A prospective study on radiation-induced changes in hearing function.
OBJECTIVE
To quantitate changes in hearing function after radiotherapy for head-and-neck tumors.


METHODS
At the Department of Radiotherapy and Radiation Oncology, 32 patients were irradiated for head-and-neck tumors. Three-dimensional treatment planning was applied. Total tumor doses were 30.0-77.6 Gy, local doses to the inner ear (n = 64) ranged from 1.7 to 64.3 Gy. Audiometry was performed before the onset of radiotherapy (RT), at a tumor dose of 40 Gy or at the end of palliative treatment, at the end of curative RT, and 2-6 months post-RT. Assays applied were frequency-specific threshold measurements for air and bone conduction, measurements according to Weber and Rinne, tympanometry and assessment of the stapedius reflex.


RESULTS
Age and prior disease significantly decreased, whereas previous or concurrent alcohol consumption significantly increased hearing ability. A significant reduction in hearing ability during RT was found for high frequencies (at 40 Gy) and low frequencies (at end of RT), which persisted after RT. No differences were observed for air or bone conduction. None of the other assays displayed time- or dose-dependent changes. Dose-effect analyses revealed an ED50 (dose at which a 50% incidence is expected) for significant changes in hearing thresholds (15 dB) in the range of 20-25 Gy, with large confidence limits.


CONCLUSIONS
Radiation effects on hearing ability were confined to threshold audiogram values, which started during the treatment without reversibility during 6 months postradiotherapy.
Herrmann
Franziska
F
Department of Oto-Rhino-Laryngology, University of Technology-Dresden, Dresden, Germany.
Dörr
Wolfgang
W
Müller
Rainer
R
Herrmann
Thomas
T
D000328:Adult; D000368:Aged; D001299:Audiometry; D004307:Dose-Response Relationship, Radiation; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006309:Hearing / Q000528:radiation effects*; D006801:Humans; D008875:Middle Aged; D015999:Multivariate Analysis; D011446:Prospective Studies; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal