Chemical Cauterisation in Tympanic Membrane Perforations - OPD Procedure

Mechanism of Action

"Chemical cauterization destroys the squamous epithelium that has grown over the rim of the perforation and in so doing exposes fibroblasts and promotes healing of the lamina propria."

• Shambaugh Surgery of the Ear

Patient Selection

• Small central tympanic membrane perforations (< 4 mm diameter)
• Dry ear (no active discharge)
• Cooperative patient
• Intact, mobile ossicular chain

• Marginal perforations (risk of cholesteatoma)
• Active middle ear infection / otorrhoea
• Cholesteatoma
• Small or narrow external auditory canal (limits access)
• Conductive hearing loss from ossicular pathology
• Extensive tympanosclerosis in the tympanic membrane remnant
• Poor Eustachian tube function

Chemical Agents Used

Step-by-Step Procedure

1. Preparation: Clean the external auditory canal of any debris or discharge using otologic suction under the operating microscope.
2. Visualisation: Perform the procedure under the operating/otologic microscope (or an endoscope in modern practice) for accurate application. Adequate illumination and magnification are essential to confine cauterisation strictly to the rim.
3. Application of TCA:
   • Prepare a metallic applicator with a very small amount of cotton wound tightly at its tip (like a micro-pledget).
   • Dip the cotton tip in trichloroacetic acid.
   • Apply precisely and lightly to the edges of the perforation rim only - circumferentially around the entire rim.
   • The acid whitens (denatures) the squamous epithelium immediately on contact.
   • Care is taken not to apply excess chemical, which could damage the middle ear mucosa.
4. Patching: After cauterisation, the perforation is covered with one of the following patch materials:
   • Gelfoam (absorbable gelatin sponge) - most commonly used
   • Gelfilm (gelatin film)
   • Cigarette-paper patch (a classic, inexpensive option)
   • Hyaluronic acid film (e.g., Epidisc - a modern alternative)
5. Post-procedure care:
   • Prescribe local antibiotic drops
   • Advise water precautions (keep ear dry)
   • Instruct the patient to avoid nose-blowing and sneezing with open mouth
6. Follow-up and repetition:
   • The procedure is repeated every 2 weeks until the perforation heals
   • Multiple sessions are usually required

Fat Plug Variant (for tiny perforations)

Outcomes

• Reported success rate: approximately 64% with the chemical cauterisation + patching technique
• Better results expected with smaller perforations, dry ears, and good Eustachian tube function
• Ongoing Eustachian tube dysfunction in the contralateral ear (e.g., OME, negative middle ear pressure) is a predictor of poor outcomes

Advantages of OPD Chemical Cauterisation

• No general anaesthesia required
• No hospitalisation
• Low cost
• Avoids surgical risks (SNHL, ossicular damage, facial nerve injury)
• Can be repeated until closure achieved
• Suitable for patients unfit for or refusing formal tympanoplasty

When to Abandon OPD Procedure and Proceed to Formal Tympanoplasty

• Large perforations (> 4 mm, or > 25-30% of TM area)
• Failure after multiple cauterisation sessions
• Marginal/posterior perforation
• Ossicular chain discontinuity or tympanosclerosis
• Cholesteatoma detected
• Persistent Eustachian tube dysfunction

• Shambaugh Surgery of the Ear, Office Chemical Myringoplasty section
• Cummings Otolaryngology Head and Neck Surgery, Minimalist Techniques (Tympanoplasty chapter)