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

Learning Objectives

• Elicit and document a history in a patient with CSOM and correctly identify the mucosal (tubotympanic) type based on history and otoscopic features
• Distinguish mucosal (safe) CSOM from squamosal (unsafe) CSOM using the central vs marginal/attic perforation and the presence or absence of cholesteatoma
• Describe the clinical features, otoscopic findings, and investigations appropriate for mucosal CSOM
• Describe the indications for and steps involved in myringoplasty and tympanoplasty (Wullstein Types I–V) for mucosal CSOM

INSTRUCTIONS

Chronic suppurative otitis media (CSOM) is one of the most common ENT problems encountered in India and is a leading cause of preventable conductive hearing loss. The mucosal (tubotympanic) type — also called the 'safe' type — is the more common variant and is characterised by a central tympanic membrane perforation, mucosal middle ear disease, and absence of cholesteatoma. Understanding the safe/unsafe distinction is the most critical clinical skill in ENT practice: incorrectly classifying an unsafe CSOM as safe can delay lifesaving surgery. This module covers the safe type and its definitive surgical repair — myringoplasty and tympanoplasty.

References

• Dhingra PL — Diseases of Ear, Nose and Throat, 7th edition, Ch 6 (CSOM) (textbook)
• Hazarika P — Textbook of ENT and Head and Neck Surgery, 3rd edition, Ch 9-10 (textbook)
• Scott-Brown's Otorhinolaryngology, Head and Neck Surgery, 8th edition, Vol 2 (Otology) (textbook)

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Version 2.0 | NMC CBUC 2024

Clinical Presentation of Mucosal (Tubotympanic) CSOM

The clinical presentation of mucosal CSOM is dominated by two cardinal features: chronic or recurrent otorrhoea (ear discharge) and chronic conductive hearing loss. In contrast to ASOM, there is no fever and no severe otalgia — the absence of pain is one of the most clinically important features of uncomplicated mucosal CSOM and can be used to reassure patients that their disease is under control, while also serving as a red-flag indicator (onset of pain or headache in a previously painless CSOM suggests the development of a complication). The typical history follows a recognisable pattern: recurrent acute ear infections in childhood → initial episodes of ear discharge associated with fever → eventual resolution but incomplete TM healing → residual perforation → subsequent episodes of discharge triggered by URTIs or water entry into the ear without fever or severe pain. The discharge in mucosal CSOM is characteristically mucoid or mucopurulent, and — in uncomplicated disease — it is odourless or only mildly offensive. A frankly offensive, foul-smelling discharge with associated otalgia should immediately raise the suspicion of unsafe CSOM with cholesteatoma, where infected keratin debris produces a characteristic foul odour.

History of presenting illness — key questions:
- Duration of ear discharge (months to years), frequency (intermittent vs persistent), and triggers (URTIs, water entry)
- Character of discharge: colour, consistency (mucoid vs purulent vs thick cheesy), odour (odourless/mild = safe; offensive/foul = suspect unsafe)
- Hearing loss: gradual, bilateral or unilateral, worse on the affected side; duration
- Pain: ABSENT in uncomplicated mucosal CSOM; any new or worsening otalgia = red flag for complication or unsafe disease
- Tinnitus: present in some cases as a result of the conductive loss
- History of childhood ear infections, ASOM episodes, previous ear surgery
- Vertigo or facial weakness: both are red flags for complications regardless of type

Predisposing and perpetuating factors:
- Childhood recurrent ASOM (most common antecedent)
- Poverty, crowded living conditions, poor nutrition (affect immune response and access to care)
- Swimming (water entering through the perforation introduces pathogens)
- Delayed or inadequate antibiotic treatment of childhood ASOM

Anatomy and Pathophysiology of Mucosal CSOM

The pathophysiology of mucosal CSOM is best understood through the central principle of the safe vs unsafe distinction — the single most important conceptual divide in the management of chronic ear disease. Mucosal CSOM is called the 'safe' type not because it carries zero risk, but because in its uncomplicated form it does not erode bone, does not produce cholesteatoma, and carries a relatively low risk of intracranial complications. The squamosal (atticoantral, 'unsafe') type, by contrast, involves cholesteatoma, bone erosion, and high complication risk — it demands urgent surgical intervention and is covered in a separate module. Grasping this distinction at a deep anatomical level — not just as a label — is what allows the clinician to look at an otoscopic image and immediately classify the disease, choose the appropriate management pathway, and avoid the catastrophic error of treating unsafe CSOM conservatively while cholesteatoma silently erodes the ossicles, tegmen, or facial nerve canal.

The safe/unsafe distinction rests on two anatomical observations:

1. Location of the TM perforation:
- Mucosal (safe) type = central perforation in the pars tensa. A central perforation is one surrounded by a rim of residual TM on all sides — the annulus fibrosus is intact. The perforation may be small, medium, or large (subtotal), but healthy TM tissue remains as a border. Because the pars tensa forms the floor and walls of the mesotympanum, a central perforation exposes the mucosal middle ear but not the attic, the epitympanum, or the mastoid antrum — areas of dangerous communication where cholesteatoma forms.
- Squamosal (unsafe) type = attic or marginal perforation. An attic perforation is in the pars flaccida (Shrapnell's membrane) — the superior slacker portion of the TM. A marginal perforation extends to the annulus with no TM rim remaining at the edge. Both types allow squamous epithelium to migrate into the middle ear, forming a cholesteatoma — a destructive cyst of desquamating keratin-producing epithelium.

2. Disease process:
- Mucosal type: The middle ear mucosa is inflamed and oedematous, producing mucoid secretions. The ossicles are usually intact (though may be partially eroded in long-standing disease). No cholesteatoma is present. The pathological process is confined to the mucosa of the mesotympanum and Eustachian tube.
- Squamosal type: Cholesteatoma is present — keratin-filled squamous epithelium expands in the middle ear, secreting collagenases that erode bone (ossicles, tegmen, labyrinthine bone, facial nerve canal) and eventually breach the skull base or dura.

Why perforations in ASOM fail to heal: After ASOM, the TM heals by re-epithelialisation from the edges of the perforation. In some cases — particularly after repeated infections, large perforations, or perforations involving the posterior quadrant where the blood supply is poorer — healing fails. The Eustachian tube dysfunction that caused the ASOM persists, creating chronic negative middle ear pressure that prevents natural healing. The residual perforation then becomes a route for recurrent contamination.

Tympanic Membrane Perforations: Safe vs Unsafe Types

Examination and Investigations in Mucosal CSOM

The examination in mucosal CSOM begins with a thorough otoscopic assessment and hearing evaluation, supplemented by investigations to quantify hearing loss, assess ossicular integrity, and evaluate Eustachian tube function before planning surgery. The goal of examination is twofold: confirm the safe mucosal type (by excluding cholesteatoma, attic perforation, and marginal perforation) and assess the surgical candidacy of the patient (hearing level, ear status, ET function). This dual purpose shapes the examination sequence: the first part is diagnostic (is this safe or unsafe?) and the second is pre-operative (is this patient ready for tympanoplasty?). Every otoscopic examination of a CSOM ear must include explicit inspection of the pars flaccida — the failure to examine this superior quadrant is the single most common reason an attic perforation is missed and an unsafe CSOM is incorrectly classified as safe.

Otoscopic examination — systematic approach:
Clean the external auditory canal of discharge and wax with gentle suction or wicking. Then examine the TM systematically:
- Perforation location and size: Confirm it is a central perforation in the pars tensa; estimate size as small (<25% of TM), medium (25–50%), large (50–75%), or subtotal (>75%). The pars flaccida must be specifically examined — if it appears retracted, thickened, or has any defect, the classification must be reconsidered
- Pars flaccida: Must be intact and visible; any crust, retraction pocket, or perforation in the pars flaccida suggests unsafe type
- Middle ear mucosa: Visible through the perforation — in mucosal CSOM it appears pale pink or red and oedematous; mucoid secretion may be present; NO whitish pearly debris, no granulations eroding bone
- Ossicles: The handle of malleus and the umbo are identifiable from the perforation margin; note whether the incus long process or stapes is visible (their absence may indicate erosion)
- Retraction pockets: Should be specifically looked for in all quadrants; a deep retraction pocket in the posterosuperior quadrant can hide early cholesteatoma

Hearing assessment:
- Tuning fork tests (512 Hz): Rinne negative on the affected side (BC > AC) confirming conductive hearing loss; Weber lateralises to the affected ear; ABC (absolute bone conduction) test — if normal (same as examiner's), ossicular chain and cochlear function are intact. A reduced ABC suggests sensorineural component or mixed loss.
- Pure-tone audiometry (PTA): Shows conductive hearing loss with an air-bone gap; the size of the gap correlates roughly with perforation size and ossicular integrity. A purely conductive air-bone gap of 20–40 dB with normal bone conduction thresholds is characteristic of uncomplicated mucosal CSOM. If the bone conduction threshold is elevated, suspect inner ear involvement (labyrinthine or toxic damage from chronic infection)

Investigations:
- CT of the temporal bone (HRCT): Not routine for uncomplicated mucosal CSOM, but indicated when: (1) ossicular erosion suspected, (2) need to plan the extent of surgery, (3) complication suspected. HRCT is MANDATORY in squamosal/unsafe CSOM — but for straightforward mucosal CSOM, otoscopy + PTA are often sufficient for surgical planning
- Eustachian tube function tests: Critical before tympanoplasty. A simple test: the patient performs the Valsalva manoeuvre and the surgeon observes air bubbling through the middle ear (via the perforation). Eustachian tube patency is necessary for surgical success — grafting a TM onto a middle ear with severely dysfunctional ET leads to early graft failure and recurrence of retraction
- Culture and sensitivity: Of discharge when present; guides choice of topical antibiotic