Effects of X-ray Irradiation on Hearing in Guinea Pigs

Abstract

Effects of X-ray irradiation on the hearing with CM and ABR to both air- and bone-conduction stimuli were studied continuously from immediately after the irradiation to a few weeks later. At 2, 4, and 6 krad, only slight conductive hearing impairment was found, but at 8 krad or more, CM and ABR disappeared abruptly, after having increased briefly. Advanced sensorineural hearing loss appeared at about 10 hours after irradiation ended at 8 krad, at about 6 hours at 10 krad, and at about 3 hours at 12 krad. More severe hearing impairment was observed at higher frequencies and the endocochlear d.c. potential (EP) decreased at about 7 hours after 10 krad irradiation. Histologically, no discernible changes in the hair cells or sensory hairs were found with a scanning electron microscope at about 6 hours after 10 krad irradiation, while with a transmission electron microscope, the outer hair cells in the basal coil of the cochlea were found to be mostly destroyed. However, no changes could be found in the inner hair cells or other supporting cells.

Long-term sensorineural hearing deficit following radiotherapy in patients suffering from nasopharyngeal carcinoma: A prospective study

“…For radiation-induced inner ear/ auditory nerve damage, metabolic, nutritional, and vascular susceptibility of the auditory apparatus are all possible causes. 4,6 The difference in the incidence and the magnitude of hearing deterioration between high and low frequencies is compatible with previous experience that the basal turn of the cochlea, tonotopically representing the high frequencies, is more vulnerable to injury. The reason for the susceptibility of the hearing ability at high frequencies to damage has not been explored in the literature.…”

“…1 The associated inner ear damage as a result of irradiation to the head and neck region was recognized and then well-documented in animal and human studies. [2][3][4] Most of these studies, however, were retrospective and the follow-up periods were short. 5,6 Also, patients with a wide variety of head and neck cancer were usually included and they were managed with different treatment techniques.…”

Hearing in workers exposed to low-dose radiation for a long period

“…This coincides well with the pathologic findings in animal experiments in which irradiation-induced damage is more pronounced in basal turn of the cochlea (Winther, 1969b;Tokimoto and Kanagawa, 1985). The increase in bone conduction thresholds (obtained in pure-tone audiometry) is assumed to reflect this cochlear dysfunction (Schot et al, 1992;Lau et al, 1992;Moretti, 1976).…”

Risk Factors for Hearing Loss in Patients Treated With Intensity-Modulated Radiotherapy for Head-and-Neck Tumors

“…However, at ultra-high frequencies, the effect of RT in the present study was larger than that observed in our highdose cisplatin chemoradiation regimen, because the radiation effect in the CRT regimen might have been masked by the extensive adverse effect of cisplatin at ultra-high frequencies (26). Although radiation-induced vascular insufficiency has been proposed as the etiology of SNHL (27,28), in animal models, radiation and cisplatin both affected similar targets in the cochlea, including hair cells, stria vascularis, and afferent nerve endings, from basal to apical windings with increasing dose (27)(28)(29)(30)(31)(32)(33). Hence, it could be that cisplatin reinforces the adverse effects of radiation on the inner ear.…”