Canal wall Down VS Canal wall Up Mastoidectomy

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🦻 Mastoidectomy: Canal Wall Up vs Canal Wall Down

Key Anatomical Landmarks

Structure	Description	Clinical Importance
Aditus	Communication between middle ear and mastoid antrum	Surgical pathway
Posterior canal wall	Common wall between EAC (front) and mastoid antrum (back)	Decides CWU vs CWD
Spine of Henle	Bony projection in posterosuperior EAC	Surface landmark
McEwan's triangle (Suprameatal triangle)	Bounded by: supramastoid crest (superior), posterosuperior EAC line (anterior), tangent joining them (posterior)	Mastoid antrum ~1.5 cm deep
Facial bridge	Part of posterior bony canal wall overlying fossa incudis	Removed in Canal wall down surgery for exposure
Facial ridge	Posterior canal wall overlying bony facial canal	Lowered during surgery, cannot be removed fully (risk of Facial Nerve injury)
Anterior buttress	Junction of posterior canal wall with tegmen	Surgical landmark
Posterior buttress	Junction of posterior canal wall with EAC floor	Surgical landmark

Definition of Mastoidectomy

Term	Definition
Mastoidectomy	Surgical removal of mastoid air cells in temporal bone to eradicate disease & access middle ear cleft
Canal Wall Up (CWU)	Posterior canal wall preserved → mastoid cavity remains separate from EAC
Canal Wall Down (CWD)	Posterior canal wall removed → mastoid cavity + EAC become one large cavity

Goals

Procedure	Aim
Canal Wall Up (CWU)	Eradicate disease while preserving near-normal canal anatomy and hearing mechanism
Canal Wall Down (CWD)	Eradicate disease with wide exteriorization, ensuring a safe, dry ear

Common Surgeries

Canal Wall Up (CWU)	Canal Wall Down (CWD)
Cortical mastoidectomy (aka Simple/Schwartz/Complete Mastoidectomy)	Atticotomy
Combined approach tympanoplasty (CAT)	Atticoantrostomy
–	Modified radical mastoidectomy
–	Radical mastoidectomy

Indications

Canal Wall Up (CWU)	Canal Wall Down (CWD)
Limited cholesteatoma (attic/antrum only)	Extensive/recurrent cholesteatoma
Good Eustachian tube function	Posterior canal wall erosion
Reliable patient follow-up	Poor Eustachian tube function
Preferred first surgery (esp. children)	Unreliable follow-up
–	Complicated CSOM (intracranial/extracranial)
–	Revision surgeries

Exposure & Clearance

Canal Wall Up (CWU)	Canal Wall Down (CWD)
Limited exposure – sinus tympani, anterior epitympanum, hypotympanum difficult to visualize	Wide exposure – direct view of all recesses
Higher chance of residual disease	More complete clearance

Recurrence

Canal Wall Up (CWU)	Canal Wall Down (CWD)
Higher recurrence/residual disease (10–40%)	Lower recurrence (2–10%), easier detection

Hearing Outcomes

Canal Wall Up (CWU)	Canal Wall Down (CWD)
Better – normal canal acoustics, ossicular reconstruction easier	Poorer – large cavity, less favorable acoustics, though ossiculoplasty still possible

Postoperative Canal Appearance

Canal Wall Up (CWU)	Canal Wall Down (CWD)
Normal EAC preserved	Enlarged meatus with large mastoid cavity

Cavity Care & Follow-up

Canal Wall Up (CWU)	Canal Wall Down (CWD)
No cavity care required; ear is self-cleansing	Lifelong periodic cleaning (aural toileting)
Requires strict follow-up & second-look surgery (6–18 months)	Less stringent follow-up needed

Complications

Canal Wall Up (CWU)	Canal Wall Down (CWD)
Higher residual/recurrent disease, retraction pocket formation	Cavity-related problems: otorrhea, granulation tissue, meatal stenosis

Patient Limitations

Canal Wall Up (CWU)	Canal Wall Down (CWD)
No long-term restrictions; swimming allowed	Swimming/bathing restrictions (risk of infection, caloric vertigo)

Auditory Rehabilitation

Canal Wall Up (CWU)	Canal Wall Down (CWD)
Easier to fit hearing aids	Hearing aid fitting difficult due to large cavity/infections

Advantages vs Disadvantages

Canal Wall Up (CWU) Advantages	Canal Wall Up (CWU) Disadvantages
Preserves EAC anatomy	Limited exposure
Better hearing outcome	Higher recurrence (10–40%)
No cavity, no lifelong care	Requires second-look surgery
Fewer lifestyle restrictions	Retraction pocket risk if Eustachian Tube function poor
Preferred in children	–

Canal Wall Down (CWD) Advantages	Canal Wall Down (CWD) Disadvantages
Excellent exposure, complete clearance	Creates large cavity → cavity related issues
Lower recurrence (2–10%)	Lifelong cleaning needed
Recurrence easily visible	Water restrictions (no swimming)
No need for second look	Cosmetic deformity (enlarged meatus, postauricular hollow)
Useful in unreliable follow up	Worse hearing outcome, hearing aid fitting difficult

Types of Mastoidectomy (Quick Definitions)

Surgery	Type	Key Features
Cortical mastoidectomy	CWU	Exenteration of all accessible mastoid air cells; posterior canal wall intact; preserves TM & ossicles
Radical mastoidectomy	CWD	Removes mastoid + middle ear + attic + antrum; posterior canal wall removed; removes TM remnants, all ossicles except stapes footplate; ET opening closed
Modified radical mastoidectomy	CWD	Like radical but preserves TM remnants, functioning ossicles, and ET opening

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