Mitomycin C in preventing spinal epidural fibrosis in a laminectomy model in rats

Multi-functional dual-layer nanofibrous membrane for prevention of postoperative pancreatic leakage

Postoperative pancreatic leakage due to pancreatitis in patients is a life-threatening surgical complication. The majority of commercial barriers are unable to meet the demands for pancreatic leakage due to poor adhesiveness, toxicity, and inability to degrade. In this study, we fabricated mitomycin-c and thrombin-loaded multifunctional dual-layer nanofibrous membrane with a combination of alginate, PCL, and gelatin to resolve the leakage due to suture line disruption, promote hemostasis, wound healing, and prevent postoperative tissue adhesion. Electrospinning was used to fabricate the dual-layer system. The study results demonstrated that high gelatin and alginate content in the inner layer decreased the fiber diameter and water contact angle, and crosslinking allowed the membrane to be more hydrophilic, making it highly biodegradable, and adhering firmly to the tissue surfaces. The results of in vitro biocompatibility and hemostatic assay revealed that the dual-layer had a higher cell proliferation and showed effective hemostatic properties. Moreover, the in vivo studies and in silico molecular simulation indicated that the dual layer was covered at the wound site, prevented suture disruption and leakage, inhibited hemorrhage, and reduced postoperative tissue adhesion. Finally, the study results proved that dual-layer multifunctional nanofibrous membrane has a promising therapeutic potential in preventing postoperative pancreatic leakage.

Histopathological Study of the Effects of Dura Adhesive Agents Used in Spinal Surgery Practice on Spinal Epidural Fibrosis in Experimental Animal Model

Objective

Histopathological examination of the effects of Tisseel, Cova, Glubran and Coseal, which are used for sealing purposes in spinal surgery practice, on epidural fibrosis is aimed.

Methods

Forty Sprague Dawley rats were randomly divided into five groups in our study as Group 1 (n=8) control group (Laminectomy); Group 2 (n=8) Cova group (Laminectomy + Cova); Group 3 (n=8) Tissel group (Laminectomy + Tisseel); Group 4 (n=8) Coseal group (Laminectomy + Coseal); and Group 5 Glubrane group (Laminectomy + Glubrane). Control group was only applied laminectomy. After laminectomy to other groups, Cova was applied to the 2nd group, Tissel to the 3rd group, Coseal to the 4th group and Glubran to the 5th group in surgical fields. After the rats were monitored in separate cages for 6 weeks after the operation, the relevant spinal level was extracted and the samples were examined histopathologically and the results were evaluated statistically.

Results

It was found that there was a statistically significant difference in Tisseel and Glubran groups in terms of fibrosis grading compared to the control group, and this had a positive effect on fibrosis. Compared to the control group, there was no statistically significant difference on fibrosis in Cova and Coseal groups.

Conclusion

As dura adhesive agents used in spinal surgery practice did not increase spinal epidural fibrosis statistically significantly, we concluded that these products can be used safely during spinal surgery if necessary.

The effectiveness of spatially cross-linked polymer in the postoperative epidural fibrosis prevention: an experimental study

Introduction. Epidural fibrosis is an urgent problem in modern spinal surgery and orthopedics. The formation of connective tissue in the epidural space after performing surgical interventions on the spinal column inevitably leads to adhesion of the latter to the dura mater and compression of neural structures, followed by the formation of clinical and neurological symptoms. The  search for literary sources in domestic and foreign scientific databases has demonstrated the presence of several works studying the effectiveness of barrier methods for preventing the development of epidural fibrosis. It should be noted that the results of these studies are ambiguous and largely contradictory.

The purpose was to study the effectiveness of using a spatially cross-linked polymer in the postoperative lumbar epidural fibrosis prevention in an experiment.

Materials and methods. The study included 26 male Wistar rats (average body weight 338.5±9.07 g), which were divided into two groups: Group I (control, n = 12): animals underwent laminectomy at the level of vertebral bodies LVII – SI  without application of spatially crosslinked polymer; Group II (experimental, n = 14): animals underwent laminectomy at the level of vertebral bodies LVII – SI  followed by application of a spatially cross-linked polymer to the dura mater. The morphological and instrumental parameters were studied.

Results. Significant differences were noted in the severity of epidural fibrosis (χ2 = 14.846, p = 0.003), the number of newly formed vessels (F = 14.371, p<0.001), the number of fibroblasts (F = 11.158, p<0.001), as well as in the severity of vertebral stenosis channe l according to multislice computed tomography (χ2 = 17.207, p=0.002) between the control and experimental groups of animals.

Conclusion. Application of a spatially cross-linked polymer to the dura mater is an effective way to prevent the development of postoperative epidural fibrosis.

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.

Inflammation by activated macrophage-like THP-1 cells increases human dura mater cell adhesion with alteration of integrin α2 β1 and matrix metalloproteinase

This study was designed to investigate (i) extracellular matrix to specify adhesive substrates to human dura mater cell (hDMC); (ii) the alteration on adhesion-related molecules in hDMC; and (iii) secreted matrix metalloproteinases (MMPs) linked with extracellular matrix remodeling after exposure to inflammation. The hDMC was cultured from human dura mater tissue, and the studies were performed with hDMC after co-culturing with macrophage like THP-1 cells (Mϕ). The adhesion of co-cultured hDMC through collagen I increased 6.4-fold and through collagen IV increased 5.0-fold compared with the adhesion of naïve cells (p < 0.001). Integrin subtype α₂ β₁ expression was increased 6.3-fold (p < 0.001) and α₁ expression was decreased 2.0-fold (p < 0.001) in the co-cultured cells compared with the naïve cells. Co-culturing induced significant increases in MMP-1 (13.9-fold, p < 0.01), MMP-3 (7.6-fold, p < 0.01), and VEGF (VEGF: 3.8-fold, p < 0.05) expression and decreases in MMP-9 (0.1-fold, p < 0.01) compared with the sum of naïve hDMC and Mϕ values. Increased hDMC adhesion under inflammatory conditions is caused by an increased cellular affinity for collagen I and IV mediated by increased hDMC levels of integrin subtype α₂ β₁ and environmental MMP-1, -3 and decreased MMP-9. Selective integrin subtype α₂ β₁ inhibition assay showed 37.8% and 35.7% reduction in adhesion of co-cultured hDMC to collagen I (p < 0.001) and IV (p = 0.057), respectively. The present study provides insight into the pathological conditions related to dura mater adhesion in inflammation. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 9999:1-11, 2019.

Death effects of reveromycin A in normal and disease-associated cells of the joint

Earlier work in our laboratory demonstrated that naturally occurring reveromycin A (Rev A) causes apoptosis in osteoclasts without accompanying necrosis. Rev A death effects in both normal and diseased joint cells were investigated in this study. A dose of 10 μM Rev A did not cause apoptosis nor necrosis in monolayer chondrocytes, even at pH 6.8, a pH mimicking that of an inflamed joint. In contrast, at the acidic pH Rev A did induce significant apoptosis (fourfold increase at 48 h of treatment, P < 0.005) in normal synoviocytes without accompanying necrosis. Western blot of the normal synoviocyte proteins revealed that cytochrome c levels were not significantly changed over the time course of treatment nor did caspase 8 activity increase; therefore, Rev A appears to exert this apoptotic effect through a mechanism independent of the classical intrinsic and extrinsic pathways. Fibroblast-like synoviocytes isolated from rheumatoid arthritis patients (RAFLS) as well as normal human fibroblast-like synoviocytes (NHFLS), cells known to play key roles in arthritic joint pathology, were also subjected to Rev A treatment at both physiologic and acidic pH's. Neither apoptosis nor necrosis was induced in either RAFLS or NHFLS. Parallel mitomycin C treatment of NHFLS induced both apoptosis and necrosis. Comparative structure-activity analyses of Rev A and mitomycin C revealed that Rev A is less likely to cross the cell membrane at near neutral pH. Collectively the data reveal that a physiological dose of Rev A under acidic conditions induces normal synoviocytes to undergo apoptosis while pathologic fibroblast-like synoviocytes are resistant to apoptosis and necrosis.

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.

Local application of rapamycin reduces epidural fibrosis after laminectomy via inhibiting fibroblast proliferation and prompting apoptosis

Background

Epidural fibrosis is a common complication after laminectomy. It is associated with intractable lower back pain and additional complications. To date, no study has evaluated whether the local application of rapamycin (RAPA) can inhibit fibroblast proliferation and reduce epidural scar adhesion after laminectomy. The results of the present study showed that the local application of RAPA reduces epidural fibrosis after laminectomy in rats.

Methods

In this study, 32 male Sprague-Dawley rats were randomly divided into four groups (0.2 mg/ml RAPA-treated group, 0.1 mg/ml RAPA-treated group, 0.05 mg/ml RAPA-treated group and physiological saline group). Laminectomy was performed at the level of lumbar segment 1 to 2, and different concentrations of RAPA or saline were applied to the laminectomy sites for 10 min. Four weeks after laminectomy, the rats were sacrificed, and the degrees of epidural adhesion in each group were evaluated. Macroscopic assessment, analysis of hydroxyproline content, and histological analysis were used to determine the therapeutic effect of the local application of RAPA on the inhibition of fibroblast proliferation and the reduction of epidural fibrosis after laminectomy. Next, we cultured fibroblasts from epidural scar tissues of rats that had undergone laminectomy. Fibroblasts were exposed to the indicated concentrations of RAPA, and western blotting and TUNEL assays were used to assess the effects of RAPA on inhibiting fibroblasts proliferation and promoting fibroblast apoptosis.

Results

The results of macroscopic assessments, analysis of hydroxyproline content, and histological analyses indicated that RAPA significantly inhibited fibroblast proliferation and reduced epidural fibrosis in the treated groups in the rat model. The western blotting results indicated that the expression levels of the pro-apoptotic proteins cleaved-PARP and Bax were up-regulated, whereas those of Bcl-2 were reduced. TUNEL assay indicated that the apoptosis rates of fibroblasts were significantly increased after exposure to the indicated concentrations of RAPA.

Conclusions

The local application of RAPA reduced epidural fibrosis after laminectomy by inhibiting the proliferation of fibroblasts, stimulating their apoptosis, and decreasing collagen synthesis. This protocol may be used in new clinical treatment strategies to reduce epidural fibrosis after laminectomy.

An Experimental Study of Histopathologic Effects of Hemostatic Agents Used in Spinal Surgery

OBJECTIVE

To evaluate and compare the histopathologic effects of various hemostatic agents used in spinal surgery on an experimental laminectomy model in rats.

METHODS

There were 110 rats randomly allocated into 11 groups, including sham, control, AnkaferdBlood Stopper (herbal hemostatic), SeraSeal (agar and bovine factor proteins), FLOSEAL (gelatin granules and thrombin), SURGIFLO (gelatin paste), HELITENE (absorbable collagen), Beriplast (fibrin sealant containing fibrinogen, factor XIII, and thrombin), TISSEEL (fibrin sealant), BLOODCARE (hemostatic powder), and SURGICEL (oxidized cellulose polymer) groups. Hemostatic agents were applied on the epidural region after laminectomy was performed until the identification of dura mater and nerve root. After a follow-up period of 12 weeks, rats were sacrificed, and histologic sections were performed proximal and distal to laminectomy zone. Groups were histopathologically compared in terms of chronic inflammation, fibrosis, and vascularization.

RESULTS

There was no difference between groups in terms of acute inflammation (P = 0.159). Chronic inflammation was more remarkable in the herbal hemostatic group (P = 0.036), and there was severe fibrosis in absorbable collagen hemostatic, fibrin sealant, and powder hemostatic agent groups (P < 0.001). Vascularity was more obvious in herbal hemostatic; fibrin sealant; absorbable collagen; fibrin sealant containing fibrinogen, factor XIII, and thrombin; hemostatic powder; and oxidized cellulose polymer groups (P < 0.001).

CONCLUSIONS

Hemostatic agents can cause notable histopathologic alterations, including inflammation, fibrosis, and vascularity. In this context, flowable hemostats such as gelatin granules and thrombin or gelatin paste seem to provide more promising results in spinal surgery.

Efficacy and Safety of Sodium Hyaluronate with 1,4-Butanediol Diglycidyl Ether Compared to Sodium Carboxymethylcellulose in Preventing Adhesion Formation after Lumbar Discectomy

OBJECTIVE

Epidural injection of hyaluronic acid may prevent adhesion formation after spine surgery, but the compounds used to stabilize hyaluronidase could interfere with its anti-adhesion effects. The present study was conducted as a clinical trial to evaluate the efficacy and safety of an experimental medical gel in preventing adhesion formation.

METHODS

This study was designed as a multicenter, randomized, double-blind, and comparative controlled clinical trial with an observation period of 6 weeks. Subjects were randomly assigned into two groups: group A with sodium hyaluronate + 1,4-butanediol diglycidyl ether (BDDE) and group B with sodium hyaluronate + sodium carboxymethylcellulose (CMC). Visual analogue scale (VAS) of back and leg pain and the Oswestry disability index (ODI) and scar score ratings were assessed after surgery.

RESULTS

Mean scar grade was 2.37±1.13 in group A and 2.75±0.97 in group B, a statistically significant difference (p=0.012). VAS of back and leg pain and ODI scores decreased significantly from baseline to 3 and 6 weeks postoperatively in both groups (p<0.001). However, VAS and ODI scores were not statistically different between groups A and B at baseline or at 3 and 6 weeks after operation (p>0.3). The number of adverse reactions related to the anti-adhesion gels was not statistically different (p=0.569), but subsequent analysis of nervous adverse reactions showed group B was superior with a statistically difference (p=0.027).

CONCLUSION

Sodium hyaluronate with BDDE demonstrated similar anti-adhesion properties to sodium hyaluronate with CMC. But, care should be used to nervous adverse reactions by using sodium hyaluronate with BDDE.

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.

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.

Calcium channel blockers in reduction of epidural fibrosis and dural adhesions in laminectomy rats

OBJECTIVE

To investigate the effect of verapamil on the prevention of epidural fibrosis in laminectomy rats.

METHODS

A controlled double-blinded study was conducted in sixty healthy adult Wistar rats that underwent laminectomy at the L1-L2 levels. All rats were divided randomly into three groups according to the treatment method, with 20 in each group: (1) VP treatment group; (2) vehicle treatment group; and (3) sham group (laminectomy without treatment). All rats were killed 4 weeks post-laminectomy. The hydroxyproline content, Rydell score, vimentin cells density, fibroblasts density, inflammatory cells density and inflammatory factors expressions were evaluated.

RESULTS

The histological evaluation showed less epidural scar adhesions in verapamil group than other two groups. The hydroxyproline content, Rydell score, vimentin cells density, fibroblasts density, inflammatory cells density and inflammatory factors expressions all suggested better results in verapamil group than other two groups.

CONCLUSION

Topical application of verapamil could inhibit fibroblasts proliferation and TGF-β1 and IL-6 expressions and prevent epidural scar adhesion in post-laminectomy rat model.

Reduction in postlaminectomy epidural adhesions in sheep using a fibrin sealant-based medicated adhesion barrier

Epidural adhesion formation is believed to be a central governing factor in the prevalence of pain after spinal surgery and is regarded as being the primary instigator of neural tethering, leading to complications during revision surgery. In this study, we assess the effectiveness and safety of fibrin sealant supplemented with tributyrin, termed Medicated Adhesion Barrier (MAB), as an alternative means of reducing the incidence of posterior spinal epidural adhesion formation. Laminectomy defects in sheep were treated with MAB, fibrin sealant alone, ADCONGel, or remained untreated. At 12 weeks postoperatively, the extent of fibrosis and epidural adhesion formation was evaluated using magnetic resonance imaging (MRI), peel-off testing, and histological examination. Initial invitro analysis revealed that tributyrin was retained in fibrin gel in a time-dependent manner and was an effective inhibitor of fibroblast proliferation. Treatment of sheep with MAB significantly reduced both the prevalence (p < 0.05) and tenacity (p < 0.05) of epidural adhesions. The effectiveness of MAB in preventing epidural adhesions was found to be comparable with that of ADCONGel. No adverse events were reported after the use of MAB. The MAB preparation seems to be an effective resorbable barrier for the prevention of epidural adhesions.

Use of pimecrolimus to prevent epidural fibrosis in a postlaminectomy rat model

OBJECT

Epidural fibrosis is the scar tissue formed over the dura mater after a laminectomy. Extensive epidural fibrosis may be an important underlying cause of failed back syndrome. Pimecrolimus, an ascomycin derivative, is one of the new classes of immunomodulating macrolactams and was specifically developed for the treatment of inflammatory diseases. This study examined the preventive effects of the local application of pimecrolimus in minimizing spinal epidural fibrosis in a rat laminectomy model.

METHODS

Thirty Wistar rats were divided into 3 equal groups: control, mitomycin C (MMC), and pimecrolimus groups. Each rat underwent a laminectomy at the L-3 lumbar level. In the experimental groups, a cotton pad soaked with MMC (0.5 mg/ml) or 5 mg pimecrolimus was placed on the exposed dura mater. No treatment was performed in the control group rats. Thirty days after surgery, the rats were killed and the dura mater thickness, epidural fibrosis, and arachnoidal involvement were quantified.

RESULTS

The mean dura thickness was measured at 9.28 +/- 3.39 microm in the MMC group and at 8.69 +/- 2.32 microm in the pimecrolimus group, compared with 14.70 +/- 4.14 microm in the control group. In addition, the epidural fibrosis and arachnoidal involvement were reduced significantly in the treatment groups compared with the control group.

CONCLUSIONS

In this animal model, it was shown that locally applied pimecrolimus effectively reduces epidural fibrosis and dural adherence in rats that underwent lumbar laminectomy. Mitomycin C was equally effective as pimecrolimus in reducing epidural fibrosis and dural adherence in this study.

Mitomycin C, 5-fluorouracil, and cyclosporin A prevent epidural fibrosis in an experimental laminectomy model

This study examined the preventive effects of the local application of mitomycin C (MMC), 5-fluorouracil (5-FU), and cyclosporine A (CsA) in minimizing spinal epidural fibrosis in a rat laminectomy model. Thirty-two 2-year-old male Wistar albino rats, each weighing 400 +/- 50 g, were divided into four equal groups: sham, MMC, 5-FU, and CsA. Each rat underwent laminectomy at the L5-L6 lumbar level. Cotton pads (4 x 4 mm2) soaked with MMC (0.5 mg/ml), 5-FU (5 ml/mg), or CsA (5 mg/ml) were placed on the exposed dura for 5 min. Thirty days after surgery, the rats were killed and the epidural fibrosis, fibroblast density, inflammatory cell density, and arachnoid fibrosis were quantified. The epidural and arachnoid fibroses were reduced significantly in the treatment groups compared to the sham group. Fibroblast cell density and inflammatory cell density were decreased significantly in the MMC and 5-FU groups, but were similar in the sham and CsA groups. The decreased rate of epidural fibrosis was promising. Further studies in humans are needed to determine the short- and long-term complications of the agents used here.

Preemptive analgesia with lidocaine prevents Failed Back Surgery Syndrome

Failed Back Surgery Syndrome (FBSS) is commonly encountered in pain-treatment settings in the United States. We tested whether potential key factors in this syndrome, such as extracellular concentrations of excitatory amino acids (EAAs), are increased in the dorsal horn by synaptic release due to unintentional stretch and/or deformation/compression/transection of dorsal spinal structures during surgery. We hypothesized that pharmacological nerve block as a form of preemptive analgesia prior to any insult to dorsal root neurons will prevent an abnormally high increase in extracellular concentrations of EAAs in the dorsal horn and ultimately the establishment of central sensitization during back surgery. The L4 and L5 dorsal roots were cut bilaterally near the spinal cord to provide an adequate model to test for preemptive analgesia. Amino acid concentrations were measured by dorsal horn microdialysis sampling; EAAs aspartate and glutamate were significantly increased by 80% and 65% respectively, as were other amino acids compared to sham control values. Topical application of 1% Lidocaine, a voltage-gated Na(+) channel blocker, for 10 min prior to L4 and L5 bilateral dorsal rhizotomy (BDR) significantly attenuated the increase in EAA concentrations such that their values were not different from sham controls. Behavioral tests demonstrated significant hindlimb mechanical allodynia after BDRs that was significantly attenuated by Lidocaine pretreatment. Thus, Lidocaine pretreatment could offer a safe measure for prevention of chronic pain for back surgical procedures if given by intramuscular injection, topical administration onto spinal nerves and/or the dorsal spinal surface during surgical procedures that include nerve entrapment release, intervertebral disc modification and laminectomies.

Anti-adhesion properties of a thrombin-based hemostatic gelatin in a canine laminectomy model: a biomechanical, biochemical, and histologic study

STUDY DESIGN

An in vivo study on the effects of an agent for scar prevention in a dog laminectomy model.

OBJECTIVE

To examine the anti-adhesion properties of a thrombin-based hemostatic gelatin (FLOSEAL; Baxter International Inc., Deerfield, IL).

SUMMARY OF BACKGROUND DATA

Postlaminectomy dural adhesion sometimes causes symptomatic problems. Although a new type of hemostatic agent, a thrombin-based hemostatic gelatin, has been developed, its effect on postlaminectomy scar prevention is unknown.

METHODS

A 4-level lumbar laminectomy was performed on 11 adult mongrel dogs. There were 2 levels randomly chosen to receive the thrombin-based hemostatic gelatin treatment, while the remaining levels were untreated (control). Dogs were euthanized 8 weeks after surgery. To assess the tenacity of adhesion between the dura and scar, peel-off testing was performed. Gross, biochemical, and histologic analyses were then used to examine the samples.

RESULTS

Peel-off stiffness was significantly decreased in the treatment group (64.8% of the control, P = 0.032; 2-tailed unpaired t test). Histologically, there was significantly less scar tissue formation in the treatment group (P = 0.04). The gross analyses showed a trend toward a smaller amount of scar tissue and tenacity of adhesion between the dura and scar in the treatment group. Biochemically, there was a trend toward a lower collagen cross-links content in the treatment group (P = 0.07).

CONCLUSIONS

The thrombin-based hemostatic gelatin decreases the tenacity of adhesion between the dura and scar at laminectomy sites.