Microtia
Encyclopedia
Microtia, also called microtia-anotia, is a congenital deformity
where the pinna (outer ear) is very small and underdeveloped (microtia) or absent (anotia). It can be unilateral (one side only) or bilateral (affecting both sides). It occurs in 1 out of about 8,000–10,000 births. In unilateral microtia, the right ear is most commonly affected. It can occur as a complication of taking Accutane (isotretinoin) during pregnancy.
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 (usually) healthy inner ear—there is no ear canal, no eardrum, and the small ear bones (malleus/hammer, incus/anvil, and stapes/stirrup) 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 (as many as 19% in one study). 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 (hearing aids) 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
(beyond the scope of this discussion).
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 (e.g., FM system - see below) 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 (in children with unilateral aural atresia) 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 (the teacher wears a microphone, and the sound is transmitted to a speaker at the child's desk or to an ear bud or hearing aid the child wears), a bone conducting hearing aid, or conventional hearing aids. Age for BAHA implantation depends on whether you are in Europe (18 months) or the US (age 5). 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 (audiogram) and CT scan imaging.
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.
For auricular reconstruction, there are several different options:
is the underdevelopment of the middle ear and canal and usually occurs in conjunction with microtia. Atresia occurs because patients with microtia may not have an external opening to the ear canal, though. However, the cochlea and other inner ear structures are usually present. The grade of microtia usually correlates to the degree of development of the middle ear.
Microtia is usually isolated, but may occur in conjunction with hemifacial microsomia
, Goldenhar Syndrome
or Treacher-Collins Syndrome.
Microtia can cause difficulties with wearing headphones and glasses. It is also occasionally associated with kidney abnormalities (rarely life-threatening), and jaw problems, and more rarely, heart defects and vertebral deformities.
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. It must be stressed that many surgeons believe that ear canal reconstruction is unnecessary and overcomplicated and that very good hearing is possible with modern hearing aids which can be hidden under the skin.
There are several organizations which provide information and support to affected people.
In some countries, the outer ear reconstruction is considered as cosmetic surgery, which means that it is not necessary, and hence is not paid for by health insurance.
Congenital disorder
A congenital disorder, or congenital disease, is a condition existing at birth and often before birth, or that develops during the first month of life , regardless of causation...
where the pinna (outer ear) is very small and underdeveloped (microtia) or absent (anotia). It can be unilateral (one side only) or bilateral (affecting both sides). It occurs in 1 out of about 8,000–10,000 births. In unilateral microtia, the right ear is most commonly affected. It can occur as a complication of taking Accutane (isotretinoin) during pregnancy.
Classification
There are four grades of microtia:- Grade I: A slightly small ear with identifiable structures and a small but present external ear canal
- Grade II: A partial or hemi-ear with a closed off or stenoticStenosisA stenosis is an abnormal narrowing in a blood vessel or other tubular organ or structure.It is also sometimes called a stricture ....
external ear canal producing a conductive hearing loss - Grade III: Absence of the external ear with a small peanut vestige structure and an absence of the external ear canal and ear drum
- Grade IV: Absence of the total ear or anotia.
Treatment
Grade III microtia is most common, and can be corrected by surgery. 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 (Brain Stem Auditory Response 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 age when outer ear surgery can be attempted depends upon the technique chosen. The earliest is 7 for Rib Cartilage Grafts. However, some surgeons recommend waiting until a later age, such as 8-10 when the ear is closer to adult size.Surgical options
There are two separate issues regarding the ear:- Auricular reconstruction to restore the visual appearance and form of the outer ear
- Repair of atresia or application of a Bone Conduction Hearing Solution (BAHABone Anchored Hearing AidA Bone-anchored hearing aid is a type of hearing aid based on bone conduction. It is primarily suited to people who have conductive hearing losses, unilateral hearing loss and people with mixed hearing losses who cannot otherwise wear 'in the ear' or 'behind the ear' hearing aids...
) to restore hearing.
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 (usually) healthy inner ear—there is no ear canal, no eardrum, and the small ear bones (malleus/hammer, incus/anvil, and stapes/stirrup) 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 (as many as 19% in one study). 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 (hearing aids) 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
Cochlear implant
A cochlear implant is a surgically implanted electronic device that provides a sense of sound to a person who is profoundly deaf or severely hard of hearing...
(beyond the scope of this discussion).
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 (e.g., FM system - see below) 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 (in children with unilateral aural atresia) 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 (the teacher wears a microphone, and the sound is transmitted to a speaker at the child's desk or to an ear bud or hearing aid the child wears), a bone conducting hearing aid, or conventional hearing aids. Age for BAHA implantation depends on whether you are in Europe (18 months) or the US (age 5). 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 (audiogram) and CT scan imaging.
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.
For auricular reconstruction, there are several different options:
- Rib Cartilage Graft Reconstruction: This surgery may be performed by specialists in the technique. It involves sculpting the patient's own rib cartilage into the form of an ear. Because the cartilage is the patient's own living tissue, the reconstructed ear continues to grow as the child does. In order to be sure that the rib cage is large enough to provide the necessary donor tissue, some surgeons wait until the patient is 8 years of age.; however, some surgeons with more experience with this technique may begin the surgery on a child aged six. This surgery varies from two to four stages depending on the surgeon's preferred method. The major advantage of this surgery is that the patient's own tissue is used for the reconstruction.
- Reconstruct the ear using a polyethylene plastic implant (also called Medpor): This is a 1-2 stage surgery that can start at age 3 and can be done as an outpatient without hospitalization. Using the porous framework which allows the patient's tissue to grow into the material and the patient's own tissue flap, a new ear is constructed in a single surgery. A small second surgery is performed in 3–6 months if needed for minor adjustments. This surgery should only be performed by experts in the techniques involved.
- Ear Prosthesis: This surgery is ideally suited to those in whom other techniques have failed or are severely scarred by traumatic injuries such as burns. An auricular (ear) prosthesis is custom made by an anaplastologist to mirror the other ear. Prosthetic ears can appear very realistic. They require a few minutes of daily care. They are typically made of silicone, which is colored to match the patient's skin and can be attached using either adhesiveAdhesiveAn adhesive, or glue, is a mixture in a liquid or semi-liquid state that adheres or bonds items together. Adhesives may come from either natural or synthetic sources. The types of materials that can be bonded are vast but they are especially useful for bonding thin materials...
or with titaniumTitaniumTitanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....
screws inserted into the skull to which the prosthetic is attached with a magnetic or bar/clip type system. These screws are the same as the BAHA (Bone Anchored Hearing Aid) screws and can be placed simultaneously.
Related Conditions
Aural atresiaAtresia
Atresia is a condition in which a body orifice or passage in the body is abnormally closed or absent.Examples of atresia include:* Imperforate anus - malformation of the opening between the rectum and anus....
is the underdevelopment of the middle ear and canal and usually occurs in conjunction with microtia. Atresia occurs because patients with microtia may not have an external opening to the ear canal, though. However, the cochlea and other inner ear structures are usually present. The grade of microtia usually correlates to the degree of development of the middle ear.
Microtia is usually isolated, but may occur in conjunction with hemifacial microsomia
Hemifacial microsomia
Hemifacial microsomia is a congenital disorder that affects the development of the lower half of the face, most commonly the ears, the mouth and the mandible. It can occur on one side of the face or both. If severe it can lead to difficulties in breathing, obstructing the trachea and requiring a...
, Goldenhar Syndrome
Goldenhar syndrome
Goldenhar syndrome is a rare congenital defect characterized by incomplete development of the ear, nose, soft palate, lip, and mandible. It is associated with anomalous development of the first branchial arch and second branchial arch...
or Treacher-Collins Syndrome.
Microtia can cause difficulties with wearing headphones and glasses. It is also occasionally associated with kidney abnormalities (rarely life-threatening), and jaw problems, and more rarely, heart defects and vertebral deformities.
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. It must be stressed that many surgeons believe that ear canal reconstruction is unnecessary and overcomplicated and that very good hearing is possible with modern hearing aids which can be hidden under the skin.
There are several organizations which provide information and support to affected people.
In some countries, the outer ear reconstruction is considered as cosmetic surgery, which means that it is not necessary, and hence is not paid for by health insurance.
External links
- Craniofacial Anomalies Program at Children's Hospital Boston
- Microtia Repair
- Atresia Repair — University of Virginia
- Microtia Reconstruction at Cedars-Sinai
- Annual Atresia-Microtia Conference, October 11–12, 2009
- Goldenhar Family Support Group (UK)
- Microtia Australia