Koos Classification Research Articles

Delayed facial nerve palsy after vestibular schwannoma resection: risk factors, extent and prognosis.

Facial nerve palsies may develop during the postoperative period of microsurgical removal of vestibular schwannomas (VSs), even after normal facial function for days or weeks after surgery. The aim of this study was to identify the pathomechanism and predictive factors of delayed palsy. The clinical data of 193 patients who underwent vestibular schwannoma surgery between 2012 and 2021 were retrospectively analyzed. A total of 134 patients were included. The patients showed intact facial nerve function up to 24h after surgery. All patients (n = 20) with palsy from postoperative day 4 were included and collectively referred to as delayed facial nerve palsy (DFNP). Various factors were checked using a binomial regression analysis. The mean age of patients with DFNP was 57.8 years (55% female, 45% male). 70% had VS with KOOS ≥ 3, and 60% underwent surgery via a translabyrinthine approach Among the 16 patients with DFNP-related neurotropic pathogens, 25% were seropositive for herpes simplex virus. Most patients (n = 9/20) experienced onset of palsy between postoperative days 6 and 10. Of the four variables included in the significance test, three were significant: KOOS ≥ 3 (p < .04), ipsilateral vestibular organ failure (p < .05), and age group (p < .03). After therapy, 100% of patients recovered almost complete facial nerve function. The parameters mentioned above (KOOS classification and ipsilateral vestibular dysfunction) could be proven risk factors for the occurrence of DFNP.

Gustatory Function in Patients With Cerebellopontine Angle Masses.

To investigate the impact of cerebellopontine angle (CPA) masses on subjective and measured taste function. Retrospective cross-sectional study. Tertiary referral center. Consecutive adult patients with untreated CPA masses. Gustatory function was psychophysically measured with Taste Strips (range, 0-16) on both sides of the tongue. Subjective taste complaints were assessed using a questionnaire. Half-sided taste impairment (hemi-ageusia) was defined as side-to-side asymmetry ≥4 points with <9 points on the side of the CPA mass. We used the Koos classification for vestibular schwannomas (VS) and, in the case of facial nerve palsy, the House-Brackmann grading system. We included 135 patients (mean [standard deviation (SD)] age, 55.3 ± 14.1 yr; 62 males). The most common CPA mass was VS (77%). Overall, the measured taste function was lower on the affected compared with the healthy side of the tongue (mean score, 9.8 ± 3.3 versus 11 ± 2.9; p < 0.0001). Looking for clinically relevant one-sided taste impairment revealed 18 (13.3%) patients with hemi-ageusia, but only 4 (30.8%) of those subjectively complained of taste dysfunction. Regarding VS, Koos IV masses presented the lowest score on the affected side (mean score, 7.5 ± 3.7). Six patients presented with facial palsy. Having facial palsy did not result in a lower Taste Strips score (p = 0.23). Before any CPA mass treatment, a measurable ipsilateral decrease in gustatory function is present in many patients. Most patients do not notice this preexisting taste impairment. From a medicolegal standpoint, this warrants consideration. To avoid postoperative claims regarding taste function, a preoperative assessment may be considered.

Comparative Analysis on Vestibular Schwannoma Surgery with and without Intraoperative Fluorescein Sodium Enhancement

Background: Vestibular schwannoma (VS), also known as acoustic neuroma, is a benign, well-encapsulated, and slow-growing tumor that originates from Schwann cells, which form the myelin sheath around the vestibulocochlear nerve (VIII cranial nerve). The surgical treatment of this condition presents a challenging task for surgeons, as the tumor’s location and size make it difficult to remove without causing damage to the surrounding structures. In recent years, fluorescein sodium (FS) has been proposed as a tool to enhance surgical outcomes in VS surgery. This essay will provide an analytical comparison of the use of FS in VS surgery, evaluating its benefits and limitations and comparing surgical outcomes with and without FS-assisted surgery. Methods: In a retrospective study conducted at San Filippo Neri Hospital, we examined VS cases that were operated on between January 2017 and December 2023. The patients were divided into two groups: group A, which consisted of patients who underwent surgery without the use of FS until January 2020 (102 cases), and group B, which included patients who underwent surgery with FS after January 2020 (55 cases). All operations were performed using the retrosigmoid approach, and tumor size was classified according to the Koos, et al. classification system. The extent of surgical removal was evaluated using both the intraoperative surgeon’s opinion and postoperative MRI imaging. Preoperatively and postoperatively, facial nerve function and hearing were assessed. In group B, FS was used to assist the surgical procedures, which were performed using a surgical microscope equipped with an integrated fluorescein filter. Postoperative clinical and MRI controls were performed at six months and annually, with no patients lost to follow-up. Results: This study investigated the impact of intraoperative fluorescein exposure on tumor resection and clinical outcomes in patients with VS. The study found a statistically significant difference in the tumor resection rates between patients who received fluorescein intraoperatively (p = 0.037). Further analyses using the Koos classification system revealed a significant effect of fluorescein exposure, particularly in the Koos 3 subgroup (p = 0.001). Notably, no significant differences were observed in hearing loss or facial nerve function between the two groups. A Spearman correlation analysis revealed a positive correlation between tumor size and Koos, age, and size, but no significant correlation was found between facial nerve function tests. Conclusions: FS-assisted surgery for VS may potentially enhance tumor resection, allowing for more comprehensive tumor removal.

Translabyrinthine approach in acoustic neuroma surgery – case report

Introduction. Acoustic neuroma is a benign tumor that arises from the glial Schwann sheath junction of the vestibulocochlear nerve. It has an incidence of 1:100000 population. Despite the fact that this is a rare tumor, it accounts for approximately 6% of all intracranial tumors and 80% of tumors localized in cerebellopontine angle. Treatment of acoustic neuroma is represented by “Wait and Scan” monitoring, radiologic and surgical treatment. The latter remains the primary treatment for acoustic neuroma and consists of 3 main approaches: retrosigmoid approach, middle cranial fossa approach and translabyrinthine approach. Until now, in our country, acoustic neuroma surgery was done only by retrosigmoid approach. Case presentation. The first translabirinthine surgery for acoustic neuroma in our country was done on 09.12.2021 on a 60-year-old patient who, during preparation for cochlear implant surgery, was accidentally diagnosed with 3rd grade right acoustic neuroma, according to Koos classification. Patient had cophosis on the right ear and moderate hearing loss in the left ear. During the surgery, a gross total resection of the tumor was accomplished. The patient was discharged from the medical institution on 20.12.2021 in a satisfactory condition. Magnetic resonance imaging performed 3 months and 1 year after the surgery showed no complications or tumor remnants. Conclusion. The current report, which describes an accidental diagnosis of acoustic neuroma during preparation for a cochlear implantation surgery, resulted in acoustic neuroma surgery through the translabyrinthine approach. This serves as an eloquent example of why it is necessary to perform initially a magnetic resonance examination in cases of sensorineural hearing loss or tinnitus. The translabyrinthine approach in acoustic neuroma surgery allows for the removal of tumors of any size without affecting the brain, especially the cerebellum. In our case, where the patient had cophosis on the side of the tumor, this was the most appropriate surgical approach.

Case report: Cystic vestibular schwannoma

Background: Cerebellopontine angle tumors are a severe condition because of their life-threatening and functional loss potential, explained by the narrowness of the posterior fossa. The vestibular schwannoma, or acoustic neuroma, is a benign, well-circumscribed extraaxial tumor that arises from Schwann cells of the vestibulocochlear cranial nerve. The tumor is usually mainly solid, but can sometimes develop small cystic areas, due to degenerative modifications, causing microcyst formation. The coalescent of small cysts leading to forming a larger one, and responsible of a predominant cystic contingent, is rare, which makes interesting the case we are about to present. Case report: We are about to report the case of a 64-year-old male patient, with no particular medical history, which clinical interview has noted only tinnitus as a present symptom. He had experienced one year ago several disequilibrium and dizziness episodes, who have subsequently stopped over time, without any particular treatment. He also felt a little loss of hearing, especially in the left ear, but thought it was probably age related. No clinical abnormality including the facial nerve palsy was found. The MRI showed a stage 4 (Koos classification) left cystic vestibular schwannoma. This lesion was compressing the left vertebral and basilar arteries, the brain stream, the left cerebellar hemisphere, the left middle cerebellar peduncle, and the fourth ventricle, causing a triventricular hydrocephalus. After reviewing all potential therapeutic options, the patient declined surgery and decided to postpone the treatment. Conclusion: MRI is definitely the best way to explore the posterior fossa, especially the cerebellopontine angle, and helps us differentiate between all numerous tumors than can develop in this space.

High-throughput RNA sequencing identifies the miRNA expression profile, target genes, and molecular pathways contributing to growth of sporadic vestibular schwannomas.

To assess the differences in the miRNA expression profile between small (stage I Koos classification) and large solid vestibular schwannoma (VS) tumors, using the RNA-seq technique. Twenty tumor samples (10 small and 10 large tumors) were collected from patients operated for VS in a Tertiary Academic Center. Tumor miRNA expression was analyzed using high-throughput RNA sequencing (RNA-seq) technique, with NovaSeq 6000 Illumina system. Bioinformatics analysis was done using statistical software R. Gene enrichment and functional analysis was performed using miRTargetLink 2.0 and DIANA miRpath 3.0 online tools. We identified 9 differentially expressed miRNAs in large VS samples: miR-7, miR-142 (-3p and -5p), miR-155, miR-342, miR-1269, miR-4664, and miR-6503 were upregulated, whereas miR-204 was significantly down-regulated in comparison to small VS samples. Gene enrichment analysis showed that the most enriched target genes were SCD, TMEM43, LMNB2, JARID2, and CCND1. The most enriched functional pathways were associated with lipid metabolism, along with signaling pathways such as Hippo and FOXO signaling pathway. We identified a set of 9 miRNAs that are significantly deregulated in large VS in comparison to small, intracanalicular tumors. The functional enrichment analysis of these miRNAs suggests novel mechanisms, such as that lipid metabolism, as well as Hippo and FOxO signaling pathways that may play an important role in VS growth regulation.

P11.38.A CYSTIC VESTIBULAR SCHWANNOMA - A SUBGROUP ANALYSIS FROM A COMPARATIVE STUDY BETWEEN RADIOSURGERY AND MICROSURGERY

Abstract BACKGROUND Some vestibular schwannoma (VS), show cystic morphology. It is known that these cystic vestibular schwannomas (cVS) bear different surgical risk profile compared to non-cystic VS (ncVS) in surgical treatment. This study aims to analyze the management of cVS compared to ncVS in a dual center study of surgically (SURG) and radiosurgically (SRS) treated VS patients. MATERIAL AND METHODS This is a retrospective multi-center cohort study. Data was retrospectively collected from two large centers involved in the treatment of vestibular schwannomas for patients between 2005 und 2011 to enable long-term follow-up (FU). Tumor size was classified by Koos Classification. Previously treated VS and VS associated with Neurofibromatosis were excluded. Clinical state was reported by House and Brackmann (H&amp;B) and Gardner-Robertson (G&amp;R) scale (with H&amp;B and G&amp;R 1-2 considered as good outcome), and Recurrence-free-survival (RFS) was assessed radiographically by contrast-enhanced MR imaging. Data on VS-associated symptoms like trigeminal affection, tinnitus, and vertigo/imbalance were also collected. RESULTS The study population included N=901 patients, who were treated in both centers. N=559 (62%) patients were treated by SRS, and N=342 (38%) patients by SURGERY. N=55 (6%) of all patients showed cystic MR-morphology. These were more often treated by SURG (N=31/55, 58%) compared to ncVS (N=311/845, 37%) (p=0.002). Patients with cVS were indifferent in mean age compared to ncVS. The rate of women was higher in cVS (64%), compared to ncVS (55%) (p=0.001). The overall incidence of recurrence was 16% in cVS (8% in ncVS). Tumor control was worse in cVS treated by SRS (N=6/24, 25%) compared to SURGERY (N=3/32, 9%). When surgically treated, gross total resection (GTR) was achieved in 87% in cVS, whereas this rate was higher in non-cystic VS at 96% (p=0.001). The number of patients N=5/32 (16%) with postoperative relevant facial palsy (HB&amp;gt;2) was significantly higher in cVS (ncVS: N=28/310; 9%). CONCLUSION Tumor control in cVS is significantly worse in SRS compared to SURG and SRS-treated ncVS. However, when cVS is treated surgically, the rate of GTR is lower and the number of patients with relevant postoperative facial palsy higher compared to ncVS. Cystic morphology in VS poses a challenge in management (both SRS and SURG) compared to non-cystic tumors. Treatmend decision and patients' consultation should contemplate and address negative prognostic factor of cystic morphology in VS.

P11.73.B COMPARING GAMMA KNIFE RADIOSURGERY WITH MICROSURGERY AND THEIR RISK-BENEFIT-RATIO OF TUMOR CONTROL AND FACIAL DETERIORATION IN LARGE VESTIBULAR SCHWANNOMAS (KOOS III-IV)

Abstract BACKGROUND The level of evidence to provide treatment recommendations for vestibular schwannoma (VS) is low. Both stereotactic radiosurgery (SRS) and microsurgical resection (SURGERY) are available as treatment options for VS. If treated with monotherapy alone, SRS has shown to be inferior in tumor control, but superior in facial nerve preservation compared to SURGERY. The aim of this study was to analyze the risk-benefit-ratio in the treatment of large VS (Koos III-IV) comparing SRS and SURGERY. MATERIAL AND METHODS This is a retrospective dual-center cohort study enrolling consecutive patients with solitaryVS between 2005 und 2011 to enable follow-up of up to 10 years. Tumor size was classified by Koos Classification. Clinical state was reported by House and Brackmann (H&amp;B) and Gardner-Robertson (G&amp;R) scale (with H&amp;B and G&amp;R 1-2 considered as good outcome), and Recurrence-free-survival (RFS) was assessed radiographically by contrast-enhanced MR imaging. As an expression of success/harm, the absolute risk reduction (ARR) and risk increase (ARI) were calculated as the difference between incidence of recurrences and facial deterioration rates in patients treated with SRS and SURGERY, respectively. ARR and ARI were used to derive additional estimates of treatment effectiveness (in SURGERY), i.e. the number-to-operate (NNO) and the number-to-harm (NNH), respectively. RESULTS The study population included N=901 patients, who were treated in both centers. N=492 (55%) were large VS (Koos III-IV). Of them N=260 (53%) were treated with SRS and N=232 (47%) with SURG. The SRS treatment arm presented with a recurrence rate of 14.2%, and SURGERY with 3.0%. Therefore, ARR for recurrence was 11.21% (95% CI: 6.4%-16.0%) with a NNO of 9 (95% CI: 6.3-15.6) in SURGERY meaning that one in every 9 patients will benefit from SURGERY treatment. When analyzing facial nerve deterioration (facial paresis HB&amp;gt;2 and facial spasm) in large VS, SRS presented with 6.9%, and SURGERY with 12.5% adverse facial nerve outcome resulting in an ARI of 5.6% (95%CI: 0.3%-10.8%) and a NNH of 18 (95%CI:9.2-312.1). CONCLUSION The analysis of the different proportion in success/harm in the management of large VS (SRS vs. SURGERY) in this cohort yielded in a low NNO, combined with a high NNH. This shows that SURGERY was superior to SRS considering tumor control in large VS (Koos III-IV). Still, the direct translation of these results into treatment recommendations is not self-evident, but multi-faceted: This analysis is a vivid representation of a dilemma well-known to neuro-oncological surgeons - the negotiation between tumor control and functional outcome. Large VS should be treated in specialized centers, which have enough experience to ensure a high-rate of facial preservation in large VS (Koos III-IV).

P11.62.A GENDER-RELATED DIFFERENCES IN PATIENTS CHARACTERISTICS, AND TREATMENT OUTCOME IN A COMPARATIVE STUDY OF MICROSURGERY AND RADIOSURGERY OF VESTIBULAR SCHWANNOMA

Abstract BACKGROUND Gender-related differences in patients with sporadic, unilateral vestibular schwannoma (VS) are poorly investigated so far. In studies focusing on natural history, tumor growth was described to be indifferent in either sex. However, it remains unclear whether patient’s sex affects the treatment response to stereotactic radiosurgery (SRS) or microsurgical resection (SURGERY). This study elucidates sex-related differences in VS care. MATERIAL AND METHODS This is a retrospective multi-center cohort study. Data was retrospectively collected from two large centers involved in the treatment of vestibular schwannomas for patients between 2005 und 2011 to enable long-term follow-up (FU). Tumor size was classified by Koos Classification. Previously treated VS and patients with Neurofibromatosis were excluded. Clinical state was reported by House and Brackmann (H&amp;B) and Gardner-Robertson (G&amp;R) scale (with H&amp;B&amp;lt;3 and G&amp;R 1-2 considered as good outcome), and Recurrence-free-survival (RFS) was assessed radiographically by contrast-enhanced MR imaging. Data on VS-associated symptoms like trigeminal affection, tinnitus, and vertigo/imbalance were also collected. RESULTS The study population included N=901 patients, who were treated in both centers. N=502 (56%) VS patients were female and N=399 (44%) were male. At time of treatment, women (56 years SD±13.50) were significantly older in age then men (53 years SD±13.80) (p=0.001). Tumor size, cystic morphology, intracanalicular extension, provided care (SRS, SURGERY), treatment related complications, and extent of surgical resection were insignificant in both gender-groups. The incidence of relevant preoperative vertigo was higher in women (67%) then in men (55%) (p=0.002). Pre- and postoperative facial function, hearing loss, and trigeminal symptoms were similar in both groups. Overall incidence of recurrence was insignificant (p=0.106). However, the in subgroups, tumor control with SRS was significantly worse in women compared to men (p=0.035). CONCLUSION Provided Care, functional outcome and peri-interventional morbidity were the same in either sex. Relevant vertigo was significantly more often present in women. The incidence of recurrence is higher in women with VS, when treated with SRS compared to men, although tumor characteristics were similar. Additional research is needed to elucidate gender-related difference in tumor biology affecting the response to VS treatment.

P11.36.A TUMOR CONTROL AND FUNCTIONAL OUTCOME IN VESTIBULAR SCHWANNOMA - RESULTS FROM A DUAL-CENTER STUDY COMPARING MICROSURGERY AND GAMMA KNIFE RADIOSURGERY

Abstract BACKGROUND The level of evidence to provide treatment recommendations for vestibular schwannoma (VS) is low. Both Stereotactic Radiosurgery (SRS) and microsurgical resection (SURG) are available as treatment options for VS. There are very few direct comparative studies comparing both treatment modalities in large cohorts allowing detailed subgroup analysis. MATERIAL AND METHODS This is a retrospective dual-center cohort study. Data was retrospectively collected from two large centers involved in the treatment of solitary vestibular schwannomas for patients between 2005 und 2011 to enable follow-up of up to 10 years. Tumor size was classified by Koos Classification. Clinical state was reported by House and Brackmann (H&amp;B) and Gardner-Robertson (G&amp;R) scale (with H&amp;B and G&amp;R 1-2 considered as good outcome), and Recurrence-free-survival (RFS) was assessed radiographically by contrast-enhanced MR imaging. VS-associated symptoms like trigeminal affection, tinnitus, and vertigo/imbalance were also collected. RESULTS The study population included N=901 patients, who were treated in both centers. N=559 patients were treated by SRS, and 342 patients by SURG.Treatment-related functional deterioration (e.g. hearing and facial deterioration) was significantly more common in patients treated by SURG. The incidence of complications was similar in both groups (14% and 13%). Secondary VS-related symptoms like tinnitus, vertigo, imbalance and trigeminal symptoms were significantly improved by microsurgery, but not by SRS. This study reported an overall incidence of recurrence in SURG of only 4%, and 11% in SRS respectively. Tumor control was comparable in small tumors (Koos I and II) in both SRS and SURG. Patients treated by SRS had significantly smaller tumors (p&amp;lt;0.001). In large VS (Koos III and IV), SURG is superior to SRS considering tumor control with a risk reduction for incidence of recurrence. CONCLUSION SRS can achieve similar tumor control compared to SURG in smaller VS (Koos I-II) - with less severe postinterventional morbidities (hearing and facial function loss). In large VS (Koos III-IV), tumor control by SRS is inferior to SURG. Therefore, while SURG is increasing the risk for facial palsy, it reduces the risk for recurrence. Moreover, SURG may improve secondary VS symptoms (e.g. tinnitus, vertigo/imbalance and trigeminal symptoms), even in small VS. Our data on tumor control and tumor size in SRS and SURG suggest that if combination therapy is chosen, the residual tumor for adjuvant SRS should not exceed the size of Koos II.These figures should be considered when deciding on treatment modality.

Subclassification of the Koos grade 2 vestibular schwannoma into 2a and 2b for individualized patient care: A validity and reliability study

ObjectiveVestibular schwannoma (VS) growth of ≥2 mm during serial MRI observation, irrespective of size, is the benchmark for treatment initiation in almost all centers. Although the probability of less optimal outcomes significantly increases in VS closer to the brainstem, early intervention does not improve long-term quality of life. Moving beyond the recommendation of definitive treatment for all VS after detected growth, we subclassified Koos 2 tumors based on extrameatal extension and relation to the brainstem. The aim of the current study was to evaluate the Koos 2 subclassification’s validity and the inter-and intra-rater reliability of the entire Koos classification. MethodsSix experts, including neurosurgeons, otorhinolaryngologists and radiologists from two tertiary referral centers, classified 43 VS MRI scans. Validity of the Koos 2 subclassification was evaluated by the percentage agreement against the multidisciplinary skull base tumor board management advice. Inter- and intra-rater reliability were calculated using the intraclass correlation coefficient (ICC). ResultsValidity was almost perfect in Koos 2a VSs with a 100% agreement and 87.5% agreement for Koos 2b. Inter-rater reliability for all Koos grades was significantly excellent (ICC 0.91; 95%CI 0.866 to 0.944, p= <0.001). Five raters had an excellent intra-rater reliability (ICC > 0.90; p= <0.01) and one rater had a good intra-rater reliability (ICC 0.88; 95% CI 0.742 to 0.949). ConclusionsAlthough multiple factors influence decision-making, the classification of Koos 2a and 2b with excellent inter- and intra-rater reliability, can aid in recommending treatment initiation, moving beyond detected tumor growth, aiming to optimize patient centered care.

Subjective perception of activity level: A prognostic factor for developing chronic dizziness after vestibular schwannoma resection?

IntroductionA vestibular schwannoma (VS) resection causes an acute unilateral vestibular deafferentation resulting in acute postoperative symptoms. Despite the expected resolution of most of the symptoms, due to central vestibular compensation, more than one out of four patients develop chronic dizziness. Several predictive factors, such as age and tumor size, have been suggested. Despite its potential effect on the process of central vestibular compensation, the level of physical activity after VS resection was not yet considered. Therefore, the association between the level of physical activity and chronic dizziness after VS resection will be investigated.MethodsThis retrospective cohort study included 66 patients who underwent a retro-sigmoid VS resection between October 2001 and February 2007. Patients were assessed before surgery and at 9 weeks and 6 months postoperatively. At 9 weeks, patients were asked to report their level of physical activity (PA) during the past week by using a visual analogue scale and their balance performance was assessed by four standing balance conditions with eyes closed and the Timed Up and Go test (TUG). Based on the Dizziness Handicap Inventory (DHI) score at 6 months, patients were divided in a chronic dizziness group (DHI > 30) and non-chronic dizziness group (DHI-score ≤ 30). Age, sex, Koos classification, preoperative vestibular function, treatment group, balance performance, and level of PA were compared between both groups and used as independent variables in linear regression analyses with the DHI score at 6 months as dependent variable.ResultsThe chronic dizzy patients revealed to have significantly lower levels of PA (p < 0.001) and worse static and dynamic balance performance (p = 0.023 and p = 0.041, respectively) 9 weeks after surgery. After elimination, the multiple regression analysis resulted in a model with two variables (PA level, TUG) which significantly predicted the DHI score (F2,42 = 6.581; R2 = 0.239; p = 0.003).ConclusionThis study revealed associations between (1) the level of PA and balance performance in the subacute phase and (2) chronic dizziness after VS resection. Assessment of the level of PA and balance performance during the subacute phase, which can be performed in a non-invasive and non-time-consuming way, might therefore provide prognostic information after VS resection.

Impact of Demographics and Clinical Features on Initial Treatment Pathway for Vestibular Schwannoma.

To identify demographic and clinical features impacting initial treatment pathway for vestibular schwannoma. Retrospective chart review. Tertiary care academic medical center. Patients diagnosed with vestibular schwannoma between 2009 and 2019. Observation, stereotactic radiosurgery, or microsurgical resection. χ 2 Test, one-way analysis of variance, and multivariate logistic regression were used to correlate demographic and clinical factors with initial treatment pathway for 197 newly diagnosed vestibular schwannoma patients. Among 197 patients, 93 (47%) were initially treated with observation, 60 (30%) with stereotactic radiation (Gamma Knife) and 44 (22%) with surgical resection. Age univariately had no statistically significant impact on initial pathway, but those undergoing surgery trended toward a younger demographic (49.1 yr [surgery] versus 57.2 yr [observation] versus 59.0 yr [Gamma Knife]). Men were more likely to be initially observed than women ( p = 0.04). Patients initially observed were more likely to have a lower Koos classification ( p < 0.001) and have better tumor-ear hearing ( p = 0.03). Only 34.4% of patients living outside the local geographic region were initially observed compared with 53.0% living locally ( p = 0.055). Surgeon correlated with initial treatment ( p = 0.04) but did not maintain significance when adjusting for hearing level or tumor size. A multiple linear regression model found age, maximum tumor diameter, and Koos class to correlate with initial treatment pathway ( p < 0.0001, r2 = 0.42). Initial treatment pathway for newly diagnosed vestibular schwannoma is impacted by demographic factors such as age, sex, and geographic proximity to the medical center. Clinical features including hearing level and tumor size also correlated with initial treatment modality.

Could the Audiometric Criteria for Sudden Sensorineural Hearing Loss Miss Vestibular Schwannomas?

To investigate the likelihood of missing a vestibular schwannoma (VS) diagnosis in patients who present with a sudden hearing loss (SHL) that does not meet the most accepted audiometric criteria for sudden sensorineural hearing loss (SSNHL) (a decrease of ≥30 dB at three consecutive frequencies). All adult patients (>18 years) diagnosed with SHL of any severity in a tertiary care referral medical center between 2015 and 2020 and who underwent an MRI scan to rule out VS were included. Statistical analyses were conducted to evaluate the difference between the rate of VS among patients with an initial audiogram, which met the abovementioned criteria, and those who did not. Other audiometric criteria for SNHL were also evaluated (≥10 dB at ≥2 frequencies and ≥ 15 dB at one frequency). Of the 332 patients included in the study, 152 met the audiometric criteria for SSNHL, and 180 did not. Both groups had a similar VS rate (8.6% vs. 8.9%, p=0.914). Similar results were found when other audiometric criteria for asymmetric SNHL were analyzed. In a subgroup analysis of patients with VS-associated SSNHL, neither the tumor size nor the Koos classification was associated with any of the audiometric criteria systems. There should be a high index of suspicion for the presence of VS in patients with an SHL of any severity. 3 Laryngoscope, 133:670-675, 2023.

Automated Koos Classification of Vestibular Schwannoma.

The Koos grading scale is a frequently used classification system for vestibular schwannoma (VS) that accounts for extrameatal tumor dimension and compression of the brain stem. We propose an artificial intelligence (AI) pipeline to fully automate the segmentation and Koos classification of VS from MRI to improve clinical workflow and facilitate patient management. We propose a method for Koos classification that does not only rely on available images but also on automatically generated segmentations. Artificial neural networks were trained and tested based on manual tumor segmentations and ground truth Koos grades of contrast-enhanced T1-weighted (ceT1) and high-resolution T2-weighted (hrT2) MR images from subjects with a single sporadic VS, acquired on a single scanner and with a standardized protocol. The first stage of the pipeline comprises a convolutional neural network (CNN) which can segment the VS and 7 adjacent structures. For the second stage, we propose two complementary approaches that are combined in an ensemble. The first approach applies a second CNN to the segmentation output to predict the Koos grade, the other approach extracts handcrafted features which are passed to a Random Forest classifier. The pipeline results were compared to those achieved by two neurosurgeons. Eligible patients (n = 308) were pseudo-randomly split into 5 groups to evaluate the model performance with 5-fold cross-validation. The weighted macro-averaged mean absolute error (MA-MAE), weighted macro-averaged F1 score (F1), and accuracy score of the ensemble model were assessed on the testing sets as follows: MA-MAE = 0.11 ± 0.05, F1 = 89.3 ± 3.0%, accuracy = 89.3 ± 2.9%, which was comparable to the average performance of two neurosurgeons: MA-MAE = 0.11 ± 0.08, F1 = 89.1 ± 5.2, accuracy = 88.6 ± 5.8%. Inter-rater reliability was assessed by calculating Fleiss' generalized kappa (k = 0.68) based on all 308 cases, and intra-rater reliabilities of annotator 1 (k = 0.95) and annotator 2 (k = 0.82) were calculated according to the weighted kappa metric with quadratic (Fleiss-Cohen) weights based on 15 randomly selected cases. We developed the first AI framework to automatically classify VS according to the Koos scale. The excellent results show that the accuracy of the framework is comparable to that of neurosurgeons and may therefore facilitate management of patients with VS. The models, code, and ground truth Koos grades for a subset of publicly available images (n = 188) will be released upon publication.

Vestibüler Şıvannomlarda Koos Sınıflaması ile ADC- Post Kontrast Sinyal İntensite Değerlerinin İlişkisi

Aim: To determine the interobserver reliability of the Koos classification which is used for grading vestibular schwannomas and to evaluate its correlation with Apperent Diffusion Coefficiency (ADC) and post contrast signal intensity values.&#x0D; Methods: Vestibular schwannomas were retrospectively scanned from picture archiving and communication system over a 4-year period. Koos grade of tumor was assessed by two radiologists blinded to the clinical and pathological data. Cohen’s Kappa was used to analyse interobserver agreement of Koos grade. The correlation between ADC, signal intensity measurements and Koos grade of tumors was analysed with Kendall’s tau b correlation coefficient.&#x0D; Results: 33 patients (21 females, mean age 52.6±16.6 years) with 34 vestibular schwannomas were included the study. The reliability analyses revealed excellent inter-observer agreement for ADC (ICC: 0.93, 95% CI: 0.87-0.97, p

Decision making on vestibular schwannoma treatment: predictions based on machine-learning analysis

Decision making on the treatment of vestibular schwannoma (VS) is mainly based on the symptoms, tumor size, patient’s preference, and experience of the medical team. Here we provide objective tools to support the decision process by answering two questions: can a single checkup predict the need of active treatment?, and which attributes of VS development are important in decision making on active treatment? Using a machine-learning analysis of medical records of 93 patients, the objectives were addressed using two classification tasks: a time-independent case-based reasoning (CBR), where each medical record was treated as independent, and a personalized dynamic analysis (PDA), during which we analyzed the individual development of each patient’s state in time. Using the CBR method we found that Koos classification of tumor size, speech reception threshold, and pure tone audiometry, collectively predict the need for active treatment with approximately 90% accuracy; in the PDA task, only the increase of Koos classification and VS size were sufficient. Our results indicate that VS treatment may be reliably predicted using only a small set of basic parameters, even without the knowledge of individual development, which may help to simplify VS treatment strategies, reduce the number of examinations, and increase cause effectiveness.

The Validity of the Koos Classification System With Respect to Facial Nerve Function.

The Koos classification of vestibular schwannomas is designed to stratify tumors based on extrameatal extension and compression of the brainstem. Our prior study demonstrated excellent reliability. No study has yet assessed its validity. To present a retrospective study designed to assess the validity of the Koos grading system with respect to facial nerve function following treatment of 81 acoustic schwannomas. We collected data retrospectively from 81 patients with acoustic schwannomas of various Koos grades who were treated with microsurgical resection or stereotactic radiosurgery. House-Brackmann (HB) scores were used to assess facial nerve function and obtained at various time points following treatment. We generated Spearman's rho and Kendall's tau correlation coefficients along with a logistic regression curve. We found no significant difference in the presence or absence of facial dysfunction by Koos classification when looking at all patients. There was a positive but fairly weak correlation between HB score and Koos classification, which was only significant at the first postoperative clinic appointment. There was a statistically significant difference in the presence or absence of facial dysfunction between patients treated with surgery vs radiation, which we expected. We found no statistically significant difference when comparing surgical approaches. Logistic regression modeling demonstrated a poor ability of the Koos grading system to predict facial nerve dysfunction following treatment. The Koos grading system did not predict the presence of absence of facial nerve dysfunction in our study population. There were trends within subgroups that require further exploration.

THE RESULTS OF SURGICAL TREATMENT OF ACOUSTIC NEUROMA BY DRILLING THE POSTERIOR WALL OF THE INTERNAL AUDITORY CANAL VIA THE RETROSIGMOID SUBOCCIPITAL APPROACH

Objective: To assess of surgical results of acoustic neuroma by the retrosigmoid suboccipial approach with drilling the posterior wall of the internal auditory canal. Patients and methods: A prospective study with 26 patients who were diagnosed with acoustic neuroma and surgically treated by drilling the posterior wall of the internal auditory canal via retrosigmoid suboccipital approach at Viet-Duc Hospital from January 2019 to October 2020. Results: Mean age: 42.74±14.95; male: female ratio was 1; tinnitus was the most common symptom (76.92%), after that hearing loss (69.23%). There was no predominant in the side of the tumor. There was a significant difference between KOOS classification’s tumor before and after surgery, as well as the facial nerve function 3-month post-operation versus discharge time. Conclusion: The retrosigmoid suboccipital approach with drilling the posterior wall of the internal auditory canal was useful for treating acoustic neuroma both the tumor removing capacity and facial nerve preservation.

Koos Classification of Vestibular Schwannomas: A Reliability Study.

The Koos classification of vestibular schwannomas is designed to stratify tumors based on extrameatal extension and compression of the brainstem. While this classification system is widely reported in the literature, to date no study has assessed its reliability. To assess the intra- and inter-rater reliability of the Koos classification system. After institutional review board approval was obtained, a cross-sectional group of the Magnetic Resonance imagings of 40 patients with vestibular schwannomas varying in size comprised the study sample. Four raters were selected to assign a Koos grade to 50 total scans. Inter- and intrarater reliability were calculated and reported using Fleiss' kappa, Kendall's W, and Intraclass correlation coefficient (ICC). Inter-rater reliability was found to be substantial when measured using Fleiss' kappa (.71), extremely strong using Kendall's W (.92), and excellent as calculated by ICC (.88).Intrarater reliability was perfect for 3 out of 4 raters as assessed using weighted kappa, Kendall's W and ICC, with the intrarater agreement for the fourth rater measured as extremely high. We have demonstrated that the Koos classification system for vestibular schwannoma is a reliable method for tumor classification. This study lends further support to the results of current literature using Koos grading system. Further studies are required to evaluate its validity and utility in counseling patients with regard to outcomes.