What is the role of intratympanic (into the middle ear) injections in treating sudden sensorineural hearing loss?

Role of Intratympanic Injections in Treating Sudden Sensorineural Hearing Loss

Intratympanic steroid injections should be offered as salvage therapy for patients with sudden sensorineural hearing loss (SSNHL) who have incomplete recovery after initial systemic steroid treatment. 1

Indications for Intratympanic (IT) Steroid Therapy

• Primary indications:

  • Salvage therapy after failure of initial systemic steroid treatment
  • First-line therapy for patients who cannot tolerate systemic steroids (diabetes, hypertension, glaucoma, etc.) 2

• Timing:

  • Most effective when initiated within 2-6 weeks after onset of symptoms
  • Should be started within 2-7 days after completion of systemic treatment for optimal results 1

Efficacy of Intratympanic Steroid Therapy

• Success rates as salvage therapy:

  • 37-48% of patients show significant hearing improvement 1, 2
  • Meta-analysis shows mean improvement of 13.3 dB compared to placebo (p<0.0001) 1
  • Hearing improvement criteria:
    • 10 dB improvement: 37.5-47.6% of patients 1
    • 15 dB improvement: 45.9% of patients 1

• Comparison studies:

  • Wu et al. showed 44.4% improvement with IT steroids vs 10.7% in control group 1
  • Li et al. demonstrated 37.5% improvement with IT steroids vs 0% in control group 1
  • A 2011 randomized, double-blind, placebo-controlled study showed 44.4% of patients improved by ≥10 dB with IT steroids vs only 10.7% with placebo 3

Administration Protocol

• Recommended regimen:

  • 4-6 injections over a 2-week period 1, 2
  • 0.4-0.8 mL of steroid solution per injection 2
  • Patient positioned with affected ear up for 15-30 minutes after injection 2

• Medication options:

  • Dexamethasone (4-24 mg/mL)
  • Methylprednisolone (40-62.5 mg/mL)
  • Methylprednisolone may have superior outcomes (84% improvement) compared to dexamethasone (64% improvement) 2
  • Higher concentrations of dexamethasone (24 mg/mL) show better results than lower concentrations (10 mg/mL) 2

Delivery Techniques

• Common methods:

  • Transtympanic needle perforation (most common)
  • Myringotomy with or without tympanostomy tube placement
  • Endoscopic diode laser myringotomy 4

• Specialized delivery systems:

  • Microcatheters
  • MicroWick
  • Hydrogel applications
  • Nanoparticles 1

Potential Side Effects

• Transient pain at injection site
• Brief vertigo (caloric effect)
• Tympanic membrane perforation (rare)
• Infection (rare)
• Vasovagal or syncopal episode during injection 2
• Risk of hearing deterioration (rare) 4

Follow-up Protocol

• Audiometric evaluation at:
  • 1 month (90% of final hearing levels reached)
  • 3 months (98.3% of final hearing levels reached)
  • 6 months (to assess stability) 1, 2

Clinical Pearls and Pitfalls

• Important considerations:

  • Early intervention is critical for better outcomes
  • IT steroids provide a targeted approach with minimal systemic side effects
  • Can be used as primary therapy when systemic steroids are contraindicated
  • Methylprednisolone may cause more injection-site pain than dexamethasone but may be more effective 5

• Pitfalls to avoid:

  • Delaying salvage therapy beyond 6 weeks from symptom onset
  • Using inadequate steroid concentrations
  • Insufficient number of injections
  • Inadequate post-injection positioning

Treatment Algorithm

1. For new-onset SSNHL:

   • If patient can tolerate systemic steroids: Start with oral prednisone (1 mg/kg/day, max 60 mg) for 7-14 days
   • If contraindications to systemic steroids exist: Proceed directly to IT steroid injections 2

2. For incomplete recovery after initial treatment (2-6 weeks from onset):

   • Offer IT steroid injections as salvage therapy
   • Administer 4 injections over 2 weeks 1, 2

3. For severe hearing loss (70-89 dB HL):

   • Consider combined therapy (systemic + intratympanic) for primary treatment as this shows significantly higher success rates (55% vs 34% with systemic steroids alone) 5