Ototoxicity (oto- ear, toxicity-poisoning) is simply ear poisoning which results from exposure to drug or chemicals that damage cochlea, auditory nerve or vestibular system. It also depends on factors such as heredity.
It may be reversible or irreversible and temporary or permanent.
Drugs which causes ototoxicity include loop diuretics such as furosemide and ethacrynic acid, antibiotics such as gentamicin, streptomycin, tobramycin and erythromycin. Platinum containing chemotherapeutic agents like cisplatin and carboplatin, vinca alkaloids including vincristine, NSAIDs (Non-Steroidal Anti-Inflammatory Drugs) are also associated with ototoxicity. Ototoxic effects are also seen with quinine, pesticides and heavy metals such as mercury and lead.
Symptoms include partial or full hearing loss, vertigo and tinnitus.
Cochlea is snail shaped structure containing several nerve endings and is situated in inner ear. It makes hearing possible. Ototoxicity in cochlea may cause hearing loss of high frequency pitch ranges, complete deafness or losses at points between and start or worsening of tinnitus.
Vestibule and semi-circular canals are inner ear component which comprise the vestibular system. Their function is to detect all direction of head movement. Vestibulotoxicity causes loss of balance rather than loss of hearing which causes symptoms like vertigo, difficulty walking in low light.
There is no specific test to diagnose ototoxicity. The diagnosis is based on patient history, symptoms and test results.
There is no specific treatment that can reverse the damage. Withdrawal of ototoxic drugs may be required.
Currently available treatment focus on reducing effects of damage and rehabilitating the function. Physical therapy may be useful for regaining balance and walking abilities. Hearing aids may be helpful to reduce hearing loss.
Bikash is a biologist with background in cell biology, molecular biology, immunology and microbiology. He works as an Analytical Chemist III for a CRO company called Avomeen in Ann Arbor, Michigan, US. He established biologics lab there. He loves to help other companies to solve their problems.
