Predictive factors of long-term facial nerve function after vestibular schwannoma surgery

Incidence and Risk Factors of Delayed Facial Paralysis After Vestibular Schwannoma Resection: A Systematic Review and Meta-Analysis

OBJECTIVE

Delayed facial nerve paralysis (DFNP) is a common complication after vestibular schwannoma surgery. Previous studies have focused on immediate facial nerve paralysis, and the risk factors for developing DFNP remain largely unclear. This study aimed to determine the incidence and risk factors of DFNP in patients after vestibular schwannoma resection.

METHODS

Up to 8 October 2024, PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure, Wanfang Data, and China Science and Technology Journal Database were searched to extract the related data of DFNP. The pooled incidence of DFNP was calculated. Possible risk factors of DFNP were conducted to report the odds ratio/weighted mean difference (WMD), and their 95% confidence intervals (CIs).

RESULTS

Twenty-seven studies were included, and 8656 patients underwent vestibular schwannoma resection. The incidence of DFNP in patients with vestibular schwannoma who underwent microsurgical resection was 12.3% (95% CI: 9.4%, 15.1%). The results of the influencing factor analysis showed that age (WMD: -4.28, 95% CI: -5.66, -2.91) and tumor size (WMD: 0.17, 95% CI: 0.01, 0.22) were related to the incidence of DFNP in patients after vestibular schwannoma resection.

CONCLUSIONS

DFNP is a complication after vestibular schwannoma surgery that cannot be ignored. The risk factors (age and tumor size) of DFNP in patients after vestibular schwannoma surgery still need to be considered, and clinical management of high-risk groups should be strengthened in clinical practice.

Development and application of explainable artificial intelligence using machine learning classification for long-term facial nerve function after vestibular schwannoma surgery

PURPOSE

Vestibular schwannomas (VSs) represent the most common cerebellopontine angle tumors, posing a challenge in preserving facial nerve (FN) function during surgery. We employed the Extreme Gradient Boosting machine learning classifier to predict long-term FN outcomes (classified as House-Brackmann grades 1-2 for good outcomes and 3-6 for bad outcomes) after VS surgery.

METHODS

In a retrospective analysis of 256 patients, comprehensive pre-, intra-, and post-operative factors were examined. We applied the machine learning (ML) classifier Extreme Gradient Boosting (XGBoost) for the following binary classification: long-term good and bad FN outcome after VS surgery To enhance the interpretability of our model, we utilized an explainable artificial intelligence approach.

RESULTS

Short-term FN function (tau = 0.6) correlated with long-term FN function. The model exhibited an average accuracy of 0.83, a ROC AUC score of 0.91, and Matthew's correlation coefficient score of 0.62. The most influential feature, identified through SHapley Additive exPlanations (SHAP), was short-term FN function. Conversely, large tumor volume and absence of preoperative auditory brainstem responses were associated with unfavorable outcomes.

CONCLUSIONS

We introduce an effective ML model for classifying long-term FN outcomes following VS surgery. Short-term FN function was identified as the key predictor of long-term function. This model's excellent ability to differentiate bad and good outcomes makes it useful for evaluating patients and providing recommendations regarding FN dysfunction management.

A multi-institutional machine learning algorithm for prognosticating facial nerve injury following microsurgical resection of vestibular schwannoma

Vestibular schwannomas (VS) are the most common tumor of the skull base with available treatment options that carry a risk of iatrogenic injury to the facial nerve, which can significantly impact patients' quality of life. As facial nerve outcomes remain challenging to prognosticate, we endeavored to utilize machine learning to decipher predictive factors relevant to facial nerve outcomes following microsurgical resection of VS. A database of patient-, tumor- and surgery-specific features was constructed via retrospective chart review of 242 consecutive patients who underwent microsurgical resection of VS over a 7-year study period. This database was then used to train non-linear supervised machine learning classifiers to predict facial nerve preservation, defined as House-Brackmann (HB) I vs. facial nerve injury, defined as HB II-VI, as determined at 6-month outpatient follow-up. A random forest algorithm demonstrated 90.5% accuracy, 90% sensitivity and 90% specificity in facial nerve injury prognostication. A random variable (rv) was generated by randomly sampling a Gaussian distribution and used as a benchmark to compare the predictiveness of other features. This analysis revealed age, body mass index (BMI), case length and the tumor dimension representing tumor growth towards the brainstem as prognosticators of facial nerve injury. When validated via prospective assessment of facial nerve injury risk, this model demonstrated 84% accuracy. Here, we describe the development of a machine learning algorithm to predict the likelihood of facial nerve injury following microsurgical resection of VS. In addition to serving as a clinically applicable tool, this highlights the potential of machine learning to reveal non-linear relationships between variables which may have clinical value in prognostication of outcomes for high-risk surgical procedures.

[Utility of the intraoperative neurophysiological monitoring as a prognostic value of postoperative facial paresis in vestibular schwannomas]

BACKGROUND AND OBJECTIVE

Intraoperative neurophysiological monitoring allows us to predict the functional status of the facial nerve after vestibular schwannoma surgery. Due to the great variability of the neurophysiological protocols used for it, the goal of this study is to determine the prognostic ability of our neurophysiological protocol.

MATERIAL AND METHODS

We have performed a statistical analysis of the neurophysiological monitoring data collected from patients operated between March 2009 and July 2021 at the Neurosurgery Service of Salamanca according to their functional status, both in the immediate post-surgical period and one year after surgery.

RESULTS

A number of 51 patients between 46 and 63 years old (median: 54) were analyzed. We have found significant differences studying the threshold value of the stimulation intensity of the facial nerve and the variation of the Cortico-bulbar Evoked Motor Potentials (P=0.043 and P=0.011, respectively) between the patients with good and bad clinical situation after surgery. The most discriminating intensity threshold value was 0.35mA (Sensitivity: 85%; Specificity: 48%). No statistical relationship was found in the study group one year after surgery.

CONCLUSIONS

Our intraoperative monitoring protocol allows us to predict the clinical situation of patients in the immediate postoperative period and improve information for the patient and her relatives after surgery. We cannot, however, use these parameters to predict the functional situation one year after surgery and make clinical decisions in this regard.

Facial nerve outcome score: a new score to predict long-term facial nerve function after vestibular schwannoma surgery

Introduction

Patients' quality of life (QoL), facial nerve (FN), and cochlear nerve (CN) (if conserved) functions should be pursued as final outcomes of vestibular schwannoma (VS) surgery. In regard to FN function, different morphologic and neurophysiological factors have been related to postoperative outcomes. The aim of the current retrospective study was to investigate the impact of these factors on the short- and long-term FN function after VS resection. The combination of preoperative and intraoperative factors resulted in designing and validating a multiparametric score to predict short- and long-term FN function.

Methods

A single-center retrospective analysis was performed for patients harboring non-syndromic VS who underwent surgical resection in the period 2015-2020. A minimum follow-up period of 12 months was considered among the inclusion criteria. Morphological tumor characteristics, intraoperative neurophysiological parameters, and postoperative clinical factors, namely, House-Brackmann (HB) scale, were retrieved in the study. A statistical analysis was conducted to investigate any relationships with FN outcome and to assess the reliability of the score.

Results

Seventy-two patients with solitary primary VS were treated in the period of the study. A total of 59.8% of patients showed an HB value < 3 in the immediate postoperative period (T1), reaching to 76.4% at the last follow-up evaluation. A multiparametric score, Facial Nerve Outcome Score (FNOS), was built. The totality of patients with FNOS grade A showed an HB value < 3 at 12 months, decreasing to 70% for those with FNOS grade B, whereas 100% of patients with FNOS grade C showed an HB value ≥ 3. The ordinal logistic regression showed three times increasing probability to see an HB value ≥ 3 at 3-month follow-up for each worsening point in FNOS score [Exp(B), 2,999; p < 0.001] that was even more probable [Exp(B), 5.486; p < 0.001] at 12 months.

Conclusion

The FNOS score resulted to be a reliable score, showing high associations with FN function both at short- and long-term follow-up. Although multicenter studies would be able to increase its reproducibility, it could be used to predict the FN damage after surgery and the potential of restoring its function on the long-term period.

Assessing the Efficacy of Anastomosis between Ansa Cervicalis and Facial Nerve for Patients with Concomitant Facial Palsy and Peripheral Neuropathy

Background: For decades, patients with facial asymmetry have experienced social interaction difficulties, leading them to seek treatment in the hope of restoring facial symmetry and quality of life. Researchers evaluated numerous surgical techniques, but achieving results remains a significant hurdle. Specifically, anastomosis between the ansa cervicalis (AC) and facial nerve (FN) can hinder the patient's physical appearance. Objective: Our study goal was to examine the efficiency of anastomosis between AC and FN for facial motor function recovery even in the presence of peripheral neuropathy. Materials and Methods: Four patients diagnosed with facial palsy grade VI on the House & Brackmann Scale (HB) after vestibular schwannoma (VS) resection (Koos grade IV) via the retrosigmoid approach underwent AC and FN anastomosis. Outcomes were related to tumor grade, previous therapy, and the time between postoperative facial palsy and anastomosis. Images and neurophysiological data were evaluated. Results: After vs. resection, all four patients demonstrated HB grade VI facial palsy for an average of 17 months. During the follow-up program, lasting between 6 and 36 months, two patients were evaluated as having HB grade III facial palsy; the other two patients were diagnosed with grade IV HB facial palsy. None of the patients developed tongue atrophy, speech disorder, or masticatordys function. Conclusions: Anastomosis between the AC and FN is a safe and effective treatment for facial paralysis after cerebellopontine tumor resection. Nerve reanimation may be feasible even for patients with peripheral polyneuropathy. This study also offers a new option for patients with a progression-free status.

Nomogram for Predicting Facial Nerve Outcomes After Surgical Resection of Vestibular Schwannoma

Objective

The facial nerve (FN) outcomes after vestibular schwannoma surgery seriously affect the social psychology and quality of life of patients. More and more attention has been paid to the protection of FN function. This study aimed to identify significant prognostic factors for FN outcomes after vestibular schwannoma surgery and create a new nomogram for predicting the rates of poor FN outcomes.

Methods

Data from patients who had undergone operations for vestibular schwannoma between 2015 and 2020 were retrieved retrospectively and patients were divided into good and poor FN outcomes groups according to postoperative nerve function. The nomogram for predicting the risk of poor FN outcomes was constructed from the results of the univariate logistic regression analysis and the multivariate logistic regression analysis of the influencing factors for FN outcomes after surgical resection of vestibular schwannoma.

Results

A total of 392 participants were enrolled. The univariate logistic regression analysis revealed that age, tumor size, cystic features of tumors, cerebrospinal fluid (CSF) cleft sign, tumor adhesion to the nerve, learning curve, and FN position were statistically significant. The multivariate logistic regression analysis showed that age, tumor size, cystic features of tumors, CSF cleft sign, tumor adhesion to the nerve, learning curve, and FN position were independent factors. The nomogram model was constructed according to these indicators. At the last follow-up examination, a good FN outcome was observed in 342 patients (87.2%) and only 50 patients (12.8%) was presented with poor FN function. Application of the nomogram in the validation cohort still gave good discrimination [area under the curve (AUC), 0.806 (95% CI, 0.752–0.861)] and good calibration.

Conclusion

This study has presented a reliable and valuable nomogram that can accurately predict the occurrence of poor FN outcomes after surgery in patients. This tool is easy to use and could assist doctors in establishing clinical decision-making for individual patients.

Applicability of contemporary quality indicators in vestibular surgery-do they accurately measure tumor inherent postoperative complications of vestibular schwannomas?

Background

Due to rising costs in health care delivery, reimbursement decisions have progressively been based on quality measures. Such quality indicators have been developed for neurosurgical procedures, collectively. We aimed to evaluate their applicability in patients that underwent surgery for vestibular schwannoma and to identify potential new disease-specific quality indicators.

Methods

One hundred and three patients operated due to vestibular schwannoma were subject to analysis. The primary outcomes of interest were 30-day and 90-day reoperation, readmission, mortality, nosocomial infection and surgical site infection (SSI) rates, postoperative cerebral spinal fluid (CSF) leak, facial, and hearing function. The secondary aim was the identification of prognostic factors for the mentioned primary outcomes.

Results

Thirty-day (90-days) outcomes in terms of reoperation were 10.7% (14.6%), readmission 9.7% (13.6%), mortality 1% (1%), nosocomial infection 5.8%, and SSI 1% (1%). A 30- versus 90-day outcome in terms of CSF leak were 6.8% vs. 10.7%, new facial nerve palsy 16.5% vs. 6.1%. Hearing impairment from serviceable to non-serviceable hearing was 6.8% at both 30- and 90-day outcome. The degree of tumor extension has a significant impact on reoperation (p < 0.001), infection (p = 0.015), postoperative hemorrhage (p < 0.001), and postoperative hearing loss (p = 0.026).

Conclusions

Our data demonstrate the importance of entity-specific quality measurements being applied even after 30 days. We identified the occurrence of a CSF leak within 90 days postoperatively, new persistent facial nerve palsy still present 90 days postoperatively, and persisting postoperative hearing impairment to non-serviceable hearing as potential new quality measurement variables for patients undergoing surgery for vestibular schwannoma.

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.

Predicting Long-Term Facial Nerve Outcomes After Resection of Vestibular Schwannoma

OBJECTIVES

1) Describe the effect of tumor size on facial nerve (FN) outcomes after microsurgical resection of vestibular schwannoma (VS).2) Describe the effect of surgical approach, preoperative radiation, and early postoperative facial function on long-term FN outcomes.

STUDY DESIGN

Retrospective analysis.

SETTING

Tertiary referral center.

PATIENTS

Adult (≥18 yr) patients underwent translabyrinthine or retrosigmoid VS resection by a single neurotologist and single neurosurgeon between February 2008 and December 2017.

MAIN OUTCOME MEASURES

Long-term FN outcomes (≥12 mo) according to House-Brackmann (HB) grade.

RESULTS

During the study period, 350 patients underwent VS resection, of whom 290 met inclusion criteria. Translabyrinthine surgery was performed in 54% (n = 158) and retrosigmoid in 45% (n = 131). One patient underwent a combined approach. Among patients who underwent retrosigmoid approach, none had a tumor more than 30 mm. Gross total resection was achieved in 98% (n = 283). Long-term HB1-2 function was achieved in 90% (n = 261). On univariate analysis, tumor size (per cm increase), history of preoperative radiation, and worse HB score at discharge predicted worse FN function. Multivariate analysis showed that tumor size (per cm increase) and history of radiation were independent predictors of FN function. For patients with tumors less than 30 mm, multivariate analysis of tumor size and surgical approach was performed; tumor size remained predictive of worse FN function (odds ratio [OR] 2.362, p = 0.0035), whereas surgical approach was not significantly predictive (p = 0.7569).

CONCLUSION

Tumor size and history of radiation predict long-term FN function after VS resection. When accounting for tumor size, the translabyrinthine and retrosigmoid approaches yield equivalent FN results.

Facial Nerve Length Influence on Vestibular Schwannoma Microsurgery Outcomes

OBJECTIVE

Facial nerve (FN) function preservation is the primary goal during vestibular schwannoma (VS) resection. Many factors are linked to postoperative FN outcomes. In the present study, we evaluated the association between FN length and VS surgical outcomes.

METHODS

We included 70 consecutive patients who had undergone VS microsurgery between October 2019 and November 2020. The clinical data were prospectively obtained from the patients. The relative FN (rFN) length was obtained by subtracting the contralateral FN length from the ipsilateral FN length as measured using DSI Studio software (available at: http://dsi-studio.labsolver.org/).

RESULTS

The postoperative FN function was House-Brackmann grade I in 47 of the 70 patients (67.1%), grade II in 10 (14.3%), and grade III in 13 (18.6%). Gross total resection (GTR) was performed in 61 patients (87.1%). A residual tumor was retained to preserve FN function in 9 of the 70 patients (12.9%), and rFN length was measured (mean diameter, 20.8 mm; range, 2.5-51.5]). On multivariate analysis, the rFN length was significantly associated with the extent of tumor resection. The receiver operating characteristic curve indicated that the cutoff value for rFN length to predict for intraoperative near total resection versus GTR was 36.6 mm, with a specificity and sensitivity of 93.4% and 88.9%, respectively.

CONCLUSIONS

The rFN length is important for predicting surgical outcomes. An rFN length >36.6 mm might indicate difficulty in achieving GTR with preservation of FN function. Therefore, the rFN length could become an objective indicator for neurosurgeons to predict the difficulty of GTR to preserve FN function.

Prognostic Factors for the Outcome of Translabyrinthine Surgery for Vestibular Schwannomas

OBJECTIVE

To identify predictors of tumor recurrence and postoperative facial nerve function after translabyrinthine surgery for unilateral vestibular schwannomas.

STUDY DESIGN

Retrospective study.

SETTING

Tertiary referral center.

PATIENTS

Between 1996 and 2017 a total of 596 patients with unilateral vestibular schwannoma underwent translabyrinthine surgery. Pre- and postoperative clinical status, radiological, and surgical findings were evaluated.

INTERVENTIONS

Translabyrinthine surgery.

MAIN OUTCOME MEASURES

Potential predictors for tumor recurrence and facial nerve outcome were analyzed using Cox regression and ordinal logistic regression, respectively.

RESULTS

The extent of tumor removal was total in 32%, near-total in 58%, and subtotal in 10%. In 5.5% (33/596) of patients the tumor recurred. Subtotal tumor resection (p = 0.004, hazard ratios [HR] = 10.66), a young age (p = 0.008, HR = 0.96), and tumor progression preoperatively (p = 0.042, HR = 2.32) significantly increased the risk of recurrence, whereas tumor size or histologic composition did not. A good postoperative facial nerve function (House-Brackmann grade 1-2) was achieved in 85%. The risk of postoperative facial nerve paresis or paralysis increased with tumor size (p < 0.001, OR = 1.52), but was not associated with the extent of tumor removal, histologic composition, or patient demographics.

CONCLUSIONS

Translabyrinthine surgery is an effective treatment for vestibular schwannoma, with a good local control rate and facial nerve outcome. The extent of tumor removal is a clinically relevant predictor for tumor recurrence, as are young patient age and preoperative tumor progression. A large preoperative tumor size is associated with a higher risk of postoperative facial nerve paresis or paralysis.

Surgical management for large vestibular schwannomas: a systematic review, meta-analysis, and consensus statement on behalf of the EANS skull base section

BACKGROUND AND OBJECTIVE

The optimal management of large vestibular schwannomas continues to be debated. We constituted a task force comprising the members of the EANS skull base committee along with international experts to derive recommendations for the management of this problem from a European perspective.

MATERIAL AND METHODS

A systematic review of MEDLINE database, in compliance with the PRISMA guidelines, was performed. A subgroup analysis screening all surgical series published within the last 20 years (January 2000 to March 2020) was performed. Weighted summary rates for tumor resection, oncological control, and facial nerve preservation were determined using meta-analysis models. This data along with contemporary practice patterns were discussed within the task force to generate consensual recommendations regarding preoperative evaluations, optimal surgical strategy, and follow-up management.

RESULTS

Tumor classification grades should be systematically used in the perioperative management of patients, with large vestibular schwannomas (VS) defined as > 30 mm in the largest extrameatal diameter. Grading scales for pre- and postoperative hearing (AAO-HNS or GR) and facial nerve function (HB) are to be used for reporting functional outcome. There is a lack of consensus to support the superiority of any surgical strategy with respect to extent of resection and use of adjuvant radiosurgery. Intraoperative neuromonitoring needs to be routinely used to preserve neural function. Recommendations for postoperative clinico-radiological evaluations have been elucidated based on the surgical strategy employed.

CONCLUSION

The main goal of management of large vestibular schwannomas should focus on maintaining/improving quality of life (QoL), making every attempt at facial/cochlear nerve functional preservation while ensuring optimal oncological control, thereby allowing to meet patient expectations. Despite the fact that this analysis yielded only a few Class B evidences and mostly expert opinions, it will guide practitioners to manage these patients and form the basis for future clinical trials.

Facial Nerve Outcomes After Vestibular Schwannoma Microsurgical Resection in Neurofibromatosis Type 2

OBJECTIVE

The aim of this study is to investigate facial nerve outcomes after microsurgical resection in neurofibromatosis type 2 (NF2) compared to sporadic tumors.

STUDY DESIGN

Single institutional retrospective chart review.

SETTING

Tertiary referral center.

METHODS

All adult patients with NF2 vestibular schwannoma (VS) or sporadic VS who underwent microsurgical resection from 2008 to 2019 with preoperative magnetic resonance imaging (MRI) and 1 year of postsurgical follow-up were included. The primary outcome measure was postoperative House-Brackmann (HB) facial nerve score measured at first postoperative visit and after at least 10 months.

RESULTS

In total, 161 sporadic VSs and 14 NF2 VSs met inclusion criteria. Both median tumor diameter (NF2, 33.5 mm vs sporadic, 24 mm, P = .0011) and median tumor volume (NF2, 12.4 cm³ vs sporadic, 2.9 cm³, P = .0005) were significantly greater in patients with NF2. The median follow-up was 24.9 months (range, 12-130.1). Median facial nerve function after 1 year for patients with NF2 was HB 3 (range, 1-6) compared to HB 1 (range, 1-6) for sporadic VS (P = .001). With multivariate logistic regression, NF2 tumors (odds ratio [OR] = 13.9, P = .001) and tumor volume ≥3 cm³ (OR = 3.6, P = .025) were significantly associated with HB ≥3 when controlling for age, sex, extent of tumor resection, translabyrinthine approach, and prior radiation.

CONCLUSION

Tumor volume >3 cm³ and NF2 tumors are associated with poorer facial nerve outcomes 1 year following microsurgical resection.

Vestibular schwannoma: predictive factors of long-term postoperative neurological outcome

Introduction: Vestibular schwannoma (VS) is a slow-growing, benign tumor that is usually diagnosed when symptoms develop. Surgical management aims to reduce long-term sequelae (LTS) associated with late diagnosis.Objective: Identify predictive factors of LTS after VS surgery and clinical outcome measured by modified Rankin scale (mRS).Methods: This cohort study included patients submitted to VS surgery from 1999 to 2014, with a mean follow-up of 6.4 ± 4.5 years. Disability was assessed across the mRS the primary outcome was defined by scores 3 to 6, which implied poor outcome in neurological recovery. Predictive factors were identified through multivariate logistic regression.Results: A total of 101 patients were included in this study. Fifty-one (50.49%) presented mRS ≥ 3 on the late postoperative period. Men comprise 22.8%, and the mean age was 47.1 ± 16.0 years (range19-80). Patients with mRS ≥ 3 presented larger tumors (3.7 ± 1.1 cm vs. 3.2 ± 1.0 cm, p < .001), less total resection (50% vs. 76.7%, p < .010) and more neurofibromatosis II(NFII) (84.9% vs. 64.3%, p = .023). On multivariate analysis NFII, tumor size and type resection were predictive of degree of autonomy (mRS ≥3: NF II (OR 3.5, 95% CI 1.08-11.36, p = .036) and tumor size (each 1 cm, OR1.51, 95% CI 0.96-2.38, p = .050).Conclusion: Tumor size, presence of NFT II, type of surgical approach and number of surgeries were identified as predictive factors of functional sequelae in long-term follow-up after VS surgery.HighlightsOne-third of our patients presented some degree of disability that impact in autonomy (mRS ≥ 3) in the late postoperative period.Tumor size, NFII, surgical approach were predictive to comprise independency.Considering the cranial nerve monitoring and late diagnosis, our results can give some contribution to understanding the Brazilian profile of VS surgery.Our findings suggests the need to look over what it is well recognized and identify aspects that affect the prognosis such as functional disabilities in VS surgery.

Prognostic factors of facial nerve function after vestibular schwannoma removal via translabyrinthine approach

BACKGROUND

Prediction of facial function is a major concern when proposing surgery for patients with vestibular schwannoma (VS).

AIMS/OBJECTIVES

To evaluate postoperative facial function of patients who underwent operation of VS via a translabyrinthine approach (TL), and to analyze factors that influence facial functions.

MATERIAL AND METHODS

A total of 91 VS patients, who were operated via a TL approach, between March 1997 and December 2016, were analyzed. Demographics, tumor-related factors, and operative findings were collected. Facial function was assessed according to the House-Brackmann (HB) grading system before surgery, immediately after surgery, and 1-, 3-, 6-months, and 1 year after surgery.

RESULTS

In cases of patients that had a tumor that extended to the CPA, an unsatisfactory facial outcome was noted in 12 (30.0%) patients. FN outcomes after tumor removal depend on tumor size (p = .040). Among FN-related factors, only the FN recovery timing was correlated with facial outcomes (p = .030). Univariable and multivariable analysis revealed that tumor size and the timing of FN recovery were significant as favorable prognostic factors for good facial outcomes.

CONCLUSIONS AND SIGNIFICANCE

Tumor size and the FN recovery timing are significant prognostic factors of facial outcome in VS patients who underwent operations via a TL approach.

Long-Term Facial Nerve Outcomes after Microsurgical Resection of Vestibular Schwannomas in Patients with Preoperative Facial Nerve Palsy

Objectives  This study aimed at evaluating facial nerve outcomes in vestibular schwannoma patients presenting with preoperative facial nerve palsy. Design  A retrospective review. Setting  Single-institution cohort. Participants  Overall, 368 consecutive patients underwent vestibular schwannoma resection. Patients with prior microsurgery or radiosurgery were excluded. Main Outcome Measures  Incidence, House-Brackmann grade. Results  Of 368 patients, 9 had confirmed preoperative facial nerve dysfunction not caused by prior treatment, for an estimated incidence of 2.4%. Seven of these nine patients had Koos grade 4 tumors. Mean tumor diameter was 3.0 cm (range: 2.1-4.4 cm), and seven of nine tumors were subtotally resected. All nine patients were followed up clinically for ≥ 6 months. Of the six patients with a preoperative House-Brackmann grade of II, two improved to grade I, three were stable, and one patient worsened to grade III. Of the three patients with grade III or worse, all remained stable at last follow-up. Conclusions  Preoperative facial nerve palsy is rare in patients with vestibular schwannoma; it tends to occur in patients with relatively large lesions. Detailed long-term outcomes of facial nerve function after microsurgical resection for these patients have not been reported previously. We followed nine patients and found that eight (89%) of the nine patients had either stable or improved facial nerve outcomes after treatment. Management strategies varied for these patients, including rates of subtotal versus gross-total resection and the use of stereotactic radiosurgery in patients with residual tumor. These results can be used to help counsel patients preoperatively on expected outcomes of facial nerve function after treatment.

Role of Facial Nerve Motor-Evoked Potential Ratio in Predicting Facial Nerve Function in Vestibular Schwannoma Surgery Both Immediate and at 1 Year

OBJECTIVE

To determine whether transcranial electrical stimulation-induced facial motor-evoked potential (FMEP) monitoring of the facial nerve (FN) during vestibular schwannoma (VS) tumor resection can predict both immediate and 1 year postoperative FN functional outcome.

DESIGN

Prospective consecutive non-comparative observational case series.

SETTING

Tertiary referral center.

MAIN OUTCOME MEASURES

Facial function, immediate post operation and at 1 year using House-Brackmann (HB) grading scale.

METHODS

The study included 367 consecutive patients (men 178; women 189; age 13-81 years) monitored during primary sporadic VS microsurgery between November 2002 and April 2015. Neurofibromatosis type II, revision surgery, previous radiotherapy treatment, preoperative facial nerve weakness, and non-VS cases were excluded retrospectively during analysis of data. Data of facial function were missing from eight patients at 1 year and were excluded. The correlation between the final-to-baseline FMEP ratio and immediate and 1 year facial nerve function was examined.

RESULTS

Using logistic regression model, the cut-off points of FMEP ratio were 0.62 (PPV 0.96) and 0.59 (PPV 0.98) which predicted satisfactory FN function (HB grades 1 or 2) immediately postoperative and at 1 year after surgery, respectively.

CONCLUSION

Transcranial electrical stimulation FMEP is a valuable tool for monitoring facial nerve function during resection of vestibular schwannoma. Maintaining a FMEP event-to-baseline ratio of 60% or greater is predictive of satisfactory long-term FN function.

Ophthalmic Complications Following Acoustic Neuroma Resection

BACKGROUND

Past studies have shown high rates of ocular complications with the need for ophthalmic surgery following acoustic neuroma resection (ANR).

OBJECTIVE

To determine the rates of ophthalmic complications, referrals, and surgery following ANR, and the factors associated with poor outcomes.

METHODS

A retrospective study of ophthalmic outcomes in patients who underwent ANR was conducted, following institutional review board approval. Surgical approach, tumor size, tumor characteristics, completeness of resection, postoperative House-Brackmann grades, ocular complications, referrals to ophthalmology, and ophthalmic treatments were recorded.

RESULTS

Between 2007 and 2012, 174 patients underwent ANR. There were 3 surgical groups: retrosigmoid (n = 97), translabyrinthine (n = 59), and combined retrosigmoid and translabyrinthine (n = 18). Median tumor size was 2.2 cm. Postoperatively, 30% of patients had facial nerve dysfunction (House-Brackmann ≥3), which recovered to 19% by 1 mo and 8.6% by 1 yr following ANR. Fifty-six (32.9%) patients experienced ocular complications postoperatively, with lagophthalmos, dry eye, and blurry vision as the most common complications. Thirty-six (67.9%) of the patients who required ophthalmic treatment were managed nonsurgically, with just 13 (7.6%) patients requiring referral to an ophthalmologist. In total, only 9 (5.3%) patients received an ophthalmic procedure. Patients with tumors &gt;2 cm, those undergoing combined retrosigmoid and translabyrinthine resection, and those with severe facial nerve dysfunction which did not improve in the first month following surgery were more likely to have poor ophthalmic outcomes.

CONCLUSION

We present lower rates of ophthalmic complications following ANR than previously reported. Improved surgical technique, better postoperative eye care, and facial nerve monitoring most likely accounted for the improved ocular outcomes.

Total Facial Paralysis after Vestibular Schwannoma Surgery: Probability of Regaining Normal Function

The aim of the present study was to ascertain the precise fraction of vestibular schwannoma cases that recover to normal function after postoperative total facial nerve paralysis and to compare our results with those presented in the literature. This was a retrospective case review of 631 cases. Among the 132 cases with immediate postoperative facial nerve palsy (House Brackmann [HB] grade VI), only 2 (1.5%) recovered to normal function (HB grade I). In an attempt to compare our results with those of other series in the literature, we found a large variation in the incidence of recovery of this group of patients to grade I, ranging from 0% to 50%. Our analysis of the reported data revealed widely varying methods of data collection and presentation, making a scientifically valid comparison particularly difficult. According to our data, complete (HB grade I) or near-complete (HB grade II) facial nerve function recovery from an immediate postoperative grade VI palsy is extremely rare.

Functional Outcome of the Facial Nerve After Surgery for Vestibular Schwannoma: Prediction of Acceptable Long-Term Facial Nerve Function Based on Immediate Postoperative Facial Palsy

OBJECTIVE

To examine the relationship between immediate postoperative facial palsy and long-term facial palsy and identify a treatment strategy for vestibular schwannoma considering long-term outcomes of facial nerve function and tumor control.

METHODS

Patients (N = 385) who underwent surgery in a single institution were reviewed retrospectively; 12 patients with neurofibromatosis, 6 with preoperative radiosurgery, and 14 with multiple surgeries were excluded. The generalized estimating equation method was used to show the correlation between immediate and later postoperative facial palsy and to identify the cutoff grade of immediate postoperative facial palsy.

RESULTS

The tumor control rates for 1 year, 3 years, and 5 years were 88.7%, 83.9%, and 80.0%. Preservation of facial function above House-Brackmann (H-B) grades 1 and 2 was achieved in 47.9% of patients immediately postoperatively, in 50.1% after 1 month, and in 74.5% after >2 years. The immediate postoperative facial palsy grade showed a statistically significant relationship with the facial palsy grade on long-term follow-up (P < 0.001). H-B grade 3 immediate postoperative facial palsy was identified as the cutoff grade that showed the most significant relationship between the grade of immediate postoperative facial palsy and the grades above the cutoff (H-B grade 1-3) on long-term follow-up (P < 0.001).

CONCLUSIONS

H-B grade of immediate postoperative facial palsy can predict facial palsy at long-term follow-up. H-B grade 3 immediate postoperative facial palsy is the lowest tolerable grade that guarantees functional improvement on long-term follow-up. Planned facial nerve preservation surgery followed by radiosurgery is thought to be optimal treatment in patients with vestibular schwannoma for both tumor control and facial nerve function.

The anatomically intact but electrically unresponsive facial nerve in vestibular schwannoma surgery

BACKGROUND

Permanent facial nerve (FN) paresis after vestibular schwannoma surgery is distressing to both the patient and surgeon. Intraoperative electrophysiological testing has proven invaluable in reducing the incidence of FN injury and may assist in prognosticating long-term function.

OBJECTIVE

To report definitive FN outcomes among a cohort of patients with an unevokable but anatomically intact seventh nerve after microsurgical vestibular schwannoma resection.

METHODS

All patients undergoing vestibular schwannoma surgery between 2000 and 2010 at a single tertiary academic referral center were identified. Intraoperative FN monitoring data and definitive FN outcomes were reviewed, and all patients with an anatomically intact but electrically unresponsive FN were included.

RESULTS

Eleven patients met the inclusion criteria. The median preoperative and definitive postoperative FN scores were House-Brackmann grades 1 and 3, respectively. The median time to definitive FN recovery was 9.4 months.

CONCLUSION

These data demonstrate that even among this extreme subset, modern electroprognostic testing strategies are incapable of reliably predicting poor outcomes. Therefore, if FN continuity is maintained, attempts at same-surgery FN repair should not be pursued.

Use of supramaximal stimulation to predict facial nerve outcomes following vestibular schwannoma microsurgery: results from a decade of experience

Object

The goal of vestibular schwannoma surgery is tumor removal and preservation of neural function. Intraoperative facial nerve (FN) monitoring has emerged as the standard of care, but its role in predicting long-term facial function remains a matter of debate. The present report seeks to describe and critically assess the value of applying current at supramaximal levels in an effort to identify patients destined for permanent facial paralysis.

Methods

Over more than a decade, the protocol for stimulating and assessing the FN during vestibular schwannoma surgery at the authors' institution has consisted of applying pulsed constant-current stimulation at supramaximal levels proximally and distally following tumor resection to generate an amplitude ratio, which subtracted from 100% yields the degree to which the functional integrity of the FN “dropped off” intraoperatively. These data were prospectively collected and additional variables that might impact postoperative FN function were retrospectively reviewed from the medical record. Only patients with anatomically intact FNs and > 12 months of follow-up data were analyzed.

Results

There were 267 patients available for review. The average posterior fossa tumor diameter was 24 mm and the rate of long-term good (House-Brackmann Grade I–II) FN function was 84%. Univariate logistic regression analysis revealed that prior treatment, neurofibromatosis Type 2 status, tumor size, cerebellopontine angle extension, subjectively thinned FN at the time of operation, minimal stimulation threshold, percent dropoff by supramaximal stimulation (SMS), and postoperative FN function all correlated statistically (p < 0.05) with long-term FN function. When evaluating patients with significant FN weakness at the time of hospital discharge, only the percent dropoff by SMS remained a significant predictor of long-term FN function. However, the positive predictive value of SMS for long-term weakness is low, at 46%.

Conclusions

In a large cohort of patients, the authors found that interrogating intraoperative FN function with SMS is safe and technically simple. It is useful for predicting which patients will ultimately have good facial function, but is very limited in identifying patients destined for long-term facial weakness. This test may prove helpful in the future in tailoring less than gross-total tumor removal to limit postoperative facial weakness.

Fundus obliteration and facial nerve outcome in vestibular schwannoma surgery

The major objectives in vestibular schwannoma (VS) surgery have evolved from reducing mortality to functional preservation of the facial nerve and hearing. Absence of fluid between the lateral end of the VS and the internal auditory canal fundus on magnetic resonance imaging (MRI) appeared to have a negative influence on hearing outcome. Our goal was to study the prognostic significance of fundus obliteration on facial nerve function after VS surgery in patients with clinically normal facial function. We performed a retrospective review in a tertiary referral neurotology unit or 110 consecutive patients with a surgically removed VS and normal preoperative facial nerve function. Facial nerve function was evaluated at 1 month and 1 year by using the House-Brackmann (HB) scale and correlated to fundus obliteration on MRI. Facial nerve function was intact preoperatively in 114 of 123 patients (92.7%). We noticed a statistically significant difference and worse short-term outcome when the fundus was obliterated: 29.7% had HB 3 or more versus 13.0% if no fundus obliteration was seen. This statistically significant difference disappeared at 1 year. Fundus obliteration has a negative prognostic influence on short-term facial nerve function after VS surgery in patients with clinically normal facial function preoperatively.

Stage II vestibular schwannoma: predictive factors for postoperative hearing loss and facial palsy

OBJECTIVES

To assess predictive factors for deafness and facial palsy after vestibular schwannoma surgery on a translabyrinthine or retrolabyrinthine approach, and to compare sequela results to those for gamma knife radiosurgery.

PATIENTS AND METHODS

A retrospective study included 70 patients operated on for stage II vestibular schwannoma (Koos classification). Postoperative hearing was assessed on pure-tone average and speech discrimination score, and facial palsy on the House and Brackmann classification, preoperatively and at 1 year postoperatively. Various predictive factors were assessed for both. Statistical analysis used the Fischer exact test, with a significance threshold of P<0.05.

RESULTS

Hearing was conserved in 18.9% of patients operated on with a retrolabyrinthine approach, with 8.1% conserving useful hearing. Facial function was conserved in 91.4%. Predictive factors for hearing conservation did not achieve statistical significance, but showed trends for: preoperative pure-tone average threshold≤30dB and speech discrimination score≥ 70%, age less than 55 years, tinnitus, nearly normal auditory brainstem response (ABR) latency, and homogeneous tumor on MRI. Predictive factors for conserved facial function likewise did not achieve statistical significance, but showed trends for: age less than 55 years, deafness of progressive onset, absence of cardiovascular risk factors, nearly normal ABR latency and tumor size<13.5mm on MRI.

CONCLUSION

Facial nerve risk is largely the same with surgery or gamma knife radiosurgery. Concerning hearing, gamma knife radiosurgery seems to provide better hearing conservation, but only over the short term.

Facial nerve function after vestibular schwannoma surgery

OBJECT

The object of this study was to evaluate long-term postoperative facial nerve (FN) function in patients undergoing vestibular schwannoma (VS) surgery.

METHODS

The authors retrospectively reviewed the clinical course of patients affected by isolated VSs with normal preoperative FN function, with no previous surgical or radiotherapeutic treatment, and who underwent surgery between 1987 and 2007. Facial nerve function was clinically evaluated according to the House-Brackmann (HB) scale. The minimum postoperative follow-up was 12 months.

RESULTS

Among the 1550 patients surgically treated at the authors' center, 1151 matched inclusion criteria for the present study. The FN was anatomically interrupted in 48 cases (4.2%), and 51 patients (4.4%) underwent subtotal tumor removal and were considered separately. Among the 1052 patients with anatomically preserved FNs and total tumor removal, 684 (65%) enjoyed postoperative HB Grade I or II and 309 (29.4%) enjoyed Grade III, with the remaining 59 cases (5.6%) suffering unsatisfactory results (HB Grades IV-VI). As expected, FN function results deteriorated in cases of larger tumors.

CONCLUSIONS

The main factor influencing postoperative FN function was tumor size. Although there was a progressive deterioration in FN function outcome in relation to tumor size, a cutoff point between satisfactory and unsatisfactory results could be identified at around 2 cm in maximum extrameatal tumor diameter, with the "optimal size" for surgery identified at < 1 cm. This finding emphasizes the importance of an early diagnosis and should be kept in mind when selecting the correct timing for VS removal. For small lesions, the results following a middle cranial fossa approach were significantly worse as compared with those following the translabyrinthine and retrosigmoidretrolabyrinthine approaches.

Comparison of postoperative facial nerve outcomes between translabyrinthine and retrosigmoid approaches in matched-pair patients

OBJECTIVES/HYPOTHESIS

The objective was to assess whether the translabyrinthine approach for acoustic tumor removal offers better postoperative facial nerve function compared with the retrosigmoid approach.

STUDY DESIGN

Retrospective case review from a tertiary otology referral center.

METHODS

Patients who had undergone either retrosigmoid or translabyrinthine approach for removal of acoustic neuroma from January 1, 1980, to December 31, 1999, were included in the study. Two groups of patients were created, one containing retrosigmoid cases and the other, translabyrinthine. Attempts were made to match each retrosigmoid case to a translabyrinthine case with regard to tumor size, patient age, and date of operation. This matching served to eliminate these variables from influencing postoperative facial nerve outcomes. From an initial pool of 450 patients, 35 pairs of patients were matched for the study. Facial nerve functions were reported at immediate, 3-month, and 1-year postoperative periods.

RESULTS

Patient demographics demonstrated that matched patients had almost identical tumor size, patient age, and date of operation. Comparisons of postoperative facial nerve functions between the matched groups revealed that retrosigmoid approach carried 2.86 times higher risk of facial nerve dysfunction during the immediate postoperative period. However, by 1 year, the facial nerve outcomes were similar between the two groups.

CONCLUSION

Compared with the translabyrinthine approach, retrosigmoid approach carries a higher risk of postoperative facial nerve dysfunction during the immediate postoperative period. However, long-term facial nerve outcomes are identical between the two approaches.

Factors associated with preservation of facial nerve function after surgical resection of vestibular schwannoma

Avoidance of facial nerve palsy is one of the major goals of vestibular schwannoma (VS) microsurgery. In this study, we examined the significance of previously implicated prognostic factors (age, tumor size, the extent of resection and the surgical approach) on post-operative facial nerve function. We selected all VS patients from prospectively collected database (1984–2009) who underwent microsurgical resection as their initial treatment for histopathologically confirmed VS. The effect of variables such as surgical approach, tumor size, patient age and extent of resection on rates facial nerve dysfunction after surgery, were analyzed using multivariate logistic regression. Patients with preoperative facial nerve dysfunction (House-Brackman [HB] score 3 or higher) were excluded, and HB grade of 1 or 2 at the last follow-up visit was defined as “facial nerve preservation.” A total of 624 VS patients were included in this study. Multivariate logistic regression analysis found that only pre-operative tumor size significantly predicted poorer facial nerve outcome for patients followed-up for ≥6 and ≥12 months (OR 1.27, 95% CI 1.09–1.49, p < 0.01; OR 1.35, 95% CI 1.10–1.67, P < 0.01, respectively). We found no significant relationship between facial nerve function and age, extent of resection, surgical approach, or tumor size (when extent of resection and surgical approach were included in the regression analysis). Because facial nerve palsy is a debilitating and psychologically devastating condition for the patient, we suggest altering surgical aggressiveness in patients with unfavorable tumor anatomy, particularly in cases with large tumors where overaggressive resection might subject the patient to unwarranted risk. Residual disease can be followed and controlled with radiosurgery if interval growth is noted.

Intraoperative neurophysiological monitoring in vestibular schwannoma surgery: advances and clinical implications

OBJECT

Intraoperative neurophysiological monitoring has become an integral part of vestibular schwannoma surgery. The aim of this article was to review the different techniques of intraoperative neurophysiological monitoring in vestibular schwannoma surgery, identify the clinical impact of certain pathognomonic patterns on postoperative outcomes of facial nerve function and hearing preservation, and highlight the role of postoperative medications in improving delayed cranial nerve dysfunction in the different reported series.

METHODS

The authors performed a review of the literature regarding intraoperative monitoring in acoustic/vestibular schwannoma surgery. The different clinical series representing different monitoring techniques were reviewed. All the data from clinical series were analyzed in a comprehensive and comparative model.

RESULTS

Intraoperative brainstem auditory evoked potential monitoring, direct cochlear nerve action potential monitoring, and facial nerve electromyography are the main tools used to assess the functional integrity of an anatomically intact cranial nerve. The identification of pathognomonic brainstem auditory evoked potential and electromyography patterns has been correlated with postoperative functional outcome. Recently, perioperative administration of intravenous hydroxyethyl starch and nimodipine as vasoactive and neuroprotective agents was shown to improve vestibular schwannoma functional outcome in few reported studies.

CONCLUSIONS

Recent advances in electrophysiological technology have considerably contributed to improvement in functional outcome of vestibular neuroma surgery in terms of hearing preservation and facial nerve paresis. Perioperative intravenous nimodipine and hydroxyethyl starch may be valuable additions to surgery.

Long-term facial nerve clinical evaluation following vestibular schwannoma surgery

BACKGROUND: Facial function is important in accompaniment of patients operated on vestibular schwannoma (VS). OBJETIVE: To evaluate long term facial nerve function in patients undergoing VS resection and to correlate tumor size and facial function in a long-term follow-up. METHOD: Transversal study of 20 patients with VS operated by the retrosigmoid approach. House-Brackmann Scale was used preoperatively, immediately after surgery and in a long-term follow-up. Student t test was applied for statistic analysis. RESULTS: In the immediate postoperative evaluation, 65% of patients presented FP of different grades. Improvement of facial nerve function (at least of one grade) occurred in 53% in the long-term follow-up. There was statistically significant difference in facial nerve outcome in long-term follow-up when tumor size was considered (p<0.05). Conclusion: The majority of patients had improvement of FP in a long-term follow-up and tumor size was detected to be a factor associated with the postoperative prognostic.

Acoustic Neuroma in a Private Neurotology Practice: Trends in Demographics and Practice Patterns

OBJECTIVES/HYPOTHESIS

To determine whether changes in demographics and management of patients with acoustic neuromas occurred between the years 1990 and 2005.

STUDY DESIGN

Retrospective chart review.

METHODS

Charts of all 614 patients with a diagnosis of acoustic neuroma, excluding neurofibromatosis-2, from 1990 through 2005 were reviewed. Age at diagnosis, tumor size, hearing, and initial therapy (observation, stereotactic radiation, or surgical excision) were obtained. Patients were grouped by time period (1990-1994, 1995-2000, 2001-2005).

RESULTS

Mean age at diagnosis increased slightly from the middle period (53.4 yr) to the most recent (56.9 yr) (P < or = .025). The proportion of patients 65 years or older increased from 21% to 29% to 32%, respectively, but the change was not significant. Average tumor size decreased from 1.7 cm initially to 1.4 cm most recently (P < or = .039). There were no significant changes in hearing. Although surgical excision remains our most common treatment (58.5% in 2001-2005), it is becoming less frequent (>80% in earlier periods) (P < or = .001). Observation with serial imaging was recommended in 37.3% in 2001 to 2005 as compared with 18.3% and 11.6% in the previous two time periods (P < or = .001). These changes in initial treatment choices occurred for all age groups and primarily for small tumors. Use of radiation has increased only slightly, to 4.2% in the recent period.

CONCLUSION

: Patients with acoustic neuroma are presenting with increased age and smaller tumors compared with 16 years ago. However, these changes cannot totally account for the large change in treatment trends. Technology and demographics are influential in these changes, but other difficult to measure forces, such as patient influence and patient use of the Internet, are also factors.

Facial Nerve Monitoring Parameters As a Predictor of Postoperative Facial Nerve Outcomes after Vestibular Schwannoma Resection

OBJECTIVE

To evaluate whether the intraoperative stimulus threshold and response amplitude measurements from facial electromyography can predict facial nerve function at 1 year after vestibular schwannoma resection.

STUDY DESIGN

Prospective study.

SETTING

Tertiary academic center.

PATIENTS

Seventy-four consecutive vestibular schwannoma patients.

INTERVENTION

The minimal stimulus intensity (in milliamperes) and electromyographic response amplitude (in microvolts) were recorded during stimulation applied to the proximal facial nerve after vestibular schwannoma removal.

MAIN OUTCOME MEASURE

Facial nerve outcomes at 1 year were evaluated using the House-Brackmann scale. Analysis was then performed to evaluate whether these electrophysiologic recordings and tumor size could predict facial nerve functional outcomes.

RESULTS

Of the 74 patients, 66 of 74 (89%) had House-Brackmann Grade I or II facial nerve function and 8 of 74 (11%) had House-Brackmann Grade III-VI function at 1 year after surgery. If standards were set for intraoperative minimal stimulus intensity of 0.05 mA or less and response amplitude of 240 microV or greater, the authors were able to predict a House-Brackmann Grade I or II outcome in 56 of 66 (85%) patients at 1 year after surgery. With these same electrophysiologic parameters, only 1 of 8 (12%) House-Brackmann Grade III-VI patients also met this standard and thus gave a false-positive result. Logistic regression analysis of the data showed that both a stimulus threshold of 0.05 mA or less and a response amplitude of 240 microV or greater predicted a House-Brackmann Grade I or II outcome with a 98% probability. However, stimulus threshold or response amplitude alone had a much lower probability of the same result. In addition, although tumor size was found to independently predict facial nerve outcomes at 1 year, it did not improve the ability to predict facial nerve function over a model using stimulus intensity and amplitude alone.

CONCLUSION

Individually, minimal stimulus intensity or response amplitude was less successful in predicting long-term postoperative facial nerve function. However, if both parameters are considered together, the study demonstrates that they are good prognostic indicators for facial nerve function at 1 year after surgery.

Facial Paralysis and Surgical Rehabilitation: A Quality Of Life Analysis in a Cohort of 1,595 Patients after Acoustic Neuroma Surgery

OBJECTIVES

On the basis of survey results of the Acoustic Neuroma Association, we report patient ratings of facial dysfunction and outcomes for various facial rehabilitative therapies after surgical treatment of acoustic neuroma (AN). We assessed patients' perceived quality of life (QOL) and reviewed the literature regarding facial dysfunction and its management associated with AN.

STUDY DESIGN

The Acoustic Neuroma Association mailed a detailed questionnaire to 2,372 members to identify preoperative and postoperative symptoms, complications, and long-term effects on physical and psychosocial function. A cohort of 1,595 (82.2%) respondents who underwent surgical treatment of ANs reported their experiences with facial dysfunction.

PATIENTS

Of all 1,940 survey respondents, 1,682 of 1,875 that had ANs underwent surgical treatment. The study included 1,595 patients with ANs (82.2% of all respondents) who underwent surgical treatment by way of the translabyrinthine, suboccipital, or middle fossa approaches and excluded 87 respondents who did not report the type of surgical approach.

METHODS

Respondents answered questions intended to qualify and quantify the degree that facial dysfunction impacted QOL parameters. Responses were analyzed for tumor size, surgical approach, patient age, and sex. Statistical analysis was performed using SPSS software.

RESULTS

In our analysis, 11% of all respondents experienced some degree of preoperative facial weakness or eye problems. Of all respondents, 45.5% (725 patients) experienced worsened facial weakness caused by surgery, and of these, 72% reported that it was permanent. The most commonly used successful therapy for facial reanimation for 271 (19.6%) patients was placement of a gold weight. The factor most often associated with poor outcome was a large tumor. Of all respondents, 28% felt significantly affected by facial weakness, 63% felt their smile was symmetric, and 70% were content "quite a bit" or "very much" with their QOL.

CONCLUSIONS

In this large cohort study of AN patients, facial dysfunction was a significant morbidity. Physicians should be aware of the risk factors identified, specifically large tumor size and the impact facial dysfunction has on QOL, when counseling patients regarding optimal management of AN.

Intraoperative cranial nerve monitoring

The purpose of intraoperative monitoring is to preserve function and prevent injury to the nervous system at a time when clinical examination is not possible. Cranial nerves are delicate structures and are susceptible to damage by mechanical trauma or ischemia during intracranial and extracranial surgery. A number of reliable electrodiagnostic techniques, including nerve conduction studies, electromyography, and the recording of evoked potentials have been adapted to the study of cranial nerve function during surgery. A growing body of evidence supports the utility of intraoperative monitoring of cranial nerve nerves during selected surgical procedures.

Intraoperative Monitoring and Facial Nerve Outcomes after Vestibular Schwannoma Resection

OBJECTIVE

To determine the predictive value of proximal facial nerve electrical threshold and proximal-to-distal facial muscle compound action potential amplitude ratio on facial nerve outcomes after resection of vestibular schwannomas.

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary care hospital.

PATIENTS

Two hundred twenty-nine patients undergoing resection of vestibular schwannomas with intraoperative facial nerve monitoring at a single institution.

INTERVENTION

All patients underwent resection of vestibular schwannomas with the use of intraoperative monitoring.

MAIN OUTCOME MEASURE

Facial nerve function was classified according to the House-Brackmann scale at the patient's last office follow-up. Last follow-up was at least 6 months after surgery.

RESULTS

Good facial nerve function (House-Brackmann Grade I or II) was observed in 87% of the patients at their last office follow-up. Proximal-to-distal amplitude ratio and proximal electric threshold were statistically significant in predicting facial nerve outcome. A mathematical model predicting the probability of good outcome on the basis of the intraoperative parameters is presented.

CONCLUSION

Intraoperative monitoring has significantly decreased facial nerve morbidity in vestibular schwannoma surgery. Despite the advances in surgery and monitoring, a group of patients still have poor facial nerve outcomes. The use of intraoperative nerve monitoring may be able to predict poor long-term facial nerve outcomes and thus modify the timing of rehabilitation.

Surgical excision of acoustic neuroma: patient outcome and provider caseload

OBJECTIVES/HYPOTHESIS

For many complex surgical procedures, larger hospital or surgeon caseload is associated with better patient outcome. We examined the volume-outcome relationship for surgical excision of acoustic neuromas.

STUDY DESIGN

Retrospective cohort study.

METHODS

The Nationwide Inpatient Sample (1996 to 2000) was used. Multivariate regression analyses were adjusted for age, sex, race, payer, geographic region, procedure timing, admission type and source, medical comorbidities, and neurofibromatosis status.

RESULTS

At 265 hospitals, 2643 operations were performed by 352 identified primary surgeons. Outcome was measured on a four-level scale at hospital discharge: death (0.5%) and discharge to long-term care (1.2%), to short-term rehabilitation (4.4%), and directly to home (94%). Outcomes were significantly better after surgery at higher-volume hospitals (OR 0.47 for fivefold-larger caseload, P <.001) or by higher-volume surgeons (OR 0.46, P <.001). Of patients who had surgery at lowest-volume-quartile hospitals, 12.3% were not discharged directly home, compared with 4.1% at highest-volume-quartile hospitals. There was a trend toward lower mortality for higher-volume hospitals (P =.1) and surgeons (P =.06). Of patients who had surgery at lowest-caseload-quartile hospitals, 1.1% died, compared with 0.6% at highest-volume-quartile hospitals. Postoperative complications (including neurological complications, mechanical ventilation, facial palsy, and transfusion) were less likely with high-volume hospitals and surgeons. Length of stay was significantly shorter with high-volume hospitals (P =.01) and surgeons (P =.009). Hospital charges were lower for high-volume hospitals (by 6% [P =.006]) and surgeons (by 6% [P =.09]).

CONCLUSION

For acoustic neuroma excision, higher-volume hospitals and surgeons provided superior short-term outcomes with shorter lengths of stay and lower charges.