Economic Implications of Dural Tears in Lumbar Microdiscectomies: A Retrospective, Observational Study.

OBJECTIVE: Dural tears (DTs) are a frequent complication after lumbar spine surgery. We sought to determine the incidence of DTs and the related impact on health care expenditures after lumbar discectomies. METHODS: In this retrospective cohort study, all patients with first-time single-level lumbar discectomies at our institution who underwent minimally invasive surgery from 2015 to 2019 were reviewed. Age, sex, weight, height, body mass index, costs, revenues, length of stay, American Society of Anesthesiologists score, Charlson Comorbidity Index, and operative time (OT) were assessed. Exclusion criteria were age <18 years, previous spine surgery, multiple or traumatic disc herniations, and malignant and infectious diseases. RESULTS: The follow-up time was at least 12 months postoperatively. Of 358 patients identified with lumbar discectomies, 230 met the inclusion criteria. Incidence of DTs was 3.5%. Mean costs (P < 0.001), economic loss (P < 0.01), and OT (P < 0.0001) were found to be significantly higher in the DT group compared with the control group of patients without a DT. The revenues were not statistically different between the 2 groups (P > 0.05). Further analysis of the control group by profit and loss revealed significantly higher body mass index (P < 0.05), length of stay (P < 0.0001), and OT (P < 0.0001) in the loss group. CONCLUSIONS: DTs represent a significant socioeconomic burden in lumbar spine surgery and cause severe secondary complications. The impact of DTs on health care expenses is primarily based on significantly higher OT and a higher mean length of stay.

Arachnoid Welding-A Simple and Economical Method of Arachnoid Closure to Prevent Cerebrospinal Fluid Leak.

BACKGROUND: Collection of cerebrospinal fluid (CSF) in the subdural compartment is a major cause of postoperative morbidity, especially for posterior fossa surgeries. Arachnoid closure techniques, including suturing of the arachnoid and use of synthetic sealants, have been described in the literature. However, they are not always feasible or effective and have not been universally adopted. METHODS: We describe the technique of arachnoid welding for a case of brainstem cavernoma. This is a simple, cost-effective, and easily reproducible technique using readily available bipolar cautery kept at a low-current setting. At the end of surgery, the arachnoid leaflets are closely approximated, and bipolar cautery is used to seal the edges together. An illustrative video shows the technical nuances of this procedure. This technique can also be applied for arachnoid closure at other cranial and spinal sites. RESULTS: Arachnoid closure can act as an effective natural barrier to keep CSF in its physiological subarachnoid compartment. It provides an additional barrier to prevent CSF leak. It also prevents morbidity associated with adhesions and arachnoiditis. Proper closure of arachnoid makes durotomy during repeat surgery much easier and avoids injury to the underlying pia. A brief review of related literature shows the benefits of closing the arachnoid before dural closure and the different techniques that have been described so far. CONCLUSIONS: The arachnoid welding technique has a wide application, is easy to learn, and can be used especially for posterior fossa surgeries in which rates of CSF leak are the highest.

Creation of low cost, simple, and easy-to-use training kit for the dura mater suturing in endoscopic transnasal pituitary/skull base surgery.

Training kits for laparoscopes for deep suturing under endoscopes are commercially available; however, previously reported training kits for endoscopic transnasal transsphenoidal pituitary/skull base surgery (eTSS) were not available in the market. Moreover, the previously reported low cost, self-made kit has the drawback of being unrealistic. This study aimed to create a low cost training kit for eTSS dura mater suturing that was as close to real as possible. Most necessary items were obtained from the 100-yen store ($1 store) or from everyday supplies. As an alternative to the endoscope, a stick-type camera was used. Through the assembly of the materials, a simple and easy-to-use training kit was created, which is almost identical to the actual dural suturing situation. In eTSS, a simple and easy-to-use training kit for dural suturing was successfully created at a low cost. This kit is expected to be used for deep suture operations and the development of surgical instruments for training.

Assessment of Meningeal Lymphatics in the Parasagittal Dural Space: A Prospective Feasibility Study Using Dynamic Contrast-Enhanced Magnetic Resonance Imaging.

OBJECTIVE: Meningeal lymphatic vessels are predominantly located in the parasagittal dural space (PSD); these vessels drain interstitial fluids out of the brain and contribute to the glymphatic system. We aimed to investigate the ability of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in assessing the dynamic changes in the meningeal lymphatic vessels in PSD. MATERIALS AND METHODS: Eighteen participants (26-71 years; male:female, 10:8), without neurological or psychiatric diseases, were prospectively enrolled and underwent DCE-MRI. Three regions of interests (ROIs) were placed on the PSD, superior sagittal sinus (SSS), and cortical vein. Early and delayed enhancement patterns and six kinetic curve-derived parameters were obtained and compared between the three ROIs. Moreover, the participants were grouped into the young (< 65 years; n = 9) or older (≥ 65 years; n = 9) groups. Enhancement patterns and kinetic curve-derived parameters in the PSD were compared between the two groups. RESULTS: The PSD showed different enhancement patterns than the SSS and cortical veins (P < 0.001 and P < 0.001, respectively) in the early and delayed phases. The PSD showed slow early enhancement and a delayed wash-out pattern. The six kinetic curve-derived parameters of PSD was significantly different than that of the SSS and cortical vein. The PSD wash-out rate of older participants was significantly lower (median, 0.09; interquartile range [IQR], 0.01-0.15) than that of younger participants (median, 0.32; IQR, 0.07-0.45) (P = 0.040). CONCLUSION: This study shows that the dynamic changes of meningeal lymphatic vessels in PSD can be assessed with DCE-MRI, and the results are different from those of the venous structures. Our finding that delayed wash-out was more pronounced in the PSD of older participants suggests that aging may disturb the meningeal lymphatic drainage.

Assessment of the levels of termination of the conus medullaris and thecal sac in the pediatric population.

PURPOSE: This study assessed the position of the termination of the conus medullaris (the point where the spinal cord tapers to an end) and thecal sac (the sheath of dura mater that surrounds the spinal cord and caudal nerve roots) in a large pediatric population, to characterise the nature of the pediatric Gaussian distribution and assess whether age affected the distribution. The study further aimed to assess the effect of gender on termination positions. METHODS: A total of 520 MRI spine studies of children aged between 1 month and 19 years old were collected from two pediatric tertiary referral centres in the UK and Italy. Studies with pathological findings were excluded, and normal scans were found using keyword search algorithms on a database of radiologists' reports. The reported scans were individually assessed and reviewed by two experienced neuroradiologists. The termination points of the conus medullaris and thecal sac were determined for each study. Local IRB approvals were sought. RESULTS: The results showcased a Gaussian distribution in both conus medullaris (r=0.8997) and thecal sac termination levels (r=0.9639). No statistically significant results were noted with increasing age for the termination positions of the conus medullaris or thecal sac (p = 0.154, 0.063). No statistical significance was observed with gender variation with either anatomical landmark. A weak positive correlation was observed between the termination levels of the conus medullaris and the thecal sac (r=0.2567) CONCLUSION: Termination levels across all pediatric age range followed a Gaussian distribution. Knowledge of normal termination levels has relevant clinical implications, including the assessment of patients with suspected spinal dysraphism.

Cost-Effectiveness Analysis of the Application of a Porcine-Derived Fibrin Sealant for the Treatment of Cerebrospinal Fluid Leak in China.

PURPOSE: This study aimed to evaluate the cost-effectiveness of a porcine-derived fibrin sealant (PFS) for treating cerebrospinal fluid (CSF) leaks in cranial surgery compared with sutures alone from the perspective of public hospital management in China. METHODS: A decision tree model of cranial surgery patients with intraoperative CSF leak was constructed in R 3.6.3. The cost-effectiveness of using PFS with dural sutures was compared versus using sutures alone. Efficacy and safety data were obtained from a randomized controlled, single-blinded clinical trial that enrolled 200 patients (NCT03110783). Effectiveness was measured as the success rate of CSF leak treatment and the rate of postoperative complication. Hospital procurement costs were used to provide cost measurements from the hospital administrator's perspective. FINDINGS: The PFS strategy had a higher success rate of CSF leak treatment (97.81% vs 49.21%) and a lower complication rate (9.49% vs 14.29%), based on results from the clinical trial. Using PFS also resulted in cost savings amounting to $374.97 in additional intraoperative CSF leak repairs ($18.07 vs $393.04) and $66.68 in postoperative complication treatment ($131.90 vs $198.58). Both one-way sensitivity analysis and probabilistic sensitivity analysis confirmed that the model results were stable against input variations. IMPLICATIONS: The decision tree analysis revealed that using PFS in conjunction with sutures was associated with improved clinical performance and lower overall costs. PFS in combination with sutures is the dominant strategy for treating CSF leak from the perspective of hospital decision-makers.

Posttraumatic leptomeningeal cyst capsule as a cost-free autograft for its repair: case illustrated technical reports.

The surgical treatment of traumatic leptomeningeal cyst (LMC) is repair of the dural defect with or without cranioplasty. The dural substitutes used are either autografts (which may not be enough) or artificial grafts (which are foreign-body implantations and which also may be too expensive in a low-resource practice). In this report from a developing country, we present the surgical description of the use of the cyst capsule as a cost-free autologous graft in the surgical repair of the dural defects of two cases of traumatic leptomeningeal cyst.

Dural Substitutes Differentially Interfere with Imaging Quality of Sonolucent Transcranioplasty Ultrasound Assessment in Benchtop Model.

BACKGROUND: Sonolucent cranioplasty implants were recently introduced into clinical practice and tested for use with transcranioplasty ultrasound (TCUS). In situations where dural substitutes (DSs) are needed during closure, such as in extracranial-intracranial bypass, it is unclear if the DS influences the imaging quality of TCUS. The aim of this study was to assess the influence of DSs on imaging quality during TCUS assessment with sonolucent cranioplasty. METHODS: A tofu vascular brain model was constructed with a ClearFit implant in between 2 layers of tofu. Injection of saline solution through a 6-F Envoy DA XB endovascular catheter (6-F Envoy DA XB) inserted into the deeper tofu layer mimicked an intracranial vessel. TCUS image quality, including Doppler, with 4 different DSs (DuraGen, Durepair, DuraMatrix-Onlay, DuraMatrix Suturable) placed under the cranioplasty was compared against a control by 2 examiners. A literature search of MEDLINE and EMBASE was conducted to find previous reports of acoustic properties of DSs. RESULTS: TCUS assessment including Doppler was feasible with the model in longitudinal and axial planes, and the pulsatile particle injection was visualized in real time. DuraGen and Durepair showed Doppler quality and picture detail comparable to the control, while the DuraMatrix-Onlay and DuraMatrix Suturable were inferior to the control. The literature search yielded only 1 previous report on acoustic properties of DSs. CONCLUSIONS: DSs interfere differentially with imaging quality during TCUS assessment. However, these results are based on a benchtop model and need to be further assessed in the clinical setting.

Dural Leak: Is It Deterrent to Outcomes in Spine Surgery?: 10 Years Retrospective Analysis of Incidence, Management Protocol, and Surgical Outcomes.

STUDY DESIGN: Retrospective case-control study. OBJECTIVES: To review the incidence of dural leaks, evaluate the efficacy of primary closure of durotomy and to study its effect on clinical outcome. The secondary aim is to classify the dural leaks and proposing a treatment algorithm for dural leaks. SUMMARY OF BACKGROUND DATA: Dural leaks are described as one of the fearful complications in spine surgery. Literature evaluating the actual incidence, ideal treatment protocol, efficacy of primary repair techniques and its effects on long-term surgical outcomes are scanty. METHODS: It was a retrospective analysis of 5390 consecutively operated spine cases over a period of 10 years. All cases were divided into two groups-study group (with dural leak-255) and control group (without dural leak-5135). Dural leaks were managed with the proposed treatment algorithm. Blood loss, surgical time, hospital stay, time for return to mobilization, pain free status, and clinical outcome score (ODI, VAS, NDI, and Wang criteria) were assessed in both groups at regular intervals. The statistical comparison between two groups was established with chi-square and t-tests. RESULTS: The overall incidence of dural leaks was 4.73% with highest incidence in revision cases (27.61%). There was significant difference noted in mean surgical blood loss (P 0.001), mean hospital stay (P 0.001), time to achieve pain-free status after surgery, and return to mobilization between two groups. However, no significant difference was noted in operative time (P 0.372) and clinical outcome scores at final follow-up between the two groups. CONCLUSION: Primary closure should be undertaken in all amenable major dural leak cases. Dural leaks managed as proposed by the author's treatment algorithm have shown a comparable clinical outcome as in patients without dural leaks. Dural leak is a friendly adverse event that does not prove a deterrent to long-term clinical outcome in spine surgeries. LEVEL OF EVIDENCE: 4.

Incidental Durotomy During Endoscopic Stenosis Lumbar Decompression: Incidence, Classification, and Proposed Management Strategies.

OBJECTIVE: We sought to review the types of incidental durotomies (IDs) that occurred during the endoscopic stenosis lumbar decompression through interlaminar approach (ESLD) and discuss the management strategies according to our classification. METHODS: A retrospective evaluation was performed for patients with spinal stenosis who underwent ESLD. Out of 330 patients, 27 patients of ID were clinically evaluated preoperatively and postoperatively on the basis of a visual analog scale score, Oswestry Disability Index, and MacNab's criteria. ID patterns are classified according to the size, location, and involvement of neural elements. Intraoperative and postoperative surgical management was evaluated. RESULTS: Intraoperative incidence of ID was 8.2%. According to lumbar levels, 11 (40.7%) occurred at L3-4, 12 (44.4%) at L4-5, and 4 (14.8%) at L5-S1 ID cases. IDs were divided into 4 types: 29.6% are type 1, 70% are type 2, 7.4% are type 3, and 3.7% are type 4. Overall for mean and standard deviation preoperative, 1 week postoperative, 3 months, and final follow-up for visual analog scale are 7.6 ± 1.4, 3.3 ± 1.1, 2.6 ± 1.1, and 1.9 ± 1.3, and for Oswestry Disability Index are 74.5 ± 9.0, 32.3 ± 9.4, 27.3 ± 7.2, and 24.4 ± 6.5 after patch blocking dura repair of ID. CONCLUSIONS: ID is a more common surgical complication in ESLD compared with the transforaminal approach. The endoscopic patch blocking dura repair technique should be considered in type 1 to type 3A of dura tear with good prognosis and clinical outcome. Consideration is made for conversion to open repair in types 3B, 3C and 4 dura tears with fair to poor outcome.

The True Effect of a Lumbar Dural Tear on Complications and Cost.

STUDY DESIGN: Retrospective database analysis. OBJECTIVE: The aim of this study was to match risk factors for complications in patients who did and did not sustain a dural tear while undergoing posterior lumbar spine surgery and compare local and systemic complications. SUMMARY OF BACKGROUND DATA: Current data do not adequately define whether the event of sustaining an isolated dural tear increases the risk for postoperative complications while controlling for other confounding risk factors. METHODS: The PearlDiver Database was queried for patients who underwent posterior lumbar spine decompression and/or fusion for degenerative pathology. Patients with and without dural tears were 1:2 matched based on demographic variables and comorbidities. Complications, cost, length of stay (LOS), and readmission rates were analyzed. RESULTS: The 1:2 matched cohort included 9038 patients with a dural tear and 17,340 patients without a dural tear. All complications assessed were significantly higher in the dural tear group (P < 0.03). Venothromboembolic (VTE) events occurred in 1.3% of patients with a dural tear and 0.9% of patients without a dural tear (odds ratio [OR] 1.46, P < 0.0001). Meningitis occurred in 25 patients (0.3%) with a dural tear and eight patients (<0.1%) without a dural tear (OR 6.0, P < 0.0001). Patients with a dural tear had 120% higher medical costs, 200% greater LOS, and were two times more likely to be readmitted (P < 0.0001). CONCLUSION: Sustaining a dural tear while undergoing posterior lumbar spinal decompression and/or fusion for degenerative pathology significantly increased the risk of complications and increased length of stay, risk of readmission, and overall 90-day hospital cost. Dural tears specifically increased the risk of a VTE complication by 1.46 times and meningitis by six times; these are important complications to have a high degree of suspicion for in the setting of durotomy, as they can lead to significant morbidity for the patient. LEVEL OF EVIDENCE: 3.

Orthopedic versus Neurosurgery-Understanding 90-Day Complications and Costs in Patients Undergoing Elective 1-Level to 2-Level Posterior Lumbar Fusions by Different Specialties.

BACKGROUND: Lumbar fusions are routinely performed by either orthopedic or neurologic spine surgeons. Controversy still exists as to whether a provider's specialty (orthopedic vs. neurosurgery) influences outcomes. METHODS: The 2007-2015Q2 Humana Commercial Database was queried using Current Procedural Terminology codes (22612, 22614, 22630, 22632, 22633 and 22634) to identify patients undergoing elective 1-to-2 level posterior lumbar fusions (PLFs) with active enrollment up to 90 days after procedure. Ninety-day complication rates were calculated for the 2 specialties. The surgical and 90-day resource utilization costs for the 2 groups were compared, by studying average reimbursements for acute-care and post-acute-care categories. Ninety-day complications and costs were compared using multivariable logistic and linear regression analyses. RESULTS: A total of 10,509 patients (5523 orthopedic and 4986 neurosurgery) underwent an elective 1-to-2 level PLF during the period. With the exception of a significantly lower odds of wound complications (odds ratio, 0.81) and a higher odds of dural tears (odds ratio, 1.29) in elective PLFs performed by orthopedic surgeons, no statistically strong differences were seen in 90-day complication rates between the 2 groups. Total 90-day costs were also similar between orthopedic surgeons and neurosurgeons, with the only exception being that surgeon reimbursement was lower for orthopedic surgery versus neurosurgery ($1202 vs. $1372; P < 0.001). CONCLUSIONS: It seems that a provider's specialty does not largely influence 90-day surgical outcomes and costs after elective PLFs. The results of the study promote the formation and acceptance of dual training pathways for entry into spine surgery.

Assessment of Dural Ectasia Using Computed Tomodensitometry as a Criterion in Marfan Syndrome.

OBJECTIVE: The aim of this study was to reevaluate dural ectasia criteria in Marfan syndrome patients fulfilling the revised Ghent criteria. METHODS: Lumbar computed tomography scans of 19 Marfan patients and 30 matched control subjects were retrospectively assessed. Dural sac ratio (DSR), nerve root sleeve diameter, pedicle width, and a scalloping or meningocele presence were each assessed by 2 readers blinded from the diagnosis. Mann-Whitney-Wilcoxon tests compared the patient and control groups. Receiver operating characteristic curve analysis and multivariate models determined the optimal cutoff value. RESULTS: A DSR value greater than 0.69 at L5 (DSR-L5) such as L4 scalloping of more than 2.65 mm (scall-L4) and 6 or more vertebrae showing a scalloping of more than 3 mm (6-scall) were found very specific but with limited sensitivity. Multivariate model combining DSR-L5 + scall-L4 showed good positive predictive value, whereas model combining DSR-L5 + 6-scall showed good negative predictive value. CONCLUSIONS: Assessment of DSR and vertebral scalloping allows valuable depiction of dural ectasia in Marfan syndrome patients.

A low cost dural closure simulation model for tomorrow's spinal neurosurgeons.

Introduction: We present a low cost model that can be used to improve a trainee's skills in spinal dural closure. Development of microsurgical skills in a simulated environment provides a safe environment in which patients are protected. We argue that this is likely to improve the quality of dural closure, especially for surgeons early in their training and may lead to a commensurate reduction in post-operative CSF leak. Method: In our model, two consultant spine surgeons assessed the ability of participants to close the spinal dura. Participants were scored both quantitatively (time taken to complete the task) and qualitatively under the category of "surgical performance"- assessed by video and inspection of the closed dural substitute. Results: The cohort under assessment included senior and newly appointed consultants, clinical fellows and thirteen specialty trainees. 10 trainees were assessed a second time and a significant majority improved on both domains: 8 (80%) were faster on their second attempt; surgical performance scores also improved in the majority of trainees (90%). Conclusion: Our results, albeit with small numbers, show that a large proportion of trainees improve with practice with a reduction in overall task time and an improvement in surgical performance. Our model is cost-effective and easy to reproduce: simulation need not be an expensive exercise. This study further validates the use of simulation in modern neurosurgical training.

In-vivo assessment of osseous versus non-osseous transmission pathways of vibratory stimuli applied to the bone and the dura in humans.

BACKGROUND: Bone conduction (BC) is an alternative to air conduction (AC) for stimulation of the inner ear. Stimulation for BC can occur directly on the skull bone, on the skin covering the skull bone, or on soft tissue (i.e., eye, dura). All of these stimuli can elicit otoacoustic emissions (OAE). This study aims to compare OAEs generated by different combinations of stimuli in live humans, including direct stimulation of the intracranial contents via the dura, measured intraoperatively. METHODS: Measurements were performed in five normal-hearing ears of subjects undergoing a neurosurgical intervention with craniotomy in general anesthesia. Distortion product OAEs (DPOAEs) were measured for f2 at 0.7, 1, 2, 3, 4, and 6 kHz with a constant ratio of the primary frequencies (f2/f1) of 1.22. Sound pressure L1 was held constant at 65 dB SPL, while L2 was decreased in 10 dB steps from 70 to 30 dB SPL. A DPOAE was considered significant when its level was ≥6 dB above the noise floor. Emissions were generated sequentially with different modes of stimulation: 1) pre-operatively in the awake subject by two air-conducted tones (AC-AC); 2) within the same session preoperatively by one air- and one bone-conducted tone on the skin-covered temporal bone as in audiometry (AC-BC); 3) intra-operatively by one air-conducted tone and one bone-vibrator tone applied directly on the dura (AC-DC). A modified bone vibrator (Bonebridge; MED-EL, Innsbruck, Austria) was used for BC stimulation on the dura or skin-covered mastoid. Its equivalent perceived SPL was calibrated preoperatively for each individual by psychoacoustically comparing the level of a BC tone presented to the temporal region to an AC tone at the same frequency. Simultaneously with the DPOAEs, vibrations at the teeth were measured with an accelerometer attached using a custom-made holder. RESULTS: It was possible to record DPOAEs for all three stimulation modes. For AC-DC, DPOAEs were not detected above the noise floor below 2 kHz but were detectable at the higher frequencies. The best response was measured at or above 2 kHz with L2 = 60 dB SPL. The acceleration measured at the teeth for stimulation on the dura was lower than that for stimulation on the bone, especially below 3 kHz. CONCLUSION: We demonstrate a proof-of-concept comparison of DPOAEs and teeth acceleration levels elicited by a bone vibrator placed either against the skin-covered temporal bone, as in audiometry, or directly against the dura mater in patients undergoing a craniotomy. It was demonstrated that DPOAEs could be elicited via non-osseous pathways within the skull contents and that the required measurements could be performed intra-operatively.

Incidental Durotomy in Open Versus Tubular Revision Microdiscectomy: A Retrospective Controlled Study on Incidence, Management, and Outcome.

STUDY DESIGN: Retrospective case-control study. OBJECTIVE: To compare the incidence, management, and outcome of incidental durotomy in revision microdiscectomy with open and minimal-access surgery. SUMMARY OF BACKGROUND DATA: Incidental durotomy occurs with a variable incidence of 3%-27% in spine surgery. The highest rate occurs in revision microdiscectomy. The intraoperative and postoperative management of dural tears varies in the literature and the definite impact on clinical outcome has to be clarified. METHODS: This is a retrospective study of medical records of 135 patients who underwent revision microdiscectomy, divided into 2 subgroups: OPEN (n=82) versus minimal-access surgery (MINI, n=53). Occurrence of intraoperative dural tears, intraoperative and postoperative management of durotomy, and clinical outcomes, according to MacNab criteria, were retrospectively examined. Statistical comparisons for categorical values between groups were accomplished using the 2-tailed Fisher exact test. P-values <0.05 were considered to be statistically significant. RESULTS: The incidence of durotomy in group OPEN was 19.5% (n=16/82) and in group MINI 17.0% (n=9/53) (P=0.822). The majority of durotomies (23/25) were repaired with an absorbable fibrin sealant patch alone. Postoperative cerebrospinal fluid fistula occurred only in 1 case of the OPEN group and was treated with lumbar drainage without the need for a reoperation. Patients with durotomy of the MINI group tended to have better outcome compared with those of the OPEN group without being statistically significant. CONCLUSIONS: The incidence of durotomy and postoperative cerebrospinal fluid fistula in lumbar revision microdiscectomy does not significantly differ between minimal-access and standard open procedures. The application of a fibrin sealant patch alone is an effective strategy for dural repair in revision lumbar microdiscectomy.

Is the use of hemostatic matrix (Floseal) and alkylene oxide copolymer (Ostene) safe in spinal laminectomies? Peridural fibrosis assessment.

OBJECTIVE: Failed Back Syndrome (FBS) is unacceptable relief of pain or recurrence of symptoms in patients after spinal surgery, such as laminectomy. One possible cause of FBS is peridural fibrosis (PF). PF is the overproduction of scar tissue adjacent to the dura mater. Bleeding can cause PF after laminectomy. Ostene is an alkylene oxide copolymer material used to stop bleeding from bony surfaces. Floseal is a gelatin thrombin matrix sealant used to assist fibrin formation and to promote coagulation. METHODS: Total of 32 female Sprague-Dawley rats were evenly allotted to 4 experimental groups: laminectomy only, laminectomy + Ostene (Baxter International, Inc., Deerfield, IL, USA), laminectomy + Floseal (Baxter International, Inc., Deerfield, IL, USA), and laminectomy + Adcon-L (aap Implantate AG, Berlin, Germany). After performing total laminectomy, agents were placed over dura mater. Spinal column of test subjects was harvested 6 weeks after laminectomy. Histopathological examination of samples was based on Masson's trichrome and hematoxylin and eosin staining. PF observed in the groups was graded using system previously described by He et al. Statistically significant p value was defined as p < 0.005. RESULTS: Present study revealed that Adcon-L, Ostene, and Floseal groups had reduced PF compared with laminectomy only group (p = 0.001). Comparison of Ostene and Floseal groups with Adcon-L group yielded no significant difference. CONCLUSION: Reoperation as result of FBS has greater risk and often has poor outcome; surgeons must take precautions to avoid FBS, such as careful selection of appropriate patient and operation technique. Ostene and Floseal may be applied and left in the operation field safely during laminectomy to reduce occurrence of PF after procedure.