TRANS 31 and 32 Flashcards
Indications for Hearing Aid
Any individual who has hearing problem that cannot be
helped by medical or surgical means is a candidate of
hearing aid
KINDS OF HEARING AIDS
- Conventional hearing aids
- Bone Anchored hearing aids (BAHA)
- Implantable hearing aids (vibrant sound bridge)
Components of conventional hearing aids
• Microphone: Receives sound and converts it into electrical
impulses (picks up sound)
• Amplifier: Intensifies electrical impulses (makes sound
louder)
• Receiver/Speaker: Translates those electrical impulses into
louder sounds
• Battery: Serves as power source for device
• Earmolds (earpiece): Directs the flow of sound into the ear
and enhance sound quality
2 types of conventional hearing aids
Analog and Digital
What type of conventional hearing aid?
Converts sound waves into electrical signals
o Custom built for each user
o Less expensive
Analog
What type of conventional hearing aid? o Converts sound waves into numerical codes
o Similar to binary code
o More flexibility in adjustment
Digital
• The amplified sound is transmitted via the ear canal to the
tympanic membrane
• Most of the aids are air conduction type
• They can be of 5 types
Air conduction hearing aid
• Instead of a receiver, it has a bone vibrator which snugly
fits on the mastoid & directly stimulates the cochlea
• Useful in persons with actively draining ears, otitis externa
or atresia of the ear canal when ear-inserts cannot be worn
Bone conduction hearing aid
• MOST COMMON • Microphones and amplifier along with the battery are in one case worn at the chest level while receiver is situated at the ear level • Allows high degree of amplification • Useful in severely deaf persons or children with congenital deafness
What type of hearing aid
Body worn type
What hearing aid?
• A modification of “behind-theear” type & the units housed in the auricular part of the spectacle frame • Useful to persons who need both eye glasses for vision and hearing aid
Spectacle types
What hearing aid
• Microphone, amplifier receiver and battery are all in one unit which is worn behind the ear • Coupled to the ear canal with a tubing and an earmold • Useful for slight to moderate cases of hearing loss?
Behind The Ear types
• Entire hearing aid is housed in an earmold which can be worn in the ear • Useful in mild to moderate hearing loss • Very popular because of their cosmetic appeal
what hearing aid?
In the ear
• The hearing aid is so small that the entire aid can be work in the ear canal without projecting into the concha
• For using this aid, it is required that the ear canal should be large and wide
• Patient should have dexterity to manipulate the minute controls in the aid
• Useful in mild to moderate
hearing loss
what hearing aid?
canal types. ( in the canal and completely in the canal)
• Based on the principle of bone conduction
Nakakabit sa bone, the sound is gathered outside but it is transferred directly to the mastoid bone, natransfer yung sound through vibration directly to the cochlea
what hearing aid?
Bone Anchored Hearing Aids
- Works on a DIRECT DRIVE PRINCIPLE
- Rather than delivering acoustic energy into the external auditory canal (as with traditional hearing aid systems), direct drive middle ear implant systems use mechanical vibrations delivered directly to the ossicular chain, while leaving the ear canal open.
Implantable hearing aids
• Electronic device that can provide useful hearing and improved communication abilities for persons who have sever to profound hearing loss and who cannot benefit from hearing loss
• Work by producing meaningful electrical stimulation of the auditory nerve
Yung mga infants na bagsak ABR, ESSR, especially if you have cochlear problems
Cochlear implants
- Designed to stimulate cochlear nuclear complex in the brainstem directly by placing the implant in the lateral recess of the fourth ventricle
- Such implant is needed when CN VIII has been severed in surgery of vestibular schwannoma
- ABI help in communication, awareness and recognition of environmental sounds
- They are not efficient as multichannel cochlear implants
Auditory brainstem implant
transduction of sound to neural impulses and its
interpretation by the CNS
Hearing
How would you define disabling hearing loss?
hearing loss >40 dB in the better
hearing ear in adults (15 years or older) and >30 dB in the
better hearing ear in children (0-14 year)
when is deafness used?
Deafness is used, when there is little or no hearing at all.
WHO in 1980 recommended to use term “Deaf” only when
hearing impairment not benefited from any amplification of
sound
4 types of hearing loss?
• Conductive (CHL)- sound is not conducted efficiently through
the outer ear canal to the eardrum and the tiny bones
(ossicles) of the middle ear
The outer ear and the middle ear, yun ang may problema.
The sound can’t be transferred from the outside to the
cochlea
• Sensorineural (SNHL)- damage to the inner ear (cochlea), or
to the nerve pathways from the inner ear to the brain
• Mixed- combination of CHL and SNHL
• Central- problem lies in the central nervous system
• Any disease process which interferes with the conduction of sound to reach cochlea causes conductive hearing loss
The bproblem is from outer ear to the inner ear
• Lesion may be in:
o External ear/ EAC
o Tympanic membrane
o Ossicles
what hearing loss?
CHL
• Results from lesions of: o Cochlea o VIII nerve o Central auditory pathway lesion o It can be congenital or acquired
what hearing loss?
SNHL
o (+) Rinne test, i.e. AC>BC o Weber lateralized to better ear o Reduced absolute bone conduction test o More often involving high frequencies o No gap between air and bone conduction curve on audiometry o Loss may exceed 60 dB
what hearing loss?
SNHL
defined as 30 dB or more of SNHL over at least three contiguous frequencies occurring within a period of 3 days or less
Sudden hearing loss
Reduction in auditory acuity associated with noise exposure, may be hours to days
Or it can be one-time big time
Noise induced hearing loss
high levels of continuous or intermittent noise for seconds to hours
Ito yung tinatawag kong one-time big time… nasabugan ka ng granado or may pumutok na plapla sa tenga mo, it is not only there be conductive but also sensorineural problem
Acute Noise Induced hearing loss
is yung threshold sa audiogram. Sometimes its temporary but kung biglang-bigla yan it will become permanent na
• Ex; loud power tools, rock concerts, engine noise
Concert- paglabas mo maingay, paglabas mo parang medyo bingi, may tumutunog sa tenga, after one hour wala na that is what you called Temporary Threshold Shift. Kung paulit-ulit mong ginagawa yun, eventually magiging permanent na yun
(TTS/ Temporary Threshold Shift)
irreversible cochlear hearing loss (PTS/ Permanent Threshold Shift)
• Typical features of sensorineural hearing loss
• Tinnitus can be constant
• Safe if levels below 85 dB for 8hrs/day
Chronic noise induced hearing loss
Acute acoustic trauma vs blast injury?
o Acute acoustic trauma- sudden intense sound event of short duration exceeding 140 dB and pressure rise is very short (<1.5 ms) e.g. Gunshot
o Blast injury- pressure wave from an explosive blast exceeds 140 dB but duration of pressure rise is longer (>2ms)
▪ Longer frequency spectrum
▪ Rupture tympanic membrane
• Infection or inflammatory process affecting the labyrinth or its surrounding
Labyrinthitis
3 routes of labyrintthitis?
Tymapnogenic, meningeal and hematogenous
o Age related (over 50 y/o) symmetrical SNHL
o Ageing process
o Endogenous genetic predisposition
o Cumulative exposure to exogenous factors
o Symptoms:
▪ Speech recognition more affected than pure tone
o Diagnosis:
▪ Pure tone audiometry- Symmetrical SNHL (High tone loss)
presbycussis
It has two categories of medications that have the greatest potential for permanent changes in hearing and or balance are:
o Aminoglycosides
o Anti-neoplastic agents
More vestibulotoxic than cochleotoxic.
Gentamicin
more vestibulotoxic? morecochleotoxic?>
Gentamycin and streptomycin
Amikacin and neomycin
- Highest ototoxic potential and is the most ototoxic drug in clinical use
- Symptoms of ototoxicity begin with tinnitus and high frequency hearing loss
- Incidence of hearing loss has been reported at 11-91% with overall incidence of 69%
- In patients with head and neck cancer treated with Cisplatin, about 50% develop hearing loss
cisplatin
