Ototoxicity

Ototoxicity refers to drug- or chemical-induced damage to the inner ear structures, specifically the cochlea (hearing), vestibular system (balance), or vestibulocochlear nerve. The term combines "oto" (ear) with "toxicity," literally meaning "ear poisoning." This condition can result in permanent or temporary hearing loss, tinnitus (ringing), vertigo, imbalance, and spatial disorientation.

Major classes of ototoxic medications include aminoglycoside antibiotics (gentamicin, streptomycin, tobramycin), platinum-based chemotherapy agents (cisplatin, carboplatin), loop diuretics (furosemide, ethacrynic acid), and high-dose salicylates or NSAIDs. Aminoglycosides cause permanent cochleotoxicity by destroying hair cells through oxidative stress, while cisplatin generates free radicals that damage both cochlear and vestibular structures.

Risk factors include high doses, prolonged therapy, concurrent use of multiple ototoxic drugs, pre-existing kidney disease, advanced age, and genetic susceptibility including mitochondrial DNA mutations. Symptoms may develop during treatment or emerge weeks after discontinuation, with some cases showing delayed progression.

Prevention involves monitoring drug levels, using alternative medications when possible, baseline and serial audiometry, and early detection through distortion product otoacoustic emissions testing. Once hair cells are destroyed, damage remains irreversible, emphasizing the importance of vigilance during ototoxic therapy.