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ENT
Primary Surgery for Otosclerosis
Built from Haynes-Glasscock-Shambaugh Surgery of the Ear, Seventh Edition
What’s inside
11 sections · 156 slides
Overview
- Otosclerosis: pathology, etiology, epidemiology History of stapes and fenestration surgery Diagnosis: tuning forks, audiometry, imaging Indications, consent and anaesthesia Stapedotomy technique step by step Intraoperative and postoperative complications
The disease
- Primary bony dysplasia of the endochondral otic capsule First recognised by Politzer Irregular woven bone, unlike surrounding otic capsule One of the commonest causes of hearing loss Autosomal dominant, penetrance 20-40%
- Active phase: otospongiotic Many osteoblasts, numerous fibrovascular spaces Quiescent phase: otosclerotic Fibrovascular spaces fill with lamellar bone Both phases may coexist in one focus
- Most foci stay small and asymptomatic In 10-12%, focus encroaches on annular ligament Footplate involvement fixes the stapes Result: slowly progressive conductive hearing loss Termed stapedial otosclerosis
- Focus extends into the cochlear endosteum Produces concomitant sensorineural hearing loss Severity of the SNHL varies widely SNHL in 20-30% of otosclerosis patients Usually progressive
- Commonest in Caucasians Less common in Southeast Asians, Native Americans Rare in patients of African descent Histologic prevalence 8.3-12% in Caucasians About 1% in patients of African descent
- Histologic prevalence similar in both sexes Women 1.4-2x more likely to be clinically affected Clinical disease bilateral in about 75% 85-90% chance the other ear becomes involved Often asymmetric between the two ears
- Sequence of otosclerotic bone remodelling
- Other bones turn over about 10% per year Normal otic capsule: no more than 2% Otosclerosis = abnormal remodelling of this layer Confined to the endochondral layer Explains why the capsule is normally inert
- Anterior footplate focus fixes stapes in 96% Other areas involved in 49% of cases Round window niche 30%, cochlear apex 12% Round window niche obliterated in 7% Membranous labyrinth invasion is rare
- Early: bone encroaches on the anterior footplate Posterior footplate subluxes; low-frequency loss Late: lesion crosses stapediovestibular joint Bony fixation of the footplate Loss then affects all frequencies
- Mature focus: white, well-demarcated lesion Otic capsule around it is ivory coloured Active spongiotic lesion is richly vascular Hyperaemic mucosa over the promontory Seen through the drum as Schwartze's sign
- RANK-L expressed by osteoblasts RANK-L activates RANK on osteoclasts Drives osteoclast differentiation and survival Osteoprotegerin (OPG) competitively inhibits RANK-L High OPG suppresses remodelling
- Spiral ligament fibroblasts a probable source Found in high concentration in perilymph May spread through perilymphatic canaliculi Could explain the very slow otic capsule turnover Loss of this brake may permit otosclerosis
- Ten loci identified, designated OTSC1 to OTSC10 Monozygotic twins nearly 100% concordant COL1A1 associated in familial and sporadic cases Osteoporosis may be commoner in otosclerosis No severity difference, sporadic vs familial
- Measles-like structures in active lesions Immunohistochemical antigenicity demonstrated Measles RNA found in footplate specimens Raised anti-measles antibody in perilymph Incidence declined after measles vaccination
- Otosclerosis 1.4-2x more prevalent in women Pregnancy and lactation long said to accelerate it Reliable evidence for that claim is lacking Hormones may influence expression of disease Not a basis for advising against pregnancy
History of otosclerosis surgery
- Valsalva, Bologna: postmortem dissections in 1704 Found stapes fixation in a deaf individual Toynbee 1841 established deafness-fixation link Fixation in 39 of 1659 temporal bones Politzer 1893: primary labyrinthine capsule disease
- Three eras of surgery for otosclerosis
- Kessel of Graz: 'father of stapes surgery' Believed raised inner ear fluid pressure caused loss Removed the columella from two pigeons 1878: transtympanic mobilisation or extraction Reported some hearing gain, no serious complications
- Miot 1890: over 200 mobilisations under antisepsis 59% of his patients heard better Blake and Jack, Boston: mobilisation and removal Gains lasted days to weeks; labyrinthitis risk 1899 congress: surgery 'useless, mutilating, dangerous'
- Kessel 1876: hearing gain after lateral canal fracture Passow 1897: drilled fenestra in the promontory Floderus 1899: open vestibular labyrinth, skin graft Jenkins 1913: proposed fenestration for otosclerosis Principle: detour around the fixed oval window
- Holmgren 1920s: fenestrated canals but closed them Sourdille 1924: saw the flaw, exteriorised the fenestra Three-stage tympano-labyrintho-pexie 1937: lasting gain in 64% of 109 patients Lempert 1938: single-stage endaural fenestration
- Rosen performed exploratory tympanotomy first Purpose: confirm fixation before fenestration In the sixth patient he mobilised the stapes That patient's hearing markedly improved Many mobilised stapes later refixed
- Shea learned mobilisation from Rosen, 1953 Read Jack's 1902 double stapedectomy report Key idea: seal oval window with tissue, bridge gap Cortical bone failed; Teflon prosthesis succeeded Presented to the Triological Society, May 1956
- Complete footplate removal now reserved for select cases Replaced by limited removal, then precise fenestration Small fenestra developed early 1960s Shea in the USA; Marquet and Mignon in Europe Now the procedure of choice for most surgery
- Fenestra first made with handheld or electric microdrill Perkins 1980: 11 patients, laser stapedotomy Used microscope-mounted focused argon beam Schuknecht fat-wire prosthesis sealed and reconstructed Later designs vary in material, attachment, diameter
Diagnosis
- Progressive hearing loss, third or fourth decade >90% present before age 50 Bilateral in 75%, often asymmetric Juvenile onset is <1% of cases Family history of early hearing loss is common
- 10-30% report dizziness or vertigo Usually unsteadiness or brief, vague dizziness Severe episodic vertigo is not typical Episodes >20 min: consider Meniere's disease Saccule may abut the undersurface of the footplate
- Conductive loss with a normal-looking drum Schwartze's sign: promontory blush in active disease Exclude retraction pockets, tympanosclerosis, perforation Assess malleus movement on pneumatic otoscopy Note canal osteoma, exostoses or infection
- Verify the audiogram with a 512 Hz fork Weber should lateralise to the affected ear Many require a negative 512 Hz Rinne to operate Negative Rinne = bone conduction > air conduction Place fork posterior to pinna, below temporal line
- Air and bone thresholds, discrimination, reflexes Low-frequency conductive loss appears first Higher frequencies affected as disease progresses Maximum air-bone gap from fixation is 55-60 dB Gap >60 dB suggests ossicular discontinuity
- Raised bone-conduction threshold at 2000 Hz Common finding in otosclerosis An artefact, not true cochlear loss Related to resonance of canal and middle ear Often resolves after successful stapes surgery
- Otosclerosis versus superior canal dehiscence
- Adult with typical picture: imaging usually unnecessary CT reasonable when another pathology is suspected CT sensitivity for an otosclerotic focus 85-87% High-resolution CT in all children with conductive loss Looks for X-linked gusher syndrome and anomalies
Selecting the patient
- Stapedotomy is the commonest procedure Fenestra in footplate, piston through it to incus Stapedectomy removes part or all of the footplate Tissue graft over vestibule: fascia, perichondrium, vein Prosthesis then sits on the graft and the incus
- Stapes surgery is advanced otologic surgery Reliable results take about 50 procedures Case numbers have declined over time Trainees may need longer to reach proficiency Plan supervision and case volume accordingly
- Conductive component large enough to be noticed Air-bone gap 25 dB or more at 500-1000 Hz Negative Rinne on 512 Hz tuning fork Operate the worse-hearing ear first Second ear 6-12 months after a successful first side
- Coexisting SNHL is not a contraindication Counsel that a hearing aid may still be needed Far-advanced disease: stapedotomy may enable aid use Consider it before cochlear implantation in most cases Age alone does not exclude surgery
- Chronic eustachian tube dysfunction Tympanic membrane perforation or chronic otitis media Concomitant Meniere's disease Only-hearing ear, with narrow exceptions Occupations dependent on intact vestibular function
- Elective surgery: consent must be thorough Alternatives: conventional and bone conduction aids SNHL, including profound loss, in about 1% Perforation, facial paresis, dysgeusia, tinnitus Dizziness, failure to close gap, further procedures
- Chefs and sommeliers: chorda tympani injury risk Taste disturbance may be prolonged Pilots, divers, sky divers: barotrauma risk Barotrauma may cause SNHL or vertigo Diving safe after surgery if able to autoinsufflate
- Status of the lateral ossicular chain Presence and location of otosclerotic foci Round window patency Facial nerve course and any dehiscence Chorda tympani status; prosthesis type and size
- Local only, local with sedation (MAC), or general Local allows hearing and vestibular testing on table General preferred by many teaching institutions Avoids head movement and time pressure Juvenile cases: general anaesthesia is required
- Vital et al. 2008 compared 160 general, 108 local Profound loss 1.8% general versus 0% local Later systematic review covered 417 procedures No difference in postoperative air-bone gap No difference in SNHL or postoperative vertigo
- Stapes surgery is classed as clean otologic surgery Cochrane review found no evidence for prophylaxis Most centres still give antibiotics Rationale: infection risks deafness and labyrinthitis Steroid evidence is lacking; one study showed harm
Surgical technique
- Supine, head turned to the contralateral shoulder Head tilted downward 10-15 degrees Aim: drum brought near the horizontal plane Bed with a separate head rest helps Surgeon seated, legs on floor, back supported
- Theatre set-up for stapes surgery
- Transcanal approach is standard Endaural approach if more exposure is needed Operating microscope is traditional Endoscopic stapedotomy increasingly used Approach little changed since Shea's revival
- Irrigate canal, inspect drum, clear cerumen first Stabilise speculum by hand or holder Inject 5 mm lateral to bony cartilaginous junction Skin there is less tightly bound to bone Xylocaine with 1:40,000 adrenaline aids haemostasis
- 27-gauge 1.5-inch needle, 3 cc Luer lock syringe Start posteriorly, inject into previous wheal Save the anterior injection for last Forceful anterior injection tracks to facial nerve Dilate canal with graded specula to push fluid medially
- Probably the most critical injection Bend the 27-gauge needle 30 degrees Inject between 9 and 12 o'clock in a right ear About 12 mm lateral to the annulus Manubrial artery should blanch as you inject
- Sickle knife: vertical cuts at 6 and 12 o'clock Begin just lateral to the annular ligament Extend the vertical incisions 8-10 mm Join with a horizontal cut 8 mm lateral to annulus Cut fully through the vascular strip
- Tympanomeatal flap for access to the footplate
- Round knife elevates flap to the annular ligament Do not apply suction directly to the flap Identify the annular ligament positively Rosen needle enters at about 8 o'clock, right ear Stay just inferior to the chorda tympani
- Must see pyramidal process and tympanic facial nerve Remove bone with microdrill or House curette Preserve the chorda tympani Avoid downward pressure while curetting Downward force risks incus subluxation
- Check round window patency and record it Survey the oval window niche for otosclerosis Palpate malleus and incus for independent mobility Gently move the stapes suprastructure Proceed only if stapes fixed, malleus and incus mobile
- Traditional sequence of stapedotomy
- Sectioning the incudostapedial joint
- Division of the stapedial tendon
- Laser division of the posterior crus
- Attempted laser division of the anterior crus
- Anterior crus section often impossible or unnecessary Fracture suprastructure downward to the promontory Never fracture toward the facial nerve Remove the arch from the middle ear Assess footplate mobility before completing fracture
- Fenestra just large enough for the piston to move Microdrill or laser give similar success Drill: diamond burr slightly larger than piston Footplate can be very thin; minimal downward pressure Slightly large is safer than slightly small
- Cuts and coagulates with precision Applies no pressure and causes no gross movement Reduces risk of a floating footplate Can fenestrate an already mobile footplate Less perilymph movement, less inner ear irritation
- Laser types used for stapedotomy
- Seawater model compared laser wavelengths Argon and KTP travelled 229 feet to half absorption Er-YAG: 0.0007 mm to half absorption CO2 laser: 0.007 mm to half absorption Higher absorption means less energy in the vestibule
- Overlapping laser shots form a rosette pattern Rosette sized to the selected piston Allow 2-3 seconds between pulses The pause lets perilymph cool Laser first achieves haemostasis on footplate vessels
- Laser rosette on the stapes footplate
- Smoothing and sizing the fenestra
- Useful when suprastructure angles toward promontory Divide incudostapedial joint, leave lenticular on capitulum Laser divides tendon and posterior crus Complete fenestra, place and crimp prosthesis Then down-fracture the remaining suprastructure
- Mode of attachment to the incus Diameter and length of the piston or rod Material of construction Weight, which has little influence on hearing Some loops need crimping, others do not
- Robinson bucket cradles the lenticular process Nitinol coils around incus when heated by laser Nitinol results equivalent to other prostheses Nickel biocompatibility is a stated concern Self-retaining titanium clip prostheses available
- Ribbon gives wider, more stable contact with incus Wider contact than the older steel wire Platinum and titanium lack steel's coiling memory Easier to crimp manually Malleable shaft can be angled after placement
- Larger diameter should theoretically close gap better Effect expected at low and middle frequencies Some studies: 0.4 mm and 0.6 mm results similar Comparisons confounded by fenestra size, small samples Ceiling effect: most prostheses close the gap well
- Magnetic field can heat and move ferromagnetic metal Concern grows as field strengths increase Prostheses implanted since 1989 generally safe Considered safe up to 3 tesla Record prosthesis type for future imaging queries
- Piston should protrude into vestibule up to 0.25 mm Measured from undersurface of incus: add 0.25 mm Measured from top of long process: subtract 0.25 mm That corrects for thickness of the long process Add 0.25 mm more if shaft bending is anticipated
- Measuring the incus to footplate distance
- Confirm the loop is opened sufficiently first Grasp loop with smooth alligator forceps Hold at an angle allowing one-movement placement If piston misses, park it in the oval window niche Manipulate it into the fenestra as a separate step
- Crimp at the narrowest part of the long process Then slide prosthesis proximally for a better angle Both crimper claws must be visible to the surgeon Take a deep purchase on the incus Nitinol prostheses are crimped with laser heat
- Correctly crimped stapes prosthesis
- Improper or shallow crimping Elliptical rather than circular loop Friction between piston and oval window niche Friction against the walls of the fenestra Right-angled hook can improve the angle
- Some seal fenestra with vein or connective tissue first Others place blood or loose tissue around it after Return tympanomeatal flap to anatomical position Inspect for perforations and unfurl the edges Stabilise with Gelfoam, fill canal with bacitracin
- Floating footplate Comminuted fracture of the footplate Footplate removed during suprastructure dislocation Some revision procedures Instruments for small fenestra unavailable
- Stapedotomy compared with stapedectomy
Far-advanced disease, aftercare and results
- Air conduction thresholds >85 dB Bone conduction thresholds not measurable Limit is the audiometer, not the cochlea House and Sheehy advocated stapes surgery Still first line before cochlear implantation
- Shea: speech discrimination improved by 15% Lippy: further 32.7% gain over 2 years Stapedotomy far cheaper than cochlear implantation Prior stapedotomy does not harm later implant results Calmels: post-implant scores 70-95%, mean 80%
- Now outpatient or 23-hour observation surgery Discharge often a few hours after operation Transdermal scopolamine for vertigo prophylaxis Patch placed behind the contralateral ear Left in place for three days
- Keep the ear dry Avoid heavy lifting and Valsalva manoeuvres No nose blowing; sneeze with an open mouth Air travel permitted a couple of days later Review at three weeks
- Mineral oil in canal two nights before review Plug with cotton overnight, remove in the morning Softens dried blood for painless cleaning Three weeks: inspect ear, test with 512 Hz fork Three months: otologic exam and full audiogram
- Postoperative gap uses postoperative bone thresholds Follows AAO-HNS hearing committee guidelines Bone conduction often improves; Carhart notch resolves Experienced surgeons close gap to 10 dB in 90% Profound SNHL in no more than 1%
- Benchmark outcomes of stapes surgery
Intraoperative problems
- Occur when elevation is done in a limited segment Also when drum is elevated without the annulus Prevent by elevating in a broad plane Include the annulus with the flap Repair perforations before closing
- Occurs during curettage of the bony annulus Also during joint separation and crimping Subluxation: part of attachments disrupted Good result still likely with incus prosthesis Crimping onto a loose incus is harder
- Incus free to move in all four directions Best managed by removing the incus Perform a malleovestibulopexy Alternative: TORP onto perichondrium-covered fenestra Success rates are lower than for standard cases
- Verify nerve position as soon as niche is exposed Prolapse found in 40 of 1497 procedures (2.6%) Covered over half the niche in 1.9% Only four operations abandoned for this reason Abort if nerve abuts promontory below oval window
- Drill a small fenestra including inferior annular ligament Drill near midpoint of the inferior margin Promontory bone is thickest there Same technique as for a floating footplate Use a longer prosthesis, bent inferiorly
- Niche obliterated by thick footplate or margins Found in 14 of 293 primary procedures (4.7%) Laser inefficient at removing that much bone Saucerise the niche with a diamond burr Blue-line the remaining footplate, then remeasure
- Round window may be partly or wholly obliterated Complete obliteration causes significant conductive loss Attempts to clear it have caused SNHL Cannot judge partial versus complete at surgery Complete the operation and record the finding
- Normally regresses in the first trimester Traverses the obturator foramen of the stapes Seen surgically in 1 in 5000-10,000 ears Do not routinely coagulate the vessel Fenestrate posterior half if space is clearly sufficient
- Persistent stapedial artery at the footplate
- Malleus head fixed to epitympanic wall or roof Aetiology unrelated to otosclerosis 0.5% of temporal bone specimens; 1-2% surgically Reduced umbo and manubrium movement on otoscopy Usually unilateral, unlike otosclerosis
- Assess each ossicle separately by gentle palpation Option: remove incus and malleus head Reconstruct with a malleus attachment prosthesis Option: excise the fixed area after joint separation Address it at the same operation
- Fluid egress after fenestration is in fact CSF Oozer: steady trickle, patent cochlear aqueduct Gusher: forceful flow from cribrose area defect Defect lies at fundus of internal auditory canal CT may look normal despite a gusher
- Inspect round window membrane for bulging first Bulging: confirm the footplate is truly fixed If not, consider aborting the procedure Pack the fenestra with tissue or a cotton pledget Lumbar drain lowers CSF pressure
- Perilymph gusher at the oval window
- Depressed footplate causes immediate vertigo Once in the vestibule it cannot be safely extracted Laser fenestration reduces disarticulation risk Test footplate movement before completing fracture If mobile, divide crura before removing arch
- Laser can still fenestrate a floating footplate Otherwise burr a hole inferior to the annular ligament Elevate the footplate with a small hook Seal the opening with a tissue graft, place prosthesis Small fragments and bone dust rarely harm the ear
- Footplate subluxed into the vestibule
Postoperative complications
- Usually due to local anaesthetic, or nerve trauma Anaesthetic cause: overzealous anterior canal injection Anaesthetic palsy recovers within a few hours Weakness beyond 3 hours suggests true injury Nerve may be hit by curette, drill, or laser heat
- If nerve integrity is certain: eye care and steroids If uncertain and no recalled trauma: explore Transection is very rare Repair with or without a cable graft if found Delayed palsy: 0.5%, appears day 5 to 20
- Nerve exits posterior iter across the surgical field Injury causes hypogeusia and dysgeusia Fungiform papillae atrophy in the denervated area Symptoms commoner than after chronic otitis surgery Nerve is nearly always manipulated in stapes surgery
- Dried nerve recovers quickly and completely Severed nerve causes temporary symptoms Most improve over 3 to 6 months Stretched nerve causes the worst symptoms Consider sacrificing a significantly stretched nerve
- Early acute otitis media is worrying Risk of suppurative labyrinthitis and meningitis Pain and fever suggest those complications Remove canal packing, admit, broad-spectrum antibiotics After about 6 weeks, treat as for any patient
- Air entering the vestibule causes early vertigo Usually from suction at the oval window Pneumolabyrinth resolves in 24-48 hours Blood causes chemical irritation, resolves in days Vertigo beyond that suggests serious inner ear insult
- Uncommon after stapes surgery May be benign paroxysmal positional vertigo BPPV responds to repositioning physical therapy May instead indicate a perilymph fistula Fistula can occur early or late after surgery
- Exuberant granulation tissue reacting to surgery Triggers: glove powder, Gelfoam, prosthesis, perilymph Appears on the 5th to 15th postoperative day Hearing gain, then loss with dizziness and tinnitus Nystagmus beats toward the non-operated ear
- Clinical suspicion alone justifies re-exploration Aim: limit permanent inner ear dysfunction Remove granulation tissue and the prosthesis Seal the fenestra with a tissue graft Steroids may help; vestibular symptoms settle over weeks
- Transient bone dip <5 dB is common and benign Reflects mild serous labyrinthitis Early high-frequency loss suggests surgical trauma Delayed loss raises suspicion of perilymph fistula Fluctuating low-frequency loss suggests hydrops
- Causes of conductive loss after stapes surgery
- Incus erosion or necrosis at prosthesis site: 64% Malpositioned prosthesis: 41% Round window obliteration: 23% Bony regrowth at oval window: 14% Fibrous regrowth also reported
- Fluctuating loss, briefly improved by Valsalva Also improved by changing head position Progresses to complete discontinuity, large gap Cause: resorptive osteitis from differential movement Crimping does not strangle the incus blood supply
Cochlear otosclerosis
- SNHL in 20-30% of patients with otosclerosis Usually progressive over time Suspected mechanism: effect on the spiral ligament High-resolution CT may show pericochlear lucency Lucency reflects otic capsule demineralisation
- Historically used for cochlear otosclerosis Studies suggested modest slowing of SNHL Side effects were minimal Evidence limited and inconsistent Use has largely fallen out of favour
- Risedronate and zoledronate available Much more powerful anti-resorptive action Pilot study: no significant SNHL progression Mean follow-up about 13 months Systemic risks exceed those of fluoride
Summary
- Common cause of hearing loss; otic capsule dysplasia Autosomal dominant, penetrance 20-40% Ten loci identified; COL1A1 associated Measles-like structures found in active lesions Incidence fell after measles vaccination
- Options are amplification or stapes surgery Small fenestra stapedotomy is the usual procedure Performed with microdrill and/or laser Air-bone gap under 10 dB in 90% of patients Revision surgery has lower success, higher risk
- Sensorineural hearing loss in about 1% Chorda tympani dysfunction and vestibular injury Coexisting SNHL does not preclude surgery Amplification may still be needed afterwards Far-advanced disease may require cochlear implant
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- Haynes-Glasscock-Shambaugh Surgery of the Ear, Seventh Edition
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