Ossicular Chain Reconstruction

Educational Objectives

The goal of this program is to improve outcomes of ossicular chain reconstruction. After hearing and assimilating this program, the clinician will be better able to:

1. Select patients with middle ear pathologies who are most likely to have improved hearing outcomes from ossicular chain reconstruction.
2. Utilize diagnostic techniques to identify the etiology of hearing loss.
3. Identify factors that can affect outcomes of ossicular chain reconstruction.
4. Prescribe nonsurgical alternatives to ossicular chain reconstruction for patients unlikely to benefit from surgery.

Summary

Overview: maintenance of the malleus during ossicular chain reconstruction is critical; stapedectomy is the most common procedure for otosclerosis

Pathophysiology of the ossicular chain: fixation — may include fixation of the malleus or anterior malleal ligament; discontinuity — observed in cases of cholesteatomas; long process of the incus is the most commonly affected area; conductive hearing loss of the inner ear — examples include enlarged vestibular aqueduct or dehiscence of the superior canal; chronic suppurative otitis media — commonly classified by presence of cholesteatoma; involvement of the ossicular chain is observed in ≈80% of cases with cholesteatoma; 20% to 25% of cases have involvement of the ossicular chain without cholesteatoma; tympanosclerosis and otosclerosis — most common disorders involving the ossicular chain, followed by trauma and congenital pathologies

Physical examination for patients with suspected pathology of the ossicular chain: otoscopy — includes pneumatic otoscopy and is performed to evaluate mobility of the tympanic membrane; tuning fork examination — recommended for all patients; tympanometry — recommended to measure acoustic reflexes and impendence; acoustic reflex testing can help distinguish between otosclerosis, ossicular discontinuity or fixation, or a third window effect in patients with conductive hearing loss, normal examination, and type A tympanometry; pure-tone audiometry — maximum conductive loss is 55 to 60 dB HL with complete discontinuity of the ossicular chain and intact tympanic membrane; with perforated tympanic membrane, hearing may be improved by 10 to 15 dB HL; severity of conductive hearing loss is difficult to predict on physical examination

Diagnostic imaging: computed tomography (CT) — recommended with thin cuts of ≤0.5 mm, field of view limited to the temporal bone, and contrast enhancement; conventional CT can be used if the resolution is high; evaluation of chronic ear disease — bone erosion, labyrinthine fistula, ossicular erosion, or erosion of the scutum and attic enlargement are reliable signs of a cholesteatoma; chronic ear issue without signs of cholesteatoma — malleus fixation is common in children; anterior malleal ligaments should be evaluated for attachments and sources of ankylosis; evaluation for ossicular erosion and demineralization of the malleus head or body of the incus is recommended

Third window effect: important to rule out when evaluating labyrinthine fistulas, large vestibular aqueducts, dehiscence of the superior semicircular canal, or other congenital anomalies on CT

Considerations for surgery: Eustachian tube dysfunction is primarily a bilateral disorder, and patients are poor candidates for ossicular chain reconstruction because prosthetics can move over time; uninvolved ear should be examined; unless clear indication for surgery (eg, cholesteatoma) is present, clinician should consider whether hearing aid or bone conduction device can achieve adequate rehabilitation; smoking status should be considered, and presence of active infection is considered a relative contraindication; perforated tympanic membrane may need to be fixed before reconstruction of the ossicular chain; surgery is unlikely to improve condition in patients with prior failed surgeries; long- and short-term outcomes should be considered

Alternatives to ossicular chain reconstruction: include active middle ear implantation, conventional hearing aids, and bone conduction devices; transcutaneous bone conduction implantations (eg, BONEBRIDGE or Osia System) produce good sound quality but are expensive

Goals of surgery: include recapitulation and maximization of the functional gain of the middle ear as an impedance transformer to deliver a strong signal to the inner ear; patient selection for surgery should be based on preoperative audiometry and potential to regain serviceable hearing; cochlear reserve and function of the inner ear should be considered; other considerations include condition of contralateral ear, history of prior surgery and Eustachian tube dysfunction, and condition of the intact or perforated eardrum

Ideal prosthetic: device should be biocompatible to integrate with tissues surrounding the middle ear with minimal formation of scar tissue, be lightweight and easy to modify during surgery, provide good transmission of sound, be moderately rigid, and be compatible with magnetic resonance imaging (MRI); titanium is the most commonly used material

Surgical procedure: local anesthesia — recommended to enable evaluation of hearing in real time; propofol is administered at the beginning of the procedure and wears off after surgeon obtains access to the middle ear, at which point the patient wakes up; hemostasis — important to prevent bleeding in the ear canal; injection of vascular strip and anterior canal is recommended, and injection of meatus should be performed at junction of hair-bearing area; approach — transcanal approach is recommended for most cases; endaural approach may be considered but is not commonly performed in United States

Postauricular transfacial recess procedure: effective for second-look surgery after canal wall up mastoidectomy, and outcomes are reliable because tympanic membrane is not moved and reconstruction is performed onto stapes superstructure

Tympanomeatal flap: should be tailored to goals of surgery, eg, for congenital cholesteatomas that need to be removed anteriorly from the tensor tympani tendon, adequate exposure is important, but moving tympanic membrane off the umbo should be avoided; therefore, tympanomeatal flap is based inferiorly, and the eardrum is lifted off the manubrium of the malleus but not the umbo

Approach considerations for patients with prior ear surgery: canal incision is altered for canal wall down procedure; mastoid segment should be covered by bone (if not, flap should be lifted cautiously); evaluation of middle ear is recommended for disease factors, secondary signs of Eustachian tube dysfunction, stapedius tendon, and residual cholesteatoma

Dehiscence of facial nerve after surgery: occurs in ≈60% of ear surgeries; to prevent occurrence, documentation of each ossicle in the operating report is recommended, and angle between the malleus and the stapes capitulum is evaluated

Austin-Kartush classification of ossicular defects: type A — incus is absent, and stapes and malleus are present; type B — malleus is present, and stapes is absent; type C — stapes is present, but the malleus and incus are absent (uncommon); type D — incus, malleus, and stapes are absent; type E — malleus is fixated; type F — stapes is fixated

Excessive tension during procedure: cutting of tensor tympani tendon is recommended to reduce tension

Type A ossicular defect: partial ossicular replacement prosthesis (PORP) is commonly used; large prosthetic heads are generally more difficult to place but more stable than small heads; heads with a hook placed under the malleus helps to secure prosthesis; prosthetic should be centered over the staples, with the head angled slightly inferiorly with adequate tension

Deposition of cartilage under the tympanic membrane: presence of cartilage is essential because it acts as an interface between the prosthetic and tympanic membrane and reduces risk for extrusion; tragus or conchal cartilage are usually used; perichondrium is removed to improve shaping of the cartilage; prosthetic is tilted posteriorly and inferiorly, cartilage is placed over the edge, and prosthetic is rocked back into position as a composite; prosthetic and cartilage can be glued or sewed together; subluxation of the prosthetic into the vestibule can fracture the footplate and should be avoided

Minor erosion of the incus: if identified during surgery, entire tympanic membrane should be removed and ionomeric bone cement should be applied, or incus should be removed; prosthesis (eg, angular clip or helix) can be used to bridge the gap between the long incus to the stapes capitulum

Type B ossicular defect: TORP is required if the stapes superstructure is absent and bridges the footplate to the malleus or tympanic membrane; foot shoe can be wedged into the middle of the remnant crura of the stapes; no surgical options are available if the footplate is absent or fixated, although a hearing aid or bone conduction device can be attempted; length and tension of the prosthetic should be assessed, and the measurement rods provided by the manufacturer can be used to measure from the stapes capitulum to the plane of the neck of the malleus (2-2.5 mm); excessive tightening of the annular ligament of the footplate can deepen sound conduction; prosthetic angle should reestablish contact with the malleus, and an interface angle of ≈30° with the neck of the malleus is recommended, while an angle >45° causes excessive tension of the annular ligament, which causes the stapes to tilt

Surgical outcome: postoperative air-bone gap — considered excellent if <10 dB, good if 11 to 20 dB, and fair if 21 to 30 dB; closing the air-bone gap to <20 dB is considered an ideal surgical outcome; selecting patients who are good candidates for surgery is critical because good outcomes cannot be obtained with some pathologies; Eustachian tube dysfunction — reduces rate of surgical success, and long-term outcomes are poor; mobile stapes superstructure — has a strong influence on long-term success and selection of PORP vs TORP; may act as a surrogate marker of disease severity; presence of malleus — individuals lacking a malleus are poor candidates for surgery

Use of TORP vs PORP: securing the medial anchor point is more difficult with a TORP; PORP can be clipped onto the stapes capitulum; TORP is longer (6-6.5 mm vs 2-2.5 mm for the PORP), which increases likelihood of tilting

Complications of surgery: intraoperative — subluxation of the prosthetic may lead to fracture of the footplate, which can cause vertigo and sensorineural hearing loss; delayed — extrusion is common and often reflects the severity of Eustachian tube dysfunction and whether cartilage was properly used to secure the device; reported rates of extrusion are 5% to 40% and also affected by the material used, with a rate of 1% using a titanium device with cartilage and 30.3% using hydroxyapatite without cartilage; other complications include erosion of the incus and abnormal tension with the prosthetic, which can cause dislocation or dislodging of the device

Readings

Albera R et al. Ossicular chain lesions in cholesteatoma. Acta Otorhinolaryngol Ital. 2012;32:309-313; Assis de Avila M et al. Imaging evaluation of middle ear cholesteatoma: iconographic essay. Radiol Bras. 2013;46:247-251; Bergevin C, Olson ES. External and middle ear sound pressure distribution and acoustic coupling to the tympanic membrane. J Acoust Soc Am. 2014;135:1294-1312; Blevins NH. Transfacial recess ossicular reconstruction: technique and early results. Otol Neurotol. 2004;25:236-241; Gelfand YM, Chang CY. Ossicular chain reconstruction using titanium versus hydroxyapatite implants. Otolaryngol Head Neck Surg. 2011;144:954-958; Kotzias SA et al. Ossicular chain reconstruction in chronic otitis media: hearing results and analysis of prognostic factors. Braz J Otorhinolaryngol. 2020;86:49-55; Luers JC, Hüttenbrink KB. Surgical anatomy and pathology of the middle ear. J Anat. 2016;228:338-353; Mudhol RS et al. Ossiculoplasty: revisited. Indian J Otolaryngol Head Neck Surg. 2013;65:451-454; Schairer KS et al. Acoustic reflex measurement. Ear Hear. 2013;34:43S-47S; Wiatr M et al. Determinants of change in air-bone gap and bone conduction in patients operated on for chronic otitis media. Med Sci Monit. 2015;21:2345-2351.

Disclosures

Dr. Adunka worked as a consultant for Advanced Bionics Corporation, AGTC Inc, MED-EL Corporation, and Spiral Therapeutics; is a part owner of Advanced Cochlear Diagnostics; received research support from Advanced Bionics Corporation, Cochlear Corporation, and MED-EL Corporation; and received royalties from Advanced Bionics Corporation. Members of the planning committees reported nothing to disclose.

Acknowledgements

Dr. Adunka was recorded exclusively for Audio Digest using virtual teleconference software, in compliance with current social distancing guidelines during the COVID-19 pandemic, on October 19, 2020. Audio Digest thanks the speakers and sponsors for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0 CE contact hours.

Lecture ID:

OT540601

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.