No abstract

Though brainstem audiometry is one of the most important investigations in pediatric audiology, it often necessitates sedation or general anaesthetics, especially in newborns and infants. Melatonin, inducing natural sleep without the risks of sedation, has been successfully used to induce sleep prior to EEG investigations. 250 children (142 male, 108 female) with suspected hearing loss underwent ABR (auditory brainstem responses) tests in melatonin-induced sleep. Click-induced and notched-noise ABR tests were performed. Click tests were successfully performed in 216 of 249 children or 86.7% (123 male, 93 female), notched-noise tests in 115 of 155 children or 74.2%. Failure rates showed an age dependence increasing from 4% in children <1 year to 25%>3 years, but no gender difference. In conclusion, melatonin-induced sleep is a good alternative to sedation, especially in children younger than 3 years. This method is widely accepted by parents and permits earlier diagnosis of hearing impairment in a routine clinical setting. The number of children undergoing general anaesthesia for ABR investigation was reduced from over 60 per year in 2000-2002 to 12 in 2005, which means >80% less general anaesthesia.

Neuroanatomical and -radiological studies have converged to suggest an atypical organisation in the temporal bank of the left-hemispheric Sylvian fissure for dyslexia. Against the background of this finding, we applied high temporal resolution magnetoencephalography (MEG) to investigate functional aspects of the left-hemispheric auditory cortex in 11 right-handed dyslexic children (aged 8-13 years) and nine matched normal subjects (aged 8 -14 years). Event-related field components during a passive oddball paradigm with pure tones and consonant -vowel syllables were evaluated. The first major peak of the auditory evoked response, the M80, showed identical topographical distributions in both groups. In contrast, the generating brain structures of the later M210 component were located more anterior to the earlier response in children with dyslexia only. Control children exhibited the expected activation of more posterior source locations of the component that appeared later in the processing stream. Since the group difference in the relative location of the M210 source seemed to be independent of stimulus category, it is concluded that dyslexics and normally literate children differ as to the organisation of their left-hemispheric auditory cortex.

Ototoxicity is a common side effect of platinum treatment and manifests as irreversible, high-frequency sensorineural hearing loss. Genetic association studies have suggested a role for SNPs in genes related to the disposition of cisplatin or deafness. In this study, 429 pediatric patients that were treated with cisplatin were genotyped for 10 candidate SNPs. Logistic regression analyses revealed that younger age at treatment (≤5 years vs >15 years: OR: 9.1; 95% CI: 3.8-21.5; P = 5.6 × 10 −7 ) and higher cumulative dose of cisplatin (>450 vs ≤300 mg/m 2 : OR: 2.4; 95% CI: 1.3-4.6; P = 0.007) confer a significant risk of ototoxicity. Of the SNPs investigated, none of them were significantly associated with an increase of ototoxicity. In the meta-analysis, ACYP2 rs1872328 (OR: 3.94; 95% CI: 1.04-14.03; P = 0.04) and SLC22A2 rs316019 (OR: 1.46; 95% CI: 1.07-2.00; P = 0.02) were associated with ototoxicity. In order to increase the understanding of the association between SNPs and ototoxicity, we propose a polygenic model, which takes into account multiple interacting genes of the cisplatin pathway that together confer an increased risk of ototoxicity.

The cochlear radiation dose should be kept as low as possible in patients who receive simultaneous cisplatin-based chemotherapy. The risk of clinically relevant HL was shown when D exceeds 45 Gy independent of radiation technique or radiation regime. Cisplatin ototoxicity was shown to have a dose-dependent effect on bilateral SNHL, which was more pronounced in higher frequencies.