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Differential diagnosis of Hearing loss

Differential diagnosis of Hearing loss. 1.Conductive Hearing loss 2.Sensorineural Hearing loss 3.Mixed Hearing loss. DIAGNOSIS AND Assessment of hearing loss. HISTORY Screening test-Behavioural tests Speech test Tuning fork test Pure tone Audiometry Speech audiometry

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Differential diagnosis of Hearing loss

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  1. Differential diagnosis of Hearing loss 1.Conductive Hearing loss 2.Sensorineural Hearing loss 3.Mixed Hearing loss

  2. DIAGNOSIS AND Assessment of hearing loss • HISTORY • Screening test-Behavioural tests • Speech test • Tuning fork test • Pure tone Audiometry • Speech audiometry • Impedence Audiometry • ABLB, SISI, TD • Electrocochleography • Auditory brain stem response • Otoacoustic emissions

  3. Causes of conductive loss • Congenital Meatal Atresia congenital cholesteatoma ossicular discontinuity Fixation of malleus Fixation of stapes

  4. Acquired Causes of conductive loss • Acquired causes EXTERNAL EAR meatal aresia wax foreign body furuncle tumour acquired atresia

  5. Acquired Causes of conductive loss • Middle ear Serous otitis media Otosclerosis Ossicular discontinuity Adhesive otitis media Tympanosclerosis Csom ASOM TUMOUR Trauma


  7. HEARING AIDS 1.Microphone 2.Amplifier 3.Receiver

  8. Hearing aids • Sounds-----microphone volume control battery amplifier receiver amplified sounds


  10. bte

  11. In the canal

  12. Completely in the canal

  13. Electroacoustic properties of the hearing aid • Acoustic gain • Frequency response • Maximum output • Distortion

  14. ASISTED LEARNING DEVICE • FM • Hard wire system, class room amplification • Telecommunication device for the deaf • Alerting device for the deaf

  15. Cochlear implants • Electronic devices designed to detect mechanical sounds and convert it into electrical signals that can be delivered to cochlear nerve and interpreted by the patients to provide useful hearing.

  16. History of Cochlear Implants • Volta • Djourno and Eyries • House, Doyle, Simmons • 1972 Single-channel implant • 1984 FDA approval • 1990’s • Beyond

  17. Anatomy

  18. Anatomy Scala tympani Scala vestibuli Cochlear duct Basilar membrane Vestibular membrane Tectoral membrane Hair cells (outer/inner) Cochlear nerve fibers

  19. Anatomy-micro

  20. Physiology of Hearing

  21. Anatomy

  22. Pathologic Anatomy

  23. Components of Cochlear Implant

  24. Implant Components • Microphone • amplification • External speech processor • Compression • Filtering • Shaping • Transmitter (outer coil) • Receiver • Electrode array • Neural pathways

  25. Types of Cochlear Implants • Single vs. Multiple channels • Audio example of how a cochlear implant sounds with varying number of channels • Monopolar vs. Bipolar • Speech processing strategies • Spectral peak (Nucleus) • Continuous interleaved sampling (Med-El, Nucleus, Clarion) • Advanced combined encoder (Nucleus) • Simultaneous analog strategy (Clarion)

  26. Anatomy of a Cochlear Implant

  27. Indication for Cochlear Implant • Adults • 18 years old and older (no limitation by age) • Bilateral severe-to-profound sensorineural hearing loss (70 dB hearing loss or greater with little or no benefit from hearing aids for 6 months) • Psychologically suitable • No anatomic contraindications • Medically not contraindicated

  28. Indications for Cochlear Implantation -- Children • 12 months or older • Bilateral severe-to-profound sensorineural hearing loss with PTA of 90 dB or greater in better ear • No appreciable benefit with hearing aids (parent survey when <5 yo or 30% or less on sentence recognition when >5 yo) • Must be able to tolerate wearing hearing aids and show some aided ability • Enrolled in aural/oral education program • No medical or anatomic contraindications • Motivated parents

  29. Contraindications • Incomplete hearing loss • Neurofibromatosis II, mental retardation, psychosis, organic brain dysfunction, unrealistic expectations • Active middle ear disease • CT findings of cochlear agenesis (Michel deformity) or small IAC (CN8 atresia) • Dysplasia not necessarily a contraindication, but informed consent is a must • H/O CWD mastoidectomy • Labyrinthitis ossificans—follow scans • Advanced otosclerosis

  30. General Workup • Audiologic exam with binaural amplification • CT scan/MRI of temporal bones • Trial of high-powered hearing aids • Psychological evaluation • Medical evaluation • Any necessary tests to discover etiology of hearing loss

  31. Surgical technique

  32. Surgical Technique

  33. Surgical Technique

  34. Postoperative Management • Complication rate only 5% • Wound infection/breakdown • Yu, et al showed good response to Abx, I&D • Facial nerve injury/stimulation, CSF leak, Meningitis • CDC recommendations • Vertigo (Steenerson reported 75%) • Device failure—re-implantation usually successful • Avoid MRI

  35. Postoperative Rehabilitation • Necessary part of implantation • Different focus depends on patient’s previous experience with sound • Goal is to enable children to be able to learn passively from the environment • Program addresses receptive as well as expressive language skills • Multidisciplinary, dedicated group necessary

  36. Results of Implantation • Wide range of outcomes • Improvement is long-term (Waltzman, et al. 5-15 yr f/u) • Implantation is cost effective—even in the elderly (Francis, et al) • Research indicates recipe for success includes: • Short length of time from deafness to implantation (Sharma showed <3.5 years regain normal latencies within 6 mos. After 7 years, little plasticity remains) • Experience with language before onset of deafness • Implantation before age six for prelingually deafened children (Govaerts, et al showed 90% of children implanted <2yo were integrated into mainstream vs. only 20-30% if implanted after age 4) • Aural/oral education • Highly motivated patients/parents

  37. A Look to the Future • Partial implants with hearing aid • Those with residual low-frequency hearing • Intraoperative mapping • Bilateral implantation • One vs. two speech processors • Implantation for asymmetric SNHL • “Softip” array • Minimally invasive implantation


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