February 12, 2013 — Two 2013 AHRF researchers are investigating the use of a new, highly sensitive test to discern very early stage hearing loss in patients exposed to certain chemotherapy drugs known to cause hearing loss.
The researchers, led by Sumit Dhar, PhD, Associate Professor in the Department of Communication Sciences & Disorders, Northwestern University, Evanston, Illinois, David A. Klodd, PhD, Professor of Audiology at the University of Illinois, Chicago, and Jonathan Siegel, Associate Professor in the Department of Communication Sciences & Disorders, Northwestern University, Evanston, Illinois hope that their new test will be able to significantly reduce the number of chemotherapy patients who experience hearing loss due to treatment.
The new test is actually a significant improvement on a currently-used testing technique called distortion-product otoacoustic emissions, or DPOAEs. DPOAEs deliver two tones to the ear and then measures the ‘echo’ from the interacting waves emanating from the outer hair cells of the cochlea in the inner ear. This test can assess hearing loss in a wide range of frequencies from low pitches to high pitches, but its efficacy at determining hearing loss in the high frequencies tops out at less than 6 kHz. The AHRF researchers have made dramatic improvements in the test hardware and test algorithm to enable measurement of DPOAEs up to 20 kHz.
Hearing loss in this range is usually not initially noticed, but losses in this range often lead to subsequent losses in hearing in the lower frequencies, so being able to determine hearing loss above 6 or 8 kHz, can help drive treatments and preventive measures to stop the hearing loss from “spreading” into lower frequencies, where they are much more noticeable to the patient and can negatively impact quality of life and communication. “Hearing loss in these ranges often indicates that the loss is going to start expanding through the lower frequencies where hearing loss is actually perceived as a problem. By identifying HL at these high frequencies, steps can be taken to stop its progression,” says Dr. Klodd.
The researchers are investigating the efficacy of their DPOAE test in patients undergoing chemotherapy containing the drug cisplatin, an ototoxic drug known to cause hearing loss that starts in the higher frequencies above 8 kHz. They plan to test the new DPOAE sensor in approximately 20 patients receiving cisplatin chemotherapy treatment (as well as 20 control patients not receiving cisplatin) at the University of Illinois at Chicago. “These are patients who are already undergoing extremely stressful treatment and are coping with the fact that they may have a life threatening, or at the very least, life altering diagnosis. The last thing they need is to develop hearing loss over the course of their chemo therapy, or in the months following treatment, as so often happens in these cases where the patient is sensitive to cisplatin,” says Dr. Dhar. “The goal is to detect the hearing loss before the patient does, and to begin treatment and prevention protocols so that these patients can enjoy a better quality of life once they get better.”