Treatment of congenital microtia

Neonatal deformity is a major topic that has attracted the attention of the whole society. It refers to the situation where a newborn baby has a deformity in a part of the body due to certain factors, which makes people feel very pitiful. Among them, congenital microtia is the most common disease. So, what is congenital microtia? How to treat congenital microtia? Now let’s go and learn more about it.

Microtia is what we usually call underdeveloped auricle. In mild cases, only the auricle is smaller than normal, while in severe cases, the entire auricle may be absent, often accompanied by external auditory canal atresia and middle ear hypoplasia, but the inner ear development is mostly normal. Studies have shown that microtia is related to viral infection in early pregnancy, medication, mental stimulation, or exposure to radiation and environmental pollution. The above factors affect the development of the first and second branchial arches of the fetus, resulting in congenital microtia. According to the survey: the incidence rate of this disease in our country is as high as about 4000:1. It should be noted that microtia is not hereditary. According to incomplete statistics, the family incidence rate in my country is 2.5%, which means that 2.5 out of 100 families have such patients.

Congenital microtia (Microtia), also known as congenital external and middle ear malformation, is characterized by severe hypoplasia of the auricle, atresia or stenosis of the external auditory canal, and middle ear malformation, while the inner ear development is mostly normal and there is a certain hearing ability through bone conduction. Treatment requires total auricle reconstruction and hearing function reconstruction surgery.

Clinical manifestations

The clinical features of patients with congenital microtia mainly involve the auricle, external auditory canal and middle ear, while the inner ear is often not affected. According to the degree of deformity, the most commonly used clinical classification is three types:

Grade I: The size and shape of the auricle change, but the important surface landmarks of the auricle remain, the external auditory canal is narrow, and in severe cases, the external auditory canal is closed;

Grade II: The most typical, with only the vertically positioned helix, sausage-shaped, and the external auditory canal closed;

Grade III: Only a mass of skin and cartilage remains. In severe cases, the ear is missing.

Disease treatment

The treatment of congenital microtia mainly includes two aspects: one is the reconstruction of the external ear, and the other is the reconstruction of hearing function. Generally, the external ear is reconstructed first, followed by the restoration of hearing function. Hearing reconstruction surgery often damages the skin behind the ear and must be performed after auricular reconstruction.

External ear reconstruction

The normal auricle is composed of a thin skin soft tissue wrapped around an elastic cartilage scaffold. It has an elastic thin shell structure and is composed of the helix, antihelix, tragus, antitragus, earlobe, concha, triangular fossa, and navicular fossa. It is convex, concave, and convoluted with a complex shape. Therefore, auricle reconstruction is a difficult and complicated operation. Although it is currently possible to create a reconstructed ear that is very similar to the normal auricle, there are many factors that affect the shape of the reconstructed ear. The tightness, thickness, and size of the residual ear and the skin behind the residual ear, and the length, shape, and thickness of the rib cartilage used all vary greatly. These conditions will affect the results of the operation. The scar constitution of some individual patients will also affect the appearance of the reconstructed ear. Therefore, patients who request auricle reconstruction, understand the difficulties of the operation, and are realistic about the results can undergo auricle reconstruction surgery; otherwise, they should be cautious. The elderly and infirm should wear prosthetic ears instead of undergoing ear reconstruction surgery.

1. Timing of surgery

The timing of ear reconstruction surgery is very important and is one of the main determining factors in achieving ideal surgical results. We believe that considering the development of costal cartilage, auricle and psychological factors, 9, 10 and 11 years old are the best ages for ear reconstruction. If the patient is too young, his or her own costal cartilage will be small, thin and soft, which will affect the preparation of the auricular cartilage scaffold and thus the final surgical result. In addition, premature surgery will require the removal of more costal cartilage. The chance and degree of chest deformation will be higher and more severe if one more weight-bearing costal cartilage is removed than if one less cartilage is removed at an older age. However, it is best to complete the external ear reconstruction surgery before puberty, because the psychological changes of adolescent children are great, and completing it before puberty will have much less impact on the child's psychological development. Although we have solved the ear reconstruction technology for elderly patients, it is best not to wait until you are too old to have surgery. With age, the texture of the rib cartilage will change and may even turn yellow and brittle, increasing the difficulty of making the ear cartilage scaffold.

2. Reengineering method

Ear reconstruction usually requires 2 to 3 surgeries. There are two specific methods.

One is called the Brent method. Brent was an American doctor. Later, Japanese doctor Nagata made major technical improvements. This method is the most widely used and popular method worldwide. This method does not require skin expansion. This method generally requires two operations. The first operation involves harvesting rib cartilage and directly implanting an ear frame carved from the rib cartilage under the skin behind the ear. This is the most critical part of the ear reconstruction surgery. The second surgery was to erect the ears. If you do it a third time, it will be more beautiful. Each operation takes about 10 days, with 4-6 months between each operation. This method can produce thin ears with clear contours and small surgical scars. It is also simple, safe, short in each treatment, and causes little pain to the patient. This method is suitable for patients with abundant skin on the deformed ears, loose skin behind the deformed ears, and a large area, and we prefer this method for patients with such conditions. One is the skin expansion method, which usually requires three operations. During the first operation, a 50-80ml water bag (i.e. skin and soft tissue expander) was implanted in the mastoid area behind the residual ear, and the hospital stay was about 4 days. Start injecting saline solution 7 days after the operation, and inject every other day. It takes about 1 month to fill up with 50-80ml of saline solution. After the injection is completed, rest for 1 month before coming back to the hospital for the second operation. During the second operation, the expander is removed, and autologous rib cartilage is cut to carve an ear frame according to the size of the healthy ear for auricle reconstruction. The hospitalization time is about 10 days. Some patients can further trim the reconstructed ear 3 to 6 months after the second operation, and the hospitalization time is about 7-10 days. Although this method takes a long time to treat and causes relatively more pain to the patient, it is the best method of skin expansion for patients with small and thick skin behind the ears.

The key to choosing the ear reconstruction method is the patient's own condition. The method that suits the patient is the one that can achieve the best results.

Hearing reconstruction

Most patients with congenital microtia have atresia of the external auditory canal. When parents take their children to see a doctor, they are often most concerned about hearing. They believe that their child is completely deaf in the affected ear, or that hearing can be completely restored by simply making a hole in the skin. In this regard, doctors need to explain hearing problems from the perspective of embryonic development of the ear and correct their misconceptions.

During embryonic development, the middle ear and external ear are mainly derived from the first and second branchial arch tissues. At 5 weeks of embryogenesis, the auricle appears as 6 hillocks on the two branchial arches, while the inner ear appears at 3 weeks of embryogenesis and originates from ectoderm tissue. Due to the different tissue sources, patients with microtia mainly have developmental deformities of the external ear and middle ear, and the inner ear is often not affected. There are two pathways for sound to reach the human inner ear. The pathway from the outer ear to the middle ear and then to the inner ear is called air conduction. Microtia causes air conduction disorder. The transmission of sound vibrations through the skull to the inner ear is called bone conduction. Microtia patients have bone conduction and are able to hear loud sounds.

Generally speaking, the affected side of unilateral microtia has about 40% hearing loss, and the hearing on the healthy side is normal. Except for a slightly poor judgment of direction, it does not have much impact on language pronunciation and daily life. Therefore, there has always been controversy over whether such patients should undergo external auditory canal shaping to improve hearing. The main reasons for opposition are that the surgery has many complications, the degree of improvement in hearing is minimal and often not lasting. In recent years, with the advancement of technology, otolaryngologists tend to prefer surgery. There are also differences between otolaryngologists and plastic surgeons on the order of operations. The lack of elasticity of the reconstructed ear will affect the otolaryngologist's surgical operation, but scars often form on the skin of the mastoid area after external auditory canal surgery, which affects the plastic surgeon's full use of the skin there for auricle reconstruction. However, as long as the position of the reconstructed ear is well reserved, experienced otolaryngologists can also perform hearing reconstruction surgery after the auricle reconstruction surgery.

Hearing surgery requires that the mastoid air cells develop so that there is enough space to form the external auditory canal. When the mastoid air cells are underdeveloped, the formation of the external auditory canal is difficult because the temporomandibular joint in front cannot be changed, the tympanic cavity above is very low, the sigmoid sinus behind is moved forward, and the facial nerve is below. Under normal circumstances, there is almost no passage from the external auditory canal to the middle ear cavity formed in the mastoid process. Therefore, those with underdeveloped air cells are not suitable for canaloplasty. On the other hand, for those with well-developed air cells, although external auditory canaloplasty can be performed to improve hearing, the author believes that the autologous fascia used to reconstruct the tympanic membrane is not a tissue transplant, but only a biological dressing to help healing. Complex situations such as infection and fluid discharge are prone to occur after the operation. The external auditory canal is formed by removing part of the mastoid bone and air cells, and patients are prone to fistula formation after tympanoplasty. In the early postoperative period, the transplanted skin graft grows well on the bone surface and the surface of the ear canal gradually becomes flat and smooth. However, as the skin graft shrinks, the mucosa of the middle ear cavity or the remaining mastoid air cells will grow into the ear canal. Exposure of the mucosa to the air will cause chronic and persistent secretions, stimulating the surrounding tissues and causing chronic inflammation. Whenever the patient catches a cold, purulent fluid will be produced. Once this happens, it is very difficult to deal with.

Under normal physiological conditions, the fluid in the mastoid air cells is discharged outward through the Eustachian tube. Surgical interference changes this normal flow direction, and the formation of a fistula causes it to flow back into the ear canal. Therefore, such surgery is non-physiological in a sense, turning a dry ear into a wet ear. The method to prevent this complication is: the external auditory canal should be made as wide as possible, close to the cavity formed during radical mastoidectomy, and during the operation, attention should be paid to keeping the middle ear mucosa intact to maintain the mastoid-Eustachian tube drainage system unaffected, and the ear canal wall should be covered with skin flaps as much as possible. However, it is quite difficult to achieve all of these goals. An ear canal that is too wide not only looks ugly, but also affects the reconstruction of the auricle. Therefore, although restoring hearing is attractive to patients, patients with unilateral microtia and normal hearing on the unaffected side must weigh the possible infection and discharge after surgery, the trouble of frequently cleaning dandruff in the reconstructed ear canal, and the restrictions on certain sports such as swimming. Whether it is worthwhile to simultaneously perform middle ear surgery, which currently does not improve hearing very well, should be carefully considered.

In short, for patients with bilateral microtia and external auditory canal atresia, external auditory canal plasty surgery to improve hearing can be considered. However, for patients with unilateral microtia, my experience is to perform partial external auditory canal reconstruction with a depth of about 1 cm, without entering the middle ear cavity, and try to cover it with a local skin flap turned inward. The operation basically does not change the flow direction of the mastoid-Eustachian tube, so there are no complications such as infection and discharge after the operation. Although the patient's hearing is not improved, he can get a certain psychological satisfaction because there is an "ear canal" structure behind the tragus, and it can also make the appearance of the reconstructed ear more complete.

Congenital microtia is a huge harm to a newborn baby and will seriously affect the baby's healthy growth. As people age, if the disease has not been effectively treated, it will not only cause physical harm to the patient but also psychological harm. Therefore, congenital microtia needs to be treated effectively as early as possible.