Tympanic Membrane Perforation

TM Perforation: Anatomy & Intro - The Drum Breach

• Definition: A defect or hole in the tympanic membrane (TM), separating the external auditory canal from the middle ear.
• Anatomy of TM:
  • Layers (3): Outer squamous epithelium, middle fibrous (radial & circular fibers), inner mucosal. 📌 Mnemonic: Elephants Find Mice (Epithelial, Fibrous, Mucosal).
  • Parts: Pars Tensa (inferior, larger, taut, 3 layers, main vibratory part); Pars Flaccida (Shrapnell's membrane; superior, smaller, lax, 2 layers - lacks fibrous layer).
• Significance: Impairs sound conduction (hearing loss) & protection.

⭐ The absence of the middle fibrous layer in Pars Flaccida makes it more susceptible to retraction and the development of attic cholesteatoma.

TM Perforation: Etiology & Types - Why Drums Burst

• Etiology:
  • Traumatic:
    • Direct: Q-tip injury, foreign body, iatrogenic (e.g., syringing).
    • Indirect: Barotrauma (slap, blast, diving), temporal bone fracture.
  • Infective:
    • Acute Suppurative Otitis Media (ASOM): Pus bursts through TM.
    • Chronic Suppurative Otitis Media (CSOM): Persistent perforation.
• Types (Site):
  • Central (Tubotympanic): Pars tensa; TM remnant all around. Generally safer.
  • Marginal (Atticoantral): Involves annulus; cholesteatoma risk ↑.
  • Attic (Atticoantral): Pars flaccida; cholesteatoma risk ↑.

    ⭐ Marginal & Attic perforations are considered unsafe/dangerous due to high cholesteatoma risk.

• Types (Size): Small (<25%), medium (25-50%), large (>50%), subtotal.

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TM Perforation: Clinical Features - Hole Telltales

• Symptoms:
  • Hearing loss: Conductive, severity varies with size/location.
  • Otorrhea: If infected; mucoid, purulent, or blood-tinged.
  • Tinnitus: Whistling, especially with small perforations.
  • Otalgia: Usually brief, with acute injury or infection.
• Signs (Otoscopy):
  • Visible perforation: Central, marginal, or attic.
  • Loss of landmarks: Cone of light, handle of malleus may be visible through hole.
  • Middle ear mucosa: May be visible, normal or inflamed.

⭐ Rinne test negative (bone conduction > air conduction) in affected ear; Weber test lateralizes to affected ear (conductive hearing loss).

TM Perforation: Diagnosis - Spotting the Split

• Otoscopy:
  • Direct visualization of perforation (site, size, shape).
  • Margins: Acute (sharp edges), Chronic (rounded, epithelialized).
  • Middle ear mucosa may be visible.
• Tuning Fork Tests (512 Hz):
  • Rinne: Negative (BC > AC) in affected ear.
  • Weber: Lateralizes to affected ear.
• Audiometry:
  • Pure Tone Audiometry (PTA): Conductive Hearing Loss (CHL); degree varies with size/site.
  • Tympanometry: Type B curve (large ear canal volume).

⭐ In PTA, an air-bone gap > 15-20 dB is significant for CHL in TM perforation contexts.

TM Perforation: Management & Complications - Mending & Mayhem

Management Strategy:

• Conservative:
  • Keep ear dry (water precautions).
  • Antibiotic ear drops if signs of infection (e.g., ciprofloxacin).
  • Observation for spontaneous healing (common in traumatic perforations).
• Surgical (Myringoplasty):
  • Indications: Perforation persisting > 3-6 months, recurrent otorrhea, significant hearing loss.
  • Techniques: Underlay, Overlay (temporalis fascia commonest graft).

Potential Complications:

• Hearing Loss (Conductive/Mixed).
• Chronic Suppurative Otitis Media (CSOM) - persistent discharge.
• Cholesteatoma formation (especially marginal perforations).
• Tympanosclerosis.
• Recurrent infections.

⭐ Most traumatic TM perforations, especially small to moderate central ones, heal spontaneously within 6-8 weeks to 3 months. Water precautions are crucial during this period.

High‑Yield Points - ⚡ Biggest Takeaways

• Most common causes: Trauma (e.g., slap, Q-tip injury) and Acute Suppurative Otitis Media (ASOM).
• Most common site: Pars tensa, especially the anteroinferior quadrant.
• Key symptoms: Conductive hearing loss (CHL), tinnitus; otorrhea if infected.
• "Safe" vs. "Unsafe": Central perforations are generally safe; marginal and attic perforations are unsafe due to cholesteatoma risk.
• Healing: Small, dry traumatic perforations often heal spontaneously within weeks.
• Management: Keep ear dry; myringoplasty for persistent or symptomatic perforations.
• Blast injury: Often causes multiple perforations or subtotal/total loss of the tympanic membrane.