The prevalence of hearing loss in children and adolescents with cancer

Revista Brasileira de Otorrinolaringologia

Latorre, Maria do Rosário Dias de Oliveira¹  Cristofani, Lilian Maria¹  Silva, Aline Medeiros da¹  USP¹  Instituto de Tratamento do Câncer Infantil¹  Odone Filho, Vicente¹ 

关键词: childhood cancer;    ototoxicity;    hearing loss;    chemotherapy.;   

DOI  :  10.1590/S0034-72992007000500005

学科分类：医学（综合）

来源: Associacao Brasileira de Otorrinolaringologia e Cirurgia Cervicofacial

【 摘 要 】

The increase in survival rates of children and adolescents with malignant tumors in the last two decades reflects more effective treatments - including combined chemotherapy, better diagnostics, better surgical techniques and radiotherapy, the combined use of different treatment modalities, better support and increase in survival and quality of life1-3. Nonetheless, children and teenagers with cancer are exposed to the most diverse sort of side effects, especially when submitted to chemotherapy, which despite being one of the most promising means to fight cancer, depending on the chemotherapeutic agents employed it can cause undesirable side effects.Side effects may manifest themselves earlier on, or in the long run, depending on treatment type and childÂ’s age. Hearing loss is among these many side effects4,5.Ototoxicity is defined as a toxic reaction that affects the inner ear, both the auditory and/or the vestibular system and may cause hearing loss6. Ototoxicity has taken an important role, especially in younger children, having seen that it is usually irreversible and, thus, it means a loss in the long run7,8.One commonly used classification to assess hearing losses in audiology clinics is the one from Davis and Silverman (1970), mentioned by Russo and Santos (1993)9. It is based on determining the degree of hearing loss from air conduction threshold average in the frequencies of 500, 1000 and 2000 Hz - the ones most important for speech, considering normal hearing until 25 dBHL (decibel hearing level). However, this classification is the same for adults and children, regardless of the disease, and today we also consider the frequency of 4,000 Hz as being important.According to Haggard and Primus (1999)10, the scales used to classify hearing loss are not similar, and such fact makes it difficult to compare prevalence. There is much disagreement on which would be the most adequate classification to use for hearing loss, however the consensus is that it is important to adopt a differentiated hearing loss classification for children. According to Northern and Downs (1989)11, the ideal tonal threshold for a child is 15 dB or less in all audiogram frequencies (from 250 to 8000 Hz), differently from adults, in which the mean value between 20-25 dB is acceptable.In assessing the childÂ’s hearing loss, it is important to highlight that even mild loss, which would not impact adults, may interfere in childrenÂ’s capacity to acquire and develop language skills. Hearing loss, even if transitional, between 25 and 35 dBHL, this reduction is not enough to prevent the child from hearing, however, it may impair the childÂ’s ability to understand some phonema11.In 1991, the American Speech-Language-Hearing Association - ASHA (Hersh and Johnson, 2003)12 proposed a hearing loss classification for children. Hearing loss is determined according to the different degrees of difficulty for communication, considering normal hearing the one between 10 and 15 dBHL, mild hearing loss between 16 and 25 dBHL, light hearing loss between 26 and 40 dBHL, moderate hearing loss between 41 and 55 dBHL, moderately severe hearing loss between 56 and 70 dBHL, severe hearing loss between 71 and 90 dBHL and profound hearing loss those above 90 dBHL.In 1994, the American Speech-Language-Hearing Association - ASHA proposed another specific classification for patients treated with ototoxic drugs, the Ototoxicity Criteria (ASHA, 1994)13. Such classification classifies hearing loss by means of comparing the results of previous audiologic evaluations, in A (threshold increase in 20 dB or more in one frequency), B (threshold increase in 10 dB or more in two sequential frequencies) and C (no response in three sequential frequencies, which were present in prior audiologic evaluations).According to Brock et al. (1991)8, hearing loss specifically induced by cisplatin has been measured by pre and post treatment audiograms. Notwithstanding, the existing classifications for hearing loss are not adequate to be used in children with cancer, since the most common classifications usually determine the degree of hearing loss based on the mean value of air conduction in the frequencies of 500, 1000 and 2000 Hz (as the classification from Davis and Silverman, 1970). Thus, the authors proposed an exclusive classification for children treated with cisplatin or other ototoxic drugs. In such classification, hearing loss is classified in levels, according to the frequency that presented tonal threshold below 40 dBHL: Level 0 (hearing thresholds below 40 dBHL in all the frequencies), Level 1 (hearing loss above or equal to 40 dBHL in 8000 Hz), Level 2 (Hearing loss above or equal to 40 dBHL in 4000 Hz and below), Level 3 (hearing loss above or equal to 40 dBHL in 2000 Hz and below) and Level 4 (hearing loss above or equal to 40 dBHL in 1000 Hz and in lower frequencies). The classification proposed considers that hearing loss above or equal to 40 dBHL, in any frequency, implies loss in speech recognition and, the more it affects speech frequencies, the more harm it brings. The authors consider that after 40 dBHL the hearing loss was surely caused by an external agent, the ototoxic drug in this

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