Microtia
Microtia is a congenital deformity where the auricle is underdeveloped. A completely undeveloped auricle is referred to as anotia. Because microtia and anotia have the same origin, it can be referred to as microtia-anotia. Microtia can be unilateral or bilateral. Microtia occurs in 1 out of about 8,000–10,000 births. In unilateral microtia, the right ear is most commonly affected. It may occur as a complication of taking Accutane during pregnancy.
Classification
According to the Altman-classification, there are four grades of microtia:- Grade I: A less than complete development of the external ear with identifiable structures and a small but present external ear canal.
- Grade II: A partially developed ear with a closed stenotic external ear canal producing a conductive hearing loss.
- Grade III: Absence of the external ear with a small peanut-like vestige structure and an absence of the external ear canal and ear drum. Grade III microtia is the most common form of microtia.
- Grade IV: Absence of the total ear or anotia.
Causes and risk factors
Microtia is also feature of many conditions and syndromes:
- 46,XY sex reversal 4
- Alpha thalassemia-X-linked intellectual disability syndrome
- Autosomal recessive faciodigitogenital syndrome
- Autosomal recessive spondylometaphyseal dysplasia, Megarbane type
- Bartsocas-Papas syndrome 1
- Bilateral microtia-deafness-cleft palate syndrome
- Blepharophimosis - intellectual disability syndrome, MKB type
- Blepharophimosis - intellectual disability syndrome, Ohdo type
- Branchial arch abnormalities, choanal atresia, athelia, hearing loss, and hypothyroidism syndrome
- Branchiooculofacial syndrome
- Branchiootorenal syndrome 1
- CHARGE association
- Chromosome 1p36 deletion syndrome
- COG1 congenital disorder of glycosylation
- Complete trisomy 21 syndrome
- Diamond-Blackfan anemia 10
- Diamond-Blackfan anemia 14 with mandibulofacial dysostosis
- Diamond-Blackfan anemia 15 with mandibulofacial dysostosis
- Dilated cardiomyopathy-hypergonadotropic hypogonadism syndrome
- Ectrodactyly, ectodermal dysplasia, and cleft lip-palate syndrome 1 and 3
- Epidermolysis bullosa simplex 5C, with pyloric atresia
- Epidermolysis bullosa, junctional 6, with pyloric atresia
- Fanconi anemia complementation group F
- Fanconi anemia complementation group L
- Fine-Lubinsky syndrome
- Gaucher disease perinatal lethal
- Goldenhar syndrome
- Hemifacial atrophy
- Hennekam lymphangiectasia-lymphedema syndrome 2
- Holoprosencephaly 12 with or without pancreatic agenesis
- Holoprosencephaly 13, X-linked
- Hypertelorism, microtia, facial clefting syndrome
- Intellectual developmental disorder with dysmorphic facies and behavioral abnormalities
- Intellectual developmental disorder with macrocephaly, seizures, and speech delay
- Intellectual disability, autosomal dominant 1, 43, and 53
- Intrauterine growth restriction, metaphyseal dysplasia, adrenal hypoplasia congenita, genital anomalies, and immunodeficiency
- Isotretinoin-like syndrome
- Larsen-like syndrome, B3GAT3 type
- Mandibulofacial dysostosis with alopecia
- Mandibulofacial dysostosis-macroblepharon-macrostomia syndrome
- Mandibulofacial dysostosis-microcephaly syndrome
- Meier-Gorlin syndrome
- Methylmalonic aciduria and homocystinuria type cblF
- Microcephalic osteodysplastic primordial dwarfism type II
- Microcephaly 6, primary, autosomal recessive
- Microtia-Anotia
- Microtia-eye coloboma-imperforation of the nasolacrimal duct syndrome
- Mitochondrial complex 3 deficiency, nuclear type 11
- Myhre syndrome
- Neurodevelopmental disorder with relative macrocephaly and with or without cardiac or endocrine anomalies
- Neurodevelopmental disorder with spasticity and poor growth
- Neurodevelopmental disorder with speech impairment and dysmorphic facies
- Neurodevelopmental disorder-craniofacial dysmorphism-cardiac defect-hip dysplasia syndrome due to a point mutation
- Oculoauriculovertebral spectrum with radial defects
- Osteodysplastic primordial dwarfism, type 1
- Osteopathia striata with cranial sclerosis
- Pallister-Hall syndrome
- Parietal foramina with cleidocranial dysplasia
- Paternal uniparental disomy of chromosome 14
- Periventricular nodular heterotopia 9
- Phocomelia-ectrodactyly-deafness-sinus arrhythmia syndrome
- Primordial dwarfism-immunodeficiency-lipodystrophy syndrome
- Progressive spondyloepimetaphyseal dysplasia-short stature-short fourth metatarsals-intellectual disability syndrome
- Saethre-Chotzen syndrome
- Scalp-ear-nipple syndrome
- Seckel syndrome 7
- Short stature and Facioauriculothoracic malformations
- Short ulna-dysmorphism-hypotonia-intellectual disability syndrome
- Skin creases, congenital symmetric circumferential, 2
- Spondyloepiphyseal dysplasia with congenital joint dislocations
- Spondyloepiphyseal dysplasia, Cantu type
- Townes-Brocks syndrome 1 and 2
- Treacher Collins syndrome 1 to 3
- Trichohepatoenteric syndrome 1
- Triglyceride storage disease with ichthyosis
- X-linked intellectual disability, van Esch type
- Yunis-Varon syndrome
Diagnosis
Treatment
The goal of medical intervention is to provide the best form and function to the underdeveloped ear.Hearing
Typically, testing is first done to determine the quality of hearing. This can be done as early as in the first two weeks with a BAER test. At age 5–6, CT or CAT scans of the middle ear can be done to elucidate its development and clarify which patients are appropriate candidates for surgery to improve hearing. For younger individuals, this is done under sedation.The hearing loss associated with congenital aural atresia is a conductive hearing loss—hearing loss caused by inefficient conduction of sound to the inner ear. Essentially, children with aural atresia have hearing loss because the sound cannot travel into the healthy inner ear—there is no ear canal, no eardrum, and the small ear bones are underdeveloped. "Usually" is in parentheses because rarely, a child with atresia also has a malformation of the inner ear leading to a sensorineural hearing loss. Sensorineural hearing loss is caused by a problem in the inner ear, the cochlea. Sensorineural hearing loss is not correctable by surgery, but properly fitted and adjusted hearing amplification generally provide excellent rehabilitation for this hearing loss. If the hearing loss is severe to profound in both ears, the child may be a candidate for a cochlear implant.
Unilateral sensorineural hearing loss was not generally considered a serious disability by the medical establishment before the nineties; it was thought that the afflicted person was able to adjust to it from birth. In general, there are exceptional advantages to gain from an intervention to enable hearing in the microtic ear, especially in bilateral microtia. Children with untreated unilateral sensorineural hearing loss are more likely to have to repeat a grade in school and/or need supplemental services than their peers.
Children with unilateral sensorineural hearing loss often require years of speech therapy in order to learn how to enunciate and understand spoken language. What is truly unclear, and the subject of an ongoing research study, is the effect of unilateral conductive hearing loss on scholastic performance. If atresia surgery or some form of amplification is not used, special steps should be taken to ensure that the child is accessing and understanding all of the verbal information presented in school settings. Recommendations for improving a child's hearing in the academic setting include preferential seating in class, an FM system, a bone-anchored hearing aid, or conventional hearing aids. Age for BAHA implantation depends on whether the child is in Europe or the US. Until then it is possible to fit a BAHA on a softband
It is important to note that not all children with aural atresia are candidates for atresia repair. Candidacy for atresia surgery is based on the hearing test and CT scan imaging. If a canal is built where one does not exist, minor complications can arise from the body's natural tendency to heal an open wound closed. Repairing aural atresia is a very detailed and complicated surgical procedure which requires an expert in atresia repair. While complications from this surgery can arise, the risk of complications is greatly reduced when using a highly experienced otologist. Atresia patients who opt for surgery will temporarily have the canal packed with gelatin sponge and silicone sheeting to prevent closure. The timing of ear canal reconstruction depends on the type of external ear repair desired by the patient and family. Two surgical teams in the USA are currently able to reconstruct the canal at the same time as the external ear in a single surgical stage.
In cases where a later surgical reconstruction of the external ear of the child might be possible, positioning of the BAHA implant is critical. It may be necessary to position the implant further back than usual to enable successful reconstructive surgery – but not so far as to compromise hearing performance. If the reconstruction is ultimately successful, it is easy to remove the percutaneous BAHA abutment. If the surgery is unsuccessful, the abutment can be replaced and the implant re-activated to restore hearing.