Ototoxicity

Ototoxicity

1. OTOTOXICITY

2. InTRODUCTION A variety of medication have adverse effects on the cochlea, vestibular apparatus, or cranial nerve 8.The effects of ototoxicity can be reversible and temporary or irreversible and permanent.The effects of certain drugs is temporary,while other drugs typically produce permanent changes to the ear.

3. Definition Ototoxicity is the damage caused by the toxic effects of certain drugs to either cochlear or vestibular or both parts of the inner ear.

4. INCIDENCE The cisplatin   ototoxicity  occurs between 23% and 50% in adults and up to 60% in children .However, some studies have reported elevated hearing thresholds in up to 100% of cisplatin -treated cancer patients while it is estimated to be 63% with aminoglycosides and 6-7% with furosemide .

5. High risk groups Patients having impaired rental function. Elderly patients age above 64 years. Patients simultaneously receiving other ototoxic drugs. Patients who have genetic susceptibility to these group of drugs. Patients under prolonged treatment.

6. Ototoxic Drugs Aminoglycosides Diuretics Antimalarials Anticancer drugs Analgesics Environmental chemicals

7. Aminoglycoside Antibiotics All members of aminoglycoside antibiotic family are well known for their potential to cause permanent ototoxicity if they enter the inner ear. Some of these drugs are more likely to cause hearing loss; others are more likely to cause vestibular loss; others can cause either problem. Aminoglycoside antibiotics can enter the inner ear through the blood system or via diffusion from the middle ear into the inner ear. They enter the blood steam in larger amount when given IV and in the least amount by pill. Eg: Amikacin, Neomycin, Obramycin,steptomycin etc.

8. Loop diuretics Loop diuretics are a specific family of water pills that is known to occasionally cause temporary ototoxicity. These drugs cause ringing in the ears or deceased hearing that reverses when the drug is stopped. Mostly reversible but permanent damage may occur. Eg: Bumetanide ( bumex) Ethacrynic acid (edecrin) Furosemide ( lasix) Torsemide ( demadex)

9. Antimalarials Ototoxic effect is due to vasoconstriction in the small vessels of the cochlea and stria vascularis. The effect is reversible which generally appears on prolonged medication, but deafness is permanent with chloroquine. Congenital deafness and hypoplasia of cochlea have been reported in children whose mother’s received these drugs during pregnancy (first trimester). Eg: Quinine and chloroquine

10. Anticancer drugs Nitrogen Mustards ( cyclophosphamide ,Ifosfamide),Cisplastin,Carboplatin can cause cochlear damage. Ototoxic effect is due to outer hair cell degeneration leading to high frequency sensory neural hearing loss.

11. Analgesics Ototoxic effect is reversible and is due to interference at enzymatic level. No structural damage hence normal histology( no hair cell loss ) Symptoms: Tinnitus and hearing loss NSAIDS like salicylates ,Indomethacin,Phenyl butazone,ibuprofen.

12. ENVIRONMENTAL CHEMICALS Environmental chemicals have long been implicated in ototoxicity. Little research has been done to substantiate their precise effect on ears ,but most are associated with hearing disturbances that may be permanent.

13. CLINICAL MANIFESTATION High pitched tinnitus is often the earliest symptom Sensorineural deafness Vertigo Mild tinnitus to total hearing loss depending upon each person and form and level of exposure to the ototoxin . They can include one sided or two sided hearing loss and constant or fluctuating tennitus .

14. ASSESSMENT AND DIAGNOSIS The diagnosis is based upon the patient‘s history, symptoms, and test results. There is no specific test for ototoxicity ; this makes a positive history for ototoxin exposure crucial to the diagnosis. History collection Physical examination Electrocochleography Eexamination Electrocochleography Electronystagmography Auditory brainstem response

15. TREATMENT At present their are no treatments that can reverse the damage. Currently available treatments focus on reducing the effect of the damage and rehabilitating function. Medical or surgical treatment is usually not effective. Use of ototoxic drugs should be avoided whenever possible. Those with profound bilateral ( two- sided) hearing loss have been shown benifit from Cochlear implants.

16. Usual treatment given for sudden sensori- neural deafness can be advised. Withdrawal of ototoxic drug may prevent further damage in early cases. Hearing aids are advised in clients with established deafness. Tinnitus treated by mild hypnotics.

17. NURSING MANAGEMENT Assess the level of antibiotics to ensure adequate treatment and to prevent ototoxicity. Teach the patient about the complications of priscribed drugs.

18. HEALTH TEACHING Advice the patient to avoid toxic drugs . Advice patient to avoid intake of drugs without priscription. Ask patient to avoid toxic drugs if they are taking any other toxic drugs. Advice patient to avoid contact with environmental chemicals. Teach patient about importence of taking medicine medicines s according to the prescription.

19. COMPLICATION Tinnitus Hearing loss Vertigo Giddiness

20. CONCLUSION Various drugs can result in hearing loss ,which may or may not be reversible.Certain mechanisms are responsible for the hearing loss ,which can either be cochleo or vestibulotoxic.So prevent the chance for toxic effect because ototoxic damage is often times irreversible.

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