[Iatrogenic and non-iatrogenic factors as causes of progressive sensorineural hearing loss]

The aim of our study was to analyze factors such as noise, chemical drugs, industrial solvents and radiotherapy, which can cause cochlear lesions with progressive sensorineural hearing loss. Although an acute overstimulation by acoustic energy may induce an irreversible hearing loss, in most cases the noise-induced deafness is related to the duration of the exposure and to the level of the acoustic stimulation. A permanent hearing deficit occurs when the acoustic level exceeds 85 dBs. Also several classes of drugs are described as having ototoxic potential: aminoglycoside antibiotics, loop diuretics, antimalarial drugs such as quinine, salicylates, some chemotherapeutic antineoplastic agents. Their potential ototoxic effect seems to be related not only to the molecule, but also to individual predisposition, dose and route of administration. Regarding the benzene derivatives, there is a relationship between their ototoxicity and factors such as duration of exposure and concentration in the local environment. Finally, radiotherapy to areas near the temporal bone may produce a degenerative insult to the vascular stria and the hair cell causing a progressive sensorineural hearing loss.