October 9, 2012 Audiology

Audiology in Brief: October 9, 2012

Device Aids Screening of Cancer Treatment-Related Hearing Loss

A new device may help patients avoid the hearing loss associated with some cancer treatments. These treatments can damage hearing, typically first in basal regions of the cochlea specific for high-frequency hearing, and then in more apical regions relevant to speech understanding. Monitoring of high-frequency hearing loss, therefore, can be an effective early indicator of ototoxicity, and could lead the oncology medical team to adjust the drug dosage or switch to less ototoxic medications.

Telehealth technology—in which patients use a device that alerts health care professionals to a change in hearing—may improve access to ototoxicity monitoring. Researchers designed a portable high-frequency audiometer that can reliably detect a person's drug-related hearing changes relative to pre-treatment using an automated test. The system includes a wireless cellular modem capable of notifying a remote health care professional if the patient has a significant change in hearing. The study evaluated the system on participants in a sound-proof booth, a noisy hospital ward, and their homes. Results indicate that patients can use the system effectively to monitor hearing changes remotely in their homes or in a hospital ward, ultimately enabling early detection of ototoxicity and potentially avoiding hearing loss. Search doi: 10.1109/TBME.2012.2204881.

Auditory Cortex 'Feels' Touch

People who are born deaf use the auditory cortex to process touch and visual stimuli to a much greater degree than do hearing people. The finding, published in the Journal of Neuroscience, reveals how the early loss of a sense—in this case, hearing—affects brain development.

The researchers used an already-known perceptual illusion in people with normal hearing—known as the auditory-induced double flash—in which a single flash of light paired with two or more brief auditory events is perceived as multiple flashes of light. They used a tactile stimulus—a double puff of air—instead of the auditory stimulus, but kept the single flash of light. Participants were exposed to tactile stimuli and light stimuli separately and to time periods without stimuli to establish a baseline for brain activity, measured using magnetic resonance imaging.

People with normal hearing exposed to two puffs of air and one flash of light saw only a single flash. But when exposed to the same mix of stimuli, participants who are deaf saw two flashes. The scientists observed much greater activity in Heschl's gyrus—the temporal lobe site of the primary auditory cortex—although not all brains of people who are deaf responded to the same degree. Those who are deaf and had the highest levels of activity in the primary auditory cortex in response to touch also had the strongest response to the illusion.

The finding may be useful in several ways. For example, if touch and vision interact more in the people who are deaf, touch could be used to help students who are deaf learn math or reading. The finding also has the potential to help clinicians improve the quality of hearing after cochlear implants, especially among children born deaf who are implanted after the ages of 3 or 4. The ability to measure how much the auditory cortex has been taken over by other sensory processing could offer insights into the kinds of intervention programs that would help the brain retrain and devote more capacity to auditory processing.


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