Treatment Options for Aural Atresia
1. Bone Conduction Auditory Processors
Bone conduction devices are a durable treatment option to correct hearing loss in patients with unilateral or bilateral atresia. These devices are commonly referred to by the acronym BAHA, which stands for “bone anchored hearing aid.” The BAHA is anchored on babies and young children with a soft headband, and can be surgically implanted in children once they reach 5 years of age. Surgery involves placement of a titanium abutment or magnetic plate into the skull. Once healed, an external sound processor is connected to the abutment or magnetic plate. The sound processor vibrates the skull to directly stimulate the inner ear (auditory) nerve. This allows children with aural atresia to hear, as it bypasses the anatomic abnormalities of the outer and middle ear.
I have recently developed a scarless technique for placing the titanium implant for the Bone Anchored Auditory Processors during the 1st stage Medpor ear reconstruction surgery. Currently, this technique can be performed with both the Cochlear Baha (including the Attract magnet under the skin) and the Oticon Medical Ponto products. This provides my Microtia and Atresia patients the ability to hear directly through bone conduction and is an excellent alternative to those that cannot have or choose not to have atresia repair.
Three companies currently manufacture bone conduction auditory processors:
All three devices can be implanted into the skull or worn on a soft headband. The abutments for the Cochlear and Oticon models protrude slightly out from the scalp for attachment to the processor, while the Sophono model uses an embedded magnetic plate flush to the skull that is coupled to the plate of the sound processor.
A newborn baby can wear the softband BAHA, but the surgery to implant the Bone Conduction Auditory Processor should not be performed BEFORE the Medpor ear surgery.
2. Atresia Repair surgery (Canalplasty)
Atresia Repair is a complex surgical procedure to restore hearing in children with unilateral or bilateral atresia. The objective of atresia repair is to create a healthy skin-lined ear canal with an eardrum (tympanic membrane) and middle ear bones (ossicles) that will allow sound waves to be conducted to the inner ear. Approximately 50% of children born with isolated microtia are candidates for canalplasty. However, this percentage is lower in children with associated conditions such as “Treacher Collins Syndrome” or Hemifacial Microsomia.
Candidates for canalplasty must have the following:
- A functioning cochlea, the part of the inner ear which converts sound vibrations into nerve impulses sent to the brain (determined by audiogram)
- Adequate development of the middle ear space to allow the ear bones to vibrate
- Favorable facial nerve anatomy
An audiogram plus a high resolution CT scan will determine if your child is a good candidate for atresia repair. The scan is evaluated using a series of parameters based on the anatomy of the ear. The Jahrsdoerfer scale is most commonly used to score the CT. Using a scale between 1 and 10, if your child’s CT scan scores a 7, 8, or 9 out of 10, your child is predicted to have a 70%, 80% or 90% chance of achieving normal or near normal hearing, respectively, after atresia repair surgery. Children with scores of 6 and below are generally not recommended for atresia repair surgery. The CT scan can be done once your child is at least three years of age to allow sufficient development of the middle ear bone structures.
It is important to understand that with the Medpor technique of surgery, the atresia repair is done FIRST, but with the Rib Cartilage technique, the atresia repair is done AFTER the ear reconstruction.