Effectiveness and handling characteristics of a three-layer polymer dura substitute: a prospective multicenter clinical study

The comparison of the watertight and non-watertight dural closure in supratentorial craniotomy: A single-institute 10-year experience with 698 patients

Watertight dural closure (WTDC) is considered crucial by many neurosurgeons in cranial base surgery, infratentorial craniotomy, and spinal intradural procedure. Whether WTDC also reduce complications remains controversial in supratentorial craniotomy. The objective of this study is to investigate the relationship between WTDC and CSF-related complications in supratentorial craniotomy for the resection of space-occupying lesions. A retrospective analysis of patients who suffered from intracranial space-occupying lesions at Beijing Ditan Hospital between January 2011 and December 2021 was conducted. A total of 698 cases were reviewed with attention to the operative approach, subgaleal fluid collection, wound healing impairment, postoperative infection, and post-craniotomy headaches. The study included a total of 423 patients with WTDC and 275 patients without WTDC. Patients without WTDC had a significantly higher rate of infection (10.9% vs 4.5% with WTDC, P = .001). The rate of subgaleal fluid collection was 9.7% in the WTDC group and 11.3% in the non-WTDC group, but this difference was not statistically significant (P = .502). They suffered from a greater incidence of post-craniotomy headaches in the WTDC group (13.5% vs 9.5% in the non-WTDC group), but without statistical significance (P = .109). We also found no difference in wound healing impairment (P = .719). There is less postoperative infection associated with WTDC during intracranial space-occupying lesion removal than without WTDC in supratentorial craniotomy.

Trends in CSF Leakage Associated with Duraplasty in Infratentorial Procedures over the Last 20 Years: A Systematic Review

Cerebrospinal fluid (CSF) leakage is a common postoperative complication of neurosurgical procedures, with iatrogenic causes accounting for 16% of CSF leakages. This complication increases healthcare costs and patient morbidity. The focus of this review is to analyze the rates of CSF leakage of some of the most commonly used xenogeneic and synthetic dural substitutes following surgeries in the infratentorial region of the brain where surgical repair can be most challenging. A systematic literature search was conducted using studies detailing duraplasty procedures performed with nonautologous grafts in the infratentorial region in PubMed. Studies were identified using the following search terms: "posterior fossa" or "infratentorial" were used in combination with "CSF leak," "CSF leakage," "cerebrospinal fluid leakage," "duraplasty" or "dura graft." The outcome of interest was a measure of the prevalence of CSF leakage rates following posterior fossa neurosurgery. Studies that contributed data to this review were published between 2006 and 2021. The dural graft materials utilized included: bovine collagen, acellular dermis, equine collagen, bovine pericardium, collagen matrix, and expanded polytetrafluoroethylene (ePTFE). The number of subjects in studies on each of these grafts ranged from 6 to 225. CSF leak rates ranged from 0% to 25% with the predominance of studies reporting between 3% and 15%. The studies that utilize bovine collagen, equine collagen, and acellular dermis reported higher CSF leakage rates; whereas studies that utilized ePTFE, bovine pericardium, and collagen matrix reported lower CSF leakage rates. Due to the heterogeneity of methodologies used across these studies, it is difficult to draw a direct correlation between the dural patch products used and CSF leaks. Larger prospective controlled studies that evaluate various products in a head-to-head fashion, using the same methods and animal models, are needed to conclude the relative efficacy of these dural patch products.

Burr hole on polyetheretherketone cranioplasty for the management of chronic subdural hematoma: A case report

Background:

In rare cases, chronic subdural hematoma can be a complication following cranioplasty implantation. Therefore, it can develop spontaneously or after a trauma in the underlying site of a duroplasty and represent, if compression of the brain structures, a life-threatening condition. In case of a patient with cranioplasty in polyetheretherketone (PEEK), performing a burr hole on prosthesis can represent, although unusual, an effective and safe technique for evacuation of the chronic subdural hematoma, avoiding the need to remove the prosthesis itself. Nevertheless, a rare and insidious prosthesis infection can occur, even after years.

Case Description:

A 54-year-old male patient, following severe traumatic brain injury, underwent a right hemispheric decompressive craniectomy associated to acute subdural hematoma evacuation and, subsequently, a PEEK cranioplasty implant with polytetrafluoroethylene (PTFE or Gore-Tex) duroplasty. About 10 years later, he experienced worsening headache with sensory alterations; therefore, he underwent a brain computed tomography scan documenting a right hemispheric chronic subdural hematoma (cSDH), expanding in subsequent radiological examinations. Because of symptoms’ worsening, he underwent cSDH evacuation through a burr hole centered on the parietal region of the PEEK prosthesis, associated with mini-reopening of duroplasty. Two years after the procedure, he went to the emergency department because of the appearance of a serum-purulent material drained from the surgical site. He underwent cranioplasty removal and then started a targeted therapy to treat a triple surgical site infection, often unpredictable and totally accidental.

Conclusion:

Based on the literature evidence, performing a burr hole on a cranial prosthesis in bone-like material such as PEEK represents a surgical procedure never performed before and in our opinion could, in selected cases, guarantee the cSDH evacuation and the treatment of intracranial hypertension, avoiding the cranioplasty removal, although there is a risk of even late surgical site infection.

Outcomes for various dural graft materials after posterior fossa decompression with duraplasty for Chiari malformation type I: a systematic review and meta-analysis

OBJECTIVE

Posterior fossa decompression with duraplasty (PFDD) is often used for Chiari malformation type I (CM-I), but outcomes associated with different dural graft materials are not well characterized. In this meta-analysis, the authors examined complication rates and outcomes after PFDD for CM-I for autografts and four types of nonautologous grafts.

METHODS

A literature search of numerous electronic databases (Ovid Medline, Embase, Scopus, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Database of Abstracts of Reviews of Effects, Health Technology Assessment Database, NHS Economic Evaluation Database, and ClinicalTrials.gov) was performed to identify articles detailing complications for dural graft materials after PFDD. Whenever available, data were also extracted regarding the need for revision surgery, symptom changes after PFDD, and syrinx size changes after PFDD. All searches were compliant with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), Institute of Medicine, Standards for Systematic Reviews, Cochrane Handbook for Systematic Reviews of Interventions, and Peer Review of Electronic Search Strategies guidelines. There were no exclusion criteria based on patient age or presence or absence of syringomyelia.

RESULTS

The current evidence surrounding outcomes for various dural graft materials was found to be of low or very low quality. Twenty-seven studies were included, encompassing 1461 patients. Five types of dural graft materials were included: autograft (n = 404, 27.6%), synthetic (n = 272, 18.6%), bovine pericardium (n = 181, 12.4%), collagen-based (n = 397, 27.2%), and allograft (n = 207, 14.2%). Autograft was associated with a significantly lower rate of pseudomeningocele compared to collagen-based grafts, allografts, and nonautologous grafts in aggregate. Autograft was also associated with the lowest rates of aseptic meningitis, infectious meningitis, and need for revision PFDD, though these associations did not reach statistical significance. No other graft comparisons yielded significant results. Autograft and nonautologous graft materials yielded similar rates of revision surgery and produced similar improvements in postoperative symptoms and syrinx size.

CONCLUSIONS

Autograft was the dural graft material that most frequently had the lowest rate of complications and was associated with significantly lower rates of pseudomeningocele compared to collagen-based graft, allograft, and nonautologous graft materials. Autografts and nonautologous grafts yielded similar outcomes for revision surgery, symptoms, and syrinx size. Large prospective studies comparing different graft materials are needed to accurately and precisely characterize outcomes for individual graft types.

Dural augmentation approaches and complication rates after posterior fossa decompression for Chiari I malformation and syringomyelia: a Park-Reeves Syringomyelia Research Consortium study

OBJECTIVE

Posterior fossa decompression with duraplasty (PFDD) is commonly performed for Chiari I malformation (CM-I) with syringomyelia (SM). However, complication rates associated with various dural graft types are not well established. The objective of this study was to elucidate complication rates within 6 months of surgery among autograft and commonly used nonautologous grafts for pediatric patients who underwent PFDD for CM-I/SM.

METHODS

The Park-Reeves Syringomyelia Research Consortium database was queried for pediatric patients who had undergone PFDD for CM-I with SM. All patients had tonsillar ectopia ≥ 5 mm, syrinx diameter ≥ 3 mm, and ≥ 6 months of postoperative follow-up after PFDD. Complications (e.g., pseudomeningocele, CSF leak, meningitis, and hydrocephalus) and postoperative changes in syrinx size, headaches, and neck pain were compared for autograft versus nonautologous graft.

RESULTS

A total of 781 PFDD cases were analyzed (359 autograft, 422 nonautologous graft). Nonautologous grafts included bovine pericardium (n = 63), bovine collagen (n = 225), synthetic (n = 99), and human cadaveric allograft (n = 35). Autograft (103/359, 28.7%) had a similar overall complication rate compared to nonautologous graft (143/422, 33.9%) (p = 0.12). However, nonautologous graft was associated with significantly higher rates of pseudomeningocele (p = 0.04) and meningitis (p < 0.001). The higher rate of meningitis was influenced particularly by the higher rate of chemical meningitis (p = 0.002) versus infectious meningitis (p = 0.132). Among 4 types of nonautologous grafts, there were differences in complication rates (p = 0.02), including chemical meningitis (p = 0.01) and postoperative nausea/vomiting (p = 0.03). Allograft demonstrated the lowest complication rates overall (14.3%) and yielded significantly fewer complications compared to bovine collagen (p = 0.02) and synthetic (p = 0.003) grafts. Synthetic graft yielded higher complication rates than autograft (p = 0.01). Autograft and nonautologous graft resulted in equal improvements in syrinx size (p < 0.0001). No differences were found for postoperative changes in headaches or neck pain.

CONCLUSIONS

In the largest multicenter cohort to date, complication rates for dural autograft and nonautologous graft are similar after PFDD for CM-I/SM, although nonautologous graft results in higher rates of pseudomeningocele and meningitis. Rates of meningitis differ among nonautologous graft types. Autograft and nonautologous graft are equivalent for reducing syrinx size, headaches, and neck pain.

Applications of materials for dural reconstruction in pre-clinical and clinical studies: Advantages and drawbacks, efficacy, and selections

The dura mater provides a barrier to protect the tissue underneath and cerebrospinal fluid. However, dural defects normally cause cerebrospinal fluid leakage and other complications, such as wound infections, meningitis, etc. Therefore, the reconstruction of dura mater has important clinical significance. Current dural reconstruction materials include: homologous, acellular, natural, synthetic, and composite materials. This review comprehensively summarizes the characteristics and efficacy of these dural substitutes, especially in clinical applications, including the advantages and drawbacks of those from different sources, the host tissue response in pre-clinical studies and clinical practice, and the comparison of these materials across different surgical procedures. Furthermore, the selections of materials for different surgical procedures are highlighted. Finally, the challenges and future perspectives in the development of ideal dural repair materials are discussed.

U-shaped durotomy for midline posterior fossa tumor removal: technical note and evaluation of results

BACKGROUND

The classical dura opening for midline posterior fossa tumors in and around the 4th ventricle and the craniocervical junction is a Y-shaped incision. Several potential problems are associated with this technique. We used a technical variant, the U-shaped durotomy, previously described by Rhoton, offering several advantages. We report on the surgical results of the technique in a consecutive series of posterior fossa cases in children and adolescents.

METHODS

In all midline posterior fossa approaches, a U-shaped dural incision is standard in our institution. All cases were retrospectively analyzed regarding hydrocephalus, placement of EVD or lumbar drain, need for ETV or shunting during follow-up, and frequency of duraplasty, of pseudomeningocele, of primary watertight dural closure, of CSF leakage, and of venous sinus hemorrhage at opening.

RESULTS

Fifty pediatric patients were included. In all easy occipital sinus, control was achieved and no additional dural retraction for tumor exposure required. In 49/50 patients, a primary watertight dura closure without duraplasty was achieved, also in re-do cases with previous U-shaped opening. One patient received a small periostium graft after having had a duraplasty following Y-shaped opening beforehand. No CSF fistula ever occurred and no pseudomeningocele was detected in any follow-up MRI.

CONCLUSION

The U-shaped durotomy for dorsal midline approach to the 4th ventricle and craniocervical junction provides wide exposure to all tumors and allows for primary and watertight dura closure. Compared to published results and complications of classic Y-shaped dural opening, this method of durotomy and closure seems most advantageous.

Autologous cervical fascia duraplasty in 123 children and adults with Chiari malformation type I: surgical technique and complications

OBJECT Techniques for combined extradural and intradural decompression with expansile duraplasty for Chiari malformation type I (CM-I) have been well described, with various allogenic and autologous materials used for duraplasty. However, the approach and surgical technique used for duraplasty in our treatment of CM-I and developed by the senior author in the 1990s has not been described. METHODS A prospective database was initiated in March 2003 to denote the use of cervical fascia for duraplasty and incorporate an ongoing detailed record of complications during the surgical treatment of children and adults with CM-I with and without syringomyelia. A total of 389 surgeries for CM-I were performed on 379 patients from March 2003 to June 2016. A total of 123 posterior procedures were performed on 123 patients in which both a posterior fossa extradural and intradural decompression with duraplasty (extra-intradural) was performed. In this paper the authors describe the surgical technique for harvesting and using cervical fascia for duraplasty in the surgical treatment of CM-I and analyze and discuss complications from a prospective database spanning 2003-2016. RESULTS The authors found that cervical fascia can be harvested in patients of all ages (2-61 years old) without difficulty, and it provides a good substitute for dura in creating an expansile duraplasty in patients with CM-I. Cervical fascia is an elastic-like material with a consistency that allows for a strong watertight closure. Harvesting the cervical fascia graft does not require any further extension of the incision superiorly or inferiorly to obtain the graft. Complications were uncommon in this study of 123 children and adults. The risk of any type of complication (aseptic meningitis, CSF leak, pseudomeningocele, infection, development of hydrocephalus, and need for ventriculoperitoneal shunt) for the 78 patients in the pediatric age group was 0%. The risk of complication in the adult group was 6.7% (1 patient with aseptic meningitis and 2 patients with CSF leak). CONCLUSIONS Autologous cervical fascia is easy to obtain in patients of all ages and provides an effective material for duraplasty in the treatment of CM-I. Complications from the combination of both an extradural and intradural decompression with autologous cervical fascia duraplasty are uncommon.

Closing the dura: dural hitching versus surgicel and tisseel overlay graft in craniocervicaldecompression for Chiari 1 malformation

BACKGROUND

This study compares dural hitching to surgicel and tisseel overlay graft following craniocervical decompression and C1 laminectomy with simple durotomy for Chiari I malformation. Outcome measures were syrinx decompression, headache resolution and complication rates.

METHODS

A retrospective analysis of case notes was conducted. Patients who had undergone craniocervical decompression (CCD) were grouped by method of dural closure. Outcomes compared were rates of syrinx decompression, headache resolution, and post-operative complications. Statistical analysis was conducted using SPSS v20.

RESULTS

We identified 32 adult patients for inclusion in this study. 53.1% (n = 17) had asyrinx, and 78.1% (n = 25) had a pre-operative headache. All were treated with suboccipital craniectomy, C1 laminectomy (with or without C2 laminectomy), and durotomy. The dura was either left open by dural hitching (n = 23) or closed with surgicel and tisseel overlay graft (n = 9). We found a statistically significant association between the method of dural closure and the rate of syrinx resolution. Resolution occurred in 91.7% (n = 11) of the hitching group, compared to 20.0% (n = 1) of the overlay graft group: Χ²(1) = 5.6, p = .018. There were no statistically significant differences between the two groups in the rates of headache resolution or other complications.

CONCLUSIONS

In patients with symptomatic Chiari I malformation and associated syringomyelia, syrinx resolution is more likely if the dura is hitched open rather than closed bysurgicel and tisseel overlay graft after durotomy.

Biocompatible bacterial cellulose membrane in dural defect repair of rat

Duraplasty is necessary in nearly 30% of all neurological surgeries. Different tissues and materials have been evaluated in dura mater repair or as dural substitutes in neurosurgery. The aim was to evaluate the biocompatibility of the bacterial cellulose (BC) membranes, produced from sugarcane molasses, for dural defect repair in rats. Forty adults males Wistar rats divided into two groups: a control (ePTFE) and an experimental (BC). Bilateral frontoparietal craniectomy was performed, and a dural defect was created. The arachnoid underlying defect was disrupted with a narrow hook. The animals were observed for 120 days. There were no cases of infection, cerebrospinal fluid fistulae, delayed hemorrhages, behavior disturbances, seizures and palsies. The BC membrane showed to have suitable biocompatibility properties, was not induced immune reaction, nor chronic inflammatory response and absence of neurotoxicity signals.

Evaluation of Non-Watertight Dural Reconstruction with Collagen Matrix Onlay Graft in Posterior Fossa Surgery

OBJECTIVE

Many surgeons advocate for watertight dural reconstruction after posterior fossa surgery given the significant risk of cerebrospinal fluid (CSF) leak. Little evidence exists for posterior fossa dural reconstruction utilizing monolayer collagen matrix onlay graft in a non-watertight fashion. Our objective was to report the results of using collagen matrix in a non-watertight fashion for posterior fossa dural reconstruction.

METHODS

We conducted a retrospective review of operations performed by the senior author from 2004-2011 identified collagen matrix (DuraGen) use in 84 posterior fossa operations. Wound complications such as CSF leak, infection, pseudomeningocele, and aseptic meningitis were noted. Fisher's exact test was performed to assess risk factor association with specific complications.

RESULTS

Incisional CSF leak rate was 8.3% and non-incisional CSF leak rate was 3.6%. Incidence of aseptic meningitis was 7.1% and all cases resolved with steroids alone. Incidence of palpable and symptomatic pseudomeningocele in follow-up was 10.7% and 3.6% respectively. Postoperative infection rate was 4.8%. Previous surgery was associated with pseudomeningocele development (p<0.05).

CONCLUSION

When primary dural closure after posterior fossa surgery is undesirable or not feasible, non-watertight dural reconstruction with collagen matrix resulted in incisional CSF leak in 8.3%. Incidence of pseudomeningocele, aseptic meningitis, and wound infection were within acceptable range. Data from this study may be used to compare alternative methods of dural reconstruction in posterior fossa surgery.

Two alternative dural sealing techniques in posterior fossa surgery: (Polylactide-co-glycolide) self-adhesive resorbable membrane versus polyethylene glycol hydrogel

BACKGROUND

Post-operative cerebrospinal fluid (CSF) leak in posterior fossa surgery remains a significant source of morbidity. TissuePatchDural (TPD), a novel impermeable adhesive membrane, was used to reinforce dural closure. A comparison with one of the most commonly used dural sealing devices, DuraSeal, has been made.

METHODS

A retrospective, single-center study was conducted on 161 patients who underwent elective posterior fossa surgery. On surgeon's opinion, when a primary watertight closure was not possible, they received TPD or DuraSeal to reinforce dural closure.

RESULTS

Out of 161 patients analyzed, 115 were treated with TPD and 46 with DuraSeal. The post-operative leaks related purely to TPD or DuraSeal failure were recognized in 3 (2.6%) and 5 (10.86%) cases, respectively (P = 0.015). The presence of pre- and post-operative risk factors was associated with an increased incidence of CSF leak in both groups. TPD showed a better control in patients without these risk factors (P = 0.08). The incidence of CSF leak in patients who underwent posterior fossa surgery by craniectomy was statistically lower in TPD group compared to DuraSeal group (3.22% vs 17.8%, respectively; P = 0.008).

CONCLUSIONS

TPD seems to be a safe tool for use as an adjunct to standard dural closure in posterior fossa surgery, particularly in patients without pre- or post-oper ative risk factors, in those who did not develop hydrocephalus, and who underwent craniectomy. The CSF leak rate in TPD group was found to be lower or within the range of the more advanced alternative dural closure strategies, including polyethylene glycol (PEG)-based sealant.

Spinal duraplasty materials and hydrostasis: a biomechanical study

Object

Dural tears are a frequent complication of spinal surgery and contribute to significant morbidity. Occasionally, dural tears cannot be closed primarily and dural patch grafts must be utilized. No data exist on the comparative immediate hydrostatic strength of various patch materials used alone or with a biological adhesive in a spinal dural tear model. Thus, the authors conducted this study to determine the comparative effectiveness of various patch materials used with and without biological adhesive.

Methods

Twenty-four thoracic spines from calves were prepared with laminectomies and spinal cord evacuation, leaving the dura intact. Foley catheters were inflated on either side of a planned dural defect, and baseline hydrostasis was measured using a fluid column at 30, 60, and 90 cm of H2O. A standard dural defect (1 × 2 cm) was created, and 8 patches of each material (human fascia lata, Duragen, and Preclude) were sutured in place using 5-0 Prolene hemo-seal running sutures. Hydrostasis was again tested at the same pressures. Finally, a hydrogel sealant (Duraseal) was placed over the defect and hydrostasis was again tested. Results were analyzed with repeated measures ANOVA.

Results

The leakage rate increased significantly at each pressure tested for all conditions. There was no difference in leakage among the 3 patch materials at any of the pressures or for either condition (with or without sealant). All patch materials allowed significantly greater leakage than the intact condition at all pressures. The use of sealant reduced leakage significantly at the 30 and 60 mm Hg pressures to levels similar to the intact condition. At 90 mm Hg, leakage of the sealed construct was greater than at the intact condition but significantly less than without the use of sealant.

Conclusions

All 3 dural patch materials were of similar hydrostatic strength and allowed greater leakage than at the intact condition. The use of sealant reduced the amount of leakage at all pressures compared with patching alone but allowed more leakage than the intact state at a high hydrostatic pressure (90 mm Hg).

Comparison of dural grafts in Chiari decompression surgery: Review of the literature

BACKGROUND

Decompression of Chiari malformation is a common procedure in both pediatric and adult neurosurgery. Although the necessity for some bony removal is universally accepted, other aspects of Chiari surgery are the subject of debate. The most controversial points include the optimal amount of bony removal, the use of duraplasty (and the type of material), the need for subarachnoid dissection, and the need for tonsillar shrinkage.

MATERIAL AND METHODS

We critically reviewed the literature to elucidate the risks and benefits of different graft types and to clarify optimal treatment options therein. Based on our search results, 108 relevant articles were identified. With specific inclusion and exclusion criteria, we noted three studies that directly compared two tlpes of dural substitutes in Chiari malformation surgery.

RESULTS

Our review did not support the superiority of either autologous or nonautologous grafts when duraplasty is employed. Our institutional experience, however, dictates that when the pericranium is available and of good quality, it should be utilized for duraplasty. It is non-immunogenic, inexpensive, and capable of creating a watertight closure with the dura.

CONCLUSIONS

Discrepancies between the three comparative studies analyzed are likely attributable to increases in pericranial quality and thickness with maturity. Future randomized studies with large numbers and the power to resolve differences in the relatively low rates of complications in Chiari surgery are warranted.

Biomaterials in skull base surgery

Reconstruction materials and techniques for the base of the skull have undergone rapid developments and differentiation in recent years. While mostly autotransplants, collagens or resorbable alloplastic materials are preferred for duraplasties, pronounced organ-specific differences can be observed in the reconstruction of hard tissues. The use of polymethylmethacryl bone cement, once wide-spread, has decreased greatly due to the release of toxic monomers. Bony autotransplants are still used primarily for smaller skull-base defects, intraoperatively formable titanium nets may be also used for larger fronto- or laterobasal reconstructions of bony defects. Defects in visible areas are increasingly closed with preformed titanium or ceramic implants, which are planned and fitted to the individual patient using preoperative CT imaging. At the skull base, this applies especially to reconstructions of the frontal sinus. For extensive reconstructions of the orbita, titanium nets and non-resorbable plastics have proven valuable; in closing smaller defects especially of the orbital floor, resorbable implants based on Polyglactin 901 are also used.

Dura mater regeneration with a novel synthetic, bilayered nanofibrous dural substitute: an experimental study

Aim: To create a synthetic nanofibrous dural substitute that overcomes the limitations of current devices by enhancing dural healing via biomimetic nanoscale architecture and supporting both onlaid and sutured implantation. Materials & methods: A custom electrospinning process was used to create a bilayer dural substitute having aligned nanofibers on one side and random nanofibers on the other. Nanoscale architecture was verified using microscopy and macroscale mechanical properties were investigated using tensile testing. Biological response to this device was investigated both in vitro and in a canine duraplasty model. Results & conclusion: Bilayer nanofiber alignment yields a graft having anisotropic mechanical properties with significantly higher strength and suturability than a commercially available collagen matrix. When implanted, the nanofibrous graft prevents leaks and brain tissue adhesions, and encourages dura mater regrowth, performing comparably to the collagen matrix. Both in vitro fibroblast orientation and in vivo dural healing are enhanced by the aligned nanofibers.

Dural tears in spine surgery

Dural tears are among the most commonly seen complications in spine surgery. Most studies in the literature indicate that long-term outcomes are not negatively affected, provided that the tears are diagnosed early and managed appropriately. Direct suture repair remains the preferred method for the management of durotomy caused by or found during surgery. However, recent literature reports encouraging results with sutureless repair. Understanding dural anatomy, dural healing, and cerebrospinal fluid dynamics is helpful in choosing among the available management options for dural tear.

Dural augmentation: part I-evaluation of collagen matrix allografts for dural defect after craniotomy

OBJECTIVE

Primary closure of the dura remains difficult in many neurosurgical cases. One option for dural grafting is the collagen sponge, which is available in multiple forms, namely, monolayer collagen and bilayer collagen. Our primary goal was to assess differences in the incidence of postoperative cerebrospinal fluid (CSF) leak, including fistula and pseudomeningocele, and postoperative infection between monolayer collagen and bilayer collagen grafts.

METHODS

A single-center retrospective analysis of 475 consecutive neurosurgical procedures was performed. Primary endpoints were CSF leak and infection, adjusting for the impact of additional nonautologous materials. Multivariate regression analysis was used to identify predictors of postoperative CSF leak and infection.

RESULTS

The overall frequency of postoperative CSF leak was 6.7%. There was no significant difference in the incidence of CSF leak based on the type of collagen sponge (monolayer versus bilayer) used (5.5% versus 7.5%, respectively; P = 0.38). The overall frequency of postoperative infection was 4.2%. There was no significant difference in the incidence of infection between groups (4.9% versus 3.8%; P = 0.54). Bilayer sponges were associated with a significantly lower incidence of CSF leak than monolayer sponges (odds ratio, 0.09; 95% confidence interval, 0.01-0.73).

CONCLUSION

Bilayer collagen sponges are associated with a reduction in postoperative CSF leak, notably in posterior fossa surgery. The need for additional non-native materials is predictive of postoperative CSF leak, along with location and type of procedure. Intrinsic patient characteristics (e.g., age, diabetes, smoking) do not seem to affect the efficacy of collagen sponge dural grafts.

A pilot study of fat allograft transplantation in immunocompetent rabbits for potential neurosurgical applications

OBJECT

The authors investigated the feasibility of using fat allografts (chemically treated to reduce the host immune response) for neurosurgical applications.

METHODS

Subcutaneous fat specimens collected from New Zealand White rabbits were treated with DNAse I and sodium deoxycholate to reduce immunogenicity before subcutaneous, midscapular implantation in immunocompetent recipient rabbits. Allograft incorporation and the host-allograft response were examined at 1, 6, and 11 weeks by histopathological analysis. Control specimens of autograft and untreated fat allograft implants were examined for comparison.

RESULTS

The host immune response was markedly reduced in the region around the chemically treated fat allografts when compared with untreated allografts, and was similar to the tolerant host response to autografts.

CONCLUSIONS

Based on their results, the authors suggest that fat allografts processed for reduced immunogenicity may be a convenient, viable alternative for neurosurgical applications.

Postoperative complications associated with dural substitutes in suboccipital craniotomies

OBJECTIVE

Dural replacements are used in cranial surgery when primary closure of native dura is not possible. The goal is to recreate a watertight barrier to prevent cerebrospinal fluid leakage with few associated complications. We reviewed a single-institution experience with a variety of dural substitutes in posterior fossa neurosurgery, for which higher complication rates are well described.

METHODS

Patients were screened for suboccipital posterior fossa neurosurgery between November 2005 and April 2007. Surgical logs were reviewed for diagnosis, procedure, and use of dural replacement. Clinical courses were reviewed for hydrodynamic complications, including delayed hydrocephalus, clinically significant pseudomeningocele, aseptic meningitis, and persistent cerebrospinal leakage.

RESULTS

One hundred twenty-eight patients were included, and a dural replacement was used in 106. Overall, the complication rate was 21.9% (28 patients). Complications were seen for acellular human dermis in 33.3%, for collagen matrix in the original formulation in 18.2%, for the reformulation in 16.9%, for the suturable formulation in 50%, for nonautologous materials in 24%, and for no dural replacement in 16.7%. Univariate and multivariate analysis demonstrated that hydrodynamic complications were associated with use of the suturable collagen matrix (odds ratio, 10.8; 95% confidence interval, 2.5-46.1; P = 0.0014) and trended with use of acellular human dermis (odds ratio, 4.6; 95% confidence interval, 0.9-23.1; P = 0.06).

CONCLUSION

The increased risk of hydrodynamic complications associated with suboccipital neurosurgery is modified by choice of dural replacement. Similar complication rates were seen for most materials with a variety of primary abnormalities, with the exception of suturable bovine collagen matrix, with hydrodynamic complications in 50% of patients.

Suboccipital decompression for Chiari I malformation: outcome comparison of duraplasty with expanded polytetrafluoroethylene dural substitute versus pericranial autograft

OBJECTIVE

Treatment failure for Chiari decompression is frequently associated with scarring, intradural adhesions, and recurrent loss of hindbrain space. While autograft has been our standard for hindbrain duraplasty, we investigated whether introducing anti-adhesive synthetic GORE PRECLUDE MVP Dura Substitute (expanded polytetrafluoroethylene [ePTFE] graft) was associated with improved patient outcomes.

MATERIALS AND METHODS

We retrospectively reviewed records of patients undergoing first-time suboccipital decompression/duraplasty for Chiari-I malformation utilizing ePTFE graft or pericranial autograft. Magnetic resonance imaging (MRI) at last follow-up was assessed for: (1) recurrent loss of dorsal hindbrain cerebrospinal fluid (CSF) space/CSF flow(cine-MR) at duraplasty site, (2) pseudomeningocele, or (3) syringomyelia improvement. Symptom recurrence warranting revision surgery was compared between cohorts.

RESULTS

Sixty-seven patients (age 11 +/- 5 years) underwent duraplasty with pericranial autograft (n = 40) or ePTFE graft (n = 27). Perioperative morbidity did not differ between cohorts. No patients receiving ePTFE graft experienced incisional CSF leak, surgical site infection, or symptomatic pseudomeningocele. At median 8 months postoperatively, all (100%) patients with ePTFE graft maintained physiological CSF flow/decompressed hindbrain CSF space on cine-MRI versus 32 (79%) patients receiving pericranial autograft (p < 0.05). Radiographic syrinx improvement occurred in 80% of patients with ePTFE graft and 52% of patients with pericranial autograft (median time to improvement: 5 vs 12 months, respectively, p < 0.05). At median 16 months postoperatively, four (10%) patients with pericranial autograft required revision decompression versus 0 (0%) patients with ePTFE graft (p = 0.090).

CONCLUSION

Duraplasty utilizing ePTFE graft was associated with improved maintenance of hindbrain space, accelerated syringomyelia improvement, and a trend toward decreased treatment failure versus pericranial autograft. Future studies of long-term outcome are warranted to confirm observed effects. Synthetic ePTFE graft is a safe alternative for duraplasty in the setting of Chiari malformation.

Dural bridge sutures to prevent sinking of dural substitutes: technical note

INTRODUCTION

Following Simpson Grade 1 excision of large convexity meningioma there is often a need for synthetic dural substitutes.

DISCUSSION

One problem with some of these grafts is that they lack tensile strength when wet and therefore sink into the cavity left following removal of the meningioma.

CONCLUSION

A simple method to prevent 'sinking' or sagging of such synthetic dural grafts is described and illustrated.

[Surgical treatment of Arnold-Chiari malformation type I in an adult patient]

BACKGROUND

Herniation of the cerebellar tonsils through the foramen magnum into the cervical spinal canal with obliteration of the cerebellomedullary cistern is the primary feature of Arnold-Chiari type I malformation (ACM I). It is considered to be congenital malformation, although there have been reported cases of an acquired form.

CASE REPORT

We presented a female patient, 45-year old, with ACM I without syringomyelia as a rare and unusual clinical image, as well as the effect of decompressive surgery in the treatment of this malformation. The patient was admitted to the Department of Neurosurgery with clinical signs of truncal ataxia worsening during the last six years. Moderate quadriparesis with predominant lower extremity involvement and the signs of the cranial nerves damages occured during the last seven months before admission, with progressive clinical course up to the date of admission. Neurosurgical treatment that included suboccipital medial craniectomy with resection of posterior arch C1 vertebrae and C2 laminectomy resulted in a significant clinical improvement and a much better quality of life.

CONCLUSION

Posterior craniovertebral decompression with microsurgical reduction of the cerebellar tonsils and placement of an artificial dural graft is a treatment of choice in severe forms of ACM I without syringomyelia.

Development of watertight and bioabsorbable synthetic dural substitutes

We have developed novel watertight and bioabsorbable synthetic dural substitutes. The substitutes were designed such that they had a three-layered structure, and each layer comprised a bioabsorbable copolymer prepared from L-lactide, glycolide, and epsilon-caprolactone. Various copolymers were synthesized, and appropriate compositions were selected for preparing the substitutes based on the results of leakage tests. Experimental substitutes that prevented the leakage of saline through the suture lines between the substitutes and dura mater were prepared. An in vitro study was performed in which the substitutes were sutured to porcine dura mater, and the amount of saline leakage was measured. It was demonstrated that leakage through the suture line could be completely suppressed by using the substitutes we developed along with favorable suturing techniques.