Vascular complications of vestibular schwannoma surgery: a comparison of the suboccipital retrosigmoid and translabyrinthine approaches

Unexpected Complications Following Accidental Petrosal Vein Damage during Standard Retrosigmoid Surgery for a Large Vestibular Schwannoma: Introspection and Lessons Learned

We present the case of a patient with a vestibular schwannoma (VS) who developed vascular complications following surgery and discuss the potential mechanisms. Additionally, we systematically searched the literature to identify citations on vascular and brain stem complications following VS surgery. We excluded the articles related to facial and vestibulocochlear nerve-related complications and other complications, such as headache, tinnitus, and ataxia. We also excluded the articles related to recurrent vestibular schwannoma because our article focuses on primary VS surgery-related complications due to vascular injury. We have clearly come a long way in managing vestibular schwannoma (VS) surgery over the past century. In the early twentieth century, VS surgery entailed high morbidity and mortality. The principles of microneurosurgery have improved the outcomes of surgery on VSs to a great extent. The current concept in modern VS surgery is maximal safe resection with minimal complications and minimal cranial nerve deficits. The management of VS has undergone a paradigm shift from reducing mortality to facial nerve preservation and the preservation of hearing. Surgery of the cerebellopontine (CP) angle requires a unique skill set and is a craft in that any iatrogenic damage can have devastating results on the neurovascular structures and brain stem in the vicinity. As with other neurosurgical procedures, the goal of VS surgery is to minimize complications, but complications are always possible, from the positioning of the patient under general anaesthesia to complications during the various steps of VS surgery. In spite of advancements in surgical techniques and better illumination provided by modern high-end microscopes, the surgical removal of large and giant vestibular schwannomas with good preservation of facial nerve function continues to be one of the most challenging operations in modern neurosurgery. The complexity of operating on the vestibular schwannoma is attributable not only to the difficult anatomy in the CP angle but also to the presence of multiple vital neurovascular structures and the brain stem in the vicinity. The various complications arising out of surgery for vestibular schwannomas range from one or more cranial nerve deficits to life-endangering complications associated with vascular and/or brain stem damage. The senior author, who has a personal experience with consecutively operating on 835 such cases of large and giant vestibular schwannoma, describes the clinical course following petrosal vein damage to a patient who underwent a standard retrosigmoid operation for a large vestibular schwannoma. We retrospectively analyse the critical management issues that could have reduced the unexpected morbidity resulting in a prolonged hospital stay.

Prevalence and patterns of cerebral venous sinus thrombosis following vestibular schwannoma surgery: a systematic review and meta-analysis

PURPOSE

Cerebral venous sinus thrombosis (CVST) is a potentially serious complication following surgical treatment of vestibular schwannoma, a benign tumor originating from Schwann cells of the vestibulocochlear nerve. This study aimed to determine the prevalence of CVST following surgical treatment of vestibular schwannoma and the factors contributing to its occurrence.

METHOD

Two independent researchers searched the global databases of PubMed, Web of Science, Scopus, and the Cochrane Library up to September 01, 2023. We employed a random-effects model for data analysis. Heterogeneity was evaluated using the I2 test. To assess the quality of the studies meeting our inclusion criteria, we employed the Joanna Briggs Institute Critical Appraisal Checklist.

RESULTS

We included 23 articles in this meta-analysis. The pooled prevalence of CVST after vestibular schwannoma surgery was 6.4% (95%CI 3.4-11.5%). The pooled prevalence of CVST following the retrosigmoid (RS), translabyrinthine (TL), and middle cranial fossa (MCF) approaches was 4.8% (95%CI 2.0-11.0%), 9.6% (95%CI 4.3-20.3%) and 9.9% (95%CI 1.6-42.2%), respectively, revealing a significant difference between the TL and the RS approaches (Odds ratio = 2.10, 95%CI 1.45-3.04, P < 0.001). The sigmoid sinus exhibited the highest post-operative thrombosis rate (7.9%), surpassing the transverse sinus (3.7%) and involvement of both sigmoid and transverse sinuses (1.6%), respectively. No significant associations were found with demographic or surgical factors.

CONCLUSION

In the current meta-analysis, we identified a 6.4% CVST prevalence following vestibular schwannoma surgery, with varying rates depending on the surgical approach. No significant associations with patient or surgical factors were found, emphasizing the need for heightened clinical vigilance and further research in this context.

TRAIL REGISTRATION

PROSPERO ID: CRD42023453513.

A novel theory for rapid localization of the transverse-sigmoid sinus junction and "keyhole" in the retrosigmoid keyhole approach: micro-anatomical study, technique nuances, and clinical application

To determine a rapid and accurate method for locating the keypoint and "keyhole" in the suboccipital retrosigmoid keyhole approach. (1) Twelve adult skull specimens were selected to locate the anatomical landmarks on the external surface of the skull.The line between the infraorbital margin and superior margin of the external acoustic meatus was named the baseline. A coordinate system was established using the baseline and its perpendicular line through the top point of diagastric groove.The perpendicular distance (x), and the horizontal distance (y) between the central point of the "keyhole" and the top point of the digastric groove in that coordinate system were measured. The method was applied to fresh cadaveric specimens and 53 clinical cases to evaluate its application value. (1) x and y were 14.20 ± 2.63 mm and 6.54 ± 1.83 mm, respectively (left) and 14.95 ± 2.53 mm and 6.65 ± 1.61 mm, respectively (right). There was no significant difference between the left and right sides of the skull (P > 0.05). (2) The operative area was satisfactorily exposed in the fresh cadaveric specimens, and no venous sinus injury was observed. (3) In clinical practice, drilling did not cause injury to venous sinuses, the mean diameter of the bone windows was 2.0-2.5 cm, the mean craniotomy time was 26.01 ± 3.46 min, and the transverse and sigmoid sinuses of 47 patients were well-exposed. We propose a "one point, two lines, and two distances" for "keyhole" localization theory, that is we use the baseline between the infraorbital margin and superior margin of the external acoustic meatus and the perpendicular line to the baseline through the top point of the digastric groove to establish a coordinate system. And the drilling point was 14.0 mm above and 6.5 mm behind the top point of the digastric groove in the coordinate system.

Superior petrosal vein sacrifice in translabyrinthine approach for resection of vestibule schwannoma

PURPOSE

The aim of this study was to evaluate the safety and surgical outcome of superior petrosal vein (SPV, Dandy's vein) sacrifice in translabyrinthine approach (TLA) for resection of vestibule schwannoma (VS) as compared with SPV preservation, with further investigation of preoperational factors associated with the implement of SPV sacrifice.

METHODS

The authors prospectively collected data from patients surgically treated for VS through TLA between June 2021 and April 2022 at the Gruppo Otologico.

RESULTS

There were 30 and 49 patients in SPV sacrifice and preservation groups, respectively. SPV sacrifice group had significantly larger tumor size (2.46 vs. 1.40 cm), less percentage of solid tumor (26.7% vs. 83.7%), higher incidence of brainstem compression (80% vs. 26.5%), and higher percentage of facial numbness (20.0% vs. 4.1%) than SPV preservation group. Gross total resection (GTR) rates were 73.3% after SPV sacrifice and 87.8% after SPV preservation. Facial nerve preservation rates were similar. No complication related with SPV sacrifice was observed. Logistic regression analysis showed tumor size and complete solid consistency as significant risk factors associated with SPV sacrifice. ROC curve further demonstrated tumor size as a fair predictor (AUC = 0.833), with optimum cutoff value of 1.68 cm.

CONCLUSION

SPV sacrifice via TLA as needed is a safe and effective maneuver for removal of relatively large VS. Tumor size and consistency can be used as a guidance in preoperational decision-making, with cutoff value of 1.68 cm and cystic formation as predictive indicators.

Translabyrinthine Craniotomy Is Associated with Higher Risk of Asymptomatic Dural Venous Sinus Thrombosis in Vestibular Schwannoma Resection

OBJECTIVE

Characterize the incidence, risk factors, and patient outcomes of dural venous sinus thrombosis identified on postoperative imaging after retrosigmoid or translabyrinthine craniotomy for vestibular schwannoma resection.

STUDY DESIGN

Retrospective cohort study.

SETTING

Single tertiary academic referral center.

PATIENTS

Eighty-one patients 19 to 82 years of age with vestibular schwannomas, 58% female.

INTERVENTIONS

Retrosigmoid or translabyrinthine craniotomy with postoperative magnetic resonance imaging/magnetic resonance venography.

MAIN OUTCOME MEASURES

Association between operative approach, age, sex, body mass index, tumor size, dominant sinus, operative time, laterality, and perioperative cerebrospinal fluid (CSF) leaks with rate of thrombosis.

RESULTS

Translabyrinthine craniotomy was associated with the highest relative risk of thrombosis (odds ratios [OR] = 19.82, 95% confidence interval [CI] = 1.75-224, p = 0.007), followed by male sex (OR = 5.53, 95% CI = 1.63-18.8, p = 0.035). Other patient and demographic risk factors were not associated with increased rates of dural venous thrombosis, nor was there an association with postoperative CSF leak. 81% (25/31) of thrombi had resolved within 3 years of surgery.

CONCLUSIONS

Translabyrinthine approach and male sex most strongly predicted postoperative dural venous thrombosis after postauricular craniotomy for vestibular schwannoma resection.

PROFESSIONAL PRACTICE GAP AND EDUCATIONAL NEED

Better understanding of risk factors and management of dural venous thrombosis after vestibular schwannoma surgery.

LEARNING OBJECTIVE

Characterize clinically significant risk factors for dural venous thrombosis in vestibular schwannoma surgery.

DESIRED RESULT

Identification of patient and operative risk factors for dural venous thrombosis.

LEVEL OF EVIDENCE

III.

INDICATE IRB OR IACUC

Exempt.

Generating Operative Workflows for Vestibular Schwannoma Resection: A Two-Stage Delphi's Consensus in Collaboration with the British Skull Base Society. Part 1: The Retrosigmoid Approach

Objective  An operative workflow systematically compartmentalizes operations into hierarchal components of phases, steps, instrument, technique errors, and event errors. Operative workflow provides a foundation for education, training, and understanding of surgical variation. In this Part 1, we present a codified operative workflow for the retrosigmoid approach to vestibular schwannoma resection. Methods  A mixed-method consensus process of literature review, small-group Delphi's consensus, followed by a national Delphi's consensus, was performed in collaboration with British Skull Base Society (BSBS). Each Delphi's round was repeated until data saturation and over 90% consensus was reached. Results  Eighteen consultant skull base surgeons (10 neurosurgeons and 8 ENT [ear, nose, and throat]) with median 17.9 years of experience (interquartile range: 17.5 years) of independent practice participated. There was a 100% response rate across both Delphi's rounds. The operative workflow for the retrosigmoid approach contained three phases and 40 unique steps as follows: phase 1, approach and exposure; phase 2, tumor debulking and excision; phase 3, closure. For the retrosigmoid approach, technique, and event error for each operative step was also described. Conclusion  We present Part 1 of a national, multicenter, consensus-derived, codified operative workflow for the retrosigmoid approach to vestibular schwannomas that encompasses phases, steps, instruments, technique errors, and event errors. The codified retrosigmoid approach presented in this manuscript can serve as foundational research for future work, such as operative workflow analysis or neurosurgical simulation and education.

Phenotypical variability of the sigmoid sinus in translabyrinthine and retrosigmoid surgeries

INTRODUCTION

We hypothesized that the cranial phenotype influences the shape of the posterior cranial fossa and the relative position of the sigmoid sinus.

MATERIALS AND METHODS

The topography of the sigmoid sinus was studied on 26 magnetic resonance venograms and 35 embalmed cadavers by morphometric analysis, dissection, and photo modeling techniques.

RESULTS

The data show that the transverse diameter of the posterior cranial fossa correlates positively with the laterolateral diameter of the skull. The majority of cases with the low-anterior position of the sigmoid sinus were recorded in the brachycephalic group (82%), while the high-posterior localization of the sigmoid sinus was typical for the dolichocephalic patients (63%). The results of the ANOVA test confirm the significance of differences.

CONCLUSIONS

The shape of the skull reflects the morphology of the posterior cranial fossa and influences the topographic characteristics of the sigmoid sinus that must be considered in the selection of surgical approach to the inner ear and pontocerebellar angle.

Functional Outcomes and Postoperative Cerebral Venous Sinus Thrombosis after Translabyrinthine Approach for Vestibular Schwannoma Resection: A Radiographic Demonstration of Anatomic Predictors

Introduction While regarded as an effective surgical approach to vestibular schwannoma (VS) resection, the translabyrinthine (TL) approach is not without complications. It has been postulated that postoperative cerebral venous sinus thrombosis (pCVST) may occur as a result of injury and manipulation during surgery. Our objective was to identify radiologic, surgical, and patient-specific risk factors that may be associated with pCVST.

Methods The Institutional Review Board (IRB) approval was obtained and the medical records of adult patients with VS who underwent TL craniectomy at University Hospitals Cleveland Medical Center between 2009 and 2019 were reviewed. Demographic data, radiographic measurements, and tumor characteristics were collected. Outcomes assessed included pCVST and the modified Rankin score (mRS).

Results Sixty-one patients ultimately met inclusion criteria for the study. Ten patients demonstrated radiographic evidence of thrombus. Patients who developed pCVST demonstrated shorter internal auditory canal (IAC) to sinus distance (mean: 22.5 vs. 25.0 mm, p = 0.044) and significantly smaller petrous angles (mean: 26.3 vs. 32.7 degrees, p = 0.0045). Patients with good mRS scores (<3) appeared also to have higher mean petrous angles (32.5 vs. 26.8, p = 0.016). Koos' grading and tumor size, in our study, were not associated with thrombosis.

Conclusion More acute petrous angle and shorter IAC to sinus distance are objective anatomic variables associated with pCVST in TL surgical approaches.

Cerebrovascular Complications of Vestibular Schwannoma Surgery

Objective Cerebrovascular complications (CVC) are rare consequences of vestibular schwannoma (VS) surgery. Our objective was to assess incidences of findings suggestive of postoperative CVC in a large single surgeon cohort, as well as potential risk factors, and implications.

Study Design A cohort of 591 patients was retrospectively reviewed. Postoperative magnetic resonance images were screened for findings suggestive of stroke, T2 hyperintensity in the cerebellopontine angle structures or new encephalomalacia. Clinical records were queried for findings consistent with postoperative CVC.

Results In total, 61 patients had radiographic findings consistent with possible postoperative CVC (10%); of them, eight had documented intraoperative vascular injury (1.4%), and four had postoperative clinical exam changes indicative of CVC (0.7%). Clinically manifest intraoperative vascular injuries occurred in four patients and involved the petrosal venous complex (n = 3, 5%) or anterior inferior cerebellar artery (n = 1, 2%); clinical deficits included hemiparesis (n = 1, 2%), facial anesthesia (n = 2, 4%), dysphagia (n = 2, 2%), and unfavorable facial nerve function in two (50%). Three out of four patients in this group required out-of-home placement (75%). Clinical CVCs (n = 4) were not significantly associated with tumor size, tumor cyst, gross total resection, or length of stay. Patients with clinical CVC were significantly more likely to require posthospitalization rehabilitation (19 vs. 75%, p = 0.02; 14 vs. 100%, p = 0.0002).

Conclusion Although radiographic findings suggestive of CVC were unexpectedly common in this cohort, intraoperative vascular injury and postoperative clinical CVC were exceedingly rare. The association between unfavorable facial nerve outcome and clinical CVC is likely a marker for more difficult operations, predisposing to higher risk of complications.

Surgical Effects of Resecting Skull Base Tumors Using Pre-operative Multimodal Image Fusion Technology: A Retrospective Study

Objectives

To analyze the surgical effects of resecting skull base tumors using multimodal three-dimensional (3D) image fusion technology in the neurosurgery department and present some typical cases.

Methods

From October 2019 to October 2021, we included 47 consecutive patients with skull base tumors in the Neurosurgery Department at Zhuhai People's Hospital in this study. Pre-operative head computed tomography and magnetic resonance imaging data acquisition was performed using the GE AW workstation software for registration fusion, image fusion, and 3D reconstruction. The surgical approach and surgical plan were designed based on the multimodal 3D image, and the resection rate, complication rate, and operative time of the surgery using the multimodal image fusion technique were analyzed.

Results

The reconstructed multimodal 3D images precisely demonstrated the size, location, and shape of the tumor along with the anatomical relationship between the tumor and surrounding structures, which is consistent with the intraoperative findings. Among 47 patients, 39 patients (78.7%) underwent total resection, 5 (14.9%) underwent subtotal resection, and 3 (6.4%) underwent partial resection. The mean operative time was 4.42 ± 1.32 h. No patient died during the inpatient period. Post-operative complications included 6 cases of cerebrospinal fluid leakage (14.9%), 3 cases of intracranial infection (6.4%), 6 cases of facial paralysis (12.8%), 2 cases of dysphagia (4.3%), and 1 case of diplopia (2.1%), all of which were improved after symptomatic treatment. The application value of pre-operative 3D image fusion technology was evaluated as outstanding in 40 cases (85.1%) and valuable in 7 cases (14.9%).

Conclusions

Pre-operative multimodal image fusion technology can provide valuable visual information in skull base tumor surgery and help neurosurgeons design the surgical incision, choose a more rational surgical approach, and precisely resect the tumor. The multimodal image fusion technique should be strongly recommended for skull base tumor surgery.

The combined TL-RS approach: Advantages and disadvantages of working 360 degrees around the sigmoid sinus

Abstract Objective: To highlight the advantages and disadvantages of the combined translabyrinthine (TL) and classic retrosigmoid (RS) approach. Design: Retrospective chart review. Setting: National Tertiary Referral Center for skull base pathology. Participants: Twenty-two patients with very large cerebellopontine angle tumors were resected using the combined TL-RS approach. Main outcome measures: Preoperative patient characteristics, including age, sex, and hearing loss. Tumor characteristics, pathology, and size. Intraoperative outcome: Tumor removal. Postoperative outcomes included facial nerve function, residual tumor growth, and neurological deficits. Results: Thirteen patients had schwannoma, eight had meningioma, and one had both. The mean age was 47 years, mean tumor size was 39 × 32 × 35 mm (anterior-posterior, medial-lateral, craniocaudal), and mean follow-up period was 80 months. Tumor control was achieved in 13 patients (59%), and nine (41%) had residual tumor growth that required additional treatment. Seventeen patients (77%) had postoperative HouseBrackmann (HB) facial nerve function grade 12, one had HB grade 3, one HB V, and three HB VI. Conclusion: Combining TL and RS approach may be helpful in safely removing large meningiomas and schwannomas in selected cases. This valuable technique should be considered when sufficient exposure cannot be achieved with the TL or RS approach alone.

Blood supply to the corticospinal tract: A pictorial review with application to cranial surgery and stroke

The corticospinal tract (CST) is the main neural pathway responsible for conducting voluntary motor function in the central nervous system. The CST condenses into fiber bundles as it descends from the frontoparietal cortex, traveling down to terminate at the anterior horn of the spinal cord. The CST is at risk of injury from vascular insult from strokes and during neurosurgical procedures. The aim of this article is to identify and describe the vasculature associated with the CST from the cortex to the medulla. Dissection of cadaveric specimens was carried out in a manner, which exposed and preserved the fiber tracts of the CST, as well as the arterial systems that supply them. At the level of the motor cortex, the CST is supplied by terminal branches of the anterior cerebral artery and middle cerebral artery. The white matter tracts of the corona radiata and internal capsule are supplied by small perforators including the lenticulostriate arteries and branches of the anterior choroidal artery. In the brainstem, the CST is supplied by anterior perforating branches from the basilar and vertebral arteries. The caudal portions of the CST in the medulla are supplied by the anterior spinal artery, which branches from the vertebral arteries. The non-anastomotic nature of the vessel systems of the CST highlights the importance of their preservation during neurosurgical procedures. Anatomical knowledge of the CST is paramount to clinical diagnosis and treatment of heterogeneity of neurodegenerative, neuroinflammatory, cerebrovascular, and skull base tumors.

Pulmonary Embolism and Sigmoid Sinus Thrombosis After Translabyrinthine Vestibular Schwannoma Resection: A Retrospective Case Series

OBJECTIVE

To describe the presentation and treatment of patients developing pulmonary embolism following translabyrinthine approach for vestibular schwannoma resection.

METHODS

This was a retrospective case series of patients at 2 academic tertiary medical centers who developed symptomatic pulmonary embolism post-operatively following translabyrinthine approach for vestibular schwannoma resection and were found to have evidence of sigmoid sinus thrombosis.

RESULTS

Three patients were identified to have post-operative pulmonary emboli after translabyrinthine approach for vestibular schwannoma resection with sigmoid sinus or internal jugular vein clots in the absence of lower extremity deep vein thrombosis. Caprini scores for these patients were 5 or lower. All patients underwent CT pulmonary angiography and were confirmed to have pulmonary emboli. Two were promptly anticoagulated with heparin drips and transitioned to long-term oral anticoagulation therapy and 1 had delayed anticoagulation. None of these patients suffered from intracranial hemorrhage post-operatively.

CONCLUSIONS

Patients undergoing translabyrinthine approach for vestibular schwannoma can develop pulmonary embolism from sigmoid sinus entry or thrombosis. No clear guidelines exist for the management of this complication in the setting of recent craniotomy and the risk of intracranial hemorrhage must be considered prior to initiating anticoagulation.

Peritumoral Edema Is Associated With Postoperative Hemorrhage and Reoperation Following Vestibular Schwannoma Surgery

Background: Postoperative hemorrhage (POH) is a severe complication following vestibular schwannoma surgery that may require surgical treatment. The purpose of our study is to identify risk factors associated with POH and reoperation following the resection of vestibular schwannoma.

Methods: We retrospectively recruited 452 vestibular schwannoma patients treated with retrosigmoid approach. The primary outcome was POH, and the secondary outcome was reoperation for POH. Clinical and radiographic data were compared by performing univariate analysis and logistic regression analysis.

Results: Among the 452 patients, 37 patients (8.2%) presented with POH and14 patients (3.1%) required reoperation within a 30-day hospitalization period. The univariate analysis showed that peritumoral edema, tumor diameter >30 mm, severe postoperative hypertension, and length of hospital stay were associated with POH and reoperation for POH. Logistic regression analysis showed that peritumoral edema [odds ratio (OR) 4.042, 95% confident interval (CI) 1.830–8.926, P = 0.001] and tumor diameter >30 mm (OR 3.192, 95% CI 1.421–7.168, P = 0.005) were independent predictive factors for POH. Peritumoral edema (OR 7.071, 95% CI 2.342–21.356, P = 0.001) was an independent predictive factor for reoperation by using logistic regression analysis. Further analysis revealed that larger tumor and incomplete tumor resection were both associated with a higher incidence of peritumoral edema.

Conclusion: Peritumoral edema and tumor size are independent risk factors for POH following vestibular schwannoma surgery. And larger hematoma occurs more commonly in tumors with peritumoral edema which may require reoperation. Tumor size and extent of tumor resection are associated with peritumoral edema. Close attention should be paid to high-risk patients especially for those who presented with severe postoperative hypertension.

Hypercoagulability in Vestibular Schwannoma Surgery

OBJECTIVE

Patients with vestibular schwannoma who harbor a genetic predisposition for venous thromboembolism require special consideration when determining optimal therapeutic management. The primary objective of the current study was to provide recommendations on treatment of hypercoagulable patients with vestibular schwannoma through a case series and review of the literature.

PATIENTS

Two patients who underwent resection of vestibular schwannomas.

INTERVENTIONS

Surgical resection and diagnostic testing.

MAIN OUTCOME MEASURES

Postoperative venous thromboses.

RESULTS

One patient who underwent resection of vestibular schwannoma and suffered several postoperative thrombotic complications consistent with a clinical thrombophilia. One patient with known Factor V Leiden deficiency who underwent resection of vestibular schwannoma followed by postoperative chemoprophylaxis with a direct factor Xa inhibitor and experienced an uneventful postoperative course.

CONCLUSIONS

In patients with a known propensity for venous thromboembolism, the skull base surgeon should consider nonsurgical management. If the patient undergoes surgical resection, we recommend careful effort to minimize trauma to the sigmoid sinus. In addition, the surgeon may consider retrosigmoid or middle fossa approaches. Best practice recommendations include the use of pneumatic compression devices, early ambulation, and consideration of postoperative prophylactic anticoagulation in patients with a known genetic predisposition.

Natural History of Untreated Transverse/Sigmoid Sinus Thrombosis Following Posterior Fossa Surgery: Case Series and Literature Review

BACKGROUND

Transverse or sigmoid sinus thrombosis occurs in 4% to 11% of patients following posterior fossa surgery. Anticoagulation has been the mainstay treatment, mostly based on extrapolation from the literature on spontaneous sinus thrombosis.

OBJECTIVE

To analyze the rate and associated complications of postoperative transverse/sigmoid sinus thrombosis for patients undergoing posterior fossa tumor resection. In this series, no antithrombotic therapy was initiated, and no postoperative treatment alterations were made following thrombosis diagnosis.

METHODS

Prospectively accrued cases from a single surgeon operating at a single academic center were retrospectively reviewed to determine the natural history of untreated transverse/sigmoid sinus thrombosis following posterior fossa surgery. Inclusion criteria were patients 18 yr or older undergoing resection of a posterior fossa tumor. A total of 538 patients were analyzed.

RESULTS

In all 26 out of 538 (4.8%) patients were diagnosed with transverse/sigmoid sinus thrombosis on routine postoperative imaging. Early postoperative complication rate was 38% in the sinus thrombosis group, as compared to 15% in the no-thrombosis group (P = .02). A significantly higher rate of pseudomeningocele, dysphagia requiring gastrostomy, and cerebellar stroke signs were noted in patients with postoperative sinus thrombosis. However, only 3 of the 26 patients (12%) with postoperative sinus occlusion suffered prolonged central nervous system complications.

CONCLUSION

Transverse/sigmoid sinus thrombosis following suboccipital craniectomy results in a higher rate of early complications; however, most of these complications resolve without anticoagulation. It may be reasonable, therefore, to manage these patients conservatively in order to avoid the risks associated with anticoagulation in the perioperative period.

Dural Venous Sinus Thrombosis after Vestibular Schwannoma Surgery: The Anticoagulation Dilemma

Introduction  Dural venous sinus thrombosis (DVST) is a relatively understudied complication of vestibular schwannoma (VS) surgery. Several studies have examined this topic; however, there is limited data on the incidence, clinical progression, and proper management of this patient population. Methods  A retrospective review was performed for patients undergoing surgery for VS at a single institution. All postoperative imaging was reviewed for incidence of DVST. Demographic data were collected including tumor and surgical characteristics along with postoperative course. Results  A total of 63 patients underwent resection of their VS. The incidence of DVST was 34.9%. The operative time was greater in the dural venous sinus thrombosis (DSVT) group, at an average of 6.69 hours versus 4.87 in the no DSVT cohort ( p  = 0.04). Tumor size was correlationally significant ( p  = 0.051) at 2.75 versus 2.12 cm greatest diameter. The translabyrinthine approach was most prevalent (68.2%). The side of the thrombosis was ipsilateral to the tumor and surgery in all patients. The sigmoid sinus was most commonly involved (95.5%). Of them, 85% patients had a codominant or thrombus contralateral to the dominant sinus. All patients were asymptomatic. No patients were treated with anticoagulation. Resolution of thrombus was seen in five (22.7%) of the patients on last follow-up imaging. There were no hemorrhagic complications. Conclusion  The overall incidence of DVST was (34.9%) of 63 patients who underwent VS surgery. All patients were asymptomatic and none were treated with anticoagulation. In our study, continuing to observe asymptomatic patients did not lead to any adverse events.

Incidence and Risk Factors for Sigmoid Venous Thrombosis Following CPA Tumor Resection

OBJECTIVE

Our primary aim was to determine the incidence of sigmoid venous thrombosis (SVT) and determine risks factors and sequelae of SVT following cerebellopontine angle tumor resection.

STUDY DESIGN

Retrospective cohort study.

SETTING

Academic tertiary care hospital.

PATIENTS

Patients over 18 years of age who underwent resection of cerebellopontine angle meningioma or vestibular schwannoma from January 2005 to April 2016 who had postoperative magnetic resonance imaging.

INTERVENTION(S)

Diagnostic.

MAIN OUTCOME MEASURE(S)

Incidence of postoperative sigmoid venous thrombosis (SVT) from official radiology reports was compared with retrospective imaging review by our institutional neuroradiologists. Data collected included age, length of stay, body mass index, surgical approach, and postoperative complications.

RESULTS

A total of 127 patients were identified. Official radiology reads significantly underreported the incidence of postoperative SVT compared with retrospective review by our institutional neuroradiologist for patients who underwent routine postoperative imaging (n = 4 [3.1%] versus n = 22 [17.3%]; p < 0.001). There was a statistical trend toward increased risk for thrombosis in patients undergoing translabyrinthine and staged resection that did not reach significance (p = 0.068). Cerebrospinal fluid (CSF) leak incidence in patients with thrombosis was significantly increased (n = 9 [37.5%] versus n = 13 [12.6%]; p = 0.007). When controlling for approach, the presence of thrombus was associated with a more then three-fold increase in odds of CSF leak (OR = 3.28, 95% CI: 1.12-9.48, p = 0.030). There was no correlation between SVT and age (p = 0.788), body mass index (p = 0.686), length of stay (p = 0.733), preoperative tumor size (p = 0.555), or increased postoperative ICP (p = 0.645). Only one patient was symptomatic from sigmoid thrombosis compared with 21 who were not.

CONCLUSION

Incidence of SVT is significantly underreported and may predispose patients to increase risk for CSF leak. Staged and translabyrinthine approaches demonstrate an increased trend toward thrombosis risk. Our findings suggest it may not be necessary to treat asymptomatic SVT.

Surgery of the lateral skull base: a 50-year endeavour

Disregarding the widely used division of skull base into anterior and lateral, since the skull base should be conceived as a single anatomic structure, it was to our convenience to group all those approaches that run from the antero-lateral, pure lateral and postero-lateral side of the skull base as “Surgery of the lateral skull base”. “50 years of endeavour” points to the great effort which has been made over the last decades, when more and more difficult surgeries were performed by reducing morbidity. The principle of lateral skull base surgery, “remove skull base bone to approach the base itself and the adjacent sites of the endo-esocranium”, was then combined with function preservation and with tailoring surgery to the pathology. The concept that histology dictates the extent of resection, balancing the intrinsic morbidity of each approach was the object of the first section of the present report. The main surgical approaches were described in the second section and were conceived not as a step-by-step description of technique, but as the highlighthening of the surgical principles. The third section was centered on open issues related to the tumor and its treatment. The topic of vestibular schwannoma was investigated with the current debate on observation, hearing preservation surgery, hearing rehabilitation, radiotherapy and the recent efforts to detect biological markers able to predict tumor growth. Jugular foramen paragangliomas were treated in the frame of radical or partial surgery, radiotherapy, partial “tailored” surgery and observation. Surgery on meningioma was debated from the point of view of the neurosurgeon and of the otologist. Endolymphatic sac tumors and malignant tumors of the external auditory canal were also treated, as well as chordomas, chondrosarcomas and petrous bone cholesteatomas. Finally, the fourth section focused on free-choice topics which were assigned to aknowledged experts. The aim of this work was attempting to report the state of the art of the lateral skull base surgery after 50 years of hard work and, above all, to raise questions on those issues which still need an answer, as to allow progress in knowledge through sharing of various experiences. At the end of the reading, if more doubts remain rather than certainties, the aim of this work will probably be achieved.

Complications in translabyrinthine surgery of vestibular schwannoma

OBJECTIVE

To evaluate the risk of complications associated with tumor size and patient's age in translabyrinthine vestibular schwannoma surgery.

METHODS

700 patients with vestibular schwannoma primarily underwent translabyrinthine surgery between 1988 and 2014. Pre- and postoperative data were collected in a database and incidence of the postoperative complications cerebrospinal fluid leakage, meningitis, intracranial hemorrhage (ICH), facial nerve function and mortality were assessed and related to the tumor size and patient's age and retrospectively evaluated.

RESULTS

The tumor size significantly influenced the incidence of ICH and facial nerve dysfunction whereas age was correlated to facial nerve outcome.

CONCLUSIONS

The translabyrinthine approach is a safe surgical procedure with relatively low risks of complications. The tumor size was significantly associated with a higher risk of ICH and facial nerve dysfunction whereas age only influenced the facial nerve outcome.

Microvascular Brainstem Ischemia After Vestibular Schwannoma Surgery: A Clinical and Microanatomic Study

OBJECTIVE

To identify a potential microvascular etiology in patients who underwent vestibular schwannoma surgery (VSS) complicated by postoperative microvascular brainstem ischemia.

METHODS

Charts were retrospectively reviewed of all patients who had an MRI within 14 days of VSS in years 2005-2016. Patient characteristics, preoperative and postoperative imaging features, clinical course and potential predictors of brainstem ischemia were recorded. Cadaveric dissections of 4 cerebellopontine angle (CPA) cisterns with focus on the anterior inferior cerebellar artery (AICA) microvascular were also performed to identify candidate vessels and potential etiology.

RESULTS

Fifty-four of 258 patients had an MRI within 14 days of VSS. Retrosigmoid approach was used in 61.1% of patients, translabyrinthine approach in 25.9%, and middle fossa approach in 13.0%. Four patients (7.4%) had acute microvascular ischemia involving the middle cerebellar peduncle (MCP) adjacent to the cranial nerve (CN) VII-VIII complex demonstrated on postoperative MRI. A statistically significant association was found between the translabyrinthine approach and acute brainstem ischemia (odds ratio, 10.6; 95% confidence interval, 1.004-112.7). Dissection of CPAs revealed 10-20 perforating arteries per specimen originating from the lateral pontine and the flocculopeduncular segments of the AICA. Most microvessels travelled in retrograde fashion along the anteroinferior surface of the CN VII-VIII complex to perforate the cisternal surface of the MCP. No patient had residual or delayed neurologic deficits related to brainstem ischemia at final follow-up.

CONCLUSIONS

While effort should be made to preserve perforating vessels, microvascular brainstem ischemia is often asymptomatic and did not lead to permanent neurologic deficits in our series.

The pathogenesis of delayed epidural hematoma after posterior fossa surgery

The purpose of this study was to analyze the pathogenesis of delayed epidural hematoma (EDH) after posterior fossa surgery. Non-traumatic, non-arterial origin delayed EDH after posterior fossa surgery is extremely rare. Moreover, the pathogenesis of its supratentorial extension is obscure. Between April 1997 and June 2016, over 3300 patients underwent microvascular decompression (MVD) for neurovascular compression syndrome. The medical chart of four patients with delayed EDH were retrospectively reviewed. The median time from MVD to re-CT scan was 58 h (range, 33-100). All patients underwent hematoma evacuations. Intraoperative findings during hematoma evacuation revealed only an oozing hemorrhage from the transverse sinus with no definitive bleeding focus. The patients spent a median of 21.5 days (range, 11-39) at the hospital. At the last follow-up, all patients had fully recovered without significant neurological deficits and exhibited complete relief or minimal symptoms from hemifacial spasm (HFS). Postoperative uncontrolled bleeding from the dural venous sinus can sometimes cause an insidious-onset or delayed posterior fossa EDH.

Initial experience with a robotically operated video optical telescopic-microscope in cranial neurosurgery: feasibility, safety, and clinical applications

OBJECTIVE

The move toward better, more effective optical visualization in the field of neurosurgery has been a focus of technological innovation. In this study, the authors’ objectives are to describe the feasibility and safety of a new robotic optical platform, namely, the robotically operated video optical telescopic-microscope (ROVOT-m), in cranial microsurgical applications.

METHODS

A prospective database comprising patients who underwent a cranial procedure between April 2015 and September 2016 was queried, and the first 200 patients who met the inclusion criteria were selected as the cohort for a retrospective chart review. Only adults who underwent microsurgical procedures in which the ROVOT-m was used were considered for the study. Preoperative, intraoperative, and postoperative data were retrieved from electronic medical records. The authors address the feasibility and safety of the ROVOT-m by studying various intraoperative variables and by reporting perioperative morbidity and mortality, respectively. To assess the learning curve, cranial procedures were categorized into 6 progressively increasing complexity groups. The main categories of pathology were I) intracerebral hemorrhages (ICHs); II) intraaxial tumors involving noneloquent regions or noncomplex extraaxial tumors; III) intraaxial tumors involving eloquent regions; IV) skull base pathologies; V) intraventricular lesions; and VI) cerebrovascular lesions. In addition, the entire cohort was evenly divided into early and late cohorts.

RESULTS

The patient cohort comprised 104 female (52%) and 96 male (48%) patients with a mean age of 56.7 years. The most common pathological entities encountered were neoplastic lesions (153, 76.5%), followed by ICH (20, 10%). The distribution of cases by complexity categories was 11.5%, 36.5%, 22%, 20%, 3.5%, and 6.5% for Categories I, II, II, IV, V, and VI, respectively. In all 200 cases, the surgical goal was achieved without the need for intraoperative conversion. Overall, the authors encountered 3 (1.5%) major neurological morbidities and 6 (3%) 30-day mortalities. Four of the 6 deaths were in the ICH group, resulting in a 1% mortality rate for the remainder of the cohort when excluding these patients. None of the intraoperative complications were considered to be attributable to the visualization provided by the ROVOT-m. When comparing the early and late cohorts, the authors noticed an increase in the proportion of higher-complexity surgeries (Categories IV–VI), from 23% in the early cohort, to 37% in the late cohort (p = 0.030). In addition, a significant reduction in operating room setup time was demonstrated (p < 0.01).

CONCLUSIONS

The feasibility and safety of the ROVOT-m was demonstrated in a wide range of cranial microsurgical applications. The authors report a gradual increase in case complexity over time, representing an incremental acquisition of experience with this technology. A learning curve of both setup and execution phases should be anticipated by new adopters of the robot system. Further prospective studies are required to address the efficacy of ROVOT-m. This system may play a role in neurosurgery as an integrated platform that is applicable to a variety of cranial procedures.

Functional outcome and complications after the microsurgical removal of giant vestibular schwannomas via the retrosigmoid approach: a retrospective review of 16-year experience in a single hospital

BACKGROUND

Intracranial vestibular schwannoma still remain to be difficulty for its unique microsurgical technique and preservation of neuro-function, as well as reducing common complications that may arise in surgery.

METHODS

We consecutively enrolled 657 unilateral giant (>4 cm diameter) vestibular schwannoma patients treated in Huashan Hospital via the suboccipital retrosigmoid approach in the past 16 years. The extension of tumor removal, surgical mortality, facial nerve function, hearing, and the other main short and long-term complications were the studied parameters.

RESULTS

Gross total resection was performed in 556 patients (84.6%); near-total resection was achieved in 99 patients (15.1%). The mortality rate is 0.6%. The main short-term complications included 'new' deafness (47.6%), intracranial infection (7.6%), lower cranial nerve defects (7.5%) and pneumonia (6.2%). The facial nerve was preserved anatomically in 589 cases (89.7%). Good facial nerve functional outcome (House-Brackmann Grades I and II) postoperatively was achieved in 216 patients (32.9%). Other 308 cases (46.9%) were House-Brackmann grade III, and 133 patients (20.2%) were House-Brackmann grade IV-VI. Follow-up data were available for 566 of the 657 patients (86.1%). The common long-term complications were hearing loss (85.2%), facial paralysis (HB grade IV-VI, 24.4%) and facial numbness (15.7%).

CONCLUSIONS

Trends in the data lead the authors to suggest that the microsurgical technique, intraoperative nerve monitoring, and multidisciplinary cooperation, were the keys to improving prognostic outcomes in giant intracranial vestibular schwannoma patients.

Venous sinus compromise after pre-sigmoid, transpetrosal approach for skull base tumors: A study on the asymptomatic incidence and report of a rare dural arteriovenous fistula as symptomatic manifestation

The sigmoid sinus is routinely exposed and manipulated during pre-sigmoid, transpetrosal approaches to the skull base, but there is scant data available on the incidence of venous sinus compromise after surgery. We encountered a dural arteriovenous fistula as a result of sigmoid sinus occlusion and examined the incidence of venous sinus thrombosis or narrowing after transpetrosal surgeries. We performed a retrospective analysis of a series of patients treated by the senior surgeons (WCJ, MH, HJK), who underwent either a posterior petrosectomy or translabyrinthine approach for various skull base tumors. All available clinical and radiographic data were thoroughly examined in each patient to determine the post-operative fate of the venous sinuses. Of the 52 available patients, five patients were discovered post-operatively to have a narrowed or constricted sigmoid sinus ipsilateral to the surgery, whereas another five patients were diagnosed with asymptomatic sinus thrombosis either in the transverse or sigmoid or both. None of these patients experienced symptoms, nor were there any instance of ischemic or hemorrhagic complications. However, there was one additional patient who presented with pulsatile tinnitus 2years after surgery. His angiogram showed an occlusion of the ipsilateral sigmoid sinus and a posterior fossa dural arteriovenous fistula. A two-stage transvenous and transarterial embolization was successful in eliminating the fistula. Technical considerations to avoid sinus injuries during pre-sigmoid, transpetrosal surgery are discussed.

Complications and Management of Large Intracranial Vestibular Schwannomas Via the Retrosigmoid Approach

OBJECTIVE

To investigate the common complications from the microsurgical treatment of large intracranial vestibular schwannoma (VS) via suboccipital retrosigmoid approach and to propose strategies for minimizing such complications.

METHODS

We selected all patients with large unilateral VS from the collected database (1999-2013) who underwent microsurgical resection as their initial treatment for histopathologically confirmed VS. Tumors larger than 30 × 20 mm were defined as large.

RESULTS

A total of 1167 patients with VS were included. Gross total tumor resection was achieved in 1006 patients (86.2%). The mortality rate is 0.77%. The facial nerve was preserved anatomically in 1083 cases (92.8%), and the functional valuation of the facial nerve according to postoperative House-Brackmann scale showed 423 patients (36.2%) in grades I-II, 534 cases (45.8%) in grade III, and 210 patients (18.0%) in grade IV-VI. The main short-term postoperative complication included new hearing loss (American Institute of Otolaryngology-Head and Neck Surgery grade D) in 634 cases (54.3%), disequilibrium in 250 cases (21.4%), labial herpes in 127 cases (10.9%), meningitis in 115 (9.85%) and lower cranial nerve deficit in 77 cases (6.59%). Follow-up data were available for 978 of the 1167 patients (83.8%). Long-term complications include hearing loss (American Institute of Otolaryngology-Head and Neck Surgery grade D) (75.8%), permanent facial paralysis (11.9%), facial numbness (10.9%), tinnitus (2.96%), chronic headache (2.25%), and taste disturbance (1.43%).

CONCLUSIONS

The key factors for reducing surgical complications include careful assessment of the functions of acoustic and facial nerves as well as a thorough understanding of anatomy via the retrosigmoid approach before operation, skillful microsurgical technique, and monitoring of multiple cranial nerves during resection.

Cerebellopontine angle meningiomas: postoperative outcomes in a modern cohort

OBJECT

Tumors of the cerebellopontine angle (CPA) have always proven difficult for neurosurgeons to optimally manage. Studies investigating the natural history and treatment of vestibular schwannomas have dominated the literature in this regard. Distinguishing meningiomas from schwannomas in this location carries particular importance as each tumor type has certain prognostic and surgical considerations. In this study, the authors have characterized the outcomes of 34 patients surgically treated for CPA meningiomas and have investigated various factors that may affect postoperative neurological function.

METHODS

The medical records of patients with CPA meningiomas who underwent surgery from 2005 to 2013 at the Duke University Health System were reviewed. Various patient, clinical, and tumor data were gathered from the medical records including patient demographics, pre- and postoperative neurological examinations, duration of symptoms, procedural details, tumor pathology and size, and treatment characteristics. Differences in continuous variables were then analyzed using the Student t-test while categorical variables were evaluated using the chi-square test.

RESULTS

A total of 34 patients underwent surgical treatment for CPA meningiomas during the 8-year period. Jugular foramen invasion was seen in 17.6% of tumors, with nearly half (41.2%) extending into the internal acoustic canal. The most common presenting symptom was hearing loss (58.8%), followed by headache (52.9%) and facial numbness/pain (50.0%). The most common cranial nerve (CN) affected was CN X (11.8%), followed by CNs VI and VII (5.9%). Postoperatively, no patients experienced a decrease in hearing, with only 5.9% of patients experiencing facial nerve palsies. Patients with tumors larger than 3 cm had a significantly higher incidence of permanent CN deficits than those with smaller tumors (45.5% vs 5.9%, respectively; p = 0.011). Also, tumor extension into the jugular foramen was associated with the occurrence of lower CN deficits, none of which occurred in tumors without jugular foramen invasion. Internal acoustic canal tumor extension was not seen to be associated with postoperative complications or CN deficits.

CONCLUSIONS

Meningiomas of the CPA are challenging lesions to treat surgically. However, the risk of facial palsy and hearing loss is significantly lower when compared with vestibular schwannomas. Novel methods for preoperative differentiation are needed to appropriately counsel patients on surgical risks. Also, due to the significant potential for neurological deficits, further studies are needed to investigate the utility of radiotherapy for these lesions.

Complications of microsurgery of vestibular schwannoma

BACKGROUND

The aim of this study was to analyze complications of vestibular schwannoma (VS) microsurgery.

MATERIAL AND METHODS

A retrospective study was performed in 333 patients with unilateral vestibular schwannoma indicated for surgical treatment between January 1997 and December 2012. Postoperative complications were assessed immediately after VS surgery as well as during outpatient followup.

RESULTS

In all 333 patients microsurgical vestibular schwannoma (Koos grade 1: 12, grade 2: 34, grade 3: 62, and grade 4: 225) removal was performed. The main neurological complication was facial nerve dysfunction. The intermediate and poor function (HB III-VI) was observed in 124 cases (45%) immediately after surgery and in 104 cases (33%) on the last followup. We encountered disordered vestibular compensation in 13%, permanent trigeminal nerve dysfunction in 1%, and transient lower cranial nerves (IX-XI) deficit in 6%. Nonneurological complications included CSF leakage in 63% (lateral/medial variant: 99/1%), headache in 9%, and intracerebral hemorrhage in 5%. We did not encounter any case of meningitis.

CONCLUSIONS

Our study demonstrates that despite the benefits of advanced high-tech equipment, refined microsurgical instruments, and highly developed neuroimaging technologies, there are still various and significant complications associated with vestibular schwannomas microsurgery.

Contemporary surgical management of vestibular schwannomas: analysis of complications and lessons learned over the past decade

BACKGROUND

Despite advanced microsurgical techniques, more refined instrumentation, and expert team management, there is still a significant incidence of complications in vestibular schwannoma surgery.

OBJECTIVE

To analyze complications from the microsurgical treatment of vestibular schwannoma by an expert surgical team and to propose strategies for minimizing such complications.

METHODS

Surgical outcomes and complications were evaluated in a consecutive series of 410 unilateral vestibular schwannomas treated from 2000 to 2009. Clinical status and complications were assessed postoperatively (within 7 days) and at the time of follow-up (range, 1-116 months; mean, 32.7 months).

RESULTS

Follow-up data were available for 357 of the 410 patients (87.1%). Microsurgical tumor resection was performed through a retrosigmoid approach in 70.7% of cases. Thirty-three patients (8%) had intrameatal tumors and 204 (49.8%) had tumors that were <20 mm. Gross total resection was performed in 306 patients (74.6%). Hearing preservation surgery was attempted in 170 patients with tumors <20 mm, and good hearing was preserved in 74.1%. The main neurological complication was facial palsy (House-Brackmann grade III-VI), observed in 14% of patients (56 cases) postoperatively; however, 59% of them improved during the follow-up period. Other neurological complications were disequilibrium in 6.3%, facial numbness in 2.2%, and lower cranial nerve deficit in 0.5%. Nonneurological complications included cerebrospinal fluid leaks in 7.6%, wound infection in 2.2%, and meningitis in 1.7%.

CONCLUSION

Many of these complications are avoidable through further refinement of operative technique, and strategies for avoiding complications are proposed.

Surgery for vestibular schwannomas: a systematic review of complications by approach

Object

Various studies report outcomes of vestibular schwannoma (VS) surgery, but few studies have compared outcomes across the various approaches. The authors conducted a systematic review of the available data on VS surgery, comparing the different approaches and their associated complications.

Methods

MEDLINE searches were conducted to collect studies that reported information on patients undergoing VS surgery. The authors set inclusion criteria for such studies, including the availability of follow-up data for at least 3 months, inclusion of preoperative and postoperative audiometric data, intraoperative monitoring, and reporting of results using established and standardized metrics. Data were collected on hearing loss, facial nerve dysfunction, persistent postoperative headache, CSF leak, operative mortality, residual tumor, tumor recurrence, cranial nerve (CN) dysfunction involving nerves other than CN VII or VIII, and other neurological complications. The authors reviewed data from 35 studies pertaining to 5064 patients who had undergone VS surgery.

Results

The analyses for hearing loss and facial nerve dysfunction were stratified into the following tumor categories: intracanalicular (IC), size (extrameatal diameter) < 1.5 cm, size 1.5–3.0 cm, and size > 3.0 cm. The middle cranial fossa approach was found to be superior to the retrosigmoid approach for hearing preservation in patients with tumors < 1.5 cm (hearing loss in 43.6% vs 64.3%, p < 0.001). All other size categories showed no significant difference between middle cranial fossa and retrosigmoid approaches with respect to hearing loss. The retrosigmoid approach was associated with significantly less facial nerve dysfunction in patients with IC tumors than the middle cranial fossa method was; however, neither differed significantly from the translabyrinthine corridor (4%, 16.7%, 0%, respectively, p < 0.001). The middle cranial fossa approach differed significantly from the translabyrinthine approach for patients with tumors < 1.5 cm, whereas neither differed from the retrosigmoid approach (3.3%, 11.5%, and 7.2%, respectively, p = 0.001). The retrosigmoid approach involved less facial nerve dysfunction than the middle cranial fossa or translabyrinthine approaches for tumors 1.5–3.0 cm (6.1%, 17.3%, and 15.8%, respectively; p < 0.001). The retrosigmoid approach was also superior to the translabyrinthine approach for tumors > 3.0 cm (30.2% vs 42.5%, respectively, p < 0.001). Postoperative headache was significantly more likely after the retrosigmoid approach than after the translabyrinthine approach, but neither differed significantly from the middle cranial fossa approach (17.3%, 0%, and 8%, respectively; p < 0.001). The incidence of CSF leak was significantly greater after the retrosigmoid approach than after either the middle cranial fossa or translabyrinthine approaches (10.3%, 5.3%, 7.1%; p = 0.001). The incidences of residual tumor, mortality, major non-CN complications, residual tumor, tumor recurrence, and dysfunction of other cranial nerves were not significantly different across the approaches.

Conclusions

The middle cranial fossa approach seems safest for hearing preservation in patients with smaller tumors. Based on the data, the retrosigmoid approach seems to be the most versatile corridor for facial nerve preservation for most tumor sizes, but it is associated with a higher risk of postoperative pain and CSF fistula. The translabyrinthine approach is associated with complete hearing loss but may be useful for patients with large tumors and poor preoperative hearing.

Dural arteriovenous fistula following translabyrinthine resection of cerebellopontine angle tumors: report of two cases

We describe two cases of dural arteriovenous fistula (DAVF) developing in a delayed fashion after translabyrinthine resection of cerebellopontine angle tumors. Two patients in an academic tertiary referral center, a 46-year-old woman and a 67-year-old man, underwent translabyrinthine resection of a 2-cm left vestibular schwannoma and a 4-cm left petrous meningioma, respectively. Both patients subsequently developed DAVF, and in each case the diagnosis was delayed despite serial imaging follow-up. In one patient, cerebrospinal fluid diversion before DAVF was identified as the cause of her intracranial hypertension; the other patient was essentially asymptomatic but with a high risk of hemorrhage due to progression of cortical venous drainage. Endovascular treatment was effective but required multiple sessions due to residual or recurrent fistulas. Dural arteriovenous fistula is a rare complication of translabyrinthine skull base surgery. Diagnosis requires a high index of clinical suspicion and an understanding of subtle imaging findings that may be present on follow-up studies performed for tumor surveillance. Failure to recognize this complication may lead to misguided interventions for treatment of hydrocephalus and other complications, as well as ongoing risks related to venous hypertension and intracranial hemorrhage. As this condition is generally curable with neurointerventional and/or surgical methods, timely diagnosis and treatment are essential.

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.

The enlarged translabyrinthine and transapical extension type I approach for large vestibular schwannomas

To evaluate the results obtained by performing the enlarged translabyrinthine and transapical extension type I approaches for removal of large vestibular schwannomas and those with anterior extensions. An academic tertiary referral centre at Mumbai, India. Retrospective case review. 35 patients of vestibular schwannomas having size greater than 3 cm in extrameatal diameter with extension anterior to the internal auditory canal who underwent the enlarged translabyrinthine or transapical extension type I approach and with a minimum follow up of 1 year are considered. Other subjects who underwent translabyrinthine approach but did not fulfill the above criteria were excluded. Tumor was removed completely in 34 subjects (97.1%). Anatomic interruption of facial nerve occured in 4 cases (11.4%); 3 subjects underwent end to end anastomosis and 1 subject required a cable graft, these were done during the primary procedure itself. At 1 year follow up 28 subjects (80%) had good facial function (Grade I and II, House Brackmann Grading). Postoperative cerebrospinal fluid leak was encountered in 1 subject (2.9%). 34 subjects (97.1%) had a normal albeit slow gait by the sixth post-operative day. Complete tumor removal with a very low morbidity in our series suggest that the enlarged translabyrinthine and transapical extension type I approach offers excellent control of the neurovascular structures in the cerebellopontine angle as also of the large vestibular schwannoma itself aiding complete removal. It also offers the advantage of management of the interrupted facial nerve at the primary procedure itself since the proximal and distal segments are in the operative field.

Cystic vestibular schwannoma: classification, management, and facial nerve outcomes

OBJECTIVE

Review of postoperative morbidity and facial nerve outcomes of cystic vestibular schwannoma (CVS) patients compared with solid vestibular schwannoma (SVS) patients and a proposal for a new CVS classification system.

STUDY DESIGN

Retrospective review.

SETTING

Tertiary care facility.

PATIENTS

Ninety-six patients with surgically treated CVS (1998-2008). Outcomes were assessed in a subpopulation of 57 patients with greater than or equal to 1-year follow-up compared with 57 SVS patients.

INTERVENTION

Fifty-six CVS patients underwent the enlarged translabyrinthine approach with transapical extension (Type I), and 1 patient underwent a transcochlear/transzygomatic approach.

MAIN OUTCOME MEASURE

Preoperative and postoperative (at least 1 yr) House-Brackmann facial nerve (HBFN) grade evaluation.

RESULTS

Favorable HBFN grades (I-III) were observed in 46 (81%) CVS patients, and unfavorable HBFN grades (IV-VI) were seen in 11 (19%) CVS patients. Comparison of tumor size and 1-year HBFN grades showed significant, moderate to strong, Pearson correlation (0.38). Comparison of long-term facial nerve outcomes with a sample of 57 matched SVS patients showed no significant difference (p = 0.74). When the tumor was adherent to the facial nerve and a dissection plane could not be developed between the cyst wall and the nerve, only subtotal resection could offer the CVS patients a normal facial nerve outcome.

CONCLUSION

In most CVS cases, complete resection should be foreseen. Central and thick-walled tumors can be removed in almost all cases. However, when peripheral thin-walled, adherent, cystic tumors are confronted and the cysts are medially or anteriorly located, we recommend subtotal resection, leaving portions of the cyst walls on neurovascular structures and on the facial nerve. This surgical strategy allows us to improve facial nerve outcomes and to reduce complications.