Hearing preservation after complete microsurgical removal in vestibular schwannomas

Endoscopic retrosigmoid trans-petrosal fissure approach for vestibular schwannomas: case series

The management of vestibular schwannoma (VS) remains one of the most formidable challenges in neurosurgery owing to the eloquent nature of surrounding anatomy. Although endoscopy-assisted microsurgery has recently gained momentum in cerebellopontine angle region surgery, the feasibility of pure endoscopic technique has been rarely reported. Here we present the operative technique and preliminary outcomes of fully endoscopic retrosigmoid trans-petrosal fissure approach (ER-TPFA) for VS surgery. Clinical data of 36 consecutive cases of VS treated with the ER-TPFA from March 2021 to March 2023 were analyzed. The patients were placed in a modified lateral park-bench position, with the Dandy incision and suboccipital craniotomy performed. With the endoscopic holder, endoscopic procedures were performed using standard two-hand microsurgical techniques by one surgeon. Arachnoidal dissection of the petrosal fissure was performed for identifying the brainstem end of facial nerve and separating the tumor from the cerebellum, without brain retraction seen in traditional microsurgical technique. The tumors had an averaged size of 3.0 cm in diameter. According to the Hannover classification, nearly all the tumors were grade III-IV (97.3%). Using ER-TPFA, 33 patients (91.7%) achieved gross total resection. Anatomic preservation of the facial nerve was achieved in 35 cases, with 33 patients (91.7%) retaining a House-Brackmann score of 1-2 postoperatively. Four out of ten patients still had serviceable hearing 6 months after operation. Postoperatively, there was no post-craniotomy hematoma, cerebellar edema, and new-onset cerebellar ataxia. With a better visualization of the cerebellopontine angle region, ER-TPFA may help preserve facial nerve function and maintain high gross total resection rate while minimizing complications. We believe this retractorless technique can be a safe and effective alternative for the management of VS with satisfactory clinical results.

Monitoring Cochlear Nerve Action Potential for Hearing Preservation in Medium/Large Vestibular Schwannoma Surgery: Tips and Pitfalls

The diagnosis of large vestibular schwannomas (VS) with retained useful hearing has become increasingly common. Preservation of facial nerve (FN) function has improved using intraoperative EMG monitoring, hearing preservation remains challenging, with the recent use of cochlear nerve action potential (CNAP) monitoring. This prospective longitudinal series of VS with useful hearing operated on using a retrosigmoid approach included 37 patients with a mean largest extrameatal VS. diameter of 25 ± 8.7 mm (81% of Koos stage 4). CNAP was detected in 51% of patients, while auditory brainstem responses (ABR) were present in 22%. Patients were divided into two groups based on the initial intraoperative CNAP status, whether it was present or absent. FN function was preserved (grade I-II) in 95% of cases at 6 months. Serviceable hearing (class A + B) was preserved in 16% of the cases, while 27% retained hearing with intelligibility (class A-C). Hearing with intelligibility (class A-C) was preserved in 42% of cases when CNAP could be monitored in the early stages of VS resection versus 11% when it was initially absent. Changes in both the approach to the cochlear nerve and VS resection are mandatory in preserving CNAP and improve the rate of hearing preservation.

Impact of Vestibular and Balance Rehabilitation Therapy Along With Conventional Physiotherapy in a Case of Vestibular Schwannoma With CP Angle Tumor: A Case Report

Vestibular Schwannoma forms in Schwann cells which cover the vestibular nerve, often in the internal auditory canal. Symptoms were likely present before the excision of the tumor. After the excision of the tumor, symptoms may include, hearing defects, tinnitus, facial muscle abnormalities, headache, and balance impairments. This case report is of a female patient with vestibular schwannoma, who had a few above-mentioned symptoms after the surgery. Her physiotherapy protocol included Vestibular and Balance Rehabilitation Therapy along with Conventional Physiotherapy. Also, facial proprioceptive neuromuscular facilitation (PNF) was a part of her treatment. The outcome measures used to rule out the results were the motion sensitivity quotient (MSQ) and the Berg balance scale (BBS). Improvement of symptoms is likely related to the excision of the tumor and the therapy program. The person's balance and coordination improved as a result of the rehabilitation protocol, and she was able to do her regular tasks with minimal assistance. Her standard of living was also enhanced.

Endoscopic-assisted microsurgical resection of giant vestibular schwannoma in semi-sitting position

The main objectives of microsurgery for vestibular schwannoma are total tumor removal and preservation of facial and cochlear nerve function. For giant tumors, total tumor removal and facial nerve function preservation are challenging. The semisitting position has some advantages. In this video the authors show the removal of a giant vestibular schwannoma with the patient in a semisitting position. They demonstrate the advantages of the semisitting technique, such as the two-handed microsurgical dissection technique and a clear operative field. Finally, a small residual tumor in the internal auditory canal was removed by endoscopy. The patient's facial function was House-Brackmann grade I at discharge. The video can be found here: https://stream.cadmore.media/r10.3171/2021.7.FOCVID2176.

Outcomes after semisitting and lateral positioning in large vestibular schwannoma surgery: A single-center comparison

OBJECTIVE

The semisitting position (SSP) and lateral position (LP) in vestibular schwannoma (VS) surgery each have advantages and disadvantages, and which position is superior overall is debatable. Our objective was to determine the optimal position for surgical treatment of VSs with a diameter ≥3 cm.

METHODS

We retrospectively evaluated consecutive patients with a large VS treated between January 2010 and July 2020. Patients were grouped by surgical position and analyzed.

RESULTS

We enrolled 259 patients (LP group, n = 156; SSP group, n = 103). The resection extent was not significantly different between the SSP (gross-total resection [GTR], n = 89 [88.1%], near-total resection [NTR], n = 10 [9.9%], subtotal resection [STR], n = 2 [2.0%]) and LP (GTR, n = 125 [80.1%]; NTR, n = 24 [15.4%]; STR, n = 7 [4.5%]) groups. The rate of GTR with facial nerve (FN) functional preservation was higher in the SSP group than in the LP group (P = 0.014) at eight days after the operation. However, during follow-up (SSP group median, 31.5 months; LP group median, 19.5 months), there was no significant between-group difference in FN functional preservation. Two patients in the SSP group required conversion to the LP due to severe intraoperative venous air embolism (VAE).

CONCLUSION

Compared with the LP, the SSP did not produce significantly better FN outcomes in patients with a large VS. The duration of surgery was significantly longer in SSP cases than in LP cases. Given the risk of VAE associated with the SSP, the selection of the optimal surgical position should be made with caution on an individual basis.

Vestibular Schwannoma Surgery: Outcome and Complications in Lateral Decubitus Position versus Semi-sitting Position-A Personal Learning Curve in a Series of 544 Cases over 3 Decades

OBJECTIVE

To retrospectively evaluate influence of intraoperative positioning (semisitting vs. lateral decubitus) and surgeon's learning curve with regard to functional outcome of patients with vestibular schwannoma.

METHODS

This study included 544 patients (median age 57 years) and spanned 3 decades: 1991-1999 (n = 103), 2000-2009 (n = 210), and 2010-2019 (n = 231). Surgery was performed in the lateral decubitus position in 318 patients and the semisitting position in 163 patients. Large T3 and T4 tumors were present in 77% of patients.

RESULTS

Complete tumor removal was achieved in 94.3% of patients. A significant reduction in surgery duration and blood loss was observed over 3 decades for T3 (from 325 to 261 minutes, P < 0.001) and T4 (from 440 to 330 minutes, P < 0.001), but not for T1 and T2, tumors. The semisitting position diminished surgical time in T3 and T4 tumors by 1 more hour (P < 0.001). Over 3 decades, facial nerve outcome improved significantly from 59.8% House-Brackmann grade 1-2 in the first decade to 81.7% in the last decade (P < 0.001). Furthermore, hearing was preserved in 45.3%: 23.3% of patients in the first decade and 50.5% in the last decade (P = 0.03). However, neither facial nerve outcome nor hearing preservation significantly differed in patients operated on in the lateral decubitus versus the semisitting position. The most common complication was cerebrospinal fluid leak (6.1%) followed by hemorrhage (3.5%) and pulmonary embolism (2.2%).

CONCLUSIONS

Follow-up over 3 decades illustrates a learning curve with significantly improved results. While the semisitting position accelerates the procedure and is associated with reduced blood loss, it does not significantly influence functional outcome.

Retrosigmoid Approach in the Supine Position Using ORBEYE: A Consecutive Series of 14 Cases

One of the merits of recently introduced exoscopes, including ORBEYE, is that they are superior to a conventional microscope in terms of ergonomic features. Taking advantage of it, the retrosigmoid approach can be performed in the supine position using ORBEYE. We report a consecutive series of 14 operations through the retrosigmoid approach in the supine position using ORBEYE. Fourteen consecutive patients who underwent surgery through the retrosigmoid approach for cerebellopontine (CP) angle lesions in the supine position using ORBEYE were targeted, and surgical outcomes and complications were examined. We evaluated the posture of the operator and the surgical field during this approach compared with those using a conventional microscope. In all 14 cases, all operative procedures were accomplished only using the ORBEYE. There were no operative complications due to this approach. Using ORBEYE, even when the angle of the operative visual axis was horizontal, the operators could manipulate in a comfortable posture. They were not forced to be in an uncomfortable posture that extended their arms, as is often the case with a conventional microscope. Therefore, they could use shorter surgical instruments. As the cerebellum shifted downward with gravity even using slight retraction during this approach, the working space of the surgical field was easily secured. Through this approach, the operators can perform stable microsurgery of CP angle lesions in a comfortable posture. This approach can reduce the burden on the operator and the patient, leading to a refined surgical procedure.

The French Cochlear Implant Registry (EPIIC): Cochlear implant candidacy assessment of off-label indications

OBJECTIVE

Evaluate in France the outcomes of cochlear implantation outside the selection criteria, off-label.

MATERIAL AND METHODS

This is a prospective cohort study including adults and children having received a cochlear implant (CI) in an off-label indication, that is outside the criteria established by the "Haute Autorité de santé (HAS)" in 2012. The data was collected from the "EPIIC" registry on recipients who received CIs in France between 2011 and 2014. Speech audiometry was performed at 60dB preimplantation and after one year of CI use, as well as an evaluation of the scores of the quality of life with the APHAB questionnaire, the scores for CAP and the professional/academic status in pre- and post-implantation conditions. Major and minor complications at surgery have been recorded.

RESULTS

In total, 590 patients (447 adults and 143 children) with an off-label indication for CIs were included in this study from the EPIIC registry (11.7% of the whole cohort of EPIIC). For adults, the median percentage of comprehension using monosyllabic word lists was 41% in preimplantation condition versus 53% after one year of CI use (P<0.001) and 60% versus 71% in dissyllabic word lists (P<0.001). The CAP scores were 5 versus 6 in pre- and post-implantation conditions respectively (P<0.001) and the APHAB scores were statistically lower after implantation (P<0.001). In the children cohort, the median percentage of comprehension using monosyllabic word lists was 51% in preimplantation condition and 65% after CI (P<0.001), and 48% versus 82% (P<0.001) for dissyllabic word lists. The CAP scores were 5 versus 7 respectively in pre- and post-CI conditions (P<0.001). Thirty-two minor complications (5.4%) and 17 major complications (2.8%) were reported in our panel of off-label indication patients.

CONCLUSION

These results suggest that a revision of the cochlear implantation candidacy criteria is necessary to allow more patients with severe or asymmetric hearing loss to benefit from a CI when there is an impact on quality of life despite the use of an optimal hearing aid.

Prognostic Significance of Preoperative Geometric Changes in the Internal Acoustic Canal for Hearing Preservation in Vestibular Schwannoma Surgery

OBJECTIVE

This study focused on the changes in the internal acoustic canal (IAC) caused by vestibular schwannomas (VSs) and their prognostic significance for postoperative hearing outcome.

METHODS

A total of 125 consecutive cases of VS were included. We used a neuronavigation software to perform the following measurements on both the tumor side and healthy side: volume of the IAC (VIAC), maximal diameter of the IAC (DIAC), and length of the IAC (LIAC). A statistical analysis was realized using Spearman correlation to test the correlation of the morphometric measure of the IAC and postoperative hearing. Multivariate analysis was performed to test the impact of measurements of the IAC and preoperative hearing on postoperative hearing.

RESULTS

The mean VIAC on the tumor side and on the healthy side was 0.271 and 0.169 cm³, respectively. The mean DIAC was 9.438 mm on the tumor side and 7.034 mm contralateral. The correlations tests showed significant correlations of both postoperative hearing deficit and degree of hearing loss with 1) VIAC on the tumor side, 2) difference between VIAC on the tumor side and healthy side, 3) DIAC on the tumor side, and 4) difference between the DIAC on the tumor side and healthy side. The multivariate analysis showed significant impact of the DIAC (P = 0.01) and preoperative hearing status (P = 0.02) on postoperative hearing.

CONCLUSIONS

Enlargement of the VIAC and DIAC are negative prognostic factors for hearing preservation. Reasons may be long-standing compression of the auditory nerve and an increased vulnerability of the inner ear structures during the drilling of the IAC.

Long-term outcome after Gamma Knife radiosurgery for acoustic neuroma of all Koos grades: a single-center study

OBJECTIVE

The authors present long-term follow-up data on patients treated with Gamma Knife radiosurgery (GKRS) for acoustic neuroma.

METHODS

Six hundred eighteen patients were radiosurgically treated for acoustic neuroma between 1992 and 2016 at the Department of Neurosurgery, Medical University Vienna. Patients with neurofibromatosis and patients treated too recently to attain 1 year of follow-up were excluded from this retrospective study. Thus, data on 557 patients with spontaneous acoustic neuroma of any Koos grade are presented, as are long-term follow-up data on 426 patients with a minimum follow-up of 2 years. Patients were assessed according to the Gardner-Robertson (GR) hearing scale and the House-Brackmann facial nerve function scale, both prior to GKRS and at the times of follow-up.

RESULTS

Four hundred fifty-two patients (81%) were treated with radiosurgery alone and 105 patients (19%) with combined microsurgery-radiosurgery. While the combined treatment was especially favored before 2002, the percentage of cases treated with radiosurgery alone has significantly increased since then. The overall complication rate after GKRS was low and has declined significantly in the last decade. The risk of developing hydrocephalus after GKRS increased with tumor size. One case (0.2%) of malignant transformation after GKRS was diagnosed. Radiological tumor control rates of 92%, 91%, and 91% at 5, 10, and 15 years after GKRS, regardless of the Koos grade or pretreatment, were observed. The overall tumor control rate without the need for additional treatment was even higher at 98%. At the last follow-up, functional hearing was preserved in 55% of patients who had been classified with GR hearing class I or II prior to GKRS. Hearing preservation rates of 53%, 34%, and 34% at 5, 10, and 15 years after GKRS were observed. The multivariate regression model revealed that the GR hearing class prior to GKRS and the median dose to the cochlea were independent predictors of the GR class at follow-up.

CONCLUSIONS

In small to medium-sized spontaneous acoustic neuromas, radiosurgery should be recognized as the primary treatment at an early stage. Although minimizing the cochlear dose seems beneficial for hearing preservation, the authors, like others before, do not recommend undertreating intracanalicular tumors in favor of low cochlear doses. For larger acoustic neuromas, radiosurgery remains a reliable management option with tumor control rates similar to those for smaller acoustic neuromas; however, careful patient selection and counseling are recommended given the higher risk of side effects. Microsurgery must be considered in acoustic neuromas with significant brainstem compression or hydrocephalus.

Simultaneous cochlear implantation as a therapeutic option in vestibular schwannoma surgery: case report

Hearing loss is the most common symptom of vestibular schwannomas (VSs). The management of these lesions includes observation, radiosurgery, and microsurgical resection. Hearing preservation and rehabilitation are the major challenges after the tumor treatment. A 43-year-old man with previous left-sided profound hearing loss and tinnitus presented with a 2-mm left-sided intracanalicular VS. The decision was made to perform a simultaneous cochlear implantation (CI) and microsurgical resection of the tumor. The patient did well postoperatively, with significant improvement of tinnitus, sound localization, and speech recognition in noise. Previous reports of simultaneous CI and VS resection in patients with neurofibromatosis type 2 and sporadic VS in the only hearing ear have been described. The role of CI in patients with VS and normal contralateral hearing has been recently described, showing positive outcomes due to the binaural benefits. Tinnitus also can be treated by the implantation of the cochlear device. The simultaneous microsurgical removal of VS and implantation of a cochlear device is a feasible approach in patients with unilateral hearing loss and severe tinnitus.

A systematic review about the position-related complications of acoustic neuroma surgery via suboccipital retrosigmoid approach: Sitting versus lateral

This systematic review wasdesigned to compare the complications of acoustic neuroma surgery via the suboccipital retrosigmoid approach in the sitting versus lateral positions. Searches for randomized trials and observational studies about the complications of acoustic neuroma surgery were performed in five medical databases (though October 2015) including PubMed, MEDLINE (In-Process and Other Non-Indexed Citations), EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL) and PsycINFO. Primary outcomes in this study were venous air emboli, neuropsychological defects, CSF leak, facial and abducens nerves palsy, postoperative deafness, hydrocephalus and mortality. Secondary outcomes were total tumor removal, facial and cochlear nerves preservation and ataxia. 843 abstracts and titles were reviewed and 10 studies (two non-randomized comparative studies and 8 non-comparative case series) were included for data extraction. Because of the heterogeneity of the studies, small number of participants and methodological shortcomings, findings were evaluated qualitatively. No impressive advantage was found in surgical or neurological outcomes for use of the sitting or lateral positions in patients with acoustic neuroma surgery. According to the available evidence, it seems that both sitting and lateral positions can be used with an equivalent safety for acoustic neuroma surgery via the retrosigmoid suboccipital approach. There seems a clear need for comparative studies to compare harms and other outcomes for these two positions.

Summary and consensus in 7th International Conference on acoustic neuroma: An update for the management of sporadic acoustic neuromas

Sporadic vestibular schwannoma (acoustic neuroma) is a benign tumor arising from cochleovestibular nerve. Nowadays, various specialties and medical centers are treating this disease, and the multidisciplinary collaboration is the trend. In an effort to promote a uniform standard for reporting clinical results, even for treatment indications, the mainly controversies were posed and discussed during the 7th International Conference on acoustic neuroma, and the agreement was summarized by the Committee of this conference. The main symptoms grading and tumor stage should note its name of classification for making them comparable. The goal of the modern managements for vestibular schwannoma is to improve the quality of life with lower mortality, lower morbidity and better neurological function preservation. The experience of surgical team and their preference might be a major factor for the outcome. Because of lacking of long-term follow-up large data after radiotherapy, and with the development of microsurgery, radiotherapy is now less recommended except for recurrent cases or elderly patients.

A New Method of Directing Endoscope Pathway in Single-Nostril Transpheoidal Approach for Safety by Using Volume Rendering With Thin-Section Computed Tomographic Image

OBJECTIVE

This study aims to locate important structures surrounding the sella node and measure the distances and angles between signalized points by using both three-dimensional reconstruction technique and volume-rendering. These distances and angles can provide more accurate reference for surgeries in pituitary adenomas.

METHODS

Ninty volunteers' skulls were scanned and thin-section computed tomographic images were displayed. The highest point of saddle node on double sides were marked as point A (right) and A1 (left), the highest point of posterior Clinton process on double side as B (right) and B1 (left). And the point of alas minor ossis sphenoridalis with sohenoidal creast was marked as point O. For the latter can not been distinguished in images, point O was used to replace the anterior nasal spine, which can accurately locate the median sagittal plane. The result of three-dimensional reconstruction is used to measure the distance between O and A, A1, B, B1 and angles between OA, OA1, OB, OB1 and their projection line on the standard horizontal plane (α, α1, β, β1). Analyzing the difference by examining the significance difference between both sides can also help the authors to determine whether there is a symmetric difference.

RESULTS

The distance of OA was measured as 23.2 (6.5) mm [range, 11.2-45.2 mm; 95% confidence interval (CI), 21.9-24.4 mm]. The distance of OA1 was measured as 23.4 (5.7) mm (range, 9.9-47.2 mm; 95% CI, 22.2-24.6 mm). The distance of OB was measured as 31.1 (5.5) mm (range, 17.8-45.2 mm; 95% CI, 30.0-32.2 mm). The distance of OB1 was measured as 31.2 (6.0) mm (range, 10.1-47.8 mm; 95% CI, 30.0-32.5 mm). The angle of α was measured as 81.1 (10.0)° (range, 60-137.5°, 95% CI, 79.0-83.2°). The angle of α1 was measured as 81.3 (8.5)° (range, 60-97.4°, 95% CI, 79.5-83.1°). The angle of β was measured as 91.5 (5.2)° (range, 74.9-102.2°, 95% CI, 90.5-92.6°). The angle of β1 was measured as 91.0 (6.6)° (range, 74.7-104.7°, 95% CI, 89.2-92.0°).

CONCLUSIONS

The above results can facilitate the location of these structures and minimize surgical trauma to optic chiasm and carotid artery surrounding. The method is especially effective in promising more secure and accurate direction to guide surgeons during surgeries in pituitary adenomas.

Hearing Outcomes After Stereotactic Radiosurgery for Vestibular Schwannomas : Mechanism of Hearing Loss and How to Preserve Hearing

The use of stereotactic radiosurgery (SRS) expanded to include the treatment of vestibular schwannomas (VSs) in 1969; since then, efforts to increase tumour control and to reduce cranial neuropathy have continued. Using the currently recommended marginal dose of 12-13 Gy, long-term reported outcomes after SRS include not only excellent tumour control rates of 92-100 % but also outstanding functional preservation of the trigeminal and facial nerves, with values of 92-100 % and 94-100 %, respectively. Nonetheless, hearing preservation remains in the range of 32-81 %. Previous studies have suggested possible prognostic factors of hearing preservation such as the Gardner-Robertson grade, radiation dose to the cochlea, transient volume expansion (TVE) after SRS, length of irradiated cochlear nerve, marginal dose to the tumour, and age. However, we still do not clearly understand why patients lose their hearing after SRS for VS.Relevant to these considerations, one study recently reported that the auditory brainstem response (ABR) wave V latency and waves I and V interval (IL_I-V) correlated well with intracanalicular pressure values and even with hearing level. The demonstration that ABR values, especially wave V latency and IL_I-V, correlate well with intracanalicular pressure suggests that patients with previously elevated intracanalicular pressure might have an increased chance of hearing loss on development of TVE, which has been recognised as a common phenomenon after SRS or stereotactic radiotherapy (SRT) for intracranial schwannomas.In our experience, the ABR IL_I-V increased during the first 12 months after SRS for VSs in patients who lost their serviceable hearing. The effect of increased ABR IL_I-V on hearing outcome also became significant over time, especially at 12 months after SRS, and was more prominent in patients with poor initial pure-tone average (PTA) and/or ABR values. We hypothesise that patients with considerable intracanalicular pressure at the time of SRS are prone to lose their serviceable hearing due to the added intracanalicular pressure induced by TVE, which usually occurs within the first 12 months after SRS for VSs. Using these findings, we suggested a classification system for the prediction of hearing outcomes after SRS for VSs. This classification system could be useful in the proper selection of management modalities for hearing preservation, especially in patients with only hearing ear schwannoma or neurofibromatosis type 2.Advances in diagnostic tools, treatment modalities, and optimisation of radiosurgical dose have improved clinical outcomes, including tumour control and cranial neuropathies, in patients with VSs. However, the preservation of hearing function still falls short of our expectation. A prediction model for hearing preservation after each treatment modality will guide the proper selection of treatment modalities and permit the appropriate timing of active treatment, which will lead to the preservation of hearing function in patients with VSs.

Improved Postoperative Facial Nerve and Hearing Function in Retrosigmoid Vestibular Schwannoma Surgery Significantly Associated with Semisitting Position

OBJECTIVE

The pros and cons of semisitting positioning (SSP) versus lateral, horizontal positioning (LP) during retrosigmoid vestibular schwannoma (VS) surgery, especially concerning postoperative cranial nerve and brain stem preservation, are under continuous discussion.

METHODS

In a single-center retrospective cohort study, 30 VSs operated on in SSP compared with 30 operated on in LP with comparable demography were analyzed. During SSP surgery, transesophageal echocardiographic monitoring for venous air embolism was used continuously. Electrophysiologic cranial nerve monitoring was used in both groups.

RESULTS

Length of surgery was significantly different between both groups: 183 minutes mean in SSP surgery versus 365 minutes mean in LP surgery (P = 0.0001). Postoperative rates of facial palsy and hearing loss were also significantly different. Six months postoperatively, 63% had normal facial nerve function after SSP surgery, whereas in LP surgery, 40% had no facial palsy (P = 0.02). Hearing preservation rate was also significantly different: 44% in SSP surgery compared with 14% in LP surgery who had preserved hearing (P = 0.006). Because of cerebrospinal fluid leaks, there were 3 operative revisions in the LP group (10%) and 1 (3.3%) in the SSP group. A clinically insignificant venous air embolism rate was found in 3.3% of patients (1/30) during SSP surgery. The neurologic outcome after 6 months was 1.2 on the Rankin Scale in the LP group and 1.0 in the SSP group, with zero mortality.

CONCLUSIONS

SSP compared with LP surgery was associated with significantly shorter operation time and better facial and cochlear nerve function in VS surgery postoperatively, without differences in complication rates.

Surgical treatment of vestibular schwannoma. Review of 420 cases

INTRODUCTION AND OBJECTIVES

Vestibular schwannoma is the most frequent cerebellopontine angle tumor. The aim of our study is to reflect our experience in the surgical treatment of this tumor

MATERIAL AND METHODS

Retrospective study of 420 vestibular schwannomas operated in our hospital between 1994-2014. We include tumor size, preoperative hearing, surgical approaches, definitive facial and hearing functional results, and complications due to surgery.

RESULTS

A total of 417 patients with 420 tumors were analyzed, 209 female (50.1%) and 208 male (49.9%). Mean age at diagnosis was 49.8±13.2 years. The majority of the tumors were resected through a translabyrinthine approach (80.2%). Total tumor removal was achieved in 411 tumors (98.3%), and anatomic preservation of facial nerve in 404 (96.2%). Definitive facial nerve outcome was House-Brackmann grade I and II in 69.9%, and was significantly better in tumors under 20mm. Surgical complications included cerebrospinal fluid leakage in 3 patients (0.7%) and retroauricular subcutaneous collection in 16 (3.8%), 5 cases of meningitis (1.2%), 4 patients with intracraneal bleeding (0.9%), and death in 3 patients (0.7%).

CONCLUSIONS

Surgery is the treatment of choice for vestibular schwannoma in the majority of patients. In our experience, the complication rate is very low and tumor size is the main factor influencing postoperative facial nerve function.

Surgical treatment of acoustic neuroma: Outcomes and indications

AIM

Surgery for acoustic neuroma has developed over the years with a gradual improvement in outcome. The goal of surgery should be cure of the disease and a low morbidity, preserving facial nerve function - and hearing, too, whenever feasible (i.e. in small tumors). The most appropriate approach must be decided case by case.

BACKGROUND

Results of microsurgery remain heterogeneous, however, probably due to the different amount of experience gained at different centers.

MATERIALS AND METHODS

Surgical series reported in the recent literature (2012-2015) were critically reviewed, along with some older papers with particularly representative series.

RESULTS AND CONCLUSION

Considering patients' age, surgical morbidity of different approaches, tumor size and hearing, some principles can be identified on which to base surgical indications with a view to achieving the goals of curing the disease with a low morbidity, preserving facial nerve function and hearing, too, whenever feasible (i.e. in patients with small tumors). Different therapeutic approaches are discussed.

Internal Auditory Canal Decompression for Hearing Maintenance in Neurofibromatosis Type 2 Patients

BACKGROUND:

In neurofibromatosis type 2 (NF2), multiple therapeutic options are available to prevent bilateral hearing loss that significantly affects the quality of life of patients.

OBJECTIVE:

To evaluate the morbidity and functional results of internal auditory canal (IAC) decompression in NF2 patients with an only hearing ear.

METHODS:

Twenty-one NF2 patients operated on for IAC decompression in a 3-year period with a minimum follow-up of 1 year were included in this retrospective study. They presented unilateral deafness due to previous contralateral vestibular schwannoma removal in 16 patients or contralateral hearing loss due to the tumor in 5 patients. Hearing level was of class A (American Academy of Otolaryngology-Head and Neck Surgery classification) in 7 patients, B in 8 patients, C in 1 patient, and D in 5 patients. Pure-tone average and speech discrimination score evaluations were performed at 6 days, 1 year, and during the follow-up. Eight patients had postoperative chemotherapy.

RESULTS:

No case of facial nerve palsy was observed. In the early postoperative period; all patients maintained the hearing class of the preoperative period. At 1-year follow-up, all but 3 patients maintained their hearing scores; at last follow-up (mean follow-up, 23 + 8 months; range, 12-44 months), hearing classes remained stable with only 1 patient worsening from class B to C and 1 patient improving from class D to B.

CONCLUSION:

Decompression of IAC seems to be a useful procedure for hearing maintenance in NF2 patients, with very low morbidity. Ideal timing and association with chemotherapy should be evaluated in the future.

Does attempt at hearing preservation microsurgery of vestibular schwannoma affect postoperative tinnitus?

Background. The aim of this study was to analyze the effect of vestibular schwannoma microsurgery via the retrosigmoid-transmeatal approach with special reference to the postoperative tinnitus outcome. Material and Methods. A prospective study was performed in 89 consecutive patients with unilateral vestibular schwannoma indicated for microsurgery. Patient and tumor related parameters, pre- and postoperative hearing level, intraoperative findings, and hearing and tinnitus handicap inventory scores were analyzed. Results. Cochlear nerve integrity was achieved in 44% corresponding to preservation of preoperatively serviceable hearing in 47% and useful hearing in 21%. Main prognostic factors of hearing preservation were grade/size of tumor, preoperative hearing level, intraoperative neuromonitoring, tumor consistency, and adhesion to neurovascular structures. Microsurgery led to elimination of tinnitus in 66% but also new-onset of the symptom in 14% of cases. Preservation of useful hearing and neurectomy of the eighth cranial nerve were main prognostic factors of tinnitus elimination. Preservation of cochlear nerve but loss of preoperative hearing emerged as the main factor for tinnitus persistence and new onset tinnitus. Decrease of THI scores was observed postoperatively. Conclusions. Our results underscore the importance of proper pre- and intraoperative decision making about attempt at hearing preservation versus potential for tinnitus elimination/risk of new onset of tinnitus.

Topographic Changes in Petrous Bone Anatomy in the Presence of a Vestibular Schwannoma and Implications for the Retrosigmoid Transmeatal Approach

BACKGROUND:

The maneuver of transmeatal drilling carries the risk of injuring inner ear structures, which may cause immediate or delayed hearing loss.

OBJECTIVE:

To describe the changes in petrous bone anatomy caused by the tumor and to analyze both the incidence and the risk pattern for violation of the endolymphatic system in a surgical series.

METHODS:

One hundred patients operated on for vestibular schwannoma were included in this prospective study. Thin-slice computed tomography was performed before and after surgery. We assessed topographic measurements on both the pathological and healthy sides. Postoperatively, we evaluated anatomic and functional values.

RESULTS:

The diameter of the internal auditory canal was significantly larger (P &lt; .001) in the petrous bones of the affected sides than in the contralateral healthy sides. An average of 5.6 ± 1.8 mm of the internal auditory canal was drilled, and the distance from the medial border of the sigmoid sinus to the drilling line (tangential to the drilled surface of the posterior lip of the internal auditory canal) was 9.8 ± 2.9 mm. A postoperative violation of the vestibular aqueduct (VA) was detected in 41 cases; the VA was intact in 55 cases; and the VA could not be clearly defined in 4 cases. The incidence of VA injury increased with increasing tumor size. In the patient group with good preoperative and postoperative hearing function, a VA injury occurred in 26% of cases, whereas the incidence increased to 67% in preoperatively deaf patients.

CONCLUSION:

Vestibular schwannomas cause significant distortion of the petrous bone anatomy. Detailed preoperative knowledge of the topography is necessary for the preservation of function.

Diffusion tensor imaging–based fiber tracking for prediction of the position of the facial nerve in relation to large vestibular schwannomas

Object

The reliable preoperative visualization of facial nerve location in relation to vestibular schwannoma (VS) would allow surgeons to plan tumor removal accordingly and may increase the safety of surgery. In this prospective study, the authors attempted to validate the reliability of facial nerve diffusion tensor (DT) imaging–based fiber tracking in a series of patients with large VSs. Furthermore, the authors evaluated the potential of this visualization technique to predict the morphological shape of the facial nerve (tumor compression–related flattening of the nerve).

Methods

Diffusion tensor imaging and anatomical images (constructive interference in steady state) were acquired in a series of 22 consecutive patients with large VSs and postprocessed with navigational software to obtain facial nerve fiber tracking. The location of the cerebellopontine angle (CPA) part of the nerve in relation to the tumor was recorded during surgery by the surgeon, who was blinded to the results of the fiber tracking. A correlative analysis was performed of the imaging-based location of the nerve compared with its in situ position in relation to the VS.

Results

Fibers corresponding to the anatomical location and course of the facial nerve from the brainstem to the internal auditory meatus were identified with the DT imaging–based fiber tracking technique in all 22 cases. The location of the CPA segment of the facial nerve in relation to the VS determined during surgery corresponded to the location of the fibers, predicted by the DT imaging–based fiber tracking, in 20 (90.9%) of the 22 patients. No DT imaging–based fiber tracking correlates were found with the 2 morphological types of the nerve (compact or flat).

Conclusions

The current study of patients with large VSs has shown that the position of the facial nerve in relation to the tumor can be predicted reliably (in 91%) using DT imaging–based fiber tracking. These are preliminary results that need further verification in a larger series.

Hearing Preservation Using the Middle Fossa Approach for the Treatment of Vestibular Schwannoma

BACKGROUND:

The incidence of small vestibular schwannomas in patients with serviceable hearing is increasing because of the widespread use of MRI. The middle fossa approach provides the patient with an opportunity for tumor removal with hearing preservation.

OBJECTIVE:

To determine the rate of hearing preservation and facial nerve outcomes after removal of a vestibular schwannoma with the use of the middle fossa approach.

METHODS:

A retrospective case review at a tertiary, academic medical center was performed identifying patients from 1998 through 2008 that underwent removal of a vestibular schwannoma by the middle fossa approach. Preoperative and postoperative audiograms were compared to determine hearing preservation rates. In addition, facial nerve outcomes at last follow-up were recorded.

RESULTS:

Forty-six patients underwent a middle fossa craniotomy for the removal of a vestibular schwannoma. Of the 38 patients that had class A or class B hearing preoperatively, 24 (63.2%) retained class A or B hearing and 29 (76.3%) retained class A, B, or C hearing. When tumors were 10 mm or less in patients with class A or B preoperative hearing, 22 of 30 patients (73.3%) retained class A or B hearing. When the tumor size was greater than 10 mm in patients with class A or B preoperative hearing, 2 of 8 patients (25%) retained class A or B hearing. At most recent follow-up, 76.1% of patients had House-Brackmann grade I facial function, 13.0% had House-Brackmann grade II facial function, and 10.9% had House-Brackmann grade III facial function.

CONCLUSION:

Hearing preservation rates are excellent using the middle fossa approach, especially for smaller tumors. No patient experienced long-term facial nerve function worse than House-Brackmann grade III.

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.

Exercise with visual feedback improves postural stability after vestibular schwannoma surgery

We analyzed the effect of 2-week individualized visual feedback-based balance training on the postural control of patients undergoing retrosigmoid microsurgical removal of vestibular schwannoma. We performed prospective evaluation of 17 patients allocated into two groups: feedback group (9 patients, mean age 37 years) and standard physiotherapy group (8 patients, mean age 44 years). Patients in both the groups were treated once per day by intensive rehabilitation from 5th to 14th postoperative day. Rehabilitation of patients in the feedback group was performed using the visual feedback and force platform. Results were evaluated on the beginning and at the end of rehabilitation program (e.g. 5th and 14th postoperative day). Outcome measures included posturography during quiet stance under four different conditions by the modified Clinical Test for Sensory Interaction of Balance. Body sway was evaluated from center of foot pressure. Compensation of Center of pressure (CoP) parameters in stance on firm surface was similar in the control and feedback groups. However, in stance on foam surface with eyes closed the patients from the feedback group were better compensated and CoP parameters differed significantly (p < 0.05). This prospective clinical study suggests that specific exercises with visual feedback improve vestibulospinal compensation in patients after vestibular schwannoma surgery and thus can improve their quality of life.