- Department of Neurosurgery, University of Illinois at Chicago, Chicago, IL, USA
Konstantin V. Slavin
Department of Neurosurgery, University of Illinois at Chicago, Chicago, IL, USA
DOI:10.4103/2152-7806.107904Copyright: © 2013 Slavin KV This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
How to cite this article: Williams LE, Vannemreddy PS, Watson KS, Slavin KV. The need in dural graft suturing in Chiari I malformation decompression: A prospective, single-blind, randomized trial comparing sutured and sutureless duraplasty materials. Surg Neurol Int 27-Feb-2013;4:26
How to cite this URL: Williams LE, Vannemreddy PS, Watson KS, Slavin KV. The need in dural graft suturing in Chiari I malformation decompression: A prospective, single-blind, randomized trial comparing sutured and sutureless duraplasty materials. Surg Neurol Int 27-Feb-2013;4:26. Available from: http://sni.wpengine.com/surgicalint_articles/the-need-in-dural-graft-suturing-in-chiari-i-malformation-decompression-a-prospective-single-blind-randomized-trial-comparing-sutured-and-sutureless-duraplasty-materials/
Background:This study compared the use of two commonly utilized dural closure techniques used in augmentation duraplasty for Chiari malformation I (CM I) and evaluated their efficacy and outcome in terms of quality of life assessments.
Methods:This prospective randomized study compared sutureless (DuraGen) and suturable (Dura-Guard) techniques in CM I decompression. Clinical parameters, cost analysis, and SF-36 Quality of Life Questionnaire (QLQ) were utilized to assess outcome.
Results:Thirty-four patients were enrolled. Average age was 38.7 ± 12.2 years (mean ± SD (Standard Deviation)) and 82% of patients were female. Sixteen patients received DuraGen and 18 Dura-Guard. Age and gender were similar among groups. Postoperative complications did not differ between groups. Operative cost and time were less for DuraGen, whereas hospital stay was less with Dura-Guard, neither was statistically significant. Average QLQ scores at months 1, 2, and 3 improved in both groups. Dura-Guard patients showed greater improvement in quality of life at month 2 (P P P P
Conclusion:Both techniques are effective in reaching the goals of decompressive surgery for CM I and did not differ in quality of life at final survey. All patients showed significant improvement in physical function, physical health, and outcome following surgery. With all variables being equal the choice of duraplasty material may be based upon surgeon's preference.
Keywords: Chiari malformation, dural substitutes, duraplasty, outcome, posterior fossa
Dura mater may be damaged as a result of trauma, surgery, or tumor involvement and its reconstruction traditionally involved use of harvested autologous membranes like the pericranium, fascia lata, or temporalis fascia. These native collagen grafts are immunologically accepted without rejection and/or reaction and get reconstituted with host cells and supporting vasculature. Subsequently they are incorporated into host tissue. This biological response to the native tissue remains an ideal to which any other dural substitutes can be compared[
Dura-Guard, derived from processed bovine pericardium, is a strong membranous implant that is sutured to the surrounding dura. DuraGen, in contrast, is a collagen matrix derived from bovine Achilles tendon and is implanted, without suture, as an on-lay graft to cover dural defects. To emphasize, DuraGen does not require suturing to the surrounding dura.[
In 1891, Hans Chiari first document 3 rhombencephalic congenital defects that are now classified as Chiari malformation Types I, II, and III.[
This study focuses on posterior fossa decompression for the treatment of CM I and the possible benefits of sutured vs. sutureless duraplasty in a surgery requiring an opening of the dura mater. The efficacy of DuraGen and Dura-Guard as dural substitutes in cranial and spinal surgery has been previously reported. The literature is distinctly sparse, however, on outcome and cost analysis data following posterior cranial fossa augmentation duraplasty utilizing the two dural substitutes.[
Institutional review board and human subject protection
This research was conducted with approval and under the guidance of the University of Illinois at Chicago's (UIC) Institutional Review Board. The study was listed at
All patients scheduled for CM I decompression surgery in the Department of Neurosurgery at our university, who met inclusion criteria and were approved for participation by the treating physician, were approached for enrollment and those who agreed to participate signed written informed consent.
Study subject inclusion and exclusion
Study subjects were included based upon the following criteria: >18 years of age; clinical diagnosis of CM I; radiographic evidence of downward tonsillar herniation by an official independent radiology report; and written informed consent.
The exclusion criteria included the following: Presence of hydrocephalus or previous cerebrospinal fluid (CSF) diversion procedure, such as shunt; prior operation on the posterior cranial fossa; inability to understand the informed consent or unwillingness to participate in the study; inability, at time of consent, to return for follow up evaluations 3 months after the surgery; evidence of spinal dysraphism; allergy or history of allergic reaction to DuraGen, Dura-Guard, or their components; or pregnancy.
Subject randomization and blinding procedures
Subjects were randomized to one of the two techniques, sutureless duraplasty with DuraGen or sutured with Dura-Guard, immediately prior to Chiari decompression surgery. Randomization was 1:1 to DuraGen or Dura-Guard and the subjects were blinded to the results of randomization.
Decompression surgery procedures
Treatment within the study protocol did not deviate from standard practice. Following suboccipital craniectomy and C1 posterior arch excision, dura was opened along with arachnoid membrane to facilitate CSF flow and all visible arachnoid adhesions were released. After an adequate intradural decompression the duraplasty was performed with either DuraGen or Dura-Guard depending on randomization. Dura-Guard patches were sutured to the native dura in a watertight fashion using 4-0 Nurolon running nonlocking suture, whereas DuraGen was placed over the dural opening without any sutures or glue. In most cases, DuraGen was tucked under the native dura. After discharge from the hospital, the patients were seen in the outpatient neurosurgical clinic for suture removal and follow up examinations for the duration of study.
Operative parameters and study follow up procedures
Patients were followed for 3 months postoperatively with the SF-36 Quality of Life Questionnaires (QLQ) and for specific complication indicators. Complication parameters evaluated were: Presence of pseudomeningocele based on clinical examination and follow up magnetic resonance imaging (MRI); postoperative meningitis (infectious and aseptic), evaluated by clinical symptoms and/or lumbar puncture; development of CSF leak; and postoperative wound infection. We also analyzed duration of surgery (minutes); blood loss (milliliters); length of postoperative hospital stay (days); readmissions and emergency room (ER) visits within 30 days following surgery; and other postoperative complications not included above.
Total charges were calculated as actual hospital charges incurred from surgery to discharge. Operating cost was calculated as actual hospital charges specified as operating room cost, anesthesia cost and recovery room cost. Each was assessed individually and additively (total operating time cost) for statistical significance. The complication management cost was determined by the cost of treatment of complications occurring after the initial hospital treatment. Among others, it included cost of all readmissions, ER visits and outpatient visits related to any complication of surgery.
SF-36 quality of life grading and evaluation
Symptomatic improvement vs. stabilization vs. worsening was measured by the SF-36 health outcomes survey (Quality Metric, Lincoln, RI, USA) at months 1, 2, and 3 postoperatively. Outcome was evaluated by subject reported response to the month 1, SF-36 questionnaire question #2: “Compared to one year ago, how would you rate your health in general now?” Subjects were also evaluated for outcome via this criterion at their last postoperative, or month 3, questionnaire evaluation. The SF-36 quality of life questionnaire scores resulted in five specific scoring categories.
Scores range from 1 to 100 (1 = very poor and 100 = excellent), and these categories are: physical function, physical role, pain, general health, vitality, social function, emotional role, and mental health. The questionnaire also gives a total physical health and mental health score that ranges from 1 to 100. The total QLQ score was determined by adding the total physical health and mental health scores together (score 1-200). Scores for each specific category, total physical, total mental, and total QLQ score were individually assessed at the three time points (months 1, 2, and 3) and were averaged across all time points for an overall assessment of each parameter.
Follow up evaluation was conducted for objective evaluation of outcome and marked as better, same or worse. All patients were examined in person and the questionnaires were filled at the time of follow up visit.
The study data was compared relative to randomization to DuraGen or Dura-Guard and conclusions were drawn based on all previously described variables. Study data was also compared at different time points to determine overall efficacy of posterior fossa decompression for CM I.
All statistics were performed with the use of the Statistical Analysis Software (SAS) Version 9.2 (Cary, NC, USA) and Prism 4 (La Jolla, CA, USA) for Windows, Version 4.00, released April 2003. Statistical significance was assumed significant at a P value of <0.05. All parameters were evaluated, relative to each material used, with a Student t-test or with the Mann–Whitney test.
The study was conducted over the period of 2002-2011. Out of more than a 150 CM patients undergoing surgery in our institution, 34 patients met all inclusion and exclusion criteria, agreed to written informed consent, and participated in the study. Sixteen patients were randomized to DuraGen and 18 were randomized to Dura-Guard.
No statistical difference was found between the two treatment groups, DuraGen or Dura-Guard, based upon age, average age was 38.7 ± 12.2 years (mean ± SD), or duration of preoperative symptoms, average duration was 37 ± 49 days (mean ± SD). There was no significant difference in gender between the two groups; overall, there were 28 females and 6 males. No statistical difference was found between the two treatment groups on the basis of insurance status, smoking, drug, or alcohol use.
No significant difference was found between the two treatment groups for operative time, hospital stay, and blood loss during surgery [
Although not specifically measured, the size of craniectomy and extent of C1 posterior arch resection did not differ between the groups as we routinely perform 2.5-3 cm-wide semicircular craniectomy and 2-2.5 cm-wide resection of C1 arch.
No significant difference was found between the two treatment groups for postoperative complication parameters: Presence of complications, pseudomeningocele, meningitis, CSF leak, other complications, readmissions, or ER visits [
There was a clear difference in incidence of some complications: Meningitis occurred in 1/16 patients with DuraGen group and 2/18 in Dura-Guard, CSF leak happened in 2/16 of DuraGen patients and 0/18 of Dura-Guard, and radiographic pseudomeningocele in 6/16 of DuraGen and 6/18 Dura-Guard patients. None of these differences reached statistical significance [
No significant difference was found between the two treatment groups for total charges, hospital stay cost, postdischarge treatment cost, or operative cost [
SF-36 QLQ parameters
No significant difference was found between the two treatment groups, averaged across all time points, for specific QLQ survey parameters: Physical function, physical role, pain, general health, vitality, social function, emotional role, and mental health. Nor was there a significant difference between the two study groups for total physical health, total mental health, or total QLQ score [
Evaluation of efficacy for all study patients showed a significant improvement in total physical health at month 3 (36.99 ± 0.36, mean ± SEM) compared with month 1 (29.21 ± 0.26, mean ± SEM) (P = 0.0043) and at month 2 (34.32 ± 0.29, mean ± SEM) compared with month 1 [P = 0.027, Figure
(a) For all patients, a comparison of all specific QLQ parameters at months 1 and 3 postoperatively (b) For all patients, a comparison of physical function and physical health at questionnaire time points (month 1, 2, and 3). Bar graph representing mean ± SEM, * indicates significance P< 0.05, and ** indicates significance P< 0.005
Furthermore, study subjects did not show a significant increase in total QLQ score (1-200), which is the result of adding together total mental health (1–100) and total physical health (1–100) from months 1 to 3 postoperatively [
(a) For all patients, Total QLQ score (1-200) results from the addition of the total physical and mental score at months 1 and 3 postoperatively (b) For all patients, the outcome rating at 1 and 3 months postoperatively. Outcome rating corresponds to patient-reported response to the question “Compared to one year ago how would you rate your health in general now?” A score of-2 indicates an answer of “Much worse than one year ago.” A score of 0 indicates an answer of “The same as one year ago.” A score of 2 indicates an answer of “Much better than one year ago.” * indicates significance of < 0.05
No significant difference was observed between groups, DuraGen or Dura-Guard, for outcome evaluations at months 1 and 3. All patients, however, showed a significant improvement in their outcome response “Compared to one year ago how would you rate your health in general now?” between months 1 and 3 (P = 0.0112) [
The purpose of this study was to determine whether the process of suturing the dural collagen-based graft during posterior fossa decompression in patients with CM I alters the outcome and/or reduces incidence of complications. We also evaluated whether the type of duraplasty, sutureless with DuraGen, or sutured with Dura-Guard, translates into additional cost both during surgery and postoperatively. Furthermore, study data was compared at different time points throughout the clinical course to determine overall efficacy of surgery.
The two study groups, DuraGen and Dura-Guard, exhibited comparable demographic parameters indicating that differences in clinical course could be correlated with randomization to either duraplasty material. Similarly, it has been previously reported that intrinsic patient characteristics (e.g., age, alcohol, drug abuse, duration of symptoms, and smoking) do not affect the efficacy of collagen dural grafts.[
We did not find any significant difference in clinical course (operative time, hospital stay, and blood loss during surgery) between sutureless (DuraGen) and suturable (Dura-Guard) [
Hospital stay for Dura-Guard was on average less but not significantly different from DuraGen (P = 0.06). In this case, the lack of a statistically significant difference is not surprising as the postoperative treatment was essentially identical between the two groups. For postoperative parameters, Dura-Guard and DuraGen showed somewhat larger than expected incidence of complications, infections, CSF leaks, pseudomeningocele formation, ER visits, and readmissions. Zerris, et al. studied somewhat similar parameters in animal experiments comparing Dura-Guard with DuraGen and none of the animals developed CSF leak, seizures, hemorrhage, hydrocephalus, foreign body reaction, or infection.[
The cost analysis portion of our study indicated that there was no significant difference in cost for DuraGen compared with Dura-Guard duraplasty [
Dura-Guard patients compared with DuraGen showed more improvement in quality of life at month 2. However, scores did not significantly differ between groups at the final follow up [
Nevertheless, both DuraGen and Dura-Guard patients had comparable results in the QLQ categories of total mental and total physical health [
Interestingly, patients did not show a significant difference between months 1 and 3 for specific QLQ survey parameters physical role, pain, general health, vitality, social function, emotional role, or mental health [
It should be noted that one of the limitations of this study was the small sample size and long period of accrual. The National Institutes of Health estimates the prevalence of CM I to be 1 in 1000 individuals and this may or may not include patients that are asymptomatic.[
Multiple concerns that arise when using autologous collagen implants (inconsistent availability, surgical morbidity at the donor site, and the need for enlargement of original incision or creation of additional incisions) can be addressed by the processed bovine collagen grafts. Both sutureless and suturable xenogeneic dural substitutes are effective in reaching the goals of posterior fossa decompressive surgery for CM I. Interestingly, with the clinical course of both treatments being statistically similar, surgical time is the only variable that affects the surgeon and shorter surgical time is always preferred by any operating team. Furthermore, shorter surgical time translates into shorter duration of anesthesia and, at least theoretically, should improve outcome and lower the chances of complications. Based on our findings, we conclude that posterior fossa decompression with either duraplasty technique results in an improvement in patients compared with one year prior to surgery, as seen with patient's response to the outcome question, and emphasizes the physical deficits that can be alleviated with treatment. Furthermore, with similar clinical outcomes and comparable costs there is no benefit to the patient for surgeons to take additional effort suturing the dural graft. Ultimately, the choice of duraplasty material may be based upon the surgeon's preference.
The authors of the paper would like to express their gratitude to MBA, and the University of Illinois at Chicago Department of Neurosurgery's faculty, residents, and staff for their assistance in the data collection, preparation, and analysis.
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