Chapter 40 - Otosclerosis Flashcards
Does otosclerosis involve the cochlea?
Rarely
Pathogenesis of otosclerosis
altered bony metabolism in otic capsule
ongoing resorption and deposition of disorganized bone
Results in fixation of ossicles
Normally, endochondral Ca complete by 1 yo in otic capsule
Bone becomes metabolically active, well-vascularized bone (spongiotic) or densely mineralized (sclerotic)
Contributing factors to otosclerosis
measles, autoimmunity, multiple endocrine abnormalities, low fluoride consumption
Can otosclerosis present with SNHL?
Rarely
Epidemiology otosclerosis
White female 10-40 yo (2:1 F-M)
How many patients have bilateral otosclerosis
80%
How many otosclerosis patients develop SNHL?
20-30%
Where does otosclerosis begin fixating the ossicles?
Anterior stapes footplate
Presentation of otosclerosis
Most common: adult-onset progressive CHL uni or bilat
Second most common sx: tinnitus
Hearing may improve in noisy environments (Paracusis of Willis)
Rarely have vestibular sx
Genetics of otosclerosis
AD, incomplete penetrance
How many cases of otosclerosis have a FHx?
50%
Schwartze sign
reddish hue seen through TM
Increased vascularity of bone over promontory
May be seen early, not always present
Otosclerosis audiogram
Worse at low frequencies
Carhart notch where bone conduction dips at 2000 Hz looking like a SNHL
Caused by inertia of ossicular chain
Acoustic immitance testing in otosclerosis
As tympanometry
Stapedial reflex present early but may be biphasic
As disease progresses, lose stapedial reflex
Which image is good at detecting otosclerosis
High Res CT
Non-surgical treatment of otosclerosis
hearing aid
can target osteoclasts with bisphosphonates, sodium fluoride, but neither are consistently recommended
Which ear to operate on if bilateral otosclerosis
poorer hearing ear first
If successful, the other ear 6 months later
Risks of stapes surgery
SNHL, vertigo, CN VII, taste, continued CHL, prosthesis extrusion/displacement, TM perf
Sx that often require revision stapes surgery
CHL, vertigo, SNHL, distorsion of sound
Do CT T bones prior to considering revision
How does revision surgery differ from initial stapes surgery in terms of success?
Decreased success, increased risk of SNHL
Lasers used for stapedotomy
CO2 (best at closing ABG)
Argon, KTP, Er-YAG
Two anatomical abnormalities making stapes surgery difficult
persistent stapedial artery- may ligate if necessary
overriding CN VII- retract gently
Can still do the operation
