What is Pediatric Microtia?
Microtia is when a baby is born with a smaller ear than normal. The ear is usually so abnormally shaped and small that it no longer looks like an ear, and it is occasionally completely absent (anotia). In the majority of children this occurs on only one side, where the other ear is of normal dimensions. There are several grading systems used to describe how severe the microtia is.
What are the different types of Pediatric Microtia?
The mildest form of microtia is when the ear appears smaller than usual but still has most of the features that a normal ear has. The most common scenario is one where the cartilage part of the ear is very small and abnormally shaped and the ear lobe is present, but rotated forward and upward giving it an abnormal appearance. In this most common scenario, the ear canal is also absent or very narrowed. When the ear canal is absent it is called aural atresia. If aural atresia is present the child should be evaluated by an Ears, Nose and Throat (ENT) specialist to determine what the effects on hearing are and what if anything should be done to improve hearing.
It is important to note that microtia is most often associated with a process called craniofacial microsomia which is also called hemifacial microsomia. This condition is present when there are abnormally small features present on one or both sides of the face. Craniofacial microsomia is believed to be due to an abnormal circulation of blood to the face during development which leads to decreased growth of the skin, fat and bone of the face and often microtia.
More rare conditions are also associated with microtia. These include Goldenhar syndrome and Treacher Collins syndrome. These patients can have multiple issues in addition to craniofacial microsomia and microtia and should be treated in a special way for these reasons.
How is Pediatric Microtia treated?
The external ear is mostly made up of skin and cartilage. This cartilage is fairly unique in the body. It bends very easily and returns to its exact shape. This special property helps the external ear avoid injury. The ear canal leads to the eardrum which transmits sounds to the inner ear that allows us to hear. It is possible to have a normal appearing external ear and not have a canal, and also possible to be missing the external ear and have an open canal and normal hearing. However, most often people with microtia have some abnormality of the canal and possibly the inner ear.
There are three main approaches to reconstruction of the external ear for treatment of microtia. The two most popular methods involve burying a framework under the skin to create a new ear which will be a permanent part of the patient. The first method uses an implant called Medpor to create a normal appearing ear. The second, which is the oldest type of reconstruction, uses rib cartilage, harvested from the chest that is carved and assembled into a framework with a shape similar to the Medpor framework. The third method which is not part of the patient, is to use a prosthetic ear that is anchored to implants in the bone. This prosthesis can be removed.
Rib Cartilage Ear Reconstruction
This approach is the oldest and most widely performed technique for ear reconstruction. It has been used for over 50 years. This approach is usually performed at 8-10 years of age. The general idea is to harvest the strong cartilage from the rib cage, carve this cartilage and assemble it into a framework using wires or suture material. The framework is placed under a skin pocket in the location of the microtia to create a new external ear.
This approach uses the child’s own tissue (cartilage) to create the new ear which is appealing to many patients. The cartilage is strong and resistant to breaking. There are a couple of downsides to this approach. To harvest the cartilage an incision must be made in the chest and the removal of cartilage from several ribs is needed. This can cause an irregular shape to the chest on the side of surgery. In order to get enough cartilage to make an ear of normal size, we must wait until the child is about age 8-10, an age when teasing from peers and self-esteem issues are often already present.
There is not enough skin in the location of the microtia to allow for the ear framework to be covered on its front and back sides at the same time. Therefore, the framework is put under the skin and lies flat against the head. This must be allowed to heal for a period of time to allow the skin to become adherent to the cartilage. The ear is then elevated to try to project the ear forward sufficiently to match the normal side. Other components of the ear reconstruction are also performed in stages. The rib cartilage approach usually takes 3-4 surgeries with the classic approaches.
We do not favor this approach for most patients. Our primary concerns are related to deformity and pain in the chest donor site, the number of surgeries required and the quality of the average result. While some surgeons, with many years of experience, can provide reliable results with the rib cartilage approach, the results can be quite variable. We believe that the goals of ear reconstruction should be to have the average result obtained look like an ear. In our experience the average result of an ear reconstruction from rib cartilage does not look like a normal ear and still draws unwanted attention.
Perhaps the most significant issue with the rib cartilage approach is that it is usually performed at an average age of 8-10 years of age. By this age children will already have significant self esteem issues and problems with teasing by peers. Unfortunately, we fear that much of the teasing and self-esteem issues that we are trying to avoid with the ear reconstruction will already be present by age 8-10.
Medpor Ear Reconstruction
The concept of the Medpor approach is similar to that of rib cartilage. We are placing a scaffold under the skin to create a contour that looks like a normal ear. This approach relies on a Medpor implant (porous polyethylene) to provide the shape and projection of the ear. The pore structure of the Medpor allows for growth of the patient’s tissue into the implant. Using the Medpor implant removes the need for surgery in the chest to harvest of cartilage. Thus there is no pain, scarring or deformity of the chest with this approach.
The Medpor implant is made up of two pieces that are custom assembled to provide the new ear with a similar size and shape and details of a normal ear. The pores of the Medpor implant allow the patient’s tissues to grow into the implant. While it is not living tissue, this tissue ingrowth helps provide resilience to infection. The implant is covered with a thin layer of tissue from the scalp and skin from the ears. This thin tissue allows for the delicate features of the ear to be created. The skin covering the back of the ear is harvest from the groin crease which leaves a scar that is hidden in the under wear line. In our experience, the average ear reconstruction from the Medpor approach looks like an ear and alleviates unwanted attention.
There are several advantages of the Medpor approach when compared to the rib cartilage reconstruction. There is no scarring, pain or chest deformity associated with the harvest of the rib cartilage. The Medpor technique can be done at a much earlier age, because we don’t have to wait for the rib cartilage to grow. We usually perform this approach from age 4-5 years and up. This means that the whole reconstruction process can be completed before any issues with self-esteem or teasing arise. The use of the tissue from the scalp and small skin grafts to completely cover the ear at the first surgery also means that the Medpor reconstruction can be completed in fewer surgeries than the average rib cartilage approach. Usually there is a well projected ear with normal positioning of the earlobe after one surgery.
The Medpor approach can easily be integrated with an atresia reconstruction or BAHA placement to improve hearing. Careful coordination between the Ears, Nose and Throat surgeon and plastic surgeon is needed to make sure that the best possible result in both hearing and the appearance of the ear is achieved.