Can Tuberculosis (TB) drugs cause sensorineural hearing loss?

Tuberculosis Drugs and Sensorineural Hearing Loss

Yes, several tuberculosis (TB) drugs, particularly aminoglycosides, can cause sensorineural hearing loss, with the risk being highest for amikacin (33.4%), followed by kanamycin, streptomycin, and lowest for capreomycin (2.0%). 1

Aminoglycoside Ototoxicity

Mechanism and Risk

• Aminoglycosides (streptomycin, amikacin, kanamycin) and polypeptides (capreomycin) can cause irreversible damage to the vestibular branch of the eighth cranial nerve, resulting in ototoxicity 2
• Ototoxicity can be vestibular (affecting balance) or cochlear (causing hearing loss) 2
• The risk of hearing loss increases with:
  • Higher doses and longer duration of treatment 3, 4
  • Advanced age 3, 4
  • Pre-existing renal dysfunction 2
  • Concurrent use of other ototoxic drugs (loop diuretics like furosemide, ethacrynic acid) 3, 2
  • Certain mitochondrial DNA variants, particularly the m.1555A>G variant in the MT-RNR1 gene 3

Drug-Specific Ototoxicity Profiles

Streptomycin

• Primarily causes vestibular dysfunction (vertigo, ataxia, nystagmus) but can also cause hearing loss 2
• Risk increases with cumulative doses above 100-120g 2
• Ototoxicity can progress even after discontinuation of the drug 2
• Contraindicated in pregnancy due to risk of fetal hearing loss 2

Amikacin and Kanamycin

• Higher risk of cochlear toxicity (hearing loss) compared to vestibular toxicity 2
• Amikacin has the highest reported incidence of hearing loss (33.4%) among TB injectable drugs 1, 5
• High-frequency hearing loss was observed in 24% of patients receiving amikacin in one study 2
• Kanamycin showed ototoxicity in 18% of patients after 6 weeks of therapy in one study 6

Capreomycin

• Has the lowest reported incidence of ototoxicity (2.0%) among injectable TB drugs 1, 5
• Still carries risks of nephrotoxicity and ototoxicity 2

Monitoring and Prevention

Recommended Monitoring

• Baseline audiogram, vestibular testing, Romberg testing, and serum creatinine measurement before starting treatment 2
• Monthly assessment of renal function and questioning about auditory or vestibular symptoms 2
• Regular high-quality audiometry, especially for high-frequency hearing loss which occurs early 2
• Repeat audiogram and vestibular testing if symptoms of eighth nerve toxicity develop 2

Risk Mitigation Strategies

• Dose adjustment in elderly patients and those with renal impairment 2
• Monitoring serum drug levels to avoid toxicity, especially with amikacin where measurements are readily available 2
• Consider alternative treatments in patients with known mitochondrial DNA variants or family history of aminoglycoside ototoxicity 3
• Early detection and discontinuation may prevent irreversible damage 3

Clinical Implications

Treatment Considerations

• In MDR-TB treatment, amikacin has shown better treatment success rates compared to kanamycin and capreomycin, despite higher ototoxicity risk 2
• The benefit of injectable agents must be weighed against the significant risk of permanent hearing loss 1, 5
• Recent guidelines recommend considering aminoglycoside-sparing regimens when possible, especially for patients at high risk of ototoxicity 4
• When aminoglycosides must be used, single daily dosing is preferred to divided doses to minimize toxicity while maintaining efficacy 2

High-Risk Populations

• Patients with pre-existing hearing loss have 1.71 times higher risk of developing additional hearing loss 4
• Risk increases by 16% for every 10 years of age 4
• Patients receiving high doses (≥75 mg/kg/week) have 1.33 times higher risk of requiring regimen modification due to ototoxicity 4
• Patients with diabetes, hypertension, and lower socioeconomic status may be at higher risk 6

Prevention of Hearing Loss

• Non-use of aminoglycosides could prevent approximately 50,000 cases of hearing loss annually worldwide 5
• When aminoglycosides must be used, close monitoring and early intervention are essential 1
• Newer MDR-TB regimens that avoid injectable agents should be considered when available 5