What is the recommended intratympanic steroid treatment protocol for idiopathic sudden sensorineural hearing loss, including drug choice, dosage, frequency, contraindications, and follow‑up?

Intratympanic Steroid Treatment for Sudden Sensorineural Hearing Loss

Intratympanic steroids should be offered as salvage therapy when hearing recovery is incomplete 2 to 6 weeks after initial treatment, using dexamethasone 5 mg/mL or methylprednisolone 40-62.5 mg/mL, administered as 4-6 injections over 2 weeks. 1

Drug Selection and Dosing

Primary Options

• Dexamethasone 5 mg/mL (most commonly used): 0.4-0.8 mL per injection 1, 2
• Dexamethasone 24 mg/mL (compounded): 0.4-0.8 mL per injection 2, 3
• Methylprednisolone 40 mg/mL: 0.4-0.8 mL per injection 1, 2
• Methylprednisolone 62.5 mg/mL: Higher concentration option with 73.6% improvement rate in salvage therapy 1, 2

The evidence shows considerable variability in steroid selection, but all five randomized controlled trials demonstrating efficacy used either dexamethasone or methylprednisolone. 1 Dexamethasone is preferred in most protocols due to its longer half-life and better round window membrane penetration. 1

Treatment Protocols

Salvage Therapy (Standard Indication)

• Timing: Initiate when hearing recovery is incomplete 2-6 weeks after initial systemic steroid therapy 1
• Frequency: 4-6 injections over 2 weeks (typically twice weekly) 1, 4
• Evidence: Four of five RCTs began intratympanic steroids within 7 days of completing systemic treatment 1
• Optimal window: Starting salvage therapy within 23 days of symptom onset provides superior outcomes compared to later initiation 5

Initial Therapy (When Systemic Steroids Contraindicated)

• Indications: Uncontrolled diabetes, severe hypertension, active peptic ulcer, active tuberculosis, glaucoma, myasthenia gravis, cataracts, or prior psychiatric reactions to corticosteroids 1, 2, 3
• Protocol: Up to 4 injections per ear over 2 weeks 2, 3
• Advantage: Minimal systemic exposure—intratympanic steroids rarely cause glucose elevation even in diabetic patients 1

Injection Technique

Procedure Steps

1. Anesthesia: Apply topical anesthetic to tympanic membrane 2
2. Approach: Perform anterosuperior myringotomy 2
3. Volume: Inject 0.4-0.8 mL into middle ear space 1, 2
4. Positioning: Patient maintains head in otologic position (affected ear up) for 15-30 minutes 2, 3
5. Delivery method: Transtympanic needle perforation is most commonly used 1

Alternative delivery methods include tympanostomy tube placement, microcatheter, or MicroWick, though needle perforation remains standard. 1

Monitoring Requirements

Audiometric Assessment

• Baseline: Obtain audiometry within 14 days of symptom onset to confirm diagnosis 1, 2, 3
• During treatment: Perform audiogram before each subsequent intratympanic injection to monitor response and guide early termination if hearing resolves 2, 3
• Post-treatment: Audiogram at completion of injection series 2, 3
• Final assessment: Repeat audiometry at 6 months post-treatment regardless of perceived recovery 1, 2, 4

Success Criteria

• Improvement defined as: ≥10 dB decrease in pure tone average OR ≥10% improvement in word recognition score 1, 4, 6
• Expected outcomes: 37.5-47.6% of patients show ≥10 dB improvement with salvage intratympanic therapy 1
• Higher concentration protocol: Methylprednisolone 62.5 mg/mL given as 5 injections over 12 days achieved 73.6% improvement in patients who failed systemic steroids 1, 2

Contraindications and Precautions

Absolute Contraindications

• Active middle ear infection 1
• Tympanic membrane perforation (pre-existing) 1

Relative Considerations

• Persistent perforation risk: Rare complication (incidence increases with multiple injections—fifth or higher injection carries 17.47-fold increased risk compared to no injection) 1, 7
• Resolution: Most perforations resolve spontaneously or with paper patch myringoplasty 1

Common Adverse Effects

• Transient pain at injection site 1, 2
• Brief caloric vertigo/transient dizziness 1, 2
• Infection (rare) 2
• Persistent tympanic membrane perforation (rare) 1, 2, 7

Prognostic Factors

Favorable Indicators for Salvage Therapy

• Severe initial hearing loss: Patients with ≥60 dB hearing loss at initial visit show better response to salvage intratympanic therapy 5, 8
• Early salvage initiation: Treatment within 23 days of symptom onset independently predicts favorable outcomes 5
• Presence of vertigo: Paradoxically associated with better response to intratympanic salvage therapy 5
• Low-frequency hearing loss: Intratympanic steroids show particular efficacy at 500 Hz 8

Poor Prognostic Indicators

• Minimal hearing change during first 2 weeks predicts unlikely significant recovery 1, 4
• Presence of vertigo at onset predicts poorer overall prognosis (though better salvage response) 1, 4, 5

Recovery Timeline

• 54.5% of patients who recover show improvement within 10 days of treatment 2, 4
• 78% achieve final hearing level by 1 month 2, 4
• 97% achieve final hearing level by 3 months 2, 4
• Only 0.6% demonstrate recovery beyond 6 months 2, 4

Clinical Algorithm

Decision Pathway

1. Initial presentation: Confirm sensorineural hearing loss with audiometry within 14 days 1, 3
2. First-line therapy: Systemic corticosteroids (prednisone 1 mg/kg/day, max 60 mg, for 7-14 days with taper) within 2 weeks of onset 1, 2, 3
3. Assessment at 2 weeks: Evaluate hearing recovery
   • If complete recovery: Follow-up audiometry at 6 months 1, 4
   • If incomplete recovery: Proceed to salvage intratympanic therapy 1
4. Salvage protocol: 4-6 intratympanic injections over 2 weeks 1, 4
5. Final assessment: Audiometry at completion and 6 months 1, 2

Alternative Pathway (Systemic Steroids Contraindicated)

1. Initial therapy: Intratympanic steroids as primary treatment 2, 3
2. Protocol: Up to 4 injections over 2 weeks 2, 3
3. Monitoring: Audiogram before each injection 2, 3

Common Pitfalls to Avoid

• Do not delay salvage therapy: Initiate within 23 days of symptom onset for optimal results; efficacy decreases significantly after this window 5
• Do not skip interim audiometry: Perform audiograms before each injection to detect early recovery and avoid unnecessary additional injections 2, 3
• Do not assume systemic contraindications apply to intratympanic route: Intratympanic steroids can be safely used in diabetics, patients with glaucoma, and those with other systemic contraindications 1, 2
• Do not rely on patient-reported improvement: Objective audiometry is essential—patients cannot accurately assess degree or type of hearing recovery 4
• Do not stop at 2 weeks if no improvement: Recovery may continue up to 3 months, with 21.8% of recoverers showing delayed improvement between 1-3 months 2, 4
• Do not omit 6-month follow-up: Even with perceived complete recovery, repeat audiometry is necessary to document final outcome and screen for retrocochlear pathology 1, 2, 4

Cost and Practical Considerations

• Higher cost than systemic steroids: Intratympanic therapy requires multiple clinic visits and procedural fees 1
• Time commitment: Patients must maintain head position for 15-30 minutes per injection 2, 3
• Repeat injections increasingly common: National trends show rising use of multiple injections, but fifth or higher injection significantly increases perforation risk 7