Are people with single sided deafness candidates for bone anchored hearing systems?
Yes. There are two main bone anchored hearing system (BAHS) candidacy indication categories, and one secondary indication category. Audiologically speaking, patients can be fitted with a Ponto system if they have conductive and mixed hearing losses, or if they have a unilateral profound hearing loss, also known as single-sided deafness (SSD). The secondary indication category includes patients who have other physical characteristics or other medical conditions that make wearing a conventional hearing aid impossible.
Patients with SSD have one completely nonfunctioning cochlea and one functioning cochlea. When looking at their audiogram, you'll see two very different threshold measurements: one showing normal or near-normal hearing, the other showing a profound sensorineural hearing loss.
A patient qualifies as a BAHS SSD candidate if their better ear has normal or near-normal hearing (with an average air conduction threshold of < 20 dB HL), and the worse ear has a profound hearing loss. They can also be candidate for BAHS treatment if they cannot have a CROS aid, (e.g., have an allergic reaction to an earmold), or if they are a candidate for a CROS aid, but choose not to use an air conduction CROS system. For patients with SSD, the sound processor is placed on the deaf side, and picks up sound that is then transferred to the functioning cochlea on the opposite side via bone conduction, working as a CROS device.
Candidates for a BAHS include individuals with SSD caused by:
- Acoustic neuroma
- Sudden deafness
- Congenital causes
- Ototoxic drugs
- Meniere's disease
This Ask the Expert is an excerpt from the CE Course, Bone Anchored Hearing Systems - Principles and Candidacy.