WHAT IS MICROTIA?
Microtia is a congenital ear deformity where the outer ear does not fully develop during the first trimester of pregnancy.
How to pronounce “Microtia”
Atresia is the absence of an ear canal. This is associated with almost all cases of microtia.
How to pronounce “Atresia”
Microtia Grades / Classification
Incidence and possible causes of Microtia
Microtia occurs in every 6,000 to 12,000 births. Microtia occurs more commonly in males and on the right side (unilateral). Approximately 10% may occur on both sides (bilateral). Microtia usually occurs as an isolated deformity although it can present itself as part of a spectrum of other deformities, either minor or major such as hemifacial microsomia, Goldenhar syndrome and Treacher-Collins syndrome. Most patients with the most severe form of microtia also lack an external auditory canal, also known as “aural atresia”.
Although causes of microtia and other ear deformities are difficult to define, some theories include a decreased blood supply to the developing ear in-utero. Others have theorized certain medication taken by the mother during pregnancy such as Accutane, Thalidomide and Retinoic Acid. Environmental factors have also been questioned.
Microtia Ultrasound During Pregnancy
Many parents ask the question “Why was the microtia missed during the ultrasound”?
It is important to understand why the ultrasound is performed in the first place. The ultrasound is performed to evaluate several things. Some of these factors are:
1) Delivery date
2) Detect ectopic pregnancies
3) Detect heart rate
4) Confirm normal anatomy, such as the heart, brain, lungs, kidneys, etc…
THE EARS ARE NOT NORMALLY THE TOP PRIORITY ON THE ULTRASOUND EVALUATION!
This is one of Dr. Bonilla's patients who underwent a 4-D ultrasound where the microtia on the right ear can be seen.
TREATMENT OPTIONS FOR MICROTIA / ATRESIA
It is best to divide the treatment of microtia & atresia into two categories: 1) External Ear Options 2) Hearing Options.
Click below to learn about all the options in detail…
Children born with bilateral microtia (both sides affected) are managed slightly differently than those with unilateral (one-sided) microtia.
Luckily, children with unilateral microtia have the other normal side to hear good, crisp, clean sounds. Children with bilateral microtia don’t have that luxury. Their hearing loss requires amplification with a bone-conduction hearing aid. There are usually three specialists involved in obtaining a bone-conduction hearing aid. The primary care doctor usually refers the child to an ear, nose and throat specialist. A hearing test is performed by an audiologist and this person is usually the one that dispenses and tests the hearing aid.
If one wants to know what a child with bilateral microtia hears, it is rather simple to reproduce this hearing loss. If one places a finger in each ear in order to totally occlude the ear canal, that is what a child with bilateral microtia and atresia hears. One may ask, then how can the child hear if both ear canals are occluded. The answer is simple: Bone Conduction. Because the vast majority of children with microtia have normal inner ears (where the hearing nerve is located), sound travels via the skull via vibrations. In other words, a sound will strike the skull, nose, jaw, etc. and a vibration gets transmitted straight to the inner ears, totally bypassing the ear canals.
Dr. Bonilla is a strong believer in using our own natural cartilage for ear reconstruction instead of a manufactured product. Our own living tissues have a much longer life, if reconstructions are done well.
The natural cartilage bends which makes it the ear much safer to trauma.
The medpor or plastic porous implant has the risk of exposure or fracture for the rest of the patient’s life.