Ebook Diagnostic imaging head and neck (2nd edition): Part 2
Diagnostic Imaging Head and Neck
Part IV - Sinonasal Cavities and Orbit Section 1 - Nose and Sinus Introduction and Overview Sinonasal Overview > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section 1 - Nose and Sinus > Introduction and Overview > Sinonasal Overview Sinonasal Overview Michelle A. Michel, MD Summary Thoughts: Sinus and Nose The anatomy of the sinonasal (SN) cavities is as unique as a person's fingerprints. The nasal cavity (NC) is centrally located and is surrounded by the paranasal sinuses (PS). Because the SN region is comprised of air-filled spaces and complex bony architecture, CT is often the first-line imaging modality. CT is used for determining the extent of disease and is also helpful for surgical planning and intraoperative guidance. As in all regions of the H&N, information, such as patient demographics, presenting symptoms, and clinical exam findings, are critical for interpreting imaging studies of this area. It is important to understand the drainage pathways of the PS as one can then predict patterns of disease based upon the point of an obstructing lesion. Inflammatory disease is by far the most common pathology. However, isolated inflammatory disease of the sphenoid sinus is unusual and should raise suspicion for other pathologies including neoplasm or cephaloceles, particularly if there is an associated bone defect. Fortunately, malignancies of the SN
cavities are rare. They tend to present at an advanced stage and are often in close proximity to vital structures (orbit, cranial nerves, and skull base). These tumors are difficult to completely resect and are associated with high surgical morbidity. Presurgical tumor mapping in such cases is best accomplished with multiplanar MR. Imaging Approaches and Indications CT is the modality of choice for evaluation of inflammatory disease. CT is more sensitive for detecting Ca++ in lesions (fibro-osseous lesions, inverted papilloma, esthesioneuroblastoma) and for evaluating changes in adjacent bone. Coronal images best demonstrate the anatomy of the ostiomeatal unit (OMU). MR can be used as a complement to CT for evaluating complicated inflammatory or neoplastic disease. MR is generally indicated for evaluation of complex inflammatory disease and neoplasms. It is optimal for assessing extension beyond the SN cavities, evaluating perineural tumor spread, and differentiating tumor from postobstructed secretions. Imaging Protocols Traditionally, ≤ 3 mm direct coronal images are obtained prone and angled perpendicular to the palate. With multidetector CT, coronal reformatted images can be generated from a thin slice axial data set acquired in the supine position. This is advantageous as images are less degraded by motion artifact and dental amalgam can be avoided. Axial images can often be used in image-guidance systems, obviating additional radiation for “treatment planning” CT prior to surgery. Sagittal reformatted images are helpful for delineating frontal recess (FR) and the sphenoethmoid region anatomy. MR imaging protocols generally include axial and coronal T1, STIR, and T1WI C+ images with fat suppression. Angiography is rarely needed for diagnostic purposes but may be performed for intervention prior to resection of vascular neoplasms. Imaging Anatomy The sinonasal region is comprised of the NC and the surrounding PS. There are important anatomic relationships with surrounding compartments of the extracranial head and neck, including the anterior cranial fossa, orbits, pterygopalatine and infratemporal fossae, and oral cavity. The SN cavities extend into the maxillary, frontal, sphenoid, and ethmoid bones. Superiorly, the frontal sinuses border the anterior margin of the anterior cranial fossa. The cribriform plate (CP) and fovea ethmoidalis form the borders between the superior NC and ethmoid, respectively. The hard palate separates the NC from the oral cavity. The NC communicates posteriorly with the nasopharynx via the choanae. The orbits are separated from the ethmoid sinuses by the thin lamina papyracea and are separated from the maxillary sinuses by the orbital floors. Posterior to the maxillary sinuses are the pterygopalatine fossae, which communicate superiorly with the orbital apices & laterally with masticator space. The NC is centrally located and is divided in the midline by the nasal septum. The bony septum is formed from the perpendicular plate of the ethmoid posterosuperiorly and vomer bone posteroinferiorly. Anteriorly the septum is comprised of cartilage. Paired superior, middle, and inferior turbinates project into the NC and their corresponding 841
Diagnostic Imaging Head and Neck meati exit inferior to each. The middle turbinate has two attachments: 1) superiorly to the CP via the vertical lamella,
and 2) posterolaterally to the lamina papyracea via the basal (ground) lamella. The frontal sinuses are often asymmetric in size and are divided in the midline by an intersinus septum. Inferomedially, the frontal sinus narrows toward its ostium, which drains into its FR. The FR is formed by the walls of surrounding structures. The drainage of the FR is determined by the insertion of the uncinate process. Most often the uncinate inserts laterally onto the lamina papyracea and secretions drain into the middle meatus (MM). Less frequently, the uncinate inserts onto the anterior skull base or middle turbinate; FR secretions drain via the infundibulum into the MM. Paired groups of 13-18 air cells form the ethmoid labyrinths. These cells are divided into anterior and posterior groups by the basal lamella. The anterior air cells drain into the anterior recess of the hiatus semilunaris and middle meatus via the ethmoid bulla. The posterior air cells drain into the superior meatus and sphenoethmoidal recess (SER). The maxillary sinuses lie lateral to the NC and inferior to the orbits. Each drains via its maxillary ostium into the infundibulum, then via the hiatus semilunaris into the MM. The maxillary sinuses have lateral recesses and alveolar recesses inferiorly. The sphenoid sinuses are asymmetric air cells in the body of the sphenoid bone. Important surrounding structures include the maxillary division of CN5 in foramen rotundum laterally, the vidian nerve and artery in the vidian canal inferiorly, the optic nerves and sella superiorly, and the cavernous sinuses laterally. The sphenoid sinuses drain via their ostia into the SER. The OMU is a critical crossroads for drainage of the sinuses most affected by inflammatory disease (anterior ethmoid, maxillary, and frontal). Important components of the OMU include the ethmoid infundibulum, uncinate process, hiatus semilunaris, ethmoid bulla, and MM. P.IV(1):3
Approaches to Imaging Issues of the Sinus and Nose Congenital lesions can be classified as those presenting with nasal obstruction vs. nasal mass. Lesions presenting with nasal obstruction and no mass include pyriform aperture stenosis and choanal atresia. Frontonasal cephaloceles, dermoids, and extranasal gliomas present as extranasal masses. Frontoethmoidal cephaloceles, intranasal gliomas, and nasolacrimal duct mucoceles present with an intranasal mass. MR imaging can be very helpful for evaluating if there is a connection to the intracranial space. Rhinosinusitis (RS) is the most common pathology of the SN region. Acute RS is usually diagnosed clinically & does not require imaging. Always look for an odontogenic source of sinusitis if isolated maxillary sinus disease is identified. Because of the anatomy of the PS drainage pathways, predictable patterns of inflammatory disease exist based upon the point of obstruction. For example, obstruction of the MM would lead to disease in the ipsilateral frontal, anterior ethmoid, & maxillary sinuses. SER obstruction might lead to ipsilateral posterior ethmoid & sphenoid disease. Although uncommon, there are several forms of SN fungal disease. Mycetoma and allergic fungal sinusitis occur in immunocompetent patients and invasive fungal sinusitis (IFS) occurs in the immunocompromised or poorly controlled diabetics. It is important to note that IFS may appear mass-like at imaging. Granulomatous disease has a predilection for involving the nasal septum and turbinates. There are a wide variety of neoplasms of the SN cavities. Imaging features that favor a benignity include bone remodeling and well-defined margins vs. bone destruction and infiltrative margins. The site of origin may also be suggestive of histology. For instance, osteomas most often arise in the frontal and ethmoid sinuses, juvenile angiofibromas (JAF) arise in the posterior NC at the sphenopalatine foramen, inverted papillomas often arise along the lateral nasal wall, and esthesioneuroblastoma (ENB) typically arises near the CP. Squamous cell carcinoma is by far the most common SN malignancy and most often arises in the maxillary antrum. The imaging features of adenocarcinomas can be nonspecific, but they have a predilection for the ethmoid region. Three malignant neoplasms with a predilection for the NC include ENB, lymphoma, and melanoma. Clinical Implications The anatomy of the SN cavities is complex and highly variable. Technical advances, such as image guidance systems, have helped surgeons, particularly in the frontal & sphenoid sinuses. It is important to note that studies have shown a poor correlation between symptoms of RS and CT findings. The diagnosis of RS is a clinical one! Disease of the SN cavities often presents with nonspecific symptoms, such as nasal obstruction & discharge. Additional symptoms, such as epistaxis, may be indicative of a vascular lesion (JAF or ENB). Pain may also be caused by mucoceles or neoplasms, while paresthesias can be linked to malignancies such as adenoid cystic carcinoma. Clinically, lesions located within the NC can be evaluated with endoscopy. Lesions involving the sinuses are difficult to evaluate with scopes, so imaging is essential for characterization & determination of disease extent. Selected References 1. Beale TJ et al: Imaging of the paranasal sinuses and nasal cavity: normal anatomy and clinically relevant anatomical variants. Semin Ultrasound CT MR. 30(1):2-16, 2009 842
Diagnostic Imaging Head and Neck 2. Raghavan P et al: Magnetic resonance imaging of sinonasal malignancies. Top Magn Reson Imaging. 18(4):259-67, 2007 3. Aygun N et al: Imaging for functional endoscopic sinus surgery. Otolaryngol Clin North Am. 39(3):403-16, vii, 2006 Tables
Medial or dehiscent lamina papyracea Adenocarcinoma Middle turbinate Melanoma Concha bullosa Non-Hodgkin lymphoma Paradoxical curvature Sinonasal undifferentiated sarcoma Hypoplasia Adenoid cystic carcinoma Uncinate process Chondrosarcoma Pneumatized Osteosarcoma Deviated Rhabdomyosarcoma Fusion to middle turbinate or skull base Metastasis Atelectatic (approximates orbital floor)
Diagnostic Imaging Head and Neck
(Top) Sagittal graphic demonstrates the osseous anatomy of the lateral nasal wall. The superior turbinate & portions of the middle & inferior turbinates have been resected. The superior, middle, & inferior meati drain inferior to their respective turbinates. The ipsilateral frontal, anterior ethmoid, & maxillary sinuses ultimately drain into the middle meatus. The nasolacrimal duct drains into the inferior meatus. The sphenoid ostium is located along the anterior sphenoid sinus wall & drains into the SER. (Bottom) Coronal graphic of magnified right sinonasal region shows the important structures around the ostiomeatal unit. The vertically oriented uncinate process is bounded laterally by the ethmoid infundibulum, superiorly by the hiatus semilunaris, & medially by the middle meatus. The ethmoid bulla is the dominant anterior ethmoid cell located superior to the uncinate. The middle meatus drains beneath the middle turbinate. P.IV(1):5
Diagnostic Imaging Head and Neck
(Top) Sagittal graphic shows the frontal sinus drainage pathway. The frontal sinus narrows inferiorly to its ostium. Secretions drain through the ostium into the frontal recess (FR). The FR is not a true duct in that its walls are comprised of adjacent anatomy. In the graphic, the FR is bounded anteriorly by an agger nasi cell & posteriorly by the ethmoid bulla. Note that FR drainage may vary based upon the point of insertion of the uncinate process. (Bottom) Coronal graphic shows the important anatomy surrounding the sphenoid sinuses. The cavernous portions of the internal carotid arteries lie lateral & posterior to the sinuses. At the orbital apex, the optic nerve can be seen traversing the optic canal. Multiple cranial nerves pass through the superior orbital fissure into the orbit including CNs 3, 4, & 6 as well as the ophthalmic division on CN5. The maxillary division of CN5 in foramen rotundum & the vidian nerve are positioned lateral & inferior to the sinus, respectively. P.IV(1):6
Diagnostic Imaging Head and Neck
(Left) Coronal bone CT shows the paired frontal sinuses separated by the intersinus septum . The most anterior ethmoid-type cells, the agger nasi, can be seen . Notice the air-filled lacrimal sac on the left . (Right) Coronal bone CT shows the medial & lateral lamellae of the cribriform plate forming the roof of the nasal cavity. The fovea ethmoidalis forms the ethmoid sinus roof. Note the patent frontal recesses leading to the middle meati.
(Left) Sagittal CT reconstruction shows the frontal sinus drainage pathway. The sinus drains inferiorly into the frontal recess . A frontal cell is anterior to the recess & the ethmoid bulla is posterior . Note the middle & inferior turbinates. (Right) Axial T1WI MR shows the paired maxillary sinuses lateral to the nasal cavity. Note the inferior turbinates , midline nasal septum , & air-filled nasolacrimal ducts above the inferior meati.
Diagnostic Imaging Head and Neck
(Left) Sagittal CT reconstruction shows the nasolacrimal duct draining into the inferior meatus . Note the pterygopalatine fossa posterior to the maxillary sinus . (Right) Coronal bone CT at the level of the ostiomeatal units shows the uncinate processes , ethmoid bullae , & middle turbinates . They are pneumatized as is the right inferior turbinate. The middle meatus lies between the uncinate & middle turbinate. A retention cyst blocks the left maxillary ostium. P.IV(1):7
(Left) Sagittal CT reconstruction shows anterior & posterior ethmoid cells and the sphenoid sinus . The lateral attachment of the middle turbinate (basal lamella) is seen . Note the hiatus semilunaris . The palate is noted inferiorly . (Right) Axial bone CT shows the thin lamina papyracea separating the ethmoid air cells from the orbits. The sphenoid sinuses are separated by an intersinus septum. Note internal carotid arteries adjacent to the sinuses.
Diagnostic Imaging Head and Neck
(Left) Sagittal CT reconstruction shows the sphenoethmoidal recess bounded anteriorly by the most posterior ethmoid air cell & posteriorly by the sphenoid sinus . A retention cyst is seen in the sphenoid sinus . (Right) Coronal bone CT shows the sphenopalatine foramen connecting the nasal cavity to the pterygopalatine fossa (PPF) . The inferior orbital fissure extends from the PPF to the orbital apex. Note the planum sphenoidale above the sphenoid sinuses .
(Left) Sagittal CT reconstruction shows the sphenoid sinus ostium along the anterior wall of the sphenoid sinus. An agger nasi cell & the basal lamella are also seen. (Right) Coronal bone CT shows the important structures around the sphenoid sinuses. The vidian canals are noted along the sinus floors & the foramen rotundum is located laterally. The optic nerves lie medial to the anterior clinoids & the cavernous sinuses lie laterally .
Congenital Lesions Nasolacrimal Duct Mucocele > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section 1 - Nose and Sinus > Congenital Lesions > Nasolacrimal Duct Mucocele Nasolacrimal Duct Mucocele Michelle A. Michel, MD Key Facts Terminology Synonym: Congenital dacryocystocele Imaging 848
Diagnostic Imaging Head and Neck Well-defined, cystic, unilateral or bilateral medial canthal mass in contiguity with enlarged bony NLD in newborn Absent or minimal wall enhancement (unless infected) Coronal/sagittal reformatted images show contiguity of cyst at lacrimal sac with NLD and inferior meatus Top Differential Diagnoses Orbital dermoid and epidermoid Dacryocystocele, acquired Pathology Tears & mucus accumulate in nasolacrimal duct with imperforate Hasner membrane (distal duct obstruction) Clinical Issues Proximal lesion: Small, round, bluish, medial canthal mass identified at birth or shortly thereafter Distal lesion: Nasal airway obstruction with respiratory distress if bilateral Most common abnormality of infant lacrimal apparatus Diagnostic Checklist Cross-sectional imaging evaluates extent of lesion along lacrimal apparatus & excludes other sinonasal causes of respiratory distress in newborn
(Left) Axial bone CT in an infant shows well-circumscribed, low-density masses at the levels of the inferior meatus bilaterally consistent with nasolacrimal duct mucoceles. Note the position of the lesions relative to the inferior turbinates . (Right) Coronal T2WI MR in the same patient shows hyperintense signal in the mucoceles, not only at the inferior nasolacrimal ducts , but also at the level of the lacrimal sacs .
(Left) Axial CECT in an infant demonstrates a cystic mass with an enhancing rim in the medial right orbit consistent with a mucocele. There is associated enlarged lacrimal sac fossa . Note the normal left lacrimal sac fossa . (Right) Axial CECT in the same patient shows extension of the mucocele inferiorly to the level of the inferior meatus . The lesion obstructs the right nasal cavity at that level. 849
Diagnostic Imaging Head and Neck P.IV(1):9
TERMINOLOGY Abbreviations Nasolacrimal duct (NLD) mucocele Synonyms Congenital dacryocystocele Definitions Cystic dilatation of nasolacrimal apparatus secondary to proximal ± distal obstruction of NLD IMAGING General Features Best diagnostic clue Well-defined, cystic, unilateral or bilateral medial canthal mass in contiguity with enlarged bony NLD in newborn Location Anywhere from lacrimal sac to inferior aspect of NLD at inferior meatus Size Variable; 5-10 mm intranasal or medial orbital component CT Findings NECT Hypodense, thin-walled cyst medial canthus ± inferior meatus Cyst(s) communicate with enlarged NLD CECT Minimal wall enhancement (unless infected) MR Findings T1WI Hypointense, well-circumscribed mass at medial canthus ± inferior meatus T2WI Typically hyperintense due to fluid content T1WI C+ No or minimal wall enhancement around cyst Imaging Recommendations Best imaging tool Thin section axial bone CT Fast & ↓ need for sedation Rules out choanal atresia as cause of airway obstruction Protocol advice Coronal/sagittal reformats show contiguity of lacrimal sac cyst with large NLD in nasolacrimal canal & extension into inferior meatus DIFFERENTIAL DIAGNOSIS Orbital Dermoid and Epidermoid Lateral > medial canthus 50% fat density/intensity with thin rim enhancement ± calcification Dacryocystocele Acquired lacrimal sac cyst PATHOLOGY General Features Etiology Tears & mucus accumulate in nasolacrimal duct with imperforate Hasner membrane (distal duct obstruction) Nasolacrimal sac distension vs. anatomic variation compresses proximal valve CLINICAL ISSUES Presentation Most common signs/symptoms Principal presentation (proximal lesion) Small, round, bluish, medial canthal mass identified at birth or shortly thereafter Principal presentation (distal lesion) Nasal airway obstruction with respiratory distress if bilateral 850
Diagnostic Imaging Head and Neck Submucosal nasal cavity mass at inferior meatus Other signs/symptoms Tearing, crusting at medial canthus Preseptal cellulitis Clinical profile Infant with medial canthal mass ± nasal cavity mass Demographics Age Infancy; 4 days to 10 weeks typically Gender M < F = 1:3 Epidemiology Most common abnormality of infant lacrimal apparatus 3rd most common etiology in neonatal nasal obstruction 1st = mucosal edema, 2nd = choanal atresia Unilateral > bilateral Natural History & Prognosis 90% simple distal obstructions (congenital dacryostenosis) resolve spontaneously by age 1 Intervention recommended before infection occurs to prevent nasal airway obstruction, dacryocystitis, & permanent sequelae DIAGNOSTIC CHECKLIST Consider Cross-sectional imaging evaluates extent of lesion along lacrimal apparatus & excludes other sinonasal causes of respiratory distress in newborn SELECTED REFERENCES 1. Cavazza S et al: Congenital dacryocystocele: diagnosis and treatment. Acta Otorhinolaryngol Ital. 28(6):298-301, 2008 2. Wong RK et al: Presentation and management of congenital dacryocystocele. Pediatrics. 122(5):e1108-12, 2008 3. Rand PK et al: Congenital nasolacrimal mucoceles: CT evaluation. Radiology. 173(3):691-4, 1989
Choanal Atresia > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section 1 - Nose and Sinus > Congenital Lesions > Choanal Atresia Choanal Atresia Michelle A. Michel, MD Key Facts Terminology Congenital obstruction of posterior nasal apertures Imaging Unilateral or bilateral narrowing of posterior nasal cavity with membranous or osseous obstruction of choana Thickening of vomer Medial bowing of posterior maxilla Top Differential Diagnoses Choanal stenosis Pyriform aperture stenosis Nasolacrimal duct mucocele Nasal foreign body Pathology Unilateral CAt 1.6-2x as common as bilateral Bony-osseous (85-90%) Membranous (10-15%) Clinical Issues Bilateral CAt: Respiratory distress in newborn Unilateral CAt or stenosis: Chronic, purulent unilateral rhinorrhea with mild breathing obstruction Most common congenital abnormality of nasal cavity Isolated finding (25%) Associated with other anomalies (75%) Diagnostic Checklist Respiratory distress & nasal obstruction in newborn should be evaluated with thin section bone CT 851
Diagnostic Imaging Head and Neck
(Left) Axial bone CT in a newborn with unilateral choanal atresia on the left. There is a membranous atresia and fluid layers in the left nasal cavity. Note the associated thickening of the vomer posteriorly. (Right) Axial bone CT in an infant in respiratory distress with bilateral membranous choanal atresia. Note the soft tissue and fluid in the nasal cavities and the medialization of the maxillae (lateral nasal walls) posteriorly .
(Left) Axial NECT shows typical findings of unilateral choanal atresia. There is soft tissue within the left nasal cavity with apparent narrowing of the left choana . The contralateral nasal cavity is unremarkable. (Right) Axial bone CT in the same patient shows the bony stenosis of the left choanal opening to better advantage. The narrow opening is occluded by a membranous plug of tissue. P.IV(1):11
TERMINOLOGY Abbreviations Choanal atresia (CAt) Definitions Congenital obstruction of posterior nasal apertures IMAGING General Features Best diagnostic clue Unilateral or bilateral narrowing of posterior nasal cavity with membranous or osseous obstruction of choana Location Choanal openings: Posterior nasal cavity & nasopharyngeal junction 852
Diagnostic Imaging Head and Neck Size Choanal opening in newborn < 0.34 cm; vomer > 0.23 cm Morphology Medial bowing of posterior maxilla (lateral nasal walls) Thickened vomer Bone ± soft tissue membrane/plug obstructs choana CT Findings Bone CT Bony plate or soft tissue occludes choanal opening(s) Soft tissue in membranous atresia may be thin/strand-like or thick/plug-like Thickening of vomer, which may be fused to maxilla Medial bowing of posterior maxilla Nasal cavity filled with air, soft tissue, fluid, hypertrophied inferior turbinates Imaging Recommendations Best imaging tool High-resolution unenhanced bone CT Protocol advice Suction secretions from nasal cavity prior to scanning Perform supine with gantry angled 5° cephalad to palate High-resolution, edge enhancement bone filters helpful in delineating bone margins in partially ossified skull base Multiplanar reformations as needed Sagittal usually best plane for this 3D reconstructions may be helpful for clinical decision making & surgical planning DIFFERENTIAL DIAGNOSIS Choanal Stenosis More common than true CAt Part of spectrum of “choanal dysplasia” from stenosis to atresia Axial bone CT appearance Posterior nasal airway narrowed but not completely occluded Pyriform Aperture Stenosis Narrowed anterior nasal passage Axial bone CT appearance Narrowing of anterior & inferior nasal passage Thickened anteromedial maxilla Anterior nasal septum may be thinned Single central megaincisor may be present Brain evaluation for holoprosencephaly important Nasolacrimal Duct Mucocele Bilobed cystic masses in both nasolacrimal fossae & inferior meati Nasal Foreign Body Older patient with choanal stenosis or unilateral CAt PATHOLOGY General Features Etiology Pathogenesis remains elusive and unproven Failure of perforation of oronasal membrane (normally perforates by 7th week of gestation) Bony CAt: Incomplete canalization of choanae Membranous CAt: Incomplete resorption of epithelial plugs Molecular mechanisms in retinoic acid receptor development recently described in CAt pathogenesis Genetics Chromosomal abnormalities, single gene defects, deformations, and teratogens implicated Associated with chromosome 18, 12, 22, XO abnormalities Familial form exists Associated abnormalities Syndromic associations CHARGE syndrome
Diagnostic Imaging Head and Neck Coloboma, Heart defect, Choanal atresia, Retarded growth and development, Genitourinary abnormalities, Ear defects Choanal atresia in 100% of patients with CHARGE Acrocephalosyndactyly Amniotic band syndrome Apert syndrome Craniosynostosis Gut malrotations Crouzon disease Cornelia de Lange syndrome Fetal alcohol syndrome DiGeorge syndrome Treacher-Collins syndrome Unilateral CAt 1.6-2x as common as bilateral Staging, Grading, & Classification Choanal atresia types Bony-osseous (85-90%) Membranous (10-15%) Gross Pathologic & Surgical Features Membranous soft tissue or bony plate occludes choanal opening P.IV(1):12
CLINICAL ISSUES Presentation Most common signs/symptoms Bilateral choanal atresia: Respiratory distress in newborn Infants are obligate nasal breathers up to 6 months of age Aggravated by feeding Relieved by crying Unilateral choanal atresia or stenosis: Chronic, purulent unilateral rhinorrhea with mild breathing obstruction Other signs/symptoms Inability to pass nasogastric tube through nasal cavity beyond 3-4 cm despite aerated lungs on plain film Nasal stuffiness Grunting, snorting, low-pitched stridor Clinical profile Bilateral: Infant with respiratory distress Unilateral: Child/young adult with unilateral purulent rhinorrhea Demographics Age Bilateral atresia presents at birth Unilateral choanal atresia/stenosis may present in child/young adult Gender Incidence in males and females statistically equal Epidemiology CAt or choanal stenosis: Most common congenital abnormality of nasal cavity 1:5,000 to 8,000 live births CAt in isolation (25%) Unilateral cases more likely to be isolated CAt associated with other anomalies (75%) Bilateral cases more likely associated with specific disorders or multiple anomalies Natural History & Prognosis Bilateral CAt Diagnosed and treated in newborn period Unilateral CAt Not life-threatening May present later in childhood Prognosis excellent after surgical therapy 854
Diagnostic Imaging Head and Neck Some patients prone to re-stenosis Treatment Establish oral airway immediately to ensure proper breathing Membranous atresias may be perforated upon passage of NG tube Surgical treatment believed to be effective for alleviating respiratory symptoms Best surgical approach, use of endoscopic/laser-assisted techniques, adjuvant use of stents Use of antiproliferative agents debated Endoscopic approaches frequently used for simple membranous & bony atresias Minimizes traumatic injury leading to scarring & restenosis Bilateral bony atresias require transpalatal resection of vomer with choanal reconstruction Postoperative scar & incomplete resection of atresia plate best evaluated with bone CT DIAGNOSTIC CHECKLIST Consider Once airway is established, respiratory distress & nasal obstruction in newborn should be evaluated with thin section bone CT Image Interpretation Pearls Determine whether CAt unilateral or bilateral Look for associated anomalies in head & neck Reporting Tips Describe CAt as membranous or bony; unilateral or bilateral Comment on thickness of bony atresia plate SELECTED REFERENCES 1. Aslan S et al: Comparison of nasal region dimensions in bilateral choanal atresia patients and normal controls: a computed tomographic analysis with clinical implications. Int J Pediatr Otorhinolaryngol. 73(2):329-35, 2009 2. Burrow TA et al: Characterization of congenital anomalies in individuals with choanal atresia. Arch Otolaryngol Head Neck Surg. 135(6):543-7, 2009 3. Corrales CE et al: Choanal atresia: current concepts and controversies. Curr Opin Otolaryngol Head Neck Surg. Epub ahead of print, 2009 4. Hengerer AS et al: Choanal atresia: embryologic analysis and evolution of treatment, a 30-year experience. Laryngoscope. 118(5):862-6, 2008 5. Petkovska L et al: CT evaluation of congenital choanal atresia: our experience and review of the literature. Australas Radiol. 51(3):236-9, 2007 6. Uslu H et al: Bilateral choanal atresia; evaluation with scintigraphy: case report. Int J Pediatr Otorhinolaryngol. 70(1):171-3, 2006 7. Samadi DS et al: Choanal atresia: a twenty-year review of medical comorbidities and surgical outcomes. Laryngoscope. 113(2):254-8, 2003 8. Shah RK et al: Paranasal sinus development: a radiographic study. Laryngoscope. 113(2):205-9, 2003 9. Triglia JM et al: [Choanal atresia: therapeutic management and results in a series of 58 children] Rev Laryngol Otol Rhinol (Bord). 124(3):139-43, 2003 10. Holzmann D et al: Unilateral choanal atresia: surgical technique and long-term results. J Laryngol Otol. 116(8):6014, 2002 11. Faust RA et al: Assessment of congenital bony nasal obstruction by 3-dimensional CT volume rendering. Int J Pediatr Otorhinolaryngol. 61(1):71-5, 2001 12. Vanzieleghem BD et al: Imaging studies in the diagnostic workup of neonatal nasal obstruction. J Comput Assist Tomogr. 25(4):540-9, 2001 13. Behar PM et al: Paranasal sinus development and choanal atresia. Arch Otolaryngol Head Neck Surg. 126(2):155-7, 2000 14. Lowe LH et al: Midface anomalies in children. Radiographics. 20(4):907-22; quiz 1106-7, 1112, 2000 15. Hsu CY et al: Congenital choanal atresia: computed tomographic and clinical findings. Acta Paediatr Taiwan. 40(1):13-7, 1999 16. Black CM et al: Potential pitfalls in the work-up and diagnosis of choanal atresia. AJNR Am J Neuroradiol. 19(2):326-9, 1998 P.IV(1):13
Diagnostic Imaging Head and Neck
(Left) Axial NECT shows the typical features of unilateral choanal atresia. Fluid layers in the posterior nasal cavity on the left are due to a bony atresia . There is thickening of the vomer . (Right) Axial 3D reformatted image in the same patient shows the bony choanal atresia on the left with a widely patent choanal opening on the right . Three dimensional images can be very helpful to the referring clinicians for surgical planning.
(Left) Axial bone CT in a newborn with complex nasal anomalies shows bilateral CAt with aplasia of the right nasal cavity. There are fluid layers in the left nasal cavity & thickening of the vomer posteriorly . (Right) More inferior axial bone CT in the same patient shows fluid layering in the left nasal cavity anterior to the absent choanal opening. Note the absent right nasal cavity with the septum apposed to the lateral nasal wall . Incidental persistent craniopharyngeal canal is noted.
Diagnostic Imaging Head and Neck
(Left) Sagittal reformatted bone CT in the same patient shows the nonpatent left choanal opening and the layering fluid in the left nasal cavity . Incidental craniopharyngeal canal is shown. (Right) Axial bone CT shows a membranous, unilateral choanal atresia on the right side with layering fluid in the right nasal cavity. There are typical associated features, including thickening of the vomer and medialization of the posterior maxilla .
Nasal Glioma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section 1 - Nose and Sinus > Congenital Lesions > Nasal Glioma Nasal Glioma Michelle A. Michel, MD Key Facts Terminology Developmental mass of dysplastic neurogenic tissue sequestered & isolated from subarachnoid space “Glioma” is a misnomer as this is nonneoplastic tissue Extranasal glioma (ENG), intranasal glioma (ING) Imaging Well-circumscribed, soft tissue mass at superior nasal dorsum (ENG) or within nasal cavity (ING) with no connection to brain Multiplanar MR May show pedicle of fibrous tissue (not brain parenchyma) between ING & intracranial cavity Better than CT for differentiating NG from cephalocele or dermoid Gyral structure of gray matter rarely visible Commonly shows hyperintensity related to gliosis Top Differential Diagnoses Frontoethmoidal cephalocele Nasal dermal sinus Sinonasal solitary polyp Pathology Similar spectrum of congenital anomalies as frontoethmoidal cephaloceles Does not contain CSF contiguous with subarachnoid or intraventricular spaces Rarely associated with other brain or systemic anomalies Clinical Issues Usually identified at birth ENG: 60%, ING: 30%, other sites: 10% Treatment of choice is complete surgical resection
Diagnostic Imaging Head and Neck
(Left) Sagittal graphic of a nasal glioma shows a mass of dysplastic glial tissue along the nasal dorsum. Notice the absence of a connection to the intracranial contents. (Right) Sagittal T1WI MR of a newborn demonstrates a large intranasal glioma filling the right nasal cavity. No connection to the intracranial cavity by CSF-filled meninges or brain parenchyma is appreciated, helping to distinguish this lesion from an cephalocele.
(Left) Coronal NECT shows a well-defined, somewhat polypoid soft tissue mass , consistent with an intranasal glioma, within the left nasal cavity. The nasal septum is slightly deviated toward the right. No definite connection to the frontal lobe parenchyma is appreciated. (Right) Axial CECT shows a left-sided intranasal glioma widening the anterior nasal vault. P.IV(1):15
TERMINOLOGY Abbreviations Nasal glioma (NG) Extranasal glioma (ENG), intranasal glioma (ING) Synonyms Nasal cerebral heterotopia, glial heterotopia Definitions Developmental mass of dysplastic neurogenic tissue sequestered & isolated from subarachnoid space “Glioma” is misnomer as this is nonneoplastic tissue Best thought of as cephalocele without intracranial connection to brain IMAGING 858
Diagnostic Imaging Head and Neck General Features Best diagnostic clue Well-circumscribed, soft tissue mass at superior nasal dorsum (ENG) or within nasal cavity (ING) with no connection to brain Location Most occur at bridge of nose or in & around nasal cavity Usually off midline; right > left side ENG: Mass along nasal dorsum Glabella most frequent location ENG may also be found at medial canthus May be found in nasopharynx, mouth, pterygopalatine fossa (very rare) ING: Nasal cavity mass May be attached to concha of middle turbinate, nasal septum, or lateral nasal wall Other sites: Ethmoid sinus, palate, middle ear, tonsil, & pharynx Size 1-3 cm in diameter Morphology Well-circumscribed round, ovoid, or polypoid mass CT Findings NECT ENG: Well-circumscribed soft tissue attenuation mass (isodense to brain) located at glabella Superficial to point of fusion of frontal and nasal bones (fonticulus frontalis) Nasal bones may be thinned ING: Soft tissue attenuation mass within nasal cavity Typically high in nasal vault Fibrous pedicle may extend toward skull base but not intracranially Defect in cribriform plate (10-30%) Calcification rare CECT Typically no significant enhancement If intrathecal contrast used Fails to document connection of lesion to subarachnoid space MR Findings T1WI Predominantly mixed to low signal intensity mass Gyral structure of gray matter rarely visible T2WI Commonly shows hyperintensity related to gliosis No CSF around lesion connecting to subarachnoid space T1WI C+ Dysplastic tissue typically does not enhance “Perceived” enhancement at periphery of intranasal lesions may actually represent adjacent nasal mucosa Imaging Recommendations Best imaging tool Multiplanar MR May show pedicle of fibrous tissue (not brain parenchyma) between ING & intracranial cavity MR better than CT for differentiating NG from cephalocele or dermoid Avoids radiation to radiosensitive eye lenses in young patients Protocol advice Thin section sagittal T1 and T2 MR are important sequences Preoperative thin section axial bone CT with coronal reformatted images may also help in surgical planning Bone only without enhancement DIFFERENTIAL DIAGNOSIS Frontoethmoidal Cephalocele Frontonasal (FN) & nasoethmoidal (NE) cephaloceles Clinical: Congenital mass on or around bridge of nose (FN) or within nasal cavity (NE) Imaging: MR imaging shows connection to intracranial brain parenchyma 859
Diagnostic Imaging Head and Neck Nasal Dermal Sinus Clinical: Pit on tip or bridge of nose Imaging Associated dermoid or epidermoid along course from tip of nose to foramen cecum, anterior to crista galli Single or multiple Possible intracranial connection via sinus tract Sinonasal Solitary Polyps Clinical: Polyp is less firm, more translucent that ING Unusual < 5 years Imaging Typically inferolateral to middle turbinate (ING medial) Homogeneous ↑ T2 MR signal with thin enhancement of peripheral mucosa Orbital Dermoid and Epidermoid Clinical: Focal mass in medial orbit near nasolacrimal suture Imaging Dermoid: Fluid or fat density/signal intensity Epidermoid: Fluid density/signal P.IV(1):16
PATHOLOGY General Features Etiology Dysplastic, heterotopic neuroglial & fibrous tissue separated from brain during development of anterior skull or anterior skull base Similar spectrum of congenital anomalies as frontoethmoidal cephaloceles but does not contain CSF and is not contiguous with subarachnoid or intraventricular spaces ENG: Fonticulus frontalis (potential space prior to fusion of frontal & nasal bones) fuses prior to regression of dural diverticulum Dysplastic parenchyma sequestered over nasal bones/nasofrontal suture ING: Prenasal space (potential space prior to fusion of nasal bones with cartilaginous nasal capsule) fuses prior to regression of dural diverticulum Dysplastic parenchyma sequestered in nasal cavity Associated abnormalities Rarely associated with other brain or systemic anomalies Gross Pathologic & Surgical Features Firm, smooth mass Rarely recognized as brain tissue at surgery 10-30% attached to brain by a stalk of fibrous tissue through defect in or near cribriform plate Mixed extra-intranasal lesions connect through defect in nasal bone Microscopic Features Fibrous or gemistocytic astrocytes & neuroglial fibers Fibrous, vascularized connective tissue & sparse neurons Glial fibrillary acidic protein (GFAP) & S100 protein positive No mitotic features or bizarre nuclear forms CLINICAL ISSUES Presentation Most common signs/symptoms Extranasal glioma Congenital subcutaneous blue or red mass along nasal dorsum (glabella) Usually nonprogressive midfacial swelling Intranasal glioma Firm, polypoid submucosal nasal cavity mass Nasal obstruction & septal deviation may be present May be confused clinically with nasal polyp Other signs/symptoms No change in size with crying, Valsalva, or pressure on jugular vein (vs. frontoethmoidal cephalocele) ENG: Capillary telangiectasia may cover 860
Diagnostic Imaging Head and Neck ING: Respiratory distress; epiphora; may protrude through nostril Clinical profile Firm mass at glabella (ENG) or within nasal cavity (ING) in a newborn Demographics Age Identified at birth or within 1st few years of life Epidemiology Very rare lesion ENG: 60%, ING: 30%, other sites: 10% Natural History & Prognosis Grows slowly in proportion to adjacent tissue or brain if attached by pedicle May deform nasal skeleton, maxilla, or orbit May become infected, resulting in meningitis Complete resection is curative 10% recurrence rate with incomplete resection Treatment Treatment of choice is complete surgical resection ENG without intracranial connection removed via external incision with stalk dissection ING without intracranial connection may be removed endoscopically Less postoperative deformity than with craniotomy Rare mixed gliomas (extranasal & intranasal components) best treated with combined intranasal and extracranial approach DIAGNOSTIC CHECKLIST Consider Most important to differentiate NG from cephalocele Document lack of connecting brain tissue &/or contiguous CSF space Image Interpretation Pearls Must evaluate images for connection to intracranial cavity through skull base defect (cephalocele) Combined use of thin section MR & bone CT accomplishes this task Focus imaging to fronto-ethmoid area SELECTED REFERENCES 1. Husein OF et al: Neuroglial heterotopia causing neonatal airway obstruction: presentation, management, and literature review. Eur J Pediatr. 167(12):1351-5, 2008 2. Riffaud L et al: Glial heterotopia of the face. J Pediatr Surg. 43(12):e1-3, 2008 3. De Biasio P et al: Prenatal diagnosis of a nasal glioma in the mid trimester. Ultrasound Obstet Gynecol. 27(5):571-3, 2006 4. Hedlund G: Congenital frontonasal masses: developmental anatomy, malformations, and MR imaging. Pediatr Radiol. 36(7):647-62; quiz 726-7, 2006 5. Khanna G et al: Causes of facial swelling in pediatric patients: correlation of clinical and radiologic findings. Radiographics. 26(1):157-71, 2006 6. Huisman TA et al: Developmental nasal midline masses in children: neuroradiological evaluation. Eur Radiol. 14(2):243-9, 2004 7. Belden CJ et al: The developing anterior skull base: CT appearance from birth to 2 years of age. AJNR Am J Neuroradiol. 18(5):811-8, 1997 8. Barkovich AJ et al: Congenital nasal masses: CT and MR imaging features in 16 cases. AJNR Am J Neuroradiol. 12(1):105-16, 1991 P.IV(1):17
Diagnostic Imaging Head and Neck
(Left) Sagittal CECT demonstrates a mildly enhancing soft tissue lesion in the nasal cavity consistent with intranasal glioma . No connection is identified with what appears to be normal foramen cecum in a child of this age. (Right) Sagittal T1WI C+ MR in the same patient shows diffuse, slightly heterogeneous enhancement throughout the glioma .
(Left) Coronal FLAIR MR shows mixed signal intensity within an intranasal glioma . There is no connection to the left frontal lobe to suggest that a cephalocele is present. (Right) Axial T2WI MR shows a well-circumscribed intranasal glioma . It is slightly heterogeneous but similar in signal intensity to the brain parenchyma. No surrounding CSF can be seen around this glioma, a finding that is more indicative of an cephalocele.
Diagnostic Imaging Head and Neck
(Left) Axial T1WI C+ MR shows central enhancement within a large extranasal glioma. The lesion is located slightly off the midline. Enhancement is uncommon in these lesions. (Right) Axial T1WI C+ MR shows a well-defined extranasal glioma along the dorsum of the nose in the midline, with diffuse enhancement throughout the lesion. This degree of enhancement is a rare feature of nasal gliomas.
Nasal Dermal Sinus > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section 1 - Nose and Sinus > Congenital Lesions > Nasal Dermal Sinus Nasal Dermal Sinus Michelle A. Michel, MD Key Facts Terminology Defective embryogenesis of anterior neuropore resulting in any mixture of dermoid cyst, epidermoid cyst, &/or sinus tract in frontonasal region Imaging Midline location anywhere from nasal tip to anterior skull base at foramen cecum CT Bifid crista galli with large foramen cecum Fluid attenuation tract (sinus)/cyst or fat containing mass (dermoid) from nasal dorsum to skull base within nasal septum MR Fluid signal tract in septum from nasal dorsum to skull base (sinus) Focal low signal (epidermoid) or high signal (dermoid) mass found between tip of nose & apex of crista galli Top Differential Diagnoses Fatty marrow in crista galli Nonossified foramen cecum Frontoethmoidal cephalocele Nasal glioma Pathology Intracranial extension of nasal dermal sinus in 20% Associated craniofacial anomalies in 15% Clinical Issues Nasoglabellar mass (30%) Pit on skin of nasal bridge at osteocartilaginous nasal junction ± protruding hair
Diagnostic Imaging Head and Neck
(Left) Lateral graphic depicts a nasal dermal sinus with 2 dermoids. An extracranial dermoid is present just below a cutaneous nasal pit . An intracranial dermoid splits a bifid crista galli . (Right) Coronal bone CT demonstrates a nasal dermoid/epidermoid at the skull base. The low attenuation midline mass causes remodeling of the adjacent bone at the margins of the foramen cecum.
(Left) Sagittal T2WI MR in a 3-year-old boy with a bump on the tip of the nose shows a hyperintense sinus tract extending from the anterior skull base into the nasal septum. The features are characteristic of a dermal sinus. (Right) Axial NECT demonstrates a low-attenuation dermoid centered in the cartilaginous portion of the nasal septum. The mass is slightly higher in attenuation than adjacent fat. P.IV(1):19
TERMINOLOGY Abbreviations Nasal dermal sinus (NDS) Synonyms Nasal dermoid, nasal dermal cyst, anterior neuropore anomaly Definitions Defective embryogenesis of anterior neuropore resulting in any mixture of dermoid cyst, epidermoid cyst, &/or sinus tract in frontonasal region IMAGING General Features Best diagnostic clue CT 864
Diagnostic Imaging Head and Neck Bifid crista galli with large foramen cecum Fluid attenuation tract (sinus)/cyst or fat-containing mass (dermoid) from nasal dorsum to skull base within nasal septum MR Fluid signal tract in septum from nasal dorsum to skull base (sinus) Focal low signal (epidermoid) or high signal (dermoid) mass found between tip of nose & apex of crista galli Location Midline lesion anywhere from nasal tip to anterior skull base at foramen cecum Size 5 mm to 2 cm dermoid/epidermoid Morphology Ovoid mass ± tubular sinus tract CT Findings Bone CT Focal tract (sinus) or mass (dermoid or epidermoid) anywhere from nasal bridge to crista galli Fluid-density tract = sinus Fluid-density mass = epidermoid Fat-density mass = dermoid Signs of intracranial extension Large foramen cecum with bifid or deformed crista galli or cribriform plate MR Findings T1WI ↓ signal tract = sinus ↑ signal mass = dermoid ↓ signal mass = epidermoid T2WI ↑ signal in sinus, epidermoid, or dermoid Coronal plane shows septal lesions to best advantage DWI ↑ signal = epidermoid Susceptibility artifacts at skull base may obscure signal from epidermoid Imaging Recommendations Best imaging tool MR more sensitive for delineating sinus tract & characterizing epidermoid/dermoid lesions and intracranial extension Bone CT optimal for identifying skull base defect & crista galli deformity Protocol advice Imaging “sweet spot” is small & anterior Focus imaging from tip of nose to back of crista galli Inferior end of axial imaging is hard palate Contrast does not help with diagnosis CT Thin section (1-2 mm) bone & soft tissue axial & coronal CT MR Sagittal plane displays course of sinus tract from nasal dorsum to skull base Fat-suppressed images confirm fat presence in dermoids DWI imaging important additional sequence DIFFERENTIAL DIAGNOSIS Fatty Marrow in Crista Galli No nasoglabellar mass or pit on nose CT & MR otherwise normal Nonossified Foramen Cecum Closes postnatally in 1st 5 years of life Crista galli not deformed or bifid Frontoethmoidal Cephalocele Bone dehiscence is larger, involving a broader area of midline cribriform plate or frontal bone Direct extension of meninges, subarachnoid space ± brain can be seen projecting into cephalocele on sagittal MR Nasal Glioma 865