Prognostic clinical and radiological parameters for immediate facial nerve function following vestibular schwannoma surgery

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.

Endoscope-Assisted Retrosigmoid Approach for Vestibular Schwannomas With Intracanalicular Extensions: Facial Nerve Outcomes

Objective

To explore the role of neuroendoscope assistance during surgical resection of the intracanalicular portion of vestibular schwannomas via the retrosigmoid approach and the subsequent early facial nerve outcomes.

Methods

Patients of vestibular schwannoma with intracanalicular extensions undergoing retrosigmoid dissection at a single institution were retrospectively analyzed in this study. Several surgical techniques were applied to ensure maximal and safe removal of tumors. Tumors extending less than 10 mm into the internal acoustic canal (IAC) were classified as Grade A, while those extending over 10 mm into IAC were taken as Grade B. Neuroendoscope was applied at the end of microscopic phase to search for potential remnants for Grade B tumors. Absolute tumor extension was defined and measured. House and Brackmann (HB) scale was used to evaluate immediate CN VII outcomes.

Results

Of the 61 patients, there were 38 females and 23 males. A total of 18 (29.51%) cases were Koos Grade II, 12 (19.67%) cases Koos Grade III, and 31 (50.82%) cases Koos Grade IV. There were 38 cases (62.30%) of Grade A and 23 cases (37.70%) of Grade B. Gross total resection was achieved in 60 cases (98.36%). Four cases of intracanalicular remnants were detected and completely removed under endoscopic visualizations. There was a significantly higher proportion (17%, p = 0.02) of intracanalicular remnants in Grade B than Grade A. CN VII and VIII were anatomically preserved in all cases. A total of 55 cases (90.16%) retained good (HB Grades 1 and 2) facial nerve outcomes.

Conclusions

In Grade B vestibular schwannomas, after maximal microsurgical removal, endoscopic evaluation of the intracanalicular portion revealed residual tumors in 17% of the patients. Hence endoscopic evaluation of the potential intracanalicular remnants for tumor extending over 10 mm within IAC (Grade B) is recommended.

Vestibular Schwannoma Cerebellopontine Angle Position Impacts Facial Outcome

OBJECTIVES/HYPOTHESIS

To determine the impact of vestibular schwannoma (VS) position relative to the internal auditory canal (IAC) on postoperative facial nerve function and extent of surgical resection.

STUDY DESIGN

Retrospective chart review.

METHODS

Retrospective review of patients undergoing resection of large (≥25 mm) VSs. Outcome measures included early (≤1 month) facial function, long-term (≥1 year) facial function and extent of resection. Tumor measurements included the greatest dimension, dimension anterior to the IAC axis, dimension posterior to the IAC axis, and a ratio of posterior-to-anterior dimension (PA ratio).

RESULTS

A total of 127 patients met inclusion criteria. In early follow-up, 60% patients had good (House-Brackmann I-II), and 40% patients had poor (House-Brackmann III-VI) facial function. In long-term follow-up, 71% patients had good, and 29% patients had poor facial function. A total of 72% of patients underwent gross total resection (GTR) of their tumors. Patients with good facial function had significantly larger PA ratios than patients with poor function both early and long term; however, greatest dimension was the more clearly significant independent predictor of facial outcomes. A larger PA ratio was observed in patients in whom GTR was achieved, but this association was potentially confounded by surgeon preferences and was not statistically significant after controlling for surgical site.

CONCLUSIONS

This study demonstrates that VS position relative to the IAC axis can be used along with tumor size to predict postoperative facial outcomes. A greater proportion of tumor posterior to the IAC axis was associated with significantly better facial outcomes.

LEVEL OF EVIDENCE

4 Laryngoscope, 2021.

Delayed Facial Nerve Palsy Following Resection of Vestibular Schwannoma: Clinical and Surgical Characteristics

OBJECTIVE

Analyze delayed facial nerve palsy (DFNP) following resection of vestibular schwannoma (VS) to describe distinct characteristics and facial nerve (FN) functional course.

STUDY DESIGN

Prospective cohort with retrospective review.

SETTING

Academic medical center.

PATIENTS

Consecutive patients undergoing VS resection 11/2017 to 08/2020. Exclusion criteria: preoperative House-Brackmann (HB) ≥ III, postoperative HB ≥ III without delayed palsy, <30 days follow-up.

INTERVENTIONS

VS resection with intraoperative electromyographic monitoring.

MAIN OUTCOME MEASURES

FN outcomes utilizing the HB scale; comparison between patients with DFNP (deterioration greater than one HB grade 24 hours to 30 days postoperatively) vs. those with HBI-II throughout.

RESULTS

Two hundred eighty-eight patients met criteria: mean age 47.6 years, 36.1% male; 24.0% middle cranial fossa, 28.5% retrosigmoid, 47.6% translabyrinthine. DFNP occurred in 31 (10.8%) patients with average time to onset of 8.1 days. Of these, 22 (71.0%) recovered HBI-II and 3 (9.7%) recovered HBIII. Patients who experienced DFNP, on average, had larger maximum tumor diameter (23.4 vs. 18.7 mm, p = 0.014), lower rate of gross-total resection (54.8% vs. 75.5%, p = 0.014), and lower rate of ≥100 μV FN response to 0.05 mA stimulus intraoperatively (80.6% vs. 94.9%, p = 0.002). Compared to overall incidence of DFNP, translabyrinthine approach demonstrated higher incidence (15.3%, p = 0.017) while retrosigmoid lower (3.7%, p = 0.014). In multivariable logistic regression, patients with FN response ≥100 μV to 0.05 mA stimulus were 72.0% less likely to develop DFNP (p = 0.021).

CONCLUSIONS

Intraoperative electromyographic facial nerve response, tumor size, surgical approach, and extent of resection may play a role in development of DFNP following resection of VS. Most patients who develop DFNP recover near-normal function.

The Influence of Extent of Resection and Tumor Morphology on Facial Nerve Outcomes Following Vestibular Schwannoma Surgery

OBJECTIVE

To determine the influence extent of resection and tumor characteristics on facial nerve (FN) outcomes following microsurgical resection of vestibular schwannoma (VS).

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary referral center.

PATIENTS

Three hundred eighty-five patients who underwent VS microsurgical resection.

INTERVENTIONS

Microsurgical VS resection.

MAIN OUTCOME MEASURES

House-Brackmann (HB) scores postoperatively. Good FN function was defined as HB grade I and II and poor FN function was defined as HB grade III and VI. Gross total resection (GTR) versus subtotal resection (STR). Propensity-score matching was used in subset analysis to balance tumor volume between the surgical cohorts, followed by multivariable analysis.

RESULTS

Seventy-one patients (18%) underwent STR and 314 patients (82%) underwent GTR. Two hundred fourteen patients (63%) had good FN function at 2 to 3 weeks postoperatively, and 80% had good FN function at 1 year. In single predictor analysis, STR did not influence FN function at 2 to 3 weeks (p = 0.65). In propensity-score matched subset analysis (N = 178), patients with STR were less likely to have poor FN function at 2 to 3 weeks (p = 0.02) independent of tumor volume (p = 0.004), but there was no correlation between STR and FN function at 1 year (p = 0.09). Ventral extension of tumor relative to the internal auditory canal plane was associated with poor FN outcomes at 2 to 3 weeks (p = 0.0001) and 1-year postop (p = 0.002).

CONCLUSIONS

When accounting for tumor volume, STR is protective in immediate postoperative FN function compared to GTR. Ventral extension of the tumor is a clinical predictor of long-term FN outcomes.

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.

Comparison of surgical outcomes in cystic and solid vestibular schwannomas: a systematic review and meta-analysis

Most studies reported that cystic vestibular schwannoma (CVS) surgery has a less favourable prognosis than solid vestibular schwannoma (SVS) surgery. However, some studies report that it is unclear whether surgical outcomes for these conditions exhibit significant differences. The aim of this meta-analysis was to pool the current literature and describe and analyse any differences in the clinical symptoms and surgical outcomes among CVS and SVS. PubMed, Embase, and Cochrane databases were searched following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines through April 22, 2020. Outcomes were analysed using a meta-analysis of the proportions. The results of the search yielded 17 studies that met the criteria for inclusion and analysis, involving 3074 participants (including 821 patients with CVSs and 2253 patients with SVSs). No significant differences in the extent of tumour resection (gross-total resection versus non-gross-total resection; RR, 0.93; 95% CI, 0.86-1.01; p = 0.096) and most other outcomes were noted between CVS and SVS cohorts. However, facial nerve function (House-Brackmann Grade I or II versus III or more) of CVS patients was worse (RR, 0.86; 95% CI, 0.78-0.93; p < 0.001) compared with SVS patients with more than 1 year of follow-up after surgery. The criteria of cystic acoustic neuroma needs to be further unified, and prospective cohort studies with larger sample sizes should be performed for further verification of these results in the future.

The Association of Vestibular Schwannoma Volume With Facial Nerve Outcomes After Surgical Resection

OBJECTIVE

To explore the relationship between tumor size and facial nerve outcomes following vestibular schwannoma (VS) resection.

STUDY DESIGN

Single institutional retrospective chart review of all adult patients with untreated sporadic VS who underwent surgical resection from 2008 to 2018 with preoperative magnetic resonance imaging (MRI) and 1 year of follow-up. The primary outcome measure was facial nerve outcome as assessed by the House-Brackmann facial nerve grading system.

RESULTS

One hundred sixty-seven patients, 54.5% female, with a median age of 49 years (20-76 years), were identified who underwent VS resection. Surgical resection was performed by translabyrinthine (76.7%), middle cranial fossa (14.4%), retrosigmoid (7.2%), and transpromontorial (1.8%) approaches. The median tumor diameter and volume were 25.3 mm (range: 4.1-47.1 mm) and 3.17 cm³ (range: 0.01-30.6 cm³ ), respectively. The median follow-up was 24.2 months (range: 12-114.2 months). Gross total resection was performed in 79% of cases, with residual tumor identified on MRI in 17% of cases. For patients with tumors <3 cm³ , 92.7% had grade 1 or 2 facial function after at least 1 year follow-up, compared to 81.2% for those with tumors >3 cm³ (univariate logistic regression OR = 2.9, P = .03). Tumor volume >3 cm³ was predictive of facial weakness on multivariate regression analysis (OR = 7.4, P = .02) when controlling for surgical approach, internal auditory canal extension, anterior extension, age, gender, and extent of resection.

CONCLUSIONS

Tumor volume >3 cm³ is associated with worse facial nerve outcomes 12 months following surgical resection.

LEVEL OF EVIDENCE

IV Laryngoscope, 131:E1328-E1334, 2021.

Can an Imaging Marker of Consistency Predict Intraoperative Experience and Clinical Outcomes for Vestibular Schwannomas? A Retrospective Review

Objective  The main purpose of this article is to determine if vestibular schwannoma consistency as determined by tissue intensity on T2-weighted magnetic resonance imagings (MRIs) is predictive of intraoperative experience and postoperative clinical outcomes. Study Design  Retrospective chart review. Setting  Tertiary referral center. Patients  Seventy-seven patients diagnosed with vestibular schwannomas who were treated with microsurgical resection. Intervention  Diagnostic. Main Outcome Measures  Intraoperative measures include totality of resection, surgical time and cranial nerve VII stimulation and postoperative measures include House-Brackmann grade and perioperative complications. Results  Tumor consistency determined via tissue intensity on MRI was only found to correlate with surgical time, with a softer tumor being associated with a longer surgical time ( p  < 0.0001). However, this was primarily driven by tumor volume with larger tumors being associated with longer surgical time based on multivariate analysis. None of the other intraoperative or postoperative measures considered were found to correlate with tumor consistency. Conclusions  Tumor consistency determined by MRI is not predictive of intraoperative experience or postoperative outcomes in vestibular schwannomas. Tumor volume is the strongest driver of these outcome measures as opposed to tumor consistency.

Nervus intermedius dysfunctions after vestibular schwannoma surgery: a prospective clinical study

OBJECTIVE

The purpose of this prospective study was to evaluate the dysfunction of the nervus intermedius (NI) after vestibular schwannoma (VS) surgery. The authors present a clinically feasible method for this purpose.

METHODS

In this prospective study, the authors included 30 patients who underwent surgery at the International Neuroscience Institute between May 2014 and February 2017 for resection of VS. The patients' taste sensation was examined using taste strips. Lacrimation was tested using the Schirmer I test. The clinical evaluation was performed before surgery and repeated at 2 weeks and at 6 months after surgery as well as during the follow-up, which extended up to 2 years. The authors tested the correlation between the NI dysfunctions and the House-Brackmann grade of facial nerve palsy.

RESULTS

The taste sensation was lost on the side of surgery in 2 patients (6.6%) and decreased in 4 patients (13.3%). The disturbance of taste sensation was not statistically correlated with dysfunctions of the motor portion of the facial nerve. The taste impairment resolved in 4 patients within 6 months, but 2 patients suffered from persistent loss of the taste sensation on the side of surgery during the follow-up. In 23 patients (76.6%), the baseline lacrimation was lower on the side of surgery, and it was significantly correlated with outcome for dysfunctions of the motor portion of the facial nerve. During the follow-up, baseline lacrimation improved in correlation with the improvement in the dysfunctions of the motor portion of the facial nerve. None of the patients reported change in salivation or nasal secretion.

CONCLUSIONS

The NI can be affected after VS surgery. The disturbance of baseline lacrimal secretion was correlated with dysfunctions of the motor portion of the facial nerve. However, the disturbance of the taste sensation was not correlated with the grade of facial nerve palsy. Dysfunctions of the NI should be evaluated and separately reported while analyzing facial nerve outcome after VS surgery.

Anterior Extension of Tumor is as Important as Tumor Size to Facial Nerve Outcome and Extent of Resection for Vestibular Schwannomas

Objectives  We examined vestibular schwannoma tumor dimension and direction of growth to determine whether these correlate with facial nerve outcome as well as extent of resection (EOR). Design  Retrospective review of prospectively maintained databases. Participants  206 patients were a part of this study. Main Outcome Measures  Tumor dimensions were measured using preoperative magnetic resonance imaging, and a series of ratios were then calculated to further characterize tumor dimension. Regression analyses were performed to investigate correlation with facial nerve outcome and EOR. Results  Patients with tumor extending >1.5 cm anterior to the internal auditory canal (IAC) (AB measurement) were three times more likely to have postoperative House-Brackman grades of 3 or worse. We also found that an EB/BF ratio (representing elongated growth parallel to the IAC axis) ≥1.1 was associated with half the risk of poor facial nerve outcome. Tumors with anterior-posterior diameter (AC measurement) >1.9 cm were five times less likely to undergo gross total resection (GTR). Furthermore, an increased degree of tumor extension into the IAC (DE measurement >2.4 cm) or an increased amount of brainstem compression (EB measurement >1.1 cm) were each associated with a nearly 3-fold decrease in the likelihood of GTR. Conclusion  Our study demonstrates that anterior extent of the tumor is as important as tumor size to facial nerve outcome and degree of resection for vestibular schwannomas.

Prognostic Indices for Predicting Facial Nerve Outcome following the Resection of Large Acoustic Neuromas

This study analyzes the simple ratio of anterior-to-posterior extension of large (>2.5 cm) acoustic neuromas relative to the internal auditory canal (ICA; anterior-posterior [A/P] index) as a tool for predicting risk of facial nerve (FN) injury. In total, 105 patients who underwent microsurgical resection for large acoustic neuromas were analyzed retrospectively. House-Brackmann (HB) scores were assessed immediately postoperatively, at 1 month, and at 1 year. Lateral-medial, inferior-superior, A/P, and maximum diameters were measured from preoperative magnetic resonance images. These measurements and the A/P index were analyzed using univariable and multivariable statistical models to assess relationship to FN outcomes. The retrosigmoid, translabyrinthine, and combined approaches were used, and the extent of resection was evaluated. For every 1 standard deviation increase in the A/P index, a patient was 3.87 times more likely have a higher postoperative HB score ( p  < 0.0001). Accordingly, for every 1-mm increase anterior to the IAC, a patient was 16% more likely have a higher postoperative HB score ( p  < 0.001). After controlling for tumor size, a patient was still 3.82 times more likely have a higher postoperative HB score for every 1 standard deviation increase in the A/P index ( p  < 0.0001). While larger tumor size trended toward worse postoperative HB scores, it was not statistically significant. Our prognostic index may be useful to assess the risk of FN injury preoperatively for large acoustic neuromas, while also providing information about the tumor-nerve relationship.

Prevalence and Surgical Implications of Dural Enhancement at the Porus Acusticus in Vestibular Schwannomas

OBJECTIVE

Demonstrate the association of radiographic dural enhancement with increased tumor adherence at the porus acusticus, which may influence completeness of resection and facial nerve outcome.

STUDY DESIGN

Case series with chart review.

SETTING

Academic referral center.

SUBJECTS AND METHODS

A total of 205 consecutive patients with histopathologically confirmed vestibular schwannoma (VS) were evaluated. Patients with tumors exhibiting dural enhancement on postgadolinium T1-weighted magnetic resonance imaging were identified and compared with matched controls. Completeness of resection, intraoperative details, and facial nerve outcomes were analyzed.

RESULTS

Excluding strictly intracanalicular tumors (n = 32, 16%) and those with NF2 (n = 10, 4.9%), the presence of dural enhancement was radiographically confirmed in 16 (9.8%) cases. Paired analysis did not reveal significant baseline differences between cases and controls. Subtotal resection was performed in 5 (31%) of the 16 patients with tumors exhibiting dural enhancement, in contrast to 1 (3%) of the matched controls (P = .01). Four (25%) demonstrated increased tumor adherence at the porus acusticus intraoperatively, compared with 1 control (3%, P = .04). Long-term facial nerve function was similar between cases and controls (81% vs 84% House-Brackmann I-II function, P = 1.00).

CONCLUSION

Dural enhancement is present in approximately 10% of extracanalicular VS. Dural enhancement at the porus acusticus may represent hypervascularity, dural reaction, or infiltration, and portends increased tumor adherence and greater likelihood of subtotal resection to preserve facial nerve function. To our knowledge, this is the first series that reports the prevalence of this phenomenon in VS and the potential surgical implications. Recognition preoperatively may be valuable toward patient counseling.

Surgery for sporadic vestibular schwannoma. Part IV. Predictive factors influencing facial nerve function after surgery

OBJECTIVE

To analyze the impact of various clinical, radiological and perioperative factors that could influence the facial nerve intraoperative disruption risk (CNVII-IDR) and its long-term function (CNVII-LTF) after vestibular schwannoma (VS) surgery.

MATERIAL AND METHODS

The study included 212 patients operated on for sporadic VS with no history of previous treatment for VS or CNVII palsy. The mean size of the tumor was 30 mm. Gross (210) or near-total (2) resections were carried out using the retrosigmoid (210) or translabyrinthine (2) approach. Correlation studies and multivariate regression analysis (RA) were performed.

RESULTS

In correlation studies, the CNVII-IDR was increased by: headaches and cerebellar ataxia if one of them was the first symptom of the tumor (33% and 29%, respectively, p=0.008); preoperative hydrocephalus (40% vs. 9%, p=0.01), tumor size >3 cm (18% vs. 5%, p<0.01), tumor volume >10 cm(3) (19% vs. 4%, p<0.01), right-sided location 15% vs. 6%, p=0.047), lateral "park-bench" position (19% vs. 5% for supine position, p<0.01) and the procedure order (16% for the first 106 procedures vs. 6% for the last 106 procedures, p<0.05). In RA the tumor volume (p=0.012), side of the tumor (p=0.028) and patient's position during surgery (p=0.016) independently affected the CNVII-IDR. The following factors correlated significantly with satisfactory CNVII-LTF (HB grades I-III): tumor stage <T4 (p=0.000), tumor size ≤3 cm (p=0.000), tumor volume ≤10 cm(3) (p=0.001), and left-sided location (p=0.048). Additional factors correlated significantly with very good CNVII-LTF (HB grades I-II): anterior CNVII displacement (p=0.044), nimodipine use (p=0.016), the absence of postoperative complications (p=0.019), CNVII responsive on final intraoperative EMG stimulation (p=0.000) and supine position during surgery (p=0.018). However, an independent impact on very good CNVII-LTF proved to be the tumor size (p=0.0000), side (p=0.0175), and nimodipine use (p=0.0349).

CONCLUSIONS

In our series, the factors related to size and side of the tumor confirmed an independent impact on CNVII-IDR and CNVIILTF. The significance of patient positioning may reflect the impact of learning curve as only the first 91 patients were operated on using the lateral "park-bench" position. An independent impact on CNVII-LTF was exerted by the perioperative use of nimodipine.

The extracisternal approach in vestibular schwannoma surgery and facial nerve preservation

The classical surgical technique for the resection of vestibular schwannomas (VS) has emphasized the microsurgical anatomy of cranial nerves. We believe that the focus on preservation of the arachnoid membrane may serve as a safe guide for tumor removal. Method The extracisternal approach is described in detail. We reviewed charts from 120 patients treated with this technique between 2006 and 2012. Surgical results were evaluated based on the extension of resection, tumor relapse, and facial nerve function. Results Overall gross total resection was achieved in 81% of the patients. The overall postoperative facial nerve function House-Brackmann grades I-II at one year was 93%. There was no recurrence in 4.2 years mean follow up. Conclusion The extracisternal technique differs from other surgical descriptions on the treatment of VS by not requiring the identification of the facial nerve, as long as we preserve the arachnoid envelope in the total circumference of the tumor.

Fluid-fluid level in cystic vestibular schwannoma: a predictor of peritumoral adhesion

OBJECT

The aim of this study was to evaluate the clinical results and surgical outcomes of cystic vestibular schwannomas (VSs) with fluid-fluid levels.

METHODS

Forty-five patients with cystic VSs and 86 with solid VSs were enrolled in the study. The patients in the cystic VSs were further divided into those with and without fluid-fluid levels. The clinical and neuroimaging features, intraoperative findings, and surgical outcomes of the 3 groups were retrospectively compared.

RESULTS

Peritumoral adhesion was significantly greater in the fluid-level group (70.8%) than in the nonfluid-level group (28.6%) and the solid group (25.6%; p < 0.0001). Complete removal of the VS occurred significantly less in the fluid-level group (45.8%, 11/24) than in the nonfluid-level group (76.2%, 16/21) and the solid group (75.6%, 65/86; p = 0.015). Postoperative facial nerve function in the fluid-level group was less favorable than in the other 2 groups; good/satisfactory facial nerve function 1 year after surgery was noted in 50.0% cases in the fluid-level group compared with 83.3% cases in the nonfluid-level group (p = 0.038).

CONCLUSIONS

Cystic VSs with fluid-fluid levels more frequently adhered to surrounding neurovascular structures and had a less favorable surgical outcome. A possible mechanism of peritumoral adhesion is intratumoral hemorrhage and consequent inflammatory reactions that lead to destruction of the tumor-nerve barrier. These findings may be useful in predicting surgical outcome and planning surgical strategy preoperatively.

Radiological and Clinical Factors Predicting the Facial Nerve Outcome following Retrosigmoid Approach for Large Vestibular Schwannomas (VSs)

Objective The aim of our study was to identify the radiological and clinical factors that predict postoperative facial nerve outcome following retrosigmoid approach for large vestibular schwannomas (VSs). Methods A total of 72 patients with large (≥ 3 cm) vestibular schwannomas was included in this retrospective study. Various parameters evaluated were age, gender, clinical presentation, tumor diameter in three planes, intrameatal extension, and pattern of growth. Results Age of the patient and presenting symptoms such as headache, ataxia, or preoperative facial nerve dysfunction correlated with poorer facial nerve outcome (p < 0.05). Patients with larger tumor volumes and extrameatal growth experienced a worse outcome (p < 0.05). Anterior and caudal extension (p = 0.001) correlated with poorer outcome, as well. Intrameatal extension and bony changes of the internal acoustic meatus did not correlate with the outcome (p > 0.05). Of the various examined factors, preoperative facial nerve function independently predicted postoperative facial nerve outcome. Conclusion Our study suggests that young patients with small tumor volume and normal facial nerve function at presentation are more likely to experience a good postoperative facial nerve outcome. These clinical and radiological parameters can be used to predict facial nerve outcome prior to surgery.

Surgical removal of giant acoustic neuromas

OBJECTIVE

The authors present the outcome of radical surgical removal of giant acoustic neuromas.

METHODS

Twenty-nine patients with acoustic neuroma with maximum diameter greater than 40 mm, submitted to surgery between the years 2005 and 2010, were reviewed by a retrospective study. The extension of tumor removal, surgical morbidity, facial nerve function, hearing, and evolution after surgery of preoperative neurologic conditions were the studied parameters.

RESULTS

All tumors were completely removed by a retrosigmoid approach, without perioperative mortality. As complications related to the surgery, there were three cases of local cerebrospinal fluid leak, one case of nasal cerebrospinal fluid leak, two cases of meningitis, one pseudomeningocele, and one case of transient lower cranial nerve dysfunction. The anatomic integrity of the facial nerve was preserved in 86% and facial function in 72%. In the 21 patients who did not need hypoglossal-facial anastomosis (72%), facial function was excellent or good (HB I-II) in 13 cases (45%), fair (HB III) in 5 cases (17%), and poor (HB IV) in 3 cases (10%). Before surgery, 12 patients (41%) had useful (H2) or moderate (H3) hearing. In 7 of these 12 patients (58%), it was possible to preserve some hearing function (with moderate hearing), after surgical removal of the tumors. Six patients presented with radiologic signs of hydrocephalus, two of them with visual disturbances. Two patients presented with trigeminal neuralgia (one contralateral), three with facial sensory loss and one with swallowing problems, that disappeared after surgery.

CONCLUSIONS

Total removal of large acoustic neuroma can be achieved by retrosigmoid approach with acceptable morbidity and no mortality. Preoperative neurologic symptoms recovered after surgery in most cases. Facial function preservation was possible in the majority of cases. Even in large tumors, hearing preservation should be attempted if the patient has useful hearing preoperatively.

Efficacy of facial nerve-sparing approach in patients with vestibular schwannomas

OBJECT

The goal of this article was to show that a combination of facial nerve-sparing microsurgical resection and Gamma Knife surgery (GKS) for expansion of any residual tumor can preserve good facial nerve function in patients with recurrent vestibular schwannoma (VS).

METHODS

Records of individuals treated by a single surgeon with a facial nerve-sparing technique for a VS between 1998 and 2009 were retrospectively analyzed for tumor recurrence. Of the 383 patients treated for VS, 151 underwent microsurgical resection, and 20 (13.2%) of these patients required postoperative retreatment for a significant expansion of residual tumor after microsurgery. These 20 patients were re-treated with GKS.

RESULTS

The rate of preservation of good facial nerve function (Grade I or II on the House-Brackmann scale) in patients treated with microsurgery for VS was 97%. Both subtotal and gross-total resection had excellent facial nerve preservation rates (97% vs 96%), although subtotal resection carried a higher risk that patients would require retreatment. In patients re-treated with GKS after microsurgery, the rate of facial nerve preservation was 95%.

CONCLUSIONS

In patients with tumors that cannot be managed with radiosurgery alone, a facial nerve-sparing resection followed by GKS for any significant regrowth provides excellent facial nerve preservation rates.

Hydrocephalus associated with vestibular schwannomas: management options and factors predicting the outcome

Object

The current, generally accepted optimal management for hydrocephalus related to vestibular schwannomas (VSs) is primary tumor removal, with further treatment reserved only for patients who remain symptomatic. Previous studies have shown, however, that this management can lead to an increase in surgery-related complications. In this study, the authors evaluated their experience with the treatment of such patients, with the aim of identifying the following: 1) the parameters correlating to the need for specific hydrocephalus treatment following VS surgery; and 2) patients at risk for developing hydrocephalus-related complications.

Methods

This was a retrospective study of a 400-patient series. The complication rates and outcomes following primary hydrocephalus treatment versus primary VS removal were compared. Patients undergoing primary tumor removal were further subdivided on the basis of the need for subsequent hydrocephalus treatment. The 3 categories of parameters tested for correlation with the need for such subsequent treatment as well as with heightened risk for developing complications were patient-, tumor-, and hydrocephalus-related.

Results

Of the entire series, 53 patients presented with hydrocephalus. Forty-eight of 53 patients underwent primary VS surgery, of whom 42 (87.5%) did not require additional hydrocephalus treatment. Of the 6 patients who did require additional hydrocephalus treatment, only 3 ultimately required a VP shunt. Factors correlating to the need of hydrocephalus treatment after VS removal were large tumor size, irregular tumor surface, and severe preoperative hydrocephalus. Patients with a longer symptom duration prior to surgery, those with polycyclic tumors, or with inhomogeneous VS, were at heightened risk for the development of CSF leaks. The general and functional outcome of surgery showed no correlation to the presence of preoperative hydrocephalus.

Conclusions

Primary tumor removal is the optimum management of disease in patients with VS with associated hydrocephalus; it leads to resolution of the hydrocephalus in the majority of cases, and the outcome is similar to that of patients without hydrocephalus. Certain factors may aid in identifying patients at risk for developing persistent hydrocephalus as well as those at risk for CSF leaks.