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Abstract
Otosclerosis is a common disease and
presents in young patients with a 2:1 female:
male ratio. It’s bilateral in up to 85% of
patients, but often asymmetric. The disease
occurs more frequently between 20-40 years
of age, and is known to worsen during
pregnancy.
Otosclerosis occurs when the dense, ivory like
endochondral bone is replaced by spongy,
highly vascular, irregular foci of haversian
bony tissue.
Histologically, otospongiosis is characterized
by the enlargement of perivascular spaces,
osteoclastic bone resorption, and new
immature bone formation.
The slight variation in the different imaging
techniques might be another cause for the
presence of false negative results as using CT
scan with 1 or 2 or even 5 mm thickness.
CT has better advantages over MRI in
detecting otospongiotic focus, abnormal
course of the facial nerve, solid or
Summary
90
obliterated footplate of stapes, perilymph
gusher, cochlear otosclerosis and site of
prothesis.
MR imaging may be helpful for understanding
the mechanism of SNHL and may reveal
complementary findings to those on CT scans
as suppurative labyrinthitis, reparative
granuloma and perilymphatic fistula.
MR imaging allows an early diagnosis of
suppurative labyrinthitis and reparative
granuloma ( results from individual patient
immunologic sensitivity to various surgical
materials or simple surgical trauma to the
mucoperiosteum of the middle ear) which
could be the cause of unexplained SNHL
following surgery and can predict intracranial
complications, such as meningitis, sigmoid
sinus thrombosis, and temporal lobe abscess
(due to extension of the suppurative process
into the internal auditory meatus along the
acousticofacial bundles).
CT scan and MRI can show us some findings
preoperatively as:
• Spongiotic changes.
• Oval window changes.
• Cochlear otosclerosis.
• Dehiscent facial nerve canal.
• Fixed malleus.
• Obliterative otosclerosis.
• Persistent stapedial artery.
• Perilymph gusher.
• Other pathologies that mimic
otosclerosis as osteogenesis
imperfecta, osteopetrosis and
syphilis.
While imaging can guide us to the cause of
postoperative complications and can show:
• Site of prothesis: slipped, intra
vestibular bulging.
• Perilymph fistula.
• Intravestibular granuloma.
• Labyrinthine hemorrhage.
• Regrowth of otospongiotic
focus.
• Incus necrosis.
In our study we used a systematic
review study of 7 articles chosen from 43
articles and abstracts.
CT scan can detect preoperative problems as
facial nerve anomalies that might be
encountered during surgery, detection of
possible causes of perilymph gusher, persistent
stapedial artery, obliterative otosclerosis and
cochlear otosclerosis with a high sensitivity
rate (94%).
The value of CT scan in detecting the site of
the prothesis is high; however detection of
different causes of postoperative SNHL and
vertigo can not be accurately elicited due to
insufficient number of studies.
MRI can detect reparative granuloma,
perilymph fistula and suppurative labyrinthitis
which could be the cause of the postoperative
SNHL and vertigo.
from the previous findings we recommend
that more studies have to be done regarding
the value of CT scan and MRI on explaining
the causes of postoperative complication due
to insufficient number of published articles, on
the contrary we recommend the use of
preoperative CT scan for proper assessment
for otosclerosis.