Microtia and Atresia
Forms of Microtia
“Microtia” is a generic term covering a broad spectrum of visible malformations of the external part of the ear affecting one or both ears. Part of the ear or the whole external ear can be affected by this. To better understand the different degrees of severity of the condition, microtia is described as being one of three grades.
The external ear is complete, but its shape is malformed. Protruding ears and less pronounced cup ears belong in this group.
Parts of the external ear are missing. Pronounced cup ears and so-called “small ears” belong to this group.
There is a barely visible external ear or there is not one at all.
In early pregnancy the human embryo has temporary gills. From these other parts of the face, the ears, ear canals and the middle ear develop. In this phase of development malformations can occur. This affects around 1 or 2 in 10,000 births.
The causes for microtia and atresia are largely unknown. Many parents are worried that they did something wrong during the pregnancy. However, on the whole these fears are ungrounded. External causes such as medication, alcohol or certain foodstuffs are not known to cause ear malformations. Only very few substances, for example Thalidomide, are known to be triggers.
The malformations can appear in an isolated manner, that is to say, without any other illnesses present or as part of a syndrome, which accounts for up to 60% of all cases. When it is a syndrome, this is described as the simultaneous appearance of different signs of illness of which the origins and development are not precisely known. The recognised syndromes with ear malformations include Goldenhar Syndrome (Oculo-Auriculo-Vertebral Dysplasia) and Treacher Collins Syndrome (also known as Franceschetti Syndrome).
Forms of Atresia
“Atresia” is a generic term covering different malformations of the ear canal and middle ear. The ability to hear is almost always affected. This is because speech, music and sounds cannot be correctly conveyed through the ear canal, ear drum and middle ear to the inner ear, which is normally intact.
Atresia also has various prominent characteristics. The ear canal can be almost normal, narrow or completely closed. The ear drum and middle ear can also be severely affected in different ways. The ear drum is frequently smaller and the small ear bones (ossicles) so altered in form and order that they are unable to perform any function at all.
Meaning of Hearing Loss
The ear consists of three parts:
1: The external, visible part with the ear and ear canal.
2: The middle part (middle ear) with ear drum and ossicles (small bones used for hearing).
3: The inner part (inner ear) with the cochlea and hair cells
Patients with microtia and atresia usually have an intact inner ear, as this part of the ear doesn’t develop from the pharyngeal arches. Therefore, the type of hearing impairment is mainly a pure conductive hearing loss and in such cases amounts to a loss of around 60 to 70 dB or around 75%. The affected ear is unable to detect many everyday sounds. If both ears are affected, this has a negative impact on the speech and general development of children with these conditions. They need a headband hearing aid in the first few weeks after birth.
Nowadays, unilateral hearing loss is assessed much differently than in the past. It is true that one ear is sufficient to allow normal speech development and maturation. However, in difficult listening situations, affected children quickly reach their performance limits. Difficult listening situations arise, for example, from other conversations in the same room, music or noise. For children, such situations occur for the first time at school and can only be partially compensated for. Directional hearing is also severely limited. It is assumed that in at least two-thirds of children with unilateral hearing loss, academic performance suffers. Therefore, we recommend early hearing improvement even in cases of unilateral hearing loss.
Acquired Ear Deformity
Acquired ear deformities arise mainly from accidents or tumour operations. These patients usually do not have a hearing impairment. The ear reconstruction follows the same principles as with congenital malformations. The method of reconstruction, however, must be adapted to the existing defect and the patient’s age. An individual treatment plan is discussed with the patient.