Endoscopic skull base surgery for sinonasal malignancy

Long-term outcomes in advanced anterior skull base malignancy: a single quaternary institution experience

BACKGROUND

Advanced skull base malignancies are a heterogenous subset of head and neck cancers, and management is often complex. In recent times, there has been a paradigm shift in surgical technique and the advent of novel systemic options. Our goal was to analyse the long-term outcomes of a single quaternary head and neck and skull base service.

METHODS

A retrospective review of 127 patients with advanced anterior skull base malignancies that were treated at our institution between 1999 and 2015 was performed. Multiple variables were investigated to assess their significance on 5 and 10-year outcomes.

RESULTS

The mean age was 60.9 (± 12.6 SD). Sixty-four percent were males and 36% were females. Ninety percent of patients had T4 disease. Median survival time was 133 months. The 5-year overall survival (OS) was 66.2%, disease-specific survival (DSS) was 74.7%, and recurrence-free survival (RFS) was 65.0%. The 10-year OS was 55.1%, DSS was 72.1%, and RFS was 53.4%. Histological type and margin status significantly affected OS & DSS.

CONCLUSION

Surgical management of advanced skull base tumours has evolved over the last few decades at our institution with acceptable survival outcomes and complication rates. Histological diagnosis and margin status are the main predictors of survival. The addition of neoadjuvant systemic agents in current trials may improve outcomes.

Postoperative mometasone irrigations improve quality of life in skull base tumor patients

Objectives

The use of topical corticosteroids to manage postoperative sinonasal symptoms after endoscopic skull base surgery (ESBS) has not been well studied. We quantified long-term impact of postoperative steroid irrigations (SIs) on quality of life of patients after ESBS.

Methods

Retrospective review of patients at the University of Pennsylvania undergoing ESBS from 2010 to 2019. Data on patient demographics and postoperative treatment with nasal saline irrigation twice daily with and without dissolved steroids (mometasone or budesonide) was collected. Preoperative, and 1-, 3-, 6-, 12-, 18-, and 24-month postoperative Sino-Nasal Outcome Test (SNOT-22) scores were assessed.

Results

A total of 727 patients were assessed (53.4% males), with 479 patients in the no SI group and 248 patients in the SI group. Preoperative SNOT-22 scores did not differ significantly (P = 0.19). 1-, 3-, 6-, 12-, 18-, and 24-month post-op SNOT-22 scores did not significantly differ between groups. However, mometasone irrigations resulted in significantly lower postoperative 2-year SNOT-22 scores compared to budesonide (P < 0.01) and saline (P = 0.03).

Conclusions

Though corticosteroid irrigations are routine in managing inflammatory sinus disease, their role in postoperative management after ESBS for tumors is unclear. Our findings suggest that mometasone irrigation may be effective at improving postoperative quality of life in patients after ESBS.

Prognostic factors and outcomes in minimal access resections of skull base and sinonasal epithelial malignancy

BACKGROUND

Sinonasal epithelial malignancies are uncommon tumours but represent a challenge to treatment given their close proximity to the orbit, brain and cranial nerves. Traditional external surgical approaches have potential for significant functional and cosmetic morbidity. An endoscopic approach provides the surgeon with good access for tumour removal and enables surveillance postoperatively. This study aimed to assess outcomes of an endoscopic approach to sinonasal epithelial malignancy and evaluate factors that may influence its utility.

METHODS

A case series was performed involving consecutive patients treated with endoscopic or endoscopic-assisted surgery for epithelial sinonasal malignancy. Stratification included TNM staging, histopathology, surgical approach, margin status, perineural involvement and adjuvant or neoadjuvant therapy. At follow-up, complications, local control, nodal status and evidence of distant metastases were recorded. Statistical analyses to identify risk factors for developing recurrence and survival differences were performed.

RESULTS

Thirty-five patients were assessed in this study (59.2 ± 11.4 years, 42.9% female). T stage at presentation was T1 in 11.4%, T2 in 17.1%, T3 in 22.9% and T4 in 48.6%. The 3 and 5 year disease specific survival were 91.3% (SE 5) and 71.1% (SE 10). The only factors to influence survival outcomes were perineural invasion of tumour and positive margins at the time of initial surgery. Large tumours did not limit the utility of an endoscopic approach.

CONCLUSION

Endoscopic approach is a safe and oncologically equitable treatment approach to external approaches in the management of epithelial sinonasal malignancy. As with external approaches, perineural invasion of malignance is a poor prognostic factor.

Sinonasal cancer in Denmark 2008-2015: a population-based phase-4 cohort study from DAHANCA

BACKGROUND

Sinonasal cancer is considered a rare disease with poor survival. Its treatment has changed profoundly in recent years, primarily following the introduction of intensity-modulated radiation therapy (IMRT) and minimally invasive endoscopic surgery. Danish national guidelines on treatment of patients diagnosed with sinonasal carcinoma were introduced in 2007. The aim of this phase-4 study was to assess the effect of the implementation of guidelines by describing treatment outcomes in a consecutive nationwide cohort.

METHODS

All patients diagnosed with sinonasal carcinoma in Denmark from 2008 to 2015 were identified in the nationwide clinical database, DAHANCA, and were followed until May 2020. Overall survival (OS) was analysed using Kaplan-Meier estimator. Cumulative incidence of locoregional failure (LRF) and disease-specific mortality (DSM) were analysed using the Aalen-Johansen estimator. Competing risks were death from other causes (DSM) and distant failure and death (LRF). Analysis of prognostic factors was performed using Cox proportional hazard analysis. Start of follow-up was time of diagnosis. The results are presented as estimates with 95% confidence intervals (95% CIs).

RESULTS

A total of 331 patients were identified. Curatively intended treatment was performed in 264 patients (80%). Non-compliance with treatment guidelines was registered in 24 patients (9%). Non-compliance was associated with LRF (hazard ratio [HR], 2.0 [95% CI: 1.1-3.5]). Among patients qualified for curative treatment, failure occurred in 109 patients (41%), primarily at the primary tumour site (81%). Anatomical tumour site and disease stage were independent prognostic factors. The 5-year OS was 56% in patients treated with curative intent, and a combined treatment strategy showed reduced LRF (HR, 0.53 [95% CI: 0.30-0.92]) in a multivariate analysis.

CONCLUSIONS

Guideline compliance and a combined treatment approach reduced the incidence of LRF and thereby increased OS. Our results confirm those of international studies. Treatment of sinonasal carcinoma remains a challenge that requires multidisciplinary team coordination.

Infratemporal fossa surgical approaches to primary/recurrent malignancies of salivary origin: paradigm surgical shift, patient selection, and oncologic outcomes

PURPOSE OF REVIEW

To review, the surgical approaches available on diagnosing a patient with salivary gland malignancy in the infratemporal fossa (ITF). To comment on patient evaluation and method of treatment selection. To identify and report on patient outcome data and make recommendations on future needs.

RECENT FINDINGS

There is a need to define the anatomic boundaries contents of the ITF, masticator space, parapharyngeal space (PPS), pterygopalatine fossa, ventral skull base, and paramedian skull base, as evidence from publications. The pathological subtypes identified mainly include adenoid cystic and mucoepidermoid carcinomas. The source of these tumours originates from primary disease in the sinonasal tract and nasopharynx superiorly, and the PPS/deep lobe of parotid inferiorly. Current surgical options available, in suitable selected patient, available in tertiary head and neck cancer hospitals, which have available facilities and staffing is the endoscopic endonasal approach. This approach offers patients a 'complete margin-free surgical excision', minimal complications, shorter hospital stay, and no delay with commencement of any adjuvant treatment compared with the traditional 'open transcutaneous' approach.

SUMMARY

The current evidence specifically to the surgical management of salivary gland malignancy involving the ITF is sparse, with great difficult identifying treated patients and their details among a heterogeneous group of patients with many lesions. There is a need for patient data that have specific pathologic conditions to be amalgamated from such centers and publish on outcome events.

The endoscopic endonasal approach for sinonasal and nasopharyngeal adenoid cystic carcinoma

OBJECTIVE

To determine factors affecting outcomes for patients with sinonasal and nasopharyngeal adenoid cystic carcinoma (SNACC) treated using the endoscopic endonasal approach (EEA) with preservation of key structures followed by adjuvant radiotherapy (RT).

METHOD

Retrospective case series of 30 patients treated at the University of Pittsburgh between 2000 and 2014. Hospital records were reviewed for clinical and pathologic data. Outcome measures included overall survival (OS), disease-free survival (DFS), local recurrence-free survival (LRFS) and distant metastasis-free survival (DMFS) rates.

RESULTS

The majority of patients had T4a and T4b disease (23.3%, and 63.3%). Microscopically positive margins were present in 21 patients (63.6%). Positive margins were present in nine patients (30.0%). The mean and median follow-up were 3.97 and 3.29 years. Five-year OS, DFS, LRFS, and DMFS were 62.66%, 58.45%, 87.54%, and 65.26%. High-/intermediate-grade tumors had worse DFS (P = .023), and LRFS (P = .026) (HR = 4.837, 95% CI, 1.181-19.812). No factors were associated with significantly worse DMFS. No patient suffered CSF leak, optic nerve, or internal carotid injury. The mean and median length of hospital stay was 4.1 days and 2.0 days (range: 0-32 days).

CONCLUSION

Organ-preserving EEA with adjuvant RT for low-grade SNACC offers 5-year survival similar to that reported by other studies, which include radical, open skull base surgery. Patients with high-grade disease do poorly and may benefit from novel treatment strategies. For low-grade disease, organ-preserving EEA with RT may be the best option, offering a balance of survival, quality of life, and decreased morbidity for patients with this difficult-to-cure disease.

LEVEL OF EVIDENCE

4 Laryngoscope, 130:1414-1421, 2020.

Validation of training levels in endoscopic endonasal surgery of the skull base

OBJECTIVE

A five-level training program was first proposed 10 years ago for surgeons learning endoscopic endonasal surgery (EES) of the skull base. Levels were based on the complexity of anatomy, risk of neurovascular injury, intradural dissection, technical difficulty and vascularity of tumors.

METHOD

A three-phase validation concept is proposed: 1) face validity (the classification is related to clinically significant elements), 2) construct validity (the classification predicts the outcome), and 3) inter-team validation (the classification applies to other surgical teams). Consecutive cases over a 1-year time span were retrospectively classified. Primary outcome measures included: complication rates (cranial nerve injury, stroke and vascular injury, cerebrospinal fluid [CSF] leak and infection), estimated blood loss and duration of surgery.

RESULTS

Two hundred and nine consecutive cases were analyzed. The distribution of cases for each category was: 63 cases in level II, 70 cases in level III, 66 cases in level IV, and 10 cases in level V. Construct validity demonstrated statistical difference with increasing rate of complications from level II to level III and from level III to level IV; also, specific rates of cranial nerve injury and CSF leak increased between levels III and IV. Face validity identified 162 citations since publication of the original article. Inter-team validation demonstrated no difference between two teams of surgeons.

CONCLUSION

This study provides a three-phase validation of training levels for endoscopic skull base surgery. Adoption of a progressive systematic approach to learning EES from least complex to advanced procedures is expected to minimize the risks while surgical teams gain experience.

LEVEL OF EVIDENCE

3 Laryngoscope, 129:2253-2257, 2019.

Rhinology-specific priority setting for quality improvement: a modified Delphi study from the Quality Improvement Committee of the American Rhinologic Society

BACKGROUND

Improving the quality of healthcare is a complex and resource intensive process. To optimize the allocation of scarce resources, quality improvement (QI) should focus on high-value diseases that will produce the largest improvement in health system performance. Given the breadth and multidisciplinary nature of sinonasal disease management, the purpose of this study was to transparently develop a prioritized list of sinonasal diseases for QI from the perspective of the specialty of rhinology and the American Rhinologic Society (ARS).

METHODS

The RAND modified Delphi methodology was used to rank the priority of nine sinonasal disease categories from 1 (lowest priority) to 9 (highest priority). Two rounds of ranking along with a teleconference meeting was performed by a panel of 9 experts from the ARS Quality Improvement Committee.

RESULTS

The final QI-prioritized list of sinonasal diseases are as follows: chronic rhinosinusitis (CRS) (mean score = 8.9), recurrent acute rhinosinusitis (RARS) (mean score = 7.9), sinonasal neoplasms (mean score = 7.0), anatomic nasal obstruction (mean score = 5.9), refractory epistaxis (mean score = 5.2), complicated acute rhinosinusitis (mean score = 5.2), chronic nonallergic rhinitis (mean score = 4.4), orbital disease (mean score = 4.3), uncomplicated acute rhinosinusitis (mean score = 4.1), and allergy/allergic rhinitis (mean score = 3.7).

CONCLUSION

The three most important disease categories for QI from the perspective of the specialty of rhinology were CRS, RARS, and sinonasal neoplasms. Future studies need to define and validate quality metrics for each of these important disease categories in order to facilitate appropriate measurement and improvement initiatives.

Sinonasal Malignancies of Anterior Skull Base: Histology-driven Treatment Strategies

The advances in endoscopy have revolutionized the management of sinonasal and skull base lesions. Many complex cancers that traditionally required open approaches are now amenable to purely endoscopic endonasal resection, providing less invasive surgery with lower morbidity but with comparable oncologic outcomes in terms of survival rates. This article discusses the current evidence for the multimodal management of sinonasal and anterior skull base cancers focusing on the different treatment protocols driven by histologic subtypes.

Imaging in Endoscopic Cranial Skull Base and Pituitary Surgery

Endoscopic endonasal approaches have widely accepted techniques for managing benign and malignant processes along the entire ventral skull base with similar or better results compared with open procedures, but with lower rates of complication. Managing pathology affecting the skull base can be challenging because of complex anatomy and the proximity of critical neurovascular structures. Postoperative imaging can be challenging, because of surgical alterations of normal anatomy and the now common use of complex reconstruction techniques. Understanding the normal imaging appearance of skull base reconstruction is important for accurate postoperative interpretation and delineation between normal reconstructive tissue and recurrent neoplasm.

Syndrome of inappropriate antidiuretic hormone secretion associated with olfactory neuroblastoma

This study reports a patient having olfactory neuroblastoma complicated by syndrome of inappropriate antidiuretic hormone secretion. Olfactory neuroblastoma is a rare tumor that begins in the olfactory membrane. Only 10 cases have been reported previously. Because of having nonspecific symptoms, most patients manifest at an advanced stage at the time of diagnosis. Olfactory neuroblastoma may show local invasion and/or distant metastasis. We demonstrated preoperatively clinical and biochemical parameters consistent with antidiuretic hormone syndrome turned to normal ranges after the treatment. Surgery, chemotherapy, and radiotherapy are the choices of treatment; among these, surgery is an indispensible treatment.

Surgical Techniques for Sinonasal Malignancies

Sinonasal malignancies are a rare subset of malignancies of the upper aerodigestive tract which had been traditionally approached via open techniques. This article primarily addresses a paradigm shift in endoscopic endonasal oncological resection utilizing principles of tumor disassembly and negative margins. The surgical steps to these endoscopic techniques are detailed, emphasizing principles of sound oncological resection.

Postoperative irrigation therapy after sinonasal tumor surgery

BACKGROUND

Sinonasal care after endoscopic tumor resection aims to manage crusting, edema, mucus, and a healing cavity. High-volume irrigations have proved beneficial in this setting. The addition of corticosteroid to the irrigation is used for chronic rhinosinusitis (CRS) in modifying the postsurgical inflammatory response; however, its effect in endoscopic sinonasal tumor resection is unknown. Saline alone versus combination saline and corticosteroid irrigations in postoperative nasal care of sinonasal tumor patients was assessed.

METHODS

A retrospective cohort of patients postendoscopic endonasal tumor resection was assessed. Patients used 240 mL of saline or 240 mL of saline with 1 mg of betamethasone daily. Nasal symptom scores (NSSs) and the 22-item Sino-Nasal Outcome test (SNOT-22) was recorded 3 months postoperatively. An endoscopic score was made of the area undergoing secondary healing at 3 months by two blinded assessors.

RESULTS

Fifty-nine patients were assessed (aged 50.1 ± 18.26 years; 36% female subjects). The groups were similar in number (saline n = 31), treatment, and surgical characteristics. The endoscopic scores did not differ between the groups at 3 months. NSS was lower in the saline group (1.0 [interquartile range {IQR}, 3] versus 7.0 [IQR, 9]; p = 0.03) and, similarly, for SNOT-22 (0.24 [IQR, 1] versus 1.09 [IQR, 1]; p = 0.01) compared with the saline with steroid group.

CONCLUSION

Although corticosteroid irrigations have become routine for managing inflammatory sinus disease at our center, their use after tumor surgery does not appear to be warranted. The inflammatory healing process after tumor surgery differs from CRS inflammation and may explain the observed findings.

Endoscopic endonasal surgery for malignancies of the anterior cranial base

OBJECTIVE

Data from several centers worldwide have demonstrated that transnasal endoscopic surgery performed with or without a transcranial approach is capable of achieving radical resection of selected sinonasal malignancies. We report our experience with endoscopic management of sinonasal cancers, with emphasis on naso-ethmoidal malignancies encroaching on the anterior skull base.

METHODS

Major series reporting results concerning the endoscopic endonasal approach with or without craniectomy for treatment of sinonasal and anterior skull base cancers were reviewed. Preoperative work-up, indications and exclusion criteria, surgical techniques, postoperative management, and adjuvant therapy are reported.

RESULTS

In the 2 largest series analyzed, the most common malignancies were adenocarcinoma (28%), olfactory neuroblastoma (14.5%), and squamous cell carcinoma (13.5%). The 5-year disease-specific survival rate ranged from 81.9%-87%, with no major differences in the mean follow-up time (34.1 months vs. 37 months).

CONCLUSIONS

Endoscopic endonasal resection performed with or without a transcranial approach, when properly planned and in expert hands, has an accepted role with precise indications in the surgeon's armamentarium for the treatment of sinonasal and skull base malignancies.

MR imaging evolution of endoscopic cranial defect reconstructions using nasoseptal flaps and their distinction from neoplasm

BACKGROUND AND PURPOSE

Endoscopic endonasal approach is the procedure of choice for the resection of ventral skull base neoplasms, with defect closure requiring multilayer reconstruction. This study evaluates the temporal MR imaging evolution of nasoseptal flaps and free grafts used in endoscopic skull base reconstruction.

MATERIALS AND METHODS

Sixty-nine follow-up brain MRIs of 22 patients who had endoscopic skull base reconstruction using 26 nasoseptal flaps combined with 8 collagen-matrix dural grafts, 10 fascia lata grafts, and 10 intracranial fat grafts were retrospectively reviewed. Temporal changes in signal intensity, enhancement, thickness, and the configuration of reconstructive layers were evaluated. Tissue with signal intensity or enhancement different from that of normal evolving reconstructive layers at the surgical bed was evaluated, and its association with clinically confirmed tumor was assessed with the Fisher exact test.

RESULTS

All normal reconstructive layers were retracted to cranial defects and showed maturation of imaging features within 2-6 months. The immediate postoperative T2-isointensity to brain and enhancement of nasoseptal flaps persisted, but the flap thickness was reduced by 20%-30% (average thickness, 4.5 ± 1.3 mm); additionally, the C shape and vascular pedicle of the nasoseptal flaps became indistinct, but the flap location remained unchanged. The initial appearance of the nonenhancing fascia lata with variable T2 signal intensity became enhancing with increasing T2-hypointensity and a graft-thickness reduction of ≥50% (average thickness, 3.5 ± 1.6 mm). All fat grafts showed progressive resorption. In 6 patients, abnormal tissue represented residual or recurrent tumor (P = .0001).

CONCLUSIONS

Maturation and stability of multilayer endoscopic skull base reconstructions on MR imaging occurs within 2-6 months postoperatively. Understanding of the normal imaging evolution of endoscopic skull base reconstructions is essential to distinguish them from neoplasms.

Quality of life following endoscopic endonasal resection of anterior skull base cancers

OBJECT

For several decades, the exclusive purpose in the management of anterior skull base malignancies has been to increase survival rates. Recently, given the improved prognosis achieved, more attention has been focused on quality of life (QOL) as well. Producing data on QOL in anterior skull base cancers is hampered by the rarity of the neoplasm and the lack of specific questionnaires. The purpose of this study was to assess health-related QOL in a large and homogeneous cohort of patients affected by anterior skull base cancers who had undergone endoscopic endonasal resection.

METHODS

The authors conducted a retrospective review of patients treated for sinonasal and skull base cancers via an endoscopic endonasal approach at two Italian tertiary care referral centers. All patients were asked to complete the Anterior Skull Base Surgery Questionnaire to evaluate their QOL before and 1 month and 1 year after surgical treatment. To assess which parameters affect QOL, the study population was divided into subgroups according to age, sex, stage of disease, surgical approach, and adjuvant therapy.

RESULTS

One hundred fifty-three patients were enrolled in this study according to the adopted inclusion criteria. Overall QOL started at a score of 4.68 for the preoperative period, sharply decreased as far as a score of 4.03 during the 1st postoperative month, and rose again to a score of 4.59 over the course of 1 year after treatment, with a significant difference among the 3 values (p < 0.05). The specific symptoms and physical status domains registered poorer results at the 1-year assessment (4.00 and 4.71, respectively) than at the preoperative assessment (both domains 4.86), with a statistically significant reduction in scores (p < 0.05). Worse outcomes were associated with several variables: age > 60 years (difference of 0.21 points between the preoperative and 1-year period, p < 0.05), expanded surgical approaches with transnasal craniectomy (decrease of 0.20 points between the preoperative and 1-year period, p < 0.05), and postoperative radiotherapy (score of 4.53 at the 1-year period vs. 4.70 in patients without any adjuvant treatment, p < 0.05). No statistically significant differences were found when analyzing the study population according to sex (p > 0.1) and T classification of disease at presentation (p > 0.05).

CONCLUSIONS

Radical endoscopic endonasal resection led to either complete or at least partial recovery of patient QOL within the 1st postoperative year.

The risk of meningitis following expanded endoscopic endonasal skull base surgery: a systematic review

Objective To examine the risk of postoperative meningitis following expanded endoscopic endonasal skull base (EESB) surgery. Setting A systematic analysis of publications identified through searches of the electronic databases from Embase (1980-July 17, 2012), Medline (1950-July 17, 2012), and references of review articles. Main Outcome Measures Incidence of meningitis following EESB surgery. Results A total of 2,444 manuscripts were selected initially, and full-text analysis produced 67 studies with extractable data. Fifty-two contained data regarding the frequency of postoperative meningitis. The overall risk of postoperative meningitis following EESB surgery was 1.8% (36 of 2,005). For those reporting a cerebrospinal fluid (CSF) leak, meningitis occurred in 13.0% (35 of 269). For those not reporting a CSF leak, meningitis occurred in 0.1% (1 of 1,736). The odds ratio for the development of meningitis in the presence of a postoperative CSF leak was 91.99 (95% confidence interval, 11.72-721.88; p < 0.01). There was no difference in reported incidence of meningitis or CSF leak between anterior and posterior cranial fossa surgery. There was one reported case of meningitis-related mortality following EESB surgery. Conclusion The evidence in skull base surgery is limited. This study demonstrates a low incidence of meningitis (1.8%) following EESB procedures. The incidence of meningitis from EESB surgery without an associated CSF leak is uncommon.

Evidence-based practice: endoscopic skull base resection for malignancy

Successful outcomes of endoscopic approaches to benign sinonasal tumors have launched interest in expanding its use for sinonasal malignancy. Because of the heterogeneity and rarity of sinonasal malignancy, evidence for clinical outcomes of endoscopic approaches versus traditional craniofacial resection is low. Using the Oxford Center for Evidence-based Medicine guidelines, we present the existing evidence comparing both techniques for a variety of sinonasal malignancies.

A systematic review of published evidence on expanded endoscopic endonasal skull base surgery and the risk of postoperative seizure

Although postoperative seizure is an acknowledged risk following transcranial surgery, the incidence of seizure after removal of intradural pathology via an expanded endoscopic endonasal approach is not well defined. The current study was performed to systematically review the risk of seizure in patients undergoing endoscopic endonasal skull base (EESB) surgery. Embase (1980 to 9 March 2012) and Medline (1950 to 9 March 2012) were searched using a search strategy designed to include any studies that report the perioperative outcomes following EESB surgery. Outcomes of patients undergoing a simple closure of cerebrospinal fluid fistulae or encephaloceles and transellar approaches for pituitary or intrasellar lesions were excluded because this review is focused on large skull base defects. A title search selected those articles relevant to clinical series on expanded endoscopic approaches. A subsequent search of abstracts selected for manuscripts of any report that documented the presence or absence of postoperative seizure. A total of 2234 manuscripts were selected initially and full text analysis produced 67 studies with extractable data regarding the perioperative outcomes for EESB surgery. Of these manuscripts, seven reported the incidence of seizure following EESB procedures. Two of these studies were excluded due to duplication of authorship and institutional data. The overall risk of postoperative seizure following EESB surgery was estimated at 1.1% (six of 530). Subgroup analyses of data revealed that the risk of seizure following an endoscopic endonasal to the anterior cranial base was 2.3% (one patient of 43). For a posterior cranial base approach, the risk of seizure was indeterminate due to deficiency of reporting in the current literature. We concluded that the risk of seizure following an EESB procedure appears to be low (1%). However, the lack of reporting on the incidence of seizures or the use of antiepileptic prophylaxis following EESB procedure is a key limitation. Future EESB studies will need to include seizure as an outcome to accurately define this risk.