Microtia

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Microtia
Classification and external resources
Unilateral Grade III microtia (left side).
ICD-10 Q17.2
ICD-9 744.23
OMIM 600674
DiseasesDB 29876
eMedicine ped/3003 
For the orchid genus, see Microtis. For the vole genus, see Microtus.

Microtia (meaning 'Small ear') is a congenital deformity of the pinna (outer ear). 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 typically affected. There are four grades of microtia [2]:

  • 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 stenotic 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.

Grade III is most common, and can be corrected by surgery. Typically, testing is first done to determine if the inner ear is intact and hearing is normal. If hearing is normal, the next step (if a canal is not visible externally) will be to determine if a canal exists, by CT scan. For younger patients, this is done under sedation. Age when outer ear surgery can be attempted depends on the technique chosen (see below). The earliest age surgery can be attempted is age 3 for Medpor and 6 for Rib Cartilage Grafts. However the vast majority of surgeons, including the world experts in ear reconstruction recommend waiting until a later age, such as 8-10 when the ear is full adult size.

Contents

[edit] Options

There are two separate issues in microtia surgery:

  1. Auricular reconstruction to restore the visual appearance and form of the outer ear
  2. Repair of atresia or application of a bone-anchored hearing aid BAHA to restore hearing.

Unilateral deafness is not generally considered a serious disability, especially when the person is able to adjust to it from birth. In general, there is little to gain from an intervention to enable hearing in the microtic ear, except in bilateral microtia. However, children with untreated unilateral hearing loss are eight to ten times more likely to have to repeat a grade in school.[citation needed] If surgery or aids are 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. Age for BAHA implantation depends on whether you are in Europe (18 months) or the US (age 5).[citation needed] If the child is under the age for surgical implantation, the BAHA can be worn on a headband

For auricular reconstruction, there are four different options:

  1. Rib Cartilage Graft Reconstruction: This surgery should be performed only by specialists in the technique.{{Fact}] It involves sculpting the patient's own rib cartilage into the form of an ear. Although the cartilage is the patient's own living tissue, the reconstructed ear does not continue to grow as the child does. The procedure is therefore usually performed after 8 years of age, one reason being to ensure that the rib cage is large enough to provide the donor material necessary, but also so that the opposite (normal) ear has reached almost full adult size. This is a two-stage surgery. The major advantage of this surgery is that the patient's own tissue is used for the reconstruction.
  2. Reconstruct the ear using a polyethylene plastic implant: This is a two-stage surgery that can start around age 3. This surgery should only be performed by experts in the techniques involved as complications are difficult to correct.[citation needed]
  3. Ear Prosthesis: This surgery is ideally suited to those who are awaiting rib cartilage reconstruction (adhesive prosthesis) or in whom other techniques have failed (bone anchored prosthesis or adhesive prosthesis). A craniofacial prosthesis or 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 adhesive or with titanium 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. The optimal age to begin wearing an ear prosthesis is between the age of 6 and 9. The child should be mature enough to want the prosthesis and to help care for it.[1] A person with grade I & II microtia need not consider an ear prosthesis. A person with grade IV (anotia) is best suited for an ear prosthesis. A person with grade III construction has three options for reconstruction.
    1. Leave the skin tags for future surgical reconstructive purposes and make an adhesive retained prosthesis over the top of the existing ear. The advantage is that you can keep your reconstructive options open and you get more definition in the ear than a surgical approach. This allows you to try out the prosthetic approach without burning any bridges. It is also the least expensive approach. The disadvantage is that the ear is typically placed lower and more forward and tends to appear more bulky than the other ear. It will give you a good outline though. Placement is more difficult than prosthetics option '2'. If you like the look of the prosthesis and want to make it more permanent, you can proceed with option '3'.
    2. Remove the skin tags and use an adhesive retained ear. The advantage over prosthetic option '1' is that your prosthetic ear can be a near identical mirror image of your other ear. Placement is much easier as well because the skin is flat. The disadvantage is that options for surgical reconstruction are reduced by removing the skin tags.
    3. Remove the skin tags and simultaneously place the implants for a prosthesis. The visual results are very similar to prosthetic option '2'. The advantage is that placement of the ear becomes even easier and you eliminate the costs of adhesive and the associated daily care. The disadvantage is again that you limit your surgical reconstructive options significantly in placing the titanium screws.
  4. Soft tissue reconstruction: The reasoning for soft tissue reconstruction is that surgically reconstructed ears using rib-graft or implants are sensitive, though the sensation is not the same as for normal ears due to the transplant of skin from other areas of the body.

[edit] Complications

Aural atresia is commonly associated with microtia. Atresia occurs because patients with microtia may not have an external opening to the ear canal, though the cochlea and inner ear are usually present. The grade of microtia correlates to the development of the middle ear[2].

Microtia is usually isolated, but may occur in conjunction with hemifacial microsoma or Treacher-Collins Syndrome[3].

Microtia can cause difficulties with wearing headphones and glasses[4]. It is also occasionally associated with syndromes that can cause balance problems, kidney problems, 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 a prosthetic surgery, which means that it is not necessary, and hence is not covered by the insurance or support groups help.

Some patients may opt to not pursue surgery. This is usually because the child has already adapted to the condition, and unless is driven by self-esteem or cosmetic issues, may prefer to leave the condition unchanged.

[edit] References

  1. ^ Tanner PB, Mobley SR. External Auricular and Facial Prosthetics: A Collaborative Effort of the Reconstructive Surgeon and Anaplastologist. Auricular Surgery: Aesthetic and Reconstructive. Facial Plast Surg Clin North Am. 2006 May; 14(2):137-45, vi-vii.
  2. ^ Arch Otolaryngol Head Neck Surg - Abstract: Microtia grade as an indicator of middle ear development in aural atresia, August 1995, Kountakis et al. 121 (8): 885
  3. ^ PubMed Result
  4. ^ [1]

[edit] External links

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Congenital malformations and deformations of eye, ear, face and neck (Q10-Q18, 743-744)
Eyes
Ears
Microtia
Other or any combination
eye, ear, face and neck
See also non-congenital eye and ear
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