[Ototoxicity-related dysequilibrium]

Many substances may be the source of dizziness or transient equilibrium disturbances due to dysfunction of the CNS or to an impairment of visual or proprioceptive informations. Other agents are responsible for drop of arterial pressure by changing position, including antihypertensive drugs, alpha-blocking agents used in urology, antipsychotics, cyclic antidepressants, vasodilators and nitrates, dopaminergic antiparkinson drugs, sedatives, etc. Only drug with true ototoxic properties will be discussed here, namely substances that are able to damage the inner ear (cochlear or vestibular damage) or the VIIIth cranial nerve, causing impairment of equilibrium and/or (most often) hearing. No relevant data report the actual incidence of ototoxic problems, but more than 130 products have been classified as potentially dangerous. Individual susceptibiity seems highly variable, but some predisposing factors have been identified: renal failure, age, combination of ototoxic drugs, familial sensitivity to ototoxic effects or previous neurosensorial deficit. We will first discuss the ototoxic medications that have certainly been extensively studied and among which we find several antibiotics (especially aminoglycosides and macrolides), the loop diuretics, and some antimalarial or chemotherapeutic agents. Environmental toxins and drug of abuse will then be discussed briefly because scientific data are much less significant. Early recognition of subjects who are at risk of developing ototoxicity, use of therapeutic monitoring and close observation of cochleo-vestibular functions in high risk situations (often not easy in critical patients) are the best way to prevent severe complications that have occasionally disastrous consequences on the quality of further life.