Michael Castillo, MD

The history of ear surgery begins in the pre-antibiotic era with “barber surgeons” who performed I&D for coalescent mastoiditis.

The following is a succinct timeline for the history of ear surgery:

1671 - Riolanus describes opening the mastoid for infection

1774 - first successful mastoidectomy to evacuate pus by Petit in Paris

1791 - Baron Johann von Berger, Danish court physician, dies from meningitis following mastoid surgery for deafness

1853 - William Wilde (Father of Oscar Wilde) describes postauricular incision

1873 - Schwartz - publishes systematic account of simple mastoidectomy and its indications

1878-1899 - Kessel, Boucheron, Miot and others begin stapes mobilization procedures

1889 - Radical mastoidectomy described by Kuster

1905 - Modified radical mastoidectomy described by Health, Bryant and Bondy

1930’s - Lempert performs horizontal canal fenestrations for otosclerosis

1952 - Rosen serendipitously mobilizes a stapes while attempting horizontal canal fenestration

1956 - Shea introduces stapedectomy procedure as done today

Middle ear anatomy

The temporal bone is made up of the following bones: squamous, Mastoid, Tympanic, Petrous and Styloid.

The malleus is composed of the head, neck, anterior process, lateral (short) process and manubrium.  The incus is composed of the body, short process, long process and lenticular process. The stapes is composed of the head (capitulum), anterior crus, posterior crus and footplate.  The muscles of the middle ear include the stapedius and the tensor tympani.  The stapedius is innervated by CN VII, exits into middle ear at pyramidal eminence and functions by displacing the anterior border of footplate laterally (Dampens movement).  The tensor tympani is innervated by CN V.  Its medial fibers insert into cochleariform process and it then inserts into the medial and anterior surfaces of neck and manubrium of malleus.  It functions by displacing the manubrium medially (Decreases compliance of TM).

The following are the spaces of the middle ear:

Epitympanum

Superior to anterior and posterior mallear folds

Contains malleus head, incus body, ligaments and mucosal folds

Mesotympanum

Medial to pars tensa

Contains stapes, long process incus, handle of malleus

Hypotympanum

Inferior to level of inferior tympanic annulus

Protympanum

Anterior to anterior margin of tympanic annulus

Posterior mesotympanum

Posterior to posterior margin of tympanic annulus

Includes sinus tympani and facial recess

Supratubal recess

Anterior epitympanic recess

Partitioned from protympanum by mucosal fold at level of tensor tympani

The most common locations for cholesteatoma are:

Posterior epitympanum

Posterior mesotympanum

Anterior epitympanum

Facial nerve anatomy

The facial nerve is made up of the following segments:

Pontine

24 mm From origin to IAC

Meatal (IAC)

8 mm

Labyrinthine

4 mm

GSPN branches here

Narrowest segment of fallopian canal

Tympanic

12 mm

From geniculate ganglion to second genu

Most common area of dehiscence

Mastoid

15 mm

From second genu to stylomastoid foramen

Extratemporal

From stylomastoid foramen to muscles of innervation

Tympanoplasty

Tympanoplasty refers to a surgical procedure to reconstruct sound transmission mechanism of the middle ear, which includes myringoplasty, ossiculoplasty, canalplasty. Typically myringoplasty refers to reconstructions of TM without entering the middle ear.  Objectives of tympanoplasty include:

Eradication of disease

Restoration of tympanic aeration

Reconstruction of sound-transformer mechanism

Create dry, self-cleansing cavity

Tympanoplasty can be classified as follows as first described by Wullstein:

I - TM grafted to an intact ossicular chain

II - TM grafted to incus

III - TM grafted to stapes superstructure

IV - TM grafted to mobile footplate

V - TM grafted to fenestration in horizontal canal

Surgical approaches for tympanoplasty include transcanal, endaural and postauricular.  Typically postauricular approaches give the best visualization of the anterior extent of the TM. The two main types of grafting are underlay (medial) grafting and Overlay (lateral).

According to Rizer, there is a 95.6% drum closure in overlay versus 88.8% with underlay.  However, it was determined that both methods were fairly equivalent with no difference in complication or hearing results.

Tympanoplasty complications include the following:

Reperforation - most commonly after underlay repair of anterior pars tensa.

Epithelial inclusion cysts - most common after overlay technique with epithelial remnants left between original TM and fascial graft.

Blunting - due to inadequate bony sulcus or graft slipping from position.  May cause up to 10 to 15 dB hearing loss.

Lateralization - When overlay graft is not secured to malleus handle or too much packing placed in middle ear.  May cause up to 50 dB hearing loss.

Ossicular chain reconstruction (OCR)

Indications for OCR include:

Ossicular erosion from chronic otitis media

Ossicular removal due to cholesteatoma or tumor

Ossicular fractures or discontinuity from trauma

Lateral fixation of ossicular chain

Tympanosclerotic fixation of stapes and lateral chain

Contraindications include:

Residual cholesteatoma

Poor ET function

TM perforation with chronic draining ear

Acute infection

Materials for reconstruction include:

Natural

Autografts and homografts

Bone and cartilage

Synthetic (allografts)

Plastipore (High density polyethylene sponge)

Hydroxyapatite (HA)

Hybrids (Heads of HA, shafts of variety of materials)

Titanium

Bone cement

According to Goldberg and Emmet, a 1999 survey found 64% of otologists prefer HA or plastipore versus 25% preferring sculpting bone.  In contrast, the same authors sent a survey in 1989 which found bone to be the most preferred material.

Synthetics are used in three main scenarios:

PORP - intact stapes capitulum to malleus or TM

TORP - between stapes footplate to malleus or TM

Incus interposition - connects stapes capitulum to eroded incus long process

Failures of OCR are most commonly due to: Recurrent disease, poor aeration of ME, prosthesis slippage, inadequate prosthetic length

Mastoidectomy

The following are important terms to understand with mastoidectomy:

Simple mastoidectomy

removal of mastoid cortex and portion of underlying air cells /- entrering antrum; used for coalescent mastoiditis with subperiosteal abscess

Complete mastoidectomy - (intact canal wall procedure)

removal of air cells lateral to facial nerve and otic capsule bone while preserving canal walls for access to epitympanum

Can be combined with facial recess dissection to better expose posterior mesotympanum around oval and round windows and can be extended for access to hypotympanum and epitympanum

Modified radical mastoidectomy - (canal wall down procedure)

Indicated for disease in only hearing ear, poor follow-up patients, history of multiple failed attempts at CWU surgery, large posterior canal wall defects, labyrinthine fistula where matrix cannot be resected, obstructing low-lying middle fossa dura limiting access to epitympanum

Radical mastoidectomy

Exteriorized mastoid and middle ear without any reconstruction

Eustachian tube is occluded and ossicles removed

The surgical procedure for mastoidectomy follows important landmarks.  Begin by drilling along the linea temporalis, perpendicular to EAC and from mastoid tip to sinodural angle.  Keep posterior wall of EAC thin, once past Korner’s septum, the lateral SCC is visible.  Laterally it is important to skeletonize the middle fossa dural plate and follow this medially.  Open the zygomatic root by thinning superior EAC.  The epitympanum is the opened widely and malleus and incus visualized.  Skeletonize middle and posteior fossa plates, sigmoid sinus, posterior EAC wall, bony labyrinth.

The facial recess is an inverted triangle bounded by facial nerve posteriomedially, chorda tympani anterolaterally, and incus butress superiorly.  When dissecting in this area, use a large burr and copius irrigation.  It is possible then to extend the facial recess by removing incus butress, incus and head of malleus and sacrificing the chorda tympani nerve.

When performing a canal wall down mastoidectomy, it is important to eliminate bony overhangs and irregularities, remove posterior canal wall to level of capitulum and create a large meatus.  In performing a meatoplasty, remove 30% - 40% of conchal cartilage.  The meatoplasty will contract around 25%, so a good approximation is size of surgeon’s thumb.

The overall complication rate of mastoid surgery is around 1%-3%.  Injuries include, facial nerve injuries, vascular injuries, tegmen injuries and canal dehiscence.

Facial nerve injuries occur in less than 1% of first time ear surgeries, but in up to 4%-10% in revision cases.  Anatomic knowledge and systematic, landmark based surgery are keys to preventing injury. If an injury is discovered in the OR, several options are available.  If there is minimal nerve exposure or minor contusion, nothing needs to be done.  With extensive contusions it is advisable to decompress 5 - 10 mm on either side of dehiscence.  With a partial/complete transection, consider consultation to assist with decision-making.  If less than 1/3rd of the nerve is injured,  decompress either side of injury.  If more than 1/3rd is injured, perform either primary repair if there is no tension or use a nerve graft.  Patient and family must be extensively counseled to understand long term prognosis.  When discovered in the recovery room, begin by removing packing and if local anesthetic was used allow it to wear off (3-12 hours).  Consider re-exploration within 24-72 hours.

Tegmen injuries with only dural exposure typically require no repair.  When there is dural violation, remove bone around site and place a fascia/muscle plug

Stapes surgery

Patient selection for stapes surgery should include a conductive hearing loss >20 dB and negative Rinne test (BC > AC).  It is also necessary to rule out other causes of hearing loss (tympanosclerosis, middle ear effusion, TM perforation, cholesteatoma).  Consider stapes surgery in far-advanced otosclerosis as well as it may improve air-conduction thresholds by more than 20 dB and may improve hearing aid use with successful stapes operation.

Contraindications to stapes surgery include:

Associated endolymphatic hydrops

Only hearing ear

History of severe eustachian tube dysfunction or cholesteatoma

TM perforations (tympanoplasty first)

Small fenestra surgery (stapedotomy) involves the creation of a perforation through the footplate with pick, drill, or laser; then placing a piston prosthesis into vestibule.

Large fenestra surgery (stapedectomy) involves removal of total or posterior half of stapes and placing tissue graft and prosthesis.  Multiple studies have compared the two techniques.  Most recent studies conclude that in the hands of an experienced surgeon either technique is satisfactory.  Regardless of technique 90% of patients should have conductive deficit of <10 dB and <1% should have SNHL.  There is a decline in benefit over time after surgery around 0.6 to 1.2 dB per year (possibly presbycusis plus cochlear otosclerosis).

During stapes surgery a standard tympanomeatal flap is raised.  Elevate annulus and remove bone over scutum, taking care not to injure chorda tympani or disarticulate the incus.  The goal is to have facial nerve and pyramidal eminance clearly visualized.  The facial nerve is dehiscent in up to 50% of patients in this area.  Next, palpate ossicles to identify any lateral chain abnormalities then disarticulate IS joint with angled joint knife.  Cut the stapedial tendon with middle ear scissors. The stapes superstructure is then fractured downwards.  For stapedectomy, a control is hole placed along midportion of footplate, which can then be removed, either partially or whole footplate.  Do not suction over oval window.  Tragal perichondrium is then draped over the oval window and the prosthesis is placed.  For stapedotomy, use a footplate perforator to dilate to diameter needed for prosthesis to fit.  The diameter of perforation should not exceed the diameter of piston by more than 0.1 mm.

Specific techniques (laser, drill, micropicks) have consistent results in experienced surgeons.  Laser options include KTP, argon and CO2.  Laser may have a shorter learning curve (40-50 cases).  Studies have not shown significant increase in temperature within the vestibule with laser use.

Facial nerve anomalies such as an overhanging facial nerve, bifid facial nerve and facial nerve over promonitory are due to failure of Reichert’s cartilage to make contact with lateral wall of otic capsule.  Absence of a normal stapes superstructure allows facial nerve to develop at the level or below the level of the oval window.  Options include stopping the procedure or displacing the facial nerve and proceeding. 

A persistent stapedial artery is rare (1:5000-1:10000). Its course is from the internal carotid to the middle ear in hypotympanum anteriorinferiorly, appears to arise from promonitory, passes adjacent to stapes, travels with the facial nerve and then superiorly into an intracranial dural branch which substitutes for the middle meningeal artery.  By removing stapes superstructure enough room can be created to fenestrate stapes footplate and proceed.

Complications of stapes surgery includes:

Prosthesis displacement

accounts for 50% - 70% of revision surgeries

May occur years following surgery with hearing deterioration

Incus necrosis may occur due to loss of blood supply or overtightening of prosthesis

Oval window fistula

May occur early or late

Fluctuating or progressive hearing loss with tinnitus and vertigo

ENoG or ECoG may be helpful but not diagnostic

Clinical suspicion - exploration with grafting over oval window

Reparative granuloma

Occurs in 1%-2% of patients

Typically within 7 - 15 days but can be seen up to 6 weeks postoperatively

Thickened TM, posterior aspect erythemitous

Causes progressive SNHL and vertigo - indications for exploration

Delayed facial nerve paralysis

Typically 5 - 10 days postop and associated with pain

Steroids are treatment of choice

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