Anotia

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Anotia
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Anotia ("no ear") describes a rare congenital deformity that involves the complete absence of the auricle, the outer projected portion of the ear, and narrowing or absence of the ear canal. This contrasts with microtia, in which a small part of the auricle is present. Anotia and microtia may occur unilaterally (only one ear affected) or bilaterally (both ears affected). This deformity results in conductive hearing loss, deafness.

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Ear development

Bilateral anotia in a 10-year-old boy, 1904 Deprivation Imbecile A.jpg
Bilateral anotia in a 10-year-old boy, 1904

Ear development begins in about the third week of human embryonic development, beginning with the formation of the otic placodes, an extension of the early hind brain. By the fourth week of development, the otic placodes invaginate, or sink inward forming pits which close themselves off for the outer surface ectoderm and begin forming the inner ear labyrinthe on the inside. Outer ear development begins in about the fifth week of human embryonic development. Upon the pharyngeal arches, auricle hillocks begin to form. By the seventh week, the three pairs of hillocks have enlarged differentiated and fused together to start forming the auricle, or outer portion of the ear. Throughout fetal development, the hillocks will move from the sides of the neck to the sides of the head. Simultaneously, in the seventh week of development, the auditory tube begins to form out of the tympanic membrane.

Processing sound

The human ear is divided into three sections. Each section has its own specialized function.

  1. The outer ear acts like a funnel and takes in the sound.
  2. The middle ear holds the tympanic membrane, or ear drum and several little bones that are moved by the sound waves that have entered the ear via the canal. These movements are very small, like vibrations and are transmitted to the inner ear.
  3. The inner ear contains a structure called the cochlea, which contains small hair- like cells that respond to sound information and transmits it via nerve impulses down the auditory nerve and to the brain, where they are processed.

Defects of the ear: anotia/microtia

The isolated cause, a cause not associated with a syndrome, of anotia or microtia is not known, though it is believed to be of genetic basis. Developmentally, anotia/microtia occurs when certain tissues associated with the auricle do not develop. This rare defect may occur as part of a syndrome or as an isolated abnormality.

Type I: External portion of the ear is small in size; auricle structure is normal

Type II: The auricle is in a hook or 'S' shape; external ear is only moderately abnormal.

Type III: Small amount of basic, soft tissue ear structure lacking cartilage; auricle is abnormal in appearance.

Type IV: Most severe type, anotia; all external structures of the ears are absent. Defects affecting the external ear such as the auricle results from malformation or suppression of the auricular hillocks, which are small swellings on the embryonic visceral arches or the beginnings of the external ears; the small swellings are derived from the first and second pharyngeal arches. Because the ears and the kidneys develop simultaneously, children with ear defects are often checked for kidney defects at birth.

"20% to 40% of children with microtia/anotia will have additional defects that could suggest a syndrome." [1]

Treacher-Collins syndrome: (TCS) A congenital disorder caused by a defective protein known as treacle, and is characterized by craniofacial deformities; malformed or absent ears are also seen in this syndrome. The effects may be mild, undiagnosed to severe, leading to death. Because the ear defects are much different in this disorder and not only affect the outer ear, but the middle ear as well, reconstructive surgery may not help with the child's hearing and in this case a bone-anchored hearing aid would be best. BAHA will only work, however if the inner ear and nerve are intact.

Goldenhar syndrome: A rare congenital birth defect that causes abnormalities of facial development. Also known as oculoauricular dysplasia. The facial anomalies include underdeveloped, asymmetric half of the face. The defect is capable of affecting tissue, muscle, and the underlying bone structure of the side of the face with the abnormality.

Ablepharon macrostomia syndrome  : (AMS) A rare genetic disorder characterized by various physical anomalies which affect the craniofacial area, the skin, the fingers, and the genitals.

Treatment

The treatment will vary with the different grades, but the most common is a surgical repair. The surgical option is cosmetic reconstruction of the external ear's normal shape and repair of the ear canal. In less severe cases, the reconstruction will be sufficient to restore hearing. In grades of anotia/microtia that affect the middle ear, the surgery with the use of a bone-anchored hearing aid (BAHA) will likely restore the hearing. The BAHA may be surgically implanted onto the skull which would allow for some hearing repair by conduction through the skull bone. "This allows sound vibrations to travel through bones in the head to the inner ear." [2]

BAHA: An implantable hearing device. It is the only hearing aid device that works via direct bone conduction. [3]

Related Research Articles

This is a glossary of medical terms related to communication disorders which are psychological or medical conditions that could have the potential to affect the ways in which individuals can hear, listen, understand, speak and respond to others.

<span class="mw-page-title-main">Ear</span> Organ of hearing and balance

An ear is the organ that enables hearing and body balance using the vestibular system. In mammals, the ear is usually described as having three parts: the outer ear, the middle ear and the inner ear. The outer ear consists of the pinna and the ear canal. Since the outer ear is the only visible portion of the ear in most animals, the word "ear" often refers to the external part alone. The middle ear includes the tympanic cavity and the three ossicles. The inner ear sits in the bony labyrinth, and contains structures which are key to several senses: the semicircular canals, which enable balance and eye tracking when moving; the utricle and saccule, which enable balance when stationary; and the cochlea, which enables hearing. The ear canal is cleaned via earwax, which naturally migrates to the auricle. The ears of vertebrates are placed somewhat symmetrically on either side of the head, an arrangement that aids sound localization.

<span class="mw-page-title-main">Auricle (anatomy)</span> Visible part of the ear that is outside the head

The auricle or auricula is the visible part of the ear that is outside the head. It is also called the pinna, a term that is used more in zoology.

<span class="mw-page-title-main">Treacher Collins syndrome</span> Human genetic disorder

Treacher Collins syndrome (TCS) is a genetic disorder characterized by deformities of the ears, eyes, cheekbones, and chin. The degree to which a person is affected, however, may vary from mild to severe. Complications may include breathing problems, problems seeing, cleft palate, and hearing loss. Those affected generally have normal intelligence.

<span class="mw-page-title-main">Conductive hearing loss</span> Medical condition

Conductive hearing loss (CHL) occurs when there is a problem transferring sound waves anywhere along the pathway through the outer ear, tympanic membrane (eardrum), or middle ear (ossicles). If a conductive hearing loss occurs in conjunction with a sensorineural hearing loss, it is referred to as a mixed hearing loss. Depending upon the severity and nature of the conductive loss, this type of hearing impairment can often be treated with surgical intervention or pharmaceuticals to partially or, in some cases, fully restore hearing acuity to within normal range. However, cases of permanent or chronic conductive hearing loss may require other treatment modalities such as hearing aid devices to improve detection of sound and speech perception.

<span class="mw-page-title-main">Primrose syndrome</span> Medical condition

Primrose syndrome is a rare, slowly progressive genetic disorder that can vary symptomatically between individual cases, but is generally characterised by ossification of the external ears, learning difficulties, and facial abnormalities. It was first described in 1982 in Scotland's Royal National Larbert Institution by Dr D.A.A. Primrose.

Otoplasty is a procedure for correcting the deformities and defects of the auricle, whether these defects are congenital conditions or caused by trauma. Otoplastic surgeons may reshape, move, or augment the cartilaginous support framework of the auricle to correct these defects.

Jacobsen syndrome is a rare chromosomal disorder resulting from deletion of genes from chromosome 11 that includes band 11q24.1. It is a congenital disorder. Since the deletion takes place on the q arm of chromosome 11, it is also called 11q terminal deletion disorder. The deletion may range from 5 million to 16 million deleted DNA base pairs. The severity of symptoms depends on the number of deletions; the more deletions there are, the more severe the symptoms are likely to be.

Atresia is a condition in which an orifice or passage in the body is closed or absent.

<span class="mw-page-title-main">Microtia</span> Medical condition

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 (isotretinoin) during pregnancy.

<span class="mw-page-title-main">Bone-anchored hearing aid</span>

A bone-anchored hearing aid (BAHA) is a type of hearing aid based on bone conduction. It is primarily suited for people who have conductive hearing losses, unilateral hearing loss, single-sided deafness and people with mixed hearing losses who cannot otherwise wear 'in the ear' or 'behind the ear' hearing aids. They are more expensive than conventional hearing aids, and their placement involves invasive surgery which carries a risk of complications, although when complications do occur, they are usually minor.

<span class="mw-page-title-main">Goldenhar syndrome</span> Rare birth defect; incomplete development of the face on one side

Goldenhar syndrome is a rare congenital defect characterized by incomplete development of the ear, nose, soft palate, lip and mandible on usually one side of the body. Common clinical manifestations include limbal dermoids, preauricular skin tags and strabismus. It is associated with anomalous development of the first branchial arch and second branchial arch.

In embryology, Carnegie stages are a standardized system of 23 stages used to provide a unified developmental chronology of the vertebrate embryo.

<span class="mw-page-title-main">Duane-radial ray syndrome</span> Medical condition

Duane-radial ray syndrome, also known as Okihiro syndrome, is a rare autosomal dominant disorder that primarily affects the eyes and causes abnormalities of bones in the arms and hands. This disorder is considered to be a SALL4-related disorder due to the SALL4 gene mutations leading to these abnormalities. It is diagnosed by clinical findings on a physical exam as well as genetic testing and imaging. After being diagnosed, there are other evaluations that one may go through in order to determine the extent of the disease. There are various treatments for the symptoms of this disorder.

Hearing loss with craniofacial syndromes is a common occurrence. Many of these multianomaly disorders involve structural malformations of the outer or middle ear, making a significant hearing loss highly likely.

Emanuel syndrome, also known as derivative 22 syndrome, or der(22) syndrome, is a rare disorder associated with multiple congenital anomalies, including profound intellectual disability, preauricular skin tags or pits, and conotruncal heart defects. It can occur in offspring of carriers of the constitutional chromosomal translocation t(11;22)(q23;q11), owing to a 3:1 meiotic malsegregation event resulting in partial trisomy of chromosomes 11 and 22. An unbalanced translocation between chromosomes 11 and 22 is described as Emanuel syndrome. It was first described in 1980 by American medical researchers Beverly S. Emanuel and Elaine H. Zackai, and a consortium of European scientists the same year.

<span class="mw-page-title-main">Human embryonic development</span> Development and formation of the human embryo

Human embryonic development or human embryogenesis is the development and formation of the human embryo. It is characterised by the processes of cell division and cellular differentiation of the embryo that occurs during the early stages of development. In biological terms, the development of the human body entails growth from a one-celled zygote to an adult human being. Fertilization occurs when the sperm cell successfully enters and fuses with an egg cell (ovum). The genetic material of the sperm and egg then combine to form the single cell zygote and the germinal stage of development commences. Embryonic development in the human, covers the first eight weeks of development; at the beginning of the ninth week the embryo is termed a fetus. The eight weeks have 23 stages.

<span class="mw-page-title-main">Michel aplasia</span> Medical condition

Michel aplasia, also known as complete labyrinthine aplasia (CLA), is a congenital abnormality of the inner ear. It is characterized by the bilateral absence of differentiated inner ear structures and results in complete deafness (anacusis). Michel aplasia should not be confused with michel dysplasia. It may affect one or both ears.

Facial femoral syndrome is a rare congenital disorder. It is also known as femoral dysgenesis, bilateral femoral dysgenesis, bilateral-Robin anomaly and femoral hypoplasia-unusual facies syndrome. The main features of this disorder are underdeveloped thigh bones (femurs) and unusual facial features.

<span class="mw-page-title-main">Thickened earlobes-conductive deafness syndrome</span> Medical condition

Thickened earlobes-conductive deafness syndrome, also known as Escher-Hirt syndrome, or Schweitzer Kemink Graham syndrome, is a rare genetic disorder which is characterized by ear and jaw abnormalities associated with progressive hearing loss. Two families worldwide have been described with the disorder.

References

  1. Schoenwolf, Gary C., and William J. Larsen. Larsen's Human Embryology. 4th ed. Philadelphia: Churchill Livingstone/Elsevier, 2009. p601-2. Print.
    • "Anotia/Microtia". Children and Youth with Special Health Needs. Minnesota Department of Health. Archived from the original on 4 January 2013. Retrieved 20 November 2012.
    • "Hopkins Hearing". Baha- implantable hearing device. Johns Hopkins Medicine. Retrieved 25 November 2012.

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