Heminasal Aplasia: Clinical Picture, Radiological Findings and Early “Temporary” Reconstruction with a Nasolabial Flap

Heminasal aplasia or hemi-arhinia is an extremely rare congenital malformation with the exact mechanism or etiology of its development still unknown. The rarity of this anomaly makes its reconstruction a surgical challenge with a diversity and controversy on the timing and technique of such reconstruction. We report a new case of hemi-arhinia which to the best of our knowledge is the seventieth reported case of congenital defect. The case was a female infant with absence of the lower 2/3 of the right side of the nose. The clinical and the CT scan manifestations of a case of right-sided hemi-arhinia together with the reconstructive plan of it are presented. We recommend early soft-tissue reconstruction using adjacent nasolabial flap without cartilage grafts to provide “temporary” correction of the disfigurement until the definitive reconstruction can be undertaken when the child grows up. This case was presented and operated upon in Plastic Surgery Dep., Faculty of Medicine, Sohag University, Sohag, EGYPT 82524 INTRODUCTION AND REVIEW OF LITERATURES Nasal hypoplasia ranging from underdevelopment or partial absence of parts to complete arhinia is the most frequently seen nasal anomalies [1]. Heminasal aplasia, hemi-arhinia or unilateral aplasia of the nose is a rare congenital malformation in which there is absence of half of the external nose together with a variable degree of abnormality in the internal anatomy of the nose as well as the adjacent facial structures. It imposes a major psychological burden to the parents and may have physiological impact on the child. The nose develops from the mesodermal frontonasal process and the two nasal placodes. The frontonasal process appears in the third to fourth week of gestation together with two bilateral ectodermal thickenings known as nasal placodes that grow caudally. During the fifth week of gestation, a central invagination, called the nasal pit, divides each nasal placode into a medial and a lateral nasal process. The nasal pits extend posteriorly to form the nasal cavity, which is separated from the oral cavity by a thin nasobuccal membrane. The nasobuccal membrane eventually ruptures at week 6 to form the posterior choanae. The epithelium around the forebrain thickens to become specialized olfactory sensory cells. The medial nasal processes from both sides fuse, forming the nasal septum and philtrum while the lateral processes develop into the external wall of the nose, the nasal bones, the upper lateral cartilages, the alae, and the lateral crura of the lower lateral cartilages. The failure of the development of nasal placodes probably lead to the congenital absence of nose [2]. Although the exact mechanism is unknown, several theories for the pathogenesis of arhinia were hypothesized. These theories include 1) failure of the medial and lateral nasal processes to grow, 2) premature fusion of the medial nasal processes, 3) lack of resorption of the nasal epithelial plug, and 4) abnormal migration of the neural crest cells [3,4]. Congenital arhinia may be in part induced by Chromosomal aberrations as some chromosomal change has been reported in several cases. The genetic analysis of five patients with complete arhinia identified a 19 Mb large deletion involving 3q11–q13 in one patient of them [5]. Another patient had and a translocation between chromosomes 3 and 12 [6]. In another report, one case was found to associate with inversion of chromosome 9 and another had mosaic of chromosome 9 [7]. Failure of the development of both nasal placodes results in complete nasal aplasia or arhinia while failure of one Heminasal Aplasia: Clinical Picture, Radiological Findings and Early “Temporary” Reconstruction with a Nasolabial Flap 2 of 6 placode leads to heminasal aplasia or hemi-arhinia [8]. Nasal anomalies rarely occur alone and are frequently associated with other coexistent craniofacial anomalies. They were classified into two major groups: 1. total arhinia, with absence of the nose and both olfactory nerves; 2. partial arhinia with presence of at least one nostril and one olfactory tract. Both groups can be seen without (a) or with (b) other craniofacial malformations [7]. Partial arhinia includes all the range from hypoplasia or absence of only an individual structure to a complete absence of the heminose. Few cases were reported with congenital absence of the columella, with the medial crura of the lower lateral cartilages and their softtissue covering were missing, while the remaining septum and other nasal structures were normal [9,10]. Isolated nasal bone agenesis or hypoplasia has also been reported [11,12]. Sixty-nine cases of hemi-arhinia have been reported, with the majority of these cases having an associated proboscis lateralis found on the same side of the missing half of the nose. In 1976, Mazzola reviewed 39 cases of them 27 cases were associated with proboscis lateralis [13]. In 1997, a review of 23 cases was published with the patients' data including gender, laterality and associated anomalies were presented [8]. In 2004, there was a report of five unrelated Brazilian patients [14] and another case reported in India [15]. In 2005, a new case from the USA was reported [16]. All reported cases are sporadic with no apparent gender or side preference.