With advances in microsurgical techniques and the. Staged resection of large vestibular schwannomas. Clinical article

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1 J Neurosurg 116: , 2012 Staged resection of large vestibular schwannomas Clinical article Ahmed M. Raslan, M.D., 1 James K. Liu, M.D., 3 Sean O. McMenomey, M.D., 1,2 and Johnny B. Delashaw Jr., M.D. 1,2 Departments of 1 Neurological Surgery and 2 Otolaryngology, Oregon Health & Science University, Portland, Oregon; and 3 Department of Neurological Surgery, Center for Skull Base and Pituitary Surgery, Neurological Institute of New Jersey, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark, New Jersey Object. Staged resection of large vestibular schwannomas (VSs) has been proposed as a strategy to improve facial nerve outcomes and morbidity. The authors report their experience with 2-stage resections of large VSs and analyze the indications, facial nerve outcomes, surgical results, and complications. The authors compare these results with those of a similar cohort of patients who underwent a single-stage resection. Methods. A retrospective review of all patients (age > 18 years) who underwent surgery from 2002 to 2010 for large ( 3 cm) VSs at the authors institution with a minimum of 6 months follow-up was undertaken. A first-stage retrosigmoid approach (without meatal drilling) was performed to remove the cerebellopontine angle portion of the tumor and to decompress the brainstem. A decision to stage the operation was made intraoperatively if there was cerebellar or brainstem edema, excessive tumor adherence to the facial nerve or brainstem, a poorly stimulating facial nerve, or a thinned or splayed facial nerve. A second-stage translabyrinthine approach was performed at a later date to remove the remaining tumor. The single-stage resection consisted of a retrosigmoid approach with meatal drilling. Patient charts were evaluated for tumor size, extent of resection, tumor recurrence, House-Brackmann facial nerve function grade, and complications. Results. Twenty-eight and 19 patients underwent 2- or single-stage resection of a large VS, respectively. The average tumor size was 3.9 cm (range cm) in the 2-stage group and 3.9 cm (range cm) in the single-stage group. The mean follow-up was 36 ± 19 months in the 2-stage group versus 24 ± 14 months in the single-stage group. Gross-total or near-total resection was achieved in 27 (96.4%) of 28 patients in the 2-stage group and 15 (79%) of 19 patients in the single-stage group (p < 0.01). Anatomical facial nerve preservation was achieved in all but 1 patient (94.7%), and there were no recurrences on follow-up imaging in the 2-stage group. Good facial nerve functional outcome (House-Brackmann Grades I and II) at last follow-up was achieved in 23 (82%) of 28 patients in the 2-stage group and 10 (53%) of 19 patients in the single-stage group (p < 0.01). Cerebrospinal fluid leak related complications (intracranial hypotension, blood patch, and lumboperitoneal shunt for pseudomeningocele) were more common in the 2-stage group. There were no postoperative strokes, hemorrhages, or deaths in either group. Conclusions. The authors results suggest that staged resection of large VSs may potentially achieve better facial nerve outcomes. There does not appear to be added neurological morbidity with staged resections. ( Key Words vestibular schwannoma acoustic neuroma retrosigmoid translabyrinthine staged resection facial nerve With advances in microsurgical techniques and the introduction of radiosurgery, treatment outcome for most VSs has substantially improved with greater quality of life and increased survival. However, large ( 3 cm) VSs still pose a challenge; they may not be good candidates for radiosurgery, are often symptomatic from pressure on adjacent structures, and are associated with poor facial nerve functions. Most contemporary series report very good safety and resectability of large VSs; Abbreviations used in this paper: CPA = cerebellopontine angle; GTR = gross-total resection; IAC = internal auditory canal; VS = vestibular schwannoma. however, facial nerve functional outcome remains a challenge following successful resection. 2 4 It is not clear in the literature whether staged resections of large VSs result in improved facial nerve outcomes and fewer surgery-related complications. There are no clear indications for staging, and optimal timing between surgeries is not well defined. There is also a concern as to whether more complications become an issue with additional surgeries. This article contains some figures that are displayed in color on line but in black-and-white in the print edition J Neurosurg / Volume 116 / May 2012

2 Staged resection of large vestibular schwannomas At the Oregon Health & Science University, we selectively began performing staged resections of large ( 3 cm) VSs in A staging decision was made intraoperatively based on individual surgical case findings. Additionally, we began tailoring the interval between procedures to achieve improved facial nerve outcome after the first stage. We report our experience with staged resection of large VSs and analyze the indications, facial nerve outcomes, surgical results, and complications. Methods Chart Analysis A retrospective chart analysis of patients treated for resection of a large ( 3 cm) VS, performed by a single neurosurgeon (J.B.D.), at the Oregon Health & Science University between 2002 and 2010 was undertaken. The study was approved by the Oregon Health & Science University Institutional Review Board. Demographic information for each patient was gathered from inpatient and outpatient clinic notes, operative reports, and pre- and postoperative images. Patient charts were evaluated for tumor size, extent of resection, tumor recurrence, House-Brackmann facial nerve function grade at discharge after each operation and at the most recent follow-up, and complications. Facial nerve grading was performed and agreed on by the senior neurosurgeon (J.B.D.) and the neurootologist (S.O.M.). The results of a 2-stage procedure group were compared with those of a single-stage procedure group. Criteria for Staging All patients with VSs 3 cm or larger in diameter were counseled and consented preoperatively in regard to the possibility of undergoing a 2-stage surgery. It is rare that functional hearing is preserved when large tumors are resected; therefore, all patients were informed preoperatively that hearing preservation was not a likely goal. Ultimately, the decision of a single- or 2-stage resection was made intraoperatively based on the following criteria: thin and flattened/splayed facial nerve, weakly stimulating facial nerve (> 0.1 ma), significant adherence of tumor to the facial nerve resulting in difficult dissection, and a soft or edematous brainstem or cerebellum. Once the decision to perform a 2-stage procedure was made, facial nerve function after surgery dictated the duration of the interval between the 2 procedures. If facial nerve function was House-Brackmann Grade I or II, then the second stage was usually undertaken within 2 4 weeks of the first stage. If facial nerve function was otherwise, a typical interval of around 6 months usually followed, which permitted healing or recovery of the facial nerve prior to the second stage. Surgical Procedure Two-Stage Resection. A first-stage retrosigmoid approach (without meatal drilling) was performed to remove the CPA portion of the tumor and to decompress the brainstem. A decision to stage the operation was made intraoperatively based on the aforementioned criteria, and the J Neurosurg / Volume 116 / May 2012 IAC was not drilled but preserved for the second-stage translabyrinthine approach. A lumbar drain was used during surgery and was removed after the procedures. A large C-shaped retroauricular incision was used to more easily facilitate the second-stage translabyrinthine approach. A sheet of Gelfilm (Upjohn Co.) (absorbable gelatin film) was placed on the brainstem, allowing separation of the brainstem from residual tumor. Gelfilm was used to reduce inflammatory adhesions and to help identify the facial nerve at the brainstem because it remains intact after 6 months, which was the planned interval between the 2 stages if facial nerve function was not House-Brackmann Grade I or II after the surgery. At the conclusion of the first-stage retrosigmoid approach, a cranioplasty with titanium mesh to protect the dura and allow easier exposure at the second stage was undertaken. Figure 1 demonstrates brainstem decompression and major debulking achieved by the firststage retrosigmoid approach. A second-stage translabyrinthine approach was performed at a later date to remove the remaining tumor. A lumbar drain was inserted and left in place postoperatively to prevent a postoperative CSF leak. The previous C-shaped incision was extended anteriorly to allow exposure of the mastoid, and the IAC was exposed at the lateral end of the facial nerve with virgin dissection planes. Facial nerve monitoring was performed in all cases. After resection of the residual tumor, the middle ear was occluded with muscle, and the mastoid was packed with fat graft, followed by a cranioplasty with titanium mesh and Norian (Synthes) bone cement. The differences in trajectories and surgical angles between the retrosigmoid and translabyrinthine approaches are shown in Fig. 2. Single-Stage Resection. A single-stage resection via a retrosigmoid approach with meatal drilling was performed if the criteria for staging were not met. The technique used was similar to the first stage of the 2-stage approach but with an attempt to radically remove tumor. Results Patient Population The study included 47 patients (27 men and 20 women) who underwent microsurgical resection of a large ( 3 cm) VS. Twenty-eight and 19 patients underwent 2- and single-stage resections of large VSs, respectively. In the 2-stage group (14 men), the mean age was 45.2 ± 11 years (range years). In the single-stage group (13 men), the mean age was 52.7 ± 15 years (range years). All tumors were sized on the basis of their maximal transverse diameter on preoperative imaging, and the average tumor size in all 47 patients was 3.9 ± 0.8 cm (range cm). The average tumor size was 3.9 ± 0.5 cm (range cm) in the single-stage group and 3.9 ± 0.9 cm (range cm) in the 2-stage group (Table 1). There was no difference in procedure time between the single-stage group (4.4 ± 0.7 hours) and each stage of the 2-stage group (4.7 ± 0.9 and 4.3 ± 0.7 hours) (Table 1). Nineteen patients (67.8%) in the 2-stage group and 12 patients (63.2%) in the singlestage group had effacement of the fourth ventricle. Five 1127

3 A. M. Raslan et al. Fig. 1. A: Illustration depicting the tumor prior to resection in the CPA angle, with brainstem and facial nerve compression. B: Illustration of the exposure of tumor facial nerve interface and cerebellar retraction in the retrosigmoid approach, partial tumor resection, and decompression of the brainstem. C: Illustration of the exposure of the tumor facial nerve interface from a presigmoid angle, completed tumor resection with removal of the IAC portion. Illustrations printed with permission from Oregon Health & Science University. patients in the 2-stage group and 3 patients (15.8%) in the single-stage group presented with hydrocephalus. The mean follow-up duration for the 2-stage group was 36 ± 19 months (range 4 84 months), and that for the single-stage group was 24 ± 14 months (range 5 60 months). All patients had Class C or D (American Academy of Otolaryngology Head and Neck Surgery classification) preoperative hearing.3 The primary outcome measurement postsurgery was facial nerve function in each group. We considered HouseBrackmann Grades I and II as good facial nerve functional outcomes and House-Brackmann Grades III, IV, V, and VI as poor facial nerve functional outcomes. In the 2-stage group, 28.6% of the patients (8 of 28) had poor facial nerve function immediately after the procedure, which improved to 18% (5 of 28) before the second-stage translabyrinthine approach. After waiting 6 months for those with poor facial nerve function, 3 of 8 patients improved with regard to facial nerve function from poor to good function. After the second stage, 50% (14 of 28) of the patients exhibited poor facial nerve function, which improved to 18% (5 of 28) at the last documented follow-up (average 36 months) (Figs. 3 and 4). In the single-stage group, 63.2% (12 of 19) of patients had poor facial nerve functional outcome immediately after the procedure (Fig. 4). At the last documented followup (average 24 months) 47% (9 of 19) of patients had poor facial nerve functional outcome. A chi-square test demonstrated a statistically signifi1128 cant difference between good facial nerve functional outcome at the last documented follow-up between the 2-stage and single-stage groups (p < 0.01) (Fig. 3). Structural integrity of the facial nerve was preserved in 92.86% (26 of 28) of patients in the 2-stage group and in 84% (16 of 19) of patients in the single-stage group. Subsequently, 2 and 3 patients underwent facial-hypoglossal anastomosis procedures in the 2-stage and single-stage groups, respectively. Gross-total resection (total + near-total resection) was achieved in 96.4% (27 of 28) in the 2-stage group versus 78.9% (15 of 19) in the single-stage group. A chi-square test demonstrated a statistically significant difference in percentage of achieved GTR between the 2-stage and the single-stage groups (p < 0.01). In the 2-stage group, 1 patient with subtotal resection underwent radiosurgery for the residual tumor versus 3 patients in the singe-stage group. Radiosurgery was indicated for the residual tumors that demonstrated growth on subsequent follow-up images (Fig. 5). There were no deaths in this series; procedure complications are listed in Table 2. The most common complication in the 2-stage group was related to CSF leakage in the form of spinal headache or pseudomeningocele, which occurred in a total of 8 patients, 4 of whom required blood patch to seal a lumbar leak and 4 who required a lumbar peritoneal shunt to treat a pseudomeningocele. In the single-stage group, a blood patch was required in 2 patients, and no patient needed a lumbar peritoneal shunt. Nine paj Neurosurg / Volume 116 / May 2012

4 Staged resection of large vestibular schwannomas TABLE 1: Summary of patient, surgical, and postsurgical characteristics in the 2-stage and single-stage groups* Variable 2-Stage Single-Stage Fig. 2. Illustration demonstrating the differences in trajectory and surgical angle between the retrosigmoid and translabyrinthine approaches that allow for a different perspective of the tumor facial nerve interface. Illustration printed with permission from Oregon Health & Science University. tients in each group required a gold weight to treat facial weakness. Illustrative Cases Case 1. This 36-year-old woman presented with leftsided hearing loss, imbalance, and headaches. Magnetic resonance imaging demonstrated a 5-cm VS with brainstem compression (Fig. 6). The patient s preoperative hearing was nonserviceable. An initial retrosigmoid approach was performed to remove the majority of the CPA portion of the tumor and to decompress the brainstem. At surgery, the facial nerve was extremely thin, flattened, and adherent to the tumor. A second stage was planned during which GTR was performed with preservation of the facial nerve. At the 9-month follow-up, the patient was neurologically intact with House-Brackmann Grade I facial nerve function. Case 2. This 51-year-old man presented with progressive right-sided hearing loss. Magnetic resonance imaging demonstrated a 4-cm VS with brainstem compression (Fig. 7). The patient was completely deaf in the right ear. An initial retrosigmoid approach was performed to remove the majority of the CPA portion of the tumor and to decompress the brainstem. A decision was made to return and perform a second-stage translabyrinthine approach to remove the residual tumor. At the second surgery, the facial nerve was extremely adherent to the tumor. A near-total J Neurosurg / Volume 116 / May 2012 total no. of patients sex (M/F) 14:14 13:6 age (yrs) mean 45.2 ± ± 15 range clinical presentation (no.) hearing loss imbalance tinnitus 7 7 headache 7 5 facial numbness 5 3 facial weakness 3 3 previous GKS 3 MRI findings (no.) CPA mass brainstem compression th ventricle effacement hydrocephalus 5 3 VS size (cm) mean 3.9 ± ± 0.5 range resection (no.) GTR total near-total 6 5 subtotal 1 4 gold weight treatment (no.) 9 9 facial-hypoglossal anastomosis (no.) 2 3 lumboperitoneal shunt (no.) 4 1 radiosurgery (no.) 1 3 follow-up (mos) mean 36 ± ± 14 range interval btwn stages (wks) mean 12 ± 15 range 2 78 procedure time (hrs) suboccipital 4.7 ± ± 0.7 translabyrinthine 4.3 ± 0.7 * GKS = Gamma Knife surgery. resection (> 95%) was performed to preserve facial nerve function, and the patient had House-Brackmann Grade II facial nerve function at last follow-up (27 months) with no recurrence of the tumor. Discussion Surgical removal of large VSs (generally 3 cm) is as- 1129

5 A. M. Raslan et al. Fig. 3. Good (House-Brackmann Grade I or II) versus poor (House- Brackmann Grade III IV) facial nerve function in the 2-stage and single-stage groups at the last documented follow-up. A statistically significant difference between groups is noted. HB = House-Brackmann. sociated with higher rates of facial nerve dysfunction and complications than smaller tumors. Large VSs are usually associated with some degree of brainstem compression, effacement of the fourth ventricle with or without resultant hydrocephalus, and displacement of multiple cranial nerves within the CPA, including the trigeminal nerve, facial nerve, vestibular and cochlear nerves, and the lower cranial nerves. Due to the large size of these tumors, dissection off of the brainstem and cranial nerves can sometimes be difficult. There is a relationship between VS size and facial nerve functional outcome after surgery, with a much lower likelihood of facial nerve function preservation (defined as House-Brackmann Grade I or II) with larger tumors ( 3 cm) 7 and vice versa, a greater chance of facial nerve Fig. 5. Bar graph showing GTR in the 2-stage versus single-stage groups. STR = subtotal resection. preservation with tumors 2 cm or smaller. 6 Excellent facial nerve function (House-Brackmann Grade I or II) after resection of large vestibular schwannomas has been reported to range from 30% to 84% (Table 3). 1,4,7,8,10,14 17 Some authors have grouped House-Brackmann Grades I IV as acceptable facial nerve function; 7 however, others would argue that House-Brackmann Grades III and IV may not be acceptable from the patients perspective. 11,13 In other words, facial nerve function, as measured by House-Brackmann grade, is viewed less favorably by the patient than by the physician s estimation of the same House-Brackmann grade. Therefore, we elected to designate only House-Brackmann Grades I and II as good outcomes. In cases of large tumors, it is generally accepted that hearing preservation is extremely unlikely and should not influence the choice of surgical approach. 1,7 Staged resection can be performed in some cases in TABLE 2: Summary of complications in the 2-stage and singlestage groups* Complication 2-Stage (n = 28) Group Single-Stage (n = 19) Fig. 4. Bar graph showing the progress of facial nerve functional outcome after each component of the 2-stage and the single-stage approach. FU = follow-up; RS = retrosigmoid; TL = translabyrinthine. disruption of CN VII 2 2 spinal HA & blood patch 4 2 hydrocephalus (VPS placement) 0 2 wound infection 2 1 pseudomeningocele & LP shunt 4 0 meningitis 1 1 sinus thrombosis 1 0 intestinal obstruction 0 1 DVT 2 0 * CN = cranial nerve; DVT = deep venous thrombosis; HA = headache; LP = lumboperitoneal; VPS = ventriculoperitoneal shunt J Neurosurg / Volume 116 / May 2012

6 Staged resection of large vestibular schwannomas Fig. 6. Case 1. Preoperative (A), postretrosigmoid (B), and posttranslabyrinthine (C) MRI studies showing 2-stage resection of a VS that was larger than 3 cm. Gross-total resection is evident on the postoperative MRI study. an attempt to minimize morbidity. Staging the resection has been proposed as a strategy to improve facial nerve outcomes and minimize complications. 2,12 Comey et al. 2 reported on 83 patients with VSs larger than 3 cm who underwent staged resection, all via a suboccipital retrosigmoid approach, over a 20-year time period that spanned from 1972 to Ninety-five percent of patients underwent 2-stage procedures and 5% underwent procedures that comprised at least 3 stages. The authors operative strategy was to debulk the lateral aspect of the tumor during the first stage and then wait for the tumor to decompress out of the brainstem on follow-up imaging before removing the remaining tumor. It was noted that there was less vascularity and less adherence to the brainstem during the second operation. The facial nerve was preserved in 72%, and GTR was accomplished in 89% with a recurrence rate of 2.4%. Facial nerve outcome at the latest follow-up was reported as an average House-Brackmann grade of III. Unfortunately, the authors did not report the percentage of patients attaining a House-Brackmann grade of I or II. The authors also did not mention if facial nerve monitoring was used or whether the IAC was drilled out to remove the intracanalicular portion of the tumor. The study was also performed partly in the pre-mri era and CT scanning was used for follow-up imaging, which does not adequately detect residual or recurrent tumor as measured by today s imaging standards. In contrast to the above strategy of performing all stages through the same approach, we performed the 2 stages with separate operative approaches, that is, retrosigmoid and translabyrinthine. This offers the advantage of having fresh tissue planes, specifically at the lateral end of the IAC during the translabyrinthine stage, which offers early identification of the facial nerve. Rather than debulking the lateral aspect of the tumor, as described by Comey et al., 2 our strategy was to debulk the tumor medially during the retrosigmoid stage. This allows decompression off of the brainstem and identification of the facial nerve at the brainstem by using a facial nerve stimulator. The latter is important because it guides the tumor resection off of the facial nerve from a medial-to-lateral direction with confirmation of a neurophysiologically conducting facial nerve. The 2 approaches provide 2 different perspectives (Fig. 2) of the facial nerve close to the internal auditory meatus, which is the region hidden by the residual tumor and is a potential site for nerve injury during resection. Yamakami et al. 17 and Godefroy et al. 4 reported 84% and 78% good facial nerve outcome (House-Brackmann Grades I and II) in their series; however, they achieved GTR in only 86% and 26%, respectively. On the other hand, Samii et al. 14 reported a large series with complete resection in 100% of patients. Good facial nerve outcome was achieved in only 44% of tumors larger than 3.9 cm. When choosing a single approach to remove large VSs, a tradeoff between facial nerve outcome and extent of resection is a dilemma. High percentages of total resections are associated with worse facial nerve outcomes and vice versa. A 2-stage approach allows for maximum tumor resection and an increased percentage of patients with good facial nerve outcome. Fig. 7. Case 2. Preoperative (A), postretrosigmoid (B), and posttranslabyrinthine (C) MRI studies showing near-total resection of a VS after 2-stage resection. J Neurosurg / Volume 116 / May

7 A. M. Raslan et al. TABLE 3: Summary of facial nerve outcome of large VSs treated by a single approach in previously published series Authors & Year House-Brackmann Grade I or II (%) Size (cm) Approach Briggs et al., >4 translabyrinthine Naguib et al., >2.5 translabyrinthine Lanman et al., >3 translabyrinthine Wu & Sterkers, >3 translabyrinthine Sluyter et al., >3 translabyrinthine Mamikoglu et al., >3 translabyrinthine Yamakami et al., * >3 retrosigmoid Samii et al., <3.9 retrosigmoid 44 >3.9 retrosigmoid Godefroy et al., >2.6 translabyrinthine * Gross-total resection was achieved in 86% of patients. Gross-total resection was achieved in only 26% of patients. A similar staging strategy to the one we used was used by Patni and Kartush, 12 in which staging was planned preoperatively in 34 patients with large VSs. All patients had total or near-total resection with no recurrences at a mean follow-up of 6 years, and 94% had House-Brackmann Grade I or II facial nerve function at the latest follow-up. Our strategy was unique in that the decision to stage the operation was made intraoperatively based on surgical findings. Our strategy was also unique in that we allowed patients with poor facial nerve function after the first stage to recover their facial nerve function prior to pursuing the second stage. We propose that this strategy is responsible for the good facial nerve outcome in the 2-stage group since it divides the surgical trauma between 2 surgeries and allows a recovery period for the facial nerve. These results further validate the report of Patni and Kartush, 12 who reported a higher percentage (94%) of good facial nerve function and 98% GTR. An alternative to the 2-stage approach is a single-stage approach followed by radiosurgery of the residual tumor, given the good facial nerve outcomes reported after radiosurgery for smaller VSs. 9 Iwai et al. 5 reported a series of 14 patients with large VSs (> 3 cm) in which subtotal resection was performed and followed by radiosurgery to the residual tumor, a strategy that resulted in 86% (12 of 14) of patients with good facial nerve function at their last followup. However, 3 of 14 patients continued to have progression of the residual tumor size, achieving a gross control rate of 78% (11 of 14 patients). Cerebrospinal fluid related complications were more prevalent in the 2-stage group, specifically in relation to the translabyrinthine approach; however, no permanent morbidity was incurred due to the CSF complications. Finally, we acknowledge the inherent retrospective study limitations and biases, including the fact that the 2 groups were not matched (for example, regarding followup duration and mean age), the absence of an unbiased third party to evaluate facial nerve outcome, and the arbitrary surgical strategy selected by the surgeon. Readers are advised to consider these limitations when interpreting the study results and when attempting to answer the question of what is the best surgical strategy for large VSs. Conclusions Our results suggest that staged resection of large VSs may potentially achieve better facial nerve outcomes while allowing maximum tumor resection with no additional neurological morbidity. Disclosure Dr. Delashaw is a consultant for Covidien. Author contributions to the study and manuscript preparation include the following. Conception and design: all authors. Acquisition of data: Raslan, Liu, McMenomey. Analysis and interpretation of data: Raslan, Liu. Drafting the article: Raslan. Critically revising the article: all authors. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Delashaw. Study supervision: Delashaw. Acknowledgments The authors thank Shirley McCartney, Ph.D., for contributions to and preparation of this manuscript and Andy Rekito, M.S., for medical illustrations and figure preparation. References 1. Briggs RJ, Luxford WM, Atkins JS Jr, Hitselberger WE: Translabyrinthine removal of large acoustic neuromas. Neurosurgery 34: , Comey CH, Jannetta PJ, Sheptak PE, Joh HD, Burkhart LE: Staged removal of acoustic tumors: techniques and lessons learned from a series of 83 patients. Neurosurgery 37: , Committee on Hearing and Equilibrium: Committee on Hearing and Equilibrium guidelines for the evaluation of hearing preservation in acoustic neuroma (vestibular schwannoma). American Academy of Otolaryngology-Head and Neck Surgery Foundation, INC. Otolaryngol Head Neck Surg 113: , Godefroy WP, van der Mey AG, de Bruine FT, Hoekstra ER, Malessy MJ: Surgery for large vestibular schwannoma: residual tumor and outcome. Otol Neurotol 30: , Iwai Y, Yamanaka K, Ishiguro T: Surgery combined with radio J Neurosurg / Volume 116 / May 2012

8 Staged resection of large vestibular schwannomas surgery of large acoustic neuromas. Surg Neurol 59: , Kaylie DM, Gilbert E, Horgan MA, Delashaw JB, McMenomey SO: Acoustic neuroma surgery outcomes. Otol Neurotol 22: , Lanman TH, Brackmann DE, Hitselberger WE, Subin B: Report of 190 consecutive cases of large acoustic tumors (vestibular schwannoma) removed via the translabyrinthine approach. J Neurosurg 90: , Mamikoglu B, Wiet RJ, Esquivel CR: Translabyrinthine approach for the management of large and giant vestibular schwannomas. Otol Neurotol 23: , Myrseth E, Møller P, Pedersen PH, Vassbotn FS, Wentzel- Larsen T, Lund-Johansen M: Vestibular schwannomas: clinical results and quality of life after microsurgery or gamma knife radiosurgery. Neurosurgery 56: , Naguib MB, Saleh E, Cokkeser Y, Aristegui M, Landolfi M, Taibah AK, et al: The enlarged translabyrinthine approach for removal of large vestibular schwannomas. J Laryngol Otol 108: , Nicoucar K, Momjian S, Vader JP, De Tribolet N: Surgery for large vestibular schwannomas: how patients and surgeons perceive quality of life. J Neurosurg 105: , Patni AH, Kartush JM: Staged resection of large acoustic neuromas. Otolaryngol Head Neck Surg 132:11 19, Rigby PL, Shah SB, Jackler RK, Chung JH, Cooke DD: Acoustic neuroma surgery: outcome analysis of patient-perceived disability. Am J Otol 18: , Samii M, Gerganov VM, Samii A: Functional outcome after complete surgical removal of giant vestibular schwannomas. Clinical article. J Neurosurg 112: , Sluyter S, Graamans K, Tulleken CA, Van Veelen CW: Analysis of the results obtained in 120 patients with large acoustic neuromas surgically treated via the translabyrinthine-transtentorial approach. J Neurosurg 94:61 66, Wu H, Sterkers J: Translabyrinthine removal of large acoustic neuromas in young adults. Auris Nasus Larynx 27: , Yamakami I, Uchino Y, Kobayashi E, Yamaura A, Oka N: Removal of large acoustic neurinomas (vestibular schwannomas) by the retrosigmoid approach with no mortality and minimal morbidity. J Neurol Neurosurg Psychiatry 75: , 2004 Manuscript submitted August 18, Accepted January 23, Please include this information when citing this paper: published online February 24, 2012; DOI: / JNS Address correspondence to: Johnny B. Delashaw Jr., M.D., Department of Neurological Surgery, Oregon Health & Science University, 3303 SW Bond Avenue, Portland, Oregon delashaw@ohsu.edu. J Neurosurg / Volume 116 / May