Large Acoustic Neuromas Research Articles

Impact of extent of internal acoustic meatus tumor removal using translabyrinthine approach for acoustic neuroma surgery

Many studies have investigated the surgical outcome and predictive factors of acoustic neuroma using different approaches. The present study focused on large tumors due to the greater likelihood of internal acoustic meatus involvement and the greater application of surgical intervention than radiosurgery. There have been no previous reports on outcomes of internal acoustic meatus tumor removal. We investigated the impact of the extent of internal acoustic meatus tumor removal using a translabyrinthine approach for large acoustic neuroma surgery and predictive factors of tumor control. This retrospective study reviewed 104 patients with large cerebellopontine angle tumor >3 cm treated by translabyrinthine approach microsurgery. Predictive factors of postoperative facial palsy, tumor control, and extent of internal acoustic meatus tumor removal were assessed. The mean tumor size was 38.95 ± 6.83 mm. Postoperative facial function showed 76.9% acceptable function (House-Brackmann grade 1 or 2) six months after surgery. The extent of internal acoustic meatus tumor removal was a statistically significant predictor factor of poor postoperative facial function. Younger age, larger tumor size needing radiosurgery, and more extensive removal of tumor were associated with better tumor control. More extensive internal acoustic meatus tumor removal was associated with poor postoperative facial function and better tumor control.

Multimodal Approach for Maximizing Facial Nerve Reservation in Large Acoustic Neuroma Surgery

Multimodal Approach for Maximizing Facial Nerve Reservation in Large Acoustic Neuroma Surgery

Translabyrinthine Approach for Resection of Large Cystic Acoustic Neuroma: Operative Video and Technical Nuances of Subperineural Dissection for Facial Nerve Preservation.

The translabyrinthine approach is advantageous for the resection of large acoustic neuromas compressing the brainstem when hearing loss is nonserviceable. This approach provides wide access through the presigmoid corridor without prolonged cerebellar retraction. Early identification of the facial nerve at the fundus is also achieved. In this operative video atlas manuscript, the authors demonstrate a step-by-step technique for microsurgical resection of a large cystic acoustic neuroma via a translabyrinthine approach. The nuances of microsurgical and skull base technique are illustrated including performing extracapsular dissection of the tumor while maintaining a subperineural plane of dissection to preserve the facial nerve. This strategy maximizes the extent of removal while preserving facial nerve function. A microscopic remnant of tumor was left adherent to the perineurium. A near-total resection of the tumor was achieved and the facial nerve stimulated briskly at low thresholds. Other than preexisting hearing loss, the patient was neurologically intact with normal facial nerve function postoperatively. In summary, the translabyrinthine approach and the use of subperineural dissection are important strategies in the armamentarium for surgical management of large acoustic neuromas while preserving facial nerve function. The link to the video can be found at: https://youtu.be/zld2cSP8fb8 .

Application of transcranial electrical stimulation-facial nerve motor evoked potentials in resection of large acoustic neuromas

Objective To discuss the role of transcranial electrical stimulation facial nerve motor evoked potentials (TCE-FNMEP) in resection of large acoustic neuromas. Methods In a retrospective clinical study, 58 patients with large acoustic neuroma were investigated at Department of Neurosurgery, Tianjin HuanHu Hospital form July 2016 to March 2017.All patients were investigated by facial nerve motor evoked potentials elicited by multi-pulse transcranial electrical motor cortex stimulation. For recording, the same electrode set-up was used as for continuous EMG (electromyogram) monitoring of the orbicularis oculi, oris muscles and mentalis. Pre-surgical (dura opening), intraoperative and post-surgical (dura closing) TCE-FNMEP amplitudes and latencies were documented. End (dura closing) to start (dura opening) amplitude ratios were compared to early-term (1 day post surgery) facial nerve function by House-Brackmann (H-B) grading. Results Fifty-one (87.9%, 51/58) patients obtained total tumor resection and 7 (12.1%, 7/58) achieved subtotal resection. All patients had anatomical preservation of facial nerves. There was no death in this series. Reliable TCE-FNMEPs were obtained in all patients. At 1 day post operation, 48 out of 58 case were graded as H-B Ⅰ-Ⅱ, the range of TCE-FNMEP amplitude ratio was 47.6%-100.0%, and the median was 85.4%. Five cases were graded as H-B Ⅲ, the range of TCE-FNMEP amplitude ratio was 43.2%-55.8%, and the median was 45.4%. Three cases were graded as H-B Ⅳ, the range of TCE-FNMEP amplitude ratio was 31.4%-53.2%, and the median was 33.6%. Two cases were graded as H-B Ⅴ-Ⅵ, the range of TCE-FNMEP amplitude ratio was 6.1% and 11.3%, respectively. There was a negative correlation between TCE-FNMEP amplitude ratio and early post-surgical HB grading (r=-0.611, P<0.01). Conclusion TCE-FNMEP seems to be highly reliable in predicting early postoperative facial function in resection of large acoustic neuromas and could be a valid protection technique of facial nerve. Key words: Neuroma, acoustic; Facial nerve; Evoked potentials, motor; Transcranial electrical stimulation

Microsurgical Resection of Large and Giant Acoustic Neuromas: A Focus on Facial Nerve Outcomes and Complications

Microsurgical Resection of Large and Giant Acoustic Neuromas: A Focus on Facial Nerve Outcomes and Complications

Management of a large acoustic neuroma involving brain-stem, inner, medium and external ear

Management of a large acoustic neuroma involving brain-stem, inner, medium and external ear

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.

Tactics of Surgical Treatment of Large and Giant Acoustic Neuroma

Introduction: Surgical treatment of large and giant acoustic neuromas (>3 cm) remains a challenge, especially when their radical removal, as involvement in neurovascular structures, may lead to unsatisfactory results and a lower quality of life for patients. A judicious combination of surgical excision is followed by observation and ability to use modern methods of radiation therapy to reduce the risk of mortality, postoperative complications, and to maintain a decent quality of life without compromising the radical treatment.

Underlay hourglass-shaped autologous pericranium duraplasty in "key-hole" retrosigmoid approach surgery: Technical report.

Background:Cerebrospinal fluid (CSF) leakages represent a major complication of skull base surgery. Watertight dural suture is challenging, and different ways to reinforce it have been proposed. Since 6 months, we use locally harvested autologous pericranium graft for dural repair in retrosigmoid approach.Methods:Retrospectively, we analyzed 27 patients operated on with key-hole retrosigmoid approach from May 2014. In all, autologous pericranium was harvested and inserted as an underlay “hourglass-shaped” plug under the dura plane and stitched to dura. Surgical patch and sealant were used for augmentation. Complications considered were new neurological symptoms, surgical site infections, meningitis, CSF-leaks, and pseudomeningocele.Results:Indications included tumor (16 cases), microvascular decompression (10 cases), and hemorrhagic cerebellar arteriovenous malformation (1 case). Surgical site infections, meningitis, and CSF leaks have never been observed. One neurofibromatosis type 2 patient operated on for large acoustic neuroma developed an asymptomatic pseudomeningocele, disappeared on 3-month magnetic resonance imaging follow-up.Conclusions:In our series, autologous pericranium inserted and stitched as an underlay hourglass-shaped plug, augmented with surgical patch pieces and dural sealant seemed to be safe and effective for dural repair in “key-hole” retrosigmoid approach. With this technique, we obtained low complication rate, similar to the best current results of available literature.

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

Patients with large vestibular schwannomas are at high risk of poor facial nerve (cranial nerve VII [CNVII]) function after surgery. Subtotal resection potentially offers better outcome, but may lead to higher tumor regrowth. To assess long-term CNVII function and tumor regrowth in patients with large vestibular schwannomas. Prospective multicenter nonrandomized cohort study of patients with vestibular schwannoma ≥2.5 cm who received gross total resection, near total resection, or subtotal resection. Patients received radiation if tumor remnant showed signs of regrowth. Seventy-three patients had adequate follow-up with mean tumor diameter of 3.33 cm. Twelve received gross total resection, 22 near total resection, and 39 subtotal resection. Fourteen (21%) remnant tumors continued to grow, of which 11 received radiation, 1 had repeat surgery, and 2 no treatment. Four of the postradiation remnants (36%) required surgical salvage. Tumor regrowth was related to non-cystic nature, larger residual tumor, and subtotal resection. Regrowth was 3 times as likely with subtotal resection compared to gross total resection and near total resection. Good CNVII function was achieved in 67% immediately and 81% at 1-year. Better immediate nerve function was associated with smaller preoperative tumor size and percentage of tumor left behind on magnetic resonance image. Degree of resection defined by surgeon and preoperative tumor size showed weak trend toward better late CNVII function. Likelihood of tumor regrowth was 3 times higher in subtotal resection compared to gross total resection and near total resection groups. Rate of radiation control of growing remnants was suboptimal. Better immediate but not late CNVII outcome was associated with smaller tumors and larger tumor remnants. CNVII, cranial nerve VIIGTR, gross total resectionHB, House-BrackmannMRI, magnetic resonance imageNTR, near total resectionSTR, subtotal resection.

Does the Presence of Cystic Change Alter the Facial Nerve Prognosis in Surgically Treated Large Acoustic Neuromas?

Does the Presence of Cystic Change Alter the Facial Nerve Prognosis in Surgically Treated Large Acoustic Neuromas?

Trigeminal nerve deficit in large and compressive acoustic neuromas and its correlation with MRI findings.

Evaluate the prevalence of preoperative trigeminal nerve deficit in large/compressive acoustic neuromas and try to find a correlation between pre/postoperative magnetic resonance imaging (MRI) findings and pre/postoperative trigeminal nerve deficit. Case series with chart review. University medical center. Retrospective study (1994-2009) including patients with stage 4 or 5 acoustic neuromas (Zini-Magnan classification). All patients underwent surgical resection. Pre- and postoperative trigeminal symptoms were sought. Imaging criteria were sought on pre- and 3-month postoperative MRI scans. Pearson χ(2) statistical test was used. Fifty-three patients (27 females, mean 51 years) were operated on. Preoperatively, 3 patients (5.7%) had trigeminal neuralgia, 1 (1.9%) trigeminal anesthesia, and 28 (52.8%) trigeminal hypoesthesia. Sixteen patients (30.2%) had no corneal reflex (ophthalmic branch); keratitis occurred in 1 patient (1.9%). Postoperatively, 2 patients (3.8%) had trigeminal neuralgia, 1 (1.9%) trigeminal anesthesia, and 24 (45.3%) trigeminal hypoesthesia. Twenty-six patients (49%) had no corneal reflex; keratitis occurred in 11 patients (20.7%). Preoperative trigeminal hypoesthesia was statistically correlated with impaction of the tumor on cerebellar peduncles on preoperative MRI. Postoperative trigeminal hypoesthesia was statistically correlated with nonvisibility of the trigeminal nerve on postoperative MRI. In large/compressive acoustic neuromas, trigeminal nerve deficit has to be sought to avoid corneal complications in particular. Trigeminal hypoesthesia occurs preoperatively in about half of the cases. It remains relatively stable after tumor removal, but there appears to be an increased rate of absent corneal reflex and keratitis postoperatively. We were able to correlate pre/postoperative trigeminal hypoesthesia with pre/postoperative MRI findings.

Analysis of surgical outcomes in large acoustic neuroma

To analyze the surgical outcomes and share experience in the surgical management of acoustic neuroma(AN). A retrospective review was performed in 134 patients with sporadic large ANs operated from Jan. 2001 to Dec. 2012. The patients' information, tumor size, tumor cystic degeneration, surgical approach, intraoperative anatomical facial nerve integrity rate, postoperative facial nerve function and complications were recorded. There were one hundred and twenty-nine patients (96.3%) received surgeries within one month after first diagnosis of vestibular schwannoma(VS) or definite diagnosis of recurrence.Five patients (3.7%) hesitated to be operated until tumor was found to be growing on MRI during the follow-up. The average tumor diameter was about (40.9 ± 6.8) mm (31.0-70.0 mm). The cystic tumor percentage arrived at 35.1% (47/134). The surgical approaches included 118(88.1%) translabyrinthine approaches, comprising 16(11.9%) modified enlarged translabyrinthine approaches, and 16 (11.9%) transaortic approaches. Total, near total, and subtotal tumor removal rate was 91.0% (122/134), 6.7% (9/134) and 2.2% (3/134), respectively. The anatomical facial nerve integrity was preserved in 88.8% (19/134) of all patients. And it was significantly lower in cystic VS (80.9% vs 93.1%, P = 0.044). There were 32.3% (43/133) and 36.8% (49/133) of patients had a good postoperative facial nerve function in short-term (discharge from hospital) and long-term (1 year) follow-up, respectively.General rate of complications was 17.9% (24/134). CSF leakage occurred in 7.5% of patients. Mortality rate was 0.7% (1/134). Follow-up time ranged from 1 to 5 years, average time was(2.7 ± 0.4)years.Four cases occurred recurrence. Major management strategy of large AN is surgical resection.Even for those who had temporary antagonism for surgery, the wait and scan policy is necessary. Although the tumor removal is safe and accompanies extremely low mortality and incidence of complication, the patient with large AN must be informed in detail about the possible surgical risks. The tumor cystic degeneration is an important crucial factor which influences the surgical outcomes of AN, especially in postoperative facial nerve function.

Retractorless translabyrinthine approach for resection of a large acoustic neuroma: operative video and technical nuances

Large acoustic neuromas, greater than 3 cm, can be technically challenging tumors to remove because of their intimate relationship with the brainstem and surrounding cranial nerves. Successful tumor resection involves functional preservation of the facial nerve and neurovascular structures. The translabyrinthine approach is useful for surgical resection of acoustic neuromas of various sizes in patients with poor preoperative hearing. The presigmoid surgical corridor allows direct exposure of the tumor in the cerebellopontine angle without any fixed cerebellar retraction. Early identification of the facial nerve at the fundus facilitates facial nerve preservation. Large acoustic tumors can be readily removed with a retractorless translabyrinthine approach using dynamic mobilization of the sigmoid sinus. In this operative video atlas report, the authors demonstrate their operative nuances for resection of a large acoustic neuroma via a translabyrinthine approach using a retractorless technique. Facial nerve preservation is achieved by maintaining a plane of dissection between the tumor capsule and the tumor arachnoid so that a layer of arachnoid protects the blood supply to the facial nerve. Multilayered closure is achieved with a fascial sling technique in which an autologous fascia lata graft is sutured to the dural defect to suspend the fat graft in the mastoidectomy defect. We describe the step-by-step technique and illustrate the operative nuances and surgical pearls to safely and efficiently perform the retractorless translabyrinthine approach, tumor resection, facial nerve preservation, and multi-layered reconstruction of the skull base dural defect to prevent postoperative cerebrospinal fluid leakage. The video can be found here: http://youtu.be/ros98UxqVMw .

Trigeminal Nerve Deficit in Large/Compressive Acoustic Neuromas (ANs) and Its Correlation with MRI Findings

Objectives: Evaluate the risk of pre- and postoperative trigeminal nerve (V) impairment in large ANs. Determine predictive risk factors on pre- and postoperative MRIs. Methods: Retrospective study (1994-2009) including patients with stage 4 or 5 AN (classification of Zini-Magnan). All underwent surgical resection (chiefly translabyrinthine approach). Pre- and postoperative trigeminal symptoms were sought. Pre- and 3-month-postoperative MRIs were obtained. Results: Fifty-four patients (30 females, mean 51 years) were operated. Preoperatively, 3 patients (5.5%) had trigeminal neuralgia, 29 (54%) had trigeminal hypoesthesia (V1 &lt; V2 = V3), and 16 (30%) had no corneal reflex (V1 branch). Postoperatively, 2 patients (4%) had trigeminal neuralgia, 1 (2%) had trigeminal anesthesia, 25 (46%) had trigeminal hypoesthesia (V1 = V2 = V3), 26 (48%) had no corneal reflex, and most also had House-Brackmann ≥ grade IV facial paralysis. Keratitis occurred in 42% of patients with absent corneal reflex postoperatively. After analyzing preoperative MRI, there was only one predictive factor of preoperative trigeminal impairment: impaction of the tumor on cerebellar peduncles ( P &lt; 0.05). Postoperative trigeminal deficit was correlated with one finding on postoperative MRI: nonvisibility of V on MRI ( P &lt; 0.05). Postoperative trigeminal deficit was correlated with one finding on preoperative MRI: impaction of the tumor on cerebellar peduncles ( P &lt; 0.05). Conclusions: Trigeminal impairment in large/compressive ANs has to be sought particularly to avoid corneal complications. If the frequency of trigeminal hypoesthesia slightly diminishes after tumor removal, there is worsening of preoperative function of V1 and increased frequency of absent corneal reflex, also worsened by facial paralysis. We were able to correlate trigeminal involvement with pre- and postoperative MRI findings.

Improved Facial Nerve Outcomes Using an Evolving Treatment Method for Large Acoustic Neuromas

To describe a successful paradigm for the treatment of large acoustic neuromas (vestibular schwannomas). Retrospective case review. Tertiary referral center. The charts of 2,875 acoustic neuroma patients at Michigan Ear Institute were reviewed to identify 153 patients who underwent surgical resection for large acoustic neuromas (>=3 cm) between 2000 and 2009. Staged surgical resection or single stage surgery with or without adjuvant stereotactic radiosurgery. Postoperative facial nerve outcomes are reported using the House-Brackmann (HB) facial nerve grading scale and compared with historical controls from a literature review. Rates of adverse outcomes are also reported. Seventy-five patients underwent staged surgical resection of their tumors, whereas 78 patients underwent either single stage surgery or surgery with subsequent stereotactic radiosurgery. Eighty-one percent of patients in the staged surgical resection group had a postoperative HB Grade I or II facial nerve function compared with 75% in the single stage surgical group. Overall, 78% of patients in the current study had HB Grade I or II after treatment compared with a mean of 53% in the literature for similar sized tumors. Our methods including the decision to use staged surgery when necessary, dissection of tumor with stimulating dissector-directed intraoperative monitoring, and use of adjuvant stereotactic radiosurgery are described. Using the described paradigm, large acoustic neuromas can be successfully treated with either staged or single-stage surgical resection with or without adjuvant radiosurgery to obtain more favorable facial nerve outcomes than historically reported controls while minimizing morbidity for the patient.

Trigeminal Nerve Deficit in Large and Compressive Acoustic Neuromas (ANs) and Its Correlation with MRI Findings

Objectives: To evaluate the risk of pre- and postoperative trigeminal nerve (V) impairment in large ANs, and to determine predictive risk factors on pre- and postoperative MRIs.

Intraoperative electrophysiologic monitoring of the facial nerve in operation of large acoustic neuromas

Objective To explore intraoperative protection of facial nerve and evaluate its function after operation in large acoustic neuromas surgery by electrophysiologic monitoring. Method A total of 42 patients'clinical data with large acoustic neuromas between Jun, 2007 and Mar, 2010 were analyzed retrospectively,who were treated microsurgically with intraoperative electrophysiological monitoring in our department. Results The facial nerve was preserved anatomically in 37 patients (88％). The function of facial nerve was kept well in 30 cases (71％). Stimulative intensity of 1 ～ 3 V at the end of operation is related to the good function of facial nerve. The proximal - to - distal amplitude ratio of facial nerve after surgery less than 0. 3 presented with a bad facial function. ConclusionsIntraoperative monitoring has significantly decreased facial nerve morbidity in large acoustic neuromas surgery. Stimulative intensity at the exit of facial nerve from brainstem is related to the facial nerve function negatively. The proximal - to - distal amplitude ratio can predict the facial nerve function positively following acoustic neuromas resection. Key words: Neuromas, acoustic; Facial nerve; Electrophysiologic monitoring; Function evaluation

Intraoperative real-time continuous facial nerve monitoring in acoustic neuroma surgery

Dear Editor: We were very pleased to read the letter to the editor from Acioly et al. They estimated the intraoperative continuous monitoring of evoked facial nerve electromyograms we reported [1] as "a new device for an old concept," and we agree with their assessment. Because the first step for starting continuous monitoring of the facial nerve is to identify the root exit zone (REZ), the authors expressed concern about a case in which a large acoustic neuroma obstructed the REZ of the facial nerve because of anatomical distortion of the brainstem. In Kohno's experience, there have been only four cases (0.7%) out of 550 surgically treated patients with acoustic neuromas, in which he could not identify the REZ of the facial nerve, a very low percentage despite the fact that large tumors (Koos 3 and 4) account for 84% of cases. For a large tumor, internal decompression of the tumor is necessary to find the REZ of the facial nerve. Until we start continuous monitoring, we can notice that the facial nerve is mechanically stimulated by the free-running spontaneous facial electromyography. Therefore, we do not consider the possibility of facial nerve impairment before starting continuous monitoring. An important part of developing new surgical methodologies is to keep them simple, effective and easy to perform. For a new method to become popular and widely used over time, however, certain techniques and tips are required for every operation in the neurosurgical field. In particular with acoustic neuroma surgery, all neurosurgeons know that individual technique and experience must be considered. The authors express concern about movement of the electrode for continuous stimulation; however, we actually replace it at most twice or three times in a surgery, with minimum adjustment within a minute. To be sure, there are tips for stabilizing the electrode to prevent movement. As we described in our paper, we use a small cotton pad to fix the electrode in place. The authors also refer to the necessity of placing recording needle electrodes on three muscles (frontalis, orbicularis oculi and oris). Actually, electromyograms from three muscles vary in initial voltages and intraoperative changes, and there is the possibility that problems with a needle electrode or an electrical cord might occur. Therefore, we believe that setting recording electrodes on all of these three muscles is effective and necessary. The monitoring by transcranial facial motor-evoked potentials (FMEP), which is recommended by Alcioly et al., is surely effective, particularly until the surgeon finds the REZ of the facial nerve. However, body movement at electrical stimulation is considered a problem. In FMEP, as they point out, it is necessary to stop microsurgical procedures to record electromyograms from the viewpoint of safety. We consider FMEP to be a different type of monitoring compared to our method, which allows us to assess the condition of the facial nerve continuously during the process of dissecting the tumor from the facial nerve in real-time without stopping microsurgical procedures. M. Kohno (*) Department of Neurosurgery & Stroke Center, Tokyo Metropolitan Police Hospital, 4-22-1, Nakano, Nakano-Ku, Tokyo 164-0001, Japan e-mail: mkouno-nsu@umin.ac.jp

Long-term facial nerve function evaluation following surgery for large acoustic neuromas via retrosigmoid transmeatal approach

By evaluating the postoperative facial nerve function of large acoustic neuromas, the purpose of this study was to analyze the factors that influence the facial nerve function outcome and to explore the surgical strategy for large acoustic neuromas. A retrospective study of surgical outcome was performed on 89 patients with large acoustic neuromas. All operations were performed via the retrosigmoid transmeatal approach using the intraoperative electrophysiological monitoring. Gross total resection was performed in 38 (42.7%) of the 89 patients, near total resection in 35 (39.3%), and subtotal resection in 16 (18.0%). The facial nerve was anatomically intact at the end of surgery in 83 (93.3%) patients. At 1year after surgery, 48 (53.9%) patients had good facial nerve function (House-Brackmann (HB) Grades I-II), 23 (25.8%) patients had regular facial nerve function (HB Grades III-IV), and 18 (20.2%) patients had poor facial nerve function (HB Grades V-VI). For large acoustic neuromas, the goal of complete tumor resection and preservation of acceptable facial nerve function can be attained via the retrosigmoid transmeatal approach, using the intraoperative facial nerve monitoring. The surgical strategy of near total resection is indicated for the large acoustic neuromas with severe adherence or inclusion in order to preserve facial nerve function.