Microtia Surgery: Underdeveloped Ear Reconstruction

Introduction

Microtia is a congenital deformity of the outer ear in which the ear does not fully develop. The word microtia is derived from the Latin words micro meaning little, and otia, meaning ear, therefore little ear. Microtia ears appear smaller and often contain a tiny peanut-shaped lobe. The inner ear usually functions appropriately, and the main problem lies in sound conduction to the inner ear. Therefore, reconstruction of the outer ear is done via surgery, which needs great surgical expertise to restore hearing.

What Is the Incidence Rate of Microtia?

Microtia occurs in 1 to 10 per 10000 births, although it usually depends on ethnic background and related syndromes. It is usually unilateral in more than 90 percent of cases and more commonly in the right ear, and males have a 30 percent higher chance of microtia than females. Ethnic groups such as Andeans, Native Americans, Asians, and Hispanics are more prone to this condition.

What Are the Grades of Microtia?

• Grade I - The ear is usually smaller than normal, but all the necessary functions of a normal ear are present. However, it may involve minor alterations in shape or form.

• Grade II - Usually, the upper half of the ear is severely affected, and the lower half appears normal. In addition, some of the features of the ear might be missing. Grade II microtia is called conchal-type microtia, as the ear canal may be absent or very narrow (canal stenosis).

• Grade III - This is the most common type of microtia, also called lobular type microtia, as the only feature remaining of the ear is just a tiny peanut-shaped ear lobe. Moreover, the ear canal is absent (aural atresia).

• Grade IV - This is the rear occurrence in which the complete absence of the external ear can be seen and is called anotia.

What Are the Causes of Microtia?

In the majority of the cases, the actual cause of microtia is not known. It is a rare condition and cannot be found in prenatal ultrasound. The possible cause of microtia includes -

• One of the reasons may be blockage of the blood supply due to pressure as a result of the positioning of the fetus against the inside of the womb or from the umbilical cord during the first trimester (from week one to week twelve).

• A drop in oxygen levels during pregnancy within the first trimester may cause the abnormal development of the ear. During the first trimester, kidneys, heart, and ears develop simultaneously. Therefore anomalies can be seen in all of these systems as the organs get affected.

• Abuse of drugs or alcohol during pregnancy can cause microtia and ear canal atresia (absence of ear canal). Drugs and alcohol can cause multiple medical issues, and microtia is one of them.

• Microtia can be seen in fetal alcohol syndrome and due to medications like Accutane (Isotretinoin) and Methamphetamines during pregnancy.

What Is Microtia Surgery, and Why Is It Done?

Ear surgery or microtia reconstruction surgery is done to repair or rebuild the external part of the ear. These surgeries may be done in cases with irregularly developed ears present at birth (congenital defect) or ear damaged by cancer surgery or trauma.

Ear reconstruction is usually done under the following conditions that affect the development of the outer ear -

• Micrtia (underdeveloped ear).

• Anotia (missing ear).

• Folded ear (constricted ear).

• Part of an ear is buried under the skin on the side of the head (cryptotia).

• Damaged ear due to trauma such as burns.

• Damaged ear due to cancer treatment.

• Stahl’s ear (pointed ear with multiple skin folds).

What Are the Different Surgical Procedures for Microtia?

Various surgical procedures can be done to reconstruct the damaged ear, which includes -

1. Rib Graft Reconstruction -

The malformed ear is reconstructed using the cartilage taken from the rib of the patient. This is done in two stages -

• Stage One - At first, a small five to six centimeters horizontal incision is made in the anterior chest wall, and rib cartilages are harvested, leaving the outer layer (perichondrium). After that ear, the framework is reconstructed, and a skin pocket is created at the designated position. The reconstructed framework is placed into it, and the skin is sutured.

• Stage Two - After six months the ear is lifted from the area and it is sutured away from the head. The elevation is maintained by another piece of cartilage which is fixed behind the ear. A thin layer of vascularized tissue covers the framework to create a natural appearance. The tissue can be taken from under the scalp skin (temporoparietal fascial flap).

Advantages -

• No complications, as the body's own tissues are used.

• The prognosis is excellent.

• A reconstructed ear can withstand trauma very well.

Disadvantages -

• The surgery duration is extended.

• Two or more surgical stages are required.

• The prognosis usually depends upon the skills and experience of the surgeon.

2. Medpor Graft Surgical Reconstruction -

This surgery uses a synthetic pre-made porous polyethylene framework that does not require cartilage from the rib. The implant can be covered with the tissue taken from the scalp (temporalis muscle fascia). This can be done under one stage and as early as three years of age.

Advantages -

• Only requires one stage and can be done at an early age.

• Does not require a donor site and eliminates pain and healing of the donor site.

Disadvantages -

• This technique-sensitive surgery is not that commonly performed.

• Any trauma can lead to an infection which can cause the complete removal of the medpor implant.

• The implant does not give the normal sensation to the ear as compared to rib cartilage reconstruction.

• There are higher chances of fracture and disfigurement in the case of a medpor implant.

3. Prosthetic Reconstruction -

A prosthetic implant can be made to look like a natural ear. For this, titanium implants are drilled into the skull. Abutments or heads are given on which prosthetic ears can be fixed.

Advantages -

• An ear prosthetic is made from a material that feels and looks like the skin or a natural ear. It appears good and mirrors the opposite ear.

• This is a less painful surgery and can be done in one stage.

• A patient can even swim with the prosthetic.

Disadvantages -

• This method usually goes with patient compliance as some people do not like the idea of prosthetics that come on and off as compared to permanently reconstructed ear sutures directly.

• The implants have the chance of causing a skin infection, and the prosthesis may wear down with time and need to be replaced.

What Are the Post-operative Instructions?

It is common that the patient feels problems like pain, swelling, bleeding, and itching. The patient has been prescribed medicines for these problems. Precautions that should be taken after microtia surgery include -

• The patient should not sleep on the side of the operation.

• Contact sports should be avoided for at least three months.

• Pressure should not be applied to the operated area.

• The results of the surgeries usually depend upon the expertise of the surgeon.

What Are the Risks Associated With Microtia Surgery?

Risks are constantly involved with any surgery, such as bleeding, swelling, infection, or reaction to anesthesia. Some of the risks associated with microtia surgery include the following -

• Scarring - The scars from this surgery are permanent and often hidden behind the ear.

• Skin Breakdown - The skin used to cover the ear framework may break down, exposing the implant or cartilage underneath it. Therefore another surgery might have to be done to correct this.

• Scar Contraction - The surgical scars may get tightened as they heal, which can cause a change in the shape of the reconstructed ear or may damage the skin around the ear.

• Damage At the Donor Site - The skin is taken from another part of the body, such as ribs or scalp, may form a scar, and in the case of the scalp, the hair might not grow back in that area.

Conclusion

Microtia is a rare condition and can be treated under the supervision of expert clinicians. The reconstructed surgeries are very safe and do not involve any complications. However, the prognosis of reconstruction depends on the skills and experience of the surgeon. Therefore surgeons should always aim to provide the perfect outcome for the patients.