An audiological profile of patients infected with multi-drug resistant tuberculosis at a district hospital in KwaZulu-Natal

BACKGROUND The increased incidence of multi-drug-resistant tuberculosis (MDR-TB) and the consequent use of aminoglycosides with their ototoxic potential necessitate a better understanding of the audiological pattern of infected patients. OBJECTIVE To describe the occurrence and nature of hearing loss in patients with MDR-TB receiving aminoglycosides over a period of 6 months. METHODS Baseline and five consecutive monthly audiological assessments were conducted on 52 adults at a hospital in KwaZulu-Natal. A longitudinal descriptive study was implemented. A conventional audiological test battery, extended high frequency audiometry and otoacoustic emission testing were conducted. Data were analysed using SPSS version 19 statistical software package. RESULTS Decreased hearing was the most common audiological symptom experienced. Bilateral sensorineural hearing loss was predominant. Ototoxic hearing loss was noted in 27 participants (52%) in 1 month post-treatment. Hearing loss progressed from mild to moderate at post-treatment one, to moderate to severe at post-treatment three and severe to profound at post-treatment five. Changes in hearing function were noted in 52 participants (100%) by post-treatment five. High and ultra-high frequencies were most affected. Speech discrimination scores deteriorated over time. The number of patients with absent distortion product otoacoustic emissions increased over treatment duration. CONCLUSION The greatest effects were observed in the high frequencies before manifesting in the lower frequencies. This highlights the importance of inclusion of high frequency audiometry in the early detection of ototoxicity which can go undiagnosed with traditional audiometry. The high prevalence of hearing loss has implications for the provision of audiological service to this patient population.