Staged resection of large hypervascular vestibular schwannomas in young adults

Two-Stage Surgical Management for Acutely Presented Large Vestibular Schwannomas: Report of Two Cases

The surgical management of vestibular schwannomas should be based on their presentation, neuro-imaging findings, surgeons' expertise, and logistics. Multi-stage surgery can be beneficial for large-sized lesions with acute presentations. Herein, we highlighted the indications for two cases managed initially through the retrosigmoid and, subsequently, translabyrinthine approaches. The first case presented with acute balance and gait issues and a long history of hearing loss and blurred vision. Neuroimaging findings revealed a cerebellopontine angle lesion, resembling a vestibular schwannoma, with significant brainstem compression and hydrocephalus. Due to the rapidly deteriorating clinical status and large-sized tumor, we first proceeded with urgent decompression via a retrosigmoid approach, followed by gross total resection via a translabyrinthine approach two weeks later. The second case presented with gradually worsening dizziness and hemifacial numbness accompanied by acute onset severe headaches and hearing loss. Neuroimaging findings showed a large cerebellopontine angle lesion suggestive of a vestibular schwannoma with acute intratumoral hemorrhage. Given the acute clinical deterioration and large size of the tumor, we performed urgent decompression with a retrosigmoid approach followed by gross total resection through a translabyrinthine approach a week later. Post-surgery, both patients showed excellent recovery. When managing acutely presented large-sized vestibular schwannomas, immediate surgical decompression is vital to avoid permanent neurological deficits.

Surgical treatment for extremely rare solitary fibrous tumors of the central nervous system originating from cranial nerve VIII: new clinicopathological findings. Illustrative case

BACKGROUND

Reports of solitary fibrous tumors (SFTs) of the central nervous system (CNS) originating from cranial nerves are extremely rare. The origins of these neurogenic SFTs of the CNS have been determined only by intraoperative findings, and there is no pathological evidence of whether they really originated from cranial nerves.

OBSERVATIONS

A 54-year-old female with hearing loss and facial paralysis presented with a giant right cerebellopontine angle tumor. She was diagnosed with a petrous meningioma based on preoperative imaging, and the tumor was removed via the retrosigmoid approach after embolization of the tumor-feeding vessels. Intraoperatively, the tumor was not attached to the dura mater but extended from the internal auditory canal to the cisternal portion. The acoustic nerve was not identified, but it was possible to separate the tumor from the facial nerve. The tumor was removed as an acoustic schwannoma intraoperatively. Postoperative pathological examination revealed an SFT. Immunostaining revealed peripheral nerve bundles entrapped within the tumor tissue. The patient was diagnosed with an SFT of the CNS originating from the acoustic nerve.

LESSONS

A neurogenic SFT of the CNS was diagnosed based on both intraoperative and pathological findings.

Large Vestibular Schwannoma: A Two-Stage Surgery

Treatment of large vestibular schwannoma (VS) has historically centered on total resection of the lesion. Staged surgery has been used for VS that is highly vascularized, unexpected events during surgery, and thinned and stretched facial nerve with serious adherence causing difficult dissection. We present a case of a patient with a large VS resected through a two-stage surgery through the same retrosigmoid craniotomy.

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.

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.

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.

Staged resection for vestibular schwannoma

CONCLUSION

Surgery remains the preferred option for large vestibular schwannoma (VS). The presence of unpredictable intraoperative difficulties may convince the operator to suspend the surgery to avoid risks to patient life. Additional surgeries may be mandatory and are better performed using a transcochlear approach. High rates of complications, poor facial nerve results, and a percentage of incomplete removals should be expected in such unfavorable cases.

OBJECTIVES

To review the results for nine cases of huge VS treated by staged resection.

METHOD

A retrospective case review was performed for all nine patients who underwent staged resection of VS at the Gruppo Otologico between 1984-2012. The decision to perform staged surgery was always made intra-operatively after encountering unpredicted difficulties.

RESULTS

The nine patients represented 0.3% of all patients who underwent VS surgery during the same period. Mean tumor size was 4.7 cm (range = 3.0-6.6 cm). Two cases required three surgeries, resulting in a total of 20 operations. In addition, two cases required pre-operative ventriculoperitoneal shunt and one required temporary tracheotomy. After the final stage of surgery, complete removal had been achieved in six of the nine patients. The facial nerve was never preserved anatomically.

Growth of Primary and Remnant Vestibular Schwannomas: A Three-Year Follow-Up Study

OBJECTIVE

Vestibular schwannomas (VSs) are benign, slowly growing tumors. The management strategy, however, remains unclear for both primary VS and remnant VS after subtotal or partial resection. In this study, we analyzed the radiographical tumor growth to elucidate factors possibly predicting growth or regrowth of their tumors.

METHODS

We retrospectively analyzed the data of 76 patients with diagnoses of VS at a single tertiary academic referral center. The primary VS group consisted of 43 patients with conservative management, and the remnant VS group included 33 patients with tumor remnant after surgery. All patients were followed up with serial magnetic resonance imaging without intervention. The primary end point in this study was significant tumor growth at the end of the 3-year follow-up period.

RESULTS

Multivariate analysis revealed that remnant VS was less likely to grow than primary VS (odds ratio: 0.27, 95% confidence interval: 0.09-0.84). Tumor volume was correlated with tumor growth; larger tumors grew more frequently than small tumors in both primary and remnant VS groups with marginal (P = 0.05) and definite (P = 0.007) significance, respectively. The receiver operating characteristic curves plotted for tumor growth identified the optimum cutoff points of tumor volumes with greater sensitivity and specificity for remnant VS than for primary VS (sensitivity: 80% vs. 59%, specificity: 87% vs. 76%, respectively).

CONCLUSIONS

Small remnant VS after surgery could be conservatively managed without additional treatment, and relatively large remnant VS should be followed up with close serial imaging or might be a possible candidate for radiosurgery during the early postoperative period.

Staging in giant vestibular schwannoma surgery: A two consecutive day technique for complete resection in basic neurosurgical setups

Introduction:

Vestibular schwannomas constitute 8% of all intracranial tumors. A majority of vestibular schwannomas are sporadic and unilateral. Giant vestibular schwannomas are seen in our country due to the late diagnosis and long duration of symptoms before diagnosis. These giant schwannomas are challenging to manage as most of the patients are having brainstem compression.

Materials and Methods:

Twelve cases of a giant vestibular schwannoma were operated in our department between May 2011 and December 2012. Vestibular schwannomas with a maximal diameter of more than 4 cm were defined as a giant vestibular schwannoma. All the patients had a unilateral vestibular schwannoma. Performance status of all the patients were graded as per the Karnofsky performance score. Pre-operative assessment of 5^th, 7^th, 8^th and lower cranial nerve status was done in all cases. Ventriculoperitoneal shunting was done pre-operatively in all cases. All patients were operated through retromastoid suboccipital craniectomy and retrosigmoid approach. These patients were operated in two stages in two consecutive days with overnight elective ventilation in ICU. Ultrasonic aspirator and nerve monitoring techniques were not used.

Results:

Giant acoustic schwannomas can be safely resected completely by a staged resection on two consecutive days without any increased morbidity or mortality. This technique may be employed to achieve complete resection of such lesions without deterioration of facial nerve function in institutions which do not have advanced facilities like nerve monitoring or ultrasonic aspirator.

Preoperative vincristine for an inoperable choroid plexus papilloma: a case discussion and review of the literature

The authors report the case of a 14-month-old boy with a large right intraventricular choroid plexus papilloma (CPP) for which the first attempt at resection resulted in life-threatening intraoperative hemorrhage. The tumor was unsuitable for embolization, and neoadjuvant ifosfamide, carboplatin, etoposide (ICE) chemotherapy had no effect on tumor size. However, chemotherapy with vincristine, although not impacting on CT perfusion parameters, resulted in a significant decrease in tumor size, enabling complete resection with manageable blood loss. The mechanism underlying the effect of vincristine in this case is uncertain, but it is a treatment strategy that warrants further evaluation for the treatment of CPPs that are not amenable to embolization.

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.

Functional outcome after complete surgical removal of giant vestibular schwannomas

OBJECT

The authors evaluated the outcome of radical surgery in a consecutive series of patients with giant vestibular schwannomas (VSs).

METHODS

Fifty patients with VSs > 4.0 cm in maximal extrameatal diameter were included in this retrospective study (Group A). The group was compared with a matched group of 167 patients with VSs < 3.9 cm (Group B). In all cases the retrosigmoid approach was used. Outcome measures included completeness of tumor removal, facial nerve function, hearing, and the surgery-related complication rate.

RESULTS

The mean tumor size in Group A was 4.4 cm and that in Group B was 2.3 cm. Total removal was achieved in all Group A patients and in 97.6% of Group B patients. The anatomical integrity of the facial nerve was preserved in 92% in Group A and in 98.8% in Group B. At last follow-up 75% of the patients with giant VSs had excellent or good facial nerve function, 19% had fair function, and 6% had poor function. In 33% of patients (3 cases) with good preoperative hearing level, it was preserved. Newly developed lower cranial nerve dysfunction occurred in 3 patients but proved to be temporary in 2 of them. A CSF leak developed in 6% of those who not previously undergone surgery. Compared with Group B, a significant difference was found only in the rates of the following parameters: excellent facial nerve function, useful and good hearing, lower cranial nerve dysfunction, and blood collection (p < 0.05). The perioperative mortality rate in both groups was 0%.

CONCLUSIONS

In patients with a giant VS, total tumor removal can be achieved via the retrosigmoid approach with a 0% mortality rate and low morbidity rate, especially with regards to facial nerve function. In selected cases even hearing preservation is possible. Tumor size significantly correlates with postoperative outcome.

Staging in vestibular schwannoma surgery: a modified technique

The authors herein propose the staged excision as a novel strategy to preserve facial nerve and minimize complication during microsurgery of large vestibular schwannoma (VS). At the first stage, for reducing mass effect on the brain stem and cerebellum, subtotal tumor resection was performed via a retrosigmoid craniotomy without intervention of meatal portion of tumor. With total resection of the remaining tumor, the facial nerve was decompressed and delineated during the second stage translabyrinthine approach at a later date. A 38-year-old female who underwent the staging operation for resection of her huge VS is illustrated.

Surgery of extra-axial tumors of the cerebral base

Because of the complex structure of the cranial base and its close proximity to cranial nerves and vessels, surgery in this area is associated with considerable risk of morbidity and mortality. Multiple approaches to each part of the cranial base have been developed over the past few decades, ranging from small modifications of more traditional approaches to complex and sophisticated new techniques. However, experience has shown that optimal outcome is achieved if the selected approach is not associated with significant approach-related morbidity. Furthermore, not all cranial base tumors can be cured by surgery. The selection of operative approach and the goal of surgery should be part of the whole treatment strategy. The attempt to achieve complete resection can, therefore, be justified only if the associated long-term morbidity is minimal. Refinements of the traditional retrosigmoid suboccipital approach have made it the most effective and safe approach, the "gold standard" for lesions in the cerebellopontine angle. On the other hand, in some basal tumors, e.g., chordomas and chondrosarcomas, the approach has to be selected individually and must always be tailored to the characteristics of the particular tumor, its location, and the patient's expectations. The expertise of the surgeon is not reflected in his or her ability to perform the most complex approaches but in the ability to select the approach that affords both removal of the tumor and preservation of patient's neurological function and quality of life.