Tympanomastoid Surgery: Incisions and Endoscopic Approaches

PART 1 - Types of Incisions Used in Tympanomastoid Surgery

1. Transcanal (Meatal) Incision

• The patient's head is turned away
• Incisions are placed in the posterior and/or inferior canal skin
• The meatal flap is elevated medially to expose the tympanic membrane and posterior tympanicum
• No skin incision is made outside the ear

• Tympanoplasty for posterior perforations
• Stapedectomy (anteriorly based tympanomeatal flap)
• Ventilating tube insertion
• Ossiculoplasty for posterior/inferior ossicular pathology
• Excision of small glomus tympanicum tumors visible at otoscopy
• Myringotomy

2. Endaural Incision

1. Circumferential (canal) segment - runs circumferentially inside the canal
2. Intercartilaginous segment - passes between the helical crus and the tragus (the "Lempert notch")
3. Vertical (temporal) limb - extends superiorly toward the temporal region

Endaural incision showing the three segments: (1) circumferential canal portion (white dashes), (2) intercartilaginous limb (green), and (3) vertical temporal limb (red dashes). Image: Stanford Oto Surgery Atlas / Jackler & Gralapp.

• The circumferential incision is carried at the bony-cartilaginous junction of the EAC
• The incision is extended superiorly through the intercartilaginous cleft between the helical crus and tragus
• The vertical limb extends up to expose temporalis fascia
• Needle-point electrocautery is used through the dermis to reach the temporalis fascia superiorly
• The temporalis muscle is elevated off the linea temporalis
• This gives access to the superior canal, epitympanum, and (with the Heermann extension) the mastoid

Commencing the postauricular/endaural skin incision with scalpel. Image: Stanford Oto Surgery Atlas / Jackler & Gralapp.

• Canalplasty (for exostoses, stenosis)
• Tympanoplasty - especially for anterior perforations and total drum replacement
• Anterior atticotomy
• When the postauricular approach risks collapsing the ear canal (the auricle migrates anteriorly with postauricular incisions)
• Procedures in an abnormally narrow meatus
• As an alternative to postauricular incision for limited mastoidectomy

• Scar is hidden within the conchal bowl / intercartilaginous area (cosmetically superior to postauricular in some patients)
• No risk of anterior ear canal collapse postoperatively
• Good access to the anterior EAC and epitympanum
• Temporalis fascia graft is readily accessible

• Visible scar in the concha in some patients
• Limited posterior exposure compared to the postauricular approach
• Not ideal when wide mastoidectomy is anticipated

3. Postauricular (Retroauricular) Incision

• The pinna tilts ~15 degrees posteriorly relative to the axis of the malleus/TM
• The incision is made 5-10 mm behind the postauricular sulcus (heal better, less retraction than sulcus incisions)
• The superior limb is carried forward to allow the ear to rotate anteriorly for full middle ear access
• Inferiorly, the incision is carried to the mastoid tip (in infants, take care - no developed mastoid tip, facial nerve at risk)
• Skin and subcutaneous tissue are incised through to periosteum
• The linea temporalis is identified - the bony ridge forming the inferior margin of the temporalis muscle fossa (a key surgical landmark)
• Electrocautery opens the periosteum along the linea temporalis, extending forward to the anterior aspect of the EAC so soft tissues rotate forward
• A periosteal elevator (e.g., Lempert) exposes the mastoid cortex
• The SCM insertion is dissected off the mastoid tip
• Two retractors are placed: one spanning ear canal to sinodural angle, one lifting temporalis muscle

Soft-tissue layers in cross-section at the linea temporalis during postauricular approach: skin and dermis, areolar tissue, temporalis fascia, temporalis muscle, periosteum, and bone. Image: Stanford Oto Surgery Atlas / Jackler & Gralapp.

Completed postauricular exposure with retractors showing access to the ear canal, tympanic membrane, and mastoid cortex. Image: Stanford Oto Surgery Atlas / Jackler & Gralapp.

• Tympanoplasty (all types, especially anterior perforations requiring wider access)
• Tympanomastoidectomy (canal wall up or down)
• Hypotympanotomy
• Cochlear implantation (modified postauricular)
• Ossiculoplasty
• Facial nerve decompression
• Access to mastoid for revision surgery

• Widest exposure of the tympanomastoid compartment
• Excellent access for temporalis fascia harvest through the same incision
• Standard approach for all mastoid surgery

• Scar behind the ear (usually well-hidden)
• Risk of anterior migration of the auricle postoperatively (can cause ear canal collapse)
• Greater tissue dissection than endaural or transcanal approaches

3a. Modified Postauricular Incision

3b. Extended Postauricular Incision

• Tympanomastoid compartment
• Upper neck structures
• Infratemporal fossa

Summary Table of Incisions

PART 2 - Types of Endoscopic Tympanomastoid Surgery

A. Classification of Endoscopic Ear Surgery (TEES Classification System)

Type 1 - Exclusive (Purely Endoscopic, Transcanal)

• Used for: Myringoplasty, tympanoplasty (limited perforations), stapedectomy, ossiculoplasty, attic cholesteatoma limited to epitympanum, exploration of middle ear recesses (sinus tympani, facial recess)
• The endoscope replaces the microscope entirely
• Single hand holds the endoscope; the other hand works instruments

Type 2 - Endoscope-Assisted (Combined Endoscopic + Microscopic)

• Used for: Combined approach tympanoplasty for cholesteatoma, second-look procedures after microscopic canal wall up mastoidectomy, identification of residual disease in the sinus tympani or facial recess
• Particularly valuable for inspecting the posterior mesotympanum through the facial recess
• Reduces the residual/recurrent cholesteatoma rate by identifying disease invisible to the angled microscope

Type 3 - Extended Endoscopic (Endoscopic with External Approach)

• Used for: Large cholesteatomas with extensive mastoid involvement, cases requiring canal wall down or open mastoidectomy, endoscopic open tympanoplasty for attic and antral cholesteatoma in sclerotic mastoids
• The mastoid is drilled from behind (postauricular), and the endoscope is used trancanally for the tympanic/epitympanic components

B. Specific Endoscopic Tympanomastoid Procedures

1. Endoscopic Tympanoplasty (Myringoplasty)

• Performed entirely transcanally with the endoscope
• The graft (cartilage, temporalis fascia via separate small incision above the ear, or fat) is placed under/over the TM
• Closure rates comparable to microscopic approach (endoscopic: ~85%, microscopic: ~86.4%)
• Advantage: no postauricular incision, shorter operating time, lower morbidity

2. Endoscopic Atticotomy

• Transcanal removal of the scutum to expose the lateral epitympanum
• Piezosurgery or chisel used to remove the lateral attic wall
• Indicated for attic cholesteatomas
• The attic is reconstructed with cartilage at the end

3. Endoscopic Canal Wall Up Tympanomastoidectomy (with or without microscope)

• The lateral attic wall is removed trancanally with the endoscope (atticotomy)
• If mastoid involvement is limited, the entire procedure can be endoscopic
• Endoscope provides unparalleled views of the facial recess, sinus tympani, and retrotympanum - areas notorious for residual cholesteatoma after microscopic surgery
• Facial recess can be drilled and inspected endoscopically without posterior tympanotomy

4. Endoscopic Canal Wall Down (Open) Tympanoplasty

• Introduced for sclerotic mastoid or attic cholesteatoma with antral extension
• The endoscopic "open" technique provides a wide atticotomy to expose and exteriorize the antrum, left open toward the EAC (analogous to classical CWD)
• Avoids postauricular incision in select cases with sclerotic mastoid

5. Endoscopic Second-Look Mastoidoscopy

• After primary microscopic canal wall up mastoidectomy for cholesteatoma
• Endoscope introduced trancanally (or through the mastoid cavity) ~12 months postoperatively
• Inspects for residual disease in the mastoid antrum, epitympanum, sinus tympani, and facial recess
• McKennan (1993) first described this as "endoscopic second look mastoidoscopy"

6. Endoscopic Stapedectomy / Stapedotomy

• Fully transcanal, no external incision
• The endoscope provides a wider field of view of the oval window niche than the monocular microscope
• Comparable outcomes to microscopic stapedotomy

7. Endoscopic Sinus Tympani and Retrotympanum Exploration

• The sinus tympani (posterior recess behind the facial nerve) is notoriously invisible to the operating microscope
• The sinus tympani has been classified into three types based on depth:
  • Type A: Shallow - fully explorable endoscopically
  • Type B: Deep - explorable endoscopically
  • Type C: Deep with posterior extension behind the facial nerve - NOT fully accessible even endoscopically
• The endoscope (30° or 45° angled) allows direct visualization and removal of cholesteatoma from this recess

8. Endoscopic Transpromontorial Approach (Lateral Skull Base)

• Most advanced application of TEES
• The entire cochlea and vestibule are drilled through the external canal and middle ear after ossicular removal
• Provides access to the internal auditory canal (IAC) for acoustic neuroma removal
• Preserves the posterior fossa dura approach entirely from the transcanal route

C. Advantages of Endoscopic Over Microscopic Tympanomastoid Surgery

D. Limitations of TEES

• One hand always holds the endoscope (one-handed dissection)
• Loss of stereoscopic (binocular) depth perception
• Heat from the endoscope tip (irrigation needed to prevent inner ear thermal injury)
• Blood and secretions obscure the lens
• Cannot fully access Type C sinus tympani (deep, behind facial nerve)
• Extensive mastoid disease still requires combined or postauricular approach (Type 3 TEES or conventional mastoidectomy)

References

• Stanford Oto Surgery Atlas (Jackler & Gralapp) - Endaural and Postauricular Incision chapters
• Entokey: "Incisions and Approaches" - Chapter 9
• PMC 11546356: Villari D et al. "Endoscopic Ear Surgery, from the Last Ten to the Next Ten Years: A Critical Perspective" (2024)
• K.J. Lee's Essential Otolaryngology - Endoscopic tympanoplasty outcomes
• Scott-Brown's Otorhinolaryngology - Surgical approaches for paediatric cholesteatoma; minimally invasive second-look CAT