1. MANAGEMENT OF OTOTOXICITY
OUTLINE
History
Examination
Investigations
Diagnosis
Differential diagnosis
Prevention and monitoring
Treatment
Prognosis
Follow up
Recent advances
Conclusion

2. HISTORY
Detailed history is required to - Establish a diagnosis - Ascertain severity of the condition - Identify those at risk Bio data - Age The following symptoms are looked out for and evaluated > Tinnitus – most often the first symptom > Hearing loss > Imbalance or vertigo

4. > History of intake of ototoxic drugs (type, dose & duration)
> History of intake of ototoxic drugs (type, dose & duration). > History of risk factors -- impaired renal function -- impaired liver function --history of previous intake of ototoxic agents -- family history of ototoxicity Recent organ transplantation.

5. Examination General examination Ear examination
-- otoscopy- usually normal except in pre existing pathology like csom – TM perforation ± discharge etc
-- Tuning fork test
-SNHL
-Rhinne test –positive
- Weber test – lateralized to better ear

6. Vestibular function test – for those who present with vertigo or sense of imbalance. - Hallpike manoeuvre - Romberg test R/o other causes of vertigo -fistula test

7. Investigations Pure tone audiometry – High frequency
Otoacoustic emissions
Brainstem evoked response audiometry
Electrocochleography – measures the signals produced by the cochlea and cochlear nerve in response to acoustic stimulus
Caloric test
- canal paresis
- unilateral preponderance

8. Diagnosis From history - reveals intake of ototoxic medication
Diagnosis is by exclusion
OAEs, high frequency PTA, BERA & electrocochleography reveal cochlear damage but not specifically ototoxicity

9. Differential diagnosis
Sudden hearing loss
Presbyacusis
Acoustic neuroma.

10. Prevention and monitoring
Ototoxicity is preventable
Ototoxic damage is often times irreversible
Treatment poses a great challenge
Prevention is therefore highly advocated
Measures
Avoidance of ototoxic drugs
Awareness – clinicians should be aware of drugs with ototoxic potentials

11. Recognition of at risk groups e.g.
- previous history of ototoxicity
- family history of ototoxicity
- elderly
- impaired kidney or liver function
- patients already on ototoxic medication
Recent organ transplantation

12. Recognition of at risk group allows the modification of therapeutic regimen.
Protection against ototoxicity.
- Co-administration of antioxidants or iron chellators.
- otoprotective agents; vitamin A, alpha lipoic acid, gingko biloba.
- study by Kocyigit et al suggested that the antioxidant N-acetyl- cysteine can protect against Amikacin toxicity

13. Avoidance of noisy environment.
Monitoring of serum levels of ototoxic agents.
Audiologic monitoring.
- Pure tone audiometry
- Otoacoustic emissions
- Brain stem evoked response audiometry.
- Electrocochleography
No official guideline for audiologic monitoring.
Routine monitoring is unnecessary unless patient is at risk of ototoxicity.
Interval of testing should decrease with the first sign of ototoxic damage.

14. TREATMENT
Medical
- labyrinthine vasodilators.
- labyrinthine sedatives
- tinnitus maskers
- vestibular rehabilitation exercises.
Amplification – use of hearing aids.
Surgical
- Cochlea implants.

15. PROGNOSIS Depends on ; - the ototoxic agent.
- nature of ototoxicity- reversible, irreversible, progressive.
- severity of the toxicity.
For those that can benefit from amplification, prognosis is good.
Cochlear implant where available and affordable increases prognosis.

16. RECENT ADVANCES. Hair cell regeneration.
- Possibility of hair cell recovery is recently an area of active interest.
-Avian inner ear has demonstrated regenerative capacity of hair cells after gentamicin exposure.
- Role of regenerated hair cell in relation to functional recovery is yet to be clearly defined.
-Further studies needed.
Otoprotection.
- another area that requires further study.

17. CONCLUSION.
Ototoxicity is a preventabe cause of severe morbidity which is usually difficult to manage.
The emphasis should be on prevention.