Intracanalicular Vestibular Schwannoma Research Articles

Tumor shape as a prognostic factor for the growth of intracanalicular vestibular schwannoma: a long-term observational study.

To evaluate the predictive factors of tumor growth in patients with vestibular schwannoma (VS) managed with the wait-and-scan approach. The data of 31 patients diagnosed with intracanalicular VS and followed for > 5years were retrospectively analyzed. VS was diagnosed according to MRI findings and tumor growth was monitored. Tumor growth was defined as an increase of 2mm or more in the maximal tumor diameter. The association between the initial tumor size and shape and tumor growth was assessed. Tumor growth was observed in 16 of 31 patients (51.6%) over a mean follow-up duration of 7.3years. The initial tumor size was not statistically correlated with tumor growth. However, fusiform or cylindrical tumors exhibited higher growth rates than oval or round tumors. Additionally, a significant correlation was observed between cerebellopontine angle extension and tumor shape. In this study, 51.6% of the patients with intracanalicular VS who were managed with the wait-and-scan strategy over a follow-up period of > 5years showed tumor growth. Tumor shape, especially fusiform or cylindrical shape, was found to be a significant predictor of tumor growth.

Hearing Outcomes from Gamma Knife Treatment for Intracanalicular Vestibular Schwannomas with Good Initial Hearing.

Background: The objective of this study was to describe the long-term hearing outcomes of gamma knife treatment for unilateral progressing vestibular schwannomas (VS) presenting with good initial hearing using audiologic data. Methods: A retrospective review was performed between 2010 and 2020 to select patients with progressing unilateral VS and good hearing (AAO-HNS class A) treated with stereotactic gamma knife surgery (GKS). Their audiograms were analyzed along with treatment metrics and patient data. Results: Hearing outcomes with a median follow-up of 5 years post-treatment showed statistically significant loss of serviceable hearing: 34.1% of patients maintained good hearing (AAO-HNS class A), and 56.1% maintained serviceable hearing (AAO-HNS class A and B). Non-hearing outcomes are favorable with excellent tumor control and low facial nerve morbidity. Conclusions: Hearing declines over time in intracanalicular VS treated with GKS, with a significant loss of serviceable hearing after 5 years. The mean cochlear dose and the presence of cochlear aperture obliteration by the tumor are the main statistically significant factors involved in the hearing outcomes.

Hearing preservation after stereotactic radiosurgery for sporadic intracanalicular vestibular schwannomas classified as Koos grade 1.

The mechanism of hearing loss following stereotactic radiosurgery (SRS) for vestibular schwannomas (VSs) remains unclear. There is conflicting evidence regarding cochlear nerve damage by transient volume expansion of VSs after radiosurgery and radiation-induced cochlear damage. This study aimed to investigate whether there is a specific patient population that can achieve definite hearing preservation after SRS for VSs. A total of 37 consecutive patients with sporadic unilateral intracanalicular VSs and serviceable hearing (Gardner-Roberson [G-R] class I or II) were treated with SRS from 2009 to 2023. This is a retrospective study. Survival analysis with Cox regression for hearing deterioration was performed. The median age was 55 years old. The median tumor volume was 0.089 cm3 , and the median marginal dose was 12.0 Gy. Nonserviceable hearing deterioration occurred in 9 patients (24.3%), with a median onset of 11.9 months after SRS. The actuarial rates of serviceable hearing preservation were 86%, 82%, and 70% at 1, 2, and 3 years after SRS, respectively. In a multivariate analysis, only baseline pure tone average > 30 dB increased the risk of nonserviceable hearing deterioration with significant hazard ratio. There were 13 patients with petit VSs whose tumor volume was smaller than 0.05 cm3 , and 11 of them were treated by a 4-mm single shot with a marginal dose of 12 Gy. None of the 13 patients had nonserviceable hearing deterioration. Petit VSs that can be treated with 4-mm single or double shots with a marginal dose of 12 Gy may achieve hearing preservation after SRS.

Management of sporadic intracanalicular vestibular schwannomas: A critical review and International Stereotactic Radiosurgery Society (ISRS) practice guidelines.

The choice of an appropriate strategy for intracanalicular vestibular schwannoma (ICVS) is still debated. We conducted a systematic review and meta-analysis with the aim to compare treatment outcomes amongst management strategies (conservative surveillance (CS), microsurgical resection (MR), or stereotactic radiosurgery (SRS)) aiming to inform guideline recommendations on behalf of the International Stereotactic Radiosurgery Society (ISRS). Using PRISMA guidelines, we reviewed manuscripts published between January 1990 and October 2021 referenced in PubMed or Embase. Inclusion criteria were peer-reviewed clinical studies or case series reporting a cohort of ICVS managed with CS, MR, or SRS. Primary outcome measures included tumor control, the need for additional treatment, hearing outcomes, and posttreatment neurological deficits. These were pooled using meta-analytical techniques and compared using meta-regression with random effect. Forty studies were included (2371 patients). The weighted pooled estimates for tumor control were 96% and 65% in SRS and CS series, respectively (P < .001). Need for further treatment was reported in 1%, 2%, and 25% for SRS, MR, and CS, respectively (P = .001). Hearing preservation was reported in 67%, 68%, and 55% for SRS, MR, and CS, respectively (P = .21). Persistent facial nerve deficit was reported in 0.1% and 10% for SRS and MR series, respectively (P = .01). SRS is a noninvasive treatment with at least equivalent rates of tumor control and hearing preservation as compared to MR, with the caveat of better facial nerve preservation. As compared to CS, upfront SRS is an effective treatment in achieving tumor control with similar rates of hearing preservation.

Intracanalicular vestibular schwannomas: facial and hearing outcomes according to the location of the tumor in relation to the nerves of the internal auditory canal.

The objective was to evaluate whether the position of the nerves within the internal auditory canal (IAC) has any effect on preoperative and postoperative cochlear and facial nerve function in patients with intracanalicular vestibular schwannoma (VS) resected through the retrosigmoid transmeatal approach. Forty-four patients with sporadic intracanalicular VS, from a series of 710 patients with VS who underwent operations from January 1993 to April 2022, were retrospectively reviewed. The pattern of displacement of the cranial nerves and tumor within the IAC was recorded. Tumors were divided into 2 types: type T1A lesions had only anteriorly displaced nerves, and type T1B had posteriorly displaced vestibular nerves and anteriorly displaced facial and cochlear nerves. Differences in surgical outcomes between groups in terms of facial nerve function and hearing preservation were evaluated. Thirty-five cases (79.5%) were T1A tumors and 9 were T1B (20.5%). Gross-total resection and anatomical preservation of the facial and cochlear nerves were achieved in all patients. Postoperatively, all patients with T1A VS maintained normal facial nerve function; however, among T1B VS patients, 6 (67%) retained House-Brackmann grade I, 2 worsened to grade II, and 1 worsened to grade III at 6 months (p = 0.006). The 27 T1A VS patients with serviceable hearing maintained this status, and an additional patient with nonserviceable hearing improved to serviceable hearing; among T1B VS patients, only 2 of the 5 patients with serviceable hearing remained as such, 2 evolved to nonserviceable hearing, and 1 lost hearing after surgery (p = 0.0022). T1B VS patients had a 24-fold risk of facial nerve deterioration (relative risk [RR] 25.2, 95% CI 1.42-448.57, p = 0.028) and a 32-fold risk of hearing deterioration (RR 32.7, 95% CI 1.93-553, p = 0.016) after surgery. In intracanalicular VS, postoperative cochlear and facial nerve function are directly related to the location of the tumor in relation to the nerves, with worse outcomes in cases where the tumor is located between the vestibular and facial-cochlear nerves.

Outcomes and Prognostic Factors in the Treatment of Intracanalicular Vestibular Schwannomas Using Gamma Knife Stereotactic Radiation.

No gold standard has been developed for the therapy of intracanalicular vestibular schwannomas (IVS). Options for treatment include a conservative approach, microsurgery, or radiosurgery. Although the efficacy of these treatment has been well-documented, little is known about the determinants of outcome in IVSs following radiosurgery. Therefore, we examined the results in relation to age, gender, tumor volume, distance to fundus, microcyst existence, and radiosensitivity in this group. In addition, we investigated possible predictors of facial nerve function and hearing preservation. Ninety-four patients with unilateral IVS were included in the evaluation (52 women and 42 males). The patients were separated into younger and older age groups based on their median age (55 years). The median IVS volume was 138 mm3, microcysts were identified in 16 tumors, and 63 tumors were adjacent to the fundus. The data were analyzed using Statistica software package ver. 13.3. At final follow-up, a statistically significant decrease in tumor volume and no statistically significant decline in hearing were noted, but no differences between age groups were found. The sex had no effect on overall tumor growth control, facial nerve preservation, or hearing preservation. Localization of IVS close to the fundus and the presence of tumor microcysts had no effect on the control of tumor growth, preservation of hearing, and sparing of facial nerve following radiosurgery. Cochlear dose had no influence on hearing preservation. Higher tumor volume was associated with its pseudoprogression during early follow-up and a greater risk of hearing loss. Age, sex, tumor volume, proximity to the fundus, and the existence of a microcyst were not predictive of radiosensitivity nor preservation of facial nerve function and hearing, based on the findings. There was no effect of cochlear dose on hearing. Initial greater tumor volume was associated with an increased probability of tumor pseudoprogression.

Cochlear Implantation Following Transcanal Infrapromontorial Approach for Vestibular Schwannoma: A Case Series.

Background: Cochlear implantation (CI) following endoscopic transcanal infrapromontorial vestibular schwannoma (VS) dissection is a feasible intervention in intracanalicular VS, with minimal extension into the cerebellopontine angle, but no audiologic results have ever been reported in the literature. Methods: From 2015 to 2021 in the Otorhynolaryngology Departments of Modena and Verona, three patients underwent this intervention. All were suffering from sporadic left-sided intracanalicular Koos I VS. Intraoperative electrically evoked auditory brainstem responses and electrophysiological measurements were performed before and after the placement of the electrode array, respectively. Since device activation one month after the surgery, each patient was followed up with audiometric tests, data logging, electrode impedance measurements and neural response telemetry performed at each scheduled fitting session at 15 days and 3, 6, 12 and 24 months. Results: Only in patient No. 3, an auditory benefit was observed and still evident even 36 months after activation. Impedances increased progressively in patient No. 1 and a benefit was never reported. Patient No. 2 left the follow-up for worsening comorbidities. Conclusions: CI following transcanal infrapromontorial VS resection is a beneficial intervention. The residual cochlear nerve after the tumour dissection and the course of electrophysiological measurements in the postoperative period were the main predictive factors for audiological outcomes.

Wait and Scan Management of Intra-canalicular Vestibular Schwannomas: Analysis of Growth and Hearing Outcome

To report on the results of intracanalicular vestibular schwannomas (ICVS) that were managed by wait and scan and to analyze the possible predictors of tumor growth and hearing deterioration throughout the observation period. A retrospective case series. Quaternary referral center for skull base pathologies. Patients with sporadic ICVS managed by wait and scan. Serial resonance imaging (MRI) with size measurement and serial audiological evaluation. Tumor growth defined as 2 mm increase of maximal tumor diameter, further treatment, and hearing preservation either maintain initial modified Sanna hearing class, or maintain initial serviceable hearing (class A/B). 339 patients were enrolled. The mean follow-up was 36.5±31.7 months with a median of 24 months. Tumor growth occurred in 141 patients (40.6%) either as slow growth (SG) in 26.3% of cases or fast growth (FG) in 15.3% of cases. Intervention was performed in only 64 cases (18.8%). Out of 271 patients who underwent hearing analysis, 86 patients (33.5%) showed hearing deterioration to a lower hearing class of the modified Sanna classification. Tumor growth and older age were predictors of hearing deterioration. Of the 125 cases with initial serviceable hearing (Class A/B), 91 cases (72.8%) maintained serviceable hearing at last follow-up. Tumor growth and a worse initial pure tone average (PTA) were predictors of hearing deterioration. Wait and scan management of ICVS is a viable option and only 18.8% of patients needed further treatment. Hearing tends to deteriorate over time.

Endoscopic-Assisted Keyhole Middle Cranial Fossa Approach for Small Vestibular Schwannomas.

The classical middle cranial fossa approach (MCFA) for vestibular schwannoma (VS) removal often requires a large incision and craniotomy, excessive temporal lobe manipulation, and a longer recovery. We describe a keyhole MCFA (KMCFA) with endoscopic assistance that allows for adequate access with minimal temporal lobe manipulation, resulting in a fast recovery and an invisible scar. Eight sides of four cadaveric heads were dissected through the endoscopic-assisted KMCFA to access the internal auditory canal (IAC). Furthermore, five patients with intracanalicular VS underwent tumor removal with the endoscopic-assisted KMCFA. During the endoscopic-assisted KMCFA with fine instruments, a 3-cm supra-auricular incision and a 2-cm diameter keyhole craniotomy achieved exposure of the entire length of the IAC in all cadaveric dissections without unintended violation of the cochlea, semicircular canal, and facial nerve. The gross tumor was totally removed in five patients with no major postoperative complications. The surgical time was reduced, the hearing outcomes were similar to those of the classical MCFA, and the scar was invisible 1 month after the surgery. The endoscopic-assisted KMCFA permits intracanalicular VS removal in a safe, efficient, and cosmetic way. For small intracanalicular VSs, this approach can replace the classical MCFA when indicated.

Extended middle fossa approach for resection of a petroclival meningioma and vestibular schwannoma

A 69-year-old woman with refractory left facial pain and subtle left hearing decline had a 13.0 × 8.1–mm left petrous apex/Meckel’s cave meningioma and an 8.8 × 5.6–mm left intracanalicular vestibular schwannoma. She was otherwise neurologically intact. The anterior petrous and middle fossa approaches provide ideal access to these lesions individually, so an extended middle fossa approach was used to resect both in the same setting. She was neurologically stable postoperatively, except for a transient abducens palsy. Hearing was preserved on audiogram, and 4-month MRI displayed no tumors. The extended middle fossa approach provides excellent exposure of the petrous apex and internal auditory canal.The video can be found here: https://stream.cadmore.media/r10.3171/2022.1.FOCVID21258

The Natural History of Small Vestibular Schwannomas.

ObjectiveThe incidence of vestibular schwannomas is increasing, and the average tumor size at diagnosis is decreasing. Therefore, understanding the specific growth pattern of small vestibular schwannomas is becoming increasingly important to guide clinical management. The objectives of this study were to evaluate the growth patterns of very small intracanalicular vestibular schwannomas measuring ≤ 4 mm in linear diameter and to assess the likelihood of these lesions ever requiring treatment. MethodsA retrospective review was performed. A search of all MRI brain and internal auditory canal studies suggestive of a vestibular schwannoma from 1995 to 2019 was performed at our institution. This resulted in 372 cases, which were then evaluated for the presence of a vestibular schwannoma measuring ≤ 4 mm. All patients had to have at least one follow-up MRI to be included. Images were reviewed by a neuroradiologist.ResultsEight ≤ 4 mm vestibular schwannomas were found that met all search criteria. The distribution of tumor sizes was as follows: three 2 mm, one 3 mm and four 4 mm. None of the ≤ 4 mm vestibular schwannomas identified demonstrated any significant growth in the linear dimension defined as greater than 2 mm of growth over observation times of 1-13 years (mean 6.3 years). None of the lesions ever required a treatment intervention per available medical records.ConclusionNone of the ≤ 4 mm intracanalicular vestibular schwannomas identified in this study grew significantly or required treatment. Overall, the findings in this study suggest that vestibular schwannomas measuring ≤ 4 mm are unlikely to grow and ever require treatment.

A Subset of Intracanalicular Vestibular Schwannomas Demonstrates Minimal Growth Over a 10-Year Period.

Vestibular schwannomas (VS) commonly undergo magnetic resonance imaging (MRI) surveillance, but long-term data to support the ideal frequency is limited. Herein, we aim to investigate intracanalicular VS growth predictors and long-term growth rates (GR). Retrospective chart review. Two tertiary care centers. Sporadic intracanalicular VS with initial conservative management and at least two sequential MRIs. Serial MRI. VS were categorized by baseline internal auditory canal tertile sublocalization (fundus, midpoint, porus) and size (≤100, 100-200, >200 mm3). Throughout follow-up, volumetric GR (mm3/yr) were determined (baseline-3 yrs, 3-5 yrs, 5-10 yrs) and treatment rates were assessed. Ninety-nine intracanalicular VS were identified (mean follow-up of 6.1 ± 4.5 yrs). Mean GR before 5-year follow-up were comparable for baseline tertile involvement and size. After 5-year follow-up, mean GR of VS involving the fundus at baseline were lower than those involving the midpoint and fundus (6.17 ± 21.16 and 119.74 ± 117.57 mm3/yr, respectively; p = 0.034). Mean GR of VS with less than or equal to 100 mm3 at baseline (-7.29 ± 25.44 mm3/yr) were lower than those with 100 to 200 mm3 (86.55 ± 103.99 mm3/yr; p = 0.011) and more than 200 mm3 (45.70 ± 35.71 mm3/yr; p = 0.031). Vestibular schwannomas involving the midpoint and fundus had greater treatment rates compared with VS involving only the fundus (p < 0.001). Baseline tertile involvement and size may predict long-term intracanalicular VS growth where fundal tumors or those less than or equal to 100 mm3 exhibit little long-term growth. Extending surveillance after 5-year follow-up may be reasonable for fundal VS.

Tumor control and hearing preservation after radiosurgery of intracanalicular vestibular schwannomas - systematic review.

Intracanalicular vestibular schwannomas (IVS) account for 8% of all vestibular schwannomas and their detection is still increasing due to high availability of magnetic resonance (MRI). Radiosurgery is one of several commonly acceptable methods of IVS treatment, but some risk may still exist with that treatment. The aim of this study is to analyze the clinical outcomes in tumor control and hearing preservation after radiosurgery of IVS. The retrospective analysis included 14 scientific papers available in the PubMed database. Assessment of tumor volume was performed based on gadolinium-enhanced T1-weighted scans. Hearing preservation was assessed using the Gardner-Robertson classification (GR class). Statistical analysis was performed using IBM SPSS Statistics 27. It was revealed that tumor growth control in IVS treated with radiosurgery was higher than in the wait-and-see strategy. The hearing preservation was similar in patients after wait and see and the surgical group. Radiosurgery was associated with low risk of facial nerve dysfunction.

A Case-Case Analysis of Intralabyrinthine Schwannoma Versus Intracanalicular Vestibular Schwannoma.

Determine the differences in presentation of intracanalicular and intralabyrinthine schwannomas. Retrospective chart review at a single center. Tertiary academic referral center. Eighteen subjects with an intralabyrinthine schwannoma (ILS) and 216 patients with an intracanalicular vestibular schwannoma (VS). Variables collected included age at diagnosis, gender, presenting signs and symptoms, imaging findings, treatment modality, pure-tone average (PTA), and word recognition scores (WRS) at presentation and at follow-up visits. Incidence of subjective hearing loss was 100% in the ILS group and 80.6% in the intracanalicular VS group. The degree of hearing loss was significantly worse in the ILS group (average PTA of 83.9 dB; average WRS of 46.9%) compared with the VS group (average PTA of 38.7 dB; average WRS of 71.8%) (PTA p = 0.000006; WRS p = 0.007). Other subjective signs and symptoms, including vestibular symptoms, did not differ significantly between the two groups. Approximately one-third of both groups underwent microsurgical resection. 22.2% of ILSs were missed on initial imaging by radiologists. Intralabyrinthine schwannomas differ from intracanalicular schwannomas in the severity of hearing loss at presentation. Otherwise, these two tumors present in a very similar fashion-age at presentation, presenting signs and symptoms-and are treated comparably. Otolaryngologists should maintain a high degree of suspicion for ILS in patients presenting with an asymmetric hearing loss, vertigo, and tinnitus.

Resection of Vestibular Schwannoma Through Middle Cranial Fossa Approach with Endoscopic Assistance

We sought to report the outcome of resection of vestibular schwannomas (VSs) originating from the inferior vestibular nerve that extended into the fundus of the internal auditory canal through the middle cranial fossa (MCF) approach with endoscopic assistance. Seven patients with VSs who underwent resection through MCF approach with endoscope assistance and 12 patients with conventional microsurgery in our department were enrolled in this study. These patients' characteristics were acquired, and the surgical outcomes, as well as postoperative complications, were evaluated. In the endoscope group, the VS was first removed by a conventional microscopic procedure and then an endoscope was used to find and remove any residue lesions. In 3 of 7 patients, residue tumor in the space below transverse crest was found and completely removed under endoscope. Six of 7 patients (85.7%) had House-Brackmann grade I at the time of last follow-up in the endoscope group compared with 10 of 12 patients (83.3%) in the conventional microsurgery group. Serviceable hearing was successfully maintained in 2 of 3 patients (66.7%) in the endoscope group compared with 6 of 10 patients (60%) in the conventional microsurgery group. Total resections were achieved in all the patients (100%) in the endoscope group compared with 9 of 12 patients (75%) in the conventional microsurgery group. Using an endoscope in VS resection through the MCF approach could facilitate complete removal of the lesion while minimizing the risk of hearing loss and facial paralysis. The endoscope-assisted MCF approach is especially suitable for removing an intracanalicular VS with lateral extension involving the space below the transverse crest.

Stereotactic radiosurgery as the first-line treatment for intracanalicular vestibular schwannomas.

This report evaluates the outcomes of stereotactic radiosurgery (SRS) as the first-line treatment of intracanalicular vestibular schwannomas (VSs). Between 1987 and 2017, the authors identified 209 patients who underwent SRS as the primary intervention for a unilateral intracanalicular VS. The median patient age was 54 years (range 22-85 years); 94 patients were male and 115 were female. Three patients had facial neuropathy at the time of SRS. One hundred fifty-five patients (74%) had serviceable hearing (Gardner-Robertson [GR] grades I and II) at the time of SRS. The median tumor volume was 0.17 cm3 (range 0.015-0.63 cm3). The median margin dose was 12.5 Gy (range 11.0-25.0 Gy). The median maximum dose was 24.0 Gy (range 15.7-50.0 Gy). The progression-free survival rates of all patients with intracanalicular VS were 97.5% at 3 years, 95.6% at 5 years, and 92.1% at 10 years. The rates of freedom from the need for any additional intervention were 99.4% at 3 years, 98.3% at 5 years, and 98.3% at 10 years. The serviceable hearing preservation rates in GR grade I and II patients at the time of SRS were 76.6% at 3 years, 63.5% at 5 years, and 27.3% at 10 years. In univariate analysis, younger age (< 55 years, p = 0.011), better initial hearing (GR grade I, p < 0.001), and smaller tumor volumes (< 0.14 cm3, p = 0.016) were significantly associated with improved hearing preservation. In multivariate analysis, better hearing (GR grade I, p = 0.001, HR 2.869, 95% CI 1.569-5.248) and smaller tumor volumes (< 0.14 cm3, p = 0.033, HR 2.071, 95% CI 1.059-4.047) at the time of SRS were significantly associated with improved hearing preservation. The hearing preservation rates of patients with GR grade I VS were 88.1% at 3 years, 77.9% at 5 years, and 38.1% at 10 years. The hearing preservation rates of patients with VSs smaller than 0.14 cm3 were 85.5% at 3 years, 77.7% at 5 years, and 42.6% at 10 years. Facial neuropathy developed in 1.4% from 6 to 156 months after SRS. SRS provided sustained tumor control in more than 90% of patients with intracanalicular VS at 10 years and freedom from the need for additional intervention in more than 98% at 10 years. Patients with initially better hearing and smaller VSs had enhanced serviceable hearing preservation during an observation interval up to 10 years after SRS.

Hearing preservation middle fossa approach for intracanalicular vestibular schwannoma in a NF2 patient.

Hearing preservation is a cornerstone in the management of intracanalicular vestibular schwannomas. This video demonstrates a middle fossa approach to an intracanalicular schwannoma and highlights some technical and anatomical nuances relevant to the procedure. The patient had sustained hearing preservation in the postoperative period. There are potential benefits in favor of the middle fossa when the tumor reaches the fundus of the internal auditory canal, but the surgeon’s individual experience plays a decisive role in the choice of approach.The video can be found here: https://stream.cadmore.media/r10.3171/2021.7.FOCVID21121

"Save the Nerve": Technical Nuances for Hearing Preservation and Restoration in Vestibular Schwannoma Surgery: 2-Dimensional Operative Video.

Hearing loss is a significant disability that inflects dysfunction and affects the patient quality of life. Consequently, hearing preservation and the potential of hearing restoration are prized quests in the management of vestibular schwannoma.1 Although small intracanalicular vestibular schwannomas are commonly observed, progressive hearing loss occurs despite the absence of tumor growth; hence, surgical resection can be performed with the sole aim of hearing preservation in well-informed and eager patients. Hearing preservation by surgical resection has proven to be durable.1-4 In this group of patients, we concur with Yamakami et al2 that vascularized meatal flap to reconstruct the canal helps prevent scarring of the cochlear nerve and provides cerebrospinal fluid (CSF) bathing to the cochlear nerve, yielding better long-term hearing preservation. With larger tumors and more severe hearing loss at presentation, microsurgical resection should aim at preserving the cochlear nerve, a goal frequently achievable, which offers the potential for hearing restoration with cochlear implants.3 The results of cochlear implants in restoration of severe hearing loss have been to say the least most impressive.5 We demonstrate these 2 frequently encountered clinical situations with 2 surgical videos showing specific surgical tenets, including intra-arachnoidal dissection, medial to lateral manipulation of the tumor, preservation of the labyrinthine artery, as well as reconstruction of the internal auditory canal.2,3,6,7 The patients consented to the surgery and to the publication of their picture in a surgical video. Illustration in video © 1997 O. Al-Mefty. Used with permission. All rights reserved.

Endoscopic intracanalicular vestibular schwannoma excision via middle ear corridors a surgical options

Background With more intracanalicular vestibular schwannoma (ICVS) diagnosed, treatment options are limited either to wait-and-see or surgery. The transpromontorial and infrapromontorial approaches allow direct route to the fundus of internal auditory canal with certain advantages in preserving facial nerve and even cochlear nerve. Objectives To describe the middle ear corridor approach for ICVS excision. Methodology All transpromontorial and infrapromontorial approaches for ICVS excision were recruited. The surgeries were performed at an otologic center by a single experienced otologist. Results Three cases of ICVS Koos Type I were included in this review. Two cases were operated with exclusive endoscopic transcanal transpromontorial approach excision of tumor. One case underwent concurrent transcanal excision of ICVS through infrapromontorial approach with cochlear implantation. Two of them developed facial nerve paresis. The last patient recovered fully with viable cochlear nerve enabling hearing restoration with cochlear implant. Conclusion The potential of surgery in ICVS via middle ear approach is a safe and direct route with promising outcome. This approach offers removal of the ICVS without interrupting facial and cochlear nerves. Hence, the preservation of facial function and hearing are possible.

Evaluation of Brainstem Subcortical Auditory Pathways with Diffusion Tensor Imaging After Gamma Knife Radiosurgery in Intracanalicular Vestibular Schwannoma.

ObjectiveTo investigate changes in DTI (Diffusion Tensor Imaging) parameters in brainstem subcortical auditory pathways after Gamma Knife Radiosurgery (GKR) in patients with intracanalicular vestibular schwannoma (ICVS) and to analyze the relationship between tumor volume and ADC (apparent diffusion coefficient) and FA (fractional anisotropy) values.MethodSeventeen patients with ICVS were evaluated before and after GKR. ADC and FA values of the lateral lemniscus (LL) and inferior colliculus (IC) and tumor volume were calculated. Patients who responded to GKR were classified as Group 1 and those who did not respond adequately as Group 2. The relationship between ADC and FA values and changes in tumor volume were analyzed.ResultsTumor volume significantly decreased after GKR. ADC values obtained from the tumor increased after GKR (p:0.002). There was no significant difference in LL and IC before and after GKR in terms of FA and ADC values (n:17). There was a positive correlation between response to treatment and contralateral LL ADC values after GKR (p=0.005, r:0.652). There was a negative correlation between contralateral IC FA values after GKR and response to treatment (p=0.017, r: -0.568). There was a significant difference between Groups 1 and 2 in regards to contralateral LL ADC (p=0.03) and IC FA values (p=0.017).ConclusionSince the cochlear nerve and subcortical auditory pathways have low regeneration potential after nerve damage, ADC and FA changes in LL and IC may be explained with the presence of intracanalicular tumors prior to GKR. Since GKR does not cause additional damage to the subcortical auditory pathways at the brainstem level, we think that GKR is a noninvasive treatment method that can be used safely in patients with ICVS.