Assessment of frontal lobe sagging after endoscopic endonasal transcribriform resection of anterior skull base tumors: is rigid structural reconstruction of the cranial base defect necessary?

Dural reconstruction with or without a bone graft of paranasal and anterior skullbase malignancies: Retrospective single-center analysis of 11 cases and review of literature

Introduction

The reconstruction of frontobasal defects following oncologic resections of paranasal and anterior skull base (ASB) malignancies remains challenging. Ineffective reconstruction could lead to cerebrospinal fluid leak, meningitis, and tension pneumocephalus.

Research question

Aim of this investigation was to analyse postoperative complication rates with or without bone graft for anterior skull base reconstruction.

Material and methods

In this retrospective study, we included patients following resection of paranasal and/or anterior skull base malignancies between October 2013 and December 2022. Complications were analysed with regards to the type of skull base reconstruction.

Results

Eleven patients were identified (2 female, 9 male, age (median, SD) 64 ± 14.1 years (range 38-81). There were nine cases of paranasal sinus and nasal cavity carcinomas and two cases of olfactory neuroblastomas. Overall survival was 22.5 ± 28 months (range: 5-78), progression free survival was 17.0 ± 20.3 months (range: 11-78). Bone skull base reconstruction using a split graft was performed in three cases. Postoperative complications requiring surgical intervention were seen in 33% (one tension pneumocephalus) of cases in the bone reconstruction group and 50% (three patients with cerebrospinal fluid leak, one infection) in the non-bone reconstruction group.

Discussion and conclusion

The structural reinforcement of structural bone chip grafting might provide additional support of the ASB and prevent CSF leakage or encephalocele. Especially in large (>10 cm2) bone defects of advanced sinonasal malignancies extending into the middle cranial fossa, the full armamentarium of reconstruction possibilities should be considered.

Multilayer Anterior Skull Base Reconstruction with Cortical Rib Bone Graft: Preliminary Experience

OBJECTIVE

During the past decades, different methods have been described for anterior skull base reconstruction. Regarding larger skull base defects, few investigators have described the use of bone grafts to foster support and prevent frontal lobe sagging, herniation, or falling. The aim of this study is to describe the use of a rib bone graft, which could be an option in these cases due to its rigidity and dimensions.

METHODS

We retrospectively collected preoperative, intraoperative, and postoperative data at the last follow-up of 10 patients who underwent multilayer anterior skull base reconstruction, including rib bone graft, for large anterior cranial base defects at 2 tertiary care academic hospitals.

RESULTS

Eight patients underwent endoscopic craniectomy for sinonasal malignancies, and the other two underwent transnasal endoscopic surgery for congenital meningoencephalocele. Anterior skull base defects measured on average 3.8 cm ± 0.9 SD antero-posteriorly (range 2.5-5 cm) and 2.3 ± 0.9 SD latero-laterally (range 0.9-4 cm). Multilayer reconstruction was performed in all cases, including a rib bone graft positioned as intracranial extradural layer. No patient experienced thoracic complications during the postoperative period. No side effects related to the bone graft or meningoencephalocele occurrence were reported after a mean follow-up of 8.0 ± 6.3 months.

CONCLUSIONS

The use of a cortical rib bone graft could be a safe and effective option in skull base reconstruction when managing large defects after cancer removal.

Long-term Outcomes of Non-vascularized Multilayer Fascial Closure Technique for Dural Repair in Endoscopic Transnasal Surgery: Efficacy, Durability, and Limitations

OBJECTIVE

Non-vascularized multilayer fascial closure technique (NMFCT) can be used instead of nasoseptal flap reconstruction for dural repair in endoscopic transnasal surgery (ETS); however, due to the lack of blood supply, its long-term durability and possible limitations need to be clarified.

METHODS

This was a retrospective study on patients who underwent ETS with intraoperative cerebrospinal fluid (CSF) leakage. We assessed the postoperative and delayed CSF leakage rates and the associated risk factors.

RESULTS

Among 200 ETSs with intraoperative CSF leakage, 148 (74.0%) ETSs were performed for skull base pathologies other than pituitary neuroendocrine tumor. The mean follow-up period was 34.4 months. Esposito grade 3 leakage was confirmed in 148 (74.0%) cases. NMFCT was used either with (67 [33.5%]) or without (133 [66.5%]) lumbar drainage. There were 10 cases (5.0%) of postoperative CSF leakage that necessitated reoperation. In 4 other cases (2.0%), CSF leakage was suspected but lumbar drainage alone successfully restored the condition. Multivariate logistic regression analyses revealed that posterior skull base location (P < 0.01, odds ratio 11.5, 95% CI 1.99-2.17 × 102) and craniopharyngioma pathology (P = 0.03, odds ratio 9.4, 95% CI 1.25-1.92 × 102) were significantly associated with postoperative CSF leakage. No delayed leakage occurred during the observation period except for 2 patients who underwent multiple radiotherapies.

CONCLUSIONS

NMFCT is a reasonable alternative with long-term durability, though vascularized flap may be a better choice for cases in which vascularity of the surrounding tissues is significantly impaired due to interventions including multiple radiotherapies.

Treatment of traumatic cerebrospinal fluid rhinorrhea via extended extradural anterior skull base approach

OBJECTIVE

To describe and assess the repair technique and perioperative management for cerebrospinal fluid (CSF) leak resulting from extensive anterior skull base fracture via extradural anterior skull base approach.

METHODS

This was a retrospective review conducted at the Department of Neurosurgery of the Shanghai Tenth People's Hospital from January 2015 to April 2020. Patients with traumatic CSF rhinorrhea resulting from extensive anterior skull base fracture treated surgically via extended extradural anterior skull base approach were included in this study. The data of medical and radiological records, surgical approaches, repair techniques, peritoperative management, surgical outcome and postoperative follow-up were analyzed. Surgical repair techniques were tailored to the condition of associated injuries of the scalp, bony and dura injuries and associated intracranial lesions. Patients were followed up for the outcome of CSF leak and surgical complications. Data were presented as frequency and percent.

RESULTS

Thirty-five patients were included in this series. The patients' mean age was 33 years (range 11-71 years). Eight patients were treated surgically within 2 weeks; while the other 27 patients, with prolonged or recurrent CSF rhinorrhea, received the repair surgery at 17 days to 10 years after the initial trauma. The mean overall length of follow-up was 23 months (range 3-65 months). All the patients suffered from frontobasal multiple fractures. The basic repair tenet was to achieve watertight seal of the dura. The frontal pericranial flap alone was used in 20 patients, combined with temporalis muscle and/or its facia in 10 patients. Free fascia lata graft was used instead in the rest 5 patients. No CSF leak was found in all the patients at discharge. There was no surgical mortality in this series. Bilateral anosmia was the most common complication. At follow-up, no recurrent CSF leak or meningitis occurred. No patients developed mucoceles, epidural abscess or osteomyelitis. One patient ultimately required ventriculoperitoneal shunt because of progressive hydrocephalus.

CONCLUSION

Traumatic CSF rhinorrhea associated with extensive anterior skull base fractures often requires aggressive treatment via extended intracranial extradural approach. Vascularized tissue flaps are ideal grafts for cranial base reconstruction, either alone or in combination with temporalis muscle and its fascia---fascia lata sometimes can be opted as free autologous graft. The approach is usually reserved for patients with traumatic CSF rhinorrhea in complex frontobasal injuries.

Multi-Layer Onlay Graft Using Hydroxyapatite Cement Placement without Cerebrospinal Fluid Diversion for Endoscopic Skull Base Reconstruction

Objective

The skull base reconstruction step, which prevents cerebrospinal fluid (CSF) leakage, is one of the most challenging steps in endoscopic skull base surgery (ESS). The purpose of this study was to assess the outcomes and complications of a reconstruction technique for immediate CSF leakage repair using multiple onlay grafts following ESS.

Methods

A total of 230 consecutive patients who underwent skull base reconstruction using multiple onlay grafts with fibrin sealant patch (FSP), hydroxyapatite cement (HAC), and pedicled nasoseptal flap (PNF) for high-flow CSF leakage following ESS at three institutions were enrolled. We retrospectively reviewed the medical and radiological records to analyze the preoperative features and postoperative results.

Results

The diagnoses included craniopharyngioma (46.8%), meningioma (34.0%), pituitary adenoma (5.3%), chordoma (1.6%), Rathke’s cleft cyst (1.1%) and others (n=21, 11.2%). The trans-planum/tuberculum approach (94.3%) was the most commonly adapted surgical method, followed by the trans-sellar and transclival approaches. The third ventricle was opened in 78 patients (41.5%). Lumbar CSF drainage was not performed postoperatively in any of the patients. Postoperative CSF leakage occurred in four patients (1.7%) due to technical mistakes and were repaired with the same technique. However, postoperative meningitis occurred in 13.5% (n=31) of the patients, but no microorganisms were identified. The median latency to the diagnosis of meningitis was 8 days (range, 2–38). CSF leakage was the unique risk factor for postoperative meningitis (p<0.001).

Conclusion

The use of multiple onlay grafts with FSP, HAC, and PNF is a reliable reconstruction technique that provides immediate and complete CSF leakage repair and mucosal grafting on the skull base without the need to harvest autologous tissue or perform postoperative CSF diversion. However, postoperative meningitis should be monitored carefully.

Treatment with endoscopic transnasal resection of hypothalamic pilocytic astrocytomas: a single-center experience

Backgrounds

Pilocytic astrocytomas (PAs) are World Health Organization (WHO) grade I tumors, which are relatively common, and are benign lesions in children. PAs could originate from the cerebellum, optic pathways, and third ventricular/hypothalamic region. Traditional various transcranial routes are used for hypothalamic PAs (HPAs). However, there are few studies on hypothalamic PAs treated through the endoscopic endonasal approach (EEA). This study reports the preliminary experience of the investigators and results with HPAs via expanded EEAs.

Methods

All patients with HPAs, undergone EEA in our hospital from 2017 to 2019, were retrospectively reviewed. The demographic data, clinical symptoms, complications, skull base reconstruction, prognosis, and endocrinological data were all recorded and analyzed in detail.

Results

Finally, five female patients were enrolled. The average age of patients was 28.6 ± 14.0. All patients had complaints about their menstrual disorder. One patient had severe bilateral visual impairment. Furthermore, only one patient suffered from severe headache due to acute hydrocephalus, although there were four patients with headache or dizziness. Four cases achieved gross-total resection, and one patient achieved subtotal resection. Furthermore, there was visual improvement in one patient (case 5), and postoperative worsening of vision in one patient (case 4). However, only one patient had postoperative intracranial infection. None of the patients experienced a postoperative CSF leak, and in situ bone flap (ISBF) techniques were used for two cases for skull base repair. In particular, ISBF combined with free middle turbinate mucosal flap was used for case 5. After three years of follow-up, three patients are still alive, two patients had no neurological or visual symptoms, or tumor recurrence, and one patient had severe hypothalamic dysfunction. Unfortunately, one patient died of severe postoperative hypothalamus reaction, which presented with coma, high fever, diabetes insipidus, hypernatremia and intracranial infection. The other patient died of recurrent severe pancreatitis at one year after the operation.

Conclusion

Although the data is still very limited and preliminary, EEA provides a direct approach to HPAs with acceptable prognosis in terms of tumor resection, endocrinological and visual outcomes. ISBF technique is safe and reliable for skull base reconstruction.

Management of squamous cell carcinomas of the skull-base

PURPOSE

The purpose of this review is to assess the recent evidence regarding the management of squamous cell carcinoma of the skull-base and to discuss the implications of these findings on clinical practice.

METHOD

Free text Medline and MeSH term search of publications relating to Squamous Cell Carcinoma & Skull-base and Skull base, Neoplasm respectively. Multidisciplinary clinical guidelines were also reviewed.

RESULTS

The primary search yielded a total of 271 papers which following initial review was reduced to 28. Secondary search yielded 56 papers. There were no randomised controlled trials relating to squamous cell carcinoma of the skull-base and as such this review is based on cohort studies, case series and expert opinion.

CONCLUSION

Squamous cell carcinoma (SCC) is the most common cancer occurring in the Head and Neck. Squamous cell carcinoma is also the most common cancer arising within the nose and sinuses of which skull-base squamous cell carcinoma is a rare subgroup. Evidence relating to the management and survival of skull-base SCC is based on expert opinion and. retrospective analyses Clinical examination and biopsy, imaging and a broad multidisciplinary team are key to the management of skull-base SCC. The information gathered should be used to guide informed discussion by suitably trained experts with patients regarding surgical approach, post-operative recovery and adjuvant or neoadjuvant treatments. The standard of care is currently to perform skull base resection with or without additional craniotomy, pedicled or free flap reconstruction in multiple layers and post-operative radiation (usually photons or protons). Open approaches have traditionally been the mainstay, however in certain cases endoscopic approaches can yield equivalent results and offer many advantages. Despite advances in care survival remains poor with a nearly one in five risk of nodal recurrence within two years.

ICAR: endoscopic skull-base surgery

BACKGROUND

Endoscopic skull-base surgery (ESBS) is employed in the management of diverse skull-base pathologies. Paralleling the increased utilization of ESBS, the literature in this field has expanded rapidly. However, the rarity of these diseases, the inherent challenges of surgical studies, and the continued learning curve in ESBS have resulted in significant variability in the quality of the literature. To consolidate and critically appraise the available literature, experts in skull-base surgery have produced the International Consensus Statement on Endoscopic Skull-Base Surgery (ICAR:ESBS).

METHODS

Using previously described methodology, topics spanning the breadth of ESBS were identified and assigned a literature review, evidence-based review or evidence-based review with recommendations format. Subsequently, each topic was written and then reviewed by skull-base surgeons in both neurosurgery and otolaryngology. Following this iterative review process, the ICAR:ESBS document was synthesized and reviewed by all authors for consensus.

RESULTS

The ICAR:ESBS document addresses the role of ESBS in primary cerebrospinal fluid (CSF) rhinorrhea, intradural tumors, benign skull-base and orbital pathology, sinonasal malignancies, and clival lesions. Additionally, specific challenges in ESBS including endoscopic reconstruction and complication management were evaluated.

CONCLUSION

A critical review of the literature in ESBS demonstrates at least the equivalency of ESBS with alternative approaches in pathologies such as CSF rhinorrhea and pituitary adenoma as well as improved reconstructive techniques in reducing CSF leaks. Evidence-based recommendations are limited in other pathologies and these significant knowledge gaps call upon the skull-base community to embrace these opportunities and collaboratively address these shortcomings.

Reconstruction of skull base bone defects using an in situ bone flap after endoscopic endonasal transplanum-transtuberculum approaches

PURPOSE

The creation of bone flaps which can be later repositioned and fixed in situ for repairing the bone defects during the endoscopic endonasal approaches (EEAs)-similar to transcranial craniotomies-is still a challenge. We present an in situ bone flap (ISBF) closure for the repair of bone defects after endoscopic endonasal transplanum-transtuberculum approaches (EETAs).

METHODS

A retrospective analysis of consecutive patients who underwent the EETAs between January 2016 and February 2019 was performed. According to whether or not to use ISBF for skull base reconstruction, these patients were divided into the ISBF group or the non-ISBF group.

RESULTS

Of 47 patients in the ISBF group, only one patient (2.1%) developed postoperative cerebrospinal fluid (CSF) leakage, yielding a significantly lower leakage rate in the ISBF group than in the non-ISBF group (6 of 38, 15.8%, P = 0.042). Besides, when only comparing cases of hydrocephalus in the two groups, the CSF leakage rate in the ISBF group was 8.3% (1/12), which was still significantly lower than that in the non-ISBF group (62.5%, 6/8) (P = 0.018). Postoperative CSF leakages in both groups were successfully treated with lumbar drainage alone, and no cases of injury to the internal carotid arteries or optic nerves occurred in either group.

CONCLUSIONS

An ISBF closure similar to transcranial craniotomies with repositioning bone flap in situ-is feasible, safe, and reliable. The ISBF closure combining with a pedicled nasoseptal flap (PNSF) provides the cranial base surgeon with an additional repair method that has demonstrated effectiveness at facilitating a more stable and durable reconstruction and reducing CSF leaks.

Endoscopic Resection of Pediatric Skull Base Tumors: An Evidence-Based Review

Objectives  To perform a systematic review examining experiences with endoscopic resection of skull base lesions in the pediatric population, with a focus on outcomes, recurrence, and surgical morbidities. Methods  PubMed/MEDLINE, Cochrane Library, Embase, and Web of Science databases were evaluated. Studies were assessed for level of evidence. Bias risk was evaluated using the Cochrane Bias tool, Grades of Recommendation, Assessment, Development and Evaluation (GRADE), and Methodological Index for Non-Randomized Studies (MINORS) criteria. Patient characteristics, pathology, site of primary disease, presenting symptoms, stage, procedure specific details, and complications were evaluated. Results were reported using the Preferred Reporting Systems for Systematic Reviews and Meta-Analysis guidelines. Results  Ninety-three studies met criteria for inclusion, encompassing 574 patients with skull base tumors. The GRADE and MINORS criteria determined the overall evidence to be moderate quality. The most common benign and malignant pathologies included juvenile nasopharyngeal angiofibromas ( n  = 239) and chondrosarcomas ( n  = 11) at 41.6 and 1.9%, respectively. Of all juvenile nasopharyngeal angiofibroma tumors, most presented at stage IIIa and IIIb (25.8 and 27.3%, respectively). Nasal obstruction (16.5%) and headache (16.0%) were common symptoms at initial presentation. Surgical approaches included endoscopic endonasal ( n  = 193, 41.2%) and endoscopic extended transsphenoidal ( n  = 155, 33.1%). Early (< 6 weeks) and late (>6 weeks) complications included cerebrospinal fluid leak ( n  = 36, 17.3%) and endocrinopathy ( n  = 43, 20.7%). Mean follow-up time was 37 months (0.5-180 months), with 86.5% showing no evidence of disease and 2.1% having died from disease at last follow-up. Conclusion  Endoscopic skull base surgery has been shown to be a safe and effective method of treating a variety of pediatric skull base tumors. If appropriately employed, the minimally invasive approach can provide optimal results in the pediatric population.

Delayed complications from expanded endonasal surgery for intracranial tumors

PURPOSE OF REVIEW

Delayed complications after endoscopic endonasal approaches to the skull base, defined as complications greater than 1 month postoperatively, are uncommon. These complications are divided into categories including sinonasal, neuroanatomic, endocrine and vascular. This review highlights the most up-to-date advancements and reviews the management of delayed complications for skull base patients.

RECENT FINDINGS

Over the last 10 years, the field of endoscopic endonasal skull base surgery has expanded with new data highlighting the long-term patient outcomes. The majority of patients experience increased quality of life (QOL) after these interventions. However, delayed complications including alterations to sinonasal function, delayed encephaloceles from the bony skull base defect and resulting endocrinopathies can significantly impact patient's QOL. Awareness of these complications and their current management is valuable for endoscopic surgeons.

SUMMARY

Endonasal approaches to the skull base are safe and well tolerated in properly selected patients. This article highlights the delayed complications that require recognition and management by skull base surgeons to ensure the best possible care for patients.

Relaxing Sphenoidal Slit Incision to Extend the Anterior and Posterior Reach of Pedicled Nasoseptal Flaps During Endoscopic Skull Base Reconstruction of Transcribriform Defects: Technical Note and Results in 20 Patients

BACKGROUND

Reconstruction of large anterior skull base (ASB) defects after an endoscopic endonasal transcribriform approach (EEA-TC) remains a challenge despite the advent of the vascularized pedicled nasoseptal flap (PNSF).

OBJECTIVE

We describe a relaxing PNSF slit incision that extends the anterior and posterior reach of the PNSF to maximize tensionless flap coverage of transcribriform ASB defects.

METHODS

A retrospective chart review was conducted on 20 consecutive patients who underwent endoscopic endonasal transcribriform approach and subsequent PNSF reconstruction with a relaxing slit incision. At the time of endoscopic ASB reconstruction, the PNSF is rotated into position so that the anterior margin of the flap is situated at the posterior table of the frontal sinus. A relaxing slit incision is made across the sphenoidal segment of the PNSF, which is the segment of flap that bridges across the sphenoid sinus once the flap is rotated into position. The anterior reach of the flap is increased to adequately cover the posterior table of the frontal sinus, and the redundant sphenoidal flap is rotated posteriorly to make contact to the bony planum sphenoidale.

RESULTS

No patients developed postoperative cerebrospinal fluid leaks (0%). The ASB repair was monitored via postoperative outpatient nasal endoscopy at various time points, which demonstrated excellent mucosalization of the ASB with a mean follow-up of 19.2 months (range: 4.1-36.2 months).

CONCLUSIONS

Our simple relaxing slit incision in the sphenoidal portion of the PNSF allows for maximal tensionless coverage of extensive transcribriform defects by increasing the anterior and posterior reach of the flap.

Potential Effect of Leukocyte-Platelet-Rich Fibrin in Bone Healing of Skull Base: A Pilot Study

Background

Reconstruction of surgical defects following cranial base surgery is challenging. Others have demonstrated that leukocyte-platelet-rich fibrin (L-PRF) stimulates tissue healing and bone regeneration. However, these studies have addressed mostly maxillofacial surgical wounds.

Objective

The objective of this study was to assess the possible adjuvant role of L-PRF in inducing neoossification of the surgical bone defect in anterior skull base surgery.

Methods

We identified patients who had undergone an endoscopic endonasal surgery of the anterior skull base in which L-PRF membranes were used for the reconstruction of the bone defect and who were followed up with postoperative CT scans. CT findings were then correlated with baseline scans and with the CT scans of a patient who had undergone imaging and histologic analysis after maxillofacial surgery in which L-PRF was used and in which we demonstrated bone formation.

Results

Five patients fulfilled the inclusion criteria. In four patients, the CT scan demonstrated closure of the bony defect by neoosteogenesis; however, the bone appeared less dense than the surrounding normal bone. A comparison with the control patient yielded similar radiological features.

Conclusion

This case series suggests that L-PRF may induce bone healing and regeneration at the surgical site defect. Multi-institutional studies with a larger series of patients are required to confirm this possibility.

Radio-anatomical analysis of the pericranial flap "money box approach" for ventral skull base reconstruction

OBJECTIVES/HYPOTHESIS

To evaluate the versatility of the pericranial flap (PCF) to reconstruct the ventral skull base, using the frontal sinus as a gate for its passage into the sinonasal corridor "money box approach."

STUDY DESIGN

Anatomic-radiological study and case series.

METHODS

Various approaches and their respective defects (cribriform, transtuberculum, clival, and craniovertebral junction) were completed in 10 injected specimens. The PCF was introduced into the nose through the uppermost portion of the frontal sinus (money box approach). Computed tomography (CT) scans (n = 50) were used to measure the dimensions of the PCF and the skull base defects. The vertical projection of the external ear canal was used as the reference point to standardize the incisions for the PCF.

RESULTS

The surface area and maximum length of the PCF were 121.5 ± 19.4 cm² and 18.3 ± 1.3 cm, respectively. Using CT scans, we determined that to reconstruct defects secondary to transcribriform, transtuberculum, clival, and craniovertebral approaches, the PCF distal incision must be placed respectively at -3.7 ± 2.0 cm (angle -17.4 ± 8.5°), -0.2 ± 2.0 cm (angle -1.0 ± 9.3°), +5.5 ± 2.3 cm (angle +24.4 ± 9.7°), +8.4 ± 2.4 cm (angle +36.6 ± 11.5°), as related to the reference point. Skull base defects in our clinical cohort (n = 6) were completely reconstructed uneventfully with the PCF.

CONCLUSIONS

The PCF renders enough surface area to reconstruct all possible defects in the ventral and median skull base. Using the uppermost frontal sinus as a gateway into the nose (money box approach) is feasible and simple.

LEVEL OF EVIDENCE

NA. Laryngoscope, 127:2482-2489, 2017.

Management of Skull Base Defects After Surgical Resection of Sinonasal and Ventral Skull Base Malignancies

Over the past 2 decades, there has been a significant increase in the resection of larger and more complex ventral skull base malignancies. The resection of these lesions has resulted in the creation of larger and more difficult to repair skull base defects. There are many available options for ventral skull base reconstruction. Despite the variety of reconstructive options, the key objective is to eliminate any communication between the intracranial space and the sinonasal cavity. This article discusses some of the more common techniques currently used for repair of these skull base defects.

Risk factors associated with postoperative cerebrospinal fluid leak after endoscopic endonasal skull base surgery

OBJECTIVE The aim in this paper was to determine risk factors for the development of a postoperative CSF leak after an endoscopic endonasal approach (EEA) for resection of skull base tumors. METHODS A retrospective review of patients who underwent EEA for the resection of intradural pathology between January 1997 and June 2012 was performed. Basic demographic data were collected, along with patient body mass index (BMI), tumor pathology, reconstruction technique, lumbar drainage, and outcomes. RESULTS Of the 615 patients studied, 103 developed a postoperative CSF leak (16.7%). Sex and perioperative lumbar drainage did not affect CSF leakage rates. Posterior fossa tumors had the highest rate of CSF leakage (32.6%), followed by anterior skull base lesions (21.0%) and sellar/suprasellar lesions (9.9%) (p < 0.0001). There was a higher leakage rate for overweight and obese patients (BMI > 25 kg/m²) than for those with a healthy-weight BMI (18.7% vs 11.5%; p = 0.04). Patients in whom a pedicled vascularized flap was used for reconstruction had a lower leakage rate than those in whom a free graft was used (13.5% vs 27.8%; p = 0.0015). In patients with a BMI > 25 kg/m², the use of a pedicled flap reduced the rate of CSF leakage from 29.5% to 15.0% (p = 0.001); in patients of normal weight, this reduction did not reach statistical significance (21.9% [pedicled flap] vs 9.2% [free graft]; p = 0.09). CONCLUSIONS Preoperative BMI > 25 kg/m² and tumor location in the posterior fossa were associated with higher rates of postoperative CSF leak. Use of a pedicled vascularized flap may be associated with reduced risk of a CSF leak, particularly in overweight patients.

Osseous Repair in Minimally Invasive Reconstruction of Anterior Skull Base Defects

Management of anterior skull base defects is an area of continued innovation for skull base surgeons. Various grafting materials have been advocated for the repair of skull base defects depending on needs, availability, harvest site morbidity, and surgeon preference. Spontaneous bony closure of small skull defects is known to occur in animal models without bone grafts, but this phenomenon has been unexplored in the human skull base. The objective of this study was to evaluate osseous skull base closure in patients undergoing endoscopic repair of skull base defects. A retrospective review was performed on 13 patients who underwent endoscopic repair of skull base defects with free bone grafts who were followed with postoperative computed tomography scans. This cohort was compared to postoperative radiology from patients undergoing transsphenoidal surgery without rigid reconstruction to evaluate for spontaneous osseous closure of sellar defects. Free bone grafts are incorporated into the bony skull base in the majority of patients (84.6% with at least partial incorporation) at mean of 5.3 years postoperatively. By comparison, patients undergoing pituitary surgery did not demonstrate spontaneous osseous closure on postoperative imaging. Human anterior skull base defects do not appear to spontaneously close, even when small, suggesting that there is no "critical size defect" in the human skull base, in contrast to the robust wound healing in animal models of skull convexity and mandibular defects. Free bone grafts incorporate into the skull base over the long-term and may be utilized whenever a rigid skull base reconstruction is desired, regardless of the defect size.

Single Layer Repair of Large Anterior Skull Base Defects without Vascularized Mucosal Flap

Objectives Bilateral anterior skull base (ASB) defects following endoscopic endonasal tumor resection are most commonly repaired utilizing multilayered reconstruction with a vascularized mucosal flap. Single-layer closure of large ASB defects has been described in the literature but this technique has yet to gain a widespread use. We report our experience with a series of patients who underwent reconstruction of large ASB defects using a single-layer intradural graft, without nasoseptal flaps. We also compared the use of acellular dermal matrix (AlloDerm, LifeCell, Branchburg, New Jersey, United States) or collagen matrix xenograft (Duramatrix, Stryker, Kalamazoo, Michigan, United States) as the graft biomaterial. Design A retrospective case series. Setting Tertiary academic medical center. Main Outcome Measures Postoperative cerebrospinal fluid leak, the number of postoperative debridements, the number of postoperative infections, and time to remucosalization. Results Two patients were reconstructed with AlloDerm and three with Duramatrix, with all patients receiving postoperative external beam radiation. There were no postoperative cerebrospinal fluid leaks identified in these patients during follow-up. The AlloDerm group showed increased postsurgical crusting, the number of clinically apparent postoperative infections, and an increased time to remucosalization. Conclusions Single-layer repair without a vascularized mucosal flap is a viable method of skull base repair for large ASB defects. We found repair with Duramatrix was superior, with less graft crusting and infection, requiring fewer debridements.

Anterior Skull Base Defects Reconstructed Using Three-Layer Method: 78 Consecutive Cases with Long-Term Follow-Up

Objectives Anterior skull base defects are potentially lethal and surgical treatment must be performed as soon as possible. The purpose of this study was to evaluate whether our technique is effective or not in long-term period. Design Retrospective chart review of all patients whose data were entered into the Hospital Registry System between 1995 and 2015. Setting/Participants This study was performed at the Gaziantep University School of Medicine, Gaziantep, Turkey, in 2015 and included 78 patients who in the past 20 years underwent three-layer reconstruction surgery for anterior skull base defects at the same university. Main Outcome Measures Among the patients, defects repaired by transcranial approach had the lowest recurrence rate. Overall, successful repair was achieved in 100% of the patients. Results Pure transbasal approach was used as a single procedure on 71 (91%) patients. Combined approaches were used in seven (9%) cases. The extended transbasal approach was combined with a transfacial approach in four patients and with a pterional approach in three patients. Conclusion We encourage the use of three-layer reconstruction and recommend free fascia lata grafts and galeal flaps with vascularized pedicle as sealing material of choice in all types of cases such as tumor and trauma.

Acute Hemorrhagic Apoplectic Pituitary Adenoma: Endoscopic Management, Surgical Outcomes, and Complications

OBJECTIVE

To assess safety and effectiveness of endoscopic transsphenoidal surgery (ETS) for acute hemorrhagic apoplectic pituitary adenoma.

METHODS

Eighty nine patients with hemorrhagic apoplectic pituitary tumor undergoing endoscopic transsphenoidal surgery were included into a retrospective chart of this study. Charts were reviewed for patient age, sex, presentation, lesion size, surgical procedure, extent of resection, clinical outcome, and surgical complications.

RESULTS

Seventy eight (87.7%) patients achieved total resection, 9 (10.1%) had subtotal resection, and 2 (2.2%) patients had partial resection; no patient experienced insufficient resection. After surgery, 65 (90.3%) of 72 patients who had visual acuity deterioration preoperatively normalized and improved significantly; the rate for remission of visual field was 87.7%. All other acute symptoms, such as severe headache, nausea, vomiting, alteration of mental status, and loss of consciousness, vanished postoperatively. Twenty eight (90.4%) of 31 patients with active secreting adenoma had hormonal remission based on endocrinological evaluation. Three (3.4%) patients incurred CSF leakage which was managed with lumbar drainage. Nine (10.1%) patients incurred transient DI postoperatively, and 2 (2.2%) of them developed permanent DI. Seven (7.9%) patients developed hypopituitarism which was treated with replacement therapy of hormone. One (1.1%) experienced craniotomy for intracranial hemorrhage and died from severe surgical complications postoperatively. There were no patients of meningitis or carotid artery injury.

CONCLUSION

Early detection and emergent endoscopic transsphenoidal surgery provided a safe and effective surgical option for hemorrhagic apoplectic pituitary tumor with a low morbidity and mortality.

Endoscopic Endonasal Approach for Olfactory Groove Meningiomas: Operative Technique and Nuances

Olfactory groove meningiomas represent approximately 10% of all intracranial meningiomas. Because these tumors originate at the ventral skull base, the endonasal route provides direct access to the tumor blood supply for early devascularization and removal of the underlying hyperostotic bone at the cranial base. In carefully selected patients, these tumors can be totally removed without additional brain retraction or manipulation. In this report, we describe the surgical technique and operative nuances for removal of olfactory groove meningiomas using the endoscopic endonasal approach, and also discuss the indications, limitations, complication avoidance and management, and postoperative care.

Brain Herniation After Endoscopic Transnasal Resection of Anterior Skull Base Malignancies

BACKGROUND

Endoscopic endonasal approaches, when appropriate, allow a less invasive method to remove anterior skull base cancer than traditional external transfacial/craniofacial approaches. The resultant skull base defect can be significantly large, potentially extending from the posterior table of the frontal sinus to the tuberculum sellae in the sagittal plane, and from one lamina papyracea to the other in the coronal plane. However, frontal lobe herniation after such expanded endoscopic resection has been considered more of a theoretical than a practical occurrence.

OBJECTIVE

To report the occurrence of frontal lobe herniation into the sinonasal cavity after expanded endonasal approaches, and to analyze causes and pathogenetic mechanisms of this unusual complication, proposing how it could have been prevented.

METHODS

Two cases have been observed in 2 different skull base referral centers in the United States and Italy. Surgical and perioperative complications, postoperative course, and need for revisions were analyzed.

RESULTS

Available data support the hypothesis that this complication is not attributable to the size of the anterior skull base defect, to the surgical technique, or to the materials used for the reconstruction. We found that 1 possible contributing factor may be the presence of increased intracranial pressure associated with obesity and obstructive sleep apnea, observed in both patients.

CONCLUSION

Frontal lobe herniation must be considered as a possible, albeit rare, complication of expanded endoscopic anterior skull base resection. Preoperative investigations concerning the presence of obstructive sleep symptoms as well as proper identification of neuroimaging signs of intracranial hypertension are recommended for such cases.

Postoperative Low-Flow Cerebrospinal Fluid Leak of Endoscopic Endonasal Transsphenoidal Surgery for Pituitary Adenoma--Wait and See, or Lumbar Drain?

To assess the effectiveness of continuous lumbar drainage (LD) for management of postoperative cerebrospinal fluid leaks after endoscopic endonasal transsphenoidal approach for resection of pituitary adenoma. Three hundred eighty-four medical records of patients who were admitted to our institute during a 2.5-year period were retrospectively reviewed, 33 of them experienced low-flow cerebrospinal fluid leak postoperatively. If LD was used, all patients with low-flow cerebrospinal fluid leak were classified into 2 groups, lumbar drained group and conservatively treated group. The age, sex, management of cerebrospinal fluid leaks, and related complications were reviewed. Statistical comparisons between the 2 groups were made using SPSS 19.0 (IBM Corp, Armonk, NY). The differences were considered statistically significant if the P value was less than 0.05.Thirty-three of 384 (8.6%) experienced low-flow postoperative cerebrospinal fluid leaks. Cured rate of cerebrospinal fluid leak was 94.4% (17/18) in continuous lumbar drained group, and 93.3% (14/15) in control group. There were 2 (11.2%) patients who developed meningitis in the LD group and 1 (5.6%) patient in the control group. One patient required endoscopic repair of skull base because of persistent cerebrospinal fluid leak in both groups, with the rates of 5.6% and 6.7%, respectively. There was no significant difference noted in each rate in both groups.Placement of LD may not be necessary for the management of low-flow postoperative cerebrospinal fluid leak after using endoscopic endonasal transsphenoidal approach to pituitary adenoma.

Surgical anatomy and utility of pedicled vascularized tissue flaps for multilayered repair of skull base defects

OBJECT The objective of this study was to describe the surgical anatomy and technical nuances of various vascularized tissue flaps. METHODS The surgical anatomy of various tissue flaps and their vascular pedicles was studied in 5 colored silicone-injected anatomical specimens. Medical records were reviewed of 11 consecutive patients who underwent repair of extensive skull base defects with a combination of various vascularized flaps. RESULTS The supraorbital, supratrochlear, superficial temporal, greater auricular, and occipital arteries contribute to the vascular supply of the pericranium. The pericranial flap can be designed based on an axial blood supply. Laterally, various flaps are supplied by the deep or superficial temporal arteries. The nasoseptal flap is a vascular pedicled flap based on the nasoseptal artery. Patients with extensive skull base defects can undergo effective repair with dual flaps or triple flaps using these pedicled vascularized flaps. CONCLUSIONS Multiple pedicled flaps are available for reconstitution of the skull base. Knowledge of the surgical anatomy of these flaps is crucial for the skull base surgeon. These vascularized tissue flaps can be used effectively as single or combination flaps. Multilayered closure of cranial base defects with vascularized tissue can be used safely and may lead to excellent repair outcomes.

Treatment of cerebrospinal fluid rhinorrhea

PURPOSE OF REVIEW

Cerebrospinal fluid (CSF) rhinorrhea is a rare entity that can arise from a variety of causes. Successful management has been reported using a variety of repair techniques. The goal of this study is to make recommendations on intraoperative and postoperative management of CSF fistulas across all causes.

RECENT FINDINGS

Pooled analysis of case series reveals that free graft repairs are successful in closing most traumatic and iatrogenic CSF leaks. In contrast, multilayered, vascularized repairs are often required for large defects with high-flow leaks that communicate with a cistern and/or ventricles. Spontaneous CSF leaks are associated with idiopathic intracranial hypertension in the vast majority of cases, and when present, postoperative medical management is necessary for long-term success.

SUMMARY

Patients with CSF rhinorrhea require surgical repair to prevent life-threatening complications. Many techniques and materials are effective at achieving closure of CSF fistula across causes. Evidence suggests that patients with high-flow CSF fistulas have improved outcomes with multilayered, vascularized repairs to decrease the risk of postoperative CSF leaks. Patients with idiopathic intracranial hypertension need long-term management of the underlying disease process.

Endoscopic Endonasal Transsphenoidal Approach for Apoplectic Pituitary Tumor: Surgical Outcomes and Complications in 45 Patients

Objective To assess the safety and effectiveness of the endoscopic endonasal transsphenoidal approach (EETA) for apoplectic pituitary adenoma. Design A retrospective study. Setting Qilu Hospital of Shandong University; Brain Science Research Institute, Shandong University. Participants Patients admitted to Qilu Hospital of Shandong University who were diagnosed with an apoplectic pituitary tumor and underwent EETA for resection of the tumor. Main Outcome Measures In total 45 patients were included in a retrospective chart review. Data regarding patient age, sex, presentation, lesion size, surgical procedure, extent of resection, clinical outcome, and surgical complications were obtained from the chart review. Results In total, 38 (92.7%) of 41 patients with loss of vision obtained visual remission postoperatively. In addition, 16 patients reported a secreting adenoma, and postsurgical hormonal levels were normal or decreased in 14 patients. All other symptoms, such as headache and alteration of mental status, recovered rapidly after surgery. Two patients (4.4%) incurred cerebrospinal fluid leakage. Six patients (13.3%) experienced transient diabetes insipidus (DI) postoperatively, but none of these patients developed permanent DI. Five patients (11.1%) developed hypopituitarism and were treated with replacement of hormonal medicine. No cases of meningitis, carotid artery injury, or death related to surgery were reported. Conclusion EETA offers a safe and effective surgical option for apoplectic pituitary tumors and is associated with low morbidity and mortality.

Surgical outcomes of the endoscopic transsphenoidal route to pituitary tumours in paediatric patients >10 years of age: 5 years of experience at a single institute

OBJECTIVE

To evaluate the safety and effectiveness of the endoscopic endonasal transsphenoidal approach (EETA) for the management of pituitary adenomas in paediatric patients >10 years of age.

METHODS

A retrospective chart review was performed to identify 56 paediatric patients between 10 and 18 years of age who underwent an endonasal endoscopic transsphenoidal approach for the resection of a pituitary adenoma during the last 5 years. The age, sex, symptoms, tumour size, extent of tumour resection, clinical outcome and surgical complications of patients were reviewed.

RESULTS

Total resection was achieved in 49 (87.5%) cases, subtotal resection was achieved in 7 (12.5%) cases and no patient had a partial or insufficient resection. Of the 35 patients who experienced preoperative deterioration of vision, 33 (94.2%) achieved visual remission with rates of 34.2% and 60% for normalisation and improvement, respectively. Endocrinological normalisation was achieved in 13 (31.7%) of 41 patients who had preoperative hyperhormonal levels; hormone levels decreased in 25 (61.0%) patients, and 3 (7.3%) patients had no change in hormone level. Two (3.5%) patients incurred postoperative cerebrospinal fluid leakage, which was resolved after lumbar drainage. Four (7.1%) patients developed hypopituitarism, which required hormone therapy. Post-surgery, five (8.9%) patients incurred transient diabetes insipidus (DI), of which one (1.7%) patient developed persistent DI and was administered Minirin. Meningitis occurred in one (1.7%) patient who was cured by the administration of a third-generation antibiotic. There were no cases of intracranial haematoma, reoperation or death.

CONCLUSIONS

EETA allows neurosurgeons to safely and effectively remove paediatric pituitary adenomas with low morbidity and mortality.

Endoscopic endonasal surgery for olfactory groove meningiomas: outcomes and limitations in 50 patients

OBJECT

Recently, endoscopic endonasal surgery (EES) has been introduced in the management of skull base tumors, with constantly improving outcomes and increasing indications. The authors retrospectively reviewed the effectiveness of EES in the management of olfactory groove meningiomas.

METHODS

Between February 2003 and December 2012, 50 patients (64% female) with olfactory groove meningiomas underwent EES at the University of Pittsburgh Medical Center. The authors present the results of EES and analyze the resection rates, clinical outcome, complications, and limitations of this approach.

RESULTS

Forty-four patients presented with primary tumors, whereas six were previously treated elsewhere. The patients' mean age was 57.1 years (range 27-88 years). Clinical presentation included altered mental status (36%), visual loss (30%), headache (24%), and seizures (20%). The mean maximum tumor diameter was 41.6 mm (range 18-80 mm). All patients underwent EES, which was performed in stages in 18 giant tumors. Complete tumor resection (Simpson Grade I) was achieved in 66.7% of the 45 patients in whom it was the goal, and 13 (28.9%) had neartotal resection (> 95% of the tumor). Tumor size, calcification, and absence of cortical cuff from vasculature were significant factors that influenced the degree of resection (p = 0.002, p = 0.024, and p = 0.028, respectively). Tumor residual was usually at the most lateral and anterior tumor margins. Following EES, mental status was improved or normalized in 77.8% of the cases, vision was improved or restored in 86.7%, and headaches resolved in 83.3%. There was no postoperative deterioration of presenting symptoms. Complications were increased in tumors > 40 mm and included CSF leakage (30%), which was significantly associated with lobular tumor configuration (p = 0.048); pulmonary embolism/deep vein thrombosis, more commonly in elderly patients (20%); sinus infections (10%); and delayed abscess months or years after EES (6%). One patient had an intraoperative vascular injury resulting in transient hemiparesis (2%). There were no perioperative deaths. During a mean follow-up period of 32 months (median 22 months, range 1-115 months), 1 patient underwent repeat EES for tumor regrowth.

CONCLUSIONS

Endoscopic endonasal surgery has shown good clinical outcomes regardless of patient age, previous treatment, or tumor characteristics. Tumor size > 40 mm, calcification, and absence of cortical vascular cuff limit GTR with EES; in addition, large tumors are associated with increased postoperative complications. Significant lateral and anterior dural involvement may represent indications for using traditional craniotomies for the management of these tumors. Postoperative CSF leakage remains a problem that necessitates innovations in EES reconstruction techniques.

Updates in reconstruction of skull base defects

PURPOSE OF REVIEW

Skull base surgery has undergone a fundamental transformation with the development and rapid adoption of endoscopic endonasal expanded approaches. Defects created from these newer approaches have necessitated an evolution of novel reconstructive techniques, which are reviewed here.

RECENT FINDINGS

New reconstructive techniques continue to be developed for repairing surgical defects from endoscopic endonasal skull base resections. Improvisations also allow well known flaps to be used in these approaches. Long term outcomes from repair using some of these techniques are now becoming available.

SUMMARY

Endoscopic resection of previously unapproachable skull base lesions has become possible with advancements in technology, as well as reconstructive methods. These newer techniques may offer improved outcomes and lower morbidity over conventional surgery.

Schwannomas of the sinonasal tract and anterior skull base: a systematic review of 94 cases

BACKGROUND

Schwannomas of the anterior skull base (ASB) and sinonasal tract are extremely rare. These lesions mimic other pathologies such as olfactory groove meningiomas, hemangiopericytomas, and esthesioneuroblastomas. Because of their low incidence, ASB and sinonasal tract schwannomas have not been well characterized. A systematic review of ASB and sinonasal tract schwannomas was conducted to further elucidate the presentation and surgical management of these lesions.

METHODS

A MEDLINE/PubMed search was performed, identifying 71 articles representing 94 cases of ASB and sinonasal schwannomas. Each case was analyzed for demographics, clinical presentation, anatomic location, radiographic features, and surgical treatment.

RESULTS

In 94 patients with ASB and sinonasal schwannomas, 44 (46.8%) were exclusively sinonasal, 30 cases (31.9%) were exclusively intracranial, 12 (12.8%) were primarily intracranial with extension into the paranasal sinuses, and 8 (8.5%) were primarily sinonasal with intracranial extension. Headaches and nasal obstruction were the most common presenting symptoms occurring in 30.9 and 29.8% of cases, respectively. Magnetic resonance imaging typically showed a hyperintense mass on T2-weighted imaging (70%) and hypointense (41%) on T1-weighted imaging. Most patients underwent surgical gross total resection via craniotomy, endoscopic endonasal approach, rhinotomy, or other sinonasal approaches. Recurrence occurred in three cases ranging from 4 months to 13 years. Postoperative complications included cerebral spinal fluid leakage, bacterial meningitis, epidural hematoma, and pneumocranium.

CONCLUSION

ASB and sinonasal schwannomas are rare lesions and should be considered in the differential diagnosis of ASB masses involving the cribriform plate with sinonasal extension. Gross total resection of these lesions should be considered the goal of operative management.

Split-calvarial osteopericranial flap for reconstruction following endoscopic anterior resection of cranial base

OBJECTIVES/HYPOTHESIS

To conceive and critically evaluate an adaptation of the split calvarial osteopericranial flap for reconstruction following endoscopic endonasal resection of the anterior skull base.

STUDY DESIGN

Cadaveric anatomic study.

METHODS

Five cadavers were embalmed with methanol, and vasculature was injected with latex. Endoscopic endonasal resection of the anterior skull base was performed, followed by reconstruction with a unilateral osteopericranial flap and a contralateral conventional pericranial flap.

RESULTS

Rigid reconstruction was achieved in all specimens. Osteoplastic flap harvest was made more reliable by drilling the diploe below the graft with a curved bur. Dimensions of the bony flap were ideally shorter and wider than the defect, allowing for flap inset and rigid support by the orbits without compromise of the flap vascular supply. Endoscopic inset of the flap is feasible via nasion-frontal osteotomy and inlay technique.

CONCLUSION

Rigid anterior skull base reconstruction via split calvarial osteopericranial flap is adaptable to current endoscopic techniques. This provides more anatomic reconstruction than current methods and may lead to decreased complication rates following anterior skull base resection.

Endoscopic endonasal resection of sinonasal and anterior skull base schwannomas

Sinonasal and anterior skull base (ASB) schwannomas are rare entities. The majority of these lesions are found within the sinonasal tract, although some have intracranial extension via invasion of the ASB. Often, these tumors can be confused for other entities, especially olfactory groove meningiomas and esthesioneuroblastomas in the olfactory groove region, and juvenile nasopharyngeal angiofibromas in the infratemporal fossa. We present a single institutional series of four patients with sinonasal and ASB schwannomas that were resected purely via an endoscopic endonasal approach. A retrospective chart review was performed to identify individuals with sinonasal and/or ASB schwannomas. Demographic data, presenting symptoms, imaging, treatment, and follow-up were recorded. Two male and two female patients were included in this study. The average age was 53.5 years (range, 21 to 71). The most common presenting symptoms were facial pain and hyposmia. All tumors were treated with endoscopic endonasal resection. One patient had intradural intracranial extension and required an extended endoscopic endonasal transcribriform approach with ASB resection, while another case involving the infratemporal fossa was treated with an extended endoscopic endonasal transpterygoid approach to this region. There were no major complications at an average follow-up of 9 months (range, 0 to 16). Sinonasal and ASB schwannomas are rare entities, with often nondescript symptoms and can often mimic other types of skull base tumors. Total resection via a purely endoscopic endonasal approach can be considered for these rare neoplasms.

Early harvesting of the vascularized pedicled nasoseptal flap during endoscopic skull base surgery

PURPOSE

The vascularized pedicled nasoseptal flap (PNSF) represents a successful option for reconstruction of large skull base defects after expanded endoscopic endonasal approaches (EEA). This vascularized flap can be harvested early or late in the operation depending on the anticipation of high-flow CSF leaks. Each harvesting technique (early vs. late) is associated with different advantages and disadvantages. In this study, we evaluate our experience with early harvesting of the PNSF for repair of large skull base defects after EEA.

METHODS

A retrospective review was performed at a tertiary care medical center on patients who underwent early PNSF harvesting during reconstruction of intraoperative high-flow CSF leaks after EEA between December 2008 and March 2012. Demographic data, repair materials, surgical approach, and incidence of PNSF usage were collected.

RESULTS

Eighty-seven patients meeting the inclusion criteria were identified. In 86 procedures (98.9%), the PNSF harvested at the beginning of the operation was used. In 1 case (1.1%), the PNSF was not used because a high-flow intraoperative CSF leak was not encountered. This patient had recurrence of intradural disease 8months later, and the previously elevated PNSF was subsequent used after tumor resection.

CONCLUSION

Based on our data, a high-flow CSF leak and need for a PNSF can be accurately anticipated in patients undergoing EEA for skull base lesions. Because of the advantages of early harvesting of the PNSF and the high preoperative predictive value of CSF leak anticipations, this technique represents a feasible harvesting practice for EEA surgeries.