OVERVIEW

What is microtia?

Microtia is one of the common congenital malformations of the head and face.

During embryonic development, newborns may experience abnormal fusion of the first and second branchial arches due to genetic and environmental factors, leading to incomplete auricle development^[1].

It can manifest as varying degrees of auricular deformity, often accompanied by external auditory canal atresia or stenosis, middle ear malformations^[2], and may also involve ipsilateral mandibular, zygomatic, or temporal bone hypoplasia^[1].

Is microtia common?

The incidence of congenital microtia varies significantly worldwide.

In China, approximately 1.4 per 10,000 people are affected, with a male-to-female ratio of about 2:1. Right ear involvement is more common, though bilateral cases may also occur^[2].

What are the types of microtia?

Currently, the widely recognized clinical classification in China's plastic surgery community is the four-type system proposed by the Ear Reconstruction Center of the Plastic Surgery Hospital, Chinese Academy of Medical Sciences^[2]:

Type I: The auricle structure is mostly intact and recognizable. The concha is present but slightly small, with an overall smaller auricular contour. May coexist with cup ear or prominent ear deformities.
Type II: The auricle structure is partially incomplete but recognizable. The scaphoid fossa and triangular fossa are fused, with significant narrowing of the upper auricle and a noticeably smaller concha.
Type III: The auricle structure is unrecognizable, with irregular residual tissue. Often appears as peanut-shaped or sausage-like.
Type IV: Complete absence of the auricle, presenting only as small skin tags or scattered mound-like protrusions.

SYMPTOMS

What are the common manifestations of microtia?

It typically presents with varying degrees of auricular deformity, often accompanied by external auditory canal atresia or stenosis, middle ear malformation, and in severe cases, hearing impairment.

Some congenital microtia cases are associated with ipsilateral mandibular, zygomatic, or temporal bone hypoplasia and facial asymmetry. Occasionally, partial facial nerve dysfunction may occur due to ipsilateral facial nerve hypoplasia.

Microtia related to genetic syndromes, in addition to auricular deformity and hearing impairment, may also involve developmental abnormalities in other organ systems, such as craniofacial malformations, cardiac defects, limb anomalies, renal dysplasia, and spina bifida^[3].

What severe consequences can microtia cause?

Congenital microtia not only affects appearance but may also lead to hearing impairment due to external auditory canal atresia, stenosis, or middle ear malformation, potentially impacting early language development and social adaptation in affected children.

Microtia associated with genetic syndromes often involves developmental abnormalities in other organs and systems. It may impair vision, olfaction, circulation, respiration, digestion, reproduction, and urinary functions, hindering normal growth and development, or even posing life-threatening risks.

CAUSES

What causes microtia?

Congenital microtia results from a combination of genetic and environmental factors.

• Genetic factors:
  Genetic factors are one of the main causes of congenital microtia. It is often caused by single-gene defects or chromosomal abnormalities^[3], with autosomal dominant inheritance being the most common, and occasionally autosomal recessive or polygenic inheritance.

• Environmental factors:
  Improper medication use or exposure to toxic substances during pregnancy may lead to microtia in newborns. Additionally, advanced parental age, maternal gestational diabetes, and low birth weight are also associated risk factors^[2,4].

Who is at higher risk for microtia?

• Families with a history of microtia.
• Mothers living in high-altitude areas, having multiple pregnancies, or suffering from diabetes.
• Mothers exposed to drugs such as isotretinoin, thalidomide, ethanol, or mycophenolate mofetil during pregnancy.

Is microtia hereditary?

Congenital microtia can be inherited through autosomal dominant, autosomal recessive, or multifactorial inheritance patterns.

DIAGNOSIS

What tests are needed when microtia is suspected?

The examination for congenital microtia includes auricle examination, hearing tests, and a comprehensive physical examination to determine if there are defects in other organs or systems.

Sometimes, imaging tests are needed to assess whether there are abnormalities in the external, middle, or inner ear. If microtia is suspected in a newborn, specialists such as obstetricians and pediatricians should conduct early identification and diagnosis.

What should be noted during the examination?

Physical examinations, hearing tests, and imaging tests for congenital microtia are non-invasive and generally painless. However, if infants or young children cannot remain still or cooperate, sedation or hypnotic medication may be administered by a pediatrician to assist with imaging tests such as CT or MRI.

What conditions should microtia be differentiated from?

For cases where congenital microtia is not obvious, it usually needs to be differentiated from lop ear or prominent ear.

Lop ear or prominent ear: Prominent ear is often caused by incomplete folding of the antihelix of the auricle.

TREATMENT

Which department should I visit for microtia?

If microtia is suspected in a newborn, it is recommended to consult the pediatric department.

Children with varying degrees of auricular deformities can seek correction from the plastic surgery (reconstructive surgery) department. Those with concurrent hearing impairment or middle/inner ear deformities should also visit the otolaryngology department for evaluation and treatment.

How is microtia treated?

Mild auricular deformities without hearing impairment or other abnormalities may not require treatment if the child and family accept the appearance of the affected ear.

For newborns with mild auricular deformities, early non-surgical correction using ear molds is possible due to the malleability of ear cartilage shortly after birth.

For severe auricular deformities/absence, ear canal atresia/stenosis, or middle ear malformations, treatment may include auricular reconstruction, ear canal/middle ear reconstruction, auditory implants (e.g., cochlear implants, bone conduction devices), or corrective surgeries for concurrent craniofacial deformities.

Children with syndromic microtia require multidisciplinary systemic treatment targeting the underlying condition.

Can microtia be completely cured?

Congenital microtia without hearing loss can be considered cured after cosmetic surgery restores appearance. Cases with permanent hearing impairment requiring assistive devices are not fully curable.

Does microtia treatment require hospitalization?

Hospitalization isn't needed for ear mold correction alone. Surgical or comprehensive treatments typically require hospitalization based on severity.

What are the requirements for auricular reconstruction surgery?

Candidates should: have no other serious congenital/organic diseases; tolerate general anesthesia; and have adequately developed rib cartilage.

When should auricular reconstruction be performed?

For children with concurrent ear canal atresia or craniofacial deformities, surgical timing/sequence should be planned collaboratively by plastic surgeons and otolaryngologists.

For isolated microtia:

• Psychologically: Preschool age is ideal to minimize appearance-related distress.
• Physically: Age ~6 is optimal as ear size nears adulthood and rib cartilage matures. Delay beyond age 10 is discouraged.

What is the best framework material for auricular reconstruction?

Options include:

• Cartilage: Autologous/allo-rib cartilage
• Synthetic: Silicone, Medpor

Which surgical method should I choose?

Common techniques (Nagata, expansion flap methods, temporoparietal fascia flap) have respective advantages. Surgeons select based on residual ear size, skin condition, ear position, and healthy ear morphology.

Can auricular reconstruction be completed in one surgery?

No. Most cases require 2-3 staged procedures for structural stability and optimal aesthetics.

• Nagata method: Two surgeries (~10 days each)
• Expansion methods: Three surgeries (including tissue expander placement)

Will the reconstructed ear look completely natural?

Perfect symmetry is impossible. While subtle differences exist, reconstructed ears generally appear natural in social settings.

Will the reconstructed ear grow with age?

Autologous cartilage frameworks undergo normal metabolic growth. Since surgery occurs near adult ear size, significant size discrepancy is unlikely.

DIET & LIFESTYLE

What are the precautions after auricular reconstruction surgery? How to care for it?

• After rib cartilage harvest: Strengthen nutrition in the diet and supplement calcium; rest adequately in the early stage, avoid strenuous activities, and prevent excessive crying in children; get more sunlight exposure.

• After subcutaneous expander placement: Keep the local skin clean and avoid squeezing or bumping the expander.

  • Early expansion stage: Monitor for signs such as local skin redness, increased skin temperature, localized pain, swelling or pus formation around the expander, or exposure of the expander.
  • During the expansion process: If self-injection is required, strictly follow the doctor's instructions regarding injection frequency, speed, and volume. Do not increase the injection volume or frequency without authorization.
  • Late expansion stage: Observe for extensive skin paleness or excessive local tension after injection. If discomfort occurs, immediately withdraw fluid to relieve pressure and seek medical attention if necessary.

• After framework implantation and auricular formation: Avoid spicy or irritating foods and maintain a balanced diet; keep the local skin clean and avoid squeezing or bumping the reconstructed auricle; refrain from strenuous activities in the early stage.

PREVENTION

Can Microtia Be Prevented? How to Prevent It?

The occurrence of congenital microtia is influenced by various factors such as environment and genetics. By reducing and avoiding risk factors, the incidence of microtia can be prevented to some extent.

Specific measures include:

• Childbearing at an appropriate age, avoiding unhealthy habits during pregnancy planning, and supplementing nutrients reasonably.
• Pregnant women should register on time and undergo regular prenatal care, deformity screening, and check-ups.
• Maintain a healthy diet and moderate activity during pregnancy, with diabetic patients managing blood sugar levels properly.
• Avoid exposure to toxic and harmful substances during pregnancy, especially ethanol, isotretinoin, thalidomide, and mycophenolate mofetil.