What are the steps of a canal wall down mastoidectomy with cavity obliteration in an elderly patient with chronic suppurative otitis media, bilateral complete hearing loss, diabetes, and cardiovascular disease, including intraoperative anatomy and postoperative management?

Canal Wall Down Mastoidectomy with Cavity Obliteration: Surgical Steps and Intraoperative Anatomy

For an elderly patient with chronic suppurative otitis media, bilateral complete hearing loss, diabetes, and cardiovascular disease, canal wall down mastoidectomy with cavity obliteration using autologous materials is the definitive surgical approach, with particular attention to atraumatic technique given the diabetes-related risk of necrotizing complications. 1, 2

Preoperative Considerations in High-Risk Patients

Critical risk stratification is mandatory before proceeding:

• Diabetic patients require special consideration due to susceptibility to necrotizing otitis externa and increased infection risk, necessitating optimized glycemic control preoperatively 3
• Avoid ear canal irrigation in diabetic or immunocompromised patients, as this has been implicated as a contributing factor to malignant otitis externa; use only atraumatic cleaning with aural suctioning under microscopic guidance 3
• CT imaging is essential to assess the extent of mastoid involvement and evaluate for potential intracranial complications before surgery 1
• Cardiovascular disease requires anesthesia optimization and perioperative cardiac risk assessment

Surgical Steps of Canal Wall Down Mastoidectomy with Obliteration

Step 1: Incision and Exposure

• Postauricular incision is made approximately 1 cm behind the postauricular crease, extending from the temporal line superiorly to the mastoid tip inferiorly 4
• Elevate anteriorly based musculoperiosteal flap for later use in obliteration 4
• Harvest autologous materials during initial exposure: temporalis fascia for tympanic membrane reconstruction, and musculoperiosteal flap with bone pâté for cavity obliteration 2, 4

Step 2: Mastoidectomy - Key Anatomic Landmarks

• Identify the temporal line (linea temporalis) superiorly - marks the level of the middle cranial fossa dura 5
• Locate the spine of Henle - marks the lateral semicircular canal position 5
• Expose the mastoid antrum by drilling through cortical bone, staying posterior to the spine of Henle 5
• Identify the lateral semicircular canal - critical landmark; injury causes severe vertigo (occurred in 1.5% of cases) 5
• Visualize the sigmoid sinus posteriorly - defines the posterior limit of dissection 5
• Identify the facial nerve in its vertical (mastoid) segment - runs anterior to the lateral semicircular canal; injury rate is 0.3% 5

Step 3: Canal Wall Removal

• Remove the posterior canal wall completely, creating communication between the external auditory canal and mastoid cavity 2, 5
• Lower the facial ridge to eliminate the overhang between the canal and cavity, preventing debris accumulation 4, 5
• Perform meatoplasty with horizontal skin incision on the concha to create adequate exposure and prevent stenosis 4

Step 4: Disease Removal

• Complete cholesteatoma removal is mandatory, inspecting all epitympanic recesses, facial recess, and sinus tympani 1, 2
• Remove all granulation tissue and infected mucosa 6
• In diabetic patients, ensure meticulous hemostasis and complete disease clearance to prevent postoperative infection 3

Step 5: Tympanic Membrane Reconstruction

• Cartilage reconstruction shows superior outcomes compared to temporalis fascia, with graft integration rates of 92.4% versus 84.3% 1
• Place scaffold material (gelatin sponge) to support the graft 1
• Reconstruct ossicular chain if hearing preservation is a goal (though this patient has bilateral complete hearing loss) 5

Step 6: Cavity Obliteration

• Use anteriorly based musculoperiosteal flap to line the cavity and reduce its size 4
• Fill residual cavity with autologous bone pâté collected during drilling, mixed with bone chips 2, 4
• Alternatively, use combinations of bone, cartilage, or fat grafts 7
• Obliteration prevents cavity problems including persistent discharge, need for lifelong aural toilet, and water precautions 2, 6

Step 7: Closure

• Close musculoperiosteal layer and skin in layers 4
• Place mastoid dressing 5

Postoperative Management in High-Risk Patients

Diabetic patients require enhanced surveillance:

• Systemic antibiotics covering Pseudomonas and MRSA should be used given diabetes and invasive infection risk 3, 1
• Monitor for signs of necrotizing otitis externa: persistent pain, granulation tissue at bony-cartilaginous junction, cranial nerve involvement 3
• Cavity epithelialization occurs in 11.1±4.6 weeks on average, with complete healing ranging from 4-24 weeks 4
• Follow-up visits average 10 times in first 6 months, then twice yearly for 6 years 5

Expected Outcomes

Success rates with obliteration technique:

• 83-95% achieve dry, self-cleaning cavity without need for lifelong maintenance 6, 4, 5
• No recurrent cholesteatoma in properly executed obliteration series during 64-month average follow-up 2
• Recurrent/residual cholesteatoma rate of 3-6.1% in non-obliterated or improperly obliterated cavities 4, 5
• Hearing improvement or stability in 72% of cases (though not the primary goal in this bilaterally deaf patient) 5

Critical Pitfalls to Avoid

In diabetic patients specifically:

• Never irrigate the ear canal - use only dry suction under microscopic visualization to prevent necrotizing otitis externa 3
• Maintain high suspicion for fungal superinfection (Aspergillus, Candida) which is more common in diabetics 3
• Watch for facial nerve paralysis as early sign of necrotizing extension 3

General surgical pitfalls:

• Incomplete cholesteatoma removal leads to recurrence; inspect all hidden areas including facial recess and sinus tympani 1, 2
• Inadequate meatoplasty causes stenosis and poor postoperative access 4
• Insufficient lowering of facial ridge creates debris trap 4, 5
• Retroauricular skin depression is common complication of obliteration technique but cosmetic only 2