Monitoring carboplatin ototoxicity with distortion-product otoacoustic emissions in children with retinoblastoma.
OBJECTIVE
Carboplatin is a common chemotherapy agent with potential ototoxic side effects that is used to treat a variety of pediatric cancers, including retinoblastoma. Retinoblastoma is a malignant tumor of the retina that is usually diagnosed in young children. Distortion-product otoacoustic emission tests offer an effective method of monitoring for ototoxicity in young children. This study was designed to compare measurements of distortion-product otoacoustic emissions obtained before and after several courses of carboplatin chemotherapy in order to examine if (a) mean distortion-product otoacoustic emission levels were significantly different; and (b) if criterion reductions in distortion-product otoacoustic emission levels were observed in individual children.


METHODS
A prospective repeated measures study. Ten children with a median age of 7.6 months (range, 3-72 months) diagnosed with unilateral or bilateral retinoblastoma were examined. Distortion-product otoacoustic emissions were acquired from both ears of the children with 65/55 dB SPL primary tones (f(2)=793-7996 Hz) and a frequency resolution of 3 points/octave. Distortion-product otoacoustic emission levels in dB SPL were measured before chemotherapy treatment (baseline measurement) and after 3-4 courses of chemotherapy (interim measurement). Comparisons were made between baseline and interim distortion-product otoacoustic emission levels (collapsed across ears). Evidence of ototoxicity was based on criterion reductions (≥ 6 dB) in distortion-product otoacoustic emission levels.


RESULTS
Significant differences between baseline and interim mean distortion-product otoacoustic emission levels were only observed at f(2) = 7996 Hz. Four children exhibited criterion reductions in distortion-product otoacoustic emission levels.


CONCLUSIONS
Mean distortion-product otoacoustic emission levels at most frequencies were not changed following 3-4 courses of carboplatin chemotherapy in children with retinoblastoma. However, on an individual basis, children receiving higher doses of carboplatin exhibited criterion reductions in distortion-product otoacoustic emission level at several frequencies. These findings suggest that higher doses of carboplatin affect outer hair cell function, and distortion-product otoacoustic emission tests can provide useful information when monitoring children at risk of developing carboplatin ototoxicity.
Bhagat
Shaum P
SP
School of Audiology and Speech-Language Pathology, The University of Memphis, Memphis, TN, United States. sbhagat@memphis.edu
Bass
Johnnie K
JK
White
Stephanie T
ST
Qaddoumi
Ibrahim
I
Wilson
Matthew W
MW
Wu
Jianrong
J
Rodriguez-Galindo
Carlos
C
D000970:Antineoplastic Agents / Q000009:adverse effects*; D001299:Audiometry / Q000379:methods; D016190:Carboplatin / Q000009:adverse effects*; D002648:Child; D002675:Child, Preschool; D005260:Female; D034381:Hearing Loss / Q000139:chemically induced* / Q000175:diagnosis*; D006801:Humans; D008297:Male; D017084:Otoacoustic Emissions, Spontaneous / Q000187:drug effects; D010865:Pilot Projects; D011237:Predictive Value of Tests; D019572:Retinal Neoplasms / Q000188:drug therapy*; D012175:Retinoblastoma / Q000188:drug therapy*
D000970:Antineoplastic Agents; D016190:Carboplatin