Unified Endoscopic and Neurosurgical Approach for Frontoethmoidal Meningoencephalocele: A Case Study

Unified Endoscopic and Neurosurgical Approach for Frontoethmoidal Meningoencephalocele: A Case Study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Case Report Unified Endoscopic and Neurosurgical Approach for Frontoethmoidal Meningoencephalocele: A Case Study AHMAD HUSNI Sl, RAVINDERAN Shankarii, MARUTHAMUTHU Thevagi, LETCHUMANAN Pathma, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6147834/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Objective A congenital condition known as frontoethmoidal encephalomeningocele (FEEM) involves the herniation of the meninges and glial tissue, which can lead to abnormalities and morbidities in the neural system. The main management is surgical with aim is to remove the meningoencephalocele. We highlight the potential to improve patient outcomes and reduce morbidity. Method We present a FEEM case in our center at Hospital Raja Permaisuri Bainun(HRPB) whereby surgical approach were unified together with Otorhinolaryngology team and Neurosurgical team which result in successful removal of Encephalocele. Result A combined surgery with the Otorhinolaryngology and Neurosurgery team in which the encephalocele was then excised via a modified trans-basal bifrontal craniotomy and later proceeded with Hadad flap to cover defect. Conclusion The interdisciplinary collaboration between neurosurgeons and otorhinolaryngology surgeons is deemed essential in achieving both functional and aesthetic outcomes. This approach underlines the importance of tailored surgical strategies in managing FEEM. Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Introduction Meningoencephalocele (MECs) have been known since ancient times but were only described via a monograph written by Corvinus in 1749. Still, since it is a rare condition, data was difficult to register making the condition not very well known 1 . Frontoethmoidal meningoencephalocele (FEEM) is a congenital anomaly characterized by the herniation of brain tissue and meninges through a defect in the anterior skull base, particularly between the frontal and ethmoidal bones 2 . This condition manifests as a prenasal mass, which can be visibly prominent at birth. The pathology of FEEM is believed to arise from a disturbance in the separation of neural and surface ectoderm during embryonic development, leading to abnormal tissue connections and defects in the cranial structure 3 . Clinically, FEEM presents with a range of symptoms, including the presence of a visible mass on the forehead or nasal region, neurological deficits, and potential complications such as seizures and visual impairments. The anatomical location of FEEM typically involves the anterior cranial fossa, where the defect allows for the protrusion of neural tissue and meninges, creating a risk for associated infections and other complications. Surgical intervention is the primary treatment approach for FEEM, often involving a multidisciplinary team of neurosurgeons and craniofacial surgeons. The surgical strategy generally includes a two-stage procedure: the first stage focuses on repairing the neural defect through craniotomy, while the second stage addresses any craniofacial deformities. Recent advancements in surgical techniques, including endoscopic approaches, have improved outcomes and reduced patient recovery times. In Malaysia, the prevalence of FEEM is notably higher than in many Western countries, with estimates ranging from 1 in 5,000 to 1 in 6,000 live births. This increased prevalence highlights the need for targeted clinical management and research in the region to better understand the conditions and improve treatment outcomes. Case report We reported a case from our center whereby a 44-year-old Indian female patient with a body mass index (BMI) of 20 with an underlying history of hypertension and bronchial asthma presented to the otorhinolaryngology clinic with complaints of a 4-year history of left-sided clear nasal discharge associated with intermittent headache and blurring of vision for one month. She also complained of a sudden hearing loss over the left ear for one week. No previous surgical procedures or history of trauma before. Physical examination did not reveal any obvious facial deformities, however, nasal endoscopy evaluation showed a non-pulsatile, pinkish mass occupying the left nasal cavity and extending to the middle turbinate, without any demonstrable CSF leak. Magnetic resonance imaging (MRI) of the brain revealed patchy-meningeal enhancement at both frontal regions with left frontal leptomeningeal enhancement. An enhancing soft tissue density occupied the left nasal cavity and extended into the left ethmoid and frontal sinuses, with possible extension to the left maxillary sinus ( Fig. 1 , 2, 3 ) . The computed tomography (CT) scan of paranasal sinuses revealed bony erosions in the left ethmoid sinus, cribriform plate, frontal sinus, and maxillary sinus, along with a non-enhancing soft tissue density widening the left nasal cavity. The lesion extended to the left ethmoid and frontal sinuses and the left sphenoid sinus through a widened spheno-ethmoidal recess. Histopathology of the tissue confirmed the diagnosis of encephalocele as it revealed the presence of benign neuroglial tissue with acute inflammation. A final MRI then confirmed herniation of cerebral parenchyma into the left nasal cavity through the cribriform plate and ethmoid sinus. A combined surgery with the Otorhinolaryngology and Neurosurgery team in which the encephalocele was then excised via a modified trans-basal bifrontal craniotomy. Intra-operative finding was the presence of dense adhesions surrounding the encephalocele, and the brain at the site of the defect appeared gliotic. The encephalocele was excised intradurally, ensuring meticulous separation from the surrounding brain tissue. A 2x2cm bony defect which was seen at the cribriform plate, appeared to be communicating with the left frontal sinus and left ethmoid sinus. Endoscopically, the mass occupied the entire left nasal cavity with the skull base defect. The remnant of the encephalocele was removed transnasally and the defect was covered with a Hadad flap. Postoperatively, the patient was well with no new neurological deficits or worsening of previous symptoms. The patient was seen in the ORL clinic two weeks after discharge and no further complications such as cerebrospinal fluid (CSF) leak or meningitis. Figure 1 , 2, 3 are coronal, axial and sagittal images from T2 weighted MRI Brain.The herniation of cerebral parenchyma into the left nasal cavity can be seen in the coronal and sagittal sections with possible extension into the left maxillary sinus in the left axial section. Figure 4 shows endoscopic view of the mass in relation to the septum intranasally . Figure 5 and 6 show intranasal endoscopic pictures of the herniated sac after it has been amputated from the brain intradurally. Figure 7 shows removal of the mass endoscopically from the left nasal cavity. Discussion Frontoethmoidal encephalomeningocele (FEEM) is defined as a congenital bone abnormality in the anterior skull between the frontal and ethmoidal bones, with herniation of the meninges and brain tissues through the defect. FEEM has a distinct geographic distribution. Southeast Asia has a substantially higher prevalence (about 1 in 6000) than Western countries. 2 . It has been classified as a form of neural tube defect (NTD), with the primary degenerative alterations occurring internally at the foramen cecum and outwardly at the frontonaso-orbital region. The pathophysiology of FEEM appears to be predominantly caused by a disruption in the separation of neural and surface ectoderm at the point of final closure of the rostral neuropore during the final phase of neurulation. Insufficient apoptosis was proposed as a possible cause of separation failure, resulting in a midline mesodermal abnormality. Clinical and radiological features separate FEEM into four types: nasofrontal, nasoethmoidal, nasoorbital, and mixed. This classification is based on external bone deformities. It has been demonstrated that the incidence of NTD varies by region, environmental risk factors, genetic susceptibility, and recurrence risk. Although the variables that control proper closure and fusion at each site are unknown, they could comprise numerous genes or gene-environment interactions. Recent evidence supports the importance of 677CT mutation of 5,10 methylenetetrahydrofolate reductase (MTHFR) in NTD formation at some, but not all, of the closure sites. 4 . Study by Kanya et. al 2 indicated that low socioeconomic position, advanced maternal age, and a lengthy interpregnancy interval may lead to an unfavourable intrauterine environment that, with a certain genetic background such as Thai ethnicity, could contribute to the incidence of FEEM. This finding agrees with a previous observation from Sadewa AH.et al 5 that all FEEM patients in Malaysia were Malay among three major ethnic groups (Malay, Chinese, and Indian) in Malaysia. Micronutrients such as vitamins A, C, D, E, B6, and folic acid, the minerals zinc, copper, and selenium, and other dietary factors play an important role in metabolic processes and cellular and immune function, and deficiency of these nutrients proposed risk factors for FEEM 6 . FEEM is typically present at birth, rendering it uncommon for such cases to remain undetected for prolonged periods without any associated infection or complications. In some cases, encephaloceles are hidden and may present with symptoms such as snoring, nasal obstruction, CSF leak, or recurrent meningitis 7 In the adult population, they most commonly arise in the event of head trauma or iatrogenic trauma, making spontaneous cases a rare occurrence, comprising only 3–5% of all CSF leak cases 8 . A study by Nyquist GG et.al 9 involving 28 patients over 5 years found that idiopathic intracranial hypertension can increase the risk of spontaneous skull base encephaloceles. Typically, they present intranasally, with compressible masses near the nasal bridge often associated with hypertelorism however symptoms may also include CSF rhinorrhea, recurrent meningitis, and/or purulent nasal discharge 10 . As FEEM is uncommon in adults, diagnosing them is challenging due to their overlapping symptoms with more common sinonasal pathologies for example polyps, squamous cell carcinoma, and benign papillomas. These are differentiated from the encephaloceles by the absence of communication with the brain parenchyma. Thus, to diagnose them, a combination of both clinical examination and imaging is essential. Options for intranasal biopsy via endoscopic approach bring difficulty as it will lead to complications related to CSF leaking and meningitis 11 . Apart from that, imaging helps play a critical role in diagnosing FEEM, assessing its extent, and planning for surgical intervention. MRI imaging has been deemed as the imaging of choice for meningoencephalocele diagnosis although bony defects are best depicted on CT scans especially to look for both internal and external abnormalities. 3D CT reconstructions can enhance visualization of complex skull base anatomy and help identify the specific size and location of the defect through which the brain and meninges herniate. For MRI, it is essential to assess the content of encephalocele, including any herniated brain tissue or meninges, MRI provides superior soft tissue contrast to CT, making it vital for evaluating associated brain anomalies. It was also able to detect potential complications such as hydrocephalus or other neurological deficits related to the encephaloceles 12 . Children with increasing FEEM size, airway problems, impairment of binocular vision, and high risk of Central Nervous System infection warrant early surgical intervention. The prognosis and outcome depend on various factors such as the location of the encephaloceles, the size of the herniated sac, hydrocephalus, and other related infections. It is important to have a multidisciplinary approach to tackle the MEC issue and lessen the complications. Often, the involvement of a neurosurgical team with an otolaryngologist and maxillofacial teams are needed for better outcomes for both functional and cosmetic reasons. The main intention of surgical intervention is to isolate the brain parenchyma by excising the herniated non-functional part and fixing the defect in the skull base. Combining endoscopic nasal approach and craniotomy with conventional open surgery are two popular methods for FEEM management though the former is more advantageous to the latter because of the better visual of the skull base for surgery mapping. The endoscopic approach is considered the better approach due to the success rate and decreased post-operative complications for example CSF leak and meningitis 13 . Surgery usually consists of two steps whereby the first step is to remove the MEC and the second step involves skull base cranioplasty. Traditionally, there was two-stage process of disconnecting the encephalocele from the intracranial structure then followed by skull base correction later. However, recent advancements have led to one-stage surgeries, where both intracranial and extracranial components are addressed simultaneously. For skull base correction, there are various surgical techniques namely: one-layer, two-layer, underlay, overlay, or tobacco pouch 14 . Double layer technique with fascia for dura-plasty usually are used for anterior trans-ethmoidal meningoceles but other materials like septal mucoperichondrium, temporal muscles, turbinate bones, and others can be used while the second layer might be varied by using middle turbinate flap and nasoseptal flap 14 . As in our case, the Hadad-Bassagasteguy flap was used to cover the skull base defect, and synthetic glue was applied. Wihasto et al 15 conducted a meta-analysis of 28 studies including 1793 patients was conducted to determine the incidence of CSF leakage, its development to infection, the need for reoperation to repair the leakage, and the recurrence rate of extracranial and intracranial methods. The results showed that the prevalence of CSF leakage was 8% (95% CI, 0.04–0.12) in the intracranial method and 10% (95% CI, 0.01–0.23) in the extracranial technique. The subgroup analysis of the intracranial method revealed higher CSF leakage prevalence in the frontal craniotomy technique (9%; 95% CI, 0.03–0.16) than the subfrontal osteotomy (6%; 95% CI, 0.03–0.12).. The study also found that the extracranial method was associated with a considerably increased risk of CSF leakage (OR 2.82; 95% CI, 1.03–7.72), a higher reoperation rate (OR 5.38; 95% CI: 1.13–25.76), and a higher recurrence rate (RR 4.63; 95% CI, 1.51–14.20). The extracranial method had a greater rate of infected CSF leakage (OR 3.69; 95% CI, 0.52–26.37) than the intracranial route, but there was no statistical significance. This would imply that the extracranial method was associated with a higher risk of CSF leaking, more reoperations to address the CSF leakage, and higher recurrence rates. The infected CSF leaks between the extracranial and intracranial methods was not significantly different. When deciding for combine approach or solely endoscopic approach to tackle FEEM, few criterias need to overweight. First, the surgeon availability for both rhino-otolaryngologist and neurosurgeon at the same center. Next, the size of the lesion bring heavy impact in choosing the best method to excise it. Using endoscopic approach is well known to be minimally invasive, causing reduce tissue damage and overall morbidity 16 . Study also has reported that endoscopic approach shorten the hospital stay as compared to combined approach 17 . Visocchi et al. (2017) 18 also had discussed on the endoscopic approach(EEA) for addressing craniovertebral junction( CVJ) compared to previous goal standard using transoral approach. However, this study showed no significant changes in safety outcome for both technique and further extensive studies are needed as different size and locations of lesion decide the best way of approach. As in our case, the extensive size and location of the lesion prompt us to proceed with combined approach as opposed to endoscopic approach alone as endoscopic is more suitable for smaller lesion 19 . In addition, large defect of skull base required combined approach allowing more comprehensize repair thus reducing overall complications but with the expense of increase morbidity 20 . Fortunately, our patient recovered well without any complications. Conclusion A successful management strategy was presented for frontoethmoidal meningoencephalocele in an adult using a combined approach of endoscopic and extracranial techniques. This surgical method not only allowed for effective resection of the herniated brain parenchyma but also facilitated the reconstruction of the skull defect with the usage of a Hadad-Bassagasteguy flap to minimize the risk of complications mainly CSF leak. Further studies are warranted to evaluate long-term results and refine the surgical protocols in managing FEEM ensuring patients receiving highest standard of care. Declarations Funding : There was no funding involve in this case report. Consent to publish: The participant has consented to the submission of the case report to the journal. Consent to participate: The patient has consented to the submission of the case report for submission to the journal. Ethics declaration: Informed consent was obtained verbally before participation. Data availability: This case report does not involve any primary research data. All relevant clinical information has been included in the manuscript. No additional data are available. Competing interest declaration: The authors declare that they have no competing interests. Clinical Trial Number : Not applicable References Jimenez DF, Barone CM. Encephaloceles, meningoceles, and dermal sinuses. In: Albright AL, Adelson PD, Pollack IF, eds. Principles and Practice of Pediatric Neurosurgery. Thieme; 2008. p S182-S208 Suphapeetiporn K, Mahatumarat C, Rojvachiranonda N, Taecholarn C, Siriwan P, Srivuthana S, Shotelersuk V. Risk factors associated with the occurrence of frontoethmoidal encephalomeningocele. European Journal of Paediatric Neurology , 2008 Mar;12(2):102-7. Suwanwela C, Suwanwela N. A morphology classification of sincipital encephalomeningocele. J Neurosurg. 1972;36:201-211. Wenstrom KD, Johanning GL, Owen J, et al. Amniotic fluid homocysteine levels, 5,10-methylenetetrahydrofolate reductase genotypes, and neural tube closure sites. Am J Med Genet. 2000;90:6-11. Sadewa AH, Sutomo R, Istiadjid M, et al. C677T mutation in the MTHFR gene was not found in patients with frontoethmoidal encephalocele in East Java, Indonesia. Pediatr Int. 2004;46:409-414. Oley MC, Oley MH, Flapper W, Kepel REM, Faruk M. Evaluation of long-term results following surgical correction of frontoethmoidal encephalomeningocele. 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J., Matula, C., & Arnoldner, C. (2022). Combined Open Surgical and Endoscopic Approach for Management of a Meningoencephalocele After Iatrogenic Perforation of the Anterior Skull Base in a Young Infant. Cureus . https://doi.org/10.7759/cureus.24797 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6147834","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":441573266,"identity":"a05baa2c-3b3b-4bb7-91b3-9e248b6fd68b","order_by":0,"name":"AHMAD HUSNI 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version\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-6147834/v1/37c0f564e5edfa6993ffd034.png"},{"id":83279008,"identity":"b1b9044e-9abc-4f91-8ef2-4452fa9eca17","added_by":"auto","created_at":"2025-05-22 09:53:51","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2074891,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6147834/v1/b689769b-7d54-485b-86aa-f01278a22d42.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Unified Endoscopic and Neurosurgical Approach for Frontoethmoidal Meningoencephalocele: A Case Study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eMeningoencephalocele (MECs) have been known since ancient times but were only described via a monograph written by Corvinus in 1749. Still, since it is a rare condition, data was difficult to register making the condition not very well known\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e. Frontoethmoidal meningoencephalocele (FEEM) is a congenital anomaly characterized by the herniation of brain tissue and meninges through a defect in the anterior skull base, particularly between the frontal and ethmoidal bones\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e. This condition manifests as a prenasal mass, which can be visibly prominent at birth. The pathology of FEEM is believed to arise from a disturbance in the separation of neural and surface ectoderm during embryonic development, leading to abnormal tissue connections and defects in the cranial structure\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. Clinically, FEEM presents with a range of symptoms, including the presence of a visible mass on the forehead or nasal region, neurological deficits, and potential complications such as seizures and visual impairments. The anatomical location of FEEM typically involves the anterior cranial fossa, where the defect allows for the protrusion of neural tissue and meninges, creating a risk for associated infections and other complications. Surgical intervention is the primary treatment approach for FEEM, often involving a multidisciplinary team of neurosurgeons and craniofacial surgeons. The surgical strategy generally includes a two-stage procedure: the first stage focuses on repairing the neural defect through craniotomy, while the second stage addresses any craniofacial deformities. Recent advancements in surgical techniques, including endoscopic approaches, have improved outcomes and reduced patient recovery times. In Malaysia, the prevalence of FEEM is notably higher than in many Western countries, with estimates ranging from 1 in 5,000 to 1 in 6,000 live births. This increased prevalence highlights the need for targeted clinical management and research in the region to better understand the conditions and improve treatment outcomes.\u003c/p\u003e"},{"header":"Case report","content":"\u003cp\u003eWe reported a case from our center whereby a 44-year-old Indian female patient with a body mass index (BMI) of 20 with an underlying history of hypertension and bronchial asthma presented to the otorhinolaryngology clinic with complaints of a 4-year history of left-sided clear nasal discharge associated with intermittent headache and blurring of vision for one month. She also complained of a sudden hearing loss over the left ear for one week. No previous surgical procedures or history of trauma before. Physical examination did not reveal any obvious facial deformities, however, nasal endoscopy evaluation showed a non-pulsatile, pinkish mass occupying the left nasal cavity and extending to the middle turbinate, without any demonstrable CSF leak. Magnetic resonance imaging (MRI) of the brain revealed patchy-meningeal enhancement at both frontal regions with left frontal leptomeningeal enhancement. An enhancing soft tissue density occupied the left nasal cavity and extended into the left ethmoid and frontal sinuses, with possible extension to the left maxillary sinus \u003cb\u003e(\u003c/b\u003e Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, 2, \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e. The computed tomography (CT) scan of paranasal sinuses revealed bony erosions in the left ethmoid sinus, cribriform plate, frontal sinus, and maxillary sinus, along with a non-enhancing soft tissue density widening the left nasal cavity. The lesion extended to the left ethmoid and frontal sinuses and the left sphenoid sinus through a widened spheno-ethmoidal recess. Histopathology of the tissue confirmed the diagnosis of encephalocele as it revealed the presence of benign neuroglial tissue with acute inflammation. A final MRI then confirmed herniation of cerebral parenchyma into the left nasal cavity through the cribriform plate and ethmoid sinus. A combined surgery with the Otorhinolaryngology and Neurosurgery team in which the encephalocele was then excised via a modified trans-basal bifrontal craniotomy. Intra-operative finding was the presence of dense adhesions surrounding the encephalocele, and the brain at the site of the defect appeared gliotic. The encephalocele was excised intradurally, ensuring meticulous separation from the surrounding brain tissue. A 2x2cm bony defect which was seen at the cribriform plate, appeared to be communicating with the left frontal sinus and left ethmoid sinus. Endoscopically, the mass occupied the entire left nasal cavity with the skull base defect. The remnant of the encephalocele was removed transnasally and the defect was covered with a Hadad flap. Postoperatively, the patient was well with no new neurological deficits or worsening of previous symptoms. The patient was seen in the ORL clinic two weeks after discharge and no further complications such as cerebrospinal fluid (CSF) leak or meningitis.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, 2, \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003e are coronal, axial and sagittal images from T2 weighted MRI Brain.The herniation of cerebral parenchyma into the left nasal cavity can be seen in the coronal and sagittal sections with possible extension into the left maxillary sinus in the left axial section.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure 4 shows endoscopic view of the mass in relation to the septum intranasally .\u003c/p\u003e \u003cp\u003eFigure 5 and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e6\u003c/span\u003e show intranasal endoscopic pictures of the herniated sac after it has been amputated from the brain intradurally.\u003c/p\u003e \u003cp\u003eFigure 7 shows removal of the mass endoscopically from the left nasal cavity.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eFrontoethmoidal encephalomeningocele (FEEM) is defined as a congenital bone abnormality in the anterior skull between the frontal and ethmoidal bones, with herniation of the meninges and brain tissues through the defect. FEEM has a distinct geographic distribution. Southeast Asia has a substantially higher prevalence (about 1 in 6000) than Western countries.\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e. It has been classified as a form of neural tube defect (NTD), with the primary degenerative alterations occurring internally at the foramen cecum and outwardly at the frontonaso-orbital region. The pathophysiology of FEEM appears to be predominantly caused by a disruption in the separation of neural and surface ectoderm at the point of final closure of the rostral neuropore during the final phase of neurulation. Insufficient apoptosis was proposed as a possible cause of separation failure, resulting in a midline mesodermal abnormality. Clinical and radiological features separate FEEM into four types: nasofrontal, nasoethmoidal, nasoorbital, and mixed. This classification is based on external bone deformities. It has been demonstrated that the incidence of NTD varies by region, environmental risk factors, genetic susceptibility, and recurrence risk. Although the variables that control proper closure and fusion at each site are unknown, they could comprise numerous genes or gene-environment interactions. Recent evidence supports the importance of 677CT mutation of 5,10 methylenetetrahydrofolate reductase (MTHFR) in NTD formation at some, but not all, of the closure sites.\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e. Study by Kanya et. al\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e indicated that low socioeconomic position, advanced maternal age, and a lengthy interpregnancy interval may lead to an unfavourable intrauterine environment that, with a certain genetic background such as Thai ethnicity, could contribute to the incidence of FEEM. This finding agrees with a previous observation from Sadewa AH.et al\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e that all FEEM patients in Malaysia were Malay among three major ethnic groups (Malay, Chinese, and Indian) in Malaysia. Micronutrients such as vitamins A, C, D, E, B6, and folic acid, the minerals zinc, copper, and selenium, and other dietary factors play an important role in metabolic processes and cellular and immune function, and deficiency of these nutrients proposed risk factors for FEEM\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eFEEM is typically present at birth, rendering it uncommon for such cases to remain undetected for prolonged periods without any associated infection or complications. In some cases, encephaloceles are hidden and may present with symptoms such as snoring, nasal obstruction, CSF leak, or recurrent meningitis\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e In the adult population, they most commonly arise in the event of head trauma or iatrogenic trauma, making spontaneous cases a rare occurrence, comprising only 3\u0026ndash;5% of all CSF leak cases\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e. A study by Nyquist GG et.al\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e involving 28 patients over 5 years found that idiopathic intracranial hypertension can increase the risk of spontaneous skull base encephaloceles. Typically, they present intranasally, with compressible masses near the nasal bridge often associated with hypertelorism however symptoms may also include CSF rhinorrhea, recurrent meningitis, and/or purulent nasal discharge\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e. As FEEM is uncommon in adults, diagnosing them is challenging due to their overlapping symptoms with more common sinonasal pathologies for example polyps, squamous cell carcinoma, and benign papillomas. These are differentiated from the encephaloceles by the absence of communication with the brain parenchyma. Thus, to diagnose them, a combination of both clinical examination and imaging is essential. Options for intranasal biopsy via endoscopic approach bring difficulty as it will lead to complications related to CSF leaking and meningitis\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e. Apart from that, imaging helps play a critical role in diagnosing FEEM, assessing its extent, and planning for surgical intervention. MRI imaging has been deemed as the imaging of choice for meningoencephalocele diagnosis although bony defects are best depicted on CT scans especially to look for both internal and external abnormalities. 3D CT reconstructions can enhance visualization of complex skull base anatomy and help identify the specific size and location of the defect through which the brain and meninges herniate. For MRI, it is essential to assess the content of encephalocele, including any herniated brain tissue or meninges, MRI provides superior soft tissue contrast to CT, making it vital for evaluating associated brain anomalies. It was also able to detect potential complications such as hydrocephalus or other neurological deficits related to the encephaloceles\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eChildren with increasing FEEM size, airway problems, impairment of binocular vision, and high risk of Central Nervous System infection warrant early surgical intervention. The prognosis and outcome depend on various factors such as the location of the encephaloceles, the size of the herniated sac, hydrocephalus, and other related infections. It is important to have a multidisciplinary approach to tackle the MEC issue and lessen the complications. Often, the involvement of a neurosurgical team with an otolaryngologist and maxillofacial teams are needed for better outcomes for both functional and cosmetic reasons. The main intention of surgical intervention is to isolate the brain parenchyma by excising the herniated non-functional part and fixing the defect in the skull base. Combining endoscopic nasal approach and craniotomy with conventional open surgery are two popular methods for FEEM management though the former is more advantageous to the latter because of the better visual of the skull base for surgery mapping. The endoscopic approach is considered the better approach due to the success rate and decreased post-operative complications for example CSF leak and meningitis\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e. Surgery usually consists of two steps whereby the first step is to remove the MEC and the second step involves skull base cranioplasty. Traditionally, there was two-stage process of disconnecting the encephalocele from the intracranial structure then followed by skull base correction later. However, recent advancements have led to one-stage surgeries, where both intracranial and extracranial components are addressed simultaneously. For skull base correction, there are various surgical techniques namely: one-layer, two-layer, underlay, overlay, or tobacco pouch\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e. Double layer technique with fascia for dura-plasty usually are used for anterior trans-ethmoidal meningoceles but other materials like septal mucoperichondrium, temporal muscles, turbinate bones, and others can be used while the second layer might be varied by using middle turbinate flap and nasoseptal flap\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e. As in our case, the Hadad-Bassagasteguy flap was used to cover the skull base defect, and synthetic glue was applied. Wihasto et al\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e conducted a meta-analysis of 28 studies including 1793 patients was conducted to determine the incidence of CSF leakage, its development to infection, the need for reoperation to repair the leakage, and the recurrence rate of extracranial and intracranial methods. The results showed that the prevalence of CSF leakage was 8% (95% CI, 0.04\u0026ndash;0.12) in the intracranial method and 10% (95% CI, 0.01\u0026ndash;0.23) in the extracranial technique. The subgroup analysis of the intracranial method revealed higher CSF leakage prevalence in the frontal craniotomy technique (9%; 95% CI, 0.03\u0026ndash;0.16) than the subfrontal osteotomy (6%; 95% CI, 0.03\u0026ndash;0.12).. The study also found that the extracranial method was associated with a considerably increased risk of CSF leakage (OR 2.82; 95% CI, 1.03\u0026ndash;7.72), a higher reoperation rate (OR 5.38; 95% CI: 1.13\u0026ndash;25.76), and a higher recurrence rate (RR 4.63; 95% CI, 1.51\u0026ndash;14.20). The extracranial method had a greater rate of infected CSF leakage (OR 3.69; 95% CI, 0.52\u0026ndash;26.37) than the intracranial route, but there was no statistical significance. This would imply that the extracranial method was associated with a higher risk of CSF leaking, more reoperations to address the CSF leakage, and higher recurrence rates. The infected CSF leaks between the extracranial and intracranial methods was not significantly different.\u003c/p\u003e \u003cp\u003eWhen deciding for combine approach or solely endoscopic approach to tackle FEEM, few criterias need to overweight. First, the surgeon availability for both rhino-otolaryngologist and neurosurgeon at the same center. Next, the size of the lesion bring heavy impact in choosing the best method to excise it. Using endoscopic approach is well known to be minimally invasive, causing reduce tissue damage and overall morbidity\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e. Study also has reported that endoscopic approach shorten the hospital stay as compared to combined approach\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e. Visocchi et al. (2017)\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e also had discussed on the endoscopic approach(EEA) for addressing craniovertebral junction( CVJ) compared to previous goal standard using transoral approach. However, this study showed no significant changes in safety outcome for both technique and further extensive studies are needed as different size and locations of lesion decide the best way of approach.\u003c/p\u003e \u003cp\u003eAs in our case, the extensive size and location of the lesion prompt us to proceed with combined approach as opposed to endoscopic approach alone as endoscopic is more suitable for smaller lesion\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e. In addition, large defect of skull base required combined approach allowing more comprehensize repair thus reducing overall complications but with the expense of increase morbidity\u003csup\u003e\u003cb\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/b\u003e\u003c/sup\u003e. Fortunately, our patient recovered well without any complications.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eA successful management strategy was presented for frontoethmoidal meningoencephalocele in an adult using a combined approach of endoscopic and extracranial techniques. This surgical method not only allowed for effective resection of the herniated brain parenchyma but also facilitated the reconstruction of the skull defect with the usage of a Hadad-Bassagasteguy flap to minimize the risk of complications mainly CSF leak.\u003c/p\u003e \u003cp\u003eFurther studies are warranted to evaluate long-term results and refine the surgical protocols in managing FEEM ensuring patients receiving highest standard of care.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e:\u003c/p\u003e\n\u003cp\u003eThere was no funding involve in this case report.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to publish:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe participant has consented to the submission of the case report to the journal.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to participate:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe patient has consented to the submission of the case report for submission to the journal.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics declaration:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eInformed consent was obtained verbally before participation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis case report does not involve any primary research data. All relevant clinical information has been included in the manuscript. No additional data are available.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interest declaration:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical Trial Number\u003c/strong\u003e:\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eJimenez DF, Barone CM. Encephaloceles, meningoceles, and dermal sinuses. In: Albright AL, Adelson PD, Pollack IF, eds. Principles and Practice of Pediatric Neurosurgery. Thieme; 2008. p S182-S208\u003c/li\u003e\n\u003cli\u003eSuphapeetiporn K, Mahatumarat C, Rojvachiranonda N, Taecholarn C, Siriwan P, Srivuthana S, Shotelersuk V. Risk factors associated with the occurrence of frontoethmoidal encephalomeningocele. \u003cem\u003eEuropean Journal of Paediatric Neurology\u003c/em\u003e, 2008 Mar;12(2):102-7.\u003c/li\u003e\n\u003cli\u003eSuwanwela C, Suwanwela N. A morphology classification of sincipital encephalomeningocele. \u003cem\u003eJ Neurosurg.\u003c/em\u003e 1972;36:201-211.\u003c/li\u003e\n\u003cli\u003eWenstrom KD, Johanning GL, Owen J, et al. Amniotic fluid homocysteine levels, 5,10-methylenetetrahydrofolate reductase genotypes, and neural tube closure sites. \u003cem\u003eAm J Med Genet.\u003c/em\u003e 2000;90:6-11.\u003c/li\u003e\n\u003cli\u003eSadewa AH, Sutomo R, Istiadjid M, et al. C677T mutation in the MTHFR gene was not found in patients with frontoethmoidal encephalocele in East Java, Indonesia. \u003cem\u003ePediatr Int.\u003c/em\u003e 2004;46:409-414.\u003c/li\u003e\n\u003cli\u003eOley MC, Oley MH, Flapper W, Kepel REM, Faruk M. 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Endonasal endoscopic repair of cerebrospinal fluid leaks versus craniotomy: comparison of the outcomes. \u003cem\u003eHippokratia\u003c/em\u003e, \u003cem\u003e20\u003c/em\u003e(4), 299. https://pmc.ncbi.nlm.nih.gov/articles/PMC5788229/\u003c/li\u003e\n\u003cli\u003eVisocchi M, Signorelli F, Liao C, Rigante M, Paludetti G, Barbagallo G, Olivi A, Endoscopic Endonasal Approach for Craniovertebral Junction Pathologies: Myth and Truth in Clinical Series and Personal Experience, World Neurosurgery (2017), doi: 10.1016/j.wneu.2017.01.099.\u003c/li\u003e\n\u003cli\u003e\u0026zwnj;Saud Arafat, A., AlMalki, R., Saud Arafat, A., Asiri, M., Almutairi, A., \u0026amp; Al Mahdi, M. J. (2022). Endoscopic Repair of Bilateral Frontal Meningoencephalocele: A Case Report. \u003cem\u003eSurgical Case Reports\u003c/em\u003e, 1\u0026ndash;4. https://doi.org/10.31487/j.scr.2022.08.05\u003c/li\u003e\n\u003cli\u003eMercea, P. A., Gadenstaetter, A. J., Matula, C., \u0026amp; Arnoldner, C. (2022). Combined Open Surgical and Endoscopic Approach for Management of a Meningoencephalocele After Iatrogenic Perforation of the Anterior Skull Base in a Young Infant. \u003cem\u003eCureus\u003c/em\u003e. https://doi.org/10.7759/cureus.24797\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-6147834/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6147834/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjective\u003c/h2\u003e \u003cp\u003eA congenital condition known as frontoethmoidal encephalomeningocele (FEEM) involves the herniation of the meninges and glial tissue, which can lead to abnormalities and morbidities in the neural system. The main management is surgical with aim is to remove the meningoencephalocele. We highlight the potential to improve patient outcomes and reduce morbidity.\u003c/p\u003e\u003ch2\u003eMethod\u003c/h2\u003e \u003cp\u003eWe present a FEEM case in our center at Hospital Raja Permaisuri Bainun(HRPB) whereby surgical approach were unified together with Otorhinolaryngology team and Neurosurgical team which result in successful removal of Encephalocele.\u003c/p\u003e\u003ch2\u003eResult\u003c/h2\u003e \u003cp\u003eA combined surgery with the Otorhinolaryngology and Neurosurgery team in which the encephalocele was then excised via a modified trans-basal bifrontal craniotomy and later proceeded with Hadad flap to cover defect.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThe interdisciplinary collaboration between neurosurgeons and otorhinolaryngology surgeons is deemed essential in achieving both functional and aesthetic outcomes. This approach underlines the importance of tailored surgical strategies in managing FEEM.\u003c/p\u003e","manuscriptTitle":"Unified Endoscopic and Neurosurgical Approach for Frontoethmoidal Meningoencephalocele: A Case Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-04-21 10:38:06","doi":"10.21203/rs.3.rs-6147834/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"322146f5-ddf1-4a2d-bf92-8c624b9b27ce","owner":[],"postedDate":"April 21st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-06-14T04:53:13+00:00","versionOfRecord":[],"versionCreatedAt":"2025-04-21 10:38:06","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6147834","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6147834","identity":"rs-6147834","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}