Hearing Preservation Research Articles

Long-Term Hearing Outcome For Vestibular Schwannomas After Microsurgery And Radiotherapy: A Systematic Review and Meta-Analysis.

Hearing loss is a common symptom associated with vestibular schwannoma (VS), either because of the tumor's effects on the cochlear nerve or due to active treatments such as surgery or stereotactic radiosurgery (SRS). Treatment decisions for VS are based on factors including tumor size, hearing status, patient symptoms, and institutional preference. The study aimed to investigate long-term auditory outcomes in VS patients undergoing active treatments with a hearing preservation intent. A systematic literature review was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, searching Scopus, Pubmed, and Web of Science databases from inception to January 2024. Studies meeting inclusion criteria, including a minimum 5-year follow-up and assessment of pre- and posttreatment hearing outcomes, were included. Pooled prevalence estimates for serviceable hearing after SRS and microsurgery were calculated using MetaXL software. Risk of bias assessment was performed with the Risk of Bias in Non-randomized Studies of Interventions tool. Nine studies met the inclusion criteria, with 356 patients included for analysis. The pooled prevalence of maintaining serviceable hearing after SRS at 10 years was 18.1% (95% confidence interval [CI]: 1.7%-43.3%), with wide prediction intervals indicating variability in outcomes. Microsurgery demonstrated a higher prevalence of maintaining long-term serviceable hearing, with a pooled estimate of 74.5% (95% CI: 63.5%-84.1%). This systematic review underscores the importance of long-term follow-up in evaluating auditory outcomes in VS treatment. Despite the biases inherent to pretreatment patients selection, hearing preservation microsurgery for sporadic VS removal demonstrated favorable and stable long-term serviceable hearing.

Our Experience with Labyrinthine Fistula: Prospective Hearing Outcomes.

Chronic otitis media with cholesteatoma is a locally destructive middle ear infection with bone erosive properties which can lead to fistula if erodes labyrinth. A prospective observational study was conducted at tertiary health care centre with a total of 12 patients who presented with complaints of otorrhoea, hearing loss and vertigo. Such patients were evaluated clinic audiologically and radiologically as a pre op assessment. Post-surgery audiological assessment was done. Hearing preservation was seen in 91.7% patients and none of the patients had iatrogenic sensorineural hearing loss. Complete removal of the cholesteatoma is beneficial and does not lead to any iatrogenic SNHL when performed meticulously. A newer way of diagnosing membranous labyrinthine breach utilizing Magnetic Resonance Imaging T2 Diffusion Weighted (MRI- T2 DW) sequence can be implemented.

Intraoperative Hearing Monitoring Using ABR and TT-ECochG and Hearing Preservation during Vestibular Schwannoma Resection.

Background: Quick and appropriate diagnostics and the use of intraoperative monitoring (IM) of hearing during vestibular schwannoma (VS) resection increase the likelihood of hearing preservation. During surgery, various methods of IM can be used, i.e., auditory brainstem responses (ABRs), transtympanic electrocochleography (TT-ECochG), and direct cochlear nerve action potentials. The aim of the study was to evaluate the prognostic values of IM of hearing using ABR and TT-ECochG in predicting postoperative hearing preservation and to evaluate relationships between them during various stages of surgery. Methods: This retrospective study presents the pre- and postoperative audiological test results and IM of hearing records (TT-ECochG and ABR) in 75 (43 women, 32 men, aged 18-69) patients with diagnosed VS. Results: The preoperative pure tone average hearing threshold was 25.02 dB HL, while after VS resection, it worsened on average by 30.03 dB HL. According to the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) Hearing Classification, before and after (pre/post) surgery, there were 47/24 patients in hearing class A, 9/8 in B, 2/1 in C, and 17/42 in D. In speech audiometry, the average preoperative speech discrimination score at an intensity of 60 dB SPL was 70.93%, and after VS resection, it worsened to 38.93%. The analysis of electrophysiological tests showed that before the tumor removal the I-V ABR interlatencies was 5.06 ms, and after VS resection, it was 6.43 ms. Conclusions: The study revealed correlations between worse postoperative hearing and changes in intraoperatively measured ABR and TT-ECochG. IM of hearing is very useful in predicting postoperative hearing in VS patients and increases the chance of postoperative hearing preservation in these patients.

Intra-Cochlear Electrode Position Impacts the Preservation of Residual Hearing in an Animal Model of Cochlear Implant Surgery.

Preservation of residual hearing after cochlear implantation remains challenging. There are several approaches to preserve residual hearing, but the configuration of the implant electrode array seems to play a major role. Lateral wall electrode arrays are seemingly more favorable in this context. To date, there are no experimental data available which correlate the spatial electrode position in the scala tympani with the extent of hearing preservation. Based on micro-computed tomography (µCT) imaging data, this study analyses the exact position of a pure silicone electrode array inserted into the cochlea of four guinea pigs. Array position data were correlated with the extent of hearing loss after implantation, measured using auditory brainstem measurements in the frequency range of the area occupied by the electrode array area as well as apical to the array. The use of pure silicone arrays without electrodes resulted in artifact-free, high-resolution µCT images that allowed precise determination of the arrays' positions within the scala tympani. The electrode arrays' locations ranged from peri-modiolar to an anti-modiolar. These revealed a correlation of a lower postoperative hearing loss with a higher spatial proximity to the lateral wall. This correlation was found in the low-frequency range only. A significant correlation between the inter-individual differences in the diameter of the scala tympani and the postoperative hearing loss could not be observed. This study demonstrates the importance of the intra-cochlear electrode array's position for the preservation of residual hearing. The advantage of such an electrode array's position approximated to the lateral wall suggests, at least for this type of electrode array applied in the guinea pig, it would be advantageous in the preservation of residual hearing for the apical part of the cochlea, beyond the area occupied by the electrode array.

Factors Affecting Speech Discrimination After Vestibular Schwannoma Resection.

Investigate the relationship between word recognition score (WRS) and pure tone average (PTA) after hearing preservation surgery for vestibular schwannomas (VS) as well as evaluate the consistency of hearing classification systems. A retrospective chart review was performed. This study included patients from a single academic tertiary referral hospital. Patients with VS and serviceable hearing who underwent hearing preservation surgery 2014-2023. Patients excluded for neurofibromatosis 2 and lacking pre/postop audiograms. All patients underwent resection of vestibular schwannoma. Pre/postop WRS, PTA, and AAO-HNS, Gardner-Robertson (GR), and WRS Class (WRSC) hearing classifications. Seventy-five patients were included. Average preop and postop PTA and WRS were 26 ± 12 dB, 79 ± 39 dB, 92 ± 12%, and 33 ± 43%, respectively. Postop PTAs were distributed along the complete testable decibel range, while the postop WRS displayed a bimodal distribution, with WRS >50% or <20%. Worsening intraop ABR changes were significantly associated with poorer hearing outcomes ( p = 0.005). With increasing Koos grades, intraop ABRs were significantly more likely to exhibit changes ( p = 0.005). AAO-HNS and GR classified patients nearly identically, while the WRSC resulted in more class I and fewer class II. The cutoff of serviceable hearing was comparable across all classification systems. Effects on the brainstem component of Koos 3-4 tumors may particularly disturb speech processing. This effect seems amplified by surgical dissection. AAO-HNS, GR, and WRSC hearing classifications are comparable in describing serviceable hearing in vestibular schwannoma patients.

Long-term hearing prognosis after vestibular schwannoma surgery with retrolabyrinthine approach.

The retrolabyrinthine approach is a surgical method designed to preserve hearing after surgery. When paired with intraoperative monitoring and an endoscope, this approach has demonstrated high rates of postoperative hearing preservation. However, the long-term prognosis of hearing preservation after utilizing this approach for vestibular schwannomas remains unexplored. This study aimed to examine the long-term outcomes of preserved hearing, providing insights into the suitability of the retrolabyrinthine approach for hearing preservation surgery. This study included 34 patients with preserved hearing after vestibular schwannoma surgery using the retrolabyrinthine approach at a single center. Long-term hearing prognosis and requirement for additional interventions were retrospectively examined. Immediate after post-operative hearing preservation rate was 71.7%. Among the 34 patients with preserved hearing post-vestibular schwannoma surgery, four (11.8%) required additional interventions. Other patients experienced a gradual deterioration in their hearing status, with an approximate 10 dB decline during the 5-year follow-up; however, a serviceable hearing level persisted long after the surgery in these individuals. This study indicated the rationale for the retrolabyrinthine approach as a hearing preservation surgery for vestibular schwannomas, emphasizing its long-term hearing prognosis.

Diving technique of cochlear implant electrode insertion for hearing preservation: how I do it.

Preservation of intracochlear structures and residual hearing has become a major concern in modern cochlear implant. Consequently, many efforts have been made to minimize intraoperative trauma, especially while cochlear fenestration and electrode insertion. Building on the core concept of "soft surgery", a modified approach, described as diving technique for cochlear implant electrode array insertion is proposed. Steps and technical points are presented with figures, video and review of relevant anatomy. This novel diving technique is operationally feasible and safe, promising to minimize intraoperative invasion and thus preserve residual hearing in cochlear implant.

Hearing Function after CyberKnife for Vestibular Schwannoma: A Systematic Review.

Introduction CyberKnife (CK) radiosurgery is a treatment strategy for vestibular schwannoma (VS). Objectives To evaluate hearing preservation (HP) after CK for VS. Data Synthesis The study was conducted following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement, and it was registered at the International Prospective Register of Systematic Reviews (PROSPERO, under number CRD42021250300). The inclusion criteria were based on the population, intervention, comparison, outcome, timing and study design (PICOTS) strategy: population - patients with VS; intervention - CK; Comparison - none; Outcome - serviceable HP defined by Gardner and Robertson as grades I or II, or by the American Academy of Otolaryngology and Head and Neck Surgery as classes A or B; timing - mean follow-up longer than 1 year; and study design - retrospective or prospective studies. The exclusion criteria were: studies not published in English; studies published before January 2000 and after October 2021; and studies only including patients with neurofibromatosis type 2 or submitted to a previous treatment. The PubMed/MEDLINE, EMBASE, Web of Science, Cochrane Library, LILACS, and IBECS databases were used and last searched on October 27th, 2021. Statistical heterogeneity was assessed using I 2 statistics. The appraisal checklist was used to assess the risk of bias in the included studies. A total of 222 studies were analyzed, and 13 were included in the synthesis, which represents 493 participants with serviceable hearing before intervention. The mean HP rate after CK using a random effects model was of 68% (95% confidence interval [95%CI]: 59-76%) at a mean follow-up of 42.96 months. Conclusion The longer follow-up period was associated with a lower HP rate after CK radiosurgery for VS in the qualitative synthesis.

Knowledge, Attitude and Practices (KAP) regarding hearing health and noise-induced hearing loss among folk/light music professionals from Chennai

Introduction: Musicians are exposed to music at high intensities and are at risk for developing noise- induced hearing loss (NIHL). Since hearing is so important to their career, they deserve special consideration. To avoid the deleterious effects of loud music, the professionals should be sensitized to the noise exposure and the use of strategies to prevent NIHL. The aim of the study is to determine the knowledge and attitude towards noise induced hearing disorders, and hearing conservative practices among professional musicians. Method: A KAP questionnaire was administered online to 136 professional musicians belonging to folk/ light music genre in Chennai. The participants were 115 males and 21 females, ranging in age from 18 to 75 years with the mean age of 29 (SD= 11). Results: The findings revealed that musicians were aware of the nature and cause of NIHL, but knowledge of NIHL prevention and treatment was limited to few. They had common misconceptions about the sources of harmful loud sounds, the effects of hearing loss, and hearing conservation strategies. Only a few participants reported to have used Ear Protective Devices (EPDs). Conclusion: Although musicians are aware of the risks of exposure to loud noise, they seldom use hearing protection. It is therefore vital to provide crucial information regarding NIHL and its prevention and promote musicians for better hearing preservation practices.

Advances in Evaluation of Electrode Insertion Trauma Induced Residual Hearing loss in Cochlear Implant Recipients and its significance- A Narrative Review.

Cochlear implant surgery has revolutionized the management of profound hearing loss, with a growing focus on preserving residual hearing, particularly low-frequency hearing. This review synthesizes existing literature on cochlear implantation techniques, surgical principles, and emerging therapies aimed at reducing post-implantation hearing loss. Methodologically, a comprehensive narrative literature review was conducted, encompassing various study designs and participant demographics. The search strategy involved major biomedical databases, focusing on articles in English. Surgical techniques such as "soft surgery" emphasize minimizing mechanical stress on the cochlea, while advancements in pharmacological agents explore the use of corticosteroids, neurotrophins, and growth factors to enhance hearing preservation. Electrode design and insertion strategies are evolving to minimize trauma and optimize hearing outcomes, including consideration of insertion forces and electrode array designs. Evaluating residual hearing loss involves sophisticated techniques like electrocochleography and radiological imaging. The impact of residual hearing on auditory verbal outcomes is variable, with studies indicating positive correlations with language development, particularly in speech production. Emerging strategies in electrode design, surgical techniques, and drug delivery hold promise for improving outcomes in cochlear implantation. However, challenges such as the lack of standardized guidelines and the need for further clinical trials remain. Future directions include the exploration of nanotechnologies, gene therapies, and stem cells for constructing bionic ears, although ethical and technical hurdles persist. This review underscores the ongoing efforts to enhance cochlear implant functionality and the need for continued research to optimize outcomes for patients with hearing loss.

Sialyllactose preserves residual hearing after cochlear implantation

In individuals with hearing loss, protection of residual hearing is essential following cochlear implantation to facilitate acoustic and electric hearing. Hearing preservation requires slow insertion, atraumatic electrode and delivery of the optimal quantity of a pharmacological agent. Several studies have reported variable hearing outcomes with osmotic pump-mediated steroid delivery. New drugs, such as sialyllactose (SL) which have anti-inflammatory effect in many body parts, can prevent tissue overgrowth. In the present study, the positive effects of the pharmacological agent SL against insults were evaluated in vitro using HEI-OC1 cells. An animal model to simulate the damage due to electrode insertion during cochlear implantation was used. SL was delivered using osmotic pumps to prevent loss of the residual hearing in this animal model. Hearing deterioration, tissue fibrosis and ossification were confirmed in this animal model. Increased gene expressions of inflammatory cytokines were identified in the cochleae following dummy electrode insertion. Following the administration of SL, insertion led to a decrease in hearing threshold shifts, tissue reactions, and inflammatory markers. These results emphasize the possible role of SL in hearing preservation and improve our understanding of the mechanism underlying hearing loss after cochlear implantation.

Management of Petrous Bone Cholesteatoma: The Gruppo Otologico Experience.

The term petrous bone cholesteatoma (PBC) refers to lesions extending deep to the bony labyrinth via superior, inferior, and posterior cell tracts. PBC is a rare incidence accounting for only 4-9% of petrous bone lesions. Lesions of petrous bone represent a real surgical challenge due to its complex relationship with critical neurovascular structures. To demonstrate our 40-plus years' experience in the management of PBC, depict the clinical features of PBC according to Sanna's Classification, evaluate the postoperative follow-up of surgically treated PBC patients, and determine the recurrence rate. Retrospective medical record review. Medical records of 298 PBC cases operated from the year 1983 to 2024 were thoroughly evaluated. A total of 298 PBC cases were surgically treated at our center. The average age at presentation in this series was 47 years. Males are more affected than females with a male-to-female ratio of 2.2:1. The most common presenting symptoms were hearing loss (84%), tinnitus (48%), and facial nerve paralysis (45%). Mixed hearing loss (41%) was the commonest audiometric pattern of hearing loss followed by conductive hearing loss (26%) and profound sensorineural hearing loss (4%) and a total of 86 (29%) had anacusis at presentation. On preoperative facial nerve function examination, 133(45%) of patients had various degrees of paresis and complete paralysis whereas 55% had normal HB-I function. The commonest degree of paresis noted was HB-III (18%) followed by HB-VI (5%). A total of 150 (50%) patients had previous otologic surgery and two-thirds of these cases had two or more prior otologic surgeries. According to Sanna's PBC Classification system, we identified that the supralabyrinthine class (44%) is the commonest of all classes followed by massive (33%), infralabyrinthine-apical (9%), infralabyrinthine(8%), and apical (5%) classes in that order. However, only ten patients had congenital type of PBC. Extension to clivus, sphenoid, nasopharynx, intradural space, and occipital condyle was found in 8, 2, 1, and 2 cases respectively. The most commonly used surgical approaches at our center were TO, MTCA with rerouting of the facial nerve, and TLAB with external auditory canal (EAC) closure. Postoperative complications were minimal and the duration of follow-up ranged from one to 458 months with a mean duration of 65 months. Residual lesions were evident in 11 cases (3.7%), with the surgical cavity, middle and posterior fossa dura, and jugular bulb being the commonest sites. Petrous bone cholesteatoma represents diagnostically and surgically challenging lesions of temporal bone which are usually frustrating to the treating surgeon. A high index of clinical suspicion, thorough clinical evaluation examination, and preoperative radiologic evaluation make the diagnosis easier. Preoperative anatomic classification of the lesion enables the physician to choose the appropriate surgical approach. Sanna's classification is widely used to classify PBC in relation to the labyrinthine block. Radical disease removal should always come before hearing preservation. Cavity obliteration is the solution to the problems related to a large cavity. Finally, advancements in lateral skull base approaches create adequate surgical access for the complete removal of the lesion with excellent control of critical neurovascular structures.

The Role of Trublue Laser in Cholesteatoma Surgery.

The retrospective cohort study aimed to determine the safety and efficacy of TruBlue laser application in cholesteatoma surgeries. All cholesteatoma surgeries conducted from January 2018 to January 2022 in two tertiary referral hospitals in Hong Kong, with and without use of TruBlue laser, were included. Pure tone audiogram was done pre- and post-operatively to assess hearing. Disease extent was graded with ChOLE score and ChOLE staging. Residual disease was determined clinically, radiologically, or surgically with second look operation. One hundred twenty cholesteatoma cases were identified. There are 39.2% (n = 47) of the cholesteatoma surgeries that utilized TruBlue laser, while 60.8% (n = 73) did not. Overall follow-up duration was 21 ± 12.4 months, ranging from 2 to 47 months. Both groups were similar in demographics, pre-operative hearing and ChOLE staging. The length of stay was comparable in both groups (2 ± 2 days in nonlaser, 1 ± 1 day in laser, p = 0.31). There was no facial nerve injury related to surgery in both groups, and overall complication rates were similar (4.1% in nonlaser, 4.3% in laser, p = 0.97). The postoperative hearing was comparable with good hearing preservation in both groups. Residual cholesteatoma occurred in 17.8% (n = 13) in nonlaser group, and 21.3% (n = 10) in laser group, which was not statistically significant (p = 0.64). Seventy percent of the cholesteatoma residual in laser group occurred at area that TruBlue LASER cannot be applied. TruBlue LASER was safe in cholesteatoma surgeries, though no added benefits were shown in reducing cholesteatoma residual rate. A larger controlled study is warranted to discern the true effect of TruBlue LASER. Level 3.

Development of a Semi-Automated Approach for the Quantification of Neuronal Cells in the Spiral Ganglion of the Whole Implanted Gerbil Cochlea, Acquired by Light-Sheet Microscopy.

Assessing cochlear implantation's impact on cell loss and preventing post-implant cochlear damage are key areas of focus for hearing preservation research. The preservation of auditory neuronal and sensory neural hearing cells has a positive impact on auditory perception after implantation. This study aimed to provide details on a semi-automated spiral ganglion neuronal cell counting method, developed using whole implanted gerbil cochlea acquisitions with light-sheet microscopy. Mongolian gerbils underwent right cochlear implantation with an electrode array whose silicone was loaded with dexamethasone or not and were euthanized 10 weeks after implantation. The cochleae were prepared according to a 29-day protocol, with the electrode array in place. Light-sheet microscopy was used for acquisition, and Imaris software was employed for three-dimensional analysis of the cochleas and semi-automatic quantification of spiral ganglion cells. The imaJ software was used for the manual quantification of these cells. Six cochleae were acquired by light-sheet microscopy, allowing good identification of cells. There was no significant difference between the mean number of spiral ganglion cells obtained by manual and semi-automatic counting (p = 0.25). Light-sheet microscopy provided complete visualization of the spiral ganglion and cell identification. The semi-automated counting method developed using Imaris software tools proved reliable and efficient and could be applied to a larger sample to assess post-cochlear implant cell damage and the efficacy of protective drugs delivered to the inner ear.

P.096 Hearing preservation and quality of life outcomes in partial labyrinthectomy petrous apicectomy for microsurgical resection of large posterior fossa skullbase tumors

Background: The Partial Labyrinthectomy Petrous Apicectomy (PLPA) aims to give transpetrosal access whilst preserving hearing for challenging tumors such as petroclival meningioma. There are few studies assessing resection and morbidity and no large studies that document hearing preservation and quality of life (QOL). We present the first large series to do so. Methods: A retrospective review was performed of all PLPA cases between 2005 and 2023 at a tertiary center. Demographics, tumor characteristics, neuromonitoring, hearing and surgical outcomes were collected. QOL was measured with the 36-item short form survey (SF-36). Results: Of 73 PLPAs, data for 56 patients undergoing 57 surgeries was obtained. Petroclival meningioma (57.8%) and epidermoid tumors (21.0%) were common indications . The mean patient age and tumor size were 51.6 years and 44mm. Gross total resection was achieved in 40.3%, near total in 15.8% and subtotal in 43.8% of cases with no perioperative mortality and was not influenced by attempted hearing preservation (p=0.183). Of 39 hearing preservation cases, 27 (69.2%) were preserved, 10 (25.6%) were lost and 2 had unclear outcomes. Conclusions: Improved microsurgery and neuromonitoring during PLPA leads to decreased mortality and morbidity compared to historical cohorts while achieving a high rate of resection, hearing preservation and maintained QOL.

Quality of Life for Patients with Sporadic Small Vestibular Schwannomas Following Middle Fossa Craniotomy.

To evaluate quality-of-life outcomes for patients with vestibular schwannomas (VS) undergoing a middle cranial fossa (MCF) approach. Prospective study from 2018 to 2023. Tertiary academic institution. Adults with sporadic VS. MCF. The primary outcome measure was the change in preoperative and 1-year postoperative Penn Acoustic Neuroma Quality-of-life (PANQOL) scores. Secondary outcome measures included hearing preservation and facial nerve function. Of the 164 patients who underwent MCF for sporadic VS, 78 patients elected to voluntarily complete preoperative PANQOL assessments prior to surgery. Seventy-one (91%) of those 78 patients completed postoperative PANQOL surveys. Fifty (70%) of the respondents were female and the median age was 48 years (range, 27-71 years). Overall, at 1-year postsurgery, a minimal clinically important difference (MCID) was obtained in the hearing (mean difference, 10.5; 95% confidence interval [CI], 4.3-16.7) and anxiety (mean difference, 18.8; 95% CI, 11.7-25.9) domains. For patients with hearing preservation (n = 48, 68%), MCIDs were reached in the hearing (mean difference, 13.4; 95% CI, 6.3-20.6), anxiety (mean difference, 20.8; 95% CI, 11.8-29.9), energy (mean difference, 13.7; 95% CI, 3.6-23.8), pain (mean difference, 13.7; 95% CI, 3.6-23.8) domains, and overall PANQOL scores (mean difference, 12.7; 95% CI, 7.1-18.3). Postoperatively, 64 (90%) patients maintained a House-Brackmann I. To our knowledge, this is the largest study examining disease-specific QOL for VS patients undergoing MCF. Based on our institution's experience, MCF approach for small VS is associated with clinically meaningful improvements in QOL, hearing preservation, and excellent facial nerve outcomes.

A Randomised Controlled Trial Comparing Intratympanic Gentamicin with Methylprednisolone in Meniere's Disease with Good Hearing.

Randomised prospective parallel group trial. Tertiary care centre in South India. Forty patients with unilateral Meniere's disease and serviceable hearing with vertigo following 6months of conservative therapy were enrolled between November 2018 and March 2020. Twenty patients were administered with one dose of intratympanic Gentamicin (40mg/ml) and the other half were given intratympanic Methylprednisolone (40mg/ml, 4 injections given on alternate days). Pure tone audiogram, speech discrimination score, number of vertigo episodes, dizziness handicap inventory, tinnitus handicap inventory and functional scores were compared before treatment, 3months later and up to 24months. There was no significant difference between the two treatments with regard to short term as well as long term DHI scores, THI scores, Functional level score and average pure tone audiogram of patients. In patients with unilateral Meniere's disease who have good hearing, one dose of Gentamicin had equivalent effect to that of four doses of Methylprednisolone in vertigo and tinnitus control, hearing preservation and quality of life.

Novel standardized indexes of brainstem auditory evoked potentials for predicting hearing preservation in vestibular schwannomas

Hearing preservation (HP) during vestibular schwannomas (VSs) surgery poses a significant challenge. Although brainstem auditory evoked potentials (BAEPs) on the affected side are commonly employed to monitor cochlear nerve function, their low signal-to-noise ratio (SNR) renders them susceptible to interferences, compromising their reliability. We retrospectively analyzed the data of patients who underwent tumor resection, while binaural brainstem auditory evoked potentials (BAEPs) were simultaneously recorded during surgery. To standardize BAEPs on the affected side, we incorporated the synchronous healthy side as a reference (interval between affected and healthy side ≤ 3 min). A total of 127 patients were enrolled. Comparison of the raw BAEPs data pre- and post-tumor resection revealed that neither V-wave amplitude (Am-V) nor latency (La-V) could serve as reliable predictors of HP simultaneously. However, following standardization, V-wave latency (STIAS-La-V) and amplitude (STIAS-Am-V) emerged as stable predictors of HP. Furthermore, the intraoperative difference in V-wave amplitude (D-Am-V) predicted postoperative HP in patients with preoperative HP and remained predictive after standardization. The utilization of intraoperative synchronous healthy side BAEPs as a reference to eliminate interferences proves to be an effective approach in enhancing the reliability of BAEPs for predicting HP in VSs patients.

Retrolabyrinthine approach to the lateral skull base: The value of preoperative temporal bone CT analysis

PurposeThe most used neurosurgical approach to reach cerebellar-pontine angle is the retrosigmoid route. This article describes the presigmoid approach which requires excellent knowledge of the labyrinthine block together with quantitative analysis of temporal bone CT. MethodsCT-based quantitative measurements were obtained in patients undergoing vestibular neurectomy with a presigmoid approach. Eighteen patients were enrolled, and five measures were taken: Trautmann’s area, the petro-clival angle, presigmoid dura length and its angle. The relationship between these measurements and hospitalization days, operating times, and complications was explored. ResultsThe posterior semicircilar canal (PSC)-sigmoid sinus (SS) distance, presigmoid dura- internal auditory canal (IAC)-PSC angle, and duration of surgery are predictors of complications. Specifically, a PSC-sigmoid sinus distance <11 mm, a dura presig-IAC-PSC angle <14 are associated with the highest risk of complications. ConclusionPreoperative temporal bone CT scan can guide the surgeon through the narrowest areas of the surgical approach. Trautmann’s triangle area and petro-clival angle reduction are challenging and can be faced with combined microscopic-endoscopic technique, and with optics angulation-rotation. The retrolabyrinthine approach can enable hearing preservation and minimal cerebellar retraction.

Surgical Outcome of Vestibular Schwannoma in a Tertiary Care Hospital, Dhaka

Background: Presenting symptoms, treatment considerations, and outcome are strongly related to the extension of vestibular schwannomas (VS). The aim of the current retrospective study was to analyze the clinical features, microsurgical treatment, and outcome of VS with brainstem compression. Methods: 130 patients presented with VS who had undergone operative procedures performed in our unit from Jan, 2017 to may, 2022. The facial nerve function and hearing assessment was done according to House-Brackmann [HB] grading and pure tone audiometry (PTA) respectively. All patients were operated by retro-sigmoid retromastoid sub-occipital approach. Results: Most patients had large tumors and had no useful hearing (75.38%), had disabling cerebellar ataxia (84.61%) and presented with features of raised intracranial pressure (46.15%). Complete tumor excision was carried out 92.30% and anatomical preservation of facial nerve was achieved in 87.50% cases. Hearing preservation was achieved in eight patients. Cerebrospinal fluid leak with or without meningitis and transient lower cranial nerve paresis were common complications. The mortality rate was 7.69% Conclusions: Complete tumor excision with good facial nerve preservation can be achieved in large vestibular schwannomas. Hearing preservation is difficult in larger tumors. Primary microsurgical resection is an appropriate management option for large VS. In our experience, this goal can be achieved safely and successfully by using the retromastoid retrosigmoid sub-occipital approach. Bang. J Neurosurgery 2023; 12(2): 86-93