Clinical Imaging 35 (2011) 309 – 311
Case reports
Intranasal meningoencephalocele presenting as a nasal polyp — a case report Shraddha S. Mukerji a , Hemant A. Parmar b,⁎, Sachin Gujar b , Peter Passamani c a
Department of Pediatric Otolaryngology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA b Department of Radiology, University of Michigan, Ann Arbor, MI, USA c Department of Otolaryngology-Head and Neck Surgery, University of Michigan, Ann Arbor, MI, USA Received 10 August 2009; accepted 20 September 2009
Abstract We present a case of an intranasal meningoencephalocele masquerading as an ‘intranasal polyp’ in a 17-month-old child. Nasal meningoencephaloceles are uncommon anomalies and require a high index of suspicion for their diagnosis. Biopsy of such lesions without prior imaging studies can be detrimental because of the risk of cerebrospinal fluid leak and meningitis, and is therefore contraindicated. This case reiterates the fact that any child with an intranasal mass should undergo appropriate imaging studies prior to excisional biopsy. © 2011 Elsevier Inc. All rights reserved. Keywords: Meningoencephalocele; Biopsy; Congenital; Intranasal
1. Case report A 17-month-old, otherwise healthy male was referred for evaluation of chronic nasal discharge and recurrent ear infections. The mother was concerned that the child had thick, sometimes purulent, nonbloody, non-foul-smelling nasal discharge since birth. There was history of snoring and loud nocturnal mouth breathing. There was no history of feeding difficulty, headache, neck pain or vision abnormalities. There was no history of otorrhea, hearing loss or speech delay. Physical examination revealed bilateral otitis media with effusions (confirmed with tympanograms). Anterior rhinoscopic examination showed edematous left inferior turbinate with congestion of the right nasal cavity. There were no focal neurological signs or craniofacial dysmorphism. The child was prescribed nasal steroid sprays and decongestants and asked to return for follow-up in 4 weeks.
⁎ Corresponding author. Department of Radiology, University of Michigan, Taubman Center/B1/132 F, 1500 East Medical Center, Ann Arbor, MI 48109-0302. Tel.: +1 734 936 7291; fax: +1 734 936 0013. E-mail addresses:
[email protected],
[email protected] (H.A. Parmar). 0899-7071/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.clinimag.2011.01.005
The child returned 4 weeks later with resolution of his ear symptoms. However, there was no significant improvement of nasal symptoms. Otoscopic exam was normal. Anterior rhinoscopic examination now showed a pale, purplish white swelling in the left nasal cavity at the anterior head of the inferior turbinate. There was associated deviation of the nasal septum to the right. There was also mild widening of the nasal bridge. Coronal computed tomography (CT) scan of the head and the maxillofacial area demonstrated a large, low-attenuation lesion occupying almost the entire left nasal cavity (Fig. 1A). It was associated with bony remodeling and right-sided deviation of the bony nasal septum. Examination of the bony windows on the CT scan revealed a defect in the left cribriform plate (arrows, Fig. 1B). Magnetic resonance imaging (MRI) scan demonstrated the mass to be cystic in nature, with low signal on T1- and high signal on T2-weighted images (WIs) (arrowheads, Fig. 2). There was a clear connection between this lesion and the intracranial cerebrospinal fluid (CSF) space (arrows, Fig. 2). There was no definite brain parenchymal tissue seen within this cystic lesion, and the underlying inferior frontal lobe showed no abnormality. The child underwent successful excision of the nasal lesion and has been symptom-free to date.
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Fig. 1. (A) Coronal CT scan of the maxillofacial region demonstrates a large, low-attenuation lesion within the left nasal cavity (arrowheads). It is associated with mild right-sided deviation of the bony nasal septum. (B) Examination of the bony windows reveals a defect in the left cribriform plate (arrows).
2. Discussion Nasal meningoencephaloceles are uncommon, congenital midline nasal masses, occurring in one in 4000 live births [1–3]. During the sixth or the seventh gestational week, two transient spaces are recognized in the developing frontonasal area: [1] fonticulus frontalis, which is located in the midline between the paired frontal and nasal bones, and [2] prenasal space, which is located between the nasal bones and the nasal capsule. During development, frontal dural projections extend from the foramen cecum (anterior to the crista
galli), [4] traverse these spaces and temporarily end in the subcutaneous soft tissue of the midnasal bridge. Persistence of these dural projections and of abnormal separation of neuroectodermal tissues gives rise to midline nasal masses including meningoceles. The most accepted theory for their development is protrusion of the forebrain secondary to abnormal closure of the anterior neuropore [3]. This condition occurs equally in males and females [3]. Majority of meningoencephaloceles are diagnosed at birth or in early infancy. Intranasal meningoencephaloceles appear as pale or purplish white masses within the nasal cavity [1]. Owing to their intracranial connection, there is expansion of the mass with crying, straining or compression of the ipsilateral jugular vein (Furstenberg test). Depending on their location, they can also cause cosmetic nasal deformity, vision abnormalities, persistent rhinorrhea, nasal obstruction and anosmia. Complications such as CSF rhinorrhea, meningitis and epistaxis can occur [2]. Meningoencephaloceles can be classified on the basis of their location or tissue content. Depending on their location, these lesions are classified as occipital (75%) or frontal (25%) [3]. Frontal meningoencephaloceles are further subdivided as sincipital (60%) and basal (40%). Sincipital meningoencephaloceles occur as extranasal masses (nasofrontal, nasoethmoid or naso-orbital), while basal meningoencephaloceles appear intranasally and depending upon their site of herniation can be divided as transethmoidal, sphenoethmoidal, transsphenoidal and sphenomaxillary. Meningoencephaloceles can contain meninges only (meningocele) (as seen in our case); or meninges and neural tissue (meningoencephalocele or encephalocele); and/or meninges, neural tissue and ventricular system (meningoencephalocystoceles) [1,3]. The clinical differential diagnosis includes various congenital or acquired midline nasal masses [4]. Nasal dermoids are the most common nasal anomalies. They appear as midline nasal masses, with or without a sinus tract. The external opening of the sinus tract is usually surrounded by a tuft of hair. Nasal gliomas can be extranasal or intranasal, may or may not occur in the midline, are usually firm, are noncompressible, do not transilluminate and do not increase with Valsalva testing. Hemangiomas are the commonest benign vascular tumors of infancy. Unilateral nasal polyps are distinctly uncommon in the pediatric population. If bilateral nasal polyps are seen, a sweat chloride test should be done to rule out cystic fibrosis [5]. Neuroimaging is crucial in the determination of a connection between the meningoencephalocele and the anterior cranial fossae as well as to differentiate the lesion from other midline nasal masses. Cross-sectional studies help assess the location, size and extent of the mass which guides surgical management. Thin-section, high-resolution, axial and coronal CT images help delineate bony anatomy, especially to evaluate the integrity of the anterior skull base [3]. Pitfalls particularly common to CT imaging interpretation include unossified frontal, nasal and ethmoid bones in
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Fig. 2. MRI scan demonstrates the mass to be cystic in nature, with low signal on T1- and high signal on T2-WIs (arrows). There is a clear connection between this lesion and the intracranial CSF space (arrowheads). There was no definite brain parenchymal tissue seen within this cystic lesion, and the underlying inferior frontal lobe showed no abnormality.
the first year of life that are misinterpreted as skull base defects, morphology and size of the foramen cecum, and the natural congestion of the anterior nasal septum [6]. Magnetic resonance imaging serves as a complementary tool to CT for soft tissue characterization of nasal masses and evaluation of their intracranial connections. Meningoceles demonstrate hypointensity on T1 WI and hyperintensity on T2 WI, signal characteristics of CSF [6]. The brain parenchymal component in meningoencephalocele demonstrates isointensity with respect to the adjacent cerebral cortex; sometimes it can demonstrate high T2 signal if there is associated cortical dysplasia. Contrast-enhanced images should be obtained to aid differential diagnosis or when infection is suspected [3]. The preferred management of a meningoencephalocele is surgical excision. The optimal age of repair of a congenital meningoencephalocele is not known [7]. The choice of surgical approach is dictated by location, size and extent of the lesion. Congenital meningoencephaloceles are tradition-
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ally excised via a bicoronal approach with a frontal craniotomy and intracranial repair of dural defect [3,7]. Complications of this approach include scarring, anosmia, intracranial hemorrhage and frontal lobe dysfunction. With advances in endoscopic techniques, it is now feasible to excise meningoencephaloceles endoscopically [1,7]. The key to a successful closure of the intracranial defect via this approach includes precise delineation and bipolar excision of the neck of the meningoencephalocele sac, removal of the sinonasal mucosa around the defect and precise placement of graft material [1,7]. Advantages of this approach include avoidance of facial scar, reduced morbidity and reduced hospital stay. Furthermore, there is no detrimental effect on facial growth [8]. In conclusion, congenital intranasal meningoencephalocele should be considered in the differential diagnosis of any unilateral nasal mass in the pediatric population. Though uncommon, these lesions can lead to potentially serious complications such as CSF leak and recurrent meningitis. Both CT and MRI are required for accurate delineation and correct diagnosis. A multidisciplinary approach involving neurosurgeons and otolaryngologists is of paramount importance for a successful outcome. References [1] Woodworth BA, Schlosser RJ, Faust RA, Bolger WE. Evolutions in the management of congenital intranasal skull base defects. Arch Otolaryngol Head Neck Surg 2004;130:1283–8. [2] Kennard CD, Rasmussen JE. Congenital midline nasal masses: diagnosis and management. J Dermatol Surg Oncol 1990;16:1025–36. [3] Rahbar R, Resto VA, Robson CD, Perez-Atyade AR, Goumnerova LC, McGill TJ, Healy GB. Nasal glioma and encephalocele: diagnosis and management. Laryngoscope 2003;113:2069–77. [4] Dasgupta NR, Bentz ML. Nasal gliomas: identification and differentiation from hemangiomas. J Craniofac Surg 2003;14:736–8. [5] Bown OE. Current management of pediatric nasal airway obstruction. Curr Opin Otolaryngol Head Neck Surg 1995;3:402–7. [6] Hedlund G. Congenital frontonasal masses: developmental anatomy, malformations, and MR imaging. Pediatr Radiol 2006;36:647–662; [quiz 726–727]. [7] Woodworth B, Schlosser RJ. Endoscopic repair of a congenital intranasal encephalocele in a 23 months old infant. Int J Pediatr Otorhinolaryngol 2005;69:1007–9. [8] Bothwell MR, Piccirillo JF, Lusk RP, Ridenour BD. Long-term outcome of facial growth after functional endoscopic sinus surgery. Otolaryngol Head Neck Surg 2002;126:628–34.
