Effect of intratympanic dexamethasone administration on cisplatin-induced ototoxicity in adult guinea pigs.

OBJECTIVE: To evaluate the effect and safety of intratympanic dexamethasone administration on cisplatin-induced ototoxicity in adult male guinea pigs and to assess the differences between early and late protection from this ototoxicity. METHODS: Forty eight adult male guinea pigs were divided as follows: group I served as control group. Group II was subjected to intratympanic saline (subgroup IIa) or dexamethasone (subgroup IIb) injection. Group III was intraperitoneally injected with cisplatin. Groups IV and V were subjected first to intratympanic dexamethasone administration in both ears for 5 days starting 1 day and 1h - respectively - before cisplatin intraperitoneal injection. RESULTS: Dexamethasone intratympanic injection revealed similar functional and structural results compared with control. Cisplatin intraperitoneal injection resulted in a profound cochlear functional and structural damage in group III. Non-significant otoprotection resulted from intratympanic dexamethasone administration one day before cisplatin. Intratympanic dexamethasone injection 1h before cisplatin treatment resulted in a significant preservation of the functional and structural properties of the cochlea. CONCLUSION: Intratympanic dexamethasone administration is a safe, easy and efficient way to protect from cisplatin ototoxicity especially when administered 1h before cisplatin treatment.

Cortical auditory evoked potential (P1): a potential objective indicator for auditory rehabilitation outcome.

OBJECTIVE: Cortical auditory evoked potentials are a non-invasive tool that can provide objective information on maturation of the auditory pathways. This work was designed to study the role of cortical auditory evoked potential (P1) in assessment of the benefits of amplification and aural rehabilitation in hearing impaired children. DESIGN: The study consisted of 31 children classified into 2 groups. Study group included 18 hearing impaired children ranging in age 4-14 years old and classified into two subgroups according to adequacy of aural rehabilitation. A control group consisted of 13 normal hearing children ranging in age from 5 to 13 years. All children were subjected to history taking, basic audiological evaluation, intelligence quotient and language assessment. Cortical auditory evoked potential (P1) was measured using synthesized speech syllable /da/ as a recording stimulus that was presented binaurally via a loudspeaker. RESULTS: P1 was recorded in all children with significantly prolonged latencies in hearing impaired children with inadequate rehabilitation. P1 latency was correlated to hearing loss duration in hearing impaired children with inadequate aural rehabilitation. Auditory experience was correlated with P1 latency in hearing impaired children with adequate aural rehabilitation. CONCLUSION: Cortical auditory evoked potential (P1) might provide a clinical tool to monitor aural rehabilitation outcome and to guide intervention choices.