Bone Sandwich Closure Technique for Posterior Fossa Craniectomy

摘要

Background?Surgery of posterior fossa including cerebellopontine (CP) angle involves either craniectomy or craniotomy. While there has been precedence of craniotomy in recent practice, the preferred access in resource-strapped centers still remains been craniectomy. Although the latter offers an excellent exposure, it is believed to carry increased risk of postoperative pseudomeningocoele and cerebrospinal fluid (CSF) leak compared with craniotomy.Methods?We have suggested a technique by which after standard craniectomy for the posterior fossa surgeries the bony defect is covered by Gelfoam bone sandwich (GBS) technique. We studied this technique over a period of 25.6 years in 1,028 patients.Results and Conclusion?We analyze the risk of pseudomeningocoele and CSF leak in our patients using GBS technique and reviewed literature to compare our outcomes with standard craniotomy and craniectomy procedures. Keywords: posterior fossa, bone sandwich, CSF leak, pseudomeningocoele, craniectomyIntroductionPseudomeningocoele and cerebrospinal fluid (CSF) leak remain the most common complication encountered in posterior fossa surgeries, whether cerebellopontine (CP) angle, unilateral, or midline suboccipital approaches.~(1)~(2)Among all the factors which these complications have most commonly been associated with, one is the kind of bony exposure that has been opted for craniotomy or craniectomy. Given the small surgical area, traditionally, craniectomy was preferred for the easy and wide exposure with less risk of sinus and dural tear besides other factors.~(1)However, craniectomy has been associated with increased risk of pseudomeningocoele and CSF leak.~(1)~(3)~(4)~(5)~(6)~(7)~(8)Cranioplasty or craniotomy with bone flap replacement would then seemingly be the preferred option to prevent the above complications and is evidenced by precedence of the same in recent practice; yet craniectomy is still practiced in resource-strapped centers. We share our experience of a novel and simple alternative to standard postcraniectomy bony defect closure techniques.AimThe main purpose of this article is to provide an alternative and novel technique for posterior fossa craniectomy defect closure with bone and Gelfoam sandwich to avoid CSF leak/pseudomeningocoele.Materials and MethodsThe study was conducted on patients who presented with posterior fossa pathology and were operated on. These patients may on occasion have hydrocephalous at time of presentation. We do not routinely place shunts for patients having preoperative hydrocephalus unless patient has clinically significant hydrocephalus and is symptomatic.Inclusion CriteriaAll patients who underwent a posterior fossa surgery, including CP angle and other posterior fossa tumors, surgery for auditory brain stem implant and decompressive craniectomy, between January 1991 and June 2016 in our department, were included in our study. Patients were followed up through regular outpatient department visits, once weekly for first month and once a month thereafter for 6 months. This was managed by regular telephonic and/or postal communication. Those with a minimum follow-up period of 6 months were included in the study.Exclusion CriteriaPatients who underwent recraniotomy were excluded from the study since presence of postsurgical scars makes the dural closure difficult and was considered to be a potential confounding factor. Those with a follow-up period of less than 6 months were also excluded.Surgical TechniqueIn all our patients, we routinely place a burr hole (“safety burr hole”) at Frazier's point to enable tapping of ventricles should the need be in the perioperative and postoperative period.Following this, standard posterior fossa craniectomy (retromastoid or mid-line suboccipital) was performed by placing three to four burr holes with standard perforators, and drills equipped with protective guard and remaining bone was removed with rongeurs. The bone bits and bone dust were saved and were placed in saline till the end of the procedure. At the end of the procedure, type of dural closure was recorded (watertight dural closure or watertight duraplasty or overlay graft [overlay duraplasty] with autologous fascia, fat). Valsalva maneuver was used to check and classify the dural closure as watertight or not.Gelfoam Bone Sandwich TechniqueThe technique of preparation and placement of bone sandwich is outlined as below and depicted sequentially inFig. 1: Open in a separate windowFig. 1 Technique of bone sandwich placement. Craniectomy is performed (A); A piece of Gelfoam cut half way is taken (B) into which bone dust and bits are placed (C,D) which is then placed over craniectomy defect (E,F).