Pneumocephalus patterns following endonasal endoscopic skull base surgery as predictors of postoperative CSF leaks

Multimodal diagnosis of cerebrospinal fluid rhinorrhea: State of the art review and emerging concepts

Objective

Currently, diagnosis of cerebrospinal fluid (CSF) rhinorrhea relies on a multimodal approach, increasing costs and ultimately delaying diagnosis. In the United States and internationally, the crux of such a diagnosis relies on confirmation testing (via biomarkers) and localization (e.g., imaging). Biomarker testing may require analysis at an outside facility, resulting in delays diagnosis and treatment. In addition, specialized imaging may be nonspecific and often requires an active leak for diagnosis. There remains a clear need for innovative new technology.

Methods

A comprehensive review was conducted on both foundational and innovative scholarly articles regarding current and emerging diagnosis modalities for CSF.

Results

Current modalities in CSF rhinorrhea diagnosis and localization include laboratory tests (namely, B2T immunofixation), imaging (CT and/or MRI) with or without intrathecal administration, and surgical exploration. Each of these modalities carry flaws, risks, and benefits, ultimately contributing to delays in diagnosis and morbidity. Promising emerging technologies include lateral flow immunoassays (LFI) and biologically functionalized field-effect transistors (BioFET). Nevertheless, these carry some drawbacks of their own, and require further validation.

Conclusion

CSF rhinorrhea remains a challenging diagnosis, requiring a multimodal approach to differentiate from nonpathologic causes of rhinorrhea. Current methods in diagnosis are imperfect, as the ideal test would be a readily accessible, inexpensive, rapid, highly accurate point-of-care test without the need for excess fluid or specialized processing. Critical work is being done to develop promising, new, improved tests, though a clear successor has not yet emerged.

Level of Evidence

N/A.

Using Ipratropium Bromide Nasal Spray Response as a Screening Tool in the Diagnostic Workup of Cerebrospinal Fluid Rhinorrhea

OBJECTIVES

Unilateral clear thin rhinorrhea (UCTR) can be concerning for a nasal cerebrospinal fluid (CSF) leak. Beta-2 transferrin electrophoresis has been the gold standard for initial non-invasive confirmatory testing for CSF rhinorrhea, but there can be issues with fluid collection and testing errors. Ipratropium bromide nasal spray (IBNS) is highly effective at reducing rhinitis-related rhinorrhea, and should presumably not resolve CSF rhinorrhea. This study assessed whether different clinical features and IBNS response helped predict presence or absence of CSF rhinorrhea.

METHODS

A prospective cohort study was conducted where all patients with UCTR had nasal fluid tested for beta-2 transferrin, and were prescribed 0.06% IBNS. Patients were diagnosed with CSF rhinorrhea or other rhinologic conditions. Clinical variables like IBNS response (rhinorrhea reduction), positional worsening, salty taste, postoperative state, female gender, and body-mass index were assessed for their ability to predict CSF rhinorrhea. Sensitivity, specificity, and predictive values and odds ratios were calculated for all clinical variables.

RESULTS

Twenty patients had CSF rhinorrhea, and 53 had non-CSF etiologies. Amongst clinical variables assessed for predicting CSF absence or presence, significant associations were shown for IBNS response (OR = 844.66, p = 0.001), positional rhinorrhea worsening (OR = 8.22, p = 0.049), and body-mass index ≥30 (OR = 2.92, p = 0.048). IBNS response demonstrated 96% sensitivity and 100% specificity, and 100% positive and 91% negative predictive values for predicting CSF rhinorrhea.

CONCLUSIONS

In patients with UCTR, 0.06% IBNS response is an excellent screening tool for excluding CSF rhinorrhea, and should be considered in the diagnostic workup of CSF rhinorrhea.

LEVEL OF EVIDENCE

2 Laryngoscope, 134:56-61, 2024.

Tension Pneumocephalus: A Potentially Fatal Complication of Expanded Endoscopic Endonasal Approach

While some volume of pneumocephalus occurs following any surgery entailing dural breach, tension pneumocephalus (TP) is a rare complication of endoscopic endonasal surgery described in less than 1% cases including expanded endoscopic endonasal approaches (EEEA). It is a neurosurgical emergency warranting urgent decompression. Two cases, who developed TP following EEEA are presented. One had sinonasal malignancy (adenoid cystic carcinoma) eroding the anterior skull-base (T4N0M0) and the other was a large olfactory groove meningioma. TP was heralded in both by sudden deterioration in neurological status. Both cases underwent bifrontal craniotomy for decompression with simultaneous skull-base repair incorporating a vascularised pericranial flap. Brief literature review regarding the pathophysiology, contributing factors, diagnosis, management, and prevention of TP following EEEA is presented. TP, a life-threatening neurosurgical emergency, warrants meticulous precautions for its prevention, and vigilant postoperative monitoring for early detection. Urgent decompression with thorough skull-base repair is imperative to prevent complications.

Exploration of the causes of cerebrospinal fluid leakage after endoscopic endonasal surgery for sellar and suprasellar lesions and analysis of risk factors

Objective

Postoperative cerebrospinal fluid (CSF) leakage following endoscopic endonasal surgery (EES) is a frequent complication. This study aims to identify potential risk factors of postoperative CSF leakage.

Methods

A retrospective review of 360 patients who underwent EES was included. The associations between postoperative CSF leakage and patient demographics, medical history, tumor characteristics, and intraoperative repair techniques were analyzed; the diagnosis and repair of postoperative CSF leakage were also introduced.

Results

Postoperative CSF leakage occurred in 14 patients (3.9%), 2 of them cured by lumbar cistern drainage, 12 underwent endoscopic repair. Among these 12 cases, 3 were repaired twice, and the rest were cured the first time. During the repair surgery, insufficient embedded fat was detected in one case detected, seven with breached inner artificial dura, three had vascularized pedicle nasoseptal flap (VP-NSF) displacement, two with VP-NSF perforation, two with VP-NSF inactivation, and one with imperfect adherence to VP-NSF to the skull base. Eight cases had intracranial infections. Excluding one case who died of severe intracranial infection, the rest were cured and discharged without obvious sequelae. Multivariate analysis revealed that the suprasellar lesion, subarachnoid invasion, and intraoperative grade 3 flow CSF leakage were the risk factors of CSF leakage after operation, while the bone flap was a protective factor.

Conclusion

Bone flap combined with VP-NSF and iodoform gauze for skull base reconstruction is recommended in high-risk patients, while postoperative lumbar cistern drain remains dispensable.

Clinical application of the “sellar barrier’s concept” for predicting intraoperative CSF leak in endoscopic endonasal surgery for pituitary adenomas with a machine learning analysis

Background

Recently, it was defined that the sellar barrier entity could be identified as a predictor of cerebrospinal fluid (CSF) intraoperative leakage. The aim of this study is to validate the application of the sellar barrier concept for predicting intraoperative CSF leak in endoscopic endonasal surgery for pituitary adenomas with a machine learning approach.

Methods

We conducted a prospective cohort study, from June 2019 to September 2020: data from 155 patients with pituitary subdiaphragmatic adenoma operated through endoscopic approach at the Division of Neurosurgery, Università degli Studi di Napoli “Federico II,” were included. Preoperative magnetic resonance images (MRI) and intraoperative findings were analyzed. After processing patient data, the experiment was conducted as a novelty detection problem, splitting outliers (i.e., patients with intraoperative fistula, n = 11/155) and inliers into separate datasets, the latter further separated into training (n = 115/144) and inlier test (n = 29/144) datasets. The machine learning analysis was performed using different novelty detection algorithms [isolation forest, local outlier factor, one-class support vector machine (oSVM)], whose performance was assessed separately and as an ensemble on the inlier and outlier test sets.

Results

According to the type of sellar barrier, patients were classified into two groups, i.e., strong and weak barrier; a third category of mixed barrier was defined when a case was neither weak nor strong. Significant differences between the three datasets were found for Knosp classification score (p = 0.0015), MRI barrier: strong (p = 1.405 × 10⁻⁶), MRI barrier: weak (p = 4.487 × 10⁻⁸), intraoperative barrier: strong (p = 2.788 × 10⁻⁷), and intraoperative barrier: weak (p = 2.191 × 10⁻¹⁰). We recorded 11 cases of intraoperative leakage that occurred in the majority of patients presenting a weak sellar barrier (p = 4.487 × 10⁻⁸) at preoperative MRI. Accuracy, sensitivity, and specificity for outlier detection were 0.70, 0.64, and 0.72 for IF; 0.85, 0.45, and 1.00 for LOF; 0.83, 0.64, and 0.90 for oSVM; and 0.83, 0.55, and 0.93 for the ensemble, respectively.

Conclusions

There is a true correlation between the type of sellar barrier at MRI and its in vivo features as observed during endoscopic endonasal surgery. The novelty detection models highlighted differences between patients who developed an intraoperative CSF leak and those who did not.

Detection of Cerebrospinal Fluid Leaks Using the Endoscopic Fluorescein Test in the Postoperative Period following Pituitary and Ventral Skull Base Surgery

Objective  Diagnosis of cerebrospinal fluid (CSF) leaks is sometimes challenging in the postoperative period following pituitary and ventral skull base surgery. Intrathecal fluorescein (ITF) may be useful in this setting. Design  Retrospective chart review. Setting  Tertiary care center. Methods and Participants  All patients who underwent pituitary and ventral skull base surgery performed by a single rhinologist between January 2017 and March 2020 were included. There were 103 patients identified. Eighteen patients received 20 ITF injections due to clinical suspicion for CSF leak during the postoperative period without florid CSF rhinorrhea on clinical exam. Computed tomography scans with new or increasing intracranial air and intraoperative findings were used to confirm CSF leaks. Clinical courses were reviewed for at least 6 months after initial concern for leak as the final determinate of CSF leak. Main Outcome Measures  Specificity and safety of ITF. Results  Eleven (61%) ITF patients were female and 7 (39%) were male. Average patient age was 52.50 ± 11.89. There were six patients with confirmed postoperative CSF leaks, 3 of whom had evaluations with ITF. ITF use resulted in 2 true positives, 1 false negative, 17 true negatives, and 0 false positives. ITF sensitivity was 67%, specificity was 100%, and positive and negative predictive values were 100 and 94.4%, respectively. There were no adverse effects from ITF use. Conclusions  Existing modalities for detecting postoperative CSF leaks suffer from suboptimal sensitivity and specificity, delayed result reporting, or limited availability. ITF represents a specific and safe test with potential utility in the postoperative setting.

Intraventricular Pneumocephalus as a Complication of Ventriculoperitoneal Shunt

Pneumocephalus is defined as the presence of air in the intracranial cavity, and this complication is rare after ventriculoperitoneal shunt (VPS) surgery. It can be caused by traumatic brain injury (TBI), surgical interventions, and anatomical or spontaneous malformation. We present a case of intraventricular pneumocephalus associated with the placement of a VPS. The patient was a 40-year-old man who had a VPS inserted 10-years ago due to hydrocephalus caused by TBI. He presented to the emergency room with complaints of headache, vomiting, rhinoliquorrhea, and fever. Computed tomography of the skull showed ventricular dilatation with intraventricular pneumocephalus. In a three-dimensional reconstruction, a bone defect was visualized with meningocele at the base of the skull that would explain the cerebrospinal fluid fistula. The meningocele was surgically corrected. After 14 days of antibiotic treatment, a new VPS was placed and the patient progressed satisfactorily. Pneumocephalus associated with VPS is a rare condition that can develop secondary to a combination of the shunt effect and an anatomical defect at the base of the skull. Excessively negative and persistent intracranial pressure of the shunt allows air to enter and fill the existing vacuum through the defect in the skull base. This bone defect may be congenital, due to traumatic brain injury, or a result of hydrocephalus itself. Computed tomography of the skull is an excellent investigation for the visualization of bone defects, and treatment involves a correction of the fistula. Pneumocephalus associated with VPS is rare. The presence of rhinoliquorrhea is a strong indication of the condition. Once the presence of a fistula is confirmed, it should be corrected to prevent worsening of the pneumocephalus.

Pneumocephalus secondary to a spinal surgery: A literature review and a case report

Introduction

We report a case of pneumocephalus, which is identified as the presence of air in the cranial cavity and is a rare complication after spinal surgeries, in addition to a literature review of similarly reported cases.

Case presentation

The patient is a 63-year-old male who developed pneumocephalus after undergoing a minimally invasive left side decompression at L3-L4 with left L4 foraminotomy even though there were no signs of dural tears or Cerebrospinal Fluid (CSF) leaks. After the diagnosis of pneumocephalus using brain Magnetic Resonance Imaging (MRI), the patient was treated conservatively and was discharged after 3 weeks without developing further complications.

Discussion

Pneumocephalus is defined as an abnormal accumulation of air within the cranial cavity. It can occur due to a variety of causes but rarely due to gas forming bacteria. Many theories are suggested concerning the pathophysiology of pneumocephalus, the inverted bottle theory, the ball valve theory, the Nitrous Oxide (N₂O) theory, and as we outweigh in our case, gas forming bacteria theory. Pneumocephalus can be treated surgically, nevertheless, conservative management methods of such cases are usually followed.

Conclusion

The aim of this study is to draw further attention to the management and diagnosis of such surgical complication. A more extended research is needed to provide a full comprehensive approach to deal with this problem if faced in the future. To the best of our knowledge, this study reports the first pneumocephalus case induced by a postoperative bacterial infection in the global English based medical literature.

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Pneumocephalus caused by gas forming infection in the spine is a rare complication after spinal surgery.

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Unexplained headache spinal surgeries should raise suspicion toward pneumocephalus.

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There are many theories regarding the development of pneumocephalus, each one need specific attention.

Failure of anterior skull base reconstruction for sinonasal carcinoma: consequence on the postoperative follow up. A multicentre evaluation of management

BACKGROUND

Numerous techniques for closure of the anterior skull base in cancer patients have a high success rate but management of failure is poorly documented.

OBJECTIVES

To standardize the post-operative follow-up after reconstruction surgery of the anterior skull base after removal for sinonasal carcinoma.

MATERIALS AND METHODS

Retrospective review of failure of anterior skull base reconstruction between 2005 and 2018 in a multicenter setting.

RESULTS

Twenty four patients were included. Reconstruction failure was detected by a cerebrospinal (CSF) leak in 79.2%, by an infectious complication without CSF leak (i.e. meningitis) in 12.5%, and in 8.3% by extensive pneumocephalus. Failure was observed during the first week after surgery in 75% of patients, in the second week in 21%, and in 4% after day 15. The delay in discovery of the failure was associated with multilayer reconstruction (p=.03). Failure was treated surgically in 54% of the patients and medically in 46%, with a similar success rate (85 vs. 100%).

CONCLUSION AND SIGNIFICANCE

After carcinologic resection of the anterior skull base, monitoring should be systematic during the first postoperative week. Surgical management of failure is not always necessary.

Skull base reconstruction: A question of flow? A critical analysis of 521 endoscopic endonasal surgeries

INTRODUCTION

Post-operative CSF leak still represents the main drawback of Endoscopic Endonasal Approach (EEA), and different reconstructive strategies have been proposed in order to decrease its rate.

OBJECTIVE

To critically analyze the effectiveness of different adopted reconstruction strategies in patients that underwent EEA.

MATERIALS AND METHODS

Adult patients with skull base tumor surgically treated with EEA were retrospectively analyzed. Data recorded for each case concerned patient demographics, type of surgical approach, histotype, anatomical site of surgical approach, intra-operative CSF leak grade (no leak (INL), low flow (ILFL), high flow (IHFL)), reconstructive adopted strategy, Lumbar Drain positioning, post-operative CSF leak rate and intra/post-operative complications.

RESULTS

A total number of 521 patients (January 2012-December 2019) was included. Intra-operative CSF leak grade showed to be associated with post-operative CSF leak rate. In particular, the risk to observe a post-operative CSF leak was higher when IHFL was encountered (25,5%; Exp(B) 16.25). In particular, vascularized multilayered reconstruction and fat use showed to be effective in lowering post-operative CSF leaks in IHFL (p 0.02). No differences were found considering INL and ILFL groups. Yearly post-operative CSF leak rate analysis showed a significative decreasing trend.

CONCLUSION

Intra-operative CSF leak grade strongly affected post-operative CSF leak rate. Multilayer reconstruction with fat and naso-septal flap could reduce the rate of CSF leak in high risk patients. Reconstructive strategies should be tailored according also to the type and the anatomical site of the approach.

Trends in cerebrospinal fluid leak rates following the extended endoscopic endonasal approach for anterior skull base meningioma: a meta-analysis over the last 20 years

OBJECTIVE

The extended endoscopic approach provides unimpaired visualization and direct access to ventral skull base pathology, but is associated with cerebrospinal fluid (CSF) leak in up to 25% of patients. To evaluate the impact of improved surgical techniques and devices to better repair skull base defects, we assessed published surgical outcomes of the extended endoscopic endonasal approach in the last two decades for a well-defined homogenous group of tuberculum sellae and olfactory groove meningioma patients.

METHODS

Random-effects meta-analyses were performed for studies published between 2004 (first publications) and April 2020. We evaluated CSF leak as primary outcome. Secondary outcomes were gross total resection, improvement in visual outcomes in those presenting with a deficit, intraoperative arterial injury, and 30-day mortality. For the main analyses, publications were pragmatically grouped based on publication year in three categories: 2004-2010, 2011-2015, and 2016-2020.

RESULTS

We included 29 studies describing 540 patients with tuberculum sellae and 115 with olfactory groove meningioma. The percentage patients with CSF leak dropped over time from 22% (95% CI: 6-43%) in studies published between 2004 and 2010, to 16% (95% CI: 11-23%) between 2011 and 2015, and 4% (95% CI: 1-9%) between 2016 and 2020. Outcomes of gross total resection, visual improvement, intraoperative arterial injury, and 30-day mortality remained stable over time CONCLUSIONS: We report a noticeable decrease in CSF leak over time, which might be attributed to the development and improvement of new closure techniques (e.g., Hadad-Bassagasteguy flap, and gasket seal), refined multilayer repair protocols, and lumbar drain usage.

Endoscopic Skull Base Repair Strategy for CSF Leaks Associated with Pneumocephalus

Background: Cerebrospinal (CSF) fluid leaks with associated pneumocephalus (PNC) represent a condition bearing serious risks for the patient, with little data available in the literature. Reported success rates of endoscopic skull base repair are lower when PNC is associated than in the case of simple CSF leaks. The present study represents an analysis of our experience with endoscopic management of this condition. Methods: Records of patients with pneumocephalus and associated CSF leaks, who underwent endoscopic skull base repair, were reviewed. Demographics, history, etiology of PNC, size of defect, surgical approach, reconstruction technique and complications were evaluated. Results: Twenty patients with CSF leaks and PNC underwent endonasal repair by the senior author between 2005 and 2019. Defect size was larger than 15 mm in all cases. All patients presented either worsening of PNC under conservative treatment or tension PNC. First-attempt closure of the defect was successful in all patients (100%), with resolution of the pneumocephalus. One patient developed a synechia in the proximity of the frontal ostium, as a postoperative complication. The mean follow-up was 39 months (range: 15–94 months). Conclusion: The present study represents a proposed argument for earlier endoscopic endonasal treatment in patients presenting CSF leaks and pneumocephalus.

Extent of Hyperostotic Bone Resection in Convexity Meningioma to Achieve Pathologically Free Margins

OBJECTIVE

Hyperostosis in meningiomas can be present in 4.5% to 44% of cases. Radical resection should include aggressive removal of invaded bone. It is not clear however to what extent bone removal should be carried to achieve pathologically free margins, especially that in many cases, there is a T2 hyperintense signal that extends beyond the hyperostotic bone. In this study we try to investigate the perimeter of tumour cells outside the visible nidus of hyperostotic bone and to what extent they are present outside this nidus. This would serve as an initial step for setting guidelines on dealing with hyperostosis in meningioma surgery.

METHODS

This is a prospective case series that included 14 patients with convexity meningiomas and hyperostosis during the period from March 2017 to August 2018 in two university hospitals. Patients demographics, clinical, imaging characteristics, intraoperative and postoperative data were collected and analysed. In all cases, all visible abnormal bone was excised bearing in mind to also include the hyperintense diploe in magnetic resonance imaging (MRI) T2 weighted images after careful preoperative assessment. To examine bony tumour invasion, five marked bone biopsies were taken from the craniotomy flap for histopathological examinations. These include one from the centre of hyperostotic nidus and the other four from the corners at a 2-cm distance from the margin of the nidus.

RESULTS

Our study included five males (35.7%) and nine females (64.3%) with a mean age of 43.75 years (33-55). Tumor site was parietal in seven cases (50%), fronto-parietal in three cases (21.4%), parieto-occipital in two cases (14.2%), frontal region in one case and bicoronal (midline) in one case. Tumour pathology revealed a World Health Organization (WHO) grade I in seven cases (50%), atypical meningioma (WHO II) in five cases (35.7%) and anaplastic meningioma (WHO III) in two cases (14.2%). In all grade I and II meningiomas, bone biopsies harvested from the nidus revealed infiltration with tumour cells while all other bone biopsies from the four corners (2 cm from nidus) were free. In cases of anaplastic meningiomas, all five biopsies were positive for tumour cells.

CONCLUSION

Removal of the gross epicentre of hyperostotic bone with the surrounding 2 cm is adequate to ensure radical excision and free bone margins in grade I and II meningiomas. Hyperintense signal change in MRI T2 weighted images, even beyond visible hypersototic areas, doesn't necessarily represent tumour invasion.

Expanded endoscopic endonasal approach for extending suprasellar and third ventricular lesions

BACKGROUND

Expanded endonasal approaches can provide direct access to the midline skull base from the anterior cranial fossa to the ventral foramen magnum. Surgical strategies of bone drilling, dural opening, and intradural dissection can determine the area of surgical exposure and instrument handling, affecting the safety of devascularizing/debulking suprasellar tumors.

METHODS

We describe an expanded endoscopic endonasal approach for suprasellar lesions, with stepwise image-guided dissections highlighting surgical pearls and pitfalls to enhance surgical safety. This article presents transnasal intra-third-ventricular anatomy from trans-tuber cinereum, and trans-lamina terminalis approaches, comparing subchiasmatic and suprachiasmatic trajectories.

CONCLUSION

The rostral extension via endoscopic endonasal transsellar-transtubercular-transplanum approaches can provide a safe and feasible route for suprasellar lesions, in subchiasmatic, suprachiasmatic, and intraventricular regions.

Resumption of Positive-Pressure Ventilation Devices for Obstructive Sleep Apnea following Transsphenoidal Surgery: An Institutional Experience of a Surgical Cohort

Objectives  Transsphenoidal surgery creates a skull base defect that may cause postoperative cerebrospinal fluid (CSF) leakage or pneumocephalus. This study reviewed the institutional experience of a pituitary center in managing patients who use positive-pressure ventilation (PPV) devices for obstructive sleep apnea (OSA) after transsphenoidal surgery, which risks disturbing the skull base repair. Design  Retrospective review. Setting  Pituitary referral center in a major metropolitan medical center. Methods  PPV was resumed at the discretion of the treatment team based on intraoperative findings and OSA severity. Perioperative complications related to resuming and withholding PPV were recorded. Participants  Transsphenoidal surgery patients with OSA using PPV devices. Main Outcome Measures  Intracranial complications before and after resuming PPV. Results  A total of 42 patients met the study criteria. Intraoperative CSF leakage was encountered and repaired in 20 (48%) patients. Overall, 38 patients resumed PPV (median: 3.5 weeks postsurgery; range: 0.14-52 weeks) and 4 patients did not resume PPV. Postoperatively, no patient experienced CSF leakage or pneumocephalus before or after resuming PPV. Four (10%) patients required temporary nocturnal supplemental oxygen at home, one patient was reintubated after a myocardial infarction, and one patient had a prolonged hospital stay due to chronic obstructive pulmonary disease exacerbation. Conclusions  Resuming PPV use after transsphenoidal surgery did not result in intracranial complications. However, delay in resuming PPV resulted in four patients requiring oxygen at home. We propose a preliminary PPV device management algorithm based on the size of the intraoperative CSF leak to facilitate future studies.

Qualitative Assessment of the Effect of Continuous Positive Airway Pressure on the Nasal Cavity

BACKGROUND

For patients with obstructive sleep apnea (OSA), there is a lack of knowledge regarding the impact of continuous positive airway pressure (CPAP) on the nasal cavity. There is a significant need for evidence-based recommendations regarding the appropriate use of CPAP following endoscopic sinus and skull base surgery.

OBJECTIVE

The goal of this study is to translate a previously developed cadaveric model for evaluating CPAP pressures in the sinonasal cavity by showing safety in vivo and quantifying the effect of positive pressurized air flow on the nasal cavity of healthy individuals where physiologic effects are at play.

METHODS

A previously validated cadaveric model using intracranial sensor catheters has proved to be a reliable technique for measuring sinonasal pressures. These sensors were placed in the nasal cavity of 18 healthy individuals. Pressure within the nose was recorded at increasing levels of CPAP.

RESULTS

Overall, nasal cavity pressure was on average 85% of delivered CPAP. The amount of pressure delivered to the nasal cavity increased as the CPAP increased. The percentage of CPAP delivered was 77% for 5 cmH₂O and increased to 89% at 20 cmH₂O. There was a significant difference in mean intranasal pressures between all the levels of CPAP except 5 cmH₂O and 8 cmH₂O (P < .001).

CONCLUSION

On average, only 85% of the pressure delivered by CPAP is transmitted to the nasal cavity. Higher CPAP pressures delivered a greater percentage of pressurized air to the nasal cavity floor. Our results are comparable to the cadaver model, which demonstrated similar pressure delivery even in the absence of anatomic factors such as lung compliance, nasal secretions, and edema. This study demonstrates the safety of using sensors in the human nasal cavity. This technology can also be utilized to evaluate the resiliency of various repair techniques for endoscopic skull base surgery with CPAP administration.

Risk factors for postoperative intracranial infections in patients with pituitary adenoma after endoscopic endonasal transsphenoidal surgery: pneumocephalus deserves further study

OBJECTIVE

The authors sought to identify the relevance between pneumocephalus and postoperative intracranial infections, as well as bacteriological characteristics and risk factors for intracranial infections, in patients with pituitary adenomas after endoscopic endonasal transsphenoidal surgery.

METHODS

In total, data from 251 consecutive patients with pituitary adenomas who underwent pure endoscopic endonasal transsphenoidal surgeries from 2014 to 2018 were reviewed for preoperative comorbidities, intraoperative techniques, and postoperative care.

RESULTS

This retrospective study found 18 cases of postoperative pneumocephalus (7.17%), 9 CNS infections (3.59%), and 12 CSF leaks (4.78%). Of the patients with pneumocephalus, 5 (27.8%) had CNS infections. In patients with CNS infections, the culture results were positive in 7 cases and negative in 2 cases. The statistical analysis suggested that pneumocephalus (maximum bubble diameter of ≥ 1 cm), diaphragmatic defects (intraoperative CSF leak, Kelly grade ≥ 1), and a postoperative CSF leak are risk factors for postoperative CNS infections.

CONCLUSIONS

In pituitary adenoma patients who underwent pure endoscopic endonasal transsphenoidal surgeries, intraoperative saddle reconstruction has a crucial role for patients with postoperative intracranial infections. Additionally, postoperative pneumocephalus plays an important role in predicting intracranial infections that must not be neglected. Therefore, neurosurgeons should pay close attention to the discovery of postoperative intracranial pneumocephalus because this factor is as important as a postoperative CSF leak. Pneumocephalus (maximum bubble diameter of ≥ 1 cm), diaphragmatic defects (an intraoperative CSF leak, Kelly grade ≥ 1), and a postoperative CSF leak were risk factors predictive of postoperative intracranial infections. In addition, it is essential that operative procedures be carefully performed to avoid diaphragmatic defects, to reduce exposure to the external environment, and to decrease patients’ suffering.

[Management of complex skull base defects accompanied by pneumocephalus]

AIM

The study aim was to analyze our own experience in treating patients with complex skull base defects accompanied by pneumocephalus and, based on the findings, to develop an optimal treatment approach for this pathology.

MATERIAL AND METHODS

We retrospectively reviewed a series of 30 patients with complex skull base defects accompanied by pneumocephalus who underwent inpatient treatment at the Burdenko Neurosurgical Institute in the period from 2001 to 2017. We analyzed demographic characteristics of patients (gender, age), clinical data (etiology, somatic and neuropsychiatric status, radiological data), and treatment aspects (conservative or surgical treatment, used approach, defect characteristics, reconstructive materials). Treatment outcomes were assessed based on analysis of changes in clinical manifestations, postoperative complications, and recurrences. The obtained data were compared to the results of literature review.

RESULTS

In the series of 30 patients with complex skull base defects accompanied by pneumocephalus, the mean age was 41 years (range, 17-68 years); there were 17 (59%) males and 13 (41%) females. Etiologically, there were 17 (59%) traumatic cases, 11 (36%) iatrogenic cases, and 2 (5%) spontaneous cases. Clinically, the patients presented with the following manifestations: psycho-neurological symptoms (41%), nasal cerebrospinal fluid (CSF) leak (36%), impaired consciousness (27%), and meningitis (23%). Eight patients with acute injuries underwent complex conservative treatment that included infusion, and anti-edema, vascular, metabolic, anticonvulsant, and antibacterial therapy. In cases of conservative treatment failure or tension pneumocephalus accompanied by abrupt worsening of the patient's condition, surgical treatment was used. A total of 24 interventions (including revision surgery) were performed in 22 patients. All patients underwent endoscopic endonasal reconstruction of complex skull base defects. Tissues used for reconstruction included the fascia lata and adipose tissue (77%), fascia lata and cartilage/bone from the nasal septum (14%), and a pedicled nasoseptal flap (9%). The success rate of reconstructive interventions was 91%. There were 2 (9%) recurrences. Postoperative complications in the form of meningitis occurred in 4 (18%) patients.

CONCLUSION

In the case of a nasal cerebrospinal leak history and worsening of the patient's condition accompanied by common cerebral and psychiatric symptoms, the development of pneumocephalus should be considered first, the early diagnosis of which will facilitate choosing the correct treatment approach. In the case of acute injury in patients with the established diagnosis of pneumocephalus caused by gas-forming infection, conservative therapy is indicated in the early period after neurosurgical interventions with opening of the meninges. Tension pneumocephalus together with a skull base bone defect (according to CT) and a nasal CSF leak history is the indication for surgical treatment. In this case, the endoscopic endonasal technique is the method of choice.

Post-operative imaging assessment of non-functioning pituitary adenomas

BACKGROUND

Non-functioning pituitary adenomas (NFAs) are the most common pituitary tumors. There is significant variability in clinical practice in terms of post-operative imaging evaluation. The objective of this manuscript is to provide an exhaustive review of published articles pertaining to the post-operative imaging evaluation of NFAs.

METHODS

The MEDLINE database was queried for studies investigating imaging for the post-operative evaluation of pituitary adenomas. From an initial search of 5589 articles, 37 articles were evaluated in detail and included in this review.

RESULTS

Magnetic resonance imaging (MRI) is the gold standard for post-operative monitoring of NFAs, although functional imaging modalities may improve identification of residual tumor in conjunction with MRI. The residual tumor can be distinguished from post-operative changes by experienced practitioners using high-resolution MRI in the immediate post-operative setting (within 1 week of surgery). However, continued imaging evolution in the appearance of residual tumor or resection cavity is expected up to 3 months post-operatively.

CONCLUSIONS

Post-operative imaging appearance of the pituitary gland, optic apparatus, and pneumocephalus patterns, correlated with the clinical outcomes. Long-term, lifetime follow-up is warranted for NFA patients who underwent surgical resection.

The use of polydioxanone plates for endoscopic skull base repair

BACKGROUND

Many reconstructive techniques and materials have been reported for repair of skull base defects after sinonasal tumor excision, cerebrospinal fluid (CSF) leaks, and coverage of denuded bone. Synthetic materials have been developed for endoscopic skull base repair to avoid donor-site morbidity. Polydioxanone plate is a bioabsorbable implant designed for nasal septal reconstruction and has the ability to retain strength for at least 10 weeks and absorbs in 6 months.

OBJECTIVES

This study aimed to describe the use of polydioxanone plates in endoscopic skull base defect and CSF leak repair, and to describe our experience with the surgical technique and postoperative management.

METHODS

This was a retrospective case series of patients who, between May 2013 and December 2015, underwent endoscopic sinus surgery and skull base repair for CSF leak or after excision of a skull base tumor by using polydioxanone plates. Patients who presented with sinonasal inflammatory disease or skull base tumors underwent endoscopic skull base repair by using polydioxanone plates in an underlay fashion and mucosal membrane grafts with or without adjuvant materials in an overlay fashion. The patients were reviewed at 6 days, 6 weeks, and 3 months after surgery. Postoperative adverse events, including CSF leak, infection, bleeding, headache, and graft failure, were recorded.

RESULTS

The cases of seven patients (five women, two men; mean age, 53.9 years) were reviewed. Five patients underwent sinonasal tumor resection and two underwent repair for CSF leak. The mean (standard deviation) defect size was 16.4 ± 11.4 mm. There was no evidence of postoperative CSF leak, and lumbar drains were not used. One patient reported transient headache and facial pressure at the 6-week follow-up visit. The surgeons' experience with polydioxanone plate placement, postoperative healing, and follow-up was satisfactory.

CONCLUSION

Polydioxanone could be used to achieve rigid repair of endoscopic skull base defects. These early results, although promising, require validation in clinical trials.

Predictors of ventricular tension pneumocephalus after posterior fossa surgery in the sitting position

BACKGROUND

Ventricular pneumocephalus is a rare but potentially life-threatening complication of cranial surgery in the sitting position.

OBJECTIVE

The objective of the study is to assess the incidence and risk factors of postoperative ventricular pneumocephalus.

METHODS

We performed a retrospective chart review of 307 consecutive patients (147 men, 160 women) treated at our institution by intracranial surgery in the sitting position from January 2010 to October 2014. Ventricular air entrapment with lack of arousal or neurologic deterioration requiring external ventriculostomy (EVD) was defined as ventricular tension pneumocephalus (VTP). Demographic variables were recorded along with radiological and clinical data. The occurrence of pneumocephalus was correlated with patient-related and surgical variables.

RESULTS

VTP was observed in 12 cases (3.9%). These patients had higher intraventricular air volumes (48.5 cm³ (CI 95% [29.06-67.86])) compared to asymptomatic patients (7.4 cm³ (CI 95% [5.43-9.48])). Opening of the fourth ventricle was the most potent predictor of VTP (OR = 34.7, CI 95% [4.4-273.5], p = 0.001). In patients undergoing no additional treatment for pneumocephalus, ventricular air volume declined to an average of 41.7% of the initial postoperative volume on postoperative day 3.

CONCLUSIONS

Entrapment of intracranial and particularly ventricular air requiring emergent EVD occurred in 3.9% cases of intracranial surgery in the sitting position. Especially the opening of the fourth ventricle was associated with the development of VTP, which should warrant particularly diligent postoperative observation of these patients. In cases without neurological symptoms, the rate of spontaneous air resorption is sufficiently high to warrant expectant management.

Lumbar Drains Decrease the Risk of Postoperative Cerebrospinal Fluid Leak Following Endonasal Endoscopic Surgery for Suprasellar Meningiomas in Patients With High Body Mass Index

BACKGROUND

Postoperative cerebrospinal fluid (CSF) leak is a persistent, albeit much less prominent, complication following endonasal endoscopic surgery. The pathology with highest risk is suprasellar meningiomas. A postoperative lumbar drain (LD) is used to decrease the risk of CSF leak but is not universally accepted.

OBJECTIVE

To compare the rates of postoperative CSF leak between patients with and without LD who underwent endonasal endoscopic surgical resection of suprasellar meningiomas.

METHODS

A consecutive series of newly diagnosed suprasellar meningiomas was drawn from a prospectively acquired database of endonasal endoscopic surgeries at our institution. An intraoperative, preresection LD was placed and left open at 5 cc/h for ∼48 h. In a subset of patients, the LD could not be placed. Rates of postoperative CSF leak were compared between patients with and without an LD.

RESULTS

Twenty-five patients underwent endonasal endoscopic surgical resection of suprasellar meningiomas. An LD could not be placed in 2 patients. There were 2 postoperative CSF leaks (8%), both of which occurred in the patients who did not have an LD (P = .0033). The average body mass index (BMI) of the patients in whom the LD could not be placed was 39.1 kg/m2, compared with 27.6 kg/m2 for those in whom the LD could be placed (P = .009). In the subgroup of obese patients (BMI &gt; 30 kg/m2), LD placement was protective against postoperative CSF leak (P = .022).

CONCLUSION

The inability to place an LD in patients with obesity is a risk factor for postoperative CSF leak. An LD may be useful to prevent postoperative CSF leak, particularly in patients with elevated BMI.

Complication Avoidance in Endoscopic Skull Base Surgery

Endoscopic endonasal approaches to the skull base pathology have developed and evolved dramatically over the past 2 decades, particularly with collaboration between neurosurgery and otolaryngology physicians. These advances have increased significantly the use of such approaches beyond just resection of pituitary adenomas, including a variety of skull base pathologies. As the field has evolved, so has our understanding of the complications accompanying endoscopic skull base surgery, as well as techniques to both avoid and manage these complications. These are discussed here.

Endoscopic Endonasal Management of Skull Base Chordomas: Surgical Technique, Nuances, and Pitfalls

Chordoma is a rare primary bone tumor derived from transformed notochord remnants. It has a local aggressive behavior and high recurrence rates. Treatment of skull base chordomas is complex and challenging. Control of the disease relies mainly on surgical excision of the tumor, sometimes followed by high-dose radiation therapy. The main surgical goal is to achieve maximal tumor removal with minimal morbidity. Development of the expanded endoscopic endonasal approach has improved surgical and prognostic results of skull base chordomas. This article highlights important aspects of approach selection, technique, and nuances of surgical management of this tumor.

Cerebrospinal fluid leaks in extended endoscopic transsphenoidal surgery: covering all the angles

Following extended endoscopic transsphenoidal approach (EETSA), cerebrospinal fluid (CSF) leak rate has been reported in the range of 5-50 %. Novel closure techniques, such as the nasoseptal flap and other multilayered repairs improved the outcomes significantly but took most of our focus. Little attention, however, was given to other aspects of the equation such as nasal support-to support the heavy weight of such repairs-and lumbar drains. These are important because they diminish the forces acting on both sides of the repair, hence covering all the angles. We reviewed data of 98 consecutive patients who underwent an EETSA between 1999 and 2014. We analyzed the rates of CSF leak throughout the years and with every modification added to our closure technique. Common pathologies encountered were invasive adenomas, meningiomas, chordomas, and craniopharyngiomas. CSF leak occurred overall in five patients (5.1 %). The nasoseptal flap decreased the rate of CSF leak but not significantly (P = 0.112), while placing a nasal trumpet to support our repair resulted in significant decrease in CSF leak rate (P = 0.0013). In the last 2 years of our series, when all modifications took place and all angles were covered, there was one leak in 35 cases (2.8 %). A protocol that covers all the angles by a good multilayered repair (regardless of its type and materials) while diminishing the forces acting on both sides of the repair leads to a minimal rate of CSF leak. No principle alone is effective individually.

Endoscopic Endonasal Repair of Spontaneous and Traumatic Cerebrospinal Fluid Rhinorrhea: A Review and Local Experience

This article presents an overview of endoscopic endonasal repair of cerebrospinal fluid (CSF) rhinorrhea. In recent years, endoscopic repair has become the standard of care for managing this condition, because it gradually replaces the traditional open transcranial approach. Discussion includes the etiologic classification of CSF rhinorrhea, management paradigm for each category, diagnosis algorithm, comprehensive description of the surgical technique, and an updated review of the literature regarding the safety and efficacy of this procedure. In addition, the authors present their experience, including 2 surgical videos demonstrating endoscopic repair of CSF rhinorrhea in 2 distinct clinical scenarios.

Risk of post-operative pneumocephalus in patients with obstructive sleep apnea undergoing transsphenoidal surgery

Patients undergoing transsphenoidal surgery (TSS) have an anterior skull base defect that limits the use of positive pressure ventilation post-operatively. Obstructive sleep apnea (OSA) can be seen in these patients and is treated with continuous positive airway pressure (CPAP). In our study we documented the incidence of pre-existing OSA and reported the incidence of diagnosed pneumocephalus and its relationship to OSA. A retrospective review was conducted from a surgical outcomes database. Electronic medical records were reviewed, with an emphasis on diagnosis of OSA and documented symptomatic pneumocephalus. A total of 324 patients underwent 349 TSS for sellar mass resection. The average body mass index of the study cohort was 32.5kg/m(2). Sixty-nine patients (21%) had documented OSA. Only 25 out of 69 (36%) had a documented post-operative CPAP plan. Out of all 349 procedures, there were two incidents of pneumocephalus diagnosed. Neither of the patients had pre-existing OSA. One in five patients in our study had pre-existing OSA. Most patients returned to CPAP use within several weeks of TSS for resection of a sellar mass. Neither of the patients with pneumocephalus had pre-existing OSA and none of the patients with early re-initiation of CPAP developed this complication. This study provides preliminary evidence that resuming CPAP early in the post-operative period might be less dangerous than previously assumed.

Postoperative Imaging and Surveillance in Large Nerve Perineural Spread

We present a review of the imaging surveillance following treatment for large nerve perineural spread in the skull base. The expected appearance and possible complications following surgery and radiotherapy are discussed. Imaging examples of the possible sites of disease recurrence are also presented.

Neuroendoscopic endonasal management of cerebrospinal fluid rhinorrhea

Neuroendoscopic endonasal approach has gained popularity in managing traumatic, spontaneous, and especially iatrogenic cerebrospinal fluid (CSF) rhinorrhea. The authors examined 8 patients presenting with CSF rhinorrhea between December 2012 and June 2014: 5 patients had iatrogenic leak, 2 patients had traumatic leak, and 1 patient had a spontaneous onset of CSF rhinorrhea. Sites of the CSF leaks were detected through computed tomographic cisternography and magnetic resonance imaging in the patients with traumatic and spontaneous leaks. All patients received neuroendoscopic endonasal surgery for the CSF leak. The largest defect was 22 mm in maximum diameter. Endoscopic supraciliary "keyhole" approach was performed in 1 patient after confirmation of a frontal sinus leak using the endoscopic endonasal approach. The success rate was 100% in the first attempt. Follow-up period ranged from 3 to 24 months, and no recurrence was reported. Identifying the leak site and choosing the appropriate surgical technique remain the most important factor in surgical success.