Early changes of auditory brain stem evoked response after radiotherapy for nasopharyngeal carcinoma—A prospective study

Abstract

A prospective study of the effect of radiotherapy for nasopharyngeal carcinoma on hearing was carried out on 49 patients who had pure tone, impedance audiometry and auditory brain stem evoked response (ABR) recordings before, immediately, three, six and 12 months after radiotherapy. Fourteen patients complained of intermittent tinnitus after radiotherapy. We found that 11 initially normal ears of nine patients developed a middle ear effusion, three to six months after radiotherapy. There was mixed sensorineural and conductive hearing impairment after radiotherapy. Persistent impairment of ABR was detected immediately after completion of radiotherapy. The waves I-III and I-V interpeak latency intervals were significantly prolonged one year after radiotherapy. The study shows that radiotherapy for nasopharyngeal carcinoma impairs hearing by acting on the middle ear, the cochlea and the brain stem auditory pathway.

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). Pure-tone audiometric thresholds can be altered by auditory nerve and brain stem pathology and do not reflect cochlear function only.…”

“…The published studies show conflicting results: damage can occur either immediately or later on. Radiation can cause two kinds of hearing impairment; conductive hearing loss originating in the outer and middle ear, and sensorineural hearing loss caused by damage to the cochlea and auditory nerve (Honore et al, 2002;Schot et al, 1992;Lau et al, 1992).…”

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

“…This is one possible suggestion why the ability to hear high-frequency sound is more susceptible to all sorts of insults. 16 At the follow-up interval of 2 years, significant recovery of more than 10 dB at both 4 kHz and PTAv was present in about 40% of ears with early deterioration. This occurred because the acute effect of irradiation subsided after recovery with time.…”

Sensory neural hearing loss after concurrent cisplatin and radiation therapy for nasopharyngeal carcinoma

“…(2) It usually develops within 6 -12 months after radiation therapy [4]. (3) Higher frequencies were more commonly affected than lower frequencies [2,13,20]. There is a radiation induced pathophysiologic changes of the auditory system starting from the Eustachian tube to the brain stem [1,3,13,17] and the mechanism of SNHL is not clear.…”