Cribriform plate dehiscence with encephalomeningocele revealed by recurrent meningitis: A case report.

INTRODUCTION: Meningitis is a potentially life threatening illness. It requires prompt diagnosis and treatment. Recurrent meningitis needs detailed investigations to identify the underlying cause. OBSERVATION: We report a case of recurrent pneumococcal meningitis in a 9-year-old boy with an underlying congenital skull base abnormality. Brain computed tomography (CT) scan showed no obvious skull base defects. A magnetic resonance imaging (MRI) of the brain revealed a dehiscence of the cribriform plate with encephalomeningocele. The patient underwent an endoscopic repair of the bony defect and had not developed any new infections ever since. CONCLUSION: This case highlights the need to investigate recurrent bacterial meningitis with CT scan and MRI of the brain and skull base. Repair of these congenital skull base defects are mandatory to prevent the recurrence of meningitis.

Augmentation of bone morphogenetic protein signaling in cranial neural crest cells in mice deforms skull base due to premature fusion of intersphenoidal synchondrosis.

Craniofacial anomalies (CFAs) are a diverse group of disorders affecting the shapes of the face and the head. Malformation of the cranial base in humans leads CFAs, such as midfacial hypoplasia and craniosynostosis. These patients have significant burdens associated with breathing, speaking, and chewing. Invasive surgical intervention is the current primary option to correct these structural deficiencies. Understanding molecular cellular mechanism for craniofacial development would provide novel therapeutic options for CFAs. In this study, we found that enhanced bone morphogenetic protein (BMP) signaling in cranial neural crest cells (NCCs) (P0-Cre;caBmpr1a mice) causes premature fusion of intersphenoid synchondrosis (ISS) resulting in leading to short snouts and hypertelorism. Histological analyses revealed reduction of proliferation and higher cell death in ISS at postnatal day 3. We demonstrated to prevent the premature fusion of ISS in P0-Cre;caBmpr1a mice by injecting a p53 inhibitor Pifithrin-α to the pregnant mother from E15.5 to E18.5, resulting in rescue from short snouts and hypertelorism. We further demonstrated to prevent premature fusion of cranial sutures in P0-Cre;caBmpr1a mice by injecting Pifithrin-α through E8.5 to E18.5. These results suggested that enhanced BMP-p53-induced cell death in cranial NCCs causes premature fusion of ISS and sutures in time-dependent manner.

Cranial Base Synchondrosis: Chondrocytes at the Hub.

The cranial base is formed by endochondral ossification and functions as a driver of anteroposterior cranial elongation and overall craniofacial growth. The cranial base contains the synchondroses that are composed of opposite-facing layers of resting, proliferating and hypertrophic chondrocytes with unique developmental origins, both in the neural crest and mesoderm. In humans, premature ossification of the synchondroses causes midfacial hypoplasia, which commonly presents in patients with syndromic craniosynostoses and skeletal Class III malocclusion. Major signaling pathways and transcription factors that regulate the long bone growth plate-PTHrP-Ihh, FGF, Wnt, BMP signaling and Runx2-are also involved in the cranial base synchondrosis. Here, we provide an updated overview of the cranial base synchondrosis and the cell population within, as well as its molecular regulation, and further discuss future research opportunities to understand the unique function of this craniofacial skeletal structure.

A Retrospective Study of Recurrent Bacterial Meningitis in Children: Etiology, Clinical Course, and Treatment.

Objectives: Recurrent bacterial meningitis (RBM) is a rare but life-threatening disease. This study aims to analyze the clinical features, potential causes, and therapeutic outcomes of RBM in children. Methods: This article retrospectively reviews the clinical characteristics, etiologies, and treatments in children with RBM hospitalized in Hebei children's hospital from 2012 to 2020. Results: A total of 10 children with RBM, five males and five females, were included in this study. The age of RBM in children spans from the neonatal stage to the childhood stage. The underlying illnesses were identified and classified as cerebrospinal fluid rhinorrhea (1 case), humoral immunodeficiency with Mondini dysplasia (1 case), common cavity deformity with cerebrospinal fluid ear leakage (1 case), Mondini malformations (2 cases), incomplete cochlear separation type I with a vestibular enlargement (2 cases), local inflammation of the sphenoid bone caused by cellulitis (1 case), congenital skull base defects (1 case), and congenital dermal sinus with intraspinal abscess (1 case). 6 patients chose targeted therapy for potential reasons. Conclusions: Congenital abnormalities or acquired injuries lead to intracranial communication with the outside world, which can quickly become a portal for bacterial invasion of the central nervous system, resulting in repeated infections.

Spontaneous Congenital Perilabyrinthine Cerebrospinal Fluid Fistulas.

OBJECTIVES: To report a recalcitrant spontaneous cerebrospinal fluid (CSF) fistula arising from multiple, anatomically-linked lateral skull base defects, and to review the available literature to determine optimal techniques for operative repair of congenital CSF fistulae. METHODS: A patient with recurrent episodes of otologic meningitis was found to have a patent tympanomeningeal fissure, also known as a Hyrtl's fissure, and internal auditory canal (IAC) diverticulum that communicated with the jugular bulb. A systematic review of the literature characterized all reports of spontaneous congenital perilabyrinthine CSF leaks, and all cases of Hyrtl's fissures. RESULTS: An 11-year-old female was referred for recurrent meningitis. Imaging demonstrated a fistulous connection between the middle ear and IAC diverticulum via the jugular foramen. Specifically, a Hyrtl's fissure was identified, as well as demineralized bone around the jugular bulb. Obliteration of the fissure was initially performed, and a fistula reformed 4 months later. Multifocal CSF egress in the hypotympanum was identified on re-exploration, and middle ear obliteration with external auditory canal (EAC) overclosure was performed. A systematic review of the literature demonstrated 19 cases of spontaneous congenital perilabyrinthine CSF leaks. In total, 6 cases had multiple sources of CSF leak and 2 had history suggestive of intracranial hypertension. All of these noted cases demonstrated leak recurrence. Middle ear obliteration with EAC overclosure was successful in 4 recalcitrant cases. CONCLUSIONS: Repair of spontaneous congenital perilabyrinthine CSF leaks in cases demonstrating multiple sources of egress or signs of intracranial hypertension should be approached with caution. Middle ear obliteration with EAC overclosure may provide the most definitive management option for these patients, particularly if initial attempt at primary repair is unsuccessful.

Defining the critical period of hedgehog pathway inhibitor-induced cranial base dysplasia in mice.

BACKGROUND: The hedgehog signaling pathway is critical for developmental patterning of the limb, craniofacial and axial skeleton. Disruption of this pathway in mice leads to a series of structural malformations, but the exact role and critical period of the Hh pathway in the early development of the cranial base have been rarely described. RESULTS: Embryos exposed to vismodegib from E7.5, E9.5, and E10.5 had a higher percentage of cranial base fenestra. The peak incidence of hypoplasia in sphenoid winglets and severe craniosynostosis in cranial base synchondroses was observed when vismodegib was administered between E9.5 and E10.5. Cranial base craniosynostosis results from accelerating terminal differentiation of chondrocytes and premature osteogenesis. CONCLUSIONS: We define the critical periods for the induction of cranial base deformity by vismodegib administration at a meticulous temporal resolution. Our findings suggest that the Hh pathway may play a vital role in the early development of the cranial base. This research also establishes a novel and easy-to-establish mouse model of synostosis in the cranial base using a commercially available pathway-selective inhibitor.

Spontaneous transethmoidal meningoencephalocele presenting in the form of recurrent unilateral nasal discharge: discussion of the diagnosis and endoscopic surgical management.

Meningoencephaloceles of the skull base most commonly occur as a sequela of head trauma or they can more rarely be congenital malformations. Several types of encephalocele exist depending on anatomic features and localisation. Clinical presentation and symptoms can vary. Different methods of management and repair of the concurring skull base defects have been described and ranging vary from endoscopic to open surgical approaches. We report the case of a 56-year-old Caucasian woman with the diagnosis of right sided spontaneous transethmoidal meninoencephalocele. Clinical presentation of this rare pathology, methods of diagnostic and management and its outcome are presented. Spontaneous skull base meningoencephaloceles are rare entities, without clear underlying etiologies. Multidisciplinary management is recommended. The transnasal endoscopic approach provides a wide skull base exposure with more advantages and less morbidity in comparison with the conventional open approach.

Current management of congenital anterior cranial base encephaloceles.

OBJECTIVES: Congenital encephaloceles provide unique diagnostic and reconstructive challenges for the pediatric rhinologist. The objectives of the current study were to evaluate contemporary treatment strategies for congenital encephaloceles focusing on presentation, surgical technique, and outcomes. METHODS: Multi-institutional retrospective chart review of congenital encephaloceles (2003-2019). Data regarding demographics, presenting symptoms, associated abnormalities, surgical technique, size, location, and complications were collected. RESULTS: Fourteen patients with 15 congenital encephaloceles were treated using endoscopic techniques (avg 6.0 years, range 2 months-22 years) with mean follow up of 23 months. The majority presented with nasal obstruction (n = 13); only one child had cerebrospinal fluid (CSF) rhinorrhea. Associated anomalies included nasal deformities, congenital hypopituitarism, and Morning Glory syndrome. Average encephalocele size was 2.44 cm (range 0.5-3.6 cm) with mean skull base defect size of 8.6 x 7.7 mm. Locations included the foramen cecum (n = 9), central sphenoid (n = 3), midline anterior cranial fossa (n = 1), orbital plate of frontal bone (n = 1), and ethmoid roof (n = 1). Because of favorable expansion from encephaloceles, it was unnecessary to postpone surgeries to allow nasal cavity growth. Three individuals had prior operations, including surgeries for "nasal polyp" or "adenoid cyst". Two patients had post-operative complications (meningitis and CSF leak) effectively treated with no further sequelae. CONCLUSIONS: In the current study, congenital encephaloceles in children as young as 2 months were successfully repaired using endoscopic techniques. Endoscopic approaches remain a safe and effective intervention for management of these lesions.

Incidence of anomalous canals in the base of the skull: a retrospective radio-anatomical study using cone-beam computed tomography.

PURPOSE: Several skull-base foramina including foramen meningo-orbitale, craniopharyngeal canals, canaliculus innominatus, foramen vesalius, palatovaginal canals, and canalis basalis medianus are visible on cone-beam computed tomographs. A good understanding of the anatomical variants of these foramina is important to accurately diagnose fractures, understand the paths that infections may take, and identify associated anomalies. We used cone-beam computed tomography to measure the incidences of skull-base foramen variants in a normal population. METHODS: A total of 350 subjects (200 females, 150 males, 6-30 years of age) were included. The prevalences of foramen meningo-orbitale, craniopharyngeal canals, canaliculus innominatus, foramina vesalius, palatovaginal canals, and canalis basalis medianus were evaluated by age and gender. RESULTS: Subject age ranged from 6 to 30 years (mean age ± SD = 15.1 ± 4.08). Foramen meningo-orbitale, craniopharyngeal canals, canaliculus innominatus, foramen vesalius, palatovaginal canal, and canalis basalis medianus were observed in 51 (14.6%), 19 (5.4%), 60 (17.1%), 145 (41.1%), 34 (9.7%), and 15 (4.3%) patients, respectively. CONCLUSIONS: Skull-base foramina are important clinically and radiologically. Imaging of such variants via cone-beam computed tomography is valuable for both physicians and patients. Few studies of skull-base foramina have used cone-beam computed tomography. Additional research is required for a fuller understanding of this phenomenon.

[Management of complex skull base defects accompanied by pneumocephalus]. / Taktika lecheniia defektov osnovaniia cherepa, soprovozhdaiushchikhsia pnevmotsefaliei.

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.

Association of Regional Cranial Base Deformity and Ultimate Structure in Crouzon Syndrome.

BACKGROUND: Considerable craniofacial features of Crouzon syndrome are attributed to the dysmorphology of the cranial base. As cephalometric studies have focused mainly on the facial deformity, rather than the cranial base, the underlying cause of deformity is not as well understood. Therefore, the authors compared the cranial base development of Crouzon syndrome to controls to trace the timing of deformity in the cranial base and face, to analyze their temporal correlation. METHODS: Ninety computed tomographic scans were included (Crouzon, n = 36; controls, n = 54) and divided into five age subgroups. Craniofacial cephalometric measurements were analyzed by Materialise software. RESULTS: The overall cranial base length in Crouzon syndrome compared with controls decreased 8 percent (p = 0.014) on average. The posterior cranial fossa shortening accounted for most of this reduction. The cranial base displaced with the distances from basion, sella, and ethmosphenoid to posterior nasal spine shortened by 21%, 18%, and 16%, respectively (all p < 0.01) during life. Although the cranial base angle on intracranial surface remains normal, the angles on facial surface narrowed were reduced. CONCLUSIONS: The cranial base deformity of Crouzon syndrome consists of the whole skull base and particularly anterior skull base shortening early, leading to a compensatory widened anterior skull base. However, when this widening did not compensate fully for the rapid enlargement of the brain, the posterior skull base displaced inferiorly and became kyphotic. The cranial base deformity develops sequentially anterior to posterior in a probable cascade of influence pattern. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, II.

Posterior nasoseptal flap in the reconstruction of skull base defects following endonasal surgery.

OBJECTIVE: To study the clinical outcomes of a posterior nasoseptal flap used in the endonasal reconstruction of anterior skull base defects. METHODS: The early harvested flap was used to reconstruct anterior skull base defects in patients with high-flow on-table cerebrospinal fluid leak. Post-operatively, the patients were analysed for cerebrospinal fluid leak and bleeding. RESULTS: Of the 100 patients, 87 had macro defects while 13 had micro defects. Non-secretary lesions were present in 60 patients, while secretary lesions were present in 40 patients. Cerebrospinal fluid leak was present in all the patients undergoing surgery, and the majority of them had a lumbar drain fitted. Post-operatively, two patients experienced bleeding and only two patients had a cerebrospinal fluid leak. CONCLUSION: The use of a posterior nasoseptal flap for reconstruction of the anterior skull base amongst patients with a high-flow intra-operative cerebrospinal fluid leak can help prevent post-operative cerebrospinal fluid leak. Its applicability to wide patient profiles, with respect to age, size of defect and diagnosis, make it a versatile choice for reconstruction after endonasal anterior skull base surgical procedures.

The reconstruction of skull base defects in infants using pedicled nasoseptal flap-a review of four cases.

INTRODUCTION: Benign lesions of the skull base are common in the paediatric population, and are usually congenital in aetiology. Majority of these lesions are treated transcranially exposing the patients to a number of risks. Although endoscopic endonasal surgery (EES) helps avoid many of these potential morbidities, CSF leak with its attendant complication remains a big concern. This study reports the use of the Hadad flap in the reconstruction of skull base defects in infants to prevent this problem. The study was conducted on four infants with a mean age of 7 months, who underwent repairs for CSF leaks associated with congenital lesions like meningocele or meningoencephalocele, using the Hadad flap. Of the four patients, three cases were revision cases and one was primary where the patients presented with complaints such as nasal obstruction and watery nasal discharge. Post surgery, the infants were monitored for a mean period of 23 months and no major complications or recurrent CSF drainage were observed. Minor complications that were observed include vestibulitis and crusting in the nose. The utility of the Hadad flap in the reconstruction of skull base defects in the paediatric age group has been controversial while its utility in infants has not been studied in literature so far. We report here in our series four infant patients in whom we believe that the nasal septum and the skull base will develop proportionally to each other, hence lowering the chances of a short flap and eliminating the occurrence of future complications. CONCLUSION: The nasoseptal flap is an effective and safe technique for reconstructing skull base defects in infancy. It can be concluded that this technique does not have any potential effect on septal or craniofacial growth as the flap is harvested only on one side with normal mucosal cover on the other side. There is no posterior septectomy or any form of bony or cartilaginous resection that is performed, hence avoiding any effects on bony growth. No studies have been published in literature so far and to the best of our knowledge, this is the first report describing the efficacy of the nasoseptal flap in infants.

The Magnetic Resonance Imaging Appearance of Endoscopic Endonasal Skull Base Defect Reconstruction Using Free Mucosal Graft.

OBJECTIVE: At our institution, skull base reconstruction using a free mucosal graft from the nasal cavity floor has been the standardized technique after pituitary adenoma resection via transsellar approach. In this study, the expected appearance of the reconstruction on postoperative magnetic resonance imaging (MRI) scans is described and its integrity and impact on the sinonasal cavity are assessed. METHODS: Fifty patients were selected, and their electronic medical records were reviewed for postoperative course, Sino-Nasal Outcome Test-22 (SNOT-22) scores, and nasal endoscopy reports. A total of 116 postoperative MRI scans were available to evaluate 1) the appearance and thickness of the graft, 2) the enhancement of the graft, and 3) the T2 signal in sphenoid sinus as a potential indication for inflammatory disease. RESULTS: There was no significant change in the thickness of the graft over time. Except for the 7 scans that were obtained without intravenous contrast, all scans showed enhancement of the graft. About half of the patients showed persistent T2 hyperintense signal at 12 and 24 months. However, this finding was not clinically significant, because postoperative SNOT-22 scores showed minimal sinonasal impact. CONCLUSIONS: Postoperative MRI surveillance scans showed a stable appearance of the graft that mimics the native mucosa, with enhancement through time, reflecting its robust vascularization and integration to the skull base. Although persistent T2 hyperintense signal was detected in the sphenoid sinus, clinical evidence based on nasal endoscopy reports and SNOT-22 scores indicated minimal sinonasal morbidity.

The Relationship Between Basilar Invagination and Chiari Malformation Type I: A Narrative Review.

Basilar invagination (BI) and Chiari malformation type I CM-I) are the most common adult craniovertebral junction malformations, and they are frequently associated with each other and present synchronously. The relationship between BI and CM-I has remained incompletely understood, and the choice of surgical strategy has remained controversial. This brief review focuses on the different aspects of BI and CM-I, and further discusses the relationship between these two concomitant pathologies on the basis of the concepts proposed over the last three decades.

Realignment of Basilar Invagination by C1-C2 Joint Distraction: A Modified Approach to a Paradigm Shift.

BACKGROUND: Distraction of the C1-C2 joint and maintenance thereof by introduction of spacers into the articular cavity can successfully and durably reduce basilar invagination (BI). Thus, with the adjunct of instrumented fusion and decompression, BI-induced myelopathy can be efficiently treated with a one-stage posterior approach. This intervention is technically challenging, and in this paper we describe a procedural variation to facilitate the approach. METHODS AND RESULTS: Through a description of a case of BI, the main anatomopathological alteration underlying and perpetrating the condition of BI is elucidated. A technique of realignment of BI is then described in which this alteration is specifically targeted and neutralized. The result is a single-stage posterior-only approach with decompression, C1-C2 distraction and introduction of poly(methyl methacrylate) (PMMA) into the joint cavity. Instrumented occipitocervical fusion completes the procedure. CONCLUSION: C1-C2 joint distraction is a technically demanding procedure. By providing a modification of the original technique and a detailed description of the crucial steps necessary to successfully and safely carry it out, we hope to make this excellent procedure more approachable.

Spontaneous cerebrospinal fluid rhinorrhoea with meningitis secondary to ecchordosis physaliphora.

Transclival CSF fistulae are rare. We report a 40-year-old female who presented with meningitis after a short history of CSF rhinorrhoea. The defect resulted from the rare notochordal remnant, ecchordosis physaliphora (EP), and was successfully resected and repaired endoscopically.

Normal angulation of skull base in Apert syndrome.

Apert syndrome is characterized by the severe craniofacial deformities. The subsequent process of skeletal maldevelopment is likely to be influenced by multiple interactions at several levels, at a given time. In this study, we aimed to explore the evolution of cranial basal dysmorphology and the chronology of these deformities in Apert syndrome, by objectively analyzing three-dimensional measurements. Fifty-four CT scans from unoperated patients (Apert, n = 18; control, n = 36) were included in this study, with age range from 3 days to 24 years. Before 6 months of age, Apert's anterior cranial base was widened 60%. Between 6 months and 2 years of age, the whole cranial base length, anterior cranial base length and posterior cranial base length decreased 8%, 8% and 14%, respectively. The greater sphenoid wing angle was wider by 26.0°, and continued into adulthood. The cranial base angles did not produce significant changes throughout life. The extra cranial distances synchronously and almost proportionally shortened after later infancy. The anterior and posterior cranial base length shortened at an almost proportional rate. The malformations of the skull vault are additive effects with cranial base fusion on skull length restriction, but the angulation of the skull base is virtually normal.

Anterior skull base duplication requiring delivery via EXIT procedure: A case report.

Duplication of the anterior skull base structures is an extremely rare malformation of failed midline blastogenesis. We present the case of a child with an obstructive oral cavity mass diagnosed on prenatal imaging. The child was successfully delivered by EXIT procedure, a tracheotomy was performed, and postnatal imaging demonstrated an array of craniofacial malformations, including complete duplication of the maxilla, pituitary glands, aqueducts of Sylvius, and basilar arteries. The child underwent excision of the duplicate maxilla, resulting in a wide cleft palate that will be repaired at a future date.

Skull base anatomy and surgical safety in isolated and CHARGE-associated bilateral choanal atresia.

INTRODUCTION: Bilateral choanal atresia (BCA) is associated with a high incidence of congenital abnormalities that include skull base anomalies and defects. Surgical repair of BCA is necessary in the early neonatal period and any altered anatomy of the adjacent skull base will heighten the risk of intracranial injury. This risk may be further increased in patients with CHARGE syndrome. OBJECTIVES: To measure surgically relevant nasal and skull base dimensions in neonates with BCA in order to determine whether any difference exists between isolated and CHARGE syndrome associated subgroups, thereby optimizing the safety of surgical repair. METHODS: A retrospective review of medical charts and computed tomography was undertaken at a tertiary pediatric hospital of all neonates diagnosed with BCA between 2004 and 2016. Isolated and CHARGE syndrome subgroups of BCA were identified from clinical records and CT data was analyzed and compared between the two. The skull base parameters measured were choanal width, choanal height, mid-nasal skull base height and skull base slope. RESULTS: Of the 13 patients included, 3 had CHARGE syndrome and 10 had isolated BCA. Whilst the difference in mid-nasal height approached significance for the two groups, numbers were too small for a statistical difference to be identified. The mean value for choanal width in the isolated BCA group was significantly less the largest series of normative data available in the literature for comparison (p < 0.001). No skull base anomalies were noted in either group. CONCLUSION: While this is a small study with limited numbers, it is the first that has attempted to identify and measure the posterior nasal and skull base anatomy most pertinent to avoiding skull base injury in the surgical management of BCA.