What does MRM stand for in ear disease?

MRM in Ear Disease

MRM stands for Modified Radical Mastoidectomy, a canal wall down surgical procedure used to eradicate chronic middle ear and mastoid disease, particularly chronic suppurative otitis media with cholesteatoma. 1, 2

Surgical Technique and Goals

Modified Radical Mastoidectomy is a definitive surgical approach that removes the posterior and superior canal walls while preserving the tympanic membrane and middle ear structures when possible. 1 The primary objectives are:

• Complete eradication of disease (cholesteatoma, chronic infection, or mastoiditis) 2, 3
• Creation of a safe, stable, and self-cleaning mastoid cavity 3, 4
• Preservation or improvement of hearing when feasible 1, 2

The procedure differs from radical mastoidectomy in that MRM attempts to preserve middle ear structures and hearing function, whereas radical mastoidectomy removes the tympanic membrane and ossicles entirely. 1

Hearing Outcomes

MRM does not worsen hearing and can provide hearing improvement, particularly when combined with type III tympanoplasty. 2, 3 Key factors affecting hearing results include:

• The presence of an intact stapes superstructure is the major determinant of postoperative air-bone gap closure (p=0.025 preoperatively, p=0.031 postoperatively) 2
• Primary surgery yields better hearing outcomes than revision procedures 1
• Average hearing gain of 21.24 dB in air conduction and 15.62 dB closure of air-bone gap when combined with type III tympanoplasty 3
• No significant worsening of bone conduction thresholds despite extensive drilling 1

Approximately 53% of patients show no improvement in air-bone gap closure, while 25% demonstrate postoperative improvement. 2 However, the procedure consistently avoids creating "dead ears" or causing significant hearing deterioration. 1

Postoperative Course and Cavity Management

The majority of MRM cavities achieve a dry, self-cleaning state, but this requires variable periods of intensive aftercare. 4 The healing timeline follows this pattern:

• 36% of cavities are stable at 6 months 4
• 42% achieve stability at 1 year 4
• 53% are stable at 18 months 4
• 62% reach stability at 2 years 4
• Overall, 73-78% of patients ultimately achieve a dry ear 2, 4

Important caveat: Even after achieving initial stability, 23% of cavities require further clinical intervention, sometimes after prolonged quiescent periods. 4 This necessitates long-term follow-up, with patients making an average of 632 total visits beyond the two standard postoperative appointments. 4

Disease Control and Recurrence

MRM provides excellent disease control with only a 3% recurrence rate. 2 The procedure is particularly effective for:

• Chronic active otitis media with cholesteatoma 2, 3
• Chronic mastoiditis 2
• "End-stage" chronic otitis media with persistent infection despite prior treatment 5

For patients with retained infected residual cell tracts causing persistent disease, radical revision mastoidectomy (RRM) with exenteration of all residual cells and mastoid obliteration achieves an 80% dry ear rate. 5

Clinical Context and Patient Selection

MRM is particularly valuable in populations with limited access to follow-up care, as it provides maximum benefit in a single-stage procedure. 3 The technique offers:

• Reproducible and relatively safe surgical access 1
• No requirement for revision surgery in most cases 4
• Effective management of extensive disease in tertiary referral populations 1

Common pitfall: Inadequate removal of residual cell tracts or creation of a meatus that is too small are the most frequent causes of surgical failure. 5 Complete exenteration of all mastoid, middle ear cleft, perilabyrinthine, and peri-Eustachian tube cell tracts is essential for optimal outcomes. 5