What are the steps involved in a mastoidectomy procedure for a patient with mastoiditis or cholesteatoma?

Mastoidectomy Surgical Steps

Mastoidectomy is performed through a systematic approach involving cortical mastoidectomy, identification of key anatomical landmarks, disease removal, and reconstruction, with the specific technique (canal wall up vs. canal wall down) determined by disease extent and mastoid anatomy.

Preoperative Imaging Assessment

• Obtain high-resolution CT temporal bone without IV contrast to define anatomy, assess disease extent, and identify anatomical variations including ossicular chain integrity, facial canal dehiscence, tegmen erosion, lateral semicircular canal erosion, and scutum erosion 1.
• Add MRI head and internal auditory canal without and with IV contrast, specifically with nonechoplanar diffusion-weighted imaging (DWI) in the coronal plane, when cholesteatoma is suspected to differentiate it from granulation tissue and scar with high sensitivity and specificity 1.

Core Surgical Steps

Initial Exposure and Cortical Mastoidectomy

• Make a postauricular incision and elevate the periosteum to expose the mastoid cortex 2, 3.
• Perform cortical mastoidectomy by drilling through the outer cortical bone to enter the mastoid air cell system, identifying the antrum as the primary landmark 4, 3.
• Progressively remove diseased air cells while maintaining orientation to critical structures 4.

Identification of Anatomical Landmarks

• Identify the lateral semicircular canal as the primary landmark - this structure serves as the reference point for all subsequent dissection 1.
• Locate the tegmen mastoideum (roof of the mastoid) superiorly to avoid intracranial complications 1.
• Identify the sigmoid sinus posteriorly as the posterior boundary of dissection 2, 3.
• Trace the facial nerve course, noting any dehiscence identified on preoperative CT 1.

Disease Removal

• Remove all cholesteatoma matrix and diseased tissue completely - incomplete removal results in residual disease in 35% of staged procedures 5.
• Assess ossicular chain integrity and remove necrotic ossicles (particularly incus) as indicated 1.
• Examine the attic (epitympanum) for disease extension, performing atticotomy if cholesteatoma is limited to this region 3.

Canal Wall Decision Point

• Perform canal wall up (intact canal wall) mastoidectomy for limited disease in adequately pneumatized mastoids, planning for staged procedures in 92% of cases to address residual disease 5, 3.
• Convert to canal wall down mastoidectomy when disease extensively involves the epitympanum, extends to the facial recess, or occurs in sclerotic/poorly developed mastoids where adequate visualization cannot be achieved 2, 3, 6.
• Create a modified radical mastoid cavity with canal wall down technique by removing the posterior canal wall, lowering the facial ridge, and performing meatoplasty for adequate postoperative cavity care 6.

Reconstruction Phase

• Perform tympanoplasty with fascia graft for tympanic membrane reconstruction 5, 6.
• Reconstruct ossicular chain if feasible, using autograft or prosthesis as indicated 6.
• Stage the procedure in canal wall up cases, planning second-look surgery at 6-12 months to identify and remove residual cholesteatoma found in 35% of cases 5.

Critical Technical Considerations

• Maintain continuous suction-irrigation to clear bone dust and maintain visualization during drilling 4.
• Use diamond burrs near critical structures (facial nerve, lateral semicircular canal, sigmoid sinus) to minimize thermal and mechanical injury 4.
• Preserve the posterior canal wall whenever possible, as recurrence rates with intact canal wall technique are low (8%) and progression to canal wall down is required in only 4% of cases 5.

Common Pitfalls to Avoid

• Never assume complete disease removal without staging in canal wall up procedures - 35% harbor residual cholesteatoma at second-look surgery despite appearing complete at initial operation 5.
• Avoid inadequate exposure of the facial recess in canal wall up procedures, which leads to residual disease 3.
• Do not create excessively large mastoid cavities in canal wall down procedures, as this increases postoperative care requirements 6.
• Recognize that sclerotic or poorly pneumatized mastoids on preoperative imaging predict need for canal wall down approach 6.

Postoperative Management

• Plan second-stage surgery at 6-12 months for canal wall up procedures to address residual disease 5.
• Schedule regular cavity cleaning for canal wall down procedures, though properly performed modified radical cavities seldom cause long-term problems and do not preclude swimming 6.
• Monitor for recurrence with clinical examination and consider repeat imaging if symptoms recur, as 8% develop recurrent cholesteatoma requiring additional surgery 5.