International Journal of Pediatric Otorhinolaryngology
Microtia in Finland: Comparison of characteristics in different populations
Introduction
Microtia can be defined as a malformation of the auricle with varying severity ranging from minimal structural abnormalities to total absence of the earlobe. In the majority of patients microtia is combined with atresia or stenosis of the auditory canal, and there is a high correlation between the degree of microtia and the frequency of external and middle ear abnormalities [1]. There are several classifications for microtia, of which Marx's classification is still widely used. In Marx's classification, grade I represents an abnormally small earlobe with all anatomical structures distinguishable, and grade II is an abnormally small earlobe with some anatomical structures distinguishable and grade III shows only a rudiment of soft tissue, often a malformed lobule. Grade IV is commonly used to describe anotia, although it was not mentioned in the original classification by Marx [2].
The prevalence of microtia has been reported to vary from 0.83 to 17.4/10,000 [3], [4]. Microtia has been associated with numerous risk factors such as prenatal exposure to drugs [4], paternal age [4], high parity [3], [4], first parity [5], maternal diabetes [5], year of delivery [3], male gender [3], [6], race [3], [6], high maternal age [3], [7], altitude [8], urban area [9], low maternal education [6], multiple births [6], [7], and low birth weight [7]. Genetic factors are likely to have an effect at least in some patients with microtia; estimations of familial cases range from 2.9% to 33.8% [5], [10].
Microtia can be a feature in a wide variety of chromosomal abnormalities including the most common trisomy aneuploidies of chromosomes 13, 18 and 21. The London Dysmorphology Database of the London Medical Databases (version 1.0.1, http://www.lmdatabases.com) contains information on nearly 4000 dysmorphic and multiple congenital anomaly syndromes. Microtia can belong as a part to specific syndromes, and the keyword “small ears/microtia” refers to about 150 syndromes or conditions in this database. Many of these conditions are very rare: Treacher Collins, Nager, and Branchio-Oto-Renal syndromes can be mentioned as perhaps the most widely known examples.
Isolated microtia is suggested to represent a mild manifestation of the oculo-auriculo-vertebral spectrum (OAVS) [11], [12]. OAVS (Online Mendelian Inheritance in Man—database number OMIM164210) is a heterogeneous disorder likely to be a malformation involving the first and second branchial arch derivatives. The spectrum includes hemifacial microsomia and Goldenhar syndrome and has several alternative titles such as OAV dysplasia and facioauriculovertebral sequence. OAVS is highly variable, including anomalies of the ear, hemifacial microsomia, vertebral and skeletal defects and ocular abnormalities. In addition, patients with OAVS have been reported to have developmental delay and renal, cardiovascular, pulmonary and gastrointestinal malformations [13], [14]. There are several different classifications for OAVS, of which most recent is reported by Tasse et al. [15].
Microtia itself is mostly a cosmetic problem and the treatment is surgical. Surgical reconstruction of microtia is challenging. In most cases, multi-step earlobe reconstruction with autogenous rib cartilage is applied [16], [17], [18]. Microtia associated with congenital aural atresia requires prompt diagnosis, genetic counselling and an early assessment of hearing [19].
The aim of our study was to describe the prevalence and clinical features of microtia and OAVS in the Finnish population. Finland is one of the best-studied genetic isolates [20]. Our hypothesis was that due to the unique genetic features of the Finnish population the prevalence and phenotype of microtia might differ from the studies previously reported in other populations. In addition, we compared the characteristics of microtia and OAVS in different populations based on the literature.
Section snippets
Methods
We evaluated the clinical data of 200 microtia patients referred for surgical correction of the earlobe to the Cleft and Craniofacial Center of the Department of Plastic Surgery, Helsinki University Central Hospital during the years 1980–2005. Patients with chromosomal abnormalities and having or referring to a specific syndrome diagnosis were excluded from the study. As a result, 190 microtia patients with or without hemifacial microsomia or Goldenhar syndrome likely to belong to the
Results
Of the 190 Finnish microtia/OAVS patients seen at the Helsinki University Central Hospital, 58% were male (111/190). 88.4% (168/190) had unilateral microtia. In 59.5% (113/190) of patients the affected ear was right-sided, 28.9% left-sided (55/190) and 11.5% bilateral (22/190). In 93% (175/188) of patients microtia was associated with atresia or stenosis of the auditory canal. 33.5% (56/167) of patients had preauricular tags, of which 22.2% were ipsilateral, 7.2% contralateral and 4.2%
Discussion
There are several patient-based studies on the characteristics of microtia/OAVS patients. The patient material is well-defined and relatively large, ranging from 53 [15] to 592 [21] cases. There is clear male predominance in all the reports, ranging from our 58% in Finland to 64.7% in Japan [21]. There are marked differences in the laterality of microtia, prevalence of accompanying aural atresia, and prevalence of auricular tags. Tasse et al. reported the frequency of unilateral microtia to be
Conflict of interest
The authors do not have any financial or personal relationships that could influence this work.
Acknowledgments
We acknowledge the financial support from the Päivikki and Sakari Sohlberg’ Foundation, from the Finska Läkaresällskapet, from the Stiftelsen Dorothea Olivia, Karl Walter and Jarl Walter Perklens Minne and from the Helsinki University Central Hospital (HUCH EVO).
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