Hypervascular vestibular schwannomas

Sporadic pediatric vestibular schwannoma: a case report in a 4-year-old boy

Sporadic vestibular schwannomas (VSs) are rare in children. When occurred in the pediatric population, they usually appear bilaterally and are related to neurofibromatosis type 2 (NF2). The current study reports a 4-year-old boy without family history of VS or NF2 who presented with a large (5.7-cm) VS involving the right cerebellopontine angle and internal auditory canal. Through seven-staged surgical interventions and two stereotactic γ‑knife radiosurgery, the disease was stabilized. At 2-year follow-up, the child had right ear hearing loss, grade IV facial palsy, and normal motor function and gait. No definite evidence of gene mutation regarding NF2 can be identified after sequence analysis and deletion/duplication testing. This case highlights the significance of considering the possibility of sporadic VSs, even in very young children. It emphasizes the importance of not overlooking initial symptoms, as they may indicate the presence of a large tumor and could potentially result in delayed diagnosis.

The Importance of Intratumoral Venous Drainage Preservation in Two-Stage Surgery of Large Hypervascular Choroid Plexus Papilloma: A Case Report

Two-stage surgery may be necessary when total tumor removal cannot be accomplished in the first surgery; however, the extent and condition in which the remaining tumor should be before the next surgery have not yet been established. There is a risk of postoperative hemorrhage in the residual tumor, especially in hypervascular tumors. We report a case of hypervascular choroid plexus papilloma (CPP) in a 22-year-old male patient where the preservation of intratumoral venous drainage was considered important to avoid hemorrhagic complications during a two-stage surgery. In the first surgery, it was difficult to control the bleeding from the debulked tumor, and the surgery was terminated due to severe blood loss. Large draining veins running in the tumor were preserved as it was suspected that these were important drainage routes of the bloodstream of the tumor. The preserved draining red veins changed to normal venous color in the second surgery performed after one week. The residual tumor was not vascularized during the second surgery and underwent gross total resection with less blood loss. The patient was discharged without sequelae. There was no recurrence of the tumor and no neurological deficit during the three-year follow-up. To prevent postoperative hemorrhage associated with a residual tumor, it may be important to preserve venous drainage of the tumor in hypervascular tumor resection.

Growth potential of small residual tumors after vestibular schwannoma surgery: comparison between remnants and the natural history of small tumors

OBJECTIVE

Due to the heterogeneous definitions of tumor regrowth and various tumor volume distributions, the nature of small remnants after vestibular schwannoma (VS) surgery and the appropriate timing of adjuvant stereotactic radiosurgery for these remnants remain unclear. In this study, the growth potential of small remnants (< 1 cm3) after VS surgery was compared with that of treatment-naïve (TN) small VSs.

METHODS

This retrospective single-center study included 44 patients with VS remnants following subtotal resection (STR) of a large VS (remnant group) and 75 patients with TN VS (< 1 cm3; TN group). A 20% change in tumor volume over the imaging interval indicated radiographic progression or regression. Tumor progression-free survival (TPFS) rates were estimated using the Kaplan-Meier method.

RESULTS

In the remnant group, the mean preoperative tumor volume was 13.8 ± 9.0 cm3 and the mean tumor resection rate was 95% ± 5%. The mean tumor volume at the start of the observation period did not differ significantly between the two groups (remnant vs TN: 0.41 ± 0.29 vs 0.34 ± 0.28 cm3, p = 0.171). The median periods until tumor progression was detected were 15.1 (range 4.9-76.2) months and 44.7 (range 12.6-93.2) months in the TN and remnant groups, respectively. In the remnant group, the TPFS rates were 74% and 70% at 3 and 5 years after the surgery, respectively, compared with 59% and 47% in the TN group. The log-rank test demonstrated a significant difference (p = 0.008) in the TPFS rates between the two groups. Furthermore, 42 patients each from the remnant and TN groups were matched based on tumor volume. TPFS was significantly longer in the remnant group than in the TN group (3-year rates, 77% vs 62%; 5-year rates, 73% vs 51%; p = 0.02). In the remnant group, 18% of the tumor remnants demonstrated regression during follow-up, compared with 9% in the TN group, but this intergroup difference was not significant (p = 0.25).

CONCLUSIONS

This study demonstrated that the growth potential of small VS remnants was lower than that of TN tumors. Observing for small remnants may be appropriate after STR of a large VS. Given the risk of tumor regrowth, careful observation using MRI should be mandatory during follow-up.

Perfusion-weighted imaging in vestibular schwannoma: the influence that cystic status and tumor size have on perfusion profiles

Objective

The perfusion profile of vestibular schwannomas (VSs) and the factors that influence it have yet to be determined.

Materials and Methods

Twenty patients with sporadic VS were analyzed by calculating parameters related to the extravascular extracellular space (EES)-the volume transfer constant between a vessel and the EES (Ktrans); the EES volume per unit of tissue volume (Ve); and the rate transfer constant between EES and blood plasma (Kep)-as well as the relative cerebral blood volume (rCBV), and by correlating those parameters with the size of the tumor and its structure (solid, cystic, or heterogeneous).

Results

Although Ktrans, Ve, and Kep were measurable in all tumors, rCBV was measurable only in large tumors. We detected a positive correlation between Ktrans and rCBV (r = 0.62, p = 0.031), a negative correlation between Ve and Kep (r = -0.51, p = 0.021), and a positive correlation between Ktrans and Ve only in solid VSs (r = 0.64, p = 0.048). Comparing the means for small and large VSs, we found that the former showed lower Ktrans (0.13 vs. 0.029, p < 0.001), higher Kep (0.68 vs. 0.46, p = 0.037), and lower Ve (0.45 vs. 0.83, p < 0.001). The mean Ktrans was lower in the cystic portions of cystic VSs than in their solid portions (0.14 vs. 0.32, p < 0.001), as was the mean Ve (0.37 vs. 0.78, p < 0.001). There were positive correlations between the solid and cystic portions for Ktrans (r = 0.71, p = 0.048) and Kep (r = 0.74, p = 0.037).

Conclusion

In VS, tumor size appears to be consistently associated with perfusion values. In cystic VS, the cystic portions seem to have lower Ktrans and Ve than do the solid portions.

Postoperative Intratumoral or Peritumoral Hematomas After Vestibular Schwannoma Resection

BACKGROUND

Surgical removal of a vestibular schwannoma is a complex and challenging procedure, which may be complicated by development of postoperative hematomas, particularly after incomplete resection of the tumor.

OBJECTIVE

To investigate the occurrence of postoperative intra- or peritumoral hematomas after surgery for a vestibular schwannoma.

METHODS

This retrospective study evaluated 49 patients (age range 17-78 years) with a vestibular schwannoma, who were treated surgically via the lateral suboccipital approach between 2011 and 2016. The tumors ranged in size from 0 mm (in a case of an intracanalicular lesion) to 56 mm. In 30 cases (61%), total or near-total resection was accomplished, and in 19 cases (39%), subtotal or partial resection was done. On the basis of their bleeding tendency during tumor removal, the patients were divided into a "less-bleeding" (38 cases; 78%) and a "more-bleeding" (11 cases; 22%) subgroups.

RESULTS

A maximal vestibular schwannoma diameter >30 mm, patient age >60 years, and more bleeding during tumor removal were significantly associated with incomplete (subtotal or partial) resection. In six cases (12%), serial computed tomography after surgery demonstrated a postoperative hematoma, which was caused by insufficient irrigation of the surgical field (in two cases) or resulted from peritumoral hemorrhage (in two cases), intratumoral hemorrhage (in one case), or both intra- and peritumoral hemorrhage (in one case). The latter patient required urgent reoperation. In all cases, postoperative hematomas occurred after incomplete (subtotal or partial) resection of a vestibular schwannoma, and their development was significantly associated with more bleeding during tumor removal.

CONCLUSION

For avoidance of postoperative hematomas, careful hemostasis is required after completion of vestibular schwannoma removal, especially in cases with incomplete resection and an excessive bleeding tendency of the tumor tissue.

Hypervascularized Large Vestibular Schwannomas: Single-Center Experience in a Series of Forty Cases

Background

Vestibular schwannomas (VS) are usually hypovascularized benign tumors. Large VS (Koos grade IV) with unusual vascular architecture are defined as hypervascular (HVVS); the excessive bleeding during microsurgery has a negative impact on results.

Methods

Forty consecutive patients were operated on for HVVS (group A). A tendency to bleed and adherence of capsule to nervous structures were evaluated by reviewing intraoperative video records. The cisternal facial nerve (FN) position was reported. Microsurgical removal was classified as total, near-total, subtotal, or partial and the MIB-1 index was evaluated in all. FN results were classified according to the House-Brackmann scale.

Results

Results of Group A were compared with those of 45 patients operated on for large low-bleeding VS (group B). Mean tumor diameter was 3.81 cm in group A and 3.58 cm in group B; the mean age was 42.4 and 56.3 years, respectively. The mean American Society of Anesthesiologists Physical Status Scale class of group A was 1.67 versus 2.31 of group B (P < 0.01). Total or near-total resection was accomplished in 76.5% of group A versus 73.3% of group B. Tight capsule adhesion was observed in 67.5% of group A versus 57.8% of group B. Mean MIB-1 was 1.25% and 1.08%, respectively.

FN anatomic preservation was possible in 84.6% of group A versus 95.5% of group B; 67.5% of group A had HB grade I or II FN outcome versus 93.3% of group B (P < 0.001). In group A, 8 patients (20.0%) experienced transient postoperative complications versus 4.4% of group B. Recurrence/regrowth was observed in 4 patients in group A versus 1 in group B.

Conclusions

Intraoperative video for classification of HVVS was used. Microsurgery of large HVVS was associated with higher (usually transient) complications and recurrence/regrowth rates and poorer FN outcome, especially in patients with tight capsule adhesion.

Primary pilocytic astrocytoma of the cerebellopontine angle in pediatric patient with neurofibromatosis type 1: a case report

Background

Cerebellopontine angle tumor (CPA) in pediatrics is rare as compared to adults. We describe a case of pediatric pilocytic astrocytoma presented as a right CPA mass with a concurrent clinical diagnosis of neurofibromatosis type 1 (NF1).

Case presentation

A 14-year-old boy with a newly diagnosed hypertension presented with a short history of headache and blurring vision. Neurological examination revealed bilateral papilloedema, partial right third nerve palsy and mild sensorineuronal hearing deficits. Skin examination identified multiple café au lait spots with cutaneous neurofibromas. Preoperative neuroimaging suggested the diagnosis of an extraaxial CPA mass consistent with meningioma, with obstructive hydrocephalus. A left ventriculoperitoneal shunt was inserted and the child was subjected for a suboccipital retrosigmoid approach for tumor resection. The histopathological features, however, were typical for pilocytic astrocytoma.

Conclusions

A careful evaluation of the clinical presentation and radiological images of CPA lesions is necessary prior to surgical embarkment. To the best of our knowledge, this case is the first report of pilocytic astrocytoma in the CPA in pediatric with NF1.

Imaging of the Vestibular Schwannoma: Diagnosis, Monitoring, and Treatment Planning

Appropriate imaging strategies for the detection, treatment planning, and posttreatment monitoring of vestibular schwannomas will be discussed. The typical and variant imaging appearances of vestibular schwannomas, as well as the imaging features that should prompt consideration of differential diagnoses, will be illustrated. Understanding the natural history of vestibular schwannomas, optimal measurement and definition of tumour growth helps the radiologist evaluate for the failure of conservative management and requirement for surgery or radiotherapy. In order to determine the success of conservative management, the radiologist is required to understand the natural history of vestibular schwannomas and how tumour growth is defined. Finally, the imaging features which help guide appropriate treatment with surgery or radiotherapy will be highlighted, and the expected posttreatment imaging changes will be described.

Prediction of blood supply in vestibular schwannomas using radiomics machine learning classifiers

This study attempts to explore the radiomics-based features of multi-parametric magnetic resonance imaging (MRI) and construct a machine-learning model to predict the blood supply in vestibular schwannoma preoperatively. By retrospectively collecting the preoperative MRI data of patients with vestibular schwannoma, patients were divided into poor and rich blood supply groups according to the intraoperative recording. Patients were divided into training and test cohorts (2:1), randomly. Stable features were retained by intra-group correlation coefficients (ICCs). Four feature selection methods and four classification methods were evaluated to construct favorable radiomics classifiers. The mean area under the curve (AUC) obtained in the test set for different combinations of feature selecting methods and classifiers was calculated separately to compare the performance of the models. Obtain and compare the best combination results with the performance of differentiation through visual observation in clinical diagnosis. 191 patients were included in this study. 3918 stable features were extracted from each patient. Least absolute shrinkage and selection operator (LASSO) and logistic regression model was selected as the optimal combinations after comparing the AUC calculated by models, which predicted the blood supply of vestibular schwannoma by K-Fold cross-validation method with a mean AUC = 0.88 and F1-score = 0.83. Radiomics machine-learning classifiers can accurately predict the blood supply of vestibular schwannoma by preoperative MRI data.

Hypervascular vestibular schwannoma: A case report and review of the literature

Vestibular schwannomas, also known as acoustic neuromas, are benign tumors that arise from Schwann cells near the transition from glial cells to Schwann cells. While most vestibular schwannomas are hypovascular tumors, a small percentage constitute the hemorrhagic and/or hypervascular vestibular schwannomas (HVS) subtype. We describe a case of a 36-year-old female who presented with nausea, vomiting, and an acute decrease in vision in her right eye. Computed tomography of the head demonstrated a hemorrhagic lesion in the right hemisphere with evidence of ventricular effacement. Follow-up magnetic resonance imaging revealed a mass in the right cerebellopontine angle that was hypointense on T1-weighted imaging and mild hyperintense heterogeneous signal on T2-weighted imaging, suggestive of a hemorrhagic vestibular schwannoma. It is important for radiologists to recognize the unique clinical and radiological features of HVS in the initial diagnostic assessment of cerebellopontine angle tumors and to distinguish it from common (hypovascular) vestibular schwannomas and other related pathologies. A preoperative diagnosis of HVS allows clinicians to become familiar with the unique characteristics of the tumor and to devise a feasible operative strategy prior to surgical resection.

[Acoustic neurinomes of childhood]

The article presents a review of the literature on the vestibular schwannoma of childhood, the features of its clinical manifestations, diagnostic methods, methods of treating education and indications for their use.

Pediatric vestibular schwannomas: case series and a systematic review with meta-analysis

OBJECTIVE

Sporadic unilateral vestibular schwannomas are rare in the pediatric population. Little has been reported in the literature on the presentation, tumor size, response to surgical treatment, and recurrence rates in these younger patients. The authors' goal was to describe their institutional experience with pediatric sporadic vestibular schwannomas and to conduct a meta-analysis of the existing literature to provide further insight into the presentation, tumor characteristics, and surgical outcomes for these rare tumors to help direct future treatment strategies.

METHODS

The authors performed a retrospective review of all patients 21 years of age or younger with unilateral vestibular schwannomas and without neurofibromatosis type 2 who underwent resection by the senior authors between 1997 and 2019. A systematic review of the literature and meta-analysis was also performed by entering the search terms "pediatric" and "vestibular schwannoma" or "acoustic neuroma," as well as "sporadic" into PubMed. Presentation, treatment, clinical outcomes, and follow-up were analyzed.

RESULTS

Fifteen patients were identified at the authors' institution, ranging in age from 12 to 21 years (mean 16.5 years). Common presenting symptoms included hearing loss (87%), headache (40%), vertigo (33%), ataxia (33%), and tinnitus (33%). At the time of surgery, the mean tumor size was 3.4 cm, with four 1-cm tumors. Four patients had residual tumor following their first surgery, 3 (75%) of whom had significant radiographic regrowth that required further treatment. The literature review identified an additional 81 patients from 26 studies with patient-specific clinical data available for analysis. This resulted in a total of 96 reported patients with an overall average age at diagnosis of 12.1 years (range 6-21 years) and an average tumor size of 4.1 cm.

CONCLUSIONS

Pediatric vestibular schwannomas present similarly to those in adults, although symptoms of mass effect are more common, as these tumors tend to be larger at diagnosis. Some children are found to have small tumors and can be successfully treated surgically. Residual tumors in pediatric patients were found to have a higher rate of regrowth than those in their adult counterparts.

Arterial spin labeling imaging correlates with the angiographic and clinical vascularity of vestibular schwannomas

PURPOSE

Hypervascular vestibular schwannomas (HVSs) are a type of the vestibular schwannomas (VSs) that are extremely difficult to remove. We examined whether HVSs can be predicted by using arterial spin labeling (ASL) imaging.

METHODS

A total of 103 patients with VSs underwent ASL imaging and digital subtraction angiography (DSA) before surgery. Regional cerebral blood flow (CBF) of gray matter and regional tumor blood flow (TBF) were calculated from ASL imaging, and we defined the ratio of TBF to CBF as the relative TBF (rTBF = TBF/CBF). Angiographic vascularity was evaluated by DSA, and clinical vascularity was evaluated by the degree of intraoperative tumor bleeding. Based on the angiographic and clinical vascularity, the VSs were divided into two categories: HVS and non-HVS. We compared rTBF with angiographic and clinical vascularities, retrospectively.

RESULTS

The mean rTBFs of angiographic non-HVSs and HVSs were 1.29 and 2.58, respectively (p < 0.0001). At a cutoff value of 1.55, the sensitivity and specificity were 93.9% and 72.9%, respectively. The mean rTBFs of clinical non-HVS and HVSs were 1.45 and 2.22, respectively (p = 0.0002). At a cutoff value of 1.55, the sensitivity and specificity were 79.4% and 66.7%, respectively.

CONCLUSION

The rTBF calculated from ASL imaging correlates well with tumor vascularity and may be useful for predicting HVSs before surgery.

Hypervascular Vestibular Schwannomas: Clinical Characteristics, Angiographical Classification, and Surgical Considerations

BACKGROUND

There is a rare type of vestibular schwannoma, scarcely discussed in the literature, known as a hypervascular vestibular schwannoma (HVS).

OBJECTIVE

To evaluate its biological characteristics, angiographical classification, surgical outcomes, and the significance for surgical consideration, using a large series of this clinical entity.

METHODS

The definition for HVS in this study was the tumor stain from the vertebrobasilar system (VBS) in angiography. The authors conducted a retrospective analysis of 36 patients who were angiographically diagnosed with HVS and underwent surgery between 2008 and 2015. Their biological findings and their surgical outcomes were compared with non-HVS subjects. With regard to the tumor feeders and AV shunt, we classified HVS into 5 types.

RESULTS

HVS occurred more commonly in younger subjects (mean: 39.4 yr), as a larger solid tumor with multiple flow voids (mean: 34.1 mm), and involved higher levels of cerebrospinal fluid protein (mean: 202 mg/dl) and a higher MIB1-index (mean: 4.3%). The average resection rate for these 36 cases was 95.3%, and recurrence was seen in 6 cases (16.7%). Compared with non-HVS, the extent of tumor resection was significantly lower, and the recurrence rate was significantly higher. Especially in HVS type 2B (the tumor stain is fed by the VBS and the external carotid artery, with an arteriovenous shunt from the VBS), the recurrence-free survival duration was significantly shorter compared with other HVS types and non-HVS, and HVS type 2B exhibited an identifiable risk factor for recurrence.

CONCLUSION

HVS have the distinct clinical characteristics compared with those of non-HVS subjects.

Hypervascular Lesions of the Cerebellopontine Angle: The Relevance of Angiography as a Diagnostic and Therapeutic Tool and the Role of Stereotactic Radiosurgery in Management. A Comprehensive Review

BACKGROUND

The cerebellopontine angle (CPA) is a narrowed skull base area containing important cranial nerves and vessels and bordering with eloquent areas of the posterior fossa. Tumors of the CPA are a heterogeneous group and can have extradural, intradural/extra-axial, or intra-axial origins. Their vascular supply changes depending on their anatomic origin. Symptomatic, large CPA tumors require surgical resection in order to prevent irreversible, severe neurological damages. However, its tight and strategical location make surgery in the CPA very challenging and require appropriate pre-surgical planning. Pre-surgical diagnosis is of great importance as it allows us to choose the optimal management for the particular patient. This is of further significance when encountering high-risk lesions such as hypervascular tumors. Neurosurgeons should utilize every available pre-surgical diagnostic modalities as well as neo-adjuvant treatments in order to reduce such risks.

METHODS

We review all reported cases of hypervascular lesions of the CPA and discuss the roles of angiography and stereotactic radiosurgery in their management.

RESULTS

Three lesions of the CPA can be considered as truly hypervascular: hemangioblastomas, hemangiopericytomas and paragangliomas. All lesions share many radiological features. However, each lesion has a different anatomical origin and hence, has a characteristic vascular supply. Pre-surgical angiography can be utilized as a diagnostic tool to narrow down the differential diagnosis of a vascular CPA lesion, based on the predominant supplying vessel. In addition, pre-surgical embolization at time of angiography will narrow the associated surgical risks.

CONCLUSIONS

Angiography is a crucial diagnostic and therapeutic tool, helping both in narrowing the presurgical differential diagnosis and in controlling intraoperative bleeding. Because of the high surgical risks associated with resection of vascular tumors in the CPA, noninvasive treatments, such as stereotactic radiosurgery, also may have a crucial role.

Intracranial Capillary Hemangioma in the Posterior Fossa of an Adult Male

Intracranial capillary hemangioma (ICH) is a rare entity, with approximately 24 reported cases in the literature. There are only three reported cases of ICH in an adult male. In this case report, we describe the fourth documented case of ICH in an adult male and, to the best of our knowledge, the first ever documented case of ICH in the posterior fossa of an adult male. We also discuss its imaging appearance and differential diagnosis.

Jugular foramen schwannoma mimicking paraganglioma: case report and review of imaging findings

We present the case of a 30-year-old woman who presented with an 11-year history of chronic occipital headaches and a 12-month history of worsening difficulty speaking and/or swallowing, facial spasms, hearing loss, and dizziness. A large lytic mass was found centered in the left jugular foramen (JF) on computed tomography examination; follow-up magnetic resonance imaging showed an avidly enhancing mass with prominent central flow voids. Histopathologic examination after surgical resection revealed the mass to be a schwannoma. Prominent central vascularity is an unusual presentation for JF schwannomas. Our report provides a review of magnetic resonance imaging features of intrinsic JF lesions relevant to our case.

Medial acoustic neuromas: clinical and surgical implications

OBJECT

Medial acoustic neuroma is a rare entity that confers a distinct clinical syndrome. It is scarcely discussed in the literature and is associated with adverse features. This study evaluates the clinical and imaging features, pertinent surgical challenges, and treatment outcome in a large series of this variant. The authors postulate that the particular pathological anatomy with its arachnoidal rearrangement has a profound implication on the surgical technique and outcome.

METHODS

The authors conducted a retrospective analysis of 52 cases involving 33 women and 19 men who underwent resection of medial acoustic neuromas performed by the senior author (O.A.) over a 20-year period (1993-2013). Clinical, radiological, and operative records were reviewed, with a specific focus on the neurological outcomes and facial nerve function and hearing preservation. Intraoperative findings were analyzed with respect to the effect of arachnoidal arrangement on the surgeon's ability to resect the lesion and the impact on postoperative function.

RESULTS

The average tumor size was 34.5 mm (maximum diameter), with over 90% of tumors being 25 mm or larger and 71% being cystic. Cerebellar, trigeminal nerve, and facial nerve dysfunction were common preoperative findings. Hydrocephalus was present in 11 patients. Distinguishing intraoperative findings included marked tumor adherence to the brainstem and frequent hypervascularity, which prompted intracapsular dissection resulting in enhancement on postoperative MRI in 18 cases, with only 3 demonstrating growth on follow-up. There was no mortality or major postoperative neurological deficit. Cerebrospinal fluid leak was encountered in 7 patients, with 4 requiring surgical repair. Among 45 patients who had intact preoperative facial function, only 1 had permanent facial nerve paralysis on extended follow-up. Of the patients with preoperative Grade I-II facial function, 87% continued to have Grade I-II function on follow-up. Of 10 patients who had Class A hearing preoperatively, 5 continued to have Class A or B hearing after surgery.

CONCLUSIONS

Medial acoustic neuromas represent a rare subgroup whose site of origin and growth patterns produce a distinct clinical presentation and present specific operative challenges. They reach giant size and are frequently cystic and hypervascular. Their origin and growth pattern lead to arachnoidal rearrangement with marked adherence against the brainstem, which is critical in the surgical management. Excellent surgical outcome is achievable with a high rate of facial nerve function and attainable hearing preservation. These results suggest that similar or better results may be achieved in less complex tumors.

Short-term clinico-radiographic response to super-selective intra-arterial cerebral infusion of Bevacizumab for the treatment of vestibular schwannomas in Neurofibromatosis type 2

Neurofibromatosis type 2 (NF2) is an autosomal dominant syndrome with a prevalence of approximately 1 in 30,000. NF 2 is characterized by bilateral vestibular schwannomas, as well as meningiomas, ependymomas and gliomas. Currently, surgical resection and radiotherapy represent the mainstay of treatment, although new studies suggest a role for certain chemotherapeutic agents. Intravenous administration of Bevacizumab (Avastin, Genetech Pharmaceuticals) has been shown to be active in the treatment of vestibular schwannomas. The IV route of administration, however, carries a risk of known systemic side-effects such as bowel perforation, wound dehiscence and pulmonary embolism. In addition, the percentage of drug that reaches the tumor site may be restricted by the blood tumor barrier. This report describes the super-selective intra-arterial infusion of Bevacizumab following blood brain barrier disruption for the treatment of vestibular schwannomas in three patients with Neurofibromatosis type 2. It represents the first time such a technique has been performed for this disease. Additionally, this method of drug delivery may have important implications in the treatment of patients with vestibular schwannomas associated with Neurofibromatosis type 2.

The molecular biology and novel treatments of vestibular schwannomas

Vestibular schwannomas are histopathologically benign tumors arising from the Schwann cell sheath surrounding the vestibular branch of cranial nerve VIII and are related to the NF2 gene and its product merlin. Merlin acts as a tumor suppressor and as a mediator of contact inhibition. Thus, deficiencies in both NF2 genes lead to vestibular schwannoma development. Recently, there have been major advances in our knowledge of the molecular biology of vestibular schwannomas as well as the development of novel therapies for its treatment. In this article the authors comprehensively review the recent advances in the molecular biology and characterization of vestibular schwannomas as well as the development of modern treatments for vestibular schwannoma. For instance, merlin is involved with a number of receptors including the CD44 receptor, EGFR, and signaling pathways, such as the Ras/raf pathway and the canonical Wnt pathway. Recently, merlin was also shown to interact in the nucleus with E3 ubiquitin ligase CRL4(DCAF1). A greater understanding of the molecular mechanisms behind vestibular schwannoma tumorigenesis has begun to yield novel therapies. Some authors have shown that Avastin induces regression of progressive schwannomas by over 40% and improves hearing. An inhibitor of VEGF synthesis, PTC299, is currently in Phase II trials as a potential agent to treat vestibular schwannoma. Furthermore, in vitro studies have shown that trastuzumab (an ERBB2 inhibitor) reduces vestibular schwannoma cell proliferation. With further research it may be possible to significantly reduce morbidity and mortality rates by decreasing tumor burden, tumor volume, hearing loss, and cranial nerve deficits seen in vestibular schwannomas.

Beyond audiofacial morbidity after vestibular schwannoma surgery

Object

Outcomes following vestibular schwannoma (VS) surgery have been extensively described; however, complication rates reported in the literature vary markedly. In addition, the majority of reports have focused on outcomes related to cranial nerves (CNs) VII and VIII. The objective of this study was to analyze reported morbidity unrelated to CNs VII and VIII following the resection of VS.

Methods

The authors performed a comprehensive search of the English language literature, identifying and aggregating morbidity and death data from patients who had undergone microsurgical removal of VSs. A subgroup analysis based on surgical approach and tumor size was performed to compare rates of CSF leakage, vascular injury, neurological deficit, and postoperative infection.

Results

One hundred articles met the inclusion criteria, providing data for 32,870 patients. The overall mortality rate was 0.2% (95% CI 0.1–0.3%). Twenty-two percent of patients (95% CI 21–23%) experienced at least 1 surgically attributable complication unrelated to CNs VII or VIII. Cerebrospinal fluid leakage occurred in 8.5% of patients (95% CI 6.9–10.0%). This rate was markedly increased with the translabyrinthine approach but was not affected by tumor size. Vascular complications, such as ischemic injury or hemorrhage, occurred in 1% of patients (95% CI 0.75–1.2%). Neurological complications occurred in 8.6% of cases (95% CI 7.9–9.3%) and were less likely with the resection of smaller tumors (p < 0.0001) and the use of the translabyrinthine approach (p < 0.0001). Infections occurred in 3.8% of cases (95% CI 3.4–4.3%), and 78% of these infections were meningitis.

Conclusions

This study provides statistically powerful data for practitioners to advise patients about the published risks of surgery for VS unrelated to compromised CNs VII and VIII.

Prognostic significance of changes in the internal acoustic meatus caused by vestibular schwannoma

The prognostic significance of the variety of changes in the internal auditory meatus (IAM) caused by vestibular schwannoma was retrospectively analyzed in 69 consecutive patients with vestibular schwannoma. Preoperative bone-window computed tomography was used to classify IAM changes into extensive destruction (17%), widening (46%), and normal IAM (36%). Extensive destruction (47 +/- 19 years) and widening (48 +/- 13) occurred in significantly younger patients than normal IAM (59 +/- 9). Preoperative hearing was significantly more severely disturbed in patients with extensive destruction than in those with widening or normal IAM. IAM change was significantly related to the tumor consistency, as normal IAM was more common in patients with cystic tumor than in those with solid tumor. Postoperative hearing and facial function were worse in patients with severe IAM change, although the relationship between the IAM change and the surgical result was not significant. One patient with extensive destruction developed postoperative cerebrospinal fluid (CSF) leakage through the air cells around the IAM, and needed surgical repair. Severe IAM change occurs with solid tumor and causes severely disturbed preoperative hearing in younger patients, which reflects the tumor aggressiveness. Severe IAM change increases the technical difficulty of tumor removal and the risk of postoperative CSF leakage, and is associated with a poorer prognosis for patients with vestibular schwannoma.