Giant Vestibular Schwannomas Research Articles

Optimizing retrosigmoid approach for giant vestibular schwannoma resection: strategies and advances in surgical technique

Optimizing retrosigmoid approach for giant vestibular schwannoma resection: strategies and advances in surgical technique

Peculiarities of cerebral blood flow and vascular reactivity in patients with large and giant tumors of the cerebello-pontine angle

Background. Vestibular schwannomas and posterior fossa meningiomas are one of the most difficult tumors for surgical treatment. The mortality rate after their removal reaches 13,5 %. The main causes of death are hemorrhagic and ischemic complications. There are no studies in the literature on tissue perfusion of brainstem structures and cerebellum and reactivity of vertebral and basilar arteries in patients with extraaxial tumors of the posterior cranial fossa. Therefore, the study of the blood supply of the brainstem structures and cerebellum, as well as the functional characteristics of the vertebral and basilar arteries in these patients is of considerable interest.Aim. To evaluate tissue perfusion of the pons and cerebellum, as well asthe reactivity of the vertebral and basilar arteries in patients with large and giant vestibular schwannomas and posterior fossa meningiomas.Materials and methods. Eighty-two patients with large and giant extraaxial tumors of the base of the posterior cranial fossa were examined. The median age was 54 [44; 61] years. Vestibular schwannomas were diagnosed in 52.4 % of patients, and meningiomas of the posterior cranial fossa were diagnosed in 47.6 %. All patients underwent duplex scanning of the basilar and vertebral arteries. We evaluated linear blood flow and coefficients of reactivity and index of vasomotor reactivity. We investigated the metabolic reactivity of cerebral blood flow by conducting hyper- and hypocapnic tests. Computed tomography perfusion imaging was performed in 18 patients. We detected cerebral blood volume, cerebral blood flow, mean transit time of contrast agent and time to peak of contrast agent. Measurements were carried out in six regions of interest located symmetrically on the pons and in the white matter of the cerebellar hemispheres on the side of the tumor and on the opposite side.Results. Linear blood flow rates in the intracranial segments of the vertebral and the basilar arteries in patients with tumors were higher than in the comparison group (p<0.05). These patients are characterized by a decrease of reactivity coefficients in the vertebral and basilar arteries, especially when performing hypercapnic tests (p <0.05). Paradoxical reactivity and areactivity were diagnosed in 34.9 % of patients with vestibularschwannomas and 25.6 % with meningiomas. In the pons on the side of the tumor in patients with vestibularschwannomas, a decrease in cerebral blood flow by 19.3 %, an increase in cerebral blood volume by 33.3 % and an increase in mean transit time of contrast agent and in time to peak of contrast agent by 48.1 % and 71.1 % (p <0.05) were found. In patients with meningiomas in the pons on the side of the tumor, all perfusion parameters were higher (p<0.05). In the deep regions of the cerebellar hemisphere on the side of the tumor in patients with tumors, all perfusion parameters were higher compared to the opposite side.Conclusion. The results of the study made it possible to quantify cerebral blood flow in patients with large and giant vestibular schwannomas and meningiomas of the posterior cranial fossa base. The revealed changes indicate the risk of developing pathological vascular reactions and disorders of cerebral blood flow in the postoperative period.

ICU Management of Post-Craniotomy Patients with Schwannoma Vestibular Tumor Removal

Background: Vestibular schwannoma (VS) is a relatively common tumor that arises from the vestibulocochlear nerve (CN VIII) and represents 80% of cerebellopontine angle (CPA) masses. CPA tumors are mostly benign, slow growing with low malignant potential (~1%). VS have rarely been reported, and there is a lack of in-depth discussion on the experience of management of massive acoustic neuromas in ICU. It represents the case in which the patient presented with obstructive hydrocephalus and progressive neurological deficits. The purpose of this case report is to understand the management of post-operative patients with VS with several comorbidities in the ICU.Case: We present a 53 years old woman with a giant VS and obstructive hydrocephalus. An imaging findings revealed a brain tumor in the CPA region and obstructive hydrocephalus. Consequently, she relieved her hydrocephalus with a ventriculoperitoneal shunt (VP shunt). After 1.5 years, her mental condition deteriorated, and her left limb muscle strength gradually decreased. Under a joint consultation with Department of Neurosurgery and Anesthesiology, she underwent tumor removal. Upon discharge, the previously observed neurological deficits, which were reversible had been successfully resolved. The neuroimaging confirmed the complete tumor removal, while the neuropathologic examination revealed a VS.Discussion: If untreated, an acoustic neuroma can grow large enough to cause pressure on the brain stem. The tumor can block the flow of cerebrospinal fluid (CSF) between the brain and the spinal cord, causing a buildup of the fluid in the brain. Because the skull is a closed structure, excess fluid in the brain (hydrocephalus) can press against the brain, causing unsteady movement and lack of coordination (ataxia), headaches and confusion. Patients with brainstem compression had significantly longer mean LOS than patients without. Also, the dissection of the facial nerve from the tumor in order to preserve it can sometimes cause swelling, which can result in weakness or paralysis (complete or partial loss of muscle function). This is usually temporary but can take weeks to months to recover. After the operation, the patient was treated in the ICU, a ventilator was installed,insulin was given to regulate blood sugar and anti-hypertension medication for maintaining blood pressure. During treatment in the ICU, adequate fluids and nutrition are provided. Monitoring is carried out on cardiovascular function, hemodynamics and respiration by monitoring blood pressure, electrocardiogram (ECG), oxygen saturation. The patient was moved to high care unit (HCU) after being treated for 3 days in the ICU.Conclusion: Postoperative therapy is more focused on supportive therapy, including maintaining the airway, regulating blood sugar, blood pressure and providing mechanical ventilation to maintain adequate oxygenation.

Facial and Cochlear Nerves Outcomes in the Surgical Resection of Giant Vestibular Schwannoma: Is There Any Predictive Value for Intraoperative Neuromonitoring of the Facial Nerve?

Background: Giant vestibular schwannoma (VS) represents one of the most challenging interventions in skull base surgery. Preserving facial and cochlear nerves requires effective surgical planning and nuanced techniques. Objectives: The present study evaluates the role of intraoperative neuromonitoring (IONM) in predicting the outcome of facial and cochlear nerves. Methods: This retrospective cohort comprised 34 patients with a giant (Samii IV/IVb grade) VS during 2016 - 2019. The retrosigmoid approach was used for tumor resection. Pre- and postoperative facial exams were graded according to the House-Brackmann Scale. Hearing ability was also classified according to the Hannover Hearing Classification. Intraoperative findings included the location of the nerve complex, tumor consistency, the surgical plane of the tumor from the facial nerve/ brainstem, and the level of internal auditory canal (IAC) decompression. Intraoperative neuromonitoring was used for all surgeries. The amplitude required for a positive response was recorded during the facial nerve's direct electrical stimulation (DES). All patients were followed 6 and 12 months postoperative. Results: The preoperative facial nerve function was normal in 91.2% of patients, and 8.8% had slight facial nerve impairment (FNI). Considering preoperative hearing status, 9 cases (26.5%) had moderate hearing loss or impairment, while 25 patients (73.5%) complained of severe hearing impairment. The mean intraoperative direct facial nerve stimulation threshold was 1.38 ± 0.89. Hearing impairment was moderately severe in 7 (20.6%) and severe in 25 patients (73.5%) postoperation. In addition, postoperative assessment revealed 13 (38.2%) cases with moderate FNI and 12 (35.2%) with moderately severe FNI. The tumor size did not affect the postoperative hearing loss, and the postoperative hearing loss did not improve significantly (P = 0.32). There was no statistically significant correlation between the intensity of intraoperative DES and postoperative facial nerve function (P > 0.05). No significant correlation was observed between tumor consistency and postoperative hearing status (P > 0.05). Conclusions: The retrosigmoid approach combined with IONM appears to be associated with favorable facial and cochlear nerve outcomes in giant VS. The postoperative facial nerve function may improve, but sensorineural hearing status may not improve significantly. Moreover, the intensity of intraoperative DES may not predict the postoperative facial function. Therefore, the findings of IONM should be interpreted carefully.

Clinical outcomes and safety of large or giant vestibular schwannoma in older patients undergoing microsurgery: a matched cohort study.

To compare the clinical outcomes of large or giant vestibular schwannomas (VSs) between older patients and younger patients who underwent microsurgery and to explore whether the incidence of postoperative complications increased and whether the postoperative hospital stay was prolonged. We conducted a retrospective matched cohort study based on the surgical approach, maximum tumor diameter and extent of resection. Older patients (≥ 60 years) and a matched group (<60 years) who had undergone microsurgery for VSs between January 2015 and December 2021 were included. Clinical data, surgical outcomes and postoperative complications were analyzed statistically. Forty-two older patients (≥ 60 years, 66.0 ± 3.8 years) were identified and matched to younger patients (<60 years, 43.9 ± 11.2 years), and they all underwent microsurgery through a retrosigmoid approach. There were twenty-nine patients with 3-4cm VSs and thirteen patients with > 4cm VSs in both groups. The older patients had a higher proportion of imbalance (P = 0.016) and lower American Society of Anesthesiology scores (P = 0.003) before surgery than the younger patients. There was no significant difference in facial nerve function one week (p = 0.851) and one year (p = 0.756) after surgery and no difference in the postoperative complication incidence (40.5% vs. 23.8%, p = 0.102) between the older patients and controls. Furthermore, the older patients had longer postoperative hospital stays than the younger patients (p = 0.043). In the older group, six patients with near total resection and five with subtotal resection were administered stereotactic radiotherapy, and one had recurrence three years after surgery and received conservative treatment. The postoperative follow-up time ranged from 1 to 83 months, with an average of 33.5 ± 21.1 months. For older patients (≥ 60 years) with symptomatic, large or giant -VSs, microsurgery is the only effective method to prolong lifespan, alleviate clinical symptoms and cure the tumor. However, radical resection of VSs may result in a decreased preservation rate of facial-acoustic nerve function and an increased postoperative complication incidence. Therefore, subtotal resection followed by stereotactic radiotherapy should be recommended.

Hypo-fractionated Gamma Knife Radiosurgery for Intra-cranial Pathologies: A Single-Center Prospective Analysis of Feasibility, Safety, Efficacy, and Complication Profile.

Single-session stereotactic radiosurgery (SRS) is a proven and effective treatment modality for various benign, malignant, and functional intra-cranial pathologies. In certain situations, single-fraction SRS is limited because of lesion size and location. Hypo-fractionated gamma knife radiosurgery (hfGKRS) is an alternative approach for such unconventional indications. To evaluate the feasibility, efficacy, safety, and complication profile of hfGKRS with evaluation of different fractionation schemes and dosing patterns. The authors prospectively evaluated 202 patients treated with frame-based hfGKRS over a 9-year period. GKRS was administered fractionated because of either a large volume (>14 cc) or an inability to spare neighboring organs at risk from permissible radiation in single-session GKRS. The inter-fraction interval was kept at 24 hours, and the dose calculation was performed with linear quadratic equations. Patients with more than 3 years of clinical and radiological follow-up were included in prospective analysis. At pre-decided follow-up criteria, treatment effects and side effects were documented on objective scales. A total of 169/202 patients met inclusion criteria. 41% patients received treatment in three fractions, whereas 59% received two-fraction GKRS. Two patients of giant cavernous sinus hemangiomas were treated with 5 Gy in the five-fraction regimen. In patients with more than 3 years of follow-up, the obliteration rate was 88% for complex arteriovenous malformations (AVMs) treated with hfGKRS because of eloquent locations, whereas it was 62% for Spetzler-Martin grade 4-5 AVMs. For non-AVM pathologies (meningiomas, schwannomas, pituitary adenomas, paragangliomas, hypothalamic hamartomas, etc.), the 5-year progression free survival was 95%. Tumor failure was noted in 0.05% patient population. Radiation necrosis developed in 8.1% patients, and radiation-induced brain edema developed in 12% patients. It was resistant to treatment in 4% patients. No patient developed radiation-induced malignancy. Hypo-fractionation did not provide any hearing improvement in giant vestibular schwannomas. hfGKRS is a valuable standalone treatment option for candidates unsuitable for single-session GKRS. The dosing parameters need to be tailored as per the pathology and neighboring structures. It provides comparable results to single-session GKRS with an acceptable safety and complication profile.

Prognostic Factors of Facial Nerve Function After Giant Vestibular Schwannomas Surgeries. A single center perspective

Prognostic Factors of Facial Nerve Function After Giant Vestibular Schwannomas Surgeries. A single center perspective

Factors associated with giant vestibular schwannoma size.

Factors associated with giant vestibular schwannoma size.

Is Preoperative Facial Palsy a Deterrent to Facial Nerve Preservation after Gross-Total Removal of Giant Vestibular Schwannomas?

Abstract Background Although rare in small vestibular schwannomas, preoperative facial nerve paresis is often present in giant schwannomas. Preserving facial nerve function in these cases remains a herculean task. This study evaluates the facial functions after complete tumor removal and whether preoperative facial nerve involvement affects postoperative functional status. Methods This retrospective study from January 2014 to August 2021 excluded nongiant tumors (&lt; 4 cm), neurofibromatosis type 2 cases, incomplete removals, redo surgeries, deaths, and cases done without nerve monitoring. These were grouped into preoperative facial palsy present (PFP) and no preoperative facial palsy (NFP). Facial nerve functions were assessed on first postoperative day, at the time of discharge, and at last follow-up and dichotomized into two groups: nondisfiguring (House–Brackmann [HB] grades I–III) and disfiguring (HB grades IV–VI). The cohort outcomes of patients with nondisfiguring PFP (HB grades I–III) were also analyzed. Results There were 88 cases (PFP, n = 57; NFP, n = 31). Facial nerve was preserved anatomically in 62 (70.45%) patients (PFP, n = 38; NFP, n = 24) without any statistical difference (p = 0.29). Statistically significant disfiguring facial outcomes (HB IV, V, VI) were seen in patients with preoperative facial palsy (p = 0.01); however, a comparison of facial functions in patients with only nondisfiguring PFP with those in NFP group did not show the statistical difference (p = 0.12). Conclusions Facial nerve palsy present before surgery does not seem to be a deterrent to intraoperative preservation of facial nerve during complete removal of giant vestibular schwannomas. Patients with nondisfiguring facial palsies have postoperative facial functions comparable to those without facial palsy.

Early reinnervation of facial muscles after removal of large and giant vestibular schwannomas

Removal of large and giant vestibular schwannomas is associated with the risk of paresis of facial muscles. The probability of anatomical damage to the facial nerve is 10.3–14.0%. Treatment of mimic muscle paralysis is one of the most difficult problems in reconstructive surgery. In this study, the results of neurotization of the facial nerve by masticatory were evaluated in 4 patients after its damage during the removal of large and giant vestibular schwannomas. Neurotization was carried out 10–14 days after tumor removal. With direct neurotization of the facial nerve by masticatory in all patients, it was possible to achieve the function of mimic muscles, corresponding to grade II–III according to the House–Brackmann scale. The use of an autoinsert from the greater ear nerve led to a worse result (House–Brackmann IV).

Case Report: Extensive Temporal Bone Invasion in a Giant Vestibular Schwannoma

BackgroundRare giant vestibular schwannomas (GVSs) invade the temporal bone extensively, which carries unique risks for surgery owing to their complicated relationship with adjacent structures, difficult dissection of the temporal bone, and high risk of complications. The underlying mechanism of this invasive behavior remains unknown.Case descriptionWe report on a 28-year-old woman who presented with typical hearing loss and facial paralysis (House-Brackmann II). Magnetic resonance imaging exhibited a giant mass (∼5.0 cm) in the right cerebellopontine angle (CPA), petrous apex, and middle cranial fossa. Her primary diagnosis was GVS with petrous apex invasion. With the aid of presurgical imaging reconstruction and intraoperative facial nerve monitoring, we adopted a sequential therapeutic strategy, which included microsurgery for the CPA lesion followed by gamma knife radiosurgery (GKRS) for the petrous mass. During follow-up, stable tumor control was achieved with functional preservation of the facial nerve and no other complications. The postoperative immunohistochemical examination demonstrated dramatic intratumoral inflammation, which suggested its potential role in bony erosion. We reviewed the literature of large vestibular schwannoma with a petrous invasion and further discussed its treatment.ConclusionMicrosurgery remains the top therapeutic strategy for GVS. However, gross total resection with functional preservation of cranial nerves is challenging to achieve once the temporal bone is involved. In this case, we applied a planned and sequential approach of microsurgery and GKRS with a promising outcome, which highlighted this combinational strategy in this rare situation. In addition, pathological examination suggested that intratumoral inflammation might play a role in the bony erosion of GVS. Longer observation and more cases are needed to further investigate its molecular mechanism and treatment plan.

Extra-Arachnoidal Dissection and Limited Meatal Drilling for Excision of Giant Vestibular Schwannomas: Improved Facial Nerve Preservation.

Surgical excision of giant (>4 cm size) vestibular schwannomas (VS) with preservation of facial nerve (FN) function remains a challenge. Our surgical technique using an extra-arachnoid plane of dissection and limited meatal drilling is described with the goal of improving FN preservation. Surgical results with respect to FN preservation were analyzed for two groups of giant VS patients: Group A-operated between 2002 and 2009 using "standard" surgical technique, group B-operated between 2009 and 2016 using extra-arachnoidal dissection and limited meatal drilling. All patients had a minimum follow-up of 1 year. Of the 115 patients, total excision was possible in 103 (89.5%), near-total in 7 (6%), and subtotal in 5 (4.3%) patients. At a >6-month follow-up, 68 (59.1%) patients had good FN function (House-Brackmann [H&B] grades 1-2), while 21 (18.3%) patients had poor function (H&B grade 3-5). Grade 6 involvement was seen in 26 (22.6%). Five patients had lower cranial nerve impairment necessitating tracheostomy. Of the 98 patients, total excision was achieved in 70 (71.4%) patients, near-total in 9 (9.2%), and subtotal in 19 (19.4%). Four patients had repeat surgery; 14 underwent gamma-knife radiosurgery. At >6-month follow-up, 78 (79.5%) patients had good FN function (H&B grades 1-2), while 20 (20.4%) had poor function (H&B grade 3-5). With our 'modified' surgical technique of extra-arachnoidal dissection of VS throughout surgery and limited meatal drilling, an improved rate of functional FN preservation was observed.

CT-Based Intraoperative Navigation for Quick Identification of the Stylomastoid Foramen During Hypoglossal-Facial Nerve Anastomosis.

To present the ability of standard intraoperative neuronavigation to reliably identify the stylomastoid foramen, thus providing a quick and effective recognition of the facial nerve at its exit from the skull base. We describe the technical nuances of this procedure by presenting two surgical cases who underwent hypoglossal-facial nerve anastomosis for complete facial nerve palsy occurring post removal of a giant vestibular schwannoma 6 months earlier. CT-based neuronavigation allowed a quick and reliable identification of the stylomastoid foramen and of the facial nerve at its exit from the skull. The entire procedure lasted for 3 hours. Three months after the anastomosis, the first signs of facial muscle reinnervation were visible. The use of neuronavigation during hypoglossal-facial nerve anastomosis is a simple and cost-effective strategy to decrease operative duration and increase surgical effectiveness.

Surgical Outcome of Giant Vestibular Schwannomas: A Retrospective Analysis

Abstract Background Giant vestibular schwannomas, more than 4.5 cm in diameter, are still representing the majority of vestibular schwannomas in developing countries. The philosophy of incomplete and intracapsular tumor excision has been introduced in the management of these giant tumors, balancing the long-term tumor control and postoperative clinical outcome. Objective The aim was to review the cases with giant vestibular schwannomas and studying their prevalence, morbidity, and mortality rates. Patients and Methods This study was conducted retrospectively on data of patients who had undergone microsurgical excision of vestibular schwannomas in our institute between January and December 2017. The functional outcome of the patients was assessed by comparing the preoperative and the postoperative neurological examination, as well as the Karnofsky performance score. Results Twenty-two cases with vestibular schwannomas were included in this study. Among these 22 cases, 15 cases had giant vestibular schwannomas (68.2%). The tumors’ largest extracanalicular diameters ranged from 4.5 cm to 6.2 cm. Postoperative images showed gross total excision of the tumor in 11 cases (73.3%), and subtotal excisions in four cases (26.7%). Twelve cases (80%) had postoperative facial palsy. We encountered no mortality in our cases and three cases (20%) were symptom-free postoperatively (apart from hearing affection). Conclusion Large and giant vestibular schwannomas are still commonly met in neurosurgical practice in developing countries; they have different behaviors and presentations from those of smaller tumors. Both patient and surgeon expectations from surgery should be toward no mortality and mild or no morbidities.

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

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

Microsurgery for Vestibular Schwannoma via Retrosigmoid Transmeatal Approach with Intraoperative Monitoring Techniques.

Background: Functional preservation of cranial nerves remains an issue in surgical treatment of vestibular schwannoma.Aims: To explore the functional outcomes of vestibular schwannoma removed by microsurgery via a retrosigmoid transmeatal approach with intraoperative monitoring techniques.Study Design: A retrospective cross-sectional study was conducted on a group of patients with vestibular schwannoma operated by microsurgery.Methods: The outcomes, including the extent of tumor removal, the anatomic positions of the facial nerve, and postoperative Karnofsky performance status score, facial nerve function, and hearing function were reviewed and were statistically compared among tumor sizes (small, medium, and giant) and intraoperative monitoring types [electrophysiological monitoring only (E), electrophysiological monitoring + intraoperative imaging examination (E+I), and electrophysiological monitoring + neuronavigation (E+N)].Results: A total of 436 patients with VS received microsurgery. The position of the facial nerve was anterior in 85.5% of cases with small vestibular schwannoma. Other position patterns, especially anterior–superior and anterior–inferior, increased in tumors > 2.0 cm. Total resections were performed in all patients with small vestibular schwannoma. A total of 98.1% and 84.8% of patients with medium and giant vestibular schwannoma, respectively, had total resections. More than 90% of patients in all of the 3 monitoring groups had total resections. More than 80% of patients had excellent Karnofsky performance status score regardless of tumor size and monitoring type. After surgery, 100%, 84.4%, and 59.8% of patients with small-, medium-, and giant-sized vestibular schwannoma, respectively, had good facial nerve function. More than 70% of patients in all of the 3 monitoring groups had good facial nerve function postoperatively. The hearing preservation rate was 26.7% and 7.7% in small- and medium-sized vestibular schwannoma, respectively, and was 21.6% and 27.3% in the E group and the E+N group, respectively. The statistical analyses showed that tumor size was significantly associated with the extent of tumor resection, facial nerve localization, complications, postoperative Karnofsky performance status score, facial nerve function, and hearing function (all P ≤ .001). Monitoring type was significantly associated with the extent of resection (P ≤ .001). Additionally, patients in the E+N group had higher total resection rates than those in the E group (P ≤ .001). No cerebrospinal fluid leakage and surgery-related death occurred.Conclusion: In vestibular schwannoma microsurgery, tumor size is an important parameter that affects the localization of the facial nerve, the extent of resection, postoperative outcomes and complications. Intraoperative electrophysiological techniques combined with neuronavigation may be helpful to improve the extent of resection.

"Large and giant vestibular schwannomas: overall outcomes and the factors influencing facial nerve function".

(1) To study the overall outcomes of patients surgically treated for large/giant vestibular schwannomas (VSs) and (2) to identify and analyze preoperative and intraoperative prognostic factors influencing facial nerve (FN) outcome. A retrospective clinical study was conducted at a quaternary referral otology and skull-base center. A total of 389 cases were enrolled. The inclusion criteria were patients with tumor > 30mm undergoing surgery with a minimum follow-up of 12months. Neurofibromatosis-II, previous radiotherapy, revision surgeries, preoperative FN House-Brackmann (HB) grade > I, partial resections, incomplete records, or those lost to follow-up for a minimum period of 1year were excluded. In addition, partial resections and cases where FN was sacrificed intraoperatively were also excluded and were analyzed separately. The mean duration of symptoms was 35.4months, pronounced more in elderly (58.3months) than in younger individuals (28.4months). Mean tumor diameter was 36mm and 52.7% was cystic. Total resection (TR), near total resection (NTR), and subtotal resections (STR) were achieved in 77.4%, 9.5%, and 13.2% of cases, respectively. Regrowth was observed only after STR (19.6%). Good (HB I-II), moderate (HB III), and poor (HB IV-VI) FN functions were observed in 36.8%, 51.7%, and 11.6% cases, respectively. Younger individuals underwent TR in 259 (86.9%) cases against 42 (46.2%) in elderly individuals. Non-total resections (NTR/STR) were performed in 49 (53.8%) cases in elderly as against 39(13.1%) in younger individuals. Good FN outcome was observed in 28 (57.1%) cases of non-total resections in elderly as against 13 (33.3%) cases in younger individuals. On multiple logistic regression analysis, size of the tumor, preoperatively prolonged duration of symptoms, profound deafness, and antero-superiorly located FN with respect to the tumor played a detrimental role in the final facial nerve outcome postoperatively. On the contrary, in large tumors (3-3.9cm), presence of vertigo/disequilibrium had a relatively better impact on final FN outcome. Partial resections accounted for 41(7.8%) cases and FN was interrupted in 71(13.6%) cases in total. Factors detrimental to better FN outcome were giant VSs (> 4cm), antero-superiorly located FN intratumorally, preoperatively prolonged duration of symptoms, and profound deafness. In large tumors (3-3.9cm), presence of vertigo/disequilibrium had a better impact on FN outcome. Understandably, cases with TR in comparison with NTR/STR had worse FN outcomes. In comparison with younger patients, elderly patients underwent higher NTR/STR resulting in better FN outcomes. The above factors can be used as prognosticators for patient counseling and surgical decision making.

Functional sparing surgery policy for giant vestibular schwannomas.

The objective of this study was to compare the tumour control and facial nerve outcome according to the therapeutic strategy, that is extent of resection and post-operative radiotherapy. Retrospective study of patients with a giant vestibular schwannoma surgically treated from 4 academic skull base centres. Extent of resection, neurological complications, facial nerve function, MRI follow-up and occurrence of complementary treatment were reviewed. Sixty patients were included from 2000 to 2018. Primary end points were comparison the tumour control rate and the post-operative House-Brackmann grade at last follow-up according to the extent of tumour removal (ie total or subtotal removal). Secondary end points were assessment risk factors of poor facial nerve function and comparison complication rate according to extent of tumour removal. Sixty patients had initial surgery at diagnosis. A total resection was realised in 21 cases and a subtotal resection in 39 cases. Thirteen patients needed further treatment. One patient had a recurrence and needed a second surgery 108months after the initial total resection surgery. Twelve patients underwent post-operative radiotherapy, for an evolutive residual tumour. Tumour control was more successful in the total resection group (log-rank test, P=.015). There was no tumour recurrence after post-operative radiotherapy. The facial nerve outcome was significantly better in the subtotal resection group (Mean House-Brackmann grade at last follow-up: 2.2±1.9) than in the total resection group (House-Brackmann grade: 3.5±2.2) (P=.033). Vestibular schwannoma with a cystic component had better facial nerve outcome (P=.0082). Other than facial paralysis, neurological complications were observed in six patients (10% of patients): lower cranial nerves dysfunction in five cases and hemiparesis in one case. Subtotal resection of giant vestibular schwannomas leads to favourable tumour control and facial nerve function and therefore seems to be a valuable strategy.

Radiomics-Based Prediction of Long-Term Treatment Response of Vestibular Schwannomas Following Stereotactic Radiosurgery.

Stereotactic radiosurgery (SRS) is one of the treatment modalities for vestibular schwannomas (VSs). However, tumor progression can still occur after treatment. Currently, it remains unknown how to predict long-term SRS treatment outcome. This study investigates possible magnetic resonance imaging (MRI)-based predictors of long-term tumor control following SRS. Retrospective cohort study. Tertiary referral center. Analysis was performed on a database containing 735 patients with unilateral VS, treated with SRS between June 2002 and December 2014. Using strict volumetric criteria for long-term tumor control and tumor progression, a total of 85 patients were included for tumor texture analysis. All patients underwent SRS and had at least 2 years of follow-up. Quantitative tumor texture features were extracted from conventional MRI scans. These features were supplied to a machine learning stage to train prediction models. Prediction accuracy, sensitivity, specificity, and area under the receiver operating curve (AUC) are evaluated. Gray-level co-occurrence matrices, which capture statistics from specific MRI tumor texture features, obtained the best prediction scores: 0.77 accuracy, 0.71 sensitivity, 0.83 specificity, and 0.93 AUC. These prediction scores further improved to 0.83, 0.83, 0.82, and 0.99, respectively, for tumors larger than 5 cm. Results of this study show the feasibility of predicting the long-term SRS treatment response of VS tumors on an individual basis, using MRI-based tumor texture features. These results can be exploited for further research into creating a clinical decision support system, facilitating physicians, and patients to select a personalized optimal treatment strategy.

Extra-Arachnoidal Dissection for Excision of Giant Vestibular Schwannomas: Improved Facial Nerve Preservation

Abstract INTRODUCTION Surgical excision of giant vestibular schwannomas with preservation of facial nerve function remains a challenge. A modified surgical technique using an extra-arachnoid plane of dissection and limited meatal drilling is described here with the goal of improving the rated of functional preservation of facial nerve. METHODS The clinical material was analyzed for two groups: Group A patients of giant vestibular schwannomas operated between 2002 and 2009 with the “standard” surgical technique, Group B- patients of giant vestibular schwannomas operated between 2009 and 2015 using the new technique of pure extra-arachnoid dissection and limited meatal drilling. RESULTS Group A: Of the 115 patients in this group, total excision was possible in 103 (89.5%), near total excision in 7 (6%) and partial excision in 5 (4.3%) patients. Anatomical preservation of 7th nerve was achieved in 87.8% of patients. House and Brackman grade 1 and grade 2 facial nerve function was present in 68 (59.1%) patients, grade 3 in 10 (8.7%), grades 4 and 5 in 11 (9.6%), and 26 (22.6%) had grade 6 facial nerve involvement. Group B: Of the 127 patients operated by this technique, details and long term follow-up was available for 98 patients. Total excision was achieved in 70 (71.4%) patients, near total excision in 9 (9.2%), and subtotal excision in 19 (19.4%) cases. Four patients had repeat surgery and 14 patients underwent gamma knife radiosurgery. At follow-up, 78 (79.5%) patients had grade 1 and 2 facial nerve involvement, while 20 (20.4%) patients continued to have a poor function (grade 3-5). CONCLUSION Extra-arachnoid dissection and limited meatal drilling resulted in an improved rate of functional facial nerve preservation.