Mastoidectomy

Definition

Mastoidectomy is a surgical procedure involving the removal of the mastoid cortex and air cell system of the temporal bone. It forms the cornerstone of otologic surgery and is used to manage disease processes ranging from chronic suppurative otitis media and cholesteatoma to cochlear implantation and skull base tumors.

Cummings Otolaryngology Head and Neck Surgery, p. 2741

Surgical Anatomy

The mastoid bone is the posterior part of the temporal bone. Key surface landmarks include:

Right temporal bone lateral view showing the temporal line, zygomatic process, mastoid process, mastoid foramen, tympanomastoid fissure, external acoustic meatus, and styloid process

Fig. 143.1 Right temporal bone, lateral view - Cummings Otolaryngology

Critical surgical landmarks during mastoidectomy:

Temporal line - approximates the floor of the middle cranial fossa (tegmen)
Sigmoid sinus - posterior limit of dissection
Mastoid antrum - key landmark connecting to the middle ear via the aditus ad antrum
Short process of the incus and dome of the lateral semicircular canal - the "pointer" to the facial nerve
Facial nerve (mastoid segment) - runs from the second genu downward through the stylomastoid foramen; must be identified and protected
Digastric ridge - inferior landmark for the descending facial nerve
Facial recess - bounded laterally by the chorda tympani, medially by the facial nerve, superiorly by the fossa incudis

Indications (Box 143.1)

Category	Examples
Chronic ear disease	Chronic otitis media, cholesteatoma
Acute infection	Acute suppurative mastoiditis, subperiosteal abscess, coalescent mastoiditis
Facial nerve	Idiopathic (Bell's palsy) or traumatic facial nerve palsy
Vestibular	Meniere's disease (endolymphatic sac decompression), BPPV (posterior canal occlusion), superior canal dehiscence syndrome, vestibular neurectomy
Skull base	Cerebellopontine angle tumors, petrous apex cholesterol granuloma
CSF leak	Spontaneous CSF leak, encephaloceles
Implants	Cochlear implantation, auditory brainstem implant (translabyrinthine)
Malignancy	Temporal bone / parotid malignancy resection

Nomenclature

The terminology for mastoid surgery is notoriously confusing. The standard procedures are:

Procedure	Key Feature
Simple mastoidectomy	Removes cortex + limited air cells; used for acute mastoiditis drainage
Canal wall-up (CWU) / intact canal mastoidectomy	Complete air cell exenteration while preserving the bony EAC wall
Canal wall-down (CWD) mastoidectomy	Removes superior and posterior canal walls; creates an open mastoid bowl
Radical mastoidectomy	CWD + removal of tympanic membrane, ossicles, and posterior EAC wall; no attempt at hearing preservation
Modified radical (Bondy) mastoidectomy	Epitympanic cholesteatoma exteriorized; uninvolved middle ear left intact; matrix maintained as cavity lining
Mastoid obliteration	Mastoid cavity filled with autogenous or alloplastic material
Canal reconstruction mastoidectomy	Temporary removal of bony EAC, then reconstruction after disease clearance
Retrograde mastoidectomy	Disease approached from the tympanum working posteriorly into the mastoid

Cummings Otolaryngology, Box 143.2, p. 2742

Surgical Technique (Canal Wall-Up)

Steps (Box 143.3)

Incision: C-shaped postauricular incision ~1 cm behind the postauricular crease; inject 1% lidocaine with 1:100,000 epinephrine
Exposure: Two periosteal incisions (along temporal line + perpendicular to mastoid tip) to fully expose the mastoid cortex
First burr cuts: Along the temporal line and tangential to the EAC posteriorly
Antrum identification: Remove mastoid cortex to identify the antrum (largest mastoid air cell, directly posterior to the EAC)
Key landmark identification: Tegmen (superiorly), sigmoid sinus (posteriorly)
Exenteration: Remove all mastoid air cells between these boundaries
Thinning the canal wall: Thin the posterior and superior EAC walls to improve visualization
Identify incus and lateral SCC: The short process of the incus and dome of the lateral semicircular canal are consistent "pointers" to the facial nerve
Facial nerve skeletonization: The mastoid segment is identified running from the second genu to the stylomastoid foramen
Facial recess opening (posterior tympanotomy): The triangle bounded by chorda tympani (laterally), facial nerve (medially), and fossa incudis (superiorly) is opened - provides access to the round window, promontory, IS joint, eustachian tube orifice
Epitympanum opening: Required for cholesteatoma tracking to the ossicular heads/supratubal recess; requires removal of incus remnant/malleus head if eroded

Note: Continuous facial nerve monitoring is standard for CWU mastoidectomy and all subsequent complex procedures.

Canal Wall-Down Mastoidectomy

Involves thorough removal of all mastoid air cells + aggressive saucerization of cortical edges + complete removal of the superior and posterior canal walls + meatoplasty. The tympanic membrane is usually reconstructed. This creates an open "mastoid bowl" that is continuous with the EAC.

CWU vs CWD: Comparative Considerations

Feature	Canal Wall-Up	Canal Wall-Down
Anatomy preserved	Yes	No
Residual cholesteatoma rate	Higher (~42% pediatric)	Lower (~12% pediatric)
Postop monitoring of disease	Requires second-look surgery	Direct visualization in clinic
Healing time	Faster	Slower (months of epithelialization)
Water exposure tolerance	Good	Problematic
Hearing aid use	Well tolerated	Increased infection risk
Long-term bowl maintenance	Not needed	May need regular debridements
Hearing outcomes	Similar	Similar

Indications for CWD over CWU:

Only-hearing ear (single surgery preferred)
Poor anesthetic risk
Unreliable follow-up
Low-lying tegmen + anterior sigmoid sinus (small cavity limits access)
Horizontal SCC (HSCC) fistula with extensive bone erosion
Deep sinus tympani (inaccessible via facial recess alone)

Cummings Otolaryngology, p. 2745-2746

Variant Techniques

Modified Radical (Bondy) Mastoidectomy

Specifically for cholesteatoma limited to the epitympanum. The superior/posterior canal wall over the epitympanum is removed to exteriorize the disease. The middle ear proper is not entered, and the cholesteatoma matrix is preserved as a lining. Unlike retrograde mastoidectomy, the canal and tympanic membrane defects are not repaired.

Mastoid Obliteration

Various materials used: autogenous bone/cartilage, free or vascularized soft tissue, bioactive glass (S53P4 - subject of a 2026 meta-analysis), or other alloplastic materials. Used as primary procedure or at second-look surgery.

Canal Reconstruction Mastoidectomy

Developed by Gantz et al. The bony EAC wall is temporarily removed using microsagittal saw cuts, disease is cleared, and the canal wall is then replaced in its native position (with mitered locking cuts). Cortical bone chips block the epitympanum and facial recess. The mastoid is then obliterated with bone pate. Benefits: CWD-level exposure during surgery + canal wall-up benefits postoperatively (no bowl, water tolerance).

Retrograde Mastoidectomy

Approaches cholesteatoma from the tympanum working posteriorly. Described by Dornhoffer as involving temporary upper canal wall removal followed by reconstruction.

Endoscopic-Assisted Mastoidectomy

Rigid endoscopes (including 45-degree scopes) provide visualization of recesses (sinus tympani, facial recess, anterior epitympanum) inaccessible to the straight microscope. However, endoscopy does not reduce cholesteatoma recidivism rates following primary surgery.

Complications

Complication	Notes
Facial nerve injury	Most feared; continuous intraoperative monitoring is standard
Hearing loss (sensorineural)	Drill heat/vibration transmitted to inner ear; irrigation and diamond burrs near ossicles
Perilymph fistula / labyrinthine fistula	Semicircular canal erosion by cholesteatoma; managed by keeping matrix intact over fistula in some cases
Sigmoid sinus injury	Venous bleeding; controlled with Surgicel/pressure
Dural breach / CSF leak	Middle cranial fossa or posterior fossa dura
Chorda tympani injury	Taste disturbance, dry mouth
Meningitis	Rare but serious
Residual / recurrent cholesteatoma	Leading cause of surgical failure
Mastoid bowl problems	Chronic discharge, granulations, water intolerance (CWD cavities)

Key Historical Notes

Ambrose Pare (16th century): Proposed drainage for King Charles II (operation refused; king died)
Jean Petit (late 1700s): First successful mastoid trephination
Sir William Wilde (1853): First postauricular incision
Schwartz & Eysell (1873): Reintroduced cortical mastoidectomy for acute infections
Zaufal (1890): Described the radical mastoidectomy (removal of TM, ossicles, posterior canal wall)
Bondy (early 1900s): Modified radical procedure preserving the middle ear

Shambaugh Surgery of the Ear, p. 1772-1786

Sources

Cummings Otolaryngology Head and Neck Surgery, Ch. 143, pp. 2741-2749
Shambaugh Surgery of the Ear, Ch. on Mastoid Surgery, pp. 1751-1790
Scott-Brown's Otorhinolaryngology Head & Neck Surgery Vol. 2, Ch. 103

Recent literature note: A 2026 systematic review and meta-analysis (PMID 41940705) evaluated mastoid obliteration using S53P4 bioactive glass granules - this represents an active area of current research into obliteration materials for canal-down cavities.

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