Near total extirpation of vestibular schwannoma with salvage radiosurgery

Outcomes of Near-Total and Subtotal Resection of Sporadic Vestibular Schwannoma: A Systematic Review and Meta-Analysis

OBJECTIVE

To evaluate tumor control and facial nerve outcomes after gross-total (GTR), near-total (NTR), and subtotal resection (STR) of sporadic vestibular schwannomas (VS).

DATA SOURCES

PubMed, Cochrane Central Register of Controlled Trials, Web of Science, and Scopus databases were searched in August 2021 through inception following PRISMA guidelines.

REVIEW METHODS

English language articles reporting tumor control and facial nerve outcomes of adults (≥18 years) with NTR and STR of VS were evaluated. Study characteristics, demographics data, tumor characteristics, type of surgical intervention, and outcome measures on tumor control and facial nerve function were collected. Pooled relative risk (RR) estimates for tumor recurrence and facial nerve outcomes were calculated and stratified by extent of resection.

RESULTS

From an initial search of 2504 articles, 48 studies were included in the analysis. When comparing 1108 patients who underwent NTR to 3349 patients with GTR, the pooled RR of recurrence in the NTR cohort was 2.94 (95% confidence interval [CI] 1.65-5.24, P = .0002). When comparing 1016 patients who underwent STR to 6171 patients with GTR, the pooled RR of recurrence in the STR cohort was 11.50 (95% CI 6.64-19.92, P < .0001). Estimates for risk of tumor regrowth for less-than-complete resection are presented. There was no elevated risk of adverse facial nerve outcome (defined as House-Brackmann grade III and above) in each category of extent of resection compared to GTR.

CONCLUSION

Extent of resection predicts risk of tumor recurrence/regrowth following microsurgical resection. Favorable facial nerve outcome should be weighed against the increased risk of regrowth and the potential need for further treatment.

Salvage radiosurgery following subtotal resection of vestibular schwannomas: does timing influence tumor control?

OBJECTIVE

The goal of microsurgical resection of vestibular schwannoma (VS) is gross-total resection (GTR) to provide oncological cure. However, a popular strategy is to halt the resection if the surgical team feels the risk of cranial nerve injury is imminent, achieving a maximally safe subtotal resection (STR) instead. The tumor remnant can then be treated with stereotactic radiosurgery (SRS) once the patient has recovered from the immediate postoperative period, or it can be followed with serial imaging and treated with SRS in a delayed fashion if residual tumor growth is seen. In this study, the authors evaluated the efficacy of this multimodality approach, particularly the influence of timing and dose of SRS on radiological tumor control, need for salvage treatment, and cranial nerve function.

METHODS

VS patients treated with initial microsurgery and subsequent radiosurgery were retrospectively included from two tertiary treatment centers and dichotomized depending on whether SRS was given upfront (defined as before 12 months) or later. Radiological tumor control was defined as less than 20% tumor volume expansion and oncological tumor control as an absence of salvage treatment. Facial and cochlear nerve functions were assessed after surgery, at the time of SRS, and at last follow-up. Finally, a systematic literature review was conducted according to PRISMA guidelines.

RESULTS

A total of 110 VS patients underwent SRS following microsurgical resection, with a mean preradiosurgical tumor volume of 2.2 cm3 (SD 2.5 cm3) and mean post-SRS follow-up time of 5.8 years (SD 4.1 years). The overall radiological tumor control and oncological tumor control were 77.3% and 90.9%, respectively. Thirty-five patients (31.8%) received upfront SRS, while 75 patients (68.2%) were observed for a minimum of 12 months prior to SRS. The timing of SRS did not influence the radiological tumor control (p = 0.869), the oncological tumor control (p = 0.560), or facial nerve (p = 0.413) or cochlear nerve (p = 0.954) function. An escalated marginal dose (> 12 Gy) was associated with greater tumor shrinkage (p = 0.020) and superior radiological tumor control (p = 0.020), but it did not influence the risk of salvage treatment (p = 0.904) or facial (p = 0.351) or cochlear (p = 0.601) nerve deterioration.

CONCLUSIONS

Delayed SRS after close observation of residuals following STR is a safe alternative to upfront SRS regarding tumor control and cranial nerve preservation in selected patients.

Factors Influencing Personalized Management of Vestibular Schwannoma: A Systematic Review

Management of vestibular schwannoma (VS) is a complex process aimed at identifying a clinical indication for fractionated stereotactic radiotherapy (sRT) or microsurgical resection or wait and scan (WS). The aim of the review was to clarify which patient and tumor parameters may lead to different therapeutic choices, with a view to a personalized VS approach. A systematic review according to Preferred Reporting Items for Systematic Review and Meta-Analysis criteria was conducted between February and March 2022. The authors defined six parameters that seemed to influence decision-making in VS management: 1-incidental VS; 2-tumor size; 3-tumor regrowth after sRT; 4-subtotal resection; 5-patients' age; 6-symptoms. The initial search yielded 3532 articles, and finally, 812 articles were included. Through a qualitative synthesis of the included studies, management strategies were evaluated and discussed. An individualized proposal of procedures is preferable as compared to a single gold-standard approach in VS decision-making. The most significant factors that need to be considered when dealing with a VS diagnosis are age, tumor size and hearing preservation issues.

Predictors of Recurrence After Sub-total or Near-total Resection of Vestibular Schwannoma: Importance of Tumor Volume and Ventral Extension

OBJECTIVE

To evaluate the predictors of remnant tumor regrowth and need for salvage therapy after less than gross total resection (GTR) of vestibular schwannoma (VS).

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary neurotologic referral center.

PATIENTS

Patients who underwent VS resection between 2008 and 2019 either with GTR, near total resection (NTR), and subtotal resection (STR).

INTERVENTIONS

Microsurgical resection, salvage radiosurgery.

MAIN OUTCOME MEASURES

Regrowth free interval, salvage free interval, tumor doubling rate.

RESULTS

Three hundred eighty five cases (GTR = 236, NTR = 77, and STR = 71) from 2008 to 2019 were included. STR cohort had much larger and complex tumors with significant differences in tumor volume, ventral extension and brainstem compression (p  < 0.001). On single predictor analysis, tumor volume, ventral extension, brainstem compression as well as STR strategy was associated with significant increased risk of regrowth and need for salvage therapy. Multivariate analysis revealed STR strategy as significant predictor of regrowth (hazard ratio 3.79, p  < 0.0005). Absolute remnant volume and extent of resection (EOR) did not predict regrowth. A small proportion of cases (NTR = 4%, STR = 15%) eventually needed salvage radiosurgery with excellent ultimate local tumor control with no known recurrence to date.

CONCLUSIONS

Conservative surgical strategy employing NTR or STR can be employed safely in large and complex VS. While there is increased risk of regrowth in the STR cohort, excellent local control can be achieved with appropriate use of salvage radiosurgery. No disceret radiologic or operative predictors of regrowth were identified.

Clinical Studies and Pre-clinical Animal Models on Facial Nerve Preservation, Reconstruction, and Regeneration Following Cerebellopontine Angle Tumor Surgery-A Systematic Review and Future Perspectives

Background and purpose: Tumorous lesions developing in the cerebellopontine angle (CPA) get into close contact with the 1st (cisternal) and 2nd (meatal) intra-arachnoidal portion of the facial nerve (FN). When surgical damage occurs, commonly known reconstruction strategies are often associated with poor functional recovery. This article aims to provide a systematic overview for translational research by establishing the current evidence on available clinical studies and experimental models reporting on intracranial FN injury.

Methods: A systematic literature search of several databases (PubMed, EMBASE, Medline) was performed prior to July 2020. Suitable articles were selected based on predefined eligibility criteria following the Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) guidelines. Included clinical studies were reviewed and categorized according to the pathology and surgical resection strategy, and experimental studies according to the animal. For anatomical study purposes, perfusion-fixed adult New Zealand white rabbits were used for radiological high-resolution imaging and anatomical dissection of the CPA and periotic skull base.

Results: One hundred forty four out of 166 included publications were clinical studies reporting on FN outcomes after CPA-tumor surgery in 19,136 patients. During CPA-tumor surgery, the specific vulnerability of the intracranial FN to stretching and compression more likely leads to neurapraxia or axonotmesis than neurotmesis. Severe FN palsy was reported in 7 to 15 % after vestibular schwannoma surgery, and 6% following the resection of CPA-meningioma. Twenty-two papers reported on experimental studies, out of which only 6 specifically used intracranial FN injury in a rodent (n = 4) or non-rodent model (n = 2). Rats and rabbits offer a feasible model for manipulation of the FN in the CPA, the latter was further confirmed in our study covering the radiological and anatomical analysis of perfusion fixed periotic bones.

Conclusion: The particular anatomical and physiological features of the intracranial FN warrant a distinguishment of experimental models for intracranial FN injuries. New Zealand White rabbits might be a very cost-effective and valuable option to test new experimental approaches for intracranial FN regeneration. Flexible and bioactive biomaterials, commonly used in skull base surgery, endowed with trophic and topographical functions, should address the specific needs of intracranial FN injuries.

Clinical Predictors of Facial Nerve Outcomes After Surgical Resection of Vestibular Schwannoma

OBJECTIVE

To identify clinical predictors of facial nerve (FN) outcomes after microsurgical resection of vestibular schwannoma (VS).

STUDY DESIGN

Prospective cohort study.

SETTING

Academic medical center.

METHODS

Consecutive patients undergoing VS resection from November 2017 to October 2019 were included. FN function was evaluated with the House-Brackmann (HB) scale and stratified into good (HB I-II) and poor (HB III-VI) function. Analyses included descriptive statistics, correlation, and logistic regression.

RESULTS

Of 256 patients who met criteria (mean age, 47.7 years; 62.5% female), 227 (88.7%) achieved good FN function postoperatively and 238 (93.0%) at latest follow-up (mean, 154.8 days). Operative approaches consisted of translabyrinthine (50.8%), retrosigmoid (25.0%), and middle fossa craniotomies (24.2%). Extent of resection was decided intraoperatively, and gross or near total resection was accomplished in 237 (92.6%) cases. Postoperative HB grade correlated with latest HB grade (0.615, P < .001). Factors associated with good postoperative FN function included small tumor size (≤15 mm; odds ratio [OR], 2.425; P = .042), gross or near total resection (OR, 3.170; P = .041), and ≥100-µV intraoperative FN electromyographic response to a 0.05-mA stimulus (OR, 22.242; P < .001). Factors associated with good FN function at latest follow-up included gross total resection (OR, 7.764; P = .003) and ≥100-µV FN electromyographic response (OR, 8.518; P < .001), accounting for surgical approach and tumor size.

CONCLUSION

Microsurgical resection of VS can be accomplished with excellent FN outcomes. Gross total resection and ≥100-µV intraoperative FN electromyographic response predicted excellent FN outcomes. Immediate postoperative FN function is a prognosticator of long-term FN function.

The impact of the MIB-1 index on facial nerve outcomes in vestibular schwannoma surgery

Background

Facial nerve palsy is a severe morbid condition that occurs after vestibular schwannoma (VS) surgery. The objective of this study was to evaluate facial nerve outcomes based on surgical techniques, tumour size, and immunohistochemical factors.

Methods

One hundred eighteen patients with VS were retrospectively analysed. Gross total resection (GTR) was achieved in 83 patients, and subtotal resection (STR) was achieved in 35 patients. Follow-up was 60 months (median). Facial nerve outcomes were assessed for 24 months after surgery. Analysis of the MIB-1 index was performed in 114 patients (97%) to evaluate recurrence and facial nerve outcomes.

Results

Immediately after surgery, 16 of 35 patients (45.7%) with STR and 21 of 83 patients (25.3%) with GTR had a good (House-Brackmann (HB) score ≤ 2) facial nerve outcome (p = 0.029). Semi-sitting positioning (p = 0.002) and tumour size class of 3 (> 4 cm) were also associated with worse HB outcomes after 2 years (p = 0.004) in univariate analyses. The MIB-1 index was significantly correlated with diffuse infiltration of tumour-associated CD45⁺ lymphocytes (r = 0.63, p = 0.015) and CD68⁺ macrophages (r = 0.43, p = 0.021). ROC analysis found an AUC of 0.73 (95% CI = 0.60–0.86, p = 0.003) for the MIB-1 index in predicting poor facial nerve outcomes. Binary logistic regression analysis revealed an MIB-1 index ≥ 5% (16/28 (57.1%) vs. 5/40 (12.5%); p < 0.001, OR = 14.0, 95% CI = 3.2–61.1) and a tumour size class of 3 (6/8 (75.0%) vs. 2/8 (25.0%); p = 0.01, OR = 14.56, 95% CI = 1.9–113.4) were predictors of poor HB scores (≥ 3) after 1 year.

Conclusions

An MIB-1 index ≥ 5% seems to predict worse long-term facial nerve outcomes in VS surgery.

EAONO position statement on Vestibular Schwannoma: Imaging Assessment Question: How should growth of Vestibular Schwannoma be defined?

The relevance of defining the growth of vestibular schwannoma (VS) is that any significant VS growth may impact treatment strategy. A conservative treatment strategy is often proposed as a primary treatment option in the management of VS. Several authors have demonstrated that a significant proportion of VSs do not grow, and those that do, usually grow slowly. Surgical and/or radiosurgical treatment options may be offered to the patient according to the VS growth. Therefore, defining the VS growth is a determinant in managing treatment strategies. A comprehensive literature search was performed to examine the definition of tumor growth for VS. The literature review was conducted using PubMed and Embase databases dated back to 20 years (1995-2015) and was updated until February 2015. VS growth should be measured on contrast-enhanced T1-weighted images. Although there the overall quality of the present studies is low, all highlight a significant VS growth of > 2 mm, and/or 1.2 cm3, and/or 20% change in volume, and/or the square of the product of the 2 orthogonal diameters. We suggest that VS growth should instead change management strategies when a 3-mm increase in diameter on two consecutive MRI scans are performed 1 year apart.

Intended Near-Total Removal of Koos Grade IV Vestibular Schwannomas: Reconsidering the Treatment Paradigm

BACKGROUND

The goals of treating Koos grade IV vestibular schwannomas are to relieve brainstem compression, preserve or restore neurological function, and achieve long-term tumor control while minimizing tumor- and treatment-related morbidity.

OBJECTIVE

To propose a treatment paradigm involving the intentional near-total removal of Koos grade IV vestibular schwannomas, in which a small amount of residual tumor is not dissected off the cisternal portion of the facial nerve. Patients are then followed by a wait-and-scan approach. Any subsequent volumetric progression of the residual tumor is treated with radiosurgery.

METHODS

This is a case series of 44 consecutive unselected patients who underwent intended near-total resection of a Koos grade IV vestibular schwannoma through a retrosigmoid approach from January 2009 to December 2015. Pre- and postoperative volumetric analyses were performed on routine magnetic resonance imaging sequences (constructive interference in steady state and gadolinium-enhanced T1-weighted sequence).

RESULTS

The mean preoperative tumor volume was 10.9 cm3. The mean extent of resection was 89%. At the last clinical follow-up, facial nerve function was good [House and Brackmann (HB) I-II] in 89%, fair (HB III) in 9%, and poor (HB IV-VI) in 2% of the patients. At the last radiological follow-up, the residual tumor had become smaller or remained the same size in 84% of patients. Volumetric progression was negatively correlated with the original extent of resection and positively correlated with postoperative residual tumor volume (P = .01, P < .001, respectively).

CONCLUSION

Intended near-total removal results in excellent preservation of facial nerve function and has a low recurrence rate. Any progressive residual tumor may be treated by radiosurgery.

Radiosurgery treatment is associated with improved facial nerve preservation versus repeat resection in recurrent vestibular schwannomas

BACKGROUND

Vestibular schwannomas (VSs) are benign neoplasms of the Schwann cells of cranial nerve VIII, and treatment of VS typically involves surgical resection. However, tumor recurrence may necessitate reintervention, and secondary treatment modalities include repeat surgical resection or adjuvant radiosurgery. The purpose of this study is to examine the scientific literature in order to determine whether surgical resection or radiosurgery for recurrent VS results in better tumor control, hearing preservation, and preservation of facial nerve function.

METHODS

The PubMed, Scopus, Embase, Cochrane, and Web of Science databases were searched for studies reporting on patients undergoing either radiosurgery or repeat surgical resection after primary surgical resection for recurrent VS. Statistical analyses were performed on the compiled data, primarily outcome data involving tumor control, hearing preservation, and preservation of facial nerve function.

RESULTS

We analyzed the data of 15 individual studies involving 359 total patients, and our results reveal that tumor control rates are comparable between adjuvant radiosurgery (91%, CI: 88-94%) and secondary resection (92%, CI 75-98%). However, adjuvant radiosurgery was shown to preserve good facial nerve function better (94%, CI 84-98%) compared to secondary surgical resection (56%, CI 41-69%).

CONCLUSION

With comparable tumor control rates and better preservation of good facial nerve function, this study suggests that secondary radiosurgery for recurrent VS is associated with both optimal tumor control and preservation of good facial nerve function.

Short-Term Surgical Outcome for Vestibular Schwannoma in Sweden: A Nation-Wide Registry Study

Background: Vestibular Schwannoma (VS) is a benign neoplasm arising from the 8th cranial nerve, with surgery one of the treatment modalities. In a nation-wide registry study, we describe the baseline, treatment characteristics, and short-term outcome in patients surgically treated for VS.

Methods: We performed a nationwide study with data from the Swedish Brain Tumor Registry (SBTR) for all adults diagnosed with VS 2009–2015. Patient symptoms, tumor characteristics, and postoperative complications were analyzed.

Results: In total 348 patients underwent surgery for VS. Mean age was 50.6 ± 14.5 years and 165 patients (47.4%) were female. The most common symptom was focal neurological deficit (92.0%), with only 25 (7.2%) being asymptomatic prior to surgery, and 217 (63.6%) had no restriction in activity. Following surgery, 100 (28.7%) patients developed new deficit(s). In terms of postoperative complications; 11 (3.2%) had a hematoma, 35 (10.1%) an infection, 10 (2.9%) a venous thromboembolism, and 23 (6.6%) had a reoperation due to complication. There were no deaths within 30-days after surgery. When grouped according to tumor size (< 4 vs. ≥4 cm), those with ≥4 cm tumors were more often males (p = 0.02), had more often ICP related symptoms (p = 0.03) and shorter time from imaging to surgery (p < 0.01). Analysis of the younger (< 65 years) vs. elderly (≥65 years) revealed no difference in outcome except increased 1-year mortality (p = 0.002) in elderly.

Conclusion: In this nation-wide registry-study, we benchmark the 30-day complication rate after VS surgery as collected by the SBTR. Further, we present the current neurosurgical outcome data from both VS smaller than 40 mm compared to larger tumors, as well as younger vs. elderly VS patients. Since surgical decision making is a careful consideration of short term risk vs. long term benefit, this information can be useful in clinical decision making.

Adaptive Hybrid Surgery: Paradigm Shift for Patient-centered Neurosurgery

The surgical management of cerebral and skull base lesions has evolved greatly in the last few decades. Still, a complete resection of lesions abutting critical neurovascular structures carries significant morbidity. Stereotactic radiosurgery (SRS) has emerged as an increasingly accepted treatment option. Minimally invasive, SRS results in excellent tumor control and low complication rates in patients with moderate-size tumors. The management of large cerebral and skull base tumors remains a formidable challenge. In such large tumors, radical surgical extirpation offers a significantly higher risk of neurological deficit, and SRS alone cannot be used because of the elevated incidence of radiation-induced complications known to be associated with large-volume tumors. With increasing treatment volumes, SRS-associated tumor control rates decrease and complication rates increase. Planned subtotal resection (STR) with adjuvant SRS (adaptive hybrid surgery [AHS]) has gained increasing interest in recent years as a multimodal approach. In AHS, a planned STR (aimed at decreasing surgical morbidity) followed by SRS to a preplanned residual tumor aids in harnessing advantages offered by both approaches. Although intuitive and reasonable, this paradigm shift from maximal resection at all cost has not been adopted widely. Combining open microsurgery with SRS requires a good understanding of both surgical and SRS modalities and their respective safety-efficacy features. We present a review and discussion on AHS as a modern, multidisciplinary treatment approach. Available data and views are discussed for vestibular schwannoma (VS) as a sample tumor. Other indications for AHS are mentioned in brief.

[Facial nerve injury in neurosurgery: a rehabilitation potential of botulinum therapy]

Surgical treatment of posterior cranial fossa and cerebellopontine angle tumors is associated with a risk of facial nerve dysfunction. The causes for facial muscle paresis include nerve compression by the tumor, destruction of the nerve structure by the tumor growing from nerve fibers, nerve injury during surgical removal of the tumor, etc. The first 3 months after facial nerve injury are a potential therapeutic window for the use of botulinum toxin type A (BTA). During this period, the drug is introduced both in the healthy side to improve the facial symmetry at rest and during mimetic movements and in the affected side to induce drug-induced ptosis. Post-paralytic syndrome develops 4-6 months after facial nerve injury. At this stage, administration of BTA is also an effective procedure; in this case, drug injections are performed on the affected side at small doses and symmetrically on the healthy side at doses doubling those for the affected side. BTA injections are mandatory in complex treatment of facial muscle paralysis.

Facial Nerve Outcome and Tumor Control Rate as a Function of Degree of Resection in Treatment of Large Acoustic Neuromas: Preliminary Report of the Acoustic Neuroma Subtotal Resection Study (ANSRS)

BACKGROUND

Patients with large vestibular schwannomas are at high risk of poor facial nerve (cranial nerve VII [CNVII]) function after surgery. Subtotal resection potentially offers better outcome, but may lead to higher tumor regrowth.

OBJECTIVE

To assess long-term CNVII function and tumor regrowth in patients with large vestibular schwannomas.

METHODS

Prospective multicenter nonrandomized cohort study of patients with vestibular schwannoma ≥2.5 cm who received gross total resection, near total resection, or subtotal resection. Patients received radiation if tumor remnant showed signs of regrowth.

RESULTS

Seventy-three patients had adequate follow-up with mean tumor diameter of 3.33 cm. Twelve received gross total resection, 22 near total resection, and 39 subtotal resection. Fourteen (21%) remnant tumors continued to grow, of which 11 received radiation, 1 had repeat surgery, and 2 no treatment. Four of the postradiation remnants (36%) required surgical salvage. Tumor regrowth was related to non-cystic nature, larger residual tumor, and subtotal resection. Regrowth was 3 times as likely with subtotal resection compared to gross total resection and near total resection. Good CNVII function was achieved in 67% immediately and 81% at 1-year. Better immediate nerve function was associated with smaller preoperative tumor size and percentage of tumor left behind on magnetic resonance image. Degree of resection defined by surgeon and preoperative tumor size showed weak trend toward better late CNVII function.

CONCLUSION

Likelihood of tumor regrowth was 3 times higher in subtotal resection compared to gross total resection and near total resection groups. Rate of radiation control of growing remnants was suboptimal. Better immediate but not late CNVII outcome was associated with smaller tumors and larger tumor remnants.

ABBREVIATIONS

CNVII, cranial nerve VIIGTR, gross total resectionHB, House-BrackmannMRI, magnetic resonance imageNTR, near total resectionSTR, subtotal resection.

Preserving normal facial nerve function and improving hearing outcome in large vestibular schwannomas with a combined approach: planned subtotal resection followed by gamma knife radiosurgery

Objective

To perform planned subtotal resection followed by gamma knife surgery (GKRS) in a series of patients with large vestibular schwannoma (VS), aiming at an optimal functional outcome for facial and cochlear nerves.

Methods

Patient characteristics, surgical and dosimetric features, and outcome were collected prospectively at the time of treatment and during the follow-up.

Results

A consecutive series of 32 patients was treated between July 2010 and June 2016. Mean follow-up after surgery was 29 months (median 24, range 4–78). Mean presurgical tumor volume was 12.5 cm³ (range 1.47–34.9). Postoperative status showed normal facial nerve function (House–Brackmann I) in all patients. In a subgroup of 17 patients with serviceable hearing before surgery and in which cochlear nerve preservation was attempted at surgery, 16 (94.1%) retained serviceable hearing. Among them, 13 had normal hearing (Gardner–Robertson class 1) before surgery, and 10 (76.9%) retained normal hearing after surgery. Mean duration between surgery and GKRS was 6.3 months (range 3.8–13.9). Mean tumor volume at GKRS was 3.5 cm³ (range 0.5–12.8), corresponding to mean residual volume of 29.4% (range 6–46.7) of the preoperative volume. Mean marginal dose was 12 Gy (range 11–12). Mean follow-up after GKRS was 24 months (range 3–60). Following GKRS, there were no new neurological deficits, with facial and hearing functions remaining identical to those after surgery in all patients. Three patients presented with continuous growth after GKRS, were considered failures, and benefited from the same combined approach a second time.

Conclusion

Our data suggest that large VS management, with planned subtotal resection followed by GKRS, might yield an excellent clinical outcome, allowing the normal facial nerve and a high level of cochlear nerve functions to be retained. Our functional results with this approach in large VS are comparable with those obtained with GKRS alone in small- and medium-sized VS. Longer term follow-up is necessary to fully evaluate this approach, especially regarding tumor control.

Multivariate Analysis of Factors Influencing Facial Nerve Outcome following Microsurgical Resection of Vestibular Schwannoma

Objective To assess through multivariate analysis the clinical pre- and intraoperative factors of facial nerve outcomes at day 8 and 1-year recovery of facial palsy, as compared with day 8 status among patients who underwent total resection of unilateral vestibular schwannoma. Study Design Case series with chart review. Setting Tertiary referral center. Subjects and Methods This study included 229 patients with preoperative normal facial function and anatomic preservation of the facial nerve. Clinical, radiologic, and intraoperative factors were assessed according to facial nerve function at day 8 and 1 year. Results We observed that 74% and 84% of patients had good facial function (House-Brackmann [HB] I-II) at day 8 and 1 year, respectively. Of 60 patients, 26 (43%) who had impaired facial function (HB III-VI) at day 8 recovered good facial function (HB I-II) 1 year after surgery. A structured equation model showed that advanced tumor stage and strong facial nerve adhesion were independently associated with facial nerve conduction block at day 8. No predictive factor of impaired facial function recovery was seen at 1 year. In terms of the extracanalicular diameter of the tumor, the cutoff point to minimize the risk of impaired facial function was 16 mm. Conclusion At day 8 after vestibular schwannoma resection, facial function was impaired in the case of large tumors or strong facial nerve adhesion to the tumor. After 1 year, less than half of the patients recovered good facial function, and no predictive factor was found to be associated with this possible recovery.

Surgical Treatment of Giant Vestibular Schwannomas: Facial Nerve Outcome and Tumor Control

BACKGROUND

Surgical treatment of giant vestibular schwannomas (GVS) is challenging. The philosophy of incomplete tumor resection may balance the preservation of facial nerve function and long-term tumor control.

OBJECTIVE

We aimed to evaluate the outcome of facial nerve function and tumor control in treating GVS via our institutional surgical strategy.

METHODS

From September 2009 to August 2014, 218 patients who underwent surgical treatment of GVS were enrolled in our study. The clinical features, extent of resections, facial nerve outcome, and the tumor regrowth free rate of these patients were retrospectively analyzed. The treatment strategy of this disease was discussed.

RESULTS

All patients had anatomic preservation of the facial nerve. Gross total resection (GTR) was achieved in 58 patients (28.6%), near-total resection (NTR) in 103 (50.7%), and subtotal resection (STR) in 42 (20.7%). Two patients died because of postoperative complications. After a mean follow-up of 39.7 ± 18.3 months, a favorable facial nerve outcome was achieved in 58.6%, 79.6%, and 83.3% of patients who underwent GTR, NTR, and STR, respectively. During follow-up, 20 patients had tumor regrowth and were treated by stereotactic radiosurgery (SRS), and tumor regrowth free rates were 96.6%, 92.2%, and 76.2% in GTR, NTR, and STR, respectively. The extent of resection was the independent risk factor for poor facial nerve function (P = 0.006).

CONCLUSIONS

A surgical philosophy of prioritizing facial nerve preservation over total tumor resection was recommended in treatment of GVS. Favorable facial nerve outcome and tumor control were achieved after NTR of the tumors.