Final Exam, Case #3 Flashcards
What are the patient’s amplification options? What are the pros and cons of each options?
The results from today’s testing were reviewed with the patient. In regards as to how to treat his unilateral deafness, the patient was educated about the different, available treatment options. Both the CROS and bone implanted devices, such as the Baha and the Ponto were discussed. It was explained that both devices route all stimuli from the poor ear to the better ear, but achieve this through different principles. The CROS system is a non-surgical option that is able to overcome the head-shadow effect by placing a microphone on the poor ear and routing the signal wirelessly to a hearing aid on the good ear. The head shadow effect is the reduction in intensity (~7 dB) of stimuli traveling from one ear to the contralateral one as a result of sound transmission through and around the skull. By overcoming this effect, the CROS system is able to improve speech understanding, but not necessarily localization (Taylor and Mueller, 2017). The patient was informed the CROS system is not always covered by insurance, but it has a trial period that would enable him to return the devices in 30 days’ time.
A bone anchored device is a surgical option that is also able to overcome the head shadow effect, but by through bone conduction. Due to this process, the device is able to stimulate the good cochlea, bypassing the outer and middle ear systems entirely. They can also be comfortable to wear, and offer a natural sound quality without occluding the ear canal. While there are many benefits to the bone implanted devices, they require surgery and can be irreversible. They also cannot solve the lack of spatial awareness and poor localization abilities, that all patients with single-sided deafness experience (Kitterick, et al., 2016).
How should output be verified for each option?
Different methods will be utilized to verify the fitting, depending on the device that the patient decides to pursue. If he selects the CROS system, Real Ear Measurements (REM) can be used to verify appropriate prescriptive targets. This verification strategy is key to ensuring that the devices are matching prescriptive targets while the patient is wearing them. These measurements are conducted with a probe microphone inserted into the patient’s ear canal and then the hearing instruments placed over the probe. For the purpose of verifying the CROS system, the probe would be inserted into the ear canal of the good ear, where the sound is being transmitted to, and the speaker would face the patient directly. This arrangement will allow the probe microphone to measure the output of the hearing aids that are picking up the stimuli from the bad ear. If the patient selects a bone implanted device, REM cannot be used as a verification measure. Rather, functional gain measures will be utilized. Functional gain is the comparison between the patient’s unaided and aided thresholds in the sound field.
How should the fitting for each option be validated?
Lastly, if the patient decides to pursue either the CROS or a bone-anchored device, the fitting will be validated through subjective outcome measures and speech in-noise testing. Subjective questionnaires, such as the Abbreviated Profile of Hearing Aid Benefit (APHAB) and the Client Oriented Scale of Improvement (COSI), can provide insight into the patient’s self-perceived disability. Both questionnaires can be administered before the fitting and then one month after the fitting. Additionally, speech-in-noise testing, with the Quick-SIN, can evaluate how the patient can understand speech in the presence of background noise (Taylor and Mueller, 2017). Results obtained in the aided condition can be compared with unaided results to objectively measure aided benefit. In regards to the bone implanted option, speech-in-noise testing can be used to predict outcomes. Research has demonstrated that the Quick-SIN can be used as a predictor as to how patients will perform with the implant. This can be done by placing the implant on a soft-band, and placing the headband on the mastoid of the deaf ear (Snapp, et al., 2010).
