Tympanoplasty, Tympanoplasty, Mastoidectomy, Facial Mastoidectomy, Facial Nerve DecompressionNerve Decompression

Hau Sin WongHau Sin Wong

Grand RoundsGrand Rounds

10/27/0410/27/04

TympanoplastyTympanoplasty

Definition: operation involving tympanic Definition: operation involving tympanic membrane and evaluation of middle earmembrane and evaluation of middle ear

Whereas myringoplasty is an operation of Whereas myringoplasty is an operation of the tympanic membranethe tympanic membrane

Tympanoplasty can be accompanied with Tympanoplasty can be accompanied with or without mastoidectomyor without mastoidectomy

Types of TympanoplastyTypes of Tympanoplasty

Type I: restoration of Type I: restoration of normal ME with intact normal ME with intact ossiclesossicles

Type II: Ossicular Type II: Ossicular chain partially chain partially destroyed but destroyed but preserved ad preserved ad continuity restoredcontinuity restored

Type III: TM lays on Type III: TM lays on stapes suprastructurestapes suprastructure

Type IV: Round window Type IV: Round window protection with a small protection with a small middle ear mobile middle ear mobile footplate left exposedfootplate left exposed

Type V: Closed middle Type V: Closed middle ear with round window ear with round window protection; fenestra in the protection; fenestra in the horizontal semicircular horizontal semicircular canal coveredby a skin canal coveredby a skin graft.graft.

Middle Ear AnatomyMiddle Ear Anatomy

Ossicles: Malleus, Incus, StapesOssicles: Malleus, Incus, Stapes

Ligaments: sup malleolar ligament, Ligaments: sup malleolar ligament, stapedial tendonstapedial tendon

Cochlearform process, pyramidal processCochlearform process, pyramidal process

TechniqueTechnique

1.1. Evaluate TM and ME if perforation presentEvaluate TM and ME if perforation present2.2. Create vascular stripCreate vascular strip3.3. Incise postauricular incision for mastoidectomyIncise postauricular incision for mastoidectomy4.4. Mastoidectomy- identify lateral landmarks for drilling. Anterior Mastoidectomy- identify lateral landmarks for drilling. Anterior

boundary-post EAC, superior boundary- root of the zygoma, linea boundary-post EAC, superior boundary- root of the zygoma, linea temporalis, inferior boundary- mastoid tip. Drill medially and temporalis, inferior boundary- mastoid tip. Drill medially and saucerize, delineating Tegmen superiorly, thinning post EAC saucerize, delineating Tegmen superiorly, thinning post EAC anteriorly, Sigmoid sinus posteriorly, Horizontal SCC mediallyanteriorly, Sigmoid sinus posteriorly, Horizontal SCC medially

5.5. Identify vertical segment of facial nerve between HSCC and Identify vertical segment of facial nerve between HSCC and digastric ridgedigastric ridge

6.6. Open facial recess: boundaries are fossa incudus, facial nerve, Open facial recess: boundaries are fossa incudus, facial nerve, chorda tympanichorda tympani

7.7. Visualization of incus, malleus in antrum, incus and stapes in Visualization of incus, malleus in antrum, incus and stapes in facial recess.facial recess.

Tympanomeatal flapTympanomeatal flap

EAC skin and TM EAC skin and TM elevated anteriorlyelevated anteriorly

TM grafts:TM grafts:

1. Cartilage 2. fool’s 1. Cartilage 2. fool’s fascia (loose areolar fascia (loose areolar fascia over temporalis fascia over temporalis fascia) 3. temporalis fascia) 3. temporalis fasciafascia

Medial or lateral graft Medial or lateral graft placementplacement

Facial Nerve Facial Nerve DecompressionDecompression

AnatomyAnatomy

5 segments 5 segments 1.1. Meatal- brainstem to IACMeatal- brainstem to IAC2.2. Labyrinthine- fundus of IAC to facial hiatus Labyrinthine- fundus of IAC to facial hiatus

(includes fallopian canal-narrowest segment of (includes fallopian canal-narrowest segment of facial canal)facial canal)

3.3. Tympanic- geniculate gangilion to pyraminal Tympanic- geniculate gangilion to pyraminal eminenceeminence

4.4. Mastoid-pyramidal eminence to stylomastoid Mastoid-pyramidal eminence to stylomastoid foramenforamen

5.5. Extratemporal- stylomastoid foramen to muscles Extratemporal- stylomastoid foramen to muscles of facial expression ( temporal, zygomatic, of facial expression ( temporal, zygomatic, buccal, mandibular, cervical)buccal, mandibular, cervical)

AnatomyAnatomy

Arterial Supply: Arterial Supply: 1.1. Intracranial segment supplied by Intracranial segment supplied by

labyrinthine artery off the AICAlabyrinthine artery off the AICA2.2. Tympanic segment supplied by Tympanic segment supplied by

superficial petrosal artery off the middle superficial petrosal artery off the middle meningeal arterymeningeal artery

3.3. Mastoid segment supplied by the Mastoid segment supplied by the stylomastoid artery off the external stylomastoid artery off the external carotid arterycarotid artery

Facial Nerve DecompressionFacial Nerve Decompression

Eggshell the facial canal (vertical Eggshell the facial canal (vertical segment)segment)Open Facial recess and extended the Open Facial recess and extended the facial recess using a barber pole methodfacial recess using a barber pole methodFollow facial nerve to the tympanic Follow facial nerve to the tympanic segmentsegmentEggshell covering overlying facial nerved Eggshell covering overlying facial nerved removed, exposing the sheathremoved, exposing the sheathSheath incised and facial nerve Sheath incised and facial nerve decompressed. decompressed.