Balance and Pure Tone Testing Flashcards
Vestibular portion of the inner ear:
- Semicircular canals
- Utricle and saccule
Semicircular canals are needed for:
angular movement and body in space information
Utricle and Saccule needed for:
linear movement and speed/direction
Stereocilia Parts
- Kincocilium
- Sterocilia
- Otolithic membrane
- Cupula
Kinocilium
- longest hair cell at the top of the cell
- tubular with decreasing stiffness form bottom to top
Sterocilia
-bundle of hair cells (similar to the hearing mechanism)
Otolithic Membrane
- gelatinous membrane in saccule and utricle
- contains otoconia (calcium carbonate crystals)
Cupula
-Gelatinous membrane in semicircular canals
Stereocilia Functions/uses
- resting potential (firing rate)
- movement of stereocilia causes change in potential
Stereocilia movement toward the kinocilium will:
Excite nerve
increase firing rate
Stereocilia movement away from the kinocilium will:
inhibit the nerve
decrease the firing rate
True or False
The vestibular system is tied to the visual system
True
Vestibulo-ocular reflex:
-eyes move opposite of head turn or stay steady
Saccade System
Quick return of the eyes to direction of head turn
Smooth Pursuit
“tracking” an image with smooth eye movements
Optokinetic system
combination of saccade and smooth pursuit
Nystagmus
- results from an abnormal neural connection between the vestibular and visual systems
- can be symptomatic or benign
- constant shifting of eyes
- slow movement in one direction, fast return in opposite direction
Electro-oculography
-electrodes placed around the eyes, measures eye movements while turning the head
Proprioceptive/Somatosensory Kinesthesia
-info about posture, movement and body in space
-Supports balance via pressure sensors,
tactile cues,
muscular input (length, pressure, tension and noxious stimuli),
joint pressure, position and movement
Balance Testing
- symptoms can be acute or chronic (ENT visit first, mud history)
- Rule out neurological or cardiac involvement (MRI or cranial nerve testing)
- Determine peripheral vs central etiology (spontaneous or evoked nystagmus, Fernzel glasses prevent fixation)
ENG/VNG
-electronystagmography or videonystagmography
1. electro-oculography tests the semicircular canals
2. Oculo-motor evaluation. Saccade, smooth pursuit, optokinetic and gaze fixation.
3. Dix Hallpike Maneuver
BPPV: benign paroxysmal positional vertigo
4. positional testing (9 positions and recordings)
5. Calorics (Warm/cool air or water interacts with the endolymph)
What is the only balance test that evaluates the posterior canal?
Dix Hallpike Maneuver (BPPV)
What is the only balance test that shows ear specific data on the horizontal canal and/or vestibular nerve?
-Calorics
Explain Calorics
- warm/cold air or water is introduced into the ear canal and reacts with the endolymph.
- Heat makes the endolymph less dense and it moves cupula toward utricle
- Cool makes the endolymph thick and dense which moves cupula away from the utricle
- this creates a very dizzying effect
Rotational Chair Testing
- dark room
- head attached/secured to chair
- Record eye movements as chair moves
Postural Control Testing
- Assesses vestibular, ocular and proprioceptive systems
- Floor sways/moves
- patient is harnessed for safety
Describe self rating scales and why they are useful
- pre and post testing
- patient perceives impact on their lives (functional psychological and physical)
- used to quantify improvement after rehab services
7 parts of Rehabilitation:
- Home exercises
- low sodium diet
- Medication
- Desensitization/habituation of vestibular responses
- physical therapy to increase proprio-receptive system
- Surgery
- Vestibular Rehabilitation (increase central compensation)
Pure Tone testing
- Quantify auditory access to each frequency needed for speech perception
- ear specific info
- Helps us predict communication struggles (speech banana/articulation index)
- Used to prescribe hearing aids, CI, etc.
Audiometer
- screening or diagnostic
- Two channel allows for testing and masking
- stimulus=puretone, live voice, recorded speech, noise, etc
- Transducer=supra-aural headsets, inserts, speaker, bone oscillator
- Routing=right, left, both
Types of transducers:
- Earphones (supra-aural)
- Earphones (Circum-aural)
- Insert earphones
- Bone oscillator/Conductor
- Speaker
Earphones (Supra-aural)
Pros
-very easy to clean, -patient familiarity
Cons
-collapsed canal
-more crossover sound
(distance from earphone to eardrum can cause sound wave to cancel out)
Earphones (Circum-aural)
Pros -less constricting -more comfortable Cons -sound leaks around the headset -less accurate results
Insert Earphones
Pros -reduces "turtle effect" in children -no standing wave -less masking needed -no collapsed canals Cons -disposable and more costly -can't use if there is a drainage
Bone Oscillator/Conductor
-Placement is important!
on mastoid bone but not touching pinna
-Pitfalls: may fall off easily
Speaker
Pros
-can be used with difficult patients
Cons
-no ear specific info
Attenuators of an Audiometer:
-Decibels: (-10 dBHL to 120 dBHL)
some only go to 110 dBHL
-Frequency (125-8000Hz)
some capable to go to 12,000
Calibration of an Audiometer:
- annual assessment
- computer based equipment is more stable than portable equipment
Correction Factors for an Audiometer:
- dBHL to add/subtract per frequency
- sticker placed on audiometer
- Can be different for each transducer
Testing Environment:
- quiet room for screening
- diagnostic in sound treated room (NOT SOUND PROOF)
- double walled booth with sound absorbing material with holes to expose this material
- floor is carpeted with padding and raised above the ground to reduce vibrational noise
- double doors with thick molding
- windows are insulated
- fire alarms only if sprinkler goes off it ruins material
- special lights
- quiet ventilation
Pre Evaluation
- File review
- case history
- self rating scales
- conversation
- Otoscopy
Testing…
- seating
- clear, concise instructions
- mode of response
- transducer selection
Threshold Search
- tone presentation
- Ascending technique
- descending technique
- combo approach
- threshold criteria
- frequency progression
Tone presentation of a threshold search
- give one presentation at dBSL to alert
- 1-2 second duration
- pure tone, warble or pulsed tones
- vary the wait time
Ascending technique
-start at 0 dBHL and work up in 10 dB steps
Descending technique
-start at alerting tone and work down in 10 dB steps
Combination approach
- give alerting tone and work down in 10 dB steps
- missed response, go up in 5 dB steps
- very common now
Threshold criteria (ASHA 2005)
- respond 50% of the time
- 2/3 presentations elicit response
Frequency Progression
- start at 1k, then 2-8k
- however 3 and 6 are rarely tested
- return to 1k for a reliability check then 250 and 500 Hz
- More than a 20 dB difference between frequencies, add interoctave testing (750, 1500Hz)
When there is no response to 1K Hz tone…
- increase by 20 dBHL and try again
- switch to 500 Hz at same dBHL and try again
- reinstruct
False positives
- eager to please, ringing, nervous, afraid to fail
- reinstruct, change wait time, change Hz
- use another signal (Pulse, NBN or warble)
False negatives
- need to be sure, afraid, confused, malingering, ADD/ADHD
- reinstruct, change signal , give reassurance of correct answers
Pediatric testing
- use second tester to assit
- try to get low frequency and high frequency info for each ear (500Hz 4000Hz)
- Need to move quickly
- keep child’s attention
- Use reinforcers
PTA
- pure tone average
- 500 Hz + 1k +2k / 3 =PTA
- may not reflect loss
- may underestimate impact of loss
Tactile Responses
- low frequencies are affected (felt)
- Transducer contact
- Profound hearing loss
Bone conduction testing threshold search
- combination technique
- frequency progression
- unmasked thresholds could be a “better ear” response
Bone conduction testing placement options
- mastoid
- forehead
Masking
- 2 channel audiometer required
- used when there is an asymmetrical loss
- stimulus: speech or noise
Speech Stimulus
- babble
- nonsense
- speech weighted noise
Noise Stimulus
- narrow band noise
- white noise
- pink noise
- fresh noise
Effective Masking
- interaural difference of 40 dB (earphones)
- interaural difference of 50 dB (inserts)
- just enough to occupy better ear
- threshold of better ear (non test ear) +10 dBHL
Under masking
-insufficient masking, the better ear is still contributing
Over masking
- excessive masking noise crosses over into test ear
- over estimates the hearing loss in the test ear
Plateau Method
- add masking, no shift in TE means threshold is accurate
- if threshold shift by 5 dB or more, increase masking by 10 dB and re establish, continue until stable
Occlusion effect in masking
- decrease (improvement) in BC thresholds at 1K or lower frequencies because of tightly fitting earphones
- seen only in normal listeners and sensorineural losses
Masking dilemma
- bilateral conductive hearing loss
- any attempt to mask the non test ear, bleeds into the test ear BC thresholds
What are the three main tests of balance testing?
- ENG/VNG
- Rotational chair testing
- Postural control
