Types of Tympanic Membrane Perforation

Anatomy Reminder

• Pars tensa — the large lower portion, attached to the bony EAC via the tympanic annular ligament
• Pars flaccida (Shrapnell's membrane) — the smaller, less rigid superior portion above the notch of Rivinus

Classification by Location

1. Central Perforation

• Located entirely within the pars tensa, with an intact annular rim of TM surrounding the defect
• Does not involve the annulus (the fibrocartilaginous ring)
• Most commonly results from acute otitis media or trauma
• Considered "safe" — lower risk of cholesteatoma
• Subdivided by quadrant: anterior, posterior, inferior, or subtotal/total

2. Marginal Perforation

• Reaches the annulus (involves the edge of the TM)
• Most commonly found in the posterosuperior quadrant
• Considered "unsafe" — significantly higher risk of cholesteatoma formation due to ingrowth of squamous epithelium from the canal
• Requires urgent ENT referral

3. Attic (Pars Flaccida) Perforation

• Involves the pars flaccida in the superior/attic region
• Classic site for primary acquired cholesteatoma
• Often presents as a retraction pocket filled with keratin debris

Classification by Etiology

Classification by Duration

The "Safe" vs "Unsafe" Distinction (Clinically Critical)

Classification by Size

• Small: < 25% of TM surface
• Medium: 25–50%
• Large: > 50%
• Subtotal: Near-total, with a small annular rim remaining
• Total: Complete destruction of the TM

Key Clinical Points

• Spontaneous rupture in AOM occurs in ~5% of cases; Nontypeable H. influenzae is the most common pathogen in children; heals in ~90% without intervention (K.J. Lee's Essential Otolaryngology)
• Perforations in the posterosuperior quadrant or after penetrating trauma carry greater risk of ossicular chain damage and warrant ENT referral within 24 hours (Tintinalli's)
• Marginal perforations involving the annulus are more likely to result in retained debris and cholesteatoma (Cummings Otolaryngology Head and Neck Surgery)
• Water precautions apply to all perforations until healed

Classification of Tympanic Membrane Perforation

I. By Location (Most Clinically Important)

A. Central Perforation

• Situated entirely within the pars tensa
• Annular rim is intact — the perforation does not reach the bony annulus
• The handle of the malleus may still be visible
• Associated with tubotympanic (safe) disease
• Sub-classified by quadrant:
  • Anteroinferior — most common in traumatic perforation (slap, barotrauma)
  • Posteroinferior — common in infective (AOM)
  • Posterosuperior — risk of ossicular chain damage; urgent ENT referral required
  • Kidney-shaped / reniform — horseshoe shape around malleus handle

B. Marginal Perforation

• Reaches the annulus — no intact rim at one or more edges
• Most commonly posterosuperior quadrant
• Associated with atticoantral (unsafe) disease
• High risk of cholesteatoma formation — squamous epithelium migrates through the annular gap
• Pockets and perforations marginal in location are more likely to result in retained debris and cholesteatoma — Cummings Otolaryngology

C. Attic (Pars Flaccida) Perforation

• Located in the pars flaccida (Shrapnell's membrane), superior to the notch of Rivinus
• Result of a retraction pocket that deepens into a primary acquired cholesteatoma
• Often appears as a crust or keratin debris plugging a superior defect
• Also called "attic perforation" — the most dangerous type
• Classified as unsafe / atticoantral disease

II. Safe vs. Unsafe — The Clinical Dichotomy

III. By Size

IV. By Aetiology

Traumatic perforations almost always occur in the pars tensa, typically anteriorly or inferiorly — Tintinalli's Emergency Medicine

V. By Duration

VI. By Disease Type (ENT Classification)