what-when-how
In Depth Tutorials and Information
MANAG
EMENT OF HEARING LOS
S IN OI
TABLE 32.1
Results of stapedectomy in People With and
Without OI
The level of hearing loss in OI ranges from mild to
profound. The types of loss that can be present are con-
ductive, sensorineural and mixed-conductive and senso-
rineural. Management depends on the degree of hearing
loss present.
For mild hearing loss regardless of the cause, modi-
fication of one's listening environment may be all that
is necessary. Carrying on conversations in quieter sur-
roundings, paying more attention to the context and
facial movement, and moving closer to the speaker may
be adequate. For more severe loss, other options are
available.
Postop Air-
Bone Gap
<
10 dB
Postop
Sensorineural
Hearing Loss
Cases
OI SERIES
Garretsen and Cremers
46
58
85
9
Shea and Postma
58
62
75
8
Ferekidis
45
9
75
0
Vincent
47
23
85.7
0
NON-OI SERIES
Vincent
48
3050
94.2
0.5
Findings depict the number of cases, percent of patients with postoperation air-bone gap
of less than 10 dB HL and percent of patients with postoperation hearing loss.
BISPHOSPHONATES
Ossicular Problems
OI can cause deformity of the ossicles - either making
them thinner and fragile or making the stapes footplate
thicker and fixed in position.
44
Conductive hearing loss
can occur through either disruption of the ossicular chain
by fracture of the thinned ossicles or by obstruction of
sound transmission by fixation of the stapes footplate.
45
Postoperative complications of hearing loss are higher in
OI patients, with up to 8% losing hearing as compared
to 1% in the non-OI group.
45-48
Similar findings are
present in reconstruction of fractured ossicles in OI, but
comparative series are not available. The reasons for the
poorer results in OI are easily understood. The ossicles
are more fragile to any manipulation and less stable to
support any reconstruction. When the stapes footplate is
very vascular and thickened, visibility and fine manipu-
lation become more difficult. The safety margin between
the stapes footplate and the inner ear balance organs
(utricle and saccule) may be significantly narrowed to
less than 0.5 mm. Candidates for stapedectomy (
Table
32.1
) may also fail secondary to obliteration of the round
window membrane. Otosclerotic lesions of the round
window membrane are not always detectable by CT.
Improvements in success and safety have come about
through better prostheses, better lighting and magnifica-
tion and better instruments including the laser.
Bisphosphonates are being used to treat bone fra-
gility in most patients with OI. The impact of the
bony changes in the ear can have a potential effect on
hearing - either positive or negative. In one study it
was noted that patients with lower bone mineral den-
sity scores had a greater risk of a conductive hear-
ing loss.
8
Correction of this low density might prevent
such loss or even improve hearing. Limited research is
available examining the effects of bisphosphonates on
hearing loss in patients with OI and the research that
is available is retrospective in nature.
42
In one study of
42 people taking bisphosphonates, no change in hear-
ing was noted.
43
One retrospective study has reported
a lower than expected prevalence of hearing loss in a
sample of 36 patients with OI who were less than 20
years of age who had been treated with bisphospho-
nates for more than 2 years.
42
As present ongoing stud-
ies accumulate data and time, hopefully an answer to
the potential benefits will be found.
CO
NDUCTIVE HEARING LO
SS
Serous Otitis Media
When there is fluid in the middle ear, the ear drum
and ossicles cannot vibrate normally. This impedes
sound transmission to the inner ear causing a con-
ductive hearing loss. This is a common occurrence in
children but can occur at any age. Eustachian tube dys-
function, colds, allergies and ear infections are com-
mon causes. When treatment of the underlying cause
does not clear the fluid, ventilation tubes can be placed
to aerate the ear and drain the fluid. The incidence of
serous otitis may be greater in OI,
22
but the treatment
and outcome are the same.
BON
E-ANCHORED HEARING A
IDS
When a large conductive hearing loss is present, mid-
dle ear surgery is an option as reviewed above. When
middle ear surgery is not successful or when middle ear
surgery is declined, an option for treatment is a bone-
anchored hearing device. This is a hearing aid that is
attached to a titanium screw implanted in the skull.
