Bchas zeeshan

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Deptt of ENT, NMCH,Patna

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Bchas zeeshan

  1. 1. Bone Conducting HearingAid SolutionsDr Zeeshan Ahmad Department of ENT,M.S.(ENT,PGY1) NMCH,Patna. 27-09-2012
  2. 2. Hearing impairment is a common occurence.Most patients have abnormality of cochlear function and can be treated by use of conventional hearing aid.However, a significant number have conductive cause.Many of these can also be treated by conventional hearing aid but a proportion do not tolerate mould or insert in ear canal, so alternative means must be considered.
  3. 3. What is Hearing aid? A hearing aid is a battery-powered, electronicdevice that makes listening easier for peoplewith a hearing loss. A hearing aid consists of amicrophone, an amplifier and a receiver. Themicrophone picks up sounds in your acousticenvironment and turns them into electronicsignals. The amplifier selectively amplifies theacoustic electronic signals. The receiver is avery small speaker that changes the electricsignals back to sounds and delivers the sound tothe ear.
  4. 4. Consideration in using Hearing aids
  5. 5. History1551- Bone conduction device consisting of metal shaft or spear.1670- Sir Samual Moreland, England invented a large speaking trumpet.1892- first patent for electric hearing aid in the U.S.1912- first volume control for a hearing aid.
  6. 6. History Contd….1931- first electric hearing aid eyeglass patent1937- first wearable vacuum tube HA in US1953- first all-transistor hearing aid1987- first commercially available implantable hearing aid system.1997- FDA approved BAHA®Recently- Oticon implants
  7. 7. Basic Hearing Aid Structure
  8. 8. MECHANISM of BONECONDUCTION HEARINGVibration of bone of skull is coupled to soft tissues of ear canal. More when ear canal is occluded.Some of sound energy transmitted directly to ossicular chain.Alternate compression and expansion of cochlear shell by vibratory forces on bone.
  9. 9. The BAHA ®BAHA® is the trade namefor bone anchored hearingaid system available FromCochlearTM.
  10. 10. BAHA system is comprised of threeparts: Titaniumfixture(3) Connecting abutment(4) Detachable sound processor(6)
  11. 11. How does it Work? The processor receives sound through the abutment and sends it to the functioning cochlea using the skull as a pathway to bypass the outer and middle ears
  12. 12. CandidatesChronic otitis media Acoustic neuromaCongenital aural Neurologic atresia degenerative diseaseMicrotia Meniere’s diseaseCholesteatoma Viral infectionMiddle ear Trauma dysfunction or disease
  13. 13. A photograph from NMCH OPD
  14. 14. PrerequisitesMixed or conductive hearing lossBone conduction pure-tone average in the indicated ear is greater than or equal to 45 dB HLMonosyllabic word discrimination score ≥ 60%For single sided DeafnessFor bilateral fittings – candidates must have symmetrical bone conduction pure-tone averages between earsAge > 5 years
  15. 15. To anticipate a "high success rate" with BAHAPatients should have a PTA less than 45 dB, although improvements in hearing should still be expected for a PTA of up to 60 dB.(Hakansson B, Tjellstrom A, Carlsson P:  Percutaneous vs. transcutaneous transducers for hearing by direct bone conduction.   Otolaryngol Head Neck Surg  1990; 102:339-344.)
  16. 16. Operative TechniqueA. Posterior-based skin flap is elevatedB. Flap is thinned until all hair follicles are removed fromthe flap centerC. Soft tissues beneath and adjacent to the flap are excisedto create a smooth transition from surrounding tissue tothe thin central skin flap
  17. 17. Operative TechniqueD. 3- to 4-mm hole is drilled in mastoid or retromastoidcortex.E and F, A countersink creates a recessed surface forimplant placement.
  18. 18. Operative TechniqueG. The hole is tappedH. Titanium screw is implantedI. Titanium screw is tightened in place
  19. 19. Operative TechniqueH/I. The titanium screw is tightened into placeK. The skin flap is replaced
  20. 20. Operative Technique L/M. Metallic abutment for later attachment of thevibrating external hearing aid is attached to the screwN/O. A healing cap is placed to apply pressure to the skinflap
  21. 21. Perioperative Complications with theBone-Anchored Hearing AidLoss of Skin GraftGrowth of skin graft over the abutmentImplant extrusionInfection
  22. 22. The most important factor inobtaining a trouble-free bone-anchored hearing aid (BAHA) site is:A. Having thin, immobile, hairless skin around the abutmentB. Using a 4-mm fixture flangeC. Using a longer abutment – The longestD. Performing surgery in two stages
  23. 23. To Prevent Loss of Skin GraftHave thin, immobile, hairless skin around the abutment - This allows for placement of the fixture in a tissue bed that has minimal local tissue reaction to the implant and thereby minimizes chance of skin graft loss, infection or extrusionEnsure that the skin graft is firmly attached to the underlying periosteumEnsure that the fixture and skin penetrating abutment are firmly secured
  24. 24. To prevent growth of skin graftover the abutmentUse longest implant possibleObtain adequate removal of surrounding soft tissueApproximate the surrounding skin edges to the periosteum
  25. 25. To prevent implant extrusionAllow patients with poor wound healing and thin bones to have six months of osseointegrationFix any coagulopathies that the patient may have pre-operativelyMaintain proper hemostasis to prevent hematoma formationUse a 4-mm fixture if there is bone still present at the bottom after using a 4-mm drill guidePatients with thin, brittle bone should have a two stage surgery
  26. 26. To prevent infection
  27. 27. Other complicationsPenetration of sigmoid sinus – Insert bone wax or muscle plugBrain abscess
  28. 28. OTICON PONTO HEARING AID
  29. 29. SOPHONO ALPHA 1 SYSTEM
  30. 30. THANKYOU for patient listening

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