Ear Reconstruction and Microtia
Microtia is a spectrum of ear deformity that ranges from a “small ear” to a complete absence of the external ear. Very early in the fetus’s life the face begins to form from a series of gestational growth centers. During this time it is speculated that there is an acute event that results in the lack of growth of the ear and potentially other parts of the face. The severity of the resulting deformity is dependent on when this event occurs.
The incidence of microtia is thought to occur in approximately 1:7000 to 1:8000 births. The right side is affected approximately twice as often as the left, and bilateral deformities occur in 10% of cases. The male:female ratio is variously reported as 2:1
Grade 1 – all anatomic units are present but may be small or partially misshapen
Grade 2 – Some or most of the anatomic units are deficient or absent
Grade 3 – The ear is absent or near absent (lobular pattern microtia)
On occation the external ear deformity that is present may be part of a syndrome called hemifacial microsomia. For the same reasons that the ear failed to form normally, other portions of the face also fail to form. Specifically there are deficiencies in the maxilla, mandible, facial soft tissues, eye and the nerves that move the face. There is a large spectrum of presentation but an understanding of the potential for these associated problems in essential.
- Like all congenital facial deformity a though exam by a trained craniofacial surgeon is the first and most important early step.
- Hearing evaluation – the external auditory canal and the middle ear structures are often affected or absent. Therefore all patient with a congenital ear deformity should receive a formal hearing evaluation early in life. This may be followed by specific exams such as a CT scan to assess the inner ear anatomy as well as an ABI which will measure the degree of sensorineural or conductive hearing loss.
- Comprehensive evaluation by Oralmaxillofacial Surgeon, Ophthomologist, Genetist, and Pediatrician round out the remained or exam to rule out related issues.
Options for Reconstruction:
The ear reaches 85% of adult size by age 6 and 95% by age 8. Therefore most reconstructive efforts are performed at this time. There are three accepted forms of microtia reconstruction. Each techniques has its advantages and disadvantages but like most things it is highly dependent on the person performing the surgery and their respective experience in this type of surgery.
Autologous Rib Cartilage Reconstruction is the most commonly used technique utilized by craniofacial surgeons. This technique uses portions of the child’s ribs to create the ear framework. This is followed by 2 to 3 additional procedures where the ear construct is elevated and the earlobe is rotated into its appropriate position.
Medpore Implant with TPF Flap is a technique where a preformed implant is utilized and covered with tissue beneath the scalp. This technique negated the need for harvesting the child’s own tissue and offers the potential for a sharper and anatomically correct reconstruction. In addition, this technique is a single stage operation and often does not require any additional surgeries. The major disadvantages of this operation are that it has a higher rate of implant infection, exposure and extrusion as well as eliminates the option of rib graft reconstruction.
Ear Prosthesis reconstruction is an excellent option when the first two options have failed or as a first modility in a person that presents later in life. With this technique a metal post is surgically placed in the auricular bone. A replica of the normal ear is made out of a prosthetic material and attached to the metal post. The major advantage of this technique is that is the most aesthetically normal option and does not have the surgical morbidity. The disadvantages are that it is less durable and will need to be replaced or repaired at some point in time. Also, as this implant is removable there is a fair degree of potential for loss and damage in the active life of a child.