Preservation Of Hearing Function Research Articles

How I do it: hearing preservation in large vestibular schwannomas using vestibular nerve fiber preservation technique.

To improve hearing function after resection of large vestibular schwannomas, we describe a strategy of vestibular-nerve-fiber preservation. Anatomical considerations and stepwise dissection are described. Steps include locating the vestibular nerve at the brainstem and identifying a dissection plane between nerve fibers and tumor capsule. Using this plane to mobilize and resect tumor reduced manipulation and maintained vascularity of underlying cochlear and facial nerves. Preservation of hearing function is feasible in large vestibular schwannomas with vestibular-nerve-fiber preservation. Reducing manipulation and ischemic injury of underlying cochlear and facial nerves thereby helped facilitate hearing preservation, even in large tumors.

Functional Hearing Preservation in Cochlear Implantation: The Miami Cocktail Effect.

To investigate if pharmacological treatment with prednisone and L-N-acetylcysteine (STE + NAC) influence functional hearing preservation in cochlear implant (CI) surgery. Preimplantation and postimplantation longitudinal case-control study. Tertiary referral center. Pediatric and adult recipients of CI with preimplantation functional hearing defined as an average of air-conducted thresholds at 125, 250, and 500 Hz (low-frequency pure-tone average [LFPTA]) <80 dB. Preimplantation and postimplantation audiometry. Weight-adjusted oral prednisone and L-N-acetylcysteine starting 2 days before surgery (Miami cocktail). Prednisone was continued for 3 days and L-N-acetylcysteine for 12 days after surgery, respectively. Cochlear implantation with conventional length electrodes. Proportion of patients with LFPTA <80 dB, and LFPTA change at 1-year postimplantation. All 61 patients received intratympanic and intravenous dexamethasone intraoperatively, with 41 patients receiving STE + NAC and 20 patients not receiving STE + NAC. At 1-year postimplantation, the proportion of functional hearing preservation was 83% in the STE + NAC group compared with 55% of subjects who did not receive STE + NAC ( p = 0.0302). The median LFPTA change for STE + NAC-treated and not treated subjects was 8.33 dB (mean, 13.82 ± 17.4 dB) and 18.34 dB (mean, 26.5 ± 23.4 dB), respectively ( p = 0.0401, Wilcoxon rank test). Perioperative STE + NAC treatment resulted in 10 dB of LFPTA better hearing than when not receiving this treatment. Better low-frequency preimplantation hearing thresholds were predictive of postimplantation functional hearing. No serious side effects were reported. Perioperative STE + NAC, "The Miami Cocktail," was safe and superior to intraoperative steroids alone in functional hearing preservation 1-year after cochlear implantation.

Hearing preservation in paediatric cochlear implantation with the Nucleus Slim Straight Electrode – our experience

Objective to evaluate the levels of successful hearing preservation and preservation of functional hearing following cochlear implantation (HPCI) in children using the Cochlear Nucleus® Slim Straight Electrode (SSE). Design retrospective case note review of paediatric HPCI cases in our CI centre from 2013 to 2023. Inclusion criteria were attempted hearing preservation surgery, SSE used for implantation, pre-operative hearing thresholds ≤80dBHL at 250 Hz, CI before 18 years of age. Patients were excluded if no postoperative unaided PTA was obtained (poor attendance). Primairy outcome was hearing preservation using the HEARRING group formula; secondary outcome was residual functional hearing (≤80dBHL at 250 Hz/<90dB LFPTA). Study sample 56 patients with 94 CI’s were included for review. Results Hearing preservation was achieved in 94.7% (89/94) of ears and complete preservation in 72% (68/94)). Average functional hearing was preserved in 89% using both criteria for preservation. Long-term follow up data was available for 36 ears (average 35.2 months), demonstrating 88.9% (32/36) complete preservation. Conclusion We have reliably achieved and maintained a high success rate of HPCI using the SSE in our paediatric population. The field of HPCI would benefit from unification of outcome reporting in order to optimise the evidence available to professionals, patients and their carers

Incidence of Cochlear Implant Electrode Contacts in the Functional Acoustic Hearing Region and the Influence on Speech Recognition with Electric-Acoustic Stimulation.

To investigate the incidence of electrode contacts within the functional acoustic hearing region in cochlear implant (CI) recipients and to assess its influence on speech recognition for electric-acoustic stimulation (EAS) users. Retrospective review. Tertiary referral center. One hundred five CI recipients with functional acoustic hearing preservation (≤80 dB HL at 250 Hz). Cochlear implantation with a 24-, 28-, or 31.5-mm lateral wall electrode array. Angular insertion depth (AID) of individual contacts was determined from imaging. Unaided acoustic thresholds and AID were used to calculate the proximity of contacts to the functional acoustic hearing region. The association between proximity values and speech recognition in quiet and noise for EAS users at 6 months postactivation was reviewed. Sixty percent of cases had one or more contacts within the functional acoustic hearing region. Proximity was not significantly associated with speech recognition in quiet. Better performance in noise was observed for cases with close correspondence between the most apical contact and the upper edge of residual hearing, with poorer results for increasing proximity values in either the basal or apical direction ( r14 = 0.48, p = 0.043; r18 = -0.41, p = 0.045, respectively). There was a high incidence of electrode contacts within the functional acoustic hearing region, which is not accounted for with default mapping procedures. The variability in outcomes across EAS users with default maps may be due in part to electric-on-acoustic interference, electric frequency-to-place mismatch, and/or failure to stimulate regions intermediate between the most apical electrode contact and the functional acoustic hearing region.

An Effect of Cyclosporin A in a Treatment of Temporal Bone Defect Using hBM-MSCs.

Background. The treatment of middle ear cholesteatoma requires surgical treatment and the reconstruction of the temporal bone, which represents an ongoing problem. Otologists have focused on the research of materials allowing an airy middle ear and the preservation of hearing function to reconstruct the temporal bone. Methods. This study evaluated the effect of cyclosporin A (CsA) and a combined biomaterial in the healing process of postoperative temporal bone defects in an animal model. Cultured human Bone Marrow Mesenchymal Stromal Cells (hBM-MSCs) were mixed with hydroxyapatite (Cem-Ostetic®), and subsequently applied as a bone substitute after middle ear surgery, showing that the therapeutic potential of hBM-MSCs associated with bone regeneration and replacement is directly influenced by CsA, confirming that it promotes the survival of MSCs in vivo. Results. The therapeutic efficacy of the combination of MSCs with CsA is greater than the sole application of MSCs in a hydroxyapatite carrier. Conclusion. The reconstruction of a temporal bone defect using hBM-MSCs requires an immunosuppressant to improve the results of treatment.

Safety and Efficacy of Hypofractionated Stereotactic Radiosurgery in Facial Nerve Schwannoma.

In the current era of modern neurosurgery, the treatment strategies have been shifted to "nerve-preservation approaches" for achieving a higher facial and hearing function preservation rate following facial nerve tumors. We have conducted this novel report on determining the outcome of patients with facial nerve schwannomas (FNS) treated with hypofractionated stereotactic radiosurgery (hfSRS). Retrospective chart review of a prospectively maintained database search was conducted. Patients who underwent hfSRS CyberKnife (Accuray Inc, Sunnyvale, CA, U.S.A.) for FNS were included. Outcomes consisted of tumor control, facial and hearing nerve function as graded by House-Brackmann and American Academy of Otolaryngology-Head and Neck Surgery recommendations, and adverse radiation effects. With an institutional board review approval, we retrospectively identified five patients with FNS (four intracranial [80%] and one extracranial [20%]) treated with hfSRS (2011-2019). Patients received definitive SRS in three patients (60.0%), whereas adjuvant to surgical resection in two patients (40.0%). A median tumor volume of 7.5 cm 3 (range, 1.5-19.6 cm 3 ) received a median prescription dose of 23.2 Gy (range, 21-25 Gy) administered in median of three fractions (range, three to five sessions). With a median radiographic follow-up of 31.4 months (range, 13.0-71.0 mo) and clinical follow-up of 32.6 months (range, 15.1-72.0 mo), the local tumor control was 100.0%. At the last clinical follow-up, the facial nerve function improved or remained unchanged House-Brackmann I-II in 80.0% of the patients, whereas the hearing nerve function improved or remained stable in 100.0% of the patients. Temporary clinical toxicity was observed in three patients (60.0%), which resolved. None of the patients developed adverse radiation effect. From our case series, hfSRS in FNS seems to be safe and efficacious in terms of local tumor control, and improved facial and hearing nerve function.

Pneumolabyrinth as an Early Computed Tomographic Finding After Cochlear Implantation and its Clinical Significance.

To determine the incidence and volume of pneumolabyrinth using early temporal bone computed tomography (TBCT) findings and evaluate the correlation between pneumolabyrinth and various clinical variables. Retrospective case review. Tertiary academic center. Fifty-three consecutive adult cochlear implantation (CI) recipients (53 ears) with normal inner ears who underwent high-resolution TBCT within 3 days after CI were included. Axial TBCT images were used for detection and measurement of pneumolabyrinth. Incidence and volume of pneumolabyrinth were evaluated. In addition, the following clinical variables were analyzed to evaluate the correlation with pneumolabyrinth volume: demographics, implant type, surgical approach, postoperative dizziness, and preservation of functional residual hearing. Pneumolabyrinth was present in all patients, and the average volume was 8.496 mm3. Pneumolabyrinth was confined to the cochlea (pneumocochlea) in all patients except for one who also had pneumovestibule. The pneumolabyrinth volume in patients with postoperative dizziness was significantly larger than that in patients without postoperative dizziness (10.435 mm3 vs. 8.016 mm3; p = 0.029). Multivariate analysis showed that a larger volume of pneumolabyrinth was significantly associated with postoperative dizziness (odds ratio, 1.420; 95% confidence interval, 1.114-1.808; p = 0.005). A certain volume of pneumolabyrinth was always present in the early stage after CI, and the volume of pneumolabyrinth measured using early TBCT findings was significantly associated with the occurrence of postoperative dizziness.

Initial hearing preservation outcomes of cochlear implantation with a slim perimodiolar electrode array

Objective To assess the slim modiolar array as a hearing preservation electrode. Methods Retrospective chart review of adult, post-lingual CI recipients implanted with slim modiolar array Sept 2016 to July 2017 in a tertiary referral center. Baseline audiograms were obtained within six months of initial CI evaluation. Patients with low frequency pure tone average (LFPTA) (125, 250, 500 Hz) <80 dB were considered HP candidates. Postoperative audiograms were obtained within 48 h before activation. Successful HP was considered as (1) retention of LFPTA threshold <80 dB and (2) change in threshold from pre- to post-operative. Results Sixty-three patients received the slim perimodiolar array and 42 were HP candidates. Post-operative audiograms were obtained for 39 of 42 patients an average of 28.92 days after surgery. 56.4% of HP candidates retainedLFPTA <80 dB. Mean ΔLFPTA was 24.15 dB (±16.14; p < 0.001). 56.4% of HP candidates experienced Δ LFPTA <20 dB; 69.2% <30 dB. Functional hearing preservation was more successful in lower frequencies where starting thresholds were better – 78% with LFPTA <50 dB retained serviceable hearing at activation. The postoperative change was similar in each low frequency (Δ125 Hz: mean 21.25 +/− 14.76 (N = 28); Δ250 Hz: 26.28 +/− 19.29 (N = 39); Δ500 Hz: 25.00 +/− 17.73 (N = 39)). Conclusions The slim perimodiolar array is moderately effective at immediate hearing preservation. In subjects with preoperative audiometric profiles similar to those in prior EAS trials, immediate HP is comparable.

Middle ear adenomatous neuroendocrine tumors: suggestion for surgical strategy

IntroductionMiddle ear adenomatous neuroendocrine tumors are extremely rare neoplasms with epithelial and neuroendocrine differentiation, accounting for fewer than 2% of all middle and inner ear tumors. Universal standard surgical procedures for different stages of these tumors remain elusive due to the limitation of the small number of case reports or investigations. Objective(s)This study intends to investigate proper surgical strategies for patients with middle ear adenomatous neuroendocrine tumors. MethodsSix patients with middle ear adenomatous neuroendocrine tumors who were treated at the Second Affiliated Hospital of Nanchang University (Nanchang, China) and the Eye, Ear, Nose, and Throat Hospital of Fudan University (Shanghai, China) respectively. Clinical characteristics and management strategies of patients were reviewed. The mean follow-up time was 63.7 months (range, 13–153 months). All the information was collected from medical records and prognosis postoperatively. ResultsThree patients underwent canal wall-up tympanomastoidectomy, including one patient with recurrence who underwent a previous tympanotomy; the other three patients underwent lateral temporal bone resection All of these patients were followed up with no evidence of recurrence or metastasis. Patients underwent canal wall-up surgery treatment accompanied with hearing function preservation measurements during follow-up periods. ConclusionsComplete surgical resection provided good results for patients with middle ear adenomatous neuroendocrine tumors. The ossicular chain should be removed. Because of the propensity for local recurrence and invasiveness, as well as regional or distant metastasis of these tumors, it is necessary to schedule long-term follow-up and an observation plan postoperatively.

Slim Perimodiolar Arrays Are as Effective as Slim Lateral Wall Arrays for Functional Hearing Preservation After Cochlear Implantation.

To compare functional hearing preservation (HP) with a slim perimodiolar array (SPA) and a slim lateral wall array (SLW) in cochlear implantation (CI). Retrospective chart review. Tertiary referral center. All adult, post-lingual CI recipients with serviceable preoperative hearing serially implanted with SPA or SLW electrodes from July 2015 through July 2018. Cochlear implantation. Hearing preservation (HP). Patients with a low frequency pure-tone average (LFPTA) (125, 250, 500 Hz) threshold less than 80 dB were considered HP candidates based on preoperative audiograms. Postoperative audiograms were obtained before activation. Successful HP was defined as retention of LFPTA less than 80 dB. The change in LFPTA (ΔLFPTA) was also calculated. One hundred twenty one patients were implanted with either the SPA or SLW electrodes, 82 (42,40) of whom were HP candidates with postoperative audiograms. Average (standard deviation, SD) preoperative LFPTA was 54.86 [19.38] and 54.38 [13.58] dB for SLW and SPA respectively, with a mean ΔLFPTA of 24.6 [15.94] and 24.92 [16.66] dB. Successful HP was achieved in 21 (50%) and 22 (55%). Preoperative LFTPA, ΔLFPTA, and postoperative LFPTA were not significantly different (p = 0.89, 0.75, 0.93) between electrodes. The SPA is as effective at immediate functional HP after CI as a SLW.

Short-term results of treatment outcome and toxicities following gamma knife surgery in cerebellopontine angle tumors

Introduction: About 5% to 10% of all intracranial neoplasms are located at the cerebellopontine (CP) angle. The most common of these is the vestibular schwannoma (VS). Aims and Objectives: The primary objective was to assess treatment outcomes in CP angle tumor post-Gamma Knife radiosurgery (GKS). Secondary objectives were the assessment of dose conformity and gradient indices for target coverage and organs-at-risk sparing along with the assessment of hearing function preservation post-GKS. We also assessed facial and trigeminal nerve function and quality of life (QoL) post-GKS. Materials and Methods: This was a retrospective study carried out in a tertiary care center of North India for 2 years and 3 months. All patients were followed up for 24 months posttreatment with a minimum follow-up at least 12 months. Tumor expansion was assessed post-GKS along with hearing preservation rates, facial and trigeminal nerve function and QoL. Results: No significant relationship between age, sex, and study variables was made out. The target tumor coverage ranged from 94% to 100%, with a mean of 97.24%. The conformity index ranged from 1.17 to 1.92, and the gradient index ranged from 1.35 to 1.73. Tumor expansion occurred in 52% of the patients (13) 6 months after GKS, though the increase in size was minimal with a standard deviation of 0.59 and did not result in any clinical deterioration of patients. Positive correlation was seen between maximum tumor size and loss of hearing function. The hearing preservation rate at 12 months post-GKS is 80%. This study also showed that GKS for VS has little impact in the deterioration of the function of the trigeminal and facial nerve and the general QoL. Conclusion: The radiation changes after GKS are generally seen after 6–12 months post-GKS and about 3–5 years are required to ascertain tumor control and any meaningful change in hearing levels and other toxicities. Thus, a longer period of follow-up is needed to validate the findings of this study.

Hearing Preservation and Speech Outcomes After Cochlear Implantation in Meniere's Disease.

To evaluate speech perception outcomes and hearing preservation after cochlear implantation in patients with Meniere's disease (MD). Retrospective chart review. Fifty-one adult patients, accounting for a total of 63 implants, with MD treated at a tertiary care center were included in the study. Patients with unaided preoperative air-conduction thresholds ≤80 dB at 250 Hz were included in hearing preservation analyses. The primary outcome measure was Consonant-Nucleus-Consonant (CNC) score. Hearing preservation was assessed as follows: 1) maintenance of functional hearing, defined as a postoperative unaided air-conduction threshold ≤80 dB at 250 Hz and 2) low-frequency pure-tone average (LFPTA) shift. Speech perception scores improved significantly postimplantation; specifically, the CNC mean score was 9% preoperatively and increased to 57% by 1 year postoperatively (P < .001). Eighteen ears were included in hearing preservation analysis; the mean preoperative LFPTA was 65 dB (standard deviation [SD] = 10). The mean postoperative LFPTA at activation was 93 dB (SD = 21), and at 1 year was 102 dB (SD = 11). Twenty-seven percent of patients achieved short-term functional hearing preservation, whereas the longer-term outcomes were less favorable (11%). Speech perception scores improve after implantation in patients with MD. Hearing preservation is possible in patients with MD, albeit at lower rates than reported non-MD populations. Our data suggest that there can be degradation in acoustic hearing over time. 4 Laryngoscope, 2019.

Radiotherapy in patients with vestibular schwannoma and neurofibromatosis type 2: clinical results and review of the literature.

To evaluate the long-term outcome of patients with vestibular schwannoma (VS) and neurofibromatosis type 2 (NF2) treated with fractionated stereotactic radiotherapy (FSRT) or stereotactic radiosurgery (SRS). Sixteen VS in 14 patients with NF2 were treated with FSRT (n = 14) and SRS (n = 2). Patients with tumor progression and/or progression of clinical symptoms were selected for treatment. For patients treated with FSRT a median total dose of 57.6 Gy was prescribed with a median fractionation of 5 × 1.8 Gy per week. For patients who underwent SRS a median single dose of 17 Gy was prescribed to the 80% isodose. FSRT and SRS were well tolerated. Local control rate was 94% for a median follow-up time of 131 months; 2- and 5-year progression-free survival were 100%. The probability of maintaining the pretreatment hearing level was 44%. Useful hearing preservation was 33%. Cranial nerve toxicity was moderate. Trigeminal nerve function worsened in 2 patients (12%) and facial nerve function in 3 patients (19%). One patient developed a new tinnitus. FSRT and SRS are both safe and effective noninvasive and minimally invasive treatment options for patients with VS in the setting of NF2. The long-term local control rates are excellent. Functional hearing preservation is worse in patients with VS and NF2 than in patients with sporadic VS.

Hearing Preservation Cochlear Implantation: a Review of Audiologic Benefits, Surgical Success Rates, and Variables That Impact Success

The objectives of this review are as follows: (1) examine the audiologic benefits of hearing preservation, (2) review rates of successful hearing preservation, and (3) analyze variables that impact hearing preservation success. Hearing preservation has been shown to confer the following audiologic benefits: better speech understanding in complex listening environments, superior sound localization, and improved music appreciation. There is a notable lack of standardized criteria for reporting of hearing preservation outcomes—this leads to considerable heterogeneity across studies. Rates of functional (i.e., aidable) hearing preservation generally range between 50 and 90%. Studies demonstrate higher preservation rates and more durable hearing outcomes with shorter, straight electrode arrays. With advances in CI technology and surgical techniques, residual hearing can be preserved after CI surgery in the majority of patients. Cochlear implant recipients with preserved hearing demonstrate better speech understanding, sound localization, and improved music appreciation.

Predictive factors for short- and long-term hearing preservation in cochlear implantation with conventional-length electrodes.

The aims of this study were to investigate short- and long-term rates of hearing preservation after cochlear implantation and identify factors that impact hearing preservation. Retrospective review. Patients undergoing cochlear implantation with conventional-length electrodes and air-conduction thresholds ≤80 dB HL at 250 Hz preoperatively were included. Hearing preservation was defined as air-conduction thresholds ≤80 dB HL at 250 Hz. The sample included 196 patients (225 implants). Overall, the rate of short-term hearing preservation was 38% (84/225), with 18% (33/188) of patients preserving hearing long term. Multivariate analysis showed better preoperative hearing was predictive of hearing preservation at short (odds ratio [OR]: 0.93, 95% confidence interval [CI]: 0.91-0.95, P < .001) and long-term follow-up (OR: 0.94, 95% CI: 0.91-0.97, P < .001). Lateral wall electrodes and mid-scala electrodes had 3.4 (95% CI: 1.4-8.6, P = .009) and 5.6-times (95% CI: 1.8-17.3, P = .003) higher odds of hearing preservation than perimodiolar arrays at short-term follow-up, respectively. Long-term data revealed better hearing preservation for lateral wall (OR: 7.6, 95% CI: 1.6-36.1, P = .01), but not mid-scala (OR: 3.1, 95% CI: 0.4-23.1, P = .28), when compared to perimodiolar electrodes. Round window/extended round window (RW/ERW) approaches were associated with higher rates of long-term hearing preservation (21%) than cochleostomy approaches (0%) (P = 0.002) on univariate analysis. Better preoperative residual hearing, lateral wall electrodes, and RW/ERW approaches are predictive of higher rates of long-term functional hearing preservation. 4. Laryngoscope, 128:482-489, 2018.

Gamma Knife Radiosurgery as Primary Treatment for Large Vestibular Schwannomas: Clinical Results at Long-Term Follow-Up in a Series of 59 Patients

Gamma Knife radiosurgery (GKRS) represents a well-accepted treatment for small-medium vestibular schwannomas (VS); however, its application in larger VS is still controversial. Among the 523 patients treated at our institution for VS between 2001 and 2010, we included 59 patients with a VS larger than 25 mm, treated by GKRS as primary treatment, not affected by neurofibromatosis type 2, and with a clinical follow-up of at least 36 months. Five patients underwent ventriculoperitoneal shunt placement before radiosurgery. Clinical follow-up (mean, 79.4 months) was obtained in all patients. Patients' age ranged from 24 to 85 years (mean, 63.8 years). Mean tumor volume was 5.98 cm3 (maximum, 14.3 cm3) and median marginal dose was 13 Gy. A statistical analysis was performed to correlate clinical outcome with tumor radiologic features, dose-planning parameters, and patients' characteristics. Tumor control was achieved in 98.3% of cases. At last follow-up, 86.4% of VS showed volume reduction. Recorded complications were 3 cases (5.1%) of new permanent facial nerve deficit, 4 cases (6.8%) of new or worsened trigeminal impairment, and 10 new cases (18.5%) of hydrocephalus requiring ventriculoperitoneal shunt. Larger tumor size was significantly associated with a subsequent ventricular enlargement. Overall, functional hearing preservation rate was 31.3% (66.7% among patients with Gardner-Robertson I). Surgical resection remains the primary approach for large VS with symptomatic brainstem compression. GKRS can be considered a safe and effective option in particular in patients who are not good candidates for surgery.

Long-term results of Gamma-knife stereotactic radiosurgery for vestibular schwannomas in patients with type 2 neurofibromatosis

IntroductionThe aim of this study was to analyze the long-term results of Gamma-knife radiosurgery treatment of vestibular schwannomas in type 2 neurofibromatosis patients. Materials and methodsA cohort of 129 treatments for vestibular schwannomas in 103 patients was selected from a prospectively-maintained clinical database. Tumor control was assessed by volumetric analysis of the tumor at the last follow-up. Any need of a further procedure such as microsurgical removal or second treatment was regarded as a failure of tumor control. Hearing function was assessed based on Gardner-Robertson classification. Progression-free survival and functional hearing preservation rates were estimated using the Kaplan-Meier method. ResultsThe median age at treatment was 34 years with no gender predominance. The median tumor volume was 1.5cm3. At a median clinical follow-up of 5.9 years, five patients had died, four underwent a second radiosurgical procedure and eight underwent microsurgical resection. Progression-free survival was 88 and 75% respectively at 5 and 10 years. Hearing was considered serviceable in 70 ears and remained functional in 28 ears. Kaplan-Meier estimates for 5 and 10 years functional hearing was 47 and 34%, respectively. Three patients developed new facial nerve palsy after radiosurgery at 15 days, 6 and 19 months respectively and only one partially recovered. Five patients complained of a subjective instability worsening. Four cases developed trigeminal neuropathy. No predictive factors were found to be statistically correlated with a better hearing outcome or an improved tumor growth control. ConclusionResults prove less satisfying than in sporadic unilateral schwannomas. However, the lower rate of mortality and morbidity compared with microsurgical resection may support a proactive role of Gamma-knife in this pathology.

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.

Vestibular Schwannoma: The Evolution of Hearing and Tumor Size in Natural Course and after Treatment by LINAC Stereotactic Radiosurgery

Objective: To review the natural course of tumor size and hearing during conservative management of 151 patients with unilateral vestibular schwannoma (VS), and to evaluate the same parameters for the part of the group (n = 84) who were treated by LINAC stereotactic radiosurgery (SRS). Methods: In prospectively collected data, patients underwent MRI and complete audiovestibular tests at inclusion, during the conservative management period and after SRS. Hearing was graded according to the Gardner-Robertson (GR) scale and tumor size according to Koos. Statistics were performed using Kaplan-Meier survival analysis and multivariate analyses including linear and logistic regression. Specific insight was given to patients with serviceable hearing. Results: During the conservative management period (mean follow-up time: 24 months, range: 6-96), the annual risk of GR class degradation was 6% for GRI and 15% for GR II patients. Hearing loss as an initial symptom was highly predictive of further hearing loss (p = 0.003). Tumor growth reached 25%. For SRS patients, functional hearing preservation was 51% at 1 year and 36% at 3 years. Tumor control was 94 and 91%, respectively. Conclusion: In VS patients, hearing loss at the time of diagnosis is a predictor of poorer hearing outcome. LINAC SRS is efficient for tumor control. Patients who preserved their pretreatment hearing presented less hearing loss per year after SRS than before treatment, suggesting a protective effect of SRS when cochlear function can be preserved.

Diagnosis and treatment of cavernous hemangioma of the internal auditory canal.

Cavernous hemangioma of the internal auditory canal (IAC) is an extremely rare type of tumor, and only 50 cases have been reported in the literature prior to this study. The aim in this study was to describe the symptomatology, radiological features, and surgical outcomes for patients with cavernous hemangioma of the IAC and to discuss the diagnostic criteria and treatment strategy for the disease. The study included 6 patients with cavernous hemangioma of the IAC. All patients presented with sensorineural hearing loss and tinnitus, and 2 also suffered from vertigo. Five patients reported a history of facial symptoms with hemispasm or palsy: 3 had progressive facial weakness, 1 had a hemispasm, and 1 had a history of recovery from sudden facial paresis. All patients underwent CT and MRI to rule out intracanalicular vestibular schwannomas and facial nerve neuromas. Five patients had their tumors surgically removed, while 1 patient, who did not have facial problems, was followed up with a wait-and-scan approach. All patients had a presurgical diagnosis of cavernous hemangioma of the IAC, which was confirmed pathologically in the 5 patients who underwent surgical removal of the tumor. The translabyrinthine approach was used to remove the tumor in 4 patients, while the middle cranial fossa approach was used in the 1 patient who still had functional hearing. Tumors adhered to cranial nerves VII and/or VIII and were difficult to dissect from nerve sheaths during surgeries. Complete hearing loss occurred in all 5 patients. In 3 patients, the facial nerve could not be separated from the tumor, and primary end-to-end anastomosis was performed. Intact facial nerve preservation was achieved in 2 patients. Patients were followed up for at least 1 year after treatment, and MRI showed no evidence of tumor regrowth. All patients experienced some level of recovery in facial nerve function. Cavernous hemangioma of the IAC can be diagnosed preoperatively through analysis of clinical features and neuroimaging. Early surgical intervention may preserve the functional integrity of the facial nerve and provide a better outcome after nerve reconstruction. However, preservation of functional hearing may not be achieved, even with the retrosigmoid or middle cranial fossa approaches. The translabyrinthine approach seems to be the most appropriate approach overall, as the facial nerve can be easily located and reconstructed.