The Incidence of Cerebrospinal Fluid Leak after Vestibular Schwannoma Surgery

Transnasal Fluoroscopic-Guided Eustachian Tube Obliteration With a Liquid Embolic Agent for a Recurrent Cerebrospinal Fluid Leak After Translabyrinthine Schwannoma Surgery: A Case Series

OBJECTIVE

Postoperative cerebrospinal fluid (CSF) leak after schwannoma surgery occurs in up to 10% of patients. Conventional surgical treatment including fat and muscle packing can prove unsuccessful. We describe a minimally invasive, imaging-guided approach to CSF fistula treatment.

PATIENTS

We describe two patients and three procedures with recurrent CSF rhinorrhea after translabyrinthine vestibular or facial nerve schwannoma surgery. First-line procedures including CSF diversion and repeat middle ear packing failed to close the leaks.

INTERVENTION

Endonasal endoscopic, fluoroscopic-guided obliteration of the Eustachian tube with n -butyl cyanoacrylate.

MAIN OUTCOME MEASURE

Recurrence of a CSF leak.

RESULTS

After treatment, the CSF leak ceased with no recurrence. One patient's facial nerve dysfunction worsened after the procedure.

CONCLUSIONS

This case series highlights a recently described technique of imaging-guided Eustachian tube obliteration using liquid embolic agent. The procedure was effective in treating recurrent CSF leaks but might cause facial nerve dysfunction.

Translabyrinthine versus Retrosigmoid Approach for Vestibular Schwannoma: A Systematic Review and An Updated Meta-Analysis

OBJECTIVE

Several approaches can be used in the surgical treatment of vestibular schwannoma (VS), and the best approach remains uncertain in the literature. This systematic review and meta-analysis aim to compare the translabyrinthine approach (TLA) with the retrosigmoid approach (RSA) for VS in terms of postoperative complications.

DATA SOURCES

PubMed, Web of Science, Embase, and Cochrane.

REVIEW METHODS

The primary outcome was cerebrospinal fluid (CSF) leak; secondary outcomes were facial nerve dysfunction (FND), length of stay (LOS), and meningitis. Statistical analysis was performed using RStudio 2024.04.1 + 748. Heterogeneity was assessed with I² statistics. We performed sensitivity analysis with subgroup analysis and meta-regression. Risk of bias was assessed using ROBINS-I.

RESULTS

Out of 1140 potential articles, 21 met the inclusion criteria. Among the 4572 patients, 2687 and 1885 patients in the TLA and RSA groups, respectively. No significant differences were found in CSF leak (odds ratio [OR] 1.03; 95% confidence interval [CI] 0.81,1.32; P = .794) or meningitis (OR 1.05; 95% CI 0.45, 2.43; P = .73). Meta-regression showed no association with CSF leak and the number of cases per center or publication year. The TLA is associated with a shorter LOS (MD -1.20; 95% CI -1.39, -1.01; P < .01) and a higher chance of having and HB 4 or lower compared to patients who underwent RSA (OR 0.30; 95% CI 0.10, 0.89; P = .03).

CONCLUSION

There was no difference in the odds of CSF leak or meningitis between the groups. In addition, the TLA has a shorter LOS and a higher chance of a better facial nerve outcome compared to the RSA.

A novel technique to avoid cerebrospinal fluid leaks following middle fossa approaches: Identifying a new triangle in the middle fossa

Background

Skull-based approaches involving the middle fossa (MF) can be complicated by postoperative cerebrospinal fluid (CSF) leaks. Most of these CSF leaks are due to inadvertent entry into the eustachian tube (ET) or incomplete packing of surrounding air cells. Air cells are routinely plugged with bone wax during surgery; however, CSF leaks due to entry into the ET are often not recognized. Our objective was to define a safe zone for drilling that would avoid entry into the ET during MF approaches.

Methods

Ten cadaveric specimens were fixed in formalin and injected with latex. Twenty sides were dissected and examined under a microscope. We exposed and identified the petrous internal carotid artery (ICA), ET, and all surrounding anatomical landmarks.

Results

We identified a triangle bordered by the lateral aspect of the third division of the trigeminal nerve (V3), the lateral aspect of the petrous ICA, and an imaginary line through the middle meningeal artery connecting V3 to the petrous ICA. This triangle was then bisected at the base, creating a medial and lateral sub-triangle. In all 20 cadaveric exposures, the ET was in the lateral sub-triangle and did not extend into the medial sub-triangle.

Conclusion

Our findings demonstrate that entry into the ET while exposing the petrous ICA during MF approaches can be safely avoided by drilling in the medial sub-triangle. Drilling in the lateral sub-triangle will lead to entry into the ET, increasing the risk of a postoperative CSF leak.

Skull Base Repair following Resection of Vestibular Schwannoma: A Systematic Review (Part 2: The Translabyrinthine Approach)

Objectives  Despite advances in skull base reconstruction techniques, cerebrospinal fluid (CSF) leaks remain a relatively common complication after translabyrinthine (TL) vestibular schwannoma (VS) surgery. We conducted a systematic review to synthesize the repair techniques and materials used in TL VS surgery to prevent CSF leaks. Design  A systematic review of studies published since 2000 reporting techniques to prevent CSF leaks during adult TL VS surgery was conducted. A narrative synthesis of primary repair protocols was produced, and a taxonomy was established. Additionally, the advantages, disadvantages, and associated CSF leak rates of different repair protocols were extracted. Results  All 43 studies were case series, and 39 were retrospective. Repair strategies included heterogeneous combinations of autografts, xenografts, and synthetic materials. A taxonomy was produced, classifying repairs into seven distinct stages, including approaches to the dura, middle ear cleft, air cells, TL bony defect, extra-cranial soft tissue, postoperative dressings, and CSF diversion. The median postoperative incidence of CSF leaks was 6% (interquartile range: 0-10%). Conclusions  This systematic review reveals substantial inter-institutional heterogeneity in intraoperative strategies to prevent CSF leaks following TL VS surgery. However, comparing these techniques is challenging due to the multiple predictive factors for CSF leaks and their inconsistent reporting. We propose a taxonomy of seven stages to classify operative techniques and materials aimed at preventing CSF leaks. We recommend that future evaluations should adopt a prospective approach encompassing data collection strategies that considers all operative stages described by our taxonomy.

Graftless Primary Dural Closure Following Retrosigmoid Approach: Doing More With less

INTRODUCTION

Achieving watertight dural closure without grafts via the retrosigmoid approach can be challenging, contributing to a significant rate of postoperative cerebrospinal fluid (CSF) leaks. This study describes a dural incision technique for achieving primary dural closure without grafts following the retrosigmoid approach and presents clinical data from the authors' experience.

METHODS

Clinical and surgical data of 227 patients who underwent the dural incision technique following the retrosigmoid approach for various pathologies were retrospectively reviewed. To achieve no-graft watertight dural closure, the dural incision involves 2 critical steps: a 1 cm transverse incision of the dura parallel to the foramen magnum to drain CSF from the cisterna magna, and a vertical linear opening of the retrosigmoid dura. Dural incisions were closed watertight with vicryl 4/0 running sutures, without the use of grafts, fibrin glue, hemostatic overlays, or dural substitutes. Pre- or postoperative lumbar drainage was not employed.

RESULTS

Primary watertight dural closure was successfully achieved in all patients without the use of grafts or duraplasty. The average duration of dura closure was 17.7 minutes. During an average follow-up period of 49.3 months, there were no instances of CSF leaks or meningitis.

CONCLUSIONS

In the authors' preliminary experience, the linear dural incision described herein was effective for achieving a no-graft, watertight primary dural closure in the retrosigmoid approach, with no CSF leaks or meningitis in our series. Validation of these preliminary data in a larger patient cohort is necessary.

Development and Clinical Validation of a Hook Effect-Based Lateral Flow Immunoassay Sensor for Cerebrospinal Fluid Leak Detection

BACKGROUND AND OBJECTIVES

Rapid detection of cerebrospinal fluid (CSF) leaks is vital for patient recovery after spinal surgery. However, distinguishing CSF-specific transferrin (TF) from serum TF using lateral flow immunoassays (LFI) is challenging due to their structural similarities. This study aims to develop a novel point-of-care diagnostic assay for precise CSF leak detection by quantifying total TF in both CSF and serum.

METHODS

Capitalizing on the substantial 100-fold difference in TF concentrations between CSF and serum, we designed a diagnostic platform based on the well-known "hook effect" resulting from excessive analyte presence. Clinical samples from 37 patients were meticulously tested using the novel LFI sensor, alongside immunofixation as a reference standard.

RESULTS

The hook effect-based LFI sensor exhibited outstanding performance, successfully discriminating positive clinical CSF samples from negative ones with remarkable statistical significance (positive vs negative t -test; P = 1.36E-05). This novel sensor achieved an impressive 100% sensitivity and 100% specificity in CSF leak detection, demonstrating its robust diagnostic capabilities.

CONCLUSION

In conclusion, our study introduces a rapid, highly specific, and sensitive point-of-care test for CSF leak detection, harnessing the distinctive TF concentration profile in CSF compared with serum. This novel hook effect-based LFI sensor holds great promise for improving patient outcomes in the context of spinal surgery and postsurgical recovery. Its ease of use and reliability make it a valuable tool in clinical practice, ensuring timely and accurate CSF leak detection to enhance patient care.

Jugular Foramen Tumors: Surgical Strategies and Representative Cases

(1) Background: Jugular foramen tumors are complex lesions due to their relationship with critical neurovascular structures within the skull base. It is necessary to have a deep knowledge of the anatomy of the jugular foramen and its surroundings to understand each type of tumor growth pattern and how it is related to the surrounding neurovascular structures. This scope aims to provide a guide with the primary surgical approaches to the jugular foramen and familiarize the neurosurgeons with the anatomy of the region. (2) Methods and (3) Results: A comprehensive description of the surgical approaches to jugular foramen tumors is summarized and representative cases for each tumor type is showcased. (4) Conclusions: Each case should be carefully assessed to find the most suitable approach for the patient, allowing the surgeon to remove the tumor with minimal neurovascular damage. The combined transmastoid retro- and infralabyrinthine transjugular transcondylar transtubercular high cervical approach can be performed in a stepwise fashion for the resection of complex jugular foramen tumors.

Quality of life in patients after vestibular schwannoma surgery

AIM

To evaluate the most important factors of quality of life in patients after vestibular schwannoma surgery.

MATERIALS AND METHODS

Patients with unilateral sporadic occurrence of vestibular schwannoma who underwent surgery via suboccipital-retrosigmoid approach were included in the prospective study (2018-2021). Patients after previous Leksell gamma knife irradiation (or other methods of stereotactic radiosurgery) were excluded. Quality of life was assessed using 10 validated questionnaires that were distributed preoperatively, 3 months and 1 year after the surgery.

RESULTS

A total of 76 patients were included in the study, complete data were analysed in 43 of them (response rate 57%). Grade III and IV represented up to 70% of all tumors. Patients with larger tumors had a significantly higher risk of postoperative facial nerve paresis, liquorrhea and lower probability of hearing preservation. Patients with smaller tumors and those, who suffered from headaches before surgery had more frequent and severe headaches after surgery. Postoperative headaches were associated with higher incidence of anxiety and tinnitus. More frequent anxiety was also identified in patients with preoperative serviceable hearing who became deaf after surgery. Nevertheless, tinnitus and hearing impairment appeared to have less impact on overall quality of life compared to headaches and facial nerve function.

CONCLUSION

According to our results, tumor size, postoperative function of the facial nerve and occurrence of postoperative headaches had the greatest influence on the overall postoperative quality of life in patients after vestibular schwannoma surgery.

Preventing cerebral spinal fluid leakage following endoscopy through a burr hole using a novel watertight closure: technical note

BACKGROUND

Cerebrospinal fluid (CSF) leakage is a common complication after neuroendoscopic surgery through a burr hole and can lead to further complications including infection.

METHODS

We describe the use of a dural substitute larger than the burr hole itself, placed over the burr hole and then secured underneath a burr hole cover by microscrews running through the graft itself into the underlying skull.

RESULTS

This simple technical modification contributes to achieving a watertight seal to aid in preventing CSF leakage in this setting.

CONCLUSIONS

Our technical modification of endoscopy through a burr hole may help to prevent postoperative CSF leak and secondary CSF infections.

Elevated Body Mass Index Associated with Cerebrospinal Fluid Leak after Lateral Skull Base Surgery: A Systematic Review and Meta-analysis

OBJECTIVE

To determine if body mass index (BMI) increases the risk of cerebrospinal fluid (CSF) leak after lateral skull base surgery.

DATA SOURCES

CINAHL, PubMed, and Scopus were searched from January 2010 to September 2022 for articles published in English.

STUDY SELECTION

Articles that reported BMI or obesity with and without CSF leaks after lateral skull base surgery were included.

DATA EXTRACTION

Two reviewers (F.G.D. and B.K.W.) independently performed study screening, data extraction, and risk of bias assessment.

DATA SYNTHESIS

A total of 11 studies and 9,132 patients met inclusion criteria. Meta-analysis of mean difference (MD), odds ratio (OR), proportions, and risk ratio (RR) were calculated using RevMan 5.4 and MedCalc 20.110. BMI for patients with CSF leak after lateral skull base surgery (29.39 kg/m2, 95% confidence interval [CI] = 27.75 to 31.04) was significantly greater than BMI for patients without CSF leak after lateral skull base surgery (27.09 kg/m2, 95% CI = 26.16 to 28.01) with an MD of 2.21 kg/m2 (95% CI = 1.09 to 3.34, p = 0.0001). The proportion of patients with BMI ≥ 30 kg/m2 that had a CSF leak was 12.7%, and the proportion of patients with BMI < 30 kg/m2 (control) that had a CSF leak was 7.9%. The OR for CSF leak after lateral skull base surgery in patients with BMI ≥ 30 kg/m2 was 1.94 (95% CI = 1.40 to 2.68, p < 0.0001), and the RR was 1.82 (95% CI = 1.36 to 2.43, p < 0.0001).

CONCLUSION

Elevated BMI increases the risk of CSF leak after lateral skull base surgery.

LEVEL OF EVIDENCE

IIa.

Translabyrinthine Approach for Sporadic Vestibular Schwannoma: Patient Selection, Technical Pearls, and Patient Outcomes

Herein we briefly describe the translabyrinthine approach to vestibular schwannoma resection as well as a focused literature review as to the best candidates, technical recommendations, and key outcomes with respect to other approaches.

Endoscopic Endonasal Eustachian Tube Obliteration as a Treatment for Tension Pneumocephalus After Translabyrinthine Resection of Vestibular Schwannoma

OBJECTIVE

Cerebrospinal fluid leak and pneumocephalus are rare but potentially devastating complications associated with translabyrinthine resection of cerebellopontine angle masses. Persistent pneumocephalus despite proximal eustachian tube (ET) obliteration is rare. We describe, to our knowledge, the first report of successful management of tension pneumocephalus by endoscopic endonasal ET obliteration using a novel V-loc (Covidien; Medtronic, Minneapolis, MN) suture technique.

PATIENTS

A 63-year-old man presented with altered mental status 10 months after translabyrinthine excision of a left cerebellopontine angle vestibular schwannoma measuring 2.8 × 2.9 × 3.3 cm. Computed tomography demonstrated diffuse ventriculomegaly and new pneumocephalus along the right frontal lobe, lateral ventricles, and third ventricle, and air within the left translabyrinthine resection cavity.

INTERVENTION

The patient underwent left-sided endoscopic endonasal ET obliteration using 2-0, 9-inch V-loc suture.

MAIN OUTCOME MEASURE

Postoperatively, the patient's mental status improved with a decrease in size of the lateral and third ventricles on computed tomography.

CONCLUSION

Endoscopic endonasal ET obliteration, a technique previously applied to recalcitrant cerebrospinal fluid leaks, is a safe and reasonable alternative to reentering the original surgical site for patients with pneumocephalus after lateral skull base surgery. Utilizing a V-loc suture for this technique instead of a traditional suture may improve procedural ease and speed.

Primary Dural Repair Using Titanium Microclips Following Lateral Skull Base Surgery

Objective Standard techniques for primary dural repair following lateral skull base surgery are both technically challenging and time consuming without the potential for primary dural repair. Inadequate closure may result in postoperative cerebrospinal fluid (CSF) leak infectious sequalae. Traditional methods of dural repair rely on secondary obliteration of the CSF fistula. We hypothesized that the use of nonpenetrating titanium microclips may serve as a useful adjunct in primary dural repair or the establishment of an immobile repair layer following lateral skull base surgery.

Methods Here, we report a novel technique for primary dural repair using nonpenetrating titanium microclips as an adjunct to standard techniques in a series of six patients with lateral skull base pathologies.

Results A total of six consecutive lateral skull base tumor patients with titanium microclip dural reconstruction were included in our case series. Lateral skull base pathologies represented in this group included two jugular foramen schwannomas, one vestibular schwannoma, one petroclival meningioma, one glomus jugulare paraganglioma, and one jugular foramen chordoid meningioma.

Conclusion To our knowledge, this is the first report on the use of microclips in repairing dural defects following lateral skull base surgery. Surgical outcomes for this small case series suggest that dural repair of the later skull base with nonpenetrating titanium microclips is a useful adjunct in dural repair following lateral skull base surgery.

Endoscopic Endonasal Eustachian Tube Obliteration for Cerebrospinal Fluid Rhinorrhea: A Case Series and Scoping Review

BACKGROUND

Endoscopic endonasal eustachian tube obliteration (EEETO) is a valuable option for treating cerebrospinal fluid rhinorrhea (CSFR) after lateral skull base surgery. Several small case series describe different techniques because of the rarity of this indication.

OBJECTIVE

To review available literature on EEETO focusing on technique and factors affecting success. We also contribute a new case series using a knotless barbed suture technique.

METHODS

This was a retrospective chart review of EEETO using barbed suture for CSFR at our institution from 2018 to 2021. Scoping review was performed by searching PubMed for articles on EEETO for CSFR. Patients were pooled for data syntheses.

RESULTS

Our retrospective series contained 7 patients. Two patients (28.6%) required revision, but all were ultimately successful. Six studies were identified in scoping review for a combined total of 23 patients. Most of the patients initially underwent translabyrinthine (52.2%) resection of vestibular schwannoma (82.6%). Average time to initial CSFR was 362.6 days (standard deviation ± 1034.2, range 0-4320 days). Twenty-two patients underwent lumbar drain, and 11 underwent prior surgical attempts before EEETO. The initial success rate of EEETO was 65.2%. In 8 patients needing revision, EEETO was ultimately successful in 6. There were no differences in demographics or presentation between successful and revision cases. Seven different techniques were described.

CONCLUSION

EEETO can treat CSFR after lateral skull base surgery. Revision surgery is common and difficult to predict. Several techniques have been described, and utilization of barbed suture is a viable method with comparable success, but without the need for endoscopic knot tying.

Facial Nerve Function After Microsurgical Resection in Vestibular Schwannoma Under Neurophysiological Monitoring

Background

The use of intraoperative neurophysiological monitoring, including direct nerve stimulation (especially the facial nerve), acoustic evoked potentials (AEP) and somatosensory evoked potentials (SSEP), is a helpful tool in the microsurgery of vestibular schwannoma to prevent nerve injury. Patient characteristics and intraoperative and postoperative variables might also influence the postoperative facial nerve function. The study was performed to investigate these variables and the intraoperative neurophysiological monitoring values.

Methods

Seventy-nine patients with vestibular schwannoma were included consecutively into this study. Intraoperative neurophysiological monitoring, including SSEP, AEP, and direct nerve stimulation for facial and trigeminal nerve electromyography, was performed utilizing digital data storage in all cases. The intensity (in volts) of the direct stimulation and the latency (in ms) for the orbicularis oculi and the orbicularis oris muscle and the amplitude (in mV) was measured. Univariate and multivariate statistical analyses concerning the different parameters was performed directly after the operation and in the subsequent follow-ups 3 and 6 months after the operation.

Results

The mean intensity was 0.79 V (SD.29). The latency and amplitude for the oris muscle was 5.2 ms (SD 2.07) and 0.68 mV (SD.57), respectively. The mean latency for the occuli muscle was 5.58 ms (SD 2.2) and the amplitude was 0.58 mV (SD 1.04). The univariate and multivariate statistical analyses showed significance concerning the postoperative facial nerve function and the amplitude of the direct stimulation of the facial nerve in the orbicularis oris muscle (p = 0.03), so repeated direct nerve stimulation might show FN function deterioration. The mean diameter of the tumors was 24 mm (range 10–57 mm). Cross total resection and near total was achieved in 76 patients (96%) and subtotal in three patients (4%). The preoperative House–Brakeman score (HBS) 1 was constant in 65 (82%) cases. The mortality in our series was 0%; the overall morbidity was 10%. The HBS was not influenced concerning the extent of resection. The mean follow-up was 28 months (range 6 to 60 months). The limitations of the study might be a low number of patients and the retrospective character of the study.

Conclusion

Intraoperative neurophysiological monitoring is crucial in vestibular schwannoma surgery. Repeated direct nerve stimulation and a detected decreased amplitude might show facial nerve function deterioration.

Treatment, Outcome, and Relapse of Spontaneous and Nonspontaneous Cerebrospinal Fluid Leak

Cerebrospinal fluid (CSF) leak can be spontaneous or nonspontaneous. The management options include conservative treatments, blood patch, and surgical repairs. We compared clinical symptoms, image findings, management options, hospitalization, and relapse rates among different causes of CSF leaks. Eighty-one patients were recruited: 20 with spontaneous and 61 with nonspontaneous CSF leaks. Nonspontaneous causes included lumbar puncture, surgery, and trauma. Surgery sites comprised sphenoid, spine, skull base, and calvaria. Spontaneous CSF leak came from the sphenoid or spine. Age, gender, body mass index, initial symptoms, hospitalization, treatment courses, and recurrence rates showed no difference between the groups. The spontaneous group had higher CSF accumulations on their MRIs. MRI pachymeninge enhancement showed the highest sensitivity (78.6%) for intracranial hypotension. Meningitis occurred in 1/3 of sphenoid, skull base, and calvarian surgeries. Earlier reoperation was correlated with shorter hospitalization (r = 0.651), but the recurrence rates were similar. Longer intervals between surgery and CSF leak encouraged reoperation. Among the spontaneous spine and lumbar puncture-related CSF leaks, 57.1% of them responded to 4 days of conservative treatment. Among the trauma-related CSF leaks, 90.9% of them required surgical repair. The demographic data and symptoms were similar in various groups of CSF leak. The symptom onset durations and treatment strategies were different. However, the recurrence rates were similar.

Incidence and Long-Term Health Care Utilization Associated With Pseudomeningocele Repair Following Vestibular Schwannoma Resection: A National Database Analysis

Introduction To compare the healthcare utilization in patients who presented with no pseudomeningocele (PSM) following vestibular schwannoma (VS) surgery (nd-PSM), PSM following VS surgery and required surgical repair (s-PSM) and those who presented with PSM and did not require surgical repair (ns-PSM). Methods MarketScan database was queried using the International Classification of Diseases, ninth and tenth revisions, and current procedural terminology four, from 2000 to 2018. We included patients ≥18 years of age with a PSM diagnosis with at least two years of continuous enrollment. The hospital admissions, outpatient services, medication refills, and associated payments were analyzed. Results Of 1,460 patients, 96.6% (n=1,411) had no PSM following surgery for VS, 2.4% (n=35) were in s-PSM and only 0.95% (n=14) were in ns-PSM cohorts. Patients in the s-PSM cohort incurred higher hospital readmission rate, outpatient payments compared to those in the nd-PSM and ns-PSM cohorts at six months, one-year, and two-years following the following VS resection. At one-year following VS resection, the median combined payments for the s-PSM cohort were $74,683 compared to $42,664 for the ns-PSM and $9,476 for the nd-PSM cohort, p<0.0001. Similarly, at two-years, median combined payments for s-PSM cohort were $83,351 compared to $63,942 for ns-PSM and $18,839 for the nd-PSM cohort, p<0.0001. Conclusion  Patients in the s-PSM cohort incurred eight times and 4.4 times the combined payments at one- and two-years, respectively, compared to the nd-PSM cohort. Also, patients in the ns-PSM cohort incurred 4.5 times and 3.4 times the payments compared to the nd-PSM cohort.

Comparison of Small Intestinal Submucosal Graft and Autologous Tissue in Prevention of CSF leak after Posterior Fossa Craniotomy

Objective  To compare the use of porcine small intestinal submucosal grafts (SISG) and standard autologous material (fascia) in prevention of cerebrospinal fluid (CSF) leak and pseudomeningocele formation after translabyrinthine resection. Setting  Set at the tertiary skull base center. Methods  This is a retrospective chart review. After Institutional Review Board approval, we performed a retrospective cohort study evaluating CSF leak in patients who underwent resection of lateral skull base defects with multilayered reconstruction using either fascia autograft or porcine SISGs. Demographics were summarized with descriptive statistics. Logistic regression was used to compare autograft and xenograft cohorts in terms of CSF complications. Results  Seventy-seven patients underwent lateral skull base resection, followed by reconstruction of the posterior cranial fossa. Of these patients, 21 (27.3%) underwent multilayer repair using SISG xenograft. There were no significant differences in leak-associated complications between autograft and xenograft cohorts. Ventriculoperitoneal shunt was necessary in one (1.8%) autograft and one (4.8) xenograft cases ( p  = 0.49). Operative repair to revise surgical defect was necessary in three (5.4%) autograft cases and none in xenograft cases. Conclusion  The use of SISG as a component of complex skull base reconstruction after translabyrinthine tumor resection may help reduce CSF leak rates and need for further intervention.

Bone Cement Internal Auditory Canal Reconstruction to Reduce CSF Leak After Vestibular Schwannoma Retrosigmoid Approach

OBJECTIVE

To describe rates of cerebrospinal fluid (CSF) rhinorrhea after reconstruction of the IAC with calcium phosphate bone cement during retrosigmoid resections of vestibular schwannomas.

METHODS

A retrospective chart review of 177 patients who underwent retrosigmoid craniotomy and opening of the internal auditory canal for resection of a vestibular schwannoma between January 2016 and September 2019 at a tertiary referral center. Patients with other cerebellopontine angle tumor histology, neurofibromatosis type II, or those undergoing revision surgeries were excluded.

RESULTS

Out of 177 patients, six patients (3.4%) developed postoperative rhinorrhea. Four patients (2.3%) were taken back to the OR for mastoidectomy and repair of CSF leak. Three of these patients were noted to have a CSF leak from the peri-labyrinthine air cells, and one was found to have a leak from the craniotomy site communicating with the mastoid air cells. Two patients were conservatively managed with diuretics and had resolution of their CSF leak. Six patients (3.4%) were readmitted for postoperative infection. Two patients were diagnosed with meningitis (1.1%), one aseptic and one H. Influenza, and three patients developed surgical site infections (1.6%). One patient was empirically treated with antibiotics and ultimately had a negative CSF culture.

CONCLUSIONS

Our results demonstrate that the use of calcium phosphate bone cement for IAC closure in retrosigmoid resection of vestibular schwannomas is a safe and effective technique with low rates of postoperative CSF rhinorrhea.

Impact of Reconstruction With Hydroxyapatite Bone Cement on CSF Leak Rate in Retrosigmoid Approach to Vestibular Schwannoma Resection: A Review of 196 Cases

OBJECTIVE

To assess the impact of reconstructive technique on the incidence of cerebrospinal fluid (CSF) leak following retrosigmoid approach to acoustic neuroma resection.

STUDY DESIGN

Retrospective case series.

SETTING

Academic medical center.

PATIENTS

A total of 1,200 patients with acoustic neuromas presented to our institution from 2005 to 2018. Of these, 196 patients underwent surgical resection via a retrosigmoid approach.

INTERVENTION

At our institution, internal auditory canal (IAC) reconstruction following a retrosigmoid approach was performed with bone wax and muscle plug or Norian hydroxyapatite bone cement from 2005 to 2013. Starting in 2014, a newer model of bone cement, Cranios hydroxyapatite, was used exclusively for reconstruction.

MAIN OUTCOME MEASURES

Rates of CSF leak were evaluated across different methods of IAC reconstruction and types of bone cement. Patients whose leaks were attributable to the craniectomy site were excluded from analysis.

RESULTS

The postoperative CSF leak rate among patients who did not receive bone cement for IAC reconstruction was 15.6% (n.5). The leak rate amongst patients who received Norian bone cement was 6.3% (n.4). After introduction of Cranios bone cement, the total leak rate decreased to 1% (n.1). Compared with all other types of closure, Cranios had a significantly reduced rate of postoperative CSF leak (p < 0.005). The leak rate following Cranios versus Norian was also significantly reduced (p < 0.05). Leak rate was not affected by tumor size (p.0.30) or age (p.0.43).

CONCLUSION

CSF leak rate following acoustic neuroma resection was significantly reduced by introduction of Cranios hydroxyapatite bone cement.

Factors associated with cerebrospinal fluid leak after a retrosigmoid approach for cerebellopontine angle surgery

Background

The retrosigmoid approach represents a crucial surgical route to address different lesions in the cerebellopontine angle but cerebrospinal fluid (CSF) leak still remains the most frequent complication after this approach. Here, we analyzed the impact of different factors in CSF leak development after a retrosigmoid approach. Identifying risk factors related to a specific approach may help the surgeon to tailor the perioperative management and to appropriately counsel patients regarding their risk profile.

Methods

We retrospectively reviewed the clinical, surgical, and outcome data of 103 consecutive patients (M/F, 47/56; mean follow-up 35.6 ± 23.9 months) who underwent a retrosigmoid approach for different cerebellopontine angle pathologies and studied the impact of different factors on the occurrence of a CSF leak to univariate and multivariate analysis.

Results

Seventy-nine patients (76.7%) were operated for tumors growing in the cerebellopontine angle. Twenty-four patients (23.2%) underwent microvascular decompression to treat a drug-resistant trigeminal neuralgia. Sixteen patients (15.5%) developed CSF leak in the postoperative course of which six underwent surgical revision. Performing a craniectomy as surgical procedure (P = 0.0450) and performing a reopening procedure (second surgery; P = 0.0079) were significantly associated to a higher risk of developing CSF leak. Moreover, performing a reopening procedure emerged as an independent factor for CSF developing on multivariate analysis (P = 0.0156).

Conclusion

Patients submitted to craniectomy and patients who underwent a second surgery showed an higher CSF leak rate. Ongoing improvement of biomaterial technology may help neurosurgeons to prevent this potentially life-threatening complication.

Cerebrospinal Fluid Leak Following Translabyrinthine Vestibular Schwannoma Surgery-Is Mesh Cranioplasty Necessary for Prevention?

OBJECTIVE

Evaluate the incidence of cerebrospinal fluid leak following vestibular schwannoma surgery for mesh cranioplasty closure versus periosteal closure in the translabyrinthine approach. Determine nonsurgical variables associated with higher rates of cerebrospinal fluid leak following vestibular schwannoma surgery.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary academic referral center.

PATIENTS

One hundred thirty-two patients with adequate documentation who underwent sporadic vestibular schwannoma resection via a translabyrinthine approach between 2000 and 2019.

INTERVENTION

Translabyrinthine excision of vestibular schwannoma with mesh cranioplasty closure or watertight periosteal closure.

MAIN OUTCOME MEASURES

Primary outcome measures included the incidence of postoperative cerebrospinal fluid leak, total length of hospital stay (including the initial hospital stay as well as hospital days during any readmission within 30 days), and total operative time.

RESULTS

Our overall cerebrospinal fluid leak rate was 9.1% with a leak rate of 12.8% in our translabyrinthine titanium mesh closure group and 0% in our translabyrinthine periosteal closure. There was no statistically significant effect of age, body mass index, or size of tumor on the incidence of cerebrospinal fluid leak. There was also no statistically significantly difference between the two groups on length of operative time or number of days spent in the intensive care unit.

CONCLUSION

Mesh cranioplasty is not a prerequisite for achieving a low cerebrospinal fluid leak rate following translabyrinthine approach for vestibular schwannoma resection. In our series, a significantly lower cerebrospinal fluid leak rate was demonstrated with the periosteal closure.

Prevention of cerebrospinal fluid leak after vestibular schwannoma surgery: a case-series focus on mastoid air cells' partition

BACKGROUND

Petrous bone pneumatization may be related to cerebrospinal fluid (CSF) leak secondary to vestibular schwannoma surgery.

OBJECTIVE

To assess the association between petrous bone pneumatization and CSF leak in vestibular schwannoma surgery.

METHODS

A retrospective study included 222 consecutive vestibular schwannoma patients treated via a retrosigmoid or translabyrinthine approach in a 17-year period in one University Hospital. Association of CSF leak and petrous bone pneumatization, as seen on CT scans, was assessed on ANOVA and Student's t or Chi-squared test in case of non-parametric distribution.

RESULTS

One hundred and 75 resections were performed on a retrosigmoid approach and 47 on a translabyrinthine approach. Mean age was 53.6 ± 12.9 years. Mean follow-up was 5 years 6 months. Twenty-six patients (11.7%) showed CSF leak and 8 (3.6%) meningitis. Approach (p = 0.800), gender (p = 0.904), age (p = 0.234), body-mass index (p = 0.462), tumor stage (p = 0.681) and history of schwannoma surgery (p = 0.192) did not increase the risk of CSF leak. This risk was unrelated to mastoid pneumatization (p = 0.266). There was a highly significant correlation between internal acousticus meatus (IAM) posterior wall pneumatization and CSF leak after retrosigmoid surgery (p = 0.008). Eustachian tube packing in the translabyrinthine approach did not decrease risk of CSF leak (p = 0.571).

CONCLUSION

Degree of petrous bone pneumatization was not significantly related to risk of CSF leak, but pneumatization of the posterior IAM wall increased this risk in retrosigmoid surgery. Eustachian tube packing in the translabyrinthine approach is not sufficient to prevent postoperative CSF leak. Both approaches had similar rates of CSF leaks, around 12%.

Role of the neurotologist in posterior fossa meningioma surgery

Posterior fossa meningiomas that impinge on structures of the temporal bone or clivus may be difficult to access for optimal resection that maximizes tumor control and minimizes short- and long-term morbidities. To address this challenge, the contemporary neurosurgery-neurotology team works collaboratively by managing patients jointly at every stage of care: preoperative evaluation, intraoperative intervention, and postoperative treatment. The neurotologist is important at all stages of posterior fossa meningioma surgery. First, detailed preoperative evaluation of auditory, facial, vestibular, and lower cranial nerve integrity enables assessment of new neurologic deficit risk, prognosis of functional recovery, and pros and cons of candidate surgical approaches. Second, intraoperative partitioning of surgical steps by provider and adopting an overlapping tumor resection philosophy creates an efficient and confident surgical team built on trust. Third, postoperative closure of cerebrospinal fluid leak and treatment of facial weakness, audiovestibular dysfunction, and voicing and swallowing impairments organized by the neurotologist reduces the impact of negative outcomes. The role of the neurotologist in posterior fossa meningioma surgery is to deliver nuanced evaluative metrics, facilitate shared decision making, perform precise bone and soft tissue microsurgery, and mitigate perioperative morbidities.

Reducing the risk of cerebrospinal fluid rhinorrhea following translabyrinthine surgery of the posterior fossa

Objective

To describe the procedure and results of an adapted closure and reconstruction technique for translabyrinthine surgery that focuses on identifying and managing potential pathways for CSF egress to the middle ear and Eustachian tube.

Methods

Retrospective review of a cohort of translabyrinthine acoustic neuroma cases that were reconstructed using this technique.

Results

In addition to meticulous packing of potential conduits using soft tissue, hydroxyapatite cement is used to seal opened air cell tracts prior to obliteration of the mastoid defect using adipose tissue. Early results of a small patient cohort using this technique are encouraging and there were no wound infections. There was a single case of CSF rhinorrhea associated with incomplete sealing of opened petrous apex cells, with no recurrence after appropriate implementation of the described protocol during revision surgery.

Conclusion

Proactive management of potential conduits of CSF egress including opened air cell tracts has a high likelihood of reducing rates of rhinorrhea and need for revision surgery after the translabyrinthine approach to the posterior fossa.

Prognostic Factors for the Outcome of Translabyrinthine Surgery for Vestibular Schwannomas

OBJECTIVE

To identify predictors of tumor recurrence and postoperative facial nerve function after translabyrinthine surgery for unilateral vestibular schwannomas.

STUDY DESIGN

Retrospective study.

SETTING

Tertiary referral center.

PATIENTS

Between 1996 and 2017 a total of 596 patients with unilateral vestibular schwannoma underwent translabyrinthine surgery. Pre- and postoperative clinical status, radiological, and surgical findings were evaluated.

INTERVENTIONS

Translabyrinthine surgery.

MAIN OUTCOME MEASURES

Potential predictors for tumor recurrence and facial nerve outcome were analyzed using Cox regression and ordinal logistic regression, respectively.

RESULTS

The extent of tumor removal was total in 32%, near-total in 58%, and subtotal in 10%. In 5.5% (33/596) of patients the tumor recurred. Subtotal tumor resection (p = 0.004, hazard ratios [HR] = 10.66), a young age (p = 0.008, HR = 0.96), and tumor progression preoperatively (p = 0.042, HR = 2.32) significantly increased the risk of recurrence, whereas tumor size or histologic composition did not. A good postoperative facial nerve function (House-Brackmann grade 1-2) was achieved in 85%. The risk of postoperative facial nerve paresis or paralysis increased with tumor size (p < 0.001, OR = 1.52), but was not associated with the extent of tumor removal, histologic composition, or patient demographics.

CONCLUSIONS

Translabyrinthine surgery is an effective treatment for vestibular schwannoma, with a good local control rate and facial nerve outcome. The extent of tumor removal is a clinically relevant predictor for tumor recurrence, as are young patient age and preoperative tumor progression. A large preoperative tumor size is associated with a higher risk of postoperative facial nerve paresis or paralysis.

Risk Factors for 30-Day Non-Neurological Morbidity and Cerebrospinal Fluid Leak in Patients Undergoing Surgery for Vestibular Schwannoma

Introduction  We analyzed perioperative risk factors for morbidity and mortality for the patients undergoing surgical intervention for vestibular schwannoma along with rates of cerebrospinal fluid (CSF) leaks that required surgery. Materials and Methods  Patients undergoing surgery vestibular schwannoma were identified in the American College of Surgeons National Surgical Quality Improvement Program database from 2012 to 2016 using current procedural terminology (CPT) codes for posterior fossa surgical approaches and International Classification of Diseases 9th revision (ICD 9) and ICD 10 codes for peripheral nerve sheath tumor. Preoperative laboratories, comorbidities, and operative times were analyzed along with CSF leaks and unplanned returns to the operating room. Results  Nine-hundred ninety-three patients fit the inclusion criteria. Average age was 51, 41% were male, and 58% were female. Mortality within 30 days of the operation was very low at 0.4%, complications were 7% with infection being the most common at 2.3%, and unplanned reoperations happened in 7.4% of the cases. Dependent functional status (odds ratio [OR]: 5.7, 95% confidence interval [CI]: 1.9-16.6, p  = 0.001), preoperative anemia (OR: 2.4, 95% CI: 1.2-4.5, p  = 0.009), and operative time over 8 hours (OR: 1.9, 95% CI: 1.1-3.4, p  = 0.017) were the only significant predictors of perioperative complications. CSF leak postoperatively occurred in 37 patients (3.7%). Reoperation for CSF leak was necessary in 56.3% of the cases. Operative time over 8 hours was the only independent significant predictor of postoperative CSF leak (OR: 2.2, 95% CI: 1.1-4.3, p  = 0.028). Conclusion  Dependent functional status preoperatively, preoperative anemia, and duration of surgery over 8 hours are the greatest predictors of complications in the 30-day postoperative period.

Lumbar drains: Practical understanding and application for the otolaryngologist

INTRODUCTION

Lumbar drains are frequently used in patients with otolaryngologic concerns. These can be used therapeutically or prophylactically with the primary purpose being to modulate CSF pressure. Within otolaryngology, lumbar drains are most frequently used for cerebrospinal fluid leaks - either due to cerebrospinal fluid fistulas or in skull base surgery as these allow for potential healing of the defect. While not typically placed by otolaryngologists, a basic understanding of lumbar drains is beneficial in the context of patient management.

MANAGEMENT

A lumbar drain is inserted into the intrathecal space in a patient's lumbar spine. Though considered to be a benign procedure, complications are relatively frequent, and adjustment or replacement of the drain may be required. Complications include infection, epidural bleeding, retained hardware, sequelae of relative immobility, or may relate to over-drainage, ranging from mild headache to cranial neuropathies, altered mental status, pneumocephalus, intracranial hemorrhage, and death. While in place, neurologic exams should be performed routinely and should include motor and sensory exams of the lower extremities. A patient should be monitored for fevers, nuchal rigidity, and other signs of infection or meningitis. The CSF fluid should be grossly examined to identify changes, but routine laboratory tests are not typically run on the fluid itself. Drainage rates will vary usually between 5 and 20 mL per hour and must be frequently reassessed and adjusted based upon signs of intracranial hypotension. Drains should be removed when appropriate and should not be left in more than 5 days due to the increased infectious risk.

CONCLUSION

Lumbar drains are important tools used in patients with otolaryngologic pathologies. Otolaryngologists and otolaryngology residents should be familiar with these catheters to determine if they are working correctly and to identify adverse effects as early as possible.

A Systematic Review of Closure Techniques in Lateral Skull Base Tumor Surgery

Introduction  Tumors of the lateral skull base often require collaboration between neurosurgeons and neurotologists for the surgical approach. The three main transosseous surgical approaches are retrosigmoid (RS), translabyrinthine (TL), and middle fossa (MF). The literature reflects a relative paucity regarding the various closure techniques for these approaches and the postoperative complications. We have performed a systematic review comparing closure techniques from each approach. Methods  A systematic review was performed using Ovid MEDLINE (1990-2016) on closure technique and postoperative complications for patients undergoing lateral skull base surgery via the TL, RS, or MF approach. Studies were included if they contained at least 10 patients, described their closure technique, and provided data on postoperative complications. Results  A total of 1,403 studies were reviewed. Of these, 53 studies met inclusion criteria yielding a total of 10,466 subjects in this analysis. The average rate of cerebrospinal fluid leak was 5.3% in the TL approach, 9% in the RS approach, and 6.2% in the MF approach. There was no significant effect of various closure techniques on postoperative wound complications in the MF approach. Multiple factors were identified which affected postoperative wound complication in the RS and TL approaches. Conclusion  There are a plethora of closure techniques for lateral skull base surgery. Several techniques were identified in this review that may affect the postoperative wound complication rates in lateral skull base surgery.

Association Between Body Mass Index and Complications in Acoustic Neuroma Surgery

Objectives

Elevated body mass index (BMI) is a risk factor for surgical complications, but data in acoustic neuroma surgery are conflicting and limited to small single-institution studies. This work evaluates associations between BMI and complications in surgery for acoustic neuroma (AN).

Study Design

Retrospective review.

Setting:

Two tertiary otology referral institutions.

Subjects and Methods

Patients undergoing surgery for AN. Univariate and multivariate analysis of association between BMI and complications was performed using two-tailed t tests and binary logistic regression.

Results

BMI ranged from 18.0 kg/m2 to 63.9 kg/m2 with mean of 29.2 kg/m2 among 362 included patients. High BMI was associated with increased risk of cerebrospinal fluid (CSF) leak ( p = 0.003) and need for revision surgery within 6 months ( p = 0.03). CSF leak occurred in 11.6% of obese patients (BMI ≥ 30.0) and 5.1% of patients with BMI < 30.0. There was no association between BMI and post-operative intracranial hemorrhage, wound infection, or incomplete resection ( p > 0.05). Multivariate analysis revealed BMI was associated with CSF leak (odds ratio 1.11 per BMI point, p = 0.002) and need for revision surgery (odds ratio 1.07 per BMI point, p = 0.02) independent of age, gender, tumor size, or surgical approach.

Conclusions

The largest series to date investigating BMI in acoustic surgery is presented. Elevated BMI is strongly associated with CSF leak and need for revision surgery but not with other complications. Obese or overweight patients undergoing acoustic neuroma resection should be counseled of their increased risk of CSF leak.

Bone Sandwich Closure Technique for Posterior Fossa Craniectomy

Background  Surgery of posterior fossa including cerebellopontine (CP) angle involves either craniectomy or craniotomy. While there has been precedence of craniotomy in recent practice, the preferred access in resource-strapped centers still remains been craniectomy. Although the latter offers an excellent exposure, it is believed to carry increased risk of postoperative pseudomeningocoele and cerebrospinal fluid (CSF) leak compared with craniotomy. Methods  We have suggested a technique by which after standard craniectomy for the posterior fossa surgeries the bony defect is covered by Gelfoam bone sandwich (GBS) technique. We studied this technique over a period of 25.6 years in 1,028 patients. Results and Conclusion  We analyze the risk of pseudomeningocoele and CSF leak in our patients using GBS technique and reviewed literature to compare our outcomes with standard craniotomy and craniectomy procedures.

Face-to-face four hand technique in vestibular schwannoma surgery: results from 256 Danish patients with larger tumors

BACKGROUND

The objective of this study was to investigate the clinical outcome after microsurgical treatment of vestibular schwannomas using face-to-face four hand technique in 256 Danish patients treated in the Department of Neurosurgery at the Copenhagen University Hospital from 2009 to 2018.

METHODS

Data were retrospectively collected from patient records.

RESULTS

The mean tumor size was 30.6 mm and approximately 46% of the patients had tumors >30 mm. In around 1/3 of the patients a retrosigmoid approach was used and in 2/3 a translabyrinthine. In 50% of the patients, the tumor was completely removed, and in 38%, only smaller remnants were left to preserve facial function. The median operative time was approximately 2.5 h for retrosigmoid approach, and for translabyrinthine approach, it was around 3.5 h. One year after surgery, 84% of the patients had a good facial nerve function (House-Brackmann grade 1-2). In tumors ≤ 30 mm approximately 89% preserved good facial function, whereas this was only the case for around 78% of the patients with tumors > 30 mm. In 60% of the patients who had poor facial nerve function at hospital discharge, the function improved to good facial function within the 1 year follow-up period. Four patients died within 30 days after surgery, and 6% underwent reoperation for cerebrospinal fluid leakage.

CONCLUSION

Surgery for vestibular schwannomas using face-to-face four hand technique may reduce operative time and can be performed with lower risk and excellent facial nerve outcome. The risk of surgery increases with increasing tumor size.

Pseudo-Cerebrospinal Fluid Leaks of the Anterior Skull Base: Algorithm for Diagnosis and Management

Objective  Pseudo-cerebrospinal fluid (CSF) leaks are a rare cause of unilateral, watery rhinorrhea. We proposed a step-wise approach to evaluate these cases. Design  It involves a single-center retrospective cohort study. Setting  The setting is that of a tertiary academic medical center. Participants  Ten patients with diagnosis of pseudo-CSF leak over a 21-year period were evaluated using our proposed algorithm that includes computed tomography, magnetic resonance imaging, nasal endoscopy, β-2 transferrin, intrathecal fluorescein, and surgical exploration of the anterior cranial base. Main Outcome Measures  The occurrence of intracranial infection and resolution of the symptoms were evaluated at a mean follow-up of 94.4 months. Results  Eight patients had history of skull base fracture or surgery. In all patients computed tomography, magnetic resonance imaging, and nasal endoscopy did not show signs of CSF leak. Beta-2 transferrin testing was performed in five patients, being negative in all of them. Intrathecal fluorescein was performed in seven patients, being negative in five and inconclusive in two. Surgical exploration was performed in five patients, definitively ruling out CSF leak. Six patients were treated with intranasal ipratropium, resolving the symptoms in all cases. Conclusion  The presented algorithm provides a step-wise approach for patients with unilateral watery rhinorrhea, allowing to safely ruling out CSF leak.

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.

Little Insights from Big Data: Cerebrospinal Fluid Leak After Skull Base Surgery and the Limitations of Database Research

BACKGROUND

Cerebrospinal fluid (CSF) leak is a frustrating complication of skull base surgery. Published methodologies using national surgical databases to assess CSF leak have not accounted for variability between skull base operations.

OBJECTIVE

Our goal was to attempt the development of a novel framework for adapting big data techniques to skull base surgery and assess the reliability of corresponding data manipulations.

METHODS

A retrospective nested case-control analysis was performed using patients from the National Surgical Quality Improvement Program (NSQIP) registry, 2012-2015. Current Procedural Terminology and International Classification of Diseases, Ninth Revision codes identified possible skull base operations, which were systematically grouped by anatomic location. Meningioma, schwannoma, pituitary adenoma, and trigeminal neuralgia (TN) were included.

RESULTS

Of 2918 patients, 84 (2.9%) were readmitted/reoperated on within 30 days for CSF leak. Operations involving the anterior fossa, both middle/posterior fossas in 1 approach, or the orbitocranial zygomatic approach were significantly associated with CSF leak, as were schwannomas and meningiomas in any location (8.5%, 3.1%, 10.2%, 4.1%, and 3.0%; all P < 0.0001). Multivariate analysis of only middle/posterior fossa lesions identified schwannoma (odds ratio [OR], 2.7; 95% confidence interval [CI], 1.3-5.6; P = 0.008), TN (OR, 5.4; 95% CI, 2-14.7; P = 0.008), chronic obstructive pulmonary disease (OR, 3.9; 95% CI, 1.1-14; P = 0.03), and increased operative time (OR, 4.0; 95% CI, 1.7-9.5; P = 0.009) as significant CSF leak risk factors.

CONCLUSIONS

Based on NSQIP data analyzed using a rational skull base/anatomic framework, risk factors for postoperative CSF leak include chronic obstructive pulmonary disease, operative time, anterior fossa meningioma, and middle/posterior fossa schwannoma or TN. Although databases such as NSQIP can be extensively manipulated to generate surrogate results that may provide limited insight, applications beyond their design should be approached carefully.

Surgical Parameters for Minimally Invasive Trans-Eustachian Tube CSF Leak Repair: A Cadaveric Study and Literature Review

BACKGROUND

Cerebrospinal fluid rhinorrhea from a lateral skull base defect refractory to spontaneous healing and/or conservative management is most commonly managed via open surgery. Approach for repair is dictated by location of the defect, which may require surgical exploration. The final common pathway is the eustachian tube (ET). Endoscopic ET obliteration via endonasal and lateral approaches is under development. Whereas ET anatomy has been studied, surgical landmarks have not been previously described or quantified. We aimed to define surgical parameters of specific utility to endoscopic ET obliteration.

METHODS

A literature review was performed of known ET anatomic parameters. Next, using a combination of endoscopic and open techniques in cadavers, we cannulated the intact ET and dissected its posterior component to define the major curvature position of the ET, defined as the genu, and quantified the relative distances through the ET lumen. The genu was targeted as a major obstacle encountered when cannulating the ET from the nasopharynx.

RESULTS

Among 10 ETs, we found an average distance of 23 ± 5 mm from the nasopharynx to the ET genu, distance of 24 ± 3 mm from the genu to the anterior aspect of the tympanic membrane and total ET length of 47 ± 4 mm.

CONCLUSIONS

Although membranous and petrous components of the ET are important to its function, the genu may be a more useful surgical landmark. Basic surgical parameters for endoscopic ET obliteration are defined.

Cerebrospinal Fluid Leak Rate after Vestibular Schwannoma Surgery via Middle Cranial Fossa Approach

Objective  Evaluate the cerebrospinal fluid (CSF) leak rate after the middle cranial fossa (MCF) approach to vestibular schwannoma (VS) resection. Design  Retrospective case series. Setting  Quaternary referral academic center. Participants  Of 161 patients undergoing the MCF approach for a variety of skull base pathologies, 66 patients underwent this approach for VS resection between 2007 and 2017. Main Outcome Measure  Postoperative CSF leak rate. Results  There were two instances of postoperative CSF leak (3.0%). Age, gender, and BMI were not significantly associated with CSF leak. In the two cases with CSF leakage, tumors were isolated to the internal auditory canal (IAC) and both underwent gross total resection. Both CSF leaks were successfully treated with lumbar drain diversion. For the 64 cases that did not have a CSF leak, 51 were isolated to the IAC, 1 was located only in the cerebellopontine angle (CPA), and 12 were located in both the IAC and CPA. 62 patients underwent gross total resection and 2 underwent near-total resection. Mean maximal tumor diameter in the CSF leak group was 4.5 mm (range: 3-6 mm) versus 10.2 mm (range: 3-19 mm) in patients with no CSF leak ( p  = 0.03). Conclusions  The MCF approach for VS resection is a valuable technique that allows for hearing preservation and total tumor resection and can be performed with a low CSF leakage rate. This rate of CSF leak is less than the reported rates in the literature in regard to both translabyrinthine and retrosigmoid approaches.

Petrous Apex Pneumatization: Influence on Postoperative Cerebellopontine Angle Tumor Cerebrospinal Fluid Fistula

OBJECTIVE

Multiple investigators have sought to identify risk factors for cerebrospinal fluid (CSF) leak following cerebellopontine angle (CPA) tumor resection. We evaluated whether pneumatization of the petrous apex (PA) is a risk factor for CSF fistula.

METHOD

We conducted a retrospective chart review at 2 major tertiary academic institutions undergoing CPA tumor resection and analyzed their respective head or temporal computed tomography (CT) scans if available.

RESULTS

A total of 91 cases were identified; 51 (64%) demonstrated PA pneumatization, and a total of 17 CSF leaks were identified. We discovered higher rates of CSF leak (25.0% vs 13.7%; P = .273) and CSF rhinorrhea (15.0% vs 5.9%; P = .174) in patients with PA pneumatization compared to those without PA pneumatization.

CONCLUSIONS

Isolated PA pneumatization may be a risk factor and communication pathway for CSF fistula. Further studies will need to be broadened across multiple institutions to draw any additional and stronger conclusions.

National Trends in Vestibular Schwannoma Surgery: Influence of Patient Characteristics on Outcomes

Objective To characterize current vestibular schwannoma (VS) surgery outcomes with a nationwide database and identify factors associated with increased complications and prolonged hospital course. Study Design Retrospective review utilizing the University HealthSystem Consortium national inpatient database. Setting US academic health centers. Subjects and Methods Data from patients undergoing VS surgery were analyzed over a 3-year time span (October 2012 to September 2015). Surgical outcomes, such as length of stay (LOS), complications, and mortality, were analyzed on the basis of race, sex, age, and comorbidities during the 30-day postoperative period. Results A total of 3697 VS surgical cases were identified. The overall mortality rate was 0.38%, and the overall complication rate was 5.3%. Advanced age significantly affected intensive care unit LOS, mortality, and complications ( P = .04). Comorbidities, including hypertension, obesity, and depression, also significantly increased complication rates ( P = .02). Sixty-eight patients (1.8%) had a history of irradiation, and they had a significantly increased LOS ( P = .03). Conclusion Modern VS surgery has a low mortality rate and a relatively low rate of complications. Several factors contribute to high complication rates, including age and comorbidities. These data will help providers in counseling patients on which treatment course might be best suited for them.

Minimally invasive endoscopic repair of refractory lateral skull base cerebrospinal fluid rhinorrhea: case report and review of the literature

Cerebrospinal fluid (CSF) leaks occur in approximately 10% of patients undergoing a translabyrinthine, retrosigmoid, or middle fossa approach for vestibular schwannoma resection. Cerebrospinal fluid rhinorrhea also results from trauma, neoplasms, and congenital defects. A high degree of difficulty in repair sometimes requires repetitive microsurgical revisions-a rate of 10% of cases is often cited. This can not only lead to morbidity but is also costly and burdensome to the health care system. In this case-based theoretical analysis, the authors summarize the literature regarding endoscopic endonasal techniques to obliterate the eustachian tube (ET) as well as compare endoscopic endonasal versus open approaches for repair. Given the results of their analysis, they recommend endoscopic endonasal ET obliteration (EEETO) as a first- or second-line technique for the repair of CSF rhinorrhea from a lateral skull base source refractory to spontaneous healing and CSF diversion. They present a case in which EEETO resolved refractory CSF rhinorrhea over a 10-month follow-up after CSF diversions, wound reexploration, revised packing of the ET via a lateral microscopic translabyrinthine approach, and the use of a vascularized flap had failed. They further summarize the literature regarding studies that describe various iterations of EEETO. By its minimally invasive nature, EEETO imposes less morbidity as well as less risk to the patient. It can be readily implemented into algorithms once CSF diversion (for example, lumbar drain) has failed, prior to considering open surgery for repair. Additional studies are warranted to further demonstrate the outcome and cost-saving benefits of EEETO as the data until now have been largely empirical yet very hopeful. The summaries and technical notes described in this paper may serve as a resource for those skull base teams faced with similar challenging and otherwise refractory CSF leaks from a lateral skull base source.

Fluoroscopy-Assisted Transnasal Onyx Occlusion of the Eustachian Tube for Lateral Skull Base Cerebrospinal Fluid Leak Repair

Objectives  To describe transnasal Eustachian tube (ET) occlusion with a liquid embolic solution for lateral skull base cerebrospinal fluid (CSF) leaks. Design  A lateral skull base CSF fistula model was developed by the authors using fresh cadaveric heads. Using a transtympanic needle, regulated pressurized pigmented saline was continuously instilled into the middle ear space and visualized endoscopically in the nasopharynx. An angioembolization catheter was then placed through the cartilaginous ET orifice just medial to the bony ET. Under endoscopic and fluoroscopic guidance, a column of liquid embolic agent was deployed into the bony ET segment up to the middle ear space. Setting  Tertiary care academic center. Participants  Cadaveric specimens. Main Outcome Measures  Cessation of CSF flow after occlusion at supraphysiologic pressures. Results  In two cadavers, a CSF fistula model was developed and endoscopic visualization of irrigant flow into the nasopharynx was confirmed. Fluoroscopy provided adequate anatomic views of the ET and middle ear, in addition to dynamic views of embolization. Cessation of flow after occlusion was successfully achieved with pressures up to 25 mm Hg, which exceeds normal physiological intracranial pressure. Conclusion  Eustachian tube occlusion with a liquid embolic solution is feasible in a novel cadaveric CSF leak model. In the future, this relatively short, straightforward procedure may become an outpatient alternative to manage intermittent or low-flow CSF fistulae following lateral skull base surgery.

Favorable Long-Term Functional Outcomes and Safety of Auditory Brainstem Implants in Nontumor Patients

BACKGROUND

Auditory brainstem implants (ABIs) were designed to restore hearing in deaf patients with auditory tumors or those unable to receive cochlear implants. Although ABIs may help some patients, their long-term outcomes have been rarely studied.

OBJECTIVE

To assess the long-term benefits and safety of ABIs in nontumor patients with sensorineural hearing loss (SNHL).

METHODS

We retrospectively reviewed the histories of 15 deaf patients (8 females, 7 males; mean age, 15.5 yr; range, 1-56 yr) who received ABIs for treatment of SNHL at our hospital from July 2008 to November 2015. These included 11 children with narrow internal auditory canals and 4 deaf adults with severe cochlear ossification. In each patient, a 12-channel ABI electrode was placed in the cochlear nucleus complex via a retrosigmoid approach. Auditory performance was evaluated using the Categories of Auditory Performance (CAP) index and sound detection and word identification tests.

RESULTS

One year after ABI placement, 13 of 15 patients showed adequate or significantly improved auditory function based on the CAP scores at the last follow-up. Generally, adult patients tended to show better CAP scores (3.50) than pediatric patients (2.15), but the difference was not significant (P = .058). Postoperative complications included electrode migration, cerebrospinal fluid leakage, nonauditory stimulation, and minor seizures without severe sequelae or mortality.

CONCLUSION

ABIs show favorable functional outcomes and long-term safety in nontumor deaf patients with limited treatment options. Collectively, our data indicate that ABIs represent an important treatment option for SNHL.

Primary Dural Closure for Retrosigmoid Approaches

Object  Primary closure of posterior fossa dura can be challenging, and postoperative cerebrospinal fluid (CSF) leaks continue to represent a common complication of the retrosigmoid approach. We describe a simple technique to allow for primary closure of the dura following retrosigmoid approaches. The incidence of CSF leaks using this method is reported.

Methods  A retrospective chart review was conducted on all cases of retrosigmoid craniotomies performed by the senior surgeon from February 2009 to February 2015. The primary outcome was development of postoperative CSF leak or pseudomeningocele. Length of stay, lesion type, and other surgical complications were also reported.

Results  Eighty-six patients underwent a retrosigmoid craniotomy during the study period. The most common indications for retrosigmoid craniotomy were microvascular decompression (58%) and tumor resection (36%). No allo- or autografts to repair the dural defect were needed, and no lumbar drains were used. No patients developed CSF otorrhea, rhinorrhea, or incisional leak postoperatively.

Conclusion  Primary dural closure is possible in retrosigmoid approaches without the use of allo- or autografts and may prevent postoperative CSF leaks when combined with other posterior fossa closure techniques. Careful attention to the handling of the dural flap is necessary to achieve this.

Hydroxyapatite bone cement for suboccipital retrosigmoid cranioplasty: A single institution case series

OBJECTIVE

To report rates of cerebrospinal fluid leak, wound infection, and other complications after repair of retrosigmoid craniotomy with hydroxyapatite bone cement.

METHODS

Retrospective case review at tertiary referral center of patients who underwent retrosigmoid craniotomy from 2013 to 2016 with hydroxyapatite cement cranioplasty.

OUTCOME MEASURES

Presence of absence of cerebrospinal fluid leak, wound infection, and other complications.

RESULTS

Twenty cases of retrosigmoid craniotomy repaired with hydroxyapatite cement were identified. Median length of follow up was 9.8months. No cases of cerebrospinal fluid leak were identified. One patient developed a wound infection which was thought to be related to a chronic inflammatory response to the implanted dural substitute. No other major complications were noted.

CONCLUSIONS

A method and case series of suboccipital retrosigmoid cranioplasty using hydroxyapatite cement and a are reported. Hydroxyapatite cement cranioplasty is a safe and effective technique for repair of retrosigmoid craniotomy defects.