PP301 - AmpCROS Eligibility and Usefulness

Abstract:
AmpCROS (Amplification + CROS- Contralateral Routing of Signal) refers to a method of fitting bilateral hearing aids to individuals with asymmetric hearing loss and speech-recognition abilities. Unfortunately, no published literature is available to demonstrate the benefits or limitations of this style of fitting. Here we present data from 27 patients who were fit with AmpCROS fitting. We discuss their audiogram characteristics, and the subjective benefit and shortcomings they report for use/disuse of this setting. This information will help audiologists determine candidacy for this setting, as well as provide evidence of patient feedback with these settings.

Summary:

Introduction:
AmpCROS (Amplification + CROS- Contralateral Routing of Signal) is a technique of fitting asymmetrical hearing losses. In this approach, amplification is provided to both ears, while also routing signals from the poorer ear to the better ear. An ideal candidate for an AmpCROS style fitting is thought to be someone with an asymmetric hearing loss and reduced speech recognition abilities in the poorer ear. However, to date, there are no studies detailing the candidacy criteria, nor do any detail the benefits or limitations of these devices from the patient perspective. The aim of our current study is to analyze the retrospective data from a large medical system to determine the audiometric findings and subjective benefits/limitations of AmpCROS style fittings. These findings can provide audiologists with evidence of the type of audiograms for which AmpCROS approach can be used, and common benefits or complaints reported by patients.

Method:
We conducted a retrospective chart review and identified 27 patients from the Stanford Ear Institute who were fit with AmpCROS devices. We provide descriptions of their hearing loss in the poorer and better ears, their speech recognition scores, and their subjective feedback from the AmpCROS style fitting.

Results:
The average PTA of the better ear and poorer ear pure tone average is 25.8 dBHL (SD = 20.3, Range = 5-68 dBHL) and 71 dBHL (SD = 20.3, Range = 33 to 120 dBHL) respectively. The better ear and poorer ear word recognition scores were 87.6% (SD = 17, Range = 28 to 100%) and 18% (SD = 20.5, Range = 0 to 70%) respectively. No post-fitting aided tests of speech recognition were available to compare performance for CROS vs AmpCROS mode. However, analyses of the clinic notes across participants show a divide in preferences for both using and not using this mode of amplification. Overall, 17 participants chose to continue the use of AmpCROS mode, while 10 participants decided to either switch to CROS amplification or use bilateral amplification. Qualitative analyses of the data indicated some themes for their preferences. Some of the reasons participants reported for continued use of AmpCROS include preventing auditory deprivation, better sound awareness on the poorer ear side, better speech understanding, tinnitus suppression, and music sounding fuller with the AmpCROS mode. Some of the reasons patients decided to switch from the AmpCROS mode are that the AmpCROS setting was overwhelming or too loud, caused sound distortion, was noisy, led to poor speech understanding, or resulted in no reported difference between CROS and AmpCROS mode.

Conclusion:
Though post-fitting aided tests of speech recognition are not available, the pre-fitting information and patient reports will provide clinical audiologists with evidence of the different types of hearing loss configurations where AmpCROS setting has been used and the reasons why this setting is commonly liked or disliked. Given that most patients continued to use AmpCROS styles of fitting, and the ability to avoid long-term auditory deprivation in the poorer ear that can hinder cochlear implant outcomes, audiologists should continue to try this approach in cases of asymmetrical hearing losses.