Mastoidectomy

On this page

Mastoid Anatomy & Basics - Bone Deep Dive

  • Temporal Bone Parts: Squamous, Mastoid (air cells), Petrosal (inner ear).
  • Mastoid Air Cells: Develop by age 5-6 years; types: pneumatic (well-aerated), diploic (marrow spaces), sclerotic (dense bone).
  • Surgical Landmarks (Surface):
    • Macewen's Triangle (suprameatal): Key to locating mastoid antrum.
    • Henle's Spine (suprameatal spine): Anterior border of Macewen's.
    • Temporal Line: Approximate level of middle cranial fossa floor.
  • Key Deep Structures:
    • Aditus ad antrum: Communication between epitympanum & mastoid antrum.
    • Mastoid Antrum: Largest, most constant air cell.
    • Facial Nerve (CN VII): Runs in fallopian canal.
    • Sigmoid Sinus: Major dural venous sinus.

Surgical anatomy of mastoid bone

⭐ Körner's septum (petrosquamosal lamina): A persistent embryological bony plate. If present, it can divide the mastoid into superficial squamous and deep petrosal cells, potentially leading to incomplete surgery if not identified and traversed. Its presence may limit access to deeper cells during mastoidectomy for cholesteatoma removal, increasing recurrence risk if missed.

  • Mastoidectomy: Surgical procedure to exenterate mastoid air cells. Purpose: eradicate infection/disease (e.g., cholesteatoma, mastoiditis), improve aeration, access middle ear.

Indications & Types - Why & How We Cut

Indications for Mastoidectomy:

  • Cholesteatoma: Primary.
  • Complicated Otitis Media (OM):
    • Acute Coalescent Mastoiditis (ACM)
    • Chronic Mastoiditis (refractory)
    • Abscess (e.g., Bezold's)
    • Facial palsy, labyrinthitis, intracranial.
  • Tumors: e.g., Glomus.
  • Access: Cochlear implant, labyrinthectomy.

⭐ Most common indication: CSOM with cholesteatoma.

Types: Main difference: posterior EAC wall management (Canal Wall Up/Down).

Canal Wall Up vs Down Mastoidectomy

FeatureSimple/CorticalCWUCWD
Post. WallIntactIntactRemoved
GoalMastoid cells clearanceDisease removal, preserve anatomyComplete disease removal, exteriorize
Middle EarUntouchedPathology removedCleared/exteriorized
HearingPreservedPreserved/reconstructableVariable, may ↓
IndicationsACMLimited cholesteatoma, good ETExtensive cholesteatoma, complications, poor ET
Cavity IssuesNoLess commonMore common (care needed)

📌 CWD: Wall Down = Wider exposure, Worse cavity, Wins vs recurrence.

Procedure Highlights - The Driller's Guide

  • Initial Cut: Postauricular (Wilde's).
  • Exposure: Elevate periosteum, expose mastoid cortex.
  • Drilling:
    • Start: Macewen’s triangle (suprameatal).
    • Technique: Saucerization (wide exterior, tapering deeper).
    • Burrs: Large cutting (e.g., 4-6mm) → smaller diamond (e.g., 1-2mm) near vital structures.
  • Landmarks (The "SAFE" Guide): 📌
    • Sigmoid Sinus plate (posteriorly).
    • Antrum, via Lateral Semicircular Canal (LSSC) (medially).
    • Facial Nerve (inferior to LSSC; use digastric ridge, cog as guides).
    • En Dural plate / Tegmen mastoideum (superiorly).
  • Irrigation/Suction: Constant; prevents thermal injury, clears field.

Mastoidectomy surgical landmarks and facial nerve

⭐ Donaldson's line (a line projected posteriorly from the horizontal semicircular canal) is a crucial landmark; the facial nerve lies inferior to it. The digastric ridge also reliably leads to the stylomastoid foramen area where the facial nerve exits.

Complications & Post-op - Healing & Hazards

  • Intra-operative Complications:
    • Facial Nerve (FN) injury: High risk at tympanic segment & second genu. Intra-op monitoring advised.
    • Sigmoid sinus bleeding: Control with pressure, packing (e.g., Surgicel).
    • Dural exposure/Cerebrospinal Fluid (CSF) leak: Repair with temporalis fascia/muscle graft, fibrin glue.
    • Ossicular chain damage → Conductive Hearing Loss (CHL).
    • Labyrinthine injury → Sensorineural Hearing Loss (SNHL), vertigo.
  • Post-operative Complications:
    • Wound infection, hematoma, pinna perichondritis.
    • Persistent SNHL, vertigo.
    • Taste disturbance (Chorda tympani injury) - usually transient.
    • Recurrence of cholesteatoma/disease.
  • Healing & Cavity Care (for open cavities):
    • Regular aural toilet (debridement) is crucial.
    • Meatoplasty often performed to improve aeration & self-cleaning.
    • Hazards: Chronic discharge, granulations, fungal infections (otomycosis), difficult-to-clean "sump" cavity.
    • Long-term follow-up with otoscopy, audiometry, and sometimes imaging.

Mastoidectomy anatomy with facial nerve and sigmoid sinus

⭐ The most common site of iatrogenic facial nerve injury during mastoidectomy is the tympanic segment, particularly near the oval window and cochleariform process, followed by the second genu (mastoid segment).

High‑Yield Points - ⚡ Biggest Takeaways

  • Mastoidectomy is primarily for cholesteatoma and complicated acute mastoiditis.
  • Canal Wall Down (CWD) procedures (e.g., Modified Radical, Radical) exteriorize disease, unlike Canal Wall Up (CWU).
  • Radical Mastoidectomy removes posterior meatal wall, malleus, incus, and tympanic membrane remnant.
  • Facial nerve injury (especially tympanic & mastoid segments) is a major risk.
  • Meatoplasty is essential for CWD cavity aeration and self-cleaning.
  • Bondy's operation is a CWD for attic cholesteatoma with intact pars tensa and ossicles, preserving hearing function where possible.

Practice Questions: Mastoidectomy

Test your understanding with these related questions

Nerve most commonly damaged in radical mastoidectomy is -

1 of 5

Flashcards: Mastoidectomy

1/10

_____ is used for removal of bony septa and granulations in mastoid surgery.

TAP TO REVEAL ANSWER

_____ is used for removal of bony septa and granulations in mastoid surgery.

Lempert s curette (scoop) (Instrument)

browseSpaceflip

Enjoying this lesson?

Get full access to all lessons, practice questions, and more.

Start Your Free Trial