EAR Flashcards
(28 cards)
Clinical presentation for [Treacher-Collins Syndrome] -4
- Mandibular hypOplasia
- Cleft Palate
- Auricular malformation (stenosis, atresia)
- Downward slanted palpebral fissures
This is Auto DOM
Function of Mid Ear MIS ossicle bones
Amplifies acoustic energy to overcome impedance mismatch between [air-filled EAM] and [fluid-filled inner ear]
Name the 2 Mid Ear muscles; Innervation? ; What is their Function?
⬇︎ transmission to inner ear to protect cochlea AND reduce low freq background noise
Stapes: = Facial CN7
Tensor Tympani = [Trigeminal CN5B3]
What is the purpose of EPAT-2? What happens when it is dysfunctional?
EPAT (Eustacian Pharyngotympanic Acoustic Tube) drains and aerates Mid ear ; Plugged up sensation and Popping that eventually –> Otitis Media
Describe the tortuous path of Facial CN7 thru the temporal bone (5 steps)
1st: Exits Internal Auditory canal into inner ear
2nd: Travels SuperoLateral to Cochlea and then angles down sharply to make “hairpin” bend and articulate Geniculate ganglion which = first genu
3rd: travels along medial wall of tympanic cavity above OV window and below lateral semicircular canal
4th: Drops inferiorly which = second genu
5th: exits at Stylomastoid Foramen
Why are both CT and MRI needed for Facial CN7 w/u during ear disease
- CT demonstrates integrity of the osseous Facial CN7 canal
- MRI reveales Facial CN7 itself
What is Perilymph? What is Endolymph? How are they different?
Perilymph = fluid in osseous labyrinth (which surrounds membranous labyrinth) = High in Na+ (similar to extracell fluid)
Endolymph = fluid in membranous labyrinth = High in K+ (similar to intracell fluid)
This electrochemical difference –> +80 mV gradient across membranous labyrinth that allows acoustic energy to = neural impulse
Where is Perilymph and Endolymph found in relation to Basilar Membrane Of Organ of Corti
Perilymph = Below BM
Endolymph = Above BM
Basilar Membrane is responsible for tonotopic frequency of Cochlea
What is the “traveling wave”
Movement of BM in response to sound -
- High frequencies displace BM near cochlear base
- low frequencies displace BM apex
Note: [Inner haircells = Affarent] vs [Outer haircells = Efferent]
How is sound transduced (simulate cochlear hair cells)
Sound, via shear force, moves tectorial and basilar membrane –> moves sterocilia –> opens/closes ion channels–>receptor potential in inner haircell –> Affarent action potential
What are the Utricle and Saccule
- Utricle = detects Horizontal acceleration
- Saccule (I’ll Sacc U Vertically) = detects Vertical acceleration
These are Vestibular organs
Superior Canal Dehiscence Syndrome etx; Sx-3 ; Dx
Idiopathic Absence of bone over the Anterior Semicircular canal; [High Res CT]
- Sound vs Pressure-induced vertigo
- Conductive hearing loss
- Autophony (perceiving own’s voice/sounds to be loud)
Starting with Auditory n., what is the pathway to the brain for sound and balance? -6
Auditory n.–>Cochlear nc. –>[SUP olivary complex]–>Lateral Lemniscus–>Inferior colliculi –> medial geniculate –> [Area 41 Heschl’s gyrus]
What’s the max amount of decibel loss in Conductive Hearing Loss?
60 dB (anything >50 = ossicular damage is cause)
What things should specifically be included in Hearing Loss History -8
- Laterality
- Duration
- [Severity & Progression]
- Asc. factors (otalgia/otorrhea/tinnitus/vertigo/aural fullness)
- Meds & Surgery
- Head trauma
- Fam Hx
- Autoimmune Dz
Air-Bone Gap on Audiogram indicates what type of hearing loss-2? What is Air-Bone Gap?
Conductive or Mixed; Air is blocked, but Bone still conducts sound waves during vibratory part of audiogram–>bypasses external/mid ear obstruction
On Tympanogram…What do these results indicate:
⬆︎Compliance of TM
⬇︎Compliance of TM
Poor Compliance of TM-2
- [⬆︎Compliance Type Ad] = MIS ossicle bone disengagement
- [⬇︎Compliance Type As] = Otosclerosis
- Poor Compliance (Type B) = Tympanic Perforation vs Mid ear effusion
What is the most common finding on imaging for children with Sensorineural hearing loss
Enlargement of the Vestibular Aqueduct
Describe how to perform Weber test and How you interpret it?
1st: Ask Which Ear is deaf? - Pt says RIGHT ear is deaf
2nd: Strike Fork on Mid head
If Fork is heard louder in RIGHT = CHL of RIGHT
vs
If Fork is heard louder in Left = Sensiorineural Hearing loss of RIGHT
Conduction Hearing Loss Concurs in Laterality (if Pt reports deaf on R, tuning fork is louder on the R)
Otosclerosis etx
Fixation of Stapes in OV window –> uni vs BL Conductive hearing loss
Otosclerosis dx and tx-2
dx: Carhart notch = 10-15 dB ⬇︎ in bone conduction @ 2000Hz
Tx = Hearing Aids vs Stapedectomy
4 Main causes of Conductive Hearing loss
check for ITEO!
Impaction of EAC (cerumen vs foreign object)
Tympanic Membrane Perforation
Effusion of Mid Ear
Otosclerosis
How can Superior Semicircular Canal Dehiscence cause Hearing loss; Sx?
Dehiscence can –> Fistula between SUP Semicircular canal & Dura –> 3rd window into inner ear–>
- Tullio sign (Dizziness from sound/pressure)
- Hennebert sign (Dizziness from Valsalva or Pneumatic otoscopy)
- CHL
