鼻咽癌患者放疗后引起感音神经性聋的临床观察

目的探讨鼻咽癌患者放疗后不同时期感音神经性聋的程度及发生率。方法选择无分泌性中耳炎的鼻咽癌患者28例，利用纯音测听和听性脑干反应（ABR），结合声导抗和耳声发射测试患者放疗前和放疗后1个月、1年、2年和5年的纯音听阈及波Ⅰ、Ⅲ、Ⅴ潜伏期、Ⅰ～Ⅴ波间期、鼓室压和镫骨肌声反射，以及部分受放射耳的诱发性耳声发射。结果语频（0．5～4．0kHz）和高频（8kHz）平均骨导听阈情况：①放疗后1个月较治疗前分别提高7．1dB和25．7dB，与放疗前比较差异有统计学意义（P〈0．001）；②放疗后1年分别提高17．6dB和28．1dB，与放疗前比较差异有统计学意义（P〈0．001），与放疗后1个月比较差异也有统计学意义（P值均〈0．001或P〈0．05）；③放疗后2年分别提高21dB和27．4dB，与放疗后1年比较差异仅语频有统计学意义（P〈0．05）；④放疗后5年分别提高26．7dB和35．8dB，与放疗前、放疗后1个月、1年和2年比较差异均有统计学意义（P值均〈0．001）。其中语频和高频听力损害大于15dB的发生率分别为37．5％～94．7％和85．4％～97．4％；听力损害大于30dB的发生率分别为14．6％～63．2％和37．5％～73．7％。平均ABR波Ⅰ、Ⅲ和Ⅴ潜伏期及Ⅰ～Ⅴ波间期的情况：放疗后1个月与放疗前比较无明显延长（P〉0．05）；放疗后1年和2年，均较放疗前和放疗后1个月明显延长，差异有统计学意义（P〈0．05），1年和2年组比较差异无统计学意义（P〉0．05）；放疗后5年较放疗前显著延长（P〈0．001），与放疗后1年和2年比较，波Ⅰ、Ⅲ和Ⅴ潜伏期明显延长（P〈0．05），而Ⅰ～Ⅴ波间期无明显延长（P〉0．05）。放疗1年后10耳中有7耳，放疗5年后7耳中有4耳诱发性耳声发射正常，但ABR均明显异常。结论放射所致的感音神经性聋可发生在部分患者放疗后的早期，特别是高频；随放疗后时间延长，听力损害的发生率增加，程度加重；损害可发生在耳蜗或（和）蜗后听觉通路，表明听觉系统不同部位和不同个体对放射损伤的敏感性可能存在差异。

Clinical observation of sensorineural hearing loss in patients suffering from nasopharyngeal carcinoma after radiotherapy

OBJECTIVE: To study the extent and incidence of sensorineural hearing loss (SNHL) after radiotherapy (RT). METHODS: Twenty-eight patients with diagnosed nasopharyngeal carcinoma (NPC) were selected. The pure-tone audiography, auditory brain stem evoked response (ABR), impedance audiometry and evoked otoacoustic emissions (EOAE) recordings were performed before RT, 1 month, 1, 2 and 5 years after RT. RESULTS: At 1 month after RT, there were 7.1 and 25.7 dB increased mean bone conduction (BC) thresholds at speech (0.5 - 4.0 kHz) and at high frequency (8.0 kHz), and their BC thresholds were statistically significant increase than those before RT, respectively (P < 0.001). At 1 year after RT, there were 17.6 and 28.1 dB increased respectively, and their thresholds were statistically significant increase than those at pre-irradiation (P < 0.001). There were also significant increases in thresholds than those at 1 month of post-irradiation (P <0.001 or P < 0.05). At 2 years after RT, 21 and 27.4 dB were increased at respective those two frequencies, and there was a statistically difference only at speech frequencies when compared with those at 1 year after RT (P < 0.05). At 5 years after RT, 26.7 and 35.8 dB were increased at these two frequencies, and there were significant increases in threshold than those before, 1 month, 1 and 2 years after RT, respectively (P < 0.001). From 1 month to 5 years after RT, 37. 5% to 94. 7% of ears had a BC hearing threshold of at least 15 dB losses at speech frequency, whereas the percentage at high frequency was 85.4 to 97.4%. Up to 63.2% and 73.7% of ears had 30 dB SNHL at least at speech and high frequency, respectively. Furthermore, the degree of mean threshold loss was greater at high frequency than at speech frequency. The mean value of wave I, III and V latency, and I -V interpeak latency intervals of ABR had no significant difference between at 1 month after RT and before RT (P > 0.05). The wave I , III and V latency, and I - V interpeak latency intervals at 1 year and 2 years were significantly prolonged when compared with those before and 1 month after RT (P < 0.05), but there were no significant difference between 1 year and 2 years after RT (P > 0.05). The wave I, III and V latency, and I -V interpeak latency intervals at 5 years after RT were also significantly longer than those before RT (P < 0.001). There were significant difference in wave I , III and V latency (P < 0.05), and no significant difference in wave I - V interpeak latency intervals (P > 0. 05) between 5 years after RT and 1 year or 2 years after RT. Seven of 10 ears at 1 year after RT and 4 of 7 ears at 5 years after RT had normal EOAE, but they all had abnormal ABR response. CONCLUSIONS: SNHL in NPC patients start soon after completion of RT, especially more commonly in high frequency. The incidence and the extent of hearing loss are increased with time of follow-up. The hearing impairment could occur in the cochlea and/or the retrocochlear auditory pathway, which show that the sensitivity of radiation damage may be different in different patient and anatomic site of auditory system.