs. Patients in the treatment group had less hypoesthesia, paraesthesia, sensory loss, and fewer reoperations during the 6-month follow-up than controls (1 vs. 6).

CONCLUSION

These data demonstrate improvements in clinical outcomes resulting from the use of Oxiplex gel in discectomy procedures for treatment of lumbar disc herniation.

Fluoroscopic caudal epidural injections in managing post lumbar surgery syndrome: two-year results of a randomized, double-blind, active-control trial

STUDY DESIGN

A randomized, active control, double-blind trial.

OBJECTIVE

To evaluate the effectiveness of fluoroscopically directed caudal epidural injections with or without steroids in managing chronic low back and lower extremity pain secondary to post lumbar surgery syndrome.

SUMMARY OF BACKGROUND DATA

There is a paucity of evidence concerning caudal epidural injections for managing chronic persistent low back pain with or without lower extremity pain caused by post lumbar surgery syndrome.

METHODS

This active control randomized study included 140 patients with 70 patients in each group. Group I received 0.5% lidocaine, 10 mL; Group II received 9 mL of 0.5% lidocaine mixed with 1 mL of 6 mg of nonparticulate betamethasone. The multiple outcome measures included the numeric rating scale, the Oswestry Disability Index 2.0, employment status, and opioid intake with assessments at 3, 6, 12, 18, and 24 months posttreatment. Primary outcome was defined as at least 50% improvement in pain and Oswestry Disability Index scores. Patients with a positive response to the first 2 procedures with at least 3 weeks of relief were considered to be successful. All others were considered as failures.

RESULTS

Overall in Group I, 53% and 47% of the patients and in Group II, 59% and 58% of the patients, showed significant improvement with reduction in pain scores and disability index at 12 months and 24 months. In contrast, in the successful groups, significant pain relief and improvement in function were observed in 70% and 62% of Group I at one and 2 years; in 75% and 69% of Group II at one and 2 years. The results in the successful group showed that at the end of the first year patients experienced approximately 38 weeks of relief and at the end of 2 years Group I had 62 weeks and Group II had 68 weeks of relief. Overall total relief for 2 years was 48 weeks in Group I and 54 weeks in Group II. The average procedures in the successful groups were at 4 in one year and 6 at the end of 2 years.

CONCLUSION

Caudal epidural injections of local anesthetic with or without steroid might be effective in patients with chronic persistent low back and/or lower extremity pain in patients with post lumbar surgery syndrome.

Use of Temporary Implantable Biomaterials to Reduce Leg Pain and Back Pain in Patients with Sciatica and Lumbar Disc Herniation

The principle etiology of leg pain (sciatica) from lumbar disc herniation is mechanical compression of the nerve root. Sciatica is reduced by decompression of the herniated disc, i.e., removing mechanical compression of the nerve root. Decompression surgery typically reduces sciatica more than lumbar back pain (LBP). Decompression surgery reduces mechanical compression of the nerve root. However, decompression surgery does not directly reduce sensitization of the sensory nerves in the epidural space and disc. In addition, sensory nerves in the annulus fibrosus and epidural space are not protected from topical interaction with pain mediators induced by decompression surgery. The secondary etiology of sciatica from lumbar disc herniation is sensitization of the nerve root. Sensitization of the nerve root results from a) mechanical compression, b) exposure to cellular pain mediators, and/or c) exposure to biochemical pain mediators. Although decompression surgery reduces nerve root compression, sensory nerve sensitization often persists. These observations are consistent with continued exposure of tissue in the epidural space, including the nerve root, to increased cellular and biochemical pain mediators following surgery. A potential contributor to lumbar back pain (LBP) is stimulation of sensory nerves in the annulus fibrosus by a) cellular pain mediators and/or b) biochemical pain mediators that accompany annular tears or disruption. Sensory fibers located in the outer one-third of the annulus fibrosus increase in number and depth as a result of disc herniation. The nucleus pulposus is comprised of material that can produce an autoimmune stimulation of the sensory nerves located in the annulus and epidural space leading to LBP. The sensory nerves of the annulus fibrosus and epidural space may be sensitized by topical exposure to cellular and biochemical pain mediators induced by lumbar surgery. Annulotomy or annular rupture allows the nucleus pulposus topical access to sensory nerve fibers, thereby leading to LBP. Coverage of the annulus and adjacent structures in the epidural space by absorbable viscoelastic gels appears to reduce LBP following surgery by protecting sensory fibers from cellular and biochemical pain mediators.

Study on the optimal concentration of topical mitomycin-C in preventing postlaminectomy epidural adhesion

There is increasing evidence that topical application of mitomycin-C can be beneficial in reducing epidural scar adhesion. However, the ideal concentration of mitomycin-C is unknown. The purpose of this study was to verify its efficacy for preventing epidural adhesion and the immediate electrophysiological responses caused by it in a laminectomy model. Seventy rats underwent laminectomy at L-1 and L-2. Cotton pads soaked with saline and various concentrations of mitomycin-C (0.1 mg/ml, 0.3 mg/ml, 0.5 mg/ml and 0.7 mg/ml) were applied to the exposed dura for 5 min. Spine somatosensory evoked potentials (SSEP) were monitored in preoperative and the immediate electrophysiological responses of mitomycin-C used. Four weeks postlaminectomy the rats were killed. The area of epidural scar tissue and degree of epidural adhesion were determined by 7.0 T Micro MR imaging. Macroscopic evaluations were performed according to the Rydell standard. The results showed that severe epidural adhesion was formed in the saline group and no dural adherence or incomplete adhesions were found in the mitomycin-C group. The Rydell classification and the degree of epidural adhesion and the area of the scar in 0.5 mg/ml group and 0.7 mg/ml mitomycin-C group revealed a significant decrease compared with the control group and 0.1 mg/ml group and 0.3 mg/ml mitomycin-C group. The spine sensory evoked potentials did not alter obviously in both preoperative and the immediate electrophysiological responses of mitomycin-C used. In conclusion, locally applied mitomycin-C in a concentration of 0.5 mg/ml and 0.7 mg/ml mitomycin-C may be the optimal concentration in preventing postlaminectomy epidural adhesion.

PATHOANATOMIC BASIS FOR STRETCH-INDUCED LUMBAR NERVE ROOT INJURY WITH A REVIEW OF THE LITERATURE

OBJECTIVE

Persistent pain originating from a dysfunctional lumbar motion segment poses significant challenges in the clinical arena. Although the predominance of the existing spine literature has addressed nerve root compression as the principal cause of pain, it is equally likely that a stretch mechanism may be responsible for all or part of the pathology.

METHODS

The literature supporting the role of stretch damage as a primary cause of nerve root injury and pain was systematically reviewed. Pathoanatomic considerations between nerve roots and juxtaposed environment are described and correlated with the available literature. Potential anatomic relationships that may lead to stretch-induced injury are delineated.

RESULTS

A dynamic lumbar functional spinal unit that encloses a tethered nerve root can create significant stretch and/or compression. This phenomenon may be present in a variety of pathological conditions. These include anterior, posterior, and rotatory olisthesis as well as degenerative conditions such as the loss of disc interspace height and frank multisegment spinal deformity. Although numerous studies have demonstrated that stretch can result in nerve damage, the pathophysiology that may associate nerve stretch with chronic pain has yet to be determined.

CONCLUSION

The current literature concerning stretch-related injury to nerve roots is reviewed, and a conceptual framework for its diagnosis and treatment is proposed and graphically illustrated using cadaveric specimens. The dynamic biomechanical and functional interrelationships between neural structures and adjacent connective tissue elements are particularly important in the face of spinal deformity.

Neurophysiological and histopathological evaluation of low-dose radiation on the cauda equina and postlaminotomy fibrosis: an experimental study in the rat

STUDY DESIGN

We evaluated the electrophysiological changes to the cauda equina after low-dose external irradiation in a postlaminotomy fibrosis model in rats.

OBJECTIVE

To clarify the immediate and long-term electrophysiological responses of antifibrotic radiation therapy in a fibrosis model.

SUMMARY OF BACKGROUND DATA

Low-dose perioperative radiation therapy inhibits scar formation. However, its efficacy for preventing fibrosis-induced compressive neuropathy and its potential adverse effect on underlying neural structures have not been studied.

METHODS

Twenty-four rats were placed in 3 groups of 8: group I, sham operation (laminar exposure alone) with a single fraction of 700 cGy external irradiation given using a 9-MeV electron beam 24 hours postsurgery; group II, left L5 hemilaminectomy (laminotomy) alone; and group III, left L5 hemilaminectomy with the same radiation protocol as group 1. We recorded mixed-nerve-elicited somatosensory-evoked potentials (M-SSEP)- and dermal (D)-SSEP at the thoracolumbar junction, and L1-L2 interspinous ligament after percutaneously stimulating the posterior tibial nerve at the bilateral medial ankle and L5 dermatomal fields. We compared the potentials recorded immediately before, 30 minutes, 2 weeks, and 1, 2, and 3 months after surgery on the operated and nonoperated sides. We used gross dissection and histologic sections to evaluate the degree of perineural fibrosis and walking-track analysis for neurologic evaluation.

RESULTS

Pre- and postoperative (30 minutes and 2 weeks) M- and D-SSEP were not statistically different. In group II, the relative amplitude of D-SSEP (elicited from 5 dermatomes) 1, 2, and 3 months postsurgery was lower; however, the M-SSEP in all groups and D-SSEP of groups I and III remained constant. Histologic evaluation of radiation efficacy showed that the frequency and extent of peridural fibrosis was consistently lower in group II than in group III.

CONCLUSION

Low-dose irradiation reduced peridural fibrosis and prevented fibrosis-induced radiculopathy. The radiation caused no adverse neuropathic complications.