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

Dural Venous Sinus Thrombosis After Vestibular Schwannoma Surgery: Should We Anticoagulate?

BACKGROUND

The incidence of dural venous sinus thrombosis (DVST) following vestibular schwannoma (VS) surgery remains understudied. The diverse clinical presentation complicates forming anticoagulation treatment guidelines. This meta-analysis aimed to investigate the incidence of DVST post-VS surgery and to evaluate the role of anticoagulation.

METHODS

A systematic review, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist, was conducted. Studies reporting DVST incidence after VS surgery were included. DVST incidence stratified by detection method was the primary outcome. Adverse events per treatment strategy (anticoagulation or no anticoagulation) were the secondary outcome. Pooled incidence with respective 95% confidence intervals were calculated using the random-effects model via the DerSimonian and Laird method.

RESULTS

The overall DVST incidence post-VS resection was 15.5% (95% confidence interval: 10.3%, 22.5%; 10 studies). Stratification by detection method revealed 29.4% (19.2%, 42.3%) for magnetic resonance imaging, 8.2% (3.2%, 19.5%) for computed tomography, and 0.7% (0.2%, 2.8%) upon clinical suspicion. The pooled incidence of adverse events was 16.1% (6.4%, 35.0%) for the anticoagulation treatment and 4.4% (1.4%, 12.9%) for no anticoagulation treatment, with one mortality case being among the adverse events in this latter group.

CONCLUSIONS

DVST after VS surgery is more common than initially perceived, predominantly presenting asymptomatically. Variability in anticoagulation protocols hinders the establishment of definitive therapeutic stances; nevertheless, there is no supporting evidence to promote anticoagulation administration for DVST. This begs the need for further institutional comparative studies with a proper adjustment for confounding and well-defined anticoagulation regimens.

Venous Sinus Thrombosis-Associated with Posterior Cranial Fossa Surgery. A Systematic Review and Meta-Analysis of Natural History, Risk Factors, Treatment, and Outcome

BACKGROUND

Venous sinus thromboses (VSTs) are rare complications of neurosurgical procedures in the proximity of the dural sinuses. Surgery of the posterior cranial fossa (PCF) and particularly of the cerebellopontine angle (CPA) shows increased risk of VST. VST management is challenging because anticoagulant therapy must be balanced with the risk of postoperative bleeding. We performed a systematic review and meta-analysis to summarize the most important neuroradiologic and clinical aspects of VST after PCF/CPA surgery.

METHODS

We performed a comprehensive literature search to identify articles reporting data on VST after PCF/CPA surgery. We selected only comparative studies providing adequate neuroimaging assessing VST and a control group.

RESULTS

We included 13 articles reporting 1855 patients. VST occurred in 251/1855 cases (estimated incidence, 17.3%; 95% confidence interval [CI], 12.4%-22.2%). Only presigmoid approach (odds ratio [OR], 2.505; 95% CI, 1.161-5.404; P = 0.019) and intraoperative sinus injury (OR, 8.95; 95% CI, 3.43-23.34; P < 0.001) showed a significant association with VST. VST-related symptoms were reported in 12/251 patients with VST (pooled incidence, 3.1%; 95% CI, 1%-5.2%). In particular, we found a significantly increased OR of cerebrospinal fluid leak (OR, 3.197; 95% CI, 1.899-5.382; P < 0.001) and cerebrospinal fluid dynamic alterations in general (OR, 3.625; 95% CI, 2.370-5.543; P < 0.001). Indications for VST treatment were heterogeneous: 58/251 patients underwent antithrombotics, with 6 treatment-related bleedings. Recanalization overall occurred in 56.4% (95% CI, 40.6%-72.2%), with no significant difference between treated and untreated patients. However, untreated patients had a favorable outcome.

CONCLUSIONS

VST is a relatively frequent complication after PCF/CPA surgery and a presigmoid approach and intraoperative sinus injury represent the most significant risk factors. However, the clinical course is generally benign, with no advantage of antithrombotic therapy.

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.

Presentation and Management of Cerebral Venous Sinus Thrombosis After Supratentorial Craniotomy

BACKGROUND AND OBJECTIVES

Cerebral venous sinus thrombosis (CVST) after supratentorial craniotomy is a poorly studied complication, for which there are no management guidelines. This study assessed the incidence, associated risk factors, and management of postoperative CVST after awake craniotomy.

METHODS

This is an observational, retrospective, monocentric analysis of patients who underwent a supratentorial awake craniotomy. Postoperative CVST was defined as a flow defect on the postoperative contrast-enhanced 3D T1-weighted sequence and/or as a T2* hypointensity within the sinus.

RESULTS

In 401 supratentorial awake craniotomies (87.3% of diffuse glioma), the incidence of postoperative CVST was 4.0% (95% CI 2.5-6.4): 14/16 thromboses located in the superior sagittal sinus and 12/16 located in the transverse sinus. A venous sinus was exposed during craniotomy in 45.4% of cases, and no intraoperative injury to a cerebral venous sinus was reported. All thromboses were asymptomatic, and only two cases were diagnosed at the time of the first postoperative imaging (0.5%). Postoperative complications, early postoperative Karnofsky Performance Status score, and duration of hospital stay did not significantly differ between patients with and without postoperative CVST. Adjusted independent risk factors of postoperative CVST were female sex (adjusted Odds Ratio 4.00, 95% CI 1.24-12.91, P = .021) and a lesion ≤1 cm to a venous sinus (adjusted Odds Ratio 10.58, 95% CI 2.93-38.20, P < .001). All patients received standard prophylactic-dose anticoagulant therapy, and none received treatment-dose anticoagulant therapy. No thrombosis-related adverse event was reported. All thromboses presented spontaneous sinus recanalization radiologically at a mean of 89 ± 41 days (range, 7-171).

CONCLUSION

CVST after supratentorial awake craniotomy is a rare event with satisfactory clinical outcomes and spontaneous sinus recanalization under conservative management without treatment-dose anticoagulant therapy. These findings are comforting to neurosurgeons confronted with postoperative MRI reports suggesting CVST.

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.

Postoperative Cerebral Venous Sinus Thrombosis Following a Retrosigmoid Craniotomy-A Clinical and Radiological Analysis

Postoperative cerebral venous sinus thrombosis (CVST) is a rare complication of the retrosigmoid approach. To address the lack of literature, we performed a retrospective analysis. The thromboses were divided into those demonstrating radiological (rCVST) and clinical (cCVST) features, the latter diagnosed during hospitalization. We identified the former by a lack of contrast in the sigmoid (SS) or transverse sinuses (TS), and evaluated the closest distance from the craniotomy to quantify sinus exposure. We included 130 patients (males: 52, females: 78) with a median age of 46.0. They had rCVST in 46.9% of cases, most often in the TS (65.6%), and cCVST in 3.1% of cases. Distances to the sinuses were not different regarding the presence of cCVST (p = 0.32 and p = 0.72). The distance to the SS was not different regarding rCVST (p = 0.13). However, lower exposure of the TS correlated with a lower incidence of rCVST (p = 0.009). When surgery was performed on the side of the dominant sinuses, rCVSTs were more frequent (p = 0.042). None of the other examined factors were related to rCVST or cCVST. Surgery on the side of the dominant sinus, and the exposing of them, seems to be related with rCVST. Further prospective studies are needed to identify the risk factors and determine the best management.

Post-operative segmental cerebral venous sinus thrombosis: risk factors, clinical implications, and therapeutic considerations

Cerebral venous sinus thromboses (CVSTs) are rare complications of neurosurgical interventions and their management remains controversial as most of cases appear clinically silent. Here, we analyzed our institutional series of patients with CVSTs evaluating clinical and neuroradiological characteristics, risk factors, and outcome. From the analysis of our institutional PACS, we collected a total of 59 patients showing postoperative CVSTs after supratentorial or infratentorial craniotomies. For every patient, we collected demographics and relevant clinical and laboratory data. Details on thrombosis trend were retrieved and compared along the serial radiological assessment. A supratentorial craniotomy was performed in 57.6% of cases, an infratentorial in 37.3%, while the remaining were a single cases of trans-sphenoidal and neck surgery (1.7%, respectively). A sinus infiltration was present in almost a quarter of patients, and in 52.5% of cases the thrombosed sinus was exposed during the craniotomy. Radiological signs of CVST were evident in 32.2% of patients, but only 8.5% of them developed a hemorrhagic infarct. CVST-related symptoms were complained by 13 patients (22%), but these were minor symptoms in about 90%, and only 10% experienced hemiparesis or impaired consciousness. The majority of patients (78%) remained completely asymptomatic along the follow-up. Risk factors for symptoms occurrence were interruption of preoperative anticoagulants, infratentorial sinuses involvement and evidence of vasogenic edema and venous infarction. Overall, a good outcome defined mRS 0-2 was observed in about 88% of patients at follow-up. CVST is a complication of surgical approaches in proximity of dural venous sinuses. CVST usually does not show progression and courses uneventfully in the vast majority of cases. The systematic use of post-operative anticoagulants seems to not significantly influence its clinical and radiological outcome.

Asymptomatic Postoperative Cerebral Venous Sinus Thrombosis After Posterior Fossa Tumor Surgery: Incidence, Risk Factors, and Therapeutic Options

BACKGROUND

Cerebral venous sinus thrombosis (CVST) is a known complication of posterior fossa surgery near the sigmoid and transverse sinus. The incidence and treatment of postoperative asymptomatic CVST are controversial.

OBJECTIVE

To analyze incidence, risk factors, and management of asymptomatic postoperative CVST after posterior fossa tumor surgery.

METHODS

In this retrospective, single-center study, we included all patients who underwent posterior fossa tumor surgery in the semisitting position between January 2013 and December 2020. All patients underwent preoperative and postoperative imaging using MRI with/without additional computed tomography angiography. We analyzed the effect of demographic and surgical data on the incidence of postoperative CVST. Furthermore, therapeutic anticoagulation or conservative treatment for postoperative CVST and the incidence of intracranial hemorrhage were investigated.

RESULTS

In total, 266 patients were included. Thirty-three of 266 (12.4%) patients developed postoperative CVST. All patients were asymptomatic. Thirteen of 33 patients received therapeutic anticoagulation, and 20 patients did not. Univariate analysis showed that age ( P = .56), sex ( P = .20), American Society of Anesthesiology status ( P = .13), body mass index ( P = .60), and length of surgery ( P = .176) were not statistically correlated with postoperative CVST. Multivariate analysis revealed that meningioma ( P < .001, odds ratio 11.3, CI 95% 4.1-31.2) and vestibular schwannoma ( P = .013, odds ratio 4.4, CI 95% 1.3-16.3) are risk factors for the development of new postoperative CVST. The use of therapeutic anticoagulation to treat postoperative CVST was associated with a higher rate of intracranial hemorrhage (n = 4, P = .017).

CONCLUSION

Tumor entity influences the incidence of postoperative CVST. In clinically asymptomatic patients, careful decision making is necessary whether to initiate therapeutic anticoagulation or not.

Management of Complications in Vestibular Schwannoma Surgery

Microsurgical removal of acoustic neuroma has advanced tremendously; however, complications still occur. Facial nerve injury is the most common detrimental complication and should take precedence over gross tumor removal in cases where there is an unfavorable tumor-facial nerve interface. Cerebrospinal fluid leakage can occur even with meticulous closure techniques and is generally treatable with either lumbar-subarachnoid drainage or revision wound closure. Meningitis is a serious complication that requires a high index of suspicion in the postoperative period. Other less common complications include intraoperative and postoperative vascular injuries. Early identification and treatment can prevent devastating outcomes.

Association of Postoperative Sigmoid Sinus Occlusion and Cerebrospinal Fluid Leak in Translabyrinthine Surgery

OBJECTIVE

To characterize the incidence of sigmoid sinus occlusion (SSO) following translabyrinthine (TL) surgery for posterior fossa tumor resection and determine the association with cerebrospinal fluid (CSF) leak.

STUDY DESIGN

Retrospective case series.

SETTING

Tertiary referral center.

METHODS

Patients undergoing TL surgery for vestibular schwannoma from 2012 to 2020 were included. Demographic data, medical history, preoperative tumor length and volume, and postoperative complications including CSF leak were recorded. Neuroradiology review of postoperative magnetic resonance imaging was used to determine the presence or absence of flow through the sigmoid sinus.

RESULTS

Of 205 patients undergoing TL, 21 (10.2%) experienced CSF leak postoperatively. Overall 56 (27%) demonstrated SSO on immediate postoperative magnetic resonance imaging. CSF leaks were more likely in those with SSO (19.6%) than those without SSO (6.7%; odds ratio, 3.54 [95% CI, 1.25-10.17]). Tumor volume and body mass index were not significantly associated with CSF leak. In total, 105 (51%) patients had some degree of sigmoid sinus thrombosis, but nonocclusive thrombosis was not associated with CSF leak.

CONCLUSION

SSO after TL approaches is common and appears to be significantly associated with postoperative CSF leak development. Minimizing manipulation of the sigmoid sinus during TL surgery and compression after surgery may have a role in preventing CSF leak.

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.

Dural sinus thrombosis after resection of vestibular schwannoma using suboccipital retrosigmoid approach-thrombosis classification and management proposal

Dural sinus thrombosis is one of the complications after posterior fossa surgery. However, that topic is not described well with regard to vestibular schwannoma surgery using the unique suboccipital retrosigmoid approach. We analyzed retrospectively medical records and radiological investigations of 116 patients. The including criteria were histopathologically confirmed vestibular schwannoma operated on using the retrosigmoid approach, preoperative and postoperative contrast-enhanced MRI, and at least 1-year follow-up. The patient group included 36% males and 64% females. The average age was 47.3 ± 13.9 years. Sixty percent of the tumors were classified as T4b according to the Hannover scale and their mean volume was 13.73 ± 10.28 cm³. There were no signs of thrombosis preoperatively. Postoperative changes in the dural sinuses were found in 26 (22%) cases. In 7 (27%) cases, there was an external compression by the hemostatic agent, and in 19 (73%) cases, a thrombus was visualized in the sinus lumen. The size of the sinus, age, and the tumor size were not risk factors for thrombosis, whereas an intraoperative sinus injury was a statistically significant risk factor (p = 0.0012). All of the patients diagnosed with thrombosis were in good clinical condition in long-term follow-up, except one fatal case. Complete recanalization was observed in 58% of cases after 1-year follow-up. Postoperative changes in the dural venous sinuses are a frequent finding after vestibular schwannoma surgery using the suboccipital retrosigmoid approach. Intraoperative dural injury is a risk factor for thrombosis. Thrombosis in that group of patients is usually asymptomatic and does not influence the prognosis.

The role of anticoagulation for superior sagittal sinus thrombosis following craniotomy for resection of parasagittal/parafalcine meningiomas

OBJECTIVE

The safety and efficacy of anticoagulation in managing superior sagittal sinus (SSS) thrombosis remains unclear. The present study investigated the relationship between anticoagulation and cerebrovascular complications in parasagittal/parafalcine meningioma patients presenting with post-surgical SSS thrombosis.

METHODS

We analyzed 266 patients treated at a single institution between 2005 and 2020. Bivariate analysis was conducted using the Mann-Whitney U test and Fisher's exact test. Multivariate analysis was conducted using a logistic regression model. Blood thinning medications investigated included aspirin, warfarin, heparin, apixaban, rivaroxaban, and other novel oral anticoagulants (NOACs). A symptomatic SSS thrombosis was defined as a radiographically apparent thrombosis with new headaches, seizures, altered sensorium, or neurological deficits.

RESULTS

Our patient cohort was majority female (67.3%) with a mean age ([Formula: see text] SD) of 58.82 [Formula: see text] 13.04 years. A total of 15 (5.6%) patients developed postoperative SSS thrombosis and 5 (1.9%) were symptomatic; 2 (0.8%) symptomatic patients received anticoagulation. None of these 15 patients developed cerebrovascular complications following observation or anticoagulative treatment of asymptomatic SSS thrombosis. While incidence of any other postoperative complications was significantly associated with SSS thrombosis in bivariate analysis (p = 0.015), this association was no longer observed in multivariate analysis (OR = 2.15, p = 0.16) when controlling for patient age, sex, and anatomical location of the tumor along the SSS.

CONCLUSIONS

Our single-institution study examining the incidence of SSS thrombosis and associated risk factors highlights the need for further research efforts better prognosticate this adverse outcome. Conservative management may represent a viable treatment strategy for patients with SSS thrombosis.

Acute Sigmoid Sinus Compromise Following Skull Base Procedures: Is a "Laissez-Faire" Approach Best?

Objective  Venous sinus compromise (VSC) of the sigmoid sinus can manifest as either venous sinus thrombosis, stenosis, or a combination of the two. It may occur following retro and presigmoid craniotomy, even in the absence of overt intraoperative sinus injury. Currently, the optimal management of VSC in the perioperative period is not well established. We report our incidence and management of VSC following skull base surgery around the sigmoid sinus. Patients and Methods  A retrospective chart review of all patients undergoing presigmoid, retrosigmoid, or combined approach by the senior author from 2014 to 2019 was performed. Main Outcome Measures  Charts were reviewed for patient demographics, surgical details, details of venous sinus compromise, and patient outcomes. Statistical analyses were performed using R 3.6.0 (R Project). Results  A 115 surgeries were found with a total of 13 cases of VSC (overall incidence of 11.3%). Nine cases exhibited thrombosis and four stenosis. There were no statistically significant differences between the groups with (group 1) or without (group 2) VSC. Operation on the side of the dominant sinus did not predispose to postoperative VSC. Five patients received antiplatelet medication in the perioperative period. There was no difference in outcomes in the group that did not receive antiplatelet medication versus those who did. Conclusion  Acute iatrogenic sigmoid sinus compromise can be managed expectantly. We believe that the treatment for each instance of VSC must be individualized, considering the symptoms of the patient, rather than applying a universal algorithm.

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.

Anatomic Assessment of the Limits of an Endoscopically Assisted Retrolabyrinthine Approach to the Internal Auditory Canal

Objective  Data regarding the surgical advantages and anatomic constraints of a hearing-preserving endoscopic-assisted retrolabyrinthine approach to the IAC are scarce. This study aimed to define the minimum amount of retrosigmoid dural exposure necessary for endoscopic exposure of the IAC and the surgical freedom of motion afforded by this approach. Methods  Presigmoid retrolabyrinthine approaches were performed on fresh cadaveric heads. The IAC was exposed under endoscopic guidance. The retrosigmoid posterior fossa dura was decompressed until the fundus of the IAC was exposed. Surgical freedom of motion at the fundus was calculated after both retrolabyrinthine and translabyrinthine approaches. Results  The IAC was entirely exposed in nine specimens with a median length of 12 mm (range: 10-13 mm). Complete IAC exposure could be achieved with 1 cm of retrosigmoid dural exposure in eight of nine mastoids. For the retrolabyrinthine approach, the median anterior-posterior surgical freedom was 13 degrees (range: 6-23 degrees) compared with 46 degrees (range: 36-53 degrees) for the translabyrinthine approach ( p  = 0.014). For the retrolabyrinthine approach, the median superior-inferior surgical freedom was 40 degrees (range 33-46 degrees) compared with 47 degrees (range: 42-51 degrees) for the translabyrinthine approach ( p  = 0.022). Conclusion  Using endoscopic assistance, the retrolabyrinthine approach can expose the entire IAC. We recommend at least 1.5 cm of retrosigmoid posterior fossa dura exposure for this approach. Although this strategy provides significantly less instrument freedom of motion in both the horizontal and vertical axes than the translabyrinthine approach, it may be appropriate for carefully selected patients with intact hearing and small-to-medium sized tumors involving the IAC.

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.