Otosclerosis

Alan L. Cowan, MDTomoko Makishima, MD, PhD

Department of OtolaryngologyUniversity of Texas Medical BranchGalveston, TX

October 18, 2006

IntroductionOtosclerosis Primary metabolic bone disease of the otic capsule and ossiclesResults in fixation of the ossicles and conductive hearing lossMay have sensorineural component if the cochlea is involvedGenetically mediatedAutosomal dominant with incomplete penetrance (40%) and variable expressivity

History of Otosclerosis and Stapes Surgery1704 Valsalva first described stapes fixation1857 Toynbee linked stapes fixation to hearing loss1890 Katz was first to find microscopic evidence of otosclerosis1893 Politzer described the clinical entity of otosclerosis1890 Bacon describes medical therapy for the condition, and supports the common view that surgery should not be considered for a moment.

History of Otosclerosis and Stapes SurgeryGunnar Holmgren (1923)Father of fenestration surgerySingle stage technique

SourdilleHolmgrens student3 stage procedure64% satisfactory results

History of Otosclerosis and Stapes SurgeryJulius LempertPopularized the single staged fenestration procedure

John HouseFurther refined the procedurePopularized blue lining the horizontal canal

History of Otosclerosis and Stapes Surgery

Fenestration procedure for otosclerosisFenestration in the horizontal canal with a tissue graft covering>2% profound SNHLRarely complete closure of the ABGMay exhibit vestibular disturbances

History of Otosclerosis and Stapes SurgerySamuel Rosen1953 first suggest mobilization of the stapesImmediate improved hearingRe-fixation

History of Otosclerosis and Stapes SurgeryJohn Shea1956 first to perform stapedectomyOval window vein graftNylon prosthesis from incus to oval window

Epidemiology

10% overall prevalence of histologic otosclerosis1% overall prevalence of clinically significant otosclerosis

Epidemiology Race Incidence of otosclerosisCaucasian10%Asian5%African American1%Native American0%

EpidemiologyGender Histologic otosclerosis 1:1 ratio Clinical otosclerosis 2:1 (W:M)Possible progression during pregnancy (10%-17%)Studies which have demonstrated changes during pregnancy are often retrospective or lack audiometric data.Studies comparing multigravid vs. nulligravid women with otosclerosis have failed to show audiometric differences. Bilaterality more common (89% vs. 65%)

EpidemiologyAge15-45 most common age range of presentationYoungest presentation 7 years Oldest presentation 50s0.6% of individuals

Pathophysiology

Osseous dyscrasiaResorption and formation of new boneLimited to the temporal bone and ossiclesInciting event unknownHereditary, endocrine, metabolic, infectious, vascular, autoimmune, hormonal

PathologyTwo phases of diseaseActive (otospongiosis phase)Osteocytes, histiocytes, osteoblastsActive resorption of boneDilation of vesselsSchwartzes signMature (sclerotic phase)Deposition of new bone (sclerotic and less dense than normal bone)

Pathology

Most common sites of involvementFissula ante fenestrumRound window niche (30%-50% of cases)Anterior wall of the IAC

Non-clinical foci of otosclerosis

Anterior footplate involvement

Annular ligament involvement

Bipolar involvement of the footplate

Round Window

Labyrinthine Otosclerosis1912 Siebenmann described labyrinthine otosclerosisSuggested otosclerosis may cause SNHL viaToxic metabolitesDecreased blood supplyDirect extensionDisruption of membranes

Hyalinization of the spiral ligament

Erosion into inner ear

Organ of Corti

Cochlear OtosclerosisAudiometric studiesSome studies have shown that in cases of unilateral otosclerosis ~ 60% may have decreased sensory thresholds even after stapes surgery

Histiologic studiesCases of documented otosclerosis and a large sensory loss have shown large foci of otosclerosis in the otic capsule.Many cases of large otic capsule foci without sensory loss or of sensory loss without foci have also been described.

Biochemical studiesSome authors have noted increased levels of perilymph protein during stapedotomy in patients with radiographic evidence of otic capsule foci and sensory hearing loss.

ConclusionMany experts believe that extensive involvement of the cochlea will produce sensorineural hearing deficits, although it is not known how this occurs or why it only occurs in a subset of patients with cochlear foci.

Diagnosis of Otosclerosis

HistoryMost common presentationWomen age 20 - 30Conductive or Mixed hearing lossSlowly progressive, Bilateral (80%)Asymmetric Tinnitus (75%)

HistoryAge of onset of hearing lossProgressionLateralityAssociated symptomsDizzinessOtalgiaOtorrheaTinnitus

HistoryFamily history2/3 have a significant family historyParticularly helpful in patients with severe or profound mixed hearing lossPrior otologic surgeryHistory of ear infectionsVestibular symptoms25%Most commonly dysequilibriumOccasionally attacks of vertigo with rotatory nystagmus

Physical ExamOtomicroscopyMost helpful in ruling out other disordersMiddle ear effusionsTympanosclerosisTympanic membrane perforationsCholesteatoma or retraction pocketsSuperior semicircular canal dehiscenceSchwartzes signRed hue in oval window niche area10% of casesPneumatic otoscopyDistinguish from malleus fixation

Physical ExamTuning forksHearing loss progresses form low frequencies to high frequencies256, 512, and 1024 Hz TF should be usedRinne256 Hz negative test indicates at least a 20 dB ABG512 Hz negative test indicates at least a 25 dB ABG

Differential DiagnosisOssicular discontinuityCongenital stapes fixationMalleus head fixationPagets diseaseOsteogenesis imperfectaSuperior semicircular canal dehiscence

AudiometryTympanometryImpedance testingAcoustic reflexesPure tones

TympanometryJerger (1970) classification of tympanogramsType AType AType AsType AdType BType C

Acoustic ReflexesResult from a change in the middle ear compliance in response to a sound stimulusChange in compliance Stapedius muscle contractionStiffening of the ossicular chainReduces the sound transmission to the vestibule

Acoustic ReflexesOtosclerosis has a predictable pattern of abnormal reflexes over timeReduced reflex amplitudeElevation of ipsilateral thresholdsElevation of contralateral thresholdsAbsence of reflexes

Pure Tone AudiometryMost useful audiometric test for otosclerosisCharacterizes the severity of diseaseFrequency specific

Carharts notchHallmark audiologic sign of otosclerosisDecrease in bone conduction thresholds5 dB at 500 Hz10 dB at 1000 Hz15 dB at 2000 Hz5 dB at 4000 Hz

Pure Tone AudiometryLow frequencies affected firstBelow 1000 Hz

Rising air lineStiffness tilt Secondary to stapes fixation

With disease progressionAir line flattens

Pure Tone AudiometryCarharts notchProposed theoryStapes fixation disrupts the normal ossicular resonance (2000 Hz)Normal compressional mode of bone conduction is disturbed because of relative perilymph immobilityMechanical artifactReverses with stapes mobilization

Pure Tone AudiometryCommittee on Hearing and BalanceSet standards for reporting results in cases of otosclerosis procedures.Operative hearing results should be reported using post-operative data, specifically, the post-operative air-bone gap.This prevents exaggeration of surgical results and overclosure. Adopted by the AAOHNS in 1994Important in reviewing literature regarding surgical outcomesStudies prior to this time often use pre-op bone lines and post-op air conduction measurements which may exaggerate results.This convention is not uniform in all parts of the world, so the methods is very important in determining the consistency of data.

ImagingComputed tomography (CT) of the temporal boneProponents of CT for evaluation of otosclerosisPre-opCharacterize the extent of otosclerosisSevere or profound mixed hearing lossEvaluate for enlarge cochlear aqueductPost-opRecurrent CHLRe-obliteration vs. prosthesis dislocationVertigo

Halo sign

Pagets disease

Osteogenesis Imperfecta

Management OptionsMedical AmplificationSurgeryCombinations

Patient SelectionFactorsResult of tuning fork tests and audiometrySkill of the surgeonFacilitiesMedical condition of the patientPatient wishes

SurgeryBest surgical candidatePreviously un-operated earGood healthUnacceptable ABG25 to 40 dBNegative Rinne testExcellent discriminationDesire for surgery

SurgeryOther factorsAge of the patientElderlyPoorer results in the high frequenciesCongenital stapes fixation (44% success rate)Juvenile otosclerosis (82% success rate)OccupationDiverPilotAirline steward/stewardess

SurgeryOther factorsVestibular symptomsMeniere's diseaseConcomitant otologic diseaseCholesteatomaTympanic membrane perforation

Surgical StepsSubtleties of technique and styleLocal vs. general anesthesiaStapedectomy vs. partial stapedectomy vs. stapedotomyLaser vs. drill vs. cold instrumentationOval window sealsProsthesis

Canal Injection2-3 cc of 1% lidocaine with 1:50,000 or 1:100,000 epinephrine

4 quadrants

Bony cartilaginous junction

Raise Tympanomeatal Flap6 and 12 oclock positions

6-8 mm lateral to the annulus

Take into account curettage of the scutum

Separation of chorda tympani nerve from malleusSeparate the chorda from the medial surface of the malleus to gain slack

Avoid stretching the nerve

Cut the nerve rather than stretch it

Curettage of ScutumCurettage a trough lateral to the scutum, thinning it

Then remove the scutum (incus to the round window)

Curettage of ScutumExposure Vertical:Facial nerve to round windowHorizontal:Pyramidal process to malleus

Preservation of bone over incus

Middle ear examinationMobility of ossiclesConfirm stapes fixationEvaluate for malleus or incus fixation

Abnormal anatomyDehiscent facial nerveOverhanging facial nerveDeep narrow oval window nicheOssicular abnormalities

Measurement for prosthesisMeasurementLateral aspect of the long process of the incus to the footplate

Total StapedectomyUsesExtensive fixation of the footplateFloating footplateDisadvantagesIncreased post-op vestibular symptomsMore technically difficultIncreased potential for prosthesis migration

Stapedotomy/Small FenestraOriginally for obliterated or solid footplatesEurope1970-80

First laser stapedotomy performed by Perkins in 1978Less trauma to the vestibuleLess incidence of prosthesis migrationLess fixation of prosthesis by scar tissue

Drill Fenestration0.7mm diamond burrMotion of the burr removes bone dustAvoids smoke productionAvoids surrounding heat production

Laser FenestrationLaserAvoids manipulation of the footplateArgon and Potassium titanyl phosphate (KTP/532)Wave length 500 nmVisible lightAbsorbed by hemoglobin Surgical and aiming beamCarbon dioxide (CO2)10,000 nmNot in visible light rangeSurgical beam onlyRequires separate laser for an aiming beam (red helium-neon)Ill defined fuzzy beam

Oval window sealTragal perichondriumVein (hand or wrist)Temporalis fasciaBloodFatGelfoam (now discouraged)

Reconstructing the annular ligament

Placement of the ProsthesisProsthesis is chosen and length pickedSome prefer bucket handle to incorporate the lenticular process of the incus

Stapedectomy vs. StapedotomyABG closure < 10dB (PTA)

Special Considerations and Complications in Stapes Surgery

Overhanging Facial NerveUsually dehiscentConsider aborting the procedureFacial nerve displacement (Perkins, 2001)Facial nerve is compressed superiorly with No. 24 suction (5 second periods)10-15 sec delay between compressionsPerkins describes laser stapedotomy while nerve is compressedWire piston usedAdd 0.5 to 0.75 mm to accommodate curve around the nerve

Floating FootplateFootplate dislodges from the surrounding OW nicheIncidental findingMore commonly iatrogenicPreventionLaserFootplate control holeManagementAbortH. House favors promontory fenestration and total stapedectomyPerkins favors laser fenestration

Diffuse Obliterative OtosclerosisOccurs when the footplate, annular ligament, and oval window niche are involved Closure of air-bone gap < 10 dB less common.Refixation commonly occurs

Perilymphatic GusherAssociated with patent cochlear aqueductMore common on the leftIncreased incidence with congenital stapes fixationIncreases risk of SNHLManagementRough up the footplateRapid placement of the OW seal then the prosthesisHOB elevated, stool softeners, bed rest, avoid Valsalva, +/- lumbar drain

Round Window Closure20%-50% of cases1% completely closed

No effect on hearing unless 100% closed

Opening has a high rate of SNHL

SNHL1%-3% incidence of profound permanent SNHLSurgeon experienceExtent of diseaseCochlearPrior stapes surgeryTemporarySerous labyrinthitisReparative granulomaPermanentSuppurative labyrinthitisExtensive drillingBasilar membrane breaksVascular compromiseSudden drop in perilymph pressure

Reparative GranulomaGranuloma formation around the prosthesis and incus2 -3 weeks postopInitial good hearing results followed by an increase in the high frequency bone line thresholdsAssociated tinnitus and vertigoExam reddish discoloration of the posterior TMTreatmentME explorationRemoval of granulomaPrognosis return of hearing with early excisionAssociated with use of Gelfoam

VertigoMost commonly short lived (2-3 days)More prolonged after stapedectomy compared to stapedotomyDue to serous labyrinthitisMedialization of the prosthesis into the vestibuleWith or without perilymphatic fistulaReparative granuloma

Recurrent Conductive Hearing LossSlippage or displacement of the prosthesisMost common cause of failureImmediateTechniqueTrauma DelayedSlippage from incus narrowing or erosionAdherence to edge of OW nicheStapes re-fixationProgression of disease with re-obliteration of OWMalleus or incus ankylosis

AmplificationExcellent alternative Non-surgical candidatesPatients who do not desire surgery

Patient satisfaction rate lower than that of successful surgeryCanal occlusion effectAmplification not used at night

MedicalSodium Fluoride1923 - Escot suggested using calcium fluoride1965 Shambaugh popularized its useMechanismFluoride ion replaces hydroxyl group in bone forming fluorapatiteResistant to resorptionIncreases calcification of new boneCauses maturation of active foci of otosclerosis

MedicalSodium FluorideReduces tinnitus, reverses Schwartzes sign, resolution of otospongiosis seen on CT OTC FloricalDose 20-120mgIndicationsNon-surgical candidatesPatients who do not want surgerySurgical candidates with + Schwartzes signTreat for 6 mo pre-op Postop if otospongiosis detected intra-op

MedicalSodium fluorideHearing results50% stabilize30% improveRe-evaluate q 2 yrs with CT and for Schwartzes sign to resolveIf fluoride are stopped expect re-activation within 2-3 years

MedicalBisphosphonatesClass of medications that inhibits bone resorption by inhibiting osteoclastic activityDosing not standardOften supplement with Vitamin D and CalciumStudies conducted on otosclerosis patients with neurotologic symptoms report the majority of patients with subjective improvement or resolution.Future application of this treatment unclear, especially with new reports of bisphosphonate related osteonecrosis.

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