EVALUATION OF THE COCHLEAR FUNCTIONS WITH OTOACOUSTIC EMISSION IN PATIENTS IRRIADIATED FOR NASOPHARYNGEAL CARCINOMA

Objective: Our purpose was to find out effect of radiation therapy app- lied for nasopahyngeal carcinoma on the middle and inner ear functions. Methods: Sixty-six ears of 33 patients who were scheduled for radiation therapy for nasopharyngeal carcinoma were included in the study. The inclu- sion criteria were a normal otoscopic examination and tympanogram, a lack of conductive deafness on pure tone audiometry, and a lack of a history of previous otologic surgery or ototoxicity. Patients who had middle ear effu- sion in the follow up were excluded. Pure tone and speech audiometry, tym- panometry and otoacoustic emission (OAE) testing were performed. Each patient was irradiated with a total dose of 7000 cGy. Co-60 (Theratron-780 Canada) was used in the radiotherapy, and a total of 7000 cGy was given. Results: In the 9-month follow up, 63.6% of the patients were exclu- ded from the calculations due to the development of middle ear effusi- on. The PTAs of bone conduction were 16.1 dB and 20 dB before and 9 months after radiotherapy, respectively (p>0.05). The frequency spe- cific pure tone results obtained before and 9 months after radiotherapy were not significantly different (p>0.05). The results of TEOAE testing during the follow up were not significantly different (p>0.05). There was no significant change in the DPOAE results (p>0.05) except for in the 2 Hz frequency region, where a significant amplitude reduction was observed in the 9th month compared to the initial recording (p=0.03). Conclusion: Cochlear damage can occur in the short term after radiati- on treatment for nasopharyngeal carcinoma. This damage, which occurs in the middle portion (2 kHz region) of the cochlea, is at subclinical level and does not lead to a hearing loss detectable by audiometry. The impact of radiation therapy on the inner ear may vary, depending on the appli- cation of different radiotherapy protocols in nasopharyngeal carcinoma. Key Words: Nasopharyngeal Carcinoma, Otoacoustic Emissions, Audio- metry, Ear, Radiotherapy. NAZOFARENGEAL KARSINOMA ICIN RADYOTERAPI ALMIŞ HASTALARDA KOHLEAR FONKSIYONLARIN OTOAKUSTIK EMISYON ILE DEĞERLENDIRILMESI Amac: Calismanin amaci nazofarenks karsinomlari tedavisinde uygulanan radyoterapinin orta ve ic kulak fonksiyonlari uzerine etkisini arastirmakti. Metod: Nazofarenks kanseri nedeniyle radyoterapi planlanan 33 hastanin 66 kulagi calismaya alindi. Calismaya alinma kriterleri sunlardi; normal otoskopik muayene bulgulari ve timpanogram; saf ses odyometrisinde ile- tim tipi isitme kaybi olmamasi; ototoksisite veya gecirilmis kulak cerrahisi hikayesi olmamasi. Takip surecinde efuzyonlu otitis media geciren hastalar calisma disi birakildi. Hastalara saf ses ve konusma odyometrisi, timpano- metri ve otoakustik emisyon testi uygulandi. Her hastaya Co-60 (Theratron- 780 Canada) cihazi kullanilarak toplam 7000 cGy radyoterapi uygulandi. Bulgular: Dokuz aylik takip suresinde, orta kulakta efuzyon gelismesi nedeniyle hastalarin %63.6’si calisma disi birakildi. Hastalarin radyoterapi oncesi 16.1 dB olan sas ses ortalamalari RT sonrasi 9. ayda 20 dB olarak bulunmustur (p>0.05). RT oncesi ve sonrasi frekans spesifik saf ses ortalamalari arasinda anlamli fark bulunamamistir(p>0.05). Calis- ma suresince elde edilen TEOAE degerleri arasinda anlamli fark bulu- namamistir (p>0.05). DPOAE sonuclarinda ise 2 Hz frekansinda bas- langic ve 9.ay degerleri disinda anlamli fark bulunamamistir(p=0.03). Sonuc: Nazofarenks kanserli olgularda radyoterapi sonrasi kisa donemde kohlea hasari olusabilir. Ozellikle kohleanin orta bolgesi (2 Hz ) subklinik duzeyde, isitme kaybi sikayetine neden olmaksizin, odiometrik olarak tespit edilebilecek sekilde hasar gorebilir. Nazofarenks kanserinde radyoterapinin ic kulaga etkisi uygulanan protokellere gore degiskenlik gosterebilmektedir Anahtar Kelimeler: Nazofarenks Kanseri, Otoakustik Emisyon, Odyo- metri, Kulak.