Lawrence Swanson, Justin Brucker, CC4, Ashwani Sharma, MD
and P-L Westesson, MD, PhD, DDS
Clinical
Presentation: Patient is a 12-month-old,
full-term, child with congenital complete absence of the nose. Other clinical findings include a high-arched palate, micropthalmos, coloboma of the left iris, and possible right cataract. The pupils are equal in size and reactive to light, and extraocular movements are intact.
Imaging Findings: CT imaging demonstrates that the nasal passage, nasopharynx, and paranasal sinuses are not patent. The oropharynx demonstrates patency with visualized air within the mouth and extending down to the hypopharynx. The nasal bridge is flattened, and the protuberance of the nose is absent. The paranasal sinuses appear absent. The frontal and maxillary bones appear normal.
Coronal reformatted images demonstrate a curvilinear line in the midline inferior to the crista galli, suspicious for an encephalocoele (not shown). There are no other intracranial abnormalities.
Figure 1
Figure 2
Figures 1 and 2: Sagittal and frontal 3D imaging of child at one year of age.
Figure 3
Figure 4
Figures 3 and 4: 3D imaging of face with breathing tube at one year of age.
Figure 5: Sagittal CT with breathing tube and absent nasal prominence.
Figure 6: Axial CT; nasal prominence is absent.
Figure 7: Axial CT; bone structure is demonstrated at the level the maxillary sinus..
Figure 8: Sagittal CT; nasal bones are absent
Diagnosis:Congenital arhinia
Discussion: Arhinia, the congenital absence of the nose, is a rare condition resulting from an error in embryologic development [1]. As with many embryologic defects, the extent of the malformation varies from case to case. Of the few known cases, arhinia seems to associate with cleft or high-arched palate, micropthalmos, hypertelorism, coloboma of the iris, and maxillary hypoplasia. Arhinia may also appear as part of a constellation of congenital anomalies (eg. Treacher-Collins, Apert, Fraser, Binder, and Goldenhar syndromes) [2,5]. Not surprisingly, patients with arhinia also have anosmia. In fact, the olfactory bulbs, tracts and sulci do not develop -- possibly due to absence or failed migration of the olfactory receptor neurons. MRI can be used to visualize olfactory agenesis, but it should also be utilized to look for frontal encephalocoeles, which may occur with arhinia. MRI may also be useful in estimating the amount of room between the hard palate and floor of the anterior cranial fossa, when planning nasal canalization procedures [2]. Thin-slice, helical CT is the radiologic exam of choice, because it can be used to appreciate the size and extent of bone anomalies [1,2,4], and is therefore useful in surgical planning. Therefore, proper use of radiological imaging proves important during inspection for associated abnormalities and during the planning of case management.
Embryologic development of the nose begins after the proper migration of neural crest cells. The exact pathogenesis of arhinia remains unclear, but several mechanisms of improper development have been proposed. The condition appears to occur sporadically; there are few known familial cases, and most subsequent pregnancies are normal. In two cases, abnormalities in chromosome 9 were identified, but in most cases, no genetic abnormalities are apparent. A history of polyhydramnios or maternal diabetes may be associated with arhinia.
Diagnosis of arhinia is almost always made clinically at birth, but there are at least two known instances of a prenatal diagnosis. An early diagnosis can be quite beneficial, as it allows more time to prepare to manage the condition upon the child’s birth, and allows the family more time to cope with social and emotional complications.
Congenital arhinia has no clear etiology, although some cases have been linked to inversion or trisomy of chromosome 9, and to translocations between chromosomes 3 and 12 [2-5]. However, some affected individuals may be karyotypically normal, like our patient (46XX). Furthermore, patients often have no family history of congenital malformation, although familial arhinia has been reported. Non-genetic factors, such as maternal diabetes mellitus, hypertension, and toxemia during pregnancy may possibly play a role in the development of congenital arhinia [2,4]. However, most newborns with arhinia are the result of a normal, uncomplicated pregnancy and delivery [2,4].
The pathogenesis of congenital arhinia is similarly unclear, involving some abnormality during embryonic development of the nasal structures. Normally, nasal development takes place between the 3rd and 10th week of gestation. At first, the face (neural crest and mesodermal origin) consists of the frontal prominence, cephalic to the bilateral maxillary and mandibular processes, which are in turn separated by the primitive oral cavity (stomodeum). In week 4, between the frontal prominence and maxillary processes sit the nasal placodes, which are ovoid ectodermal thickenings surrounded by mesenchymal margins -- the medial and lateral nasal processes. After five weeks, the nasal placodes invaginate to form the nasal cavity, while the medial nasal processes fuse in the midline to form the structures of the nose and upper lip. During week 6, the maxillary processes fuse with the frontal process posteriorly to form the palatal shelves, separating the nasal cavity from the buccopharyngeal cavity. The nasal and buccopharyngeal elements fuse to form an oronasal membrane, which eventually degenerates to allow communication between both cavities. Epithelial plugs, which fill the posterior nasal cavity, are resorbed weeks later to give rise to the posterior choanae. Albernaz has proposed four different pathogenic mechanisms [1]: 1) absence of medial and lateral nasal processes, 2) overgrowth and premature fusion of the nasal processes, 3) aberrant neural crest migration, 4) failed epithelial plug resorption. Another possibility is failure of the nasal placode invagination [2].
Since newborns are obligate nose-breathers, the most immediate complications of simple arhinia are respiratory distress and feeding difficulties. Supportive care includes placement of orogastric and oropharyngeal tubes, or a tracheostomy. Surgical intervention, in order to improve functional and cosmetic outcomes, are usually deferred until around preschool age, in order to allow more facial growth and development to occur. However, there are reports of surgery being performed as early as 20 weeks [2] and planned for as late as 15 years of age [4]. Generally, patients with arhinia are reported to have normal intelligence and psychomotor development [2,4]. There is a case of autism and hypogonadotropic hypogonadism in one patient [3], which may suggest a failure of neuronal formation and/or migration from the nasal cavity, as is seen in Kallman's Syndrome (anosmia and hypogonadism). However, this does not seem to be typical of arhinia patients.
References:
Albernaz VS, Castillo M, Mukherji SK, Ihmeidan IH. Congenital arhinia. AJNR Am J Neuroradiol. 1996 Aug;17(7):1312-4. [Medline]
Olsen ØE, Gjelland K, Reigstad H, Rosendahl K. Congenital absence of the nose: a case report and literature review. Pediatr Radiol. 2001 Apr;31(4):225-32. [Medline]
Sato D, Shimokawa O, Harada N, Olsen OE, Hou JW, Muhlbauer W, Blinkenberg E, Okamoto N, Kinoshita A, Matsumoto N, Kondo S, Kishino T, Miwa N, Ariga T, Niikawa N, Yoshiura K. Congenital arhinia: molecular-genetic analysis of five patients. Am J Med Genet A. 2007 Mar 15;143(6):546-52. [Medline]
Shino M, Chikamatsu K, Yasuoka Y, Nagai K, Furuya N. Congenital arhinia: a case report and functional evaluation. Laryngoscope. 2005 Jun;115(6):1118-23. [Medline]
