By Terry Zwolan, Ph.D.
Over the past 3 years, the Institute for Cochlear Implant Training (ICIT) Advanced Surgeons’ Training Course has provided in-depth education for over 60 CI surgeons from the US and around the world, which could improve outcomes of thousands of CI recipients. Similar training and education needs to exist for audiologists. This blog describes some of the areas that are covered in the Advanced Audiology CI Course (AAC), which was developed by ICIT to meet this educational need.
It is the responsibility of the cochlear implant (CI) team, which typically includes the implant surgeon, audiologist, and speech-language pathologist, as well as other professionals, to determine who is an appropriate candidate to receive a CI. It is also their responsibility to ensure the device is adequately placed, appropriately programmed, and to monitor device function to ensure the patient is receiving optimal benefit from its use. In recent years, the responsibilities of CI audiologists have expanded considerably and become increasingly complex as technological advances with external and internal devices have accelerated at fast rates.
Early on, many CI teams declined to implant patients with cochlear anomalies such as cochlear malformations or ossification. Today, it is estimated that approximately 20-30% of children who receive a CI have some type of cochlear abnormality.1 This increase in access is the result of several factors, including improvements in preoperative radiographic and electrophysiologic tests2, technological advances in internal devices (such as split and compressed arrays), and improved surgical device placement. This makes it necessary for audiologists to understand the anatomy and physiology of the ear, particularly as it relates to hearing and electrical current. For example, a patient with an ossified cochlea may receive a split electrode array. The audiologist must understand the reason for choosing such a device and be able to counsel the patient regarding expected outcomes. Mapping the device necessitates understanding the physiology of both the normal and abnormal inner ear in order to manage the flow of current that will be delivered to the electrodes located in various areas of the cochlea. This includes a basic understanding of mapping parameters that can be changed or tried when difficult situations, such as stimulation of the facial nerve, occur.
Over the years, advances in speech processing have resulted in great increases in speech recognition scores obtained by CI recipients. In early trials, adults with CIs obtained scores of approximately 15% on CNC Monosyllabic Words and approximately 35% on simple CID Sentences.3 More recently, these scores have increased to approximately 58% for CNC Words and over 80% for the more challenging AzBio Sentences.4 In order to optimize performance and have their patients attain such scores, CI audiologists need to have a basic understanding of sound processing strategies, as well as understand the parameters that can be manipulated or changed to optimize the patient’s ability to hear with the device. Mapping a CI comes with great responsibility; provision of an inappropriate map can result in months or years of less than optimal hearing and may lead to greatly reduced outcomes for both children and adults. Conversely, provision of an optimized map can lead to life-changing results.