Postoperative CSF leak after translabyrinthine surgery

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1 J Neurosurg 119: , 2013 AANS, 2013 Prevention of postoperative cerebrospinal fluid leaks with multilayered reconstruction using titanium mesh hydroxyapatite cement cranioplasty after translabyrinthine resection of acoustic neuroma Technical note Sunil Manjila, M.D., 1 Mark Weidenbecher, M.D., 2 Maroun T. Semaan, M.D., 2 Cliff A. Megerian, M.D., 1,2 and Nicholas C. Bambakidis, M.D. 1 Departments of 1 Neurological Surgery and 2 Otolaryngology, University Hospitals Case Medical Center, Cleveland, Ohio Object. Several prophylactic surgical methods have been tried to prevent CSF leakage after translabyrinthine resection of acoustic neuroma (TLAN). The authors report an improvised technique for multilayer watertight closure using titanium mesh hydroxyapatite cement (HAC) cranioplasty in addition to dural substitute and abdominal fat graft after TLAN. Methods. The study was limited to 42 patients who underwent TLAN at University Hospitals Case Medical Center using this new technique from 2006 to Systematic closure of the surgical wound in layers using temporalis fascia, dural substitute, dural sealant, adipose graft, titanium mesh, and then HAC was performed in each case. Temporalis muscle and eustachian tube obliteration were not used. The main variables studied were patient age, tumor size, tumor location, cosmetic outcome, length of hospitalization, and the incidence of CSF leak, pseudomeningocele, and infection. Results. Excellent cosmetic outcome was achieved in all patients. There were no cases of postoperative CSF rhinorrhea, incisional CSF leak, or meningitis. Cosmetic results were comparable to those achieved using HAC alone. This cost-effective technique used only a third of the HAC required for traditional closure in which the entire mastoid defect is filled with cement, predisposing to infection. Postoperative CT and MRI showed excellent bony contouring and dural reconstitution, respectively. Conclusions. The authors report on successful use of titanium mesh HAC cranioplasty in preventing postoperative CSF leak after TLAN in all cases in their series. The titanium mesh provides a well-defined anatomical dissection plane that would make reoperation easier than working through scarred soft tissue. The mesh bolsters the fat graft and keeps HAC out of direct contact with mastoid air cells, thereby reducing the risk of infection. The cement cranioplasty does not preclude subsequent implantation of a bone-anchored hearing aid. ( Key Words cerebrospinal fluid leak postoperative infection mastoidectomy translabyrinthine resection acoustic neuroma titanium mesh vestibular schwannoma Postoperative CSF leak after translabyrinthine surgery for removal of an acoustic neuroma (TLAN) is recognized as an infrequent complication, despite the best prophylactic techniques currently available ,36,40,44 To prevent postoperative CSF leaks after Abbreviations used in this paper: HAC = hydroxyapatite cement; TLAN = translabyrinthine resection of acoustic neuroma (vestibular schwannoma). J Neurosurg / Volume 119 / July 2013 TLAN, several surgical methods have been tried, using different autografts and allografts, alone or in combinations, with varying success rates. 6,8,10,11,13,22 24,27,28,42,46 These range from calvarial bone autografts, bone cements, metals, and resins to resorbable bone plates. 5,6,51 Calvarial grafts can be time consuming and less mallea- This article contains some figures that are displayed in color on line but in black-and-white in the print edition. 113

2 S. Manjila et al. ble, and they are often vulnerable to significant remodeling over time. Methylmethacrylate and hydroxyapatite cement (HAC) have been used as feasible and effective methods of cranioplasty after TLAN, but complications such as postoperative infection are common. 37 Late plate exposure, plate fracture, and displacement are among the significant problems associated with these alloplasts. Similarly, different methods of tissue repair after translabyrinthine resection have been attempted. Several tissue types, including temporalis fascia, fascia lata, temporalis muscle, or adipose tissue, coupled with lumbar drainage for several days postoperatively, have been tried. The use of HAC with titanium mesh cranioplasty is based on the histological evidence of early osseous ingrowth into the HAC of the titanium mesh HAC construct noted after 6 months. These late osseous ingrowths that occur with bioactive materials such as HAC have been found to be useful in our case series, demonstrating long-term stability and pleasing cosmetic results after TLAN. 20 Some authors have shown that meticulous wound closure without opening of the facial recess, manipulation of the ossicles, or obliteration of the eustachian tube prevents postoperative CSF leak in TLAN. 22 However, enlarged translabyrinthine removal of vestibular schwannoma has been treated aggressively with blind closure of the external meatus, removal of the posterior bony canal wall, and obliteration of the eustachian tube and middle ear. Many surgical modifications (including total conservation of the fascioperiosteal flap, obliteration of petrosal cells that may have communicated with the middle ear, closing the attic with periosteum, and cautious removal of the incus in indicated cases) have contributed to the safety and efficacy of TLAN. If a CSF leak occurs despite these prophylactic methods, a lumbar drain is placed for 3 5 days as an initial step. However, in cases of persistent CSF leak, reexploring the wound, closing the ear canal, and packing the eustachian tube are recommended. Recently, an alternative method of transnasal endoscopic eustachian tube closure has been described by Kwartler and colleagues 39 for a CSF leak recurrence after translabyrinthine resection of acoustic schwannoma treated with traditional approaches including middle ear packing. We discuss a systematic surgical method of preventing CSF leak in TLAN by employing a multilayered closure using titanium mesh HAC cranioplasty. The pivotal scientific reasons behind the selection of various materials for this closure technique are detailed with a contemporary review of the related literature. 43,52 In 2010, we published a pilot study of this technique in 15 patients, demonstrating no evidence of postoperative CSF rhinorrhea or incisional leak. 7 Methods A retrospective chart review was conducted on 42 cases involving patients who underwent TLAN at University Hospitals Case Medical Center using this new technique from January 2006 to March The study was approved by our institutional review board. The patient group included 21 male patients and 21 female patients. Their mean age was 50.5 years (range years). Two patients had previously undergone Gamma Knife surgery. All patients presented with a unilateral vestibular schwannoma (acoustic neuroma) less than 3 cm in length: 12 lesions were intracanalicular, 2 were mostly in the cerebellopontine angle, and 28 were intracanalicular with a cisternal component. None of the patients had serviceable hearing (Grade III or IV on the Gardner-Robertson scale or Class C or D on the American Academy of Otolaryngology and Head & Neck Surgery classification). Surgical Technique Patients underwent standard translabyrinthine tumor resection. A large piece of temporalis fascia as well as a golf ball sized abdominal fat graft were harvested. After tumor resection, the following surgical steps were performed to seal the defect and close the wound (Fig. 1). The air cells in the posterior epitympanum or antrum were sealed off with bone wax to block the pathway to the middle ear. The dural leaves were reflected back and approximated as much as possible. A piece of Gelfoam (Pharmacia and Upjohn Company) was then laid over the internal auditory canal dura and posterior fossa dura. The temporalis fascia harvested earlier in the surgery was layered on top of the dural defect. Next, TISSEEL fibrin sealant (Baxter Healthcare Corporation) followed by a small piece of dural substitute DuraGen (Integra Neurosciences) was layered on top of the fascia, and more TISSEEL fibrin sealant was applied. A fat graft was obtained from the abdominal wall and placed over the sealed defect in the mastoid bowl. The fat was layered laterally to the level of the facial recess and filled to the level of cortical bone. The titanium mesh was appropriately sized and secured with miniscrews at 2 points medially on the bony margin. The free edge of the lateral mesh was bowed medially to compress the adipose graft, and the mesh was covered with hydroxyapatite paste and contoured to the bone of adjacent mastoid cortex (Fig. 2). The periosteum was then closed over the HAC in a watertight manner, with standard closure of soft tissue without a wound drain (Fig. 3). Results None of the patients was noted to have a postoperative CSF leak or pseudomeningocele after translabyrinthine cranioplasty using titanium mesh HAC; none required CSF diversion in the form of a temporary lumbar drain placement or a ventriculoperitoneal shunt after the TLAN. No postoperative cranial wounds or CNS infections were noted (Fig. 4). One patient had dehiscence of the abdominal fat graft donor site, which required surgical drainage. None required eustachian tube obliteration or any other middle ear procedures (Table 1). The duration of hospital stay in this series was short due to low overall morbidity of the procedure. The median duration of hospital stay was 2 days (range 1 7 days), and the median duration of ICU stay was 1 day (range 0 3 days). Discussion A translabyrinthine approach is used for the treatment of acoustic neuromas (vestibular schwannomas) 114 J Neurosurg / Volume 119 / July 2013

3 Prevention of CSF leaks after TLAN Fig. 1. Intraoperative photographs showing the surgical technique of wound closure following TLAN. A: Bone wax (black arrow) is applied to the posterior epitympanum to seal off the pathway to the middle ear. B: A temporalis fascia graft is placed over a layer of Duragen and TISSEEL sealant, which is applied initially over the internal auditory canal (IAC) dural and posterior fossa defect. C: TISSEEL fibrin sealant is again applied over the temporalis fascia to ensure a watertight closure. D: A piece of titanium mesh, which is secured with screws, holds all these layers down and helps to push them over the dural defect. E: A layer of HAC is applied over the mesh to provide excellent contour with the adjacent cortex. FN = facial nerve; IAC = internal auditory canal. when hearing is poor or in cases in which hearing preservation is unlikely.17,19 This approach provides the most direct route to the cerebellopontine angle and offers several advantages. It requires only minimal cerebellar retraction and affords a complete exposure of the internal auditory canal. Another advantage of this method is definite identification of the facial nerve in a fairly consistent and undisturbed location, anterior to the vertical crest at the fundus. In the event that the facial nerve is anatomically severed or not preserved, this approach offers the best visualization and exposure for an end-to-end neural anastomosis or placement of an interposition nerve graft. The mortality rate after TLAN is low, and the morbidities are usually associated with postoperative CSF leak or infection (Table 2).48,50,57 We believe that obliteration of the opened air cells with bone wax is the most important step in avoiding CSF leak after TLAN.26,53 Most surgeons use a dry sheet of Gelfoam to cover the dura before cement application as it facilitates graft adjustment without manipulation near the dura mater. We have used a layer of DuraGen with dural sealant before layering the temporalis fascia to ensure watertight closure. The traditional method of closure after TLAN uses an autologous fat graft. The use of an adipose graft helps to fill the dead space of mastoidectomy defect and to tamponade the dural defect that can potentially produce a CSF leak. Fat graft resorption over time and the resultant undesirable cosmetic indentation have been cited as the major issues with use of adipose graft.54 J Neurosurg / Volume 119 / July 2013 There is also an anecdotal report of a death caused by prolapse of adipose graft into the cerebellopontine angle after a translabyrinthine craniotomy.15 Our technique has therefore minimized the bulk of fat graft, and when supplemented peripherally with meshhac cover, it prevents the undesirable retroauricular cosmetic deformity from fat shrinkage. Some surgeons have tried using bone fragments mixed with fibrin glue replaced in the mastoid defect without using the fat graft for tamponade, especially after posterior petrosectomy, but these bone fragments had to be removed in some cases of postoperative meningitis or wound infections.44,57,58 We describe successful use of a multilayered watertight cranioplasty method in 42 TLAN patients, with no postoperative CSF leak to date. Early versus delayed CSF leaks are reported after TLAN and present as either incisional leaks or CSF otorhinorrhea, the latter being more common.1,9,12,21 These leaks could be the result of direct pressure exerted upon the porus acusticus in the immediate postoperative period until scarring around the air cells or the dural defect created a barrier to CSF leak. This mesh-apatite construct provides a tamponade effect, stabilizing the fat graft laid over the dura and waxed antrum.26,45,55 The described technique of using a titanium mesh provides this uniform steady pressure when the mesh is pushed down over the fat graft, which in turn provides room for HAC application that contours the retroauricular bony defect. The titanium mesh is bowed medially after screwing at 2 points to contour and stabilize the 115

4 S. Manjila et al. Fig. 2. Computed tomography scan demonstrating symmetric contouring of the surgically treated left mastoid cortex compared with the contralateral side. The arrow indicates hydroxyapatite. fat graft underlying the mesh. This can effectively seal the dural defect, thus preventing CSF leak or subgaleal CSF effusions/pseudomeningoceles. We used quick-setting HAC along with titanium mesh plate in all of our TLAN cranioplasties in this series. Although infections with fixation implants are not uncommon, titanium mesh has been used in neurosurgical cranioplasty for noninfected wounds with good cosmetic results and low infection rates. 1,9,12 In a series of 148 patients with titanium mesh cranioplasties reported on by Joffe and colleagues, 34 mesh explantation was necessary in only 1 case. In 206 delayed cranioplasties, Matsuno and colleagues 41 showed that titanium mesh has a remarkably low rate of infection compared with autologous bone, polymethyl methacrylate, or alumina-ceramics. An in vivo experiment demonstrated diminished bacterial adhesion to titanium compared with stainless steel, polymethyl methacrylate, and cobalt-chrome. 14,16 The safety of titanium mesh cages has been demonstrated in the setting of hematogenous infections, local vertebral osteomyelitis, and active wound infections. 14,16 Likewise, postcraniotomy surgical site infections have been effectively treated using titanium mesh cranioplasty in a recent report published by Kshettri and colleagues. 38 Titanium is a nonferrous metal, is relatively radiolucent, and causes no significant degradation on either CT or MRI. It is biocompatible and corrosion-resistant and has a modulus of elasticity more comparable to in vivo bone than other metals. 14,16,35 Its ability to act as a stable scaffold for HAC in weightbearing portions of the maxillofacial skeleton has been published before in the related literature. Concurrently, HAC consists of a calcium phosphate Fig. 3. Illustration of the multilayer closure of a translabyrinthine wound using HAC and titanium mesh cranioplasty showing the surgical bed after resection of a tumor from the IAC (A), layering of temporalis fascia (B), use of dural sealant for watertight dural closure (C), free fat graft placement in the mastoid bowl (D), titanium mesh placed over the depressed fat graft (E), and HAC layered over the mesh prior to layered skin closure (F). EAC = external auditory canal; SS = sigmoid sinus. Copyright 2012 Maroun T. Semaan. compound in a hexagonal structure, a synthetic duplicate of the natural mineral, and has been shown to facilitate bony ingrowth over time. 2,4,52,56 There has been evidence of integration of new bone into the HAC at the periphery of the lesion with no foreign body reaction or inflammatory response, even in animal models. In a series of 54 patients with HAC, Arriaga and Chen 2 reported a reduction in CSF leak from 12.5% to 3.7% when compared with a similar-sized cohort in which only autologous fat was used. In an update to the study expanded to 108 patients followed over 4 years, the authors reported only one additional CSF leak with an extra 90 patients included who had no wound complications. 3 An additional study using HAC in both translabyrinthine and retrosigmoid approaches for the resection of 33 acoustic neuromas by Kruger and colleagues 37 noted one case of CSF leakage. With use of HAC cranioplasty, there have been issues with postoperative infections. In a series reported by Ridenour and colleagues, 47 all patients in whom this technique was used required removal of the cement due to extensive skull base osteitis and delayed failure of inte- 116 J Neurosurg / Volume 119 / July 2013

5 Prevention of CSF leaks after TLAN have used HAC in our cranioplasty, though in much lesser amounts to ensure that the technique is cost-effective and to reduce the chance of infection, especially by keeping it out of direct contact with mastoid air cells. Fig. 4. Postoperative MR images obtained 1 month (left) and 12 months (right) after surgery showing minimal changes to the fat graft (asterisk) with no significant resorption. The dural defect, which had been reestablished using fascia and DuraGen, appears smooth and in continuity with the native dura. There are no signs of CSF accumulation in the wound area. The arrows indicate the reconstructed dural defect. gration with adjacent bone. Zins and colleagues 58 reported on a series of 16 patients, with specific comments on HAC-associated increased morbidity; 50% of the patients presented with a major complication as late as 6 years after the initial operation wherein bone cement was used in the repair of large skull base defects. In their case series, the mean amount of bone cement used was 80 g. We TABLE 1: Characteristics of patients who underwent titanium mesh HAC cranioplasty after TLAN* Variable J Neurosurg / Volume 119 / July 2013 Value no. of cases 42 mean age (yrs) 50.5 ± 12.2 sex (M/F) 21/21 mean tumor diameter (cm) 1.51 ± 0.58 prior GKS 2 LOH median 2 range 1 7 ICU stay (days) median 1 range 0 3 tumor location IAC 12 CPA 2 IAC + CPA 28 complications CSF rhinorrhea 0 incisional CSF leak 0 pseudomeningocele 0 postop hematoma 0 abdominal fat graft donor site issues 1 * Values represent numbers of cases unless otherwise indicated. Means are presented with SD. Abbreviations: CPA = cerebellopontine angle; GKS = Gamma Knife surgery; IAC = internal auditory canal; LOH = length of hospital stay. Dehiscence. Cosmetic Mastoidectomy Local Autograft? Hydroxyapatite cement can be expensive if employed in large quantities, so some surgeons prefer the use of a vascularized bone flap to achieve the same end without alloplastic materials. Cosmetic mastoidectomy was employed to cover larger defects in posterior petrosectomies in the 1990s. 18,25,43,49,54,55 However, the outer table of mastoid bone needed for a posttranslabyrinthine defect is smaller; therefore, it is cumbersome to perform a cortical bone flap such as those described for larger petrosectomies. Even if a rongeur or air drill were used, there would still be a circumferential bony defect around the bone flap, and it would be wide enough to require sealing and miniplate fixation. If a larger split-thickness mastoid flap were raised, it would require more extensive soft tissue dissection than actually required for a regular TLAN procedure. We feel that harvesting and using a periosteal flap represents a less efficient use of time and so advocate the use of titanium mesh for cranioplasty. Resorbable Plate Cranioplasty an Option? In a recent study published in 2011, Hillman and colleagues 31 demonstrated the safety and feasibility of using resorbable plate cranioplasty securing the fat graft, with a CSF leak rate equivalent to fat grafting alone. Of 71 patients in the study group and 149 patients in the control group, respectively, 12.7% in the study group and 13.4% in the control group developed CSF leak after translabyrinthine resection of cerebellopontine angle tumors in a prospective clinical trial. There was no change in the rate of surgical revision or lumbar drain placement in either study group. More studies with a larger sample population will be necessary to demonstrate the efficacy of this technique. The main advantage of alloplastic materials in general is the lack of potential added donor-site morbidity. 4,31 Any urgent reentry to the mastoid cavity or the posterior fossa can be easily performed with the closure technique demonstrated in our case series. As of the close of our study, none of the patients had required reoperations for tumor regrowth or wound-related problems. For a reoperation, no significant time is wasted in the removal of a huge HAC block during reentry; instead, the titanium mesh cranioplasty screws are identified easily and the wound reopened expeditiously. Bone-Anchored Hearing Aid The translabyrinthine approach leaves patients with only one hearing ear. Several studies have shown that patients benefit from either a contralateral routing of sound or a bone-anchored hearing aid (in comparison with patients with no hearing rehabilitation). 19,30,45 Patients provided with a bone-anchored hearing aid have better speech recognition in quiet and noisy conditions than patients with contralateral routing of sound. 27,30 Our surgical technique does not interfere with the placement of a bone-anchored hearing aid in its typical position. 117

6 S. Manjila et al. TABLE 2: Summary of relevant studies on surgical techniques to prevent CSF leak and published results* Authors & Year No. of Procedures (no. of CSF leaks) Site of CSF Leak Prophylactic Surgical Technique Becker et al., (13) rhinorrhea, incisional fat graft Arriaga & Chen, (9) total, 47 (0) unspecified fat graft + HAC after using HAC Brennan et al., (43) rhinorrhea, incisional, otorrhea fat graft + fascia + ET packing Mass et al., (20) rhinorrhea, incisional fat graft + ET packing Gal & Bartels, (0) none fat graft + bone wax Celikkanat et al., (8) rhinorrhea fat graft + bone wax + mastoid pressure dressing Gillman & Parnes, (6) unspecified fat graft + temporalis muscle + fascia + mastoid pressure dressing Hoffman, (31) rhinorrhea, incisional fat graft + fascia + mastoid pressure dressing Pulec, (2) incisional fat graft + temporalis muscle + fascia + ET packing/obliteration + mastoid pressure dressing Rodgers & Luxford, (49) unspecified fat graft+ mastoid pressure dressing Bryce et al., (23) rhinorrhea, incisional, otorrhea fat graft + temporalis muscle + fascia + ET packing/obliteration Hardy et al., (13) unspecified fat graft + fascia + ET packing current study 42 (0) none fascia + fat graft + bone wax + titanium mesh + HAC * ET = eustachian tube. The cost of this multilayered cranioplasty includes 1 1 mm of DuraGen (dural substitute) at $185 ($315 for 2 2 mm), 3 ml of HydroSet (Stryker, hydroxyapatite bone cement) at $865 ($1385 for 5 ml), mm ( mm thick) of titanium mesh at $2110, and 4 ml of TISSEEL (glue) at $300 ($690 for 10 ml). These expenses are negligible compared with a readmission required for a postoperative CSF leak or meningitis. Conclusions This novel reconstruction method using titanium mesh HAC cranioplasty has been successfully used in preventing CSF leaks or pseudomeningocele formation after TLAN. The complementary supporting effect of bowing titanium mesh with the HAC cranioplasty has reduced the incidence of postoperative CSF leaks. Titanium mesh provides excellent tissue planes and prevents the HAC from coming in contact with mastoid air cells, thus reducing infection. The technique is quick and easy to perform, provides good cosmetic results, offers rapid access in reoperations, and does not preclude subsequent implantation of a bone-anchored hearing aid. Disclosure The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. Author contributions to the study and manuscript preparation include the following. Conception and design: Bambakidis. Acquisition of data: Bambakidis, Semaan, Megerian. Analysis and interpretation of data: all authors. Drafting the article: Bambakidis, Manjila, Weidenbecher, Semaan. Critically revising the article: Bambakidis. Reviewed submitted version of manuscript: Bambakidis. Approved the final version of the manuscript on behalf of all authors: Bambakidis. References 1. Arens S, Schlegel U, Printzen G, Ziegler WJ, Perren SM, Hansis M: Influence of materials for fixation implants on local infection. An experimental study of steel versus titanium DCP in rabbits. J Bone Joint Surg Br 78: , Arriaga MA, Chen DA: Hydroxyapatite cement cranioplasty in translabyrinthine acoustic neuroma surgery. Otolaryngol Head Neck Surg 126: , Arriaga MA, Chen DA, Burke EL: Hydroxyapatite cement cranioplasty in translabyrinthine acoustic neuroma surgery update. Otol Neurotol 28: , Ascherman JA, Foo R, Nanda D, Parisien M: Reconstruction of cranial bone defects using a quick-setting hydroxyapatite cement and absorbable plates. J Craniofac Surg 19: , Baird CJ, Hdeib A, Suk I, Francis HW, Holliday MJ, Tamargo RJ, et al: Reduction of cerebrospinal fluid rhinorrhea after vestibular schwannoma surgery by reconstruction of the drilled porus acusticus with hydroxyapatite bone cement. J Neurosurg 107: , Bambakidis NC, Megerian CA, Spetzler RF (eds): Surgery of the Cerebellopontine Angle. Shelton, CT: BC Decker, Bambakidis NC, Munyon C, Ko A, Selman WR, Megerian CA: A novel method of translabyrinthine cranioplasty using hydroxyapatite cement and titanium mesh: a technical report. Skull Base 20: , Becker SS, Jackler RK, Pitts LH: Cerebrospinal fluid leak after acoustic neuroma surgery: a comparison of the translabyrinthine, middle fossa, and retrosigmoid approaches. Otol Neurotol 24: , Blake GB, MacFarlane MR, Hinton JW: Titanium in reconstructive surgery of the skull and face. Br J Plast Surg 43: , Brennan JW, Rowed DW, Nedzelski JM, Chen JM: Cerebrospinal fluid leak after acoustic neuroma surgery: influence of tumor size and surgical approach on incidence and response to treatment. J Neurosurg 94: , Bryce GE, Nedzelski JM, Rowed DW, Rappaport JM: Cerebrospinal fluid leaks and meningitis in acoustic neuroma surgery. Otolaryngol Head Neck Surg 104:81 87, J Neurosurg / Volume 119 / July 2013

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8 S. Manjila et al. droxyapatite: an alternative method of frontal sinus obliteration. Otolaryngol Clin North Am 34: , Stieglitz LH, Giordano M, Gerganov V, Raabe A, Samii A, Samii M, et al: Petrous bone pneumatization is a risk factor for cerebrospinal fluid fistula following vestibular schwannoma surgery. Neurosurgery 67 (2 Suppl Operative): , Taguchi Y, Matsuzawa M, Sakakibara Y, Sekino H: En bloc mastoidectomy to avoid postoperative retroauricular deformity in the transpetrosal approach. J Clin Neurosci 5: , Tokoro K, Chiba Y, Murai M, Hayashi A, Kyuma Y, Fujii S, et al: Cosmetic reconstruction after mastoidectomy for the transpetrosal-presigmoid approach: technical note. Neurosurgery 39: , Verret DJ, Ducic Y, Oxford L, Smith J: Hydroxyapatite cement in craniofacial reconstruction. Otolaryngol Head Neck Surg 133: , Yuen HW, Chen JM: Reconstructive options for skull defects following translabyrinthine surgery for vestibular schwannomas. Curr Opin Otolaryngol Head Neck Surg 16: , Zins JE, Moreira-Gonzalez A, Papay FA: Use of calciumbased bone cements in the repair of large, full-thickness cranial defects: a caution. Plast Reconstr Surg 120: , 2007 Manuscript submitted July 10, Accepted November 30, Please include this information when citing this paper: published online January 25, 2013; DOI: / JNS Address correspondence to: Nicholas C. Bambakidis, M.D., Department of Neurological Surgery, The Neurological Institute, University Hospitals Case Medical Center, Cleveland, Ohio Nicholas.Bambakidis2@UHhospitals.org. 120 J Neurosurg / Volume 119 / July 2013