Impact of Dual-Layer Duraplasty During Hemicraniectomy on Morbidity and Operative Metrics of Cranioplasty: A Retrospective Case-Control Study Comparing a Single- Layer with a Dual-Layer Technique James M. Wright 1,4 , Alankrita Raghavan 4 , Christina Huang Wright 1,4 , Andrea Alonso 4 , Hasina Momotaz 2,4 , Jennifer Sweet 1,4 , Martha Sajatovic 2-4 , Warren Selman 1,4 - BACKGROUND: Dural substitutes used during hemi- craniectomy provide a barrier and dissection plane during subsequent cranioplasty. A recent review by our group showed that use of dural substitutes in hemicraniectomy is associated with reduction in estimated blood loss (EBL) and operative time (OT). In our experience, the use of a dual-layer technique facilitates a dissection plane with minimal adhesions. We hypothesized that use of this dual- layer technique would show decreased OT and EBL in patients undergoing cranioplasty. - METHODS: We conducted a retrospective case-control study comparing use of single-layer versus dual-layer duraplasty on cranioplasty operative outcomes. Data on dual-layer cases were collected from patients who un- derwent cranioplasty from 2013 to 2017. These data were matched to controls from 2008 to 2012. Patients were identified by query of a neurosurgical database of all procedures performed at our institution. Patients were included if they had complete surgical records for cra- nioplasty. Cases and controls were compared with a Stu- dent t test, c 2 test, or Fisher exact test. - RESULTS: A total of 78 controls and 45 cases met inclusion criteria. All baseline characteristics between cohorts were similar except for surgical indication. Mean OT (102.97 mi- nutes vs. 102.18 minutes) and mean EBL were not signifi- cantly different (204.66 mL vs. 190 mL) between cohorts. - CONCLUSIONS: In this study, we did not detect any significant difference between EBL and OT with use of single-layer versus dual-layer duraplasty. Mean EBL was slightly higher in the controls compared with cases but this difference was not statistically or clinically significant. This concept would benefit from a prospective randomized study. INTRODUCTION D ecompressive craniectomy is a common neurosurgical procedure used in the treatment of medically refractory increases in intracranial pressure. This situation commonly results from traumatic brain injury, mass effect asso- ciated with ischemic and hemorrhagic stroke, or diffuse cerebral edema. 1 Craniectomy entails the removal of a portion of the calvarium and opening of the dura mater to allow for swelling of intracranial contents. This procedure has been shown to significantly decrease measures of intracranial pressure, intensive care unit length of stay, and mortality. 2 A subsequent skull reconstruction procedure, termed cranioplasty, is completed weeks to months later, after cerebral swelling has resolved and the patient has recovered from the initial hospitalization. The optimal timing of cranioplasty remains a topic of debate and is not the focus of this work. 3-5 After decompressive craniectomy, adhesions and inflamma- tory tissue form and can increase the technical difficulty of cranioplasty. These adhesions may increase the risk associated with this procedure. The literature supports that the presence of adhesions leads to higher rates of perioperative morbidity and may predispose patients to an increased risk of infection, Key words - Blood loss - Cranioplasty - Duraplasty - Hemicraniectomy - Operative time - Reoperation Abbreviations and Acronyms EBL: Estimated blood loss ePTFE: Expanded polytetrafluoroethylene OT : Operative time SD: Standard deviation From the 1 Department of Neurological Surgery, 2 Neurological and Behavioral Outcomes Center, and 3 Department of Neurology and Psychiatry, University Hospitals Cleveland Medical Center, Cleveland; 4 Case Western Reserve University School of Medicine, Cleveland, Ohio, USA To whom correspondence should be addressed: James M. Wright, M.D. [E-mail: James.Wright@UHHospitals.org] Citation: World Neurosurg. (2019). https://doi.org/10.1016/j.wneu.2019.01.276 Journal homepage: www.journals.elsevier.com/world-neurosurgery Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2019 Elsevier Inc. All rights reserved. WORLD NEUROSURGERY -: e1-e7, - 2019 www.journals.elsevier.com/world-neurosurgery e1 Original Article