Canal wall up procedure and canal down procedure

Reading File

Finding Sources

Reading File

Finding Sources

Reading File

I now have comprehensive data from multiple authoritative textbooks. Let me compile the full answer.

Canal Wall-Up (CWU) vs. Canal Wall-Down (CWD) Mastoidectomy

These are the two primary surgical strategies for managing chronic otitis media with cholesteatoma. The choice between them is one of the most debated decisions in otologic surgery.

Nomenclature

Both procedures are types of tympanomastoidectomy. Related techniques include:

Simple mastoidectomy
Canal wall-up (CWU) mastoidectomy - also called intact canal wall mastoidectomy, closed cavity, combined approach tympanoplasty
Canal wall-down (CWD) mastoidectomy - also called open cavity mastoidectomy
Radical mastoidectomy
Modified radical mastoidectomy (Bondy procedure)
Mastoid obliteration / Canal reconstruction mastoidectomy

(Cummings Otolaryngology, Box 143.2)

Canal Wall-Up (CWU) Mastoidectomy - "Closed" Technique

Definition

CWU mastoidectomy involves complete removal of mastoid air cells while maintaining the bony posterior external auditory canal (EAC) wall intact. The tympanic membrane and middle ear anatomy are preserved in near-normal configuration. The procedure typically includes a facial recess approach - drilling between the facial nerve, chorda tympani nerve, and incus buttress to access the middle ear from posteriorly.

Surgical Steps (Cummings, Box 143.3)

Expose and identify key surface landmarks of the mastoid bone
Remove cortical bone at the temporal line and just posterior to the external canal
Identify the position of the tegmen and sigmoid sinus
Exenterate mastoid air cells between these key anatomic structures
Thin the external auditory canal and remove bone from the zygomatic root area
Identify and open the mastoid antrum
Identify the short process of the incus and the dome of the lateral semicircular canal
Identify and skeletonize the mastoid segment of the facial nerve
Open the facial recess (area between the facial nerve, chorda tympani, and incus buttress)

Advantages

Physiologic position of the tympanic membrane maintained
Adequate middle ear space preserved - better hearing reconstruction potential
No mastoid cavity problem - no "bowl" to clean
More rapid healing
Better tolerance of water and environmental exposures
Hearing aid use is well tolerated
No meatoplasty required

Disadvantages

Higher recidivism rate: residual cholesteatoma 11-27%; recurrent cholesteatoma 5-13%
Incomplete exteriorization of facial recess - blind spots remain
Second-stage "second look" operation frequently required (typically at 9-12 months)
New retraction pockets can form behind the intact canal wall
Endoscopic-assisted CWU can reduce residual disease rate from ~47% to ~5.5% (Thomassin)

Canal Wall-Down (CWD) Mastoidectomy - "Open" Technique

Definition

CWD mastoidectomy involves thorough removal of mastoid air cells, complete removal of the superior and posterior canal walls, aggressive saucerization of cortical edges, and meatoplasty. This creates a single unified space (the "mastoid bowl") merging the external canal, mastoid, and middle ear. The tympanic membrane is usually reconstructed to create a pneumatized middle ear space.

Key Surgical Components

Thorough mastoid air cell exenteration
Complete removal of the posterior bony EAC wall
Aggressive saucerization / rounding of cortical edges
Lowering of the facial ridge (the bony shelf over the facial nerve) - essential step
Meatoplasty - widening of the external meatus to allow cavity ventilation and visualization

Subtypes

Subtype	Description
Modified radical mastoidectomy	CWD with preservation of tympanic membrane remnant and ossicular reconstruction; Eustachian tube kept open
Radical mastoidectomy	CWD + sacrifice of tympanic membrane and lateral ossicular chain + obliteration of Eustachian tube; reserved for extensive disease
Bondy procedure	CWD for pars flaccida/attic cholesteatoma with intact pars tensa; hearing mechanism preserved

Advantages

Lower recidivism rate: 6-20% (vs. 25-45% for CWU) - Cummings
Residual cholesteatoma easily identified on follow-up clinic examination
Recurrent cholesteatoma is rare
Total exteriorization of facial recess
Highest rate of success on initial (single-stage) surgery
Better visualization of mesotympanum and epitympanum intraoperatively

Disadvantages

Mastoid bowl problem - requires long-term, often lifelong, periodic aural toilet
May require years for full epithelialization
Middle ear is shallow and difficult to reconstruct
Position of pinna may be altered
Temperature-induced dizziness (caloric effect from water/air in open cavity)
Hearing aid fitting is complicated - moisture trapping and infection risk with occlusive molds
Second-stage operation sometimes still required
Self-cleaning ability of the EAC is lost

Reasons for a Persistently Draining Mastoid Cavity (KJ Lee)

Inadequate meatoplasty
Dependent tip cell
High facial ridge
Exposed Eustachian tube

Comparison Table

Feature	Canal Wall-Up (CWU)	Canal Wall-Down (CWD)
Canal wall preserved	Yes	No
Meatoplasty	Not required	Required
Residual cholesteatoma rate	11-27%	2-10%
Recurrent cholesteatoma rate	5-13%	Lower
Second look surgery	Usually required	Less often
Mastoid bowl	None	Present (lifelong care)
Hearing outcomes (long-term)	Similar	Similar
Hearing aid tolerance	Good	Problematic
Water exposure	Tolerated	Avoided / restricted
Surgical difficulty	More complex	Better disease exposure

Hearing results: Long-term studies including Toner and Smyth (mean 9 years follow-up) show no significant difference in hearing outcomes between the two procedures. - Scott-Brown's Otorhinolaryngology

Indications for CWD Over CWU (Cummings + KJ Lee)

Preoperative (Favor CWD)

Only-hearing ear - eradicate disease in one operation, avoid risk of second surgery
Poor anesthetic risk patient (single-stage preferred)
Unreliable for follow-up / second-look surveillance
Contracted (sclerotic) mastoid
Labyrinthine (horizontal semicircular canal) fistula
EAC erosion by cholesteatoma

Intraoperative (Favor CWD)

Low-lying tegmen limiting access
Anterior sigmoid sinus limiting access
HSCC fistula - may need to leave matrix over fistula and proceed open
Disease deeply infiltrating the sinus tympani or posterior recesses
Extensive disease not amenable to safe CWU removal

Mastoid Obliteration

A middle ground between pure CWU and CWD: the surgeon performs CWD but then obliterates the cavity with autologous materials (bone pâté, bone chips, cartilage, fat, musculoperiosteal flap) or biomaterials (hydroxyapatite). This combines the disease-clearance advantage of CWD with the functional benefit of no persistent bowl. In a systematic review of 13 studies and 1,534 patients, recurrent and residual cholesteatoma rates in obliterated cavities were 5.8% and 5.9%, respectively - Cummings Otolaryngology, p. 2746.

Summary

The choice between CWU and CWD remains surgeon- and patient-dependent. CWU preserves anatomy and avoids a bowl but carries a higher recurrence rate and usually mandates staged second-look surgery. CWD offers better disease control and single-stage eradication at the cost of a mastoid cavity requiring lifelong maintenance. Endoscopic-assisted CWU surgery is narrowing the recurrence gap. Canal reconstruction and obliteration techniques aim to combine the best of both approaches.

Sources: Cummings Otolaryngology Head and Neck Surgery (Ch. 140, 143) | Shambaugh Surgery of the Ear | Scott-Brown's Otorhinolaryngology Head & Neck Surgery Vol. 2 | KJ Lee's Essential Otolaryngology

This is a shared conversation. Sign in to Orris to start your own chat.