Page 8 of 23

EN4.{6,10} | Mucosal CSOM with Myringotomy and Tympanoplasty — SDL Guide (Part 2)

Diagnosis and Differential Diagnosis

The diagnosis of mucosal CSOM is primarily clinical, combining a characteristic history (chronic recurrent odourless discharge, conductive hearing loss, no pain) with otoscopic confirmation of a central TM perforation in the pars tensa without cholesteatoma or attic involvement. The most important diagnostic distinction — and the one with the greatest clinical consequence — is between the mucosal (safe) and squamosal (unsafe) types of CSOM. This is not merely an academic categorisation: the unsafe type requires surgical intervention (mastoidectomy) regardless of symptoms, while the safe type can be managed conservatively until surgical conditions are optimal. The clinician who can make this distinction rapidly and reliably at the otoscope, without needing advanced imaging, is demonstrating the core ENT clinical competency that underlies all further management of chronic ear disease.

Safe vs Unsafe CSOM — the defining comparison:

Feature	Mucosal CSOM (Safe, Tubotympanic)	Squamosal CSOM (Unsafe, Atticoantral)
Perforation site	Central, pars tensa	Attic (pars flaccida) or marginal
Annulus involvement	No — TM rim present on all sides	Yes — marginal type has no TM rim
Cholesteatoma	ABSENT	PRESENT
Discharge	Mucoid/mucopurulent, odourless/mildly offensive	Scanty, foul-smelling (keratin + secondary infection)
Hearing loss	Conductive only (usually)	Conductive ± sensorineural if labyrinth eroded
Bone erosion	Absent or minimal	Significant — ossicles, tegmen, labyrinthine capsule, facial canal
Complications	Rare in uncomplicated disease	Common — mastoiditis, labyrinthitis, meningitis, brain abscess
Surgery urgency	Elective (tympanoplasty when ear is dry)	URGENT mastoidectomy regardless of symptoms

Additional differentials:

ASOM with spontaneous perforation: Acute onset (days, not months/years); fever and severe otalgia precede discharge; discharge purulent; TM hyperaemic around the perforation; perforation usually heals within 2–4 weeks with treatment. The chronicity of CSOM (>12 weeks by definition) distinguishes it.

Tympanosclerosis: White chalky calcification visible in the TM or on the ossicles — residual from old ASOM or previous ear surgery. TM is intact (no active perforation). Tympanosclerosis of the ossicles can cause conductive loss without perforation.

Otitis externa: Infection of the external canal, not the middle ear; TM usually normal when visible; tragal tenderness; history of water exposure or scratching.

Management: Medical and Surgical (Myringotomy and Tympanoplasty)

Management of mucosal CSOM has two phases: a conservative phase aimed at achieving a dry, infection-free ear, and a surgical phase (tympanoplasty) aimed at definitive repair of the TM perforation and restoration of hearing. The principle is that surgery should never be performed on a wet, actively infected ear — hence the conservative phase must precede surgery and the ear must be dry for a minimum of 6 weeks before tympanoplasty. Trying to graft an infected, discharging ear leads to graft failure and recurrence. This sequencing principle is one of the most operationally important rules in CSOM management. The reason it matters so much is pathological: in an actively infected middle ear, the mucosal surface cannot support the fascia graft, the operative field is obscured, and the graft is exposed to proteolytic enzymes from the infection that prevent fibroblast ingrowth and neovascularisation — the two processes on which graft take depends.

Provided image

Conservative management (to achieve a dry ear):
- Aural toilet: Dry mopping of the ear using a soft wick or suction to remove discharge; this is the single most effective conservative measure and should be performed at each clinic visit and taught to the patient for home care
- Topical antibiotic ear drops: Ciprofloxacin 0.3% ear drops (safe for use in perforated TM) are first-line; avoid aminoglycoside drops (gentamicin, neomycin) in perforated TM — ototoxic when they enter the middle ear through the perforation
- Systemic antibiotics: Used when active discharge with systemic signs (fever, cellulitis) is present; oral amoxicillin-clavulanate or ciprofloxacin based on culture; not indicated for routine management of chronic mucosal CSOM without active infection
- Treatment of Eustachian tube dysfunction: Intranasal corticosteroids and decongestants to reduce ET orifice mucosal oedema; treat allergic rhinitis; adenoidectomy if adenoid hypertrophy is a contributing factor
- Water precautions: Cotton wool with Vaseline in the ear during bathing; avoid swimming until TM is repaired

Surgical management — Tympanoplasty:

Wullstein Classification of Tympanoplasty (Types I–V):

Type	Procedure	Mechanism	Indication
I	Myringoplasty — TM repair only; ossicles intact	Restores intact TM over functioning ossicular chain	TM perforation with intact mobile ossicular chain (most common)
II	TM graft placed on incus head	Bridging erosion of malleus handle	Malleus eroded but incus present
III	TM graft placed directly on stapes head (columella effect)	Stapes-to-TM transmission	Malleus and incus both eroded; stapes intact and mobile
IV	TM graft placed over stapes footplate; oval window baffle	Round window protected from direct sound by graft position	Stapes superstructure eroded; footplate mobile
V	Fenestration of horizontal semicircular canal	Bypass via new fenestra	Fixed stapes footplate (otosclerosis) — rarely used now

Myringoplasty (Tympanoplasty Type I) — Operative Steps:
1. Pre-operative assessment: confirm dry ear for ≥6 weeks; PTA to confirm conductive loss; assess ET function; consent for the procedure
2. Anaesthesia: general anaesthesia (or local in cooperative adults)
3. Approach: post-aural (Wilde's incision behind the ear, most common) or endaural incision
4. Harvest graft: temporalis fascia is the most commonly used graft material — thin, durable, avascular (non-reactive), easy to harvest; alternative grafts: tragal cartilage perichondrium (more rigid, useful for large perforations or revision surgery), fat plug (for small anterior perforations)
5. Freshen the perforation edges: remove the epithelial edge of the perforation (the epidermal layer) using a round knife or micro-forceps to create a raw rim that will bond with the graft
6. Elevate a TM flap (tympanomeatal flap): elevate the posterior TM edge from the canal wall to access the middle ear and inspect the ossicular chain
7. Inspect the middle ear and ossicular chain: confirm ossicular mobility; remove any mucosal disease; assess ET orifice
8. Place the graft: the fascia graft is placed in the underlay position (deep to the TM remnant) — the graft lies between the TM and the middle ear, supported by Gelfoam packing placed in the middle ear space to hold the graft in position during healing
9. Re-drape the TM remnant over the graft; pack the canal with Gelfoam
10. Close the post-aural wound in layers; pack the outer canal with BIPP ribbon gauze
11. Post-operative: antibiotic cover; ear pack removal at 2–3 weeks; assess graft uptake at 6 weeks; PTA at 3 months to assess hearing gain

Self-Assessment: Mucosal CSOM and Tympanoplasty

Before attempting the final self-check question, ensure you can fluently articulate the following framework. The single most important concept in this module is the safe/unsafe distinction: mucosal CSOM is safe because it has a central pars tensa perforation without cholesteatoma; squamosal CSOM is unsafe because it has an attic or marginal perforation with cholesteatoma, bone erosion, and high complication risk. Conflating these two types — or failing to examine the pars flaccida and attic systematically — is the most serious clinical error in CSOM management. The management algorithm for mucosal CSOM follows a logical sequence: achieve a dry ear by conservative means (aural toilet, safe topical drops, treat ET dysfunction), confirm ear is dry for ≥6 weeks, then perform tympanoplasty. Tympanoplasty is classified by Wullstein's five types according to the ossicular status — Type I (myringoplasty, most common) repairs only the TM when ossicles are intact; higher types reconstruct progressively greater ossicular defects. Graft material of choice is temporalis fascia, placed in the underlay position. Hearing improvement is assessed by PTA at 3 months post-operatively.

Key consolidation checklist:
- Safe type = tubotympanic = mucosal = central perforation in pars tensa
- Unsafe type = atticoantral = squamosal = attic/marginal perforation + cholesteatoma
- Most common causative organisms in mucosal CSOM discharge: Pseudomonas aeruginosa, Staphylococcus aureus, Proteus mirabilis (often polymicrobial)
- Safe topical ear drops in perforated TM: ciprofloxacin; aminoglycosides (gentamicin) are CONTRAINDICATED
- Minimum dry ear duration before tympanoplasty: 6 weeks
- Wullstein Type I = myringoplasty (TM repair only)
- Graft of choice: temporalis fascia; placed underlay