The next talk is going to be on the
common pathology of the temporal bone
and we're gonna step through some of the
common things. We'll first talk about
technique so you know I was always
trained by my old mentor Tony Mancuso is
every time you give a talk, talk a little
bit about the technique and just to
indicate to the audience that the images
that we're showing are not voodoo
anybody can replicate these just by
doing what we--acquiring them the
same way that we do so for the temporal
bone studies you'll be able to replicate
everything that we do if you follow
these principles and that is multi
detector imaging obviously everyone's
doing that.  Again, 0.625
especially for the temporal bone at
least now I think in 2006 is helpful
when a few years ago we would say one point--you know--1.5 or
1.25 was sufficient but I
think really now in 2006 especially now
that we've lowered our dose, 0.625 I
think is appropriate.  Direct axial and
this is where it's a little bit
different I just want to take a show of
hands for your temporal bone for people
doing temporal bone CTs how many
people are doing axials with coronal
reformats and then how many people are
doing direct axials and direct coronals?
Yeah so I agree I think right now we
really have switched over to coronal
reformats
in adults and children and we always
magnify each side to about a 9
centimeter field of view so you know--there's a--you know one of my favorite
sayings was Mark Twain right?  "Good
judgment comes from experience and
experience comes from bad judgment."
Unfortunately I have experience so this
is from my experience if you will so
this was an older study it was actually the
first temporal bone study I ever read at
University of North Carolina so I had
come just finished my fellowship at
University of Florida and it's amazing
you know I think I was the smartest
I ever was when I was finishing my
fellowship because I knew all the
answers right?  And I think it's been a
steady downhill progression since then
so I was coming out of my fellowship I
knew everything and--but I was new to the
place and I was always taught a very
specific way to image a temporal bone.  So
I was recruited actually to UNC in part
by the head neck surgeon
there.  So we went to a tumor board they
showed me this temple bone and I
said you know I don't--I'm the new person
I don't want to make too many changes
and because I'm really smart right
because I'm super smart I don't need all
that fancy stuff that I've learned in my
fellowship because that stuff was--you
know--dumb people need that I'm smart
right?  So they showed me this case
and you know I said well there's a
little bit of soft tissue thickening
here in the tympanic membrane excuse me
in the in the middle ear cavity.  The
ossicles there they look fine to me
and I think this must be mucosal thickening so
this ENT surgeon who's a head of ENT
then and now put his arm around me and
said well there was a huge Cholesteatoma
it eroded the tegmen tympani the ossicles
were eroded and he said well Suresh
don't feel bad because you can't see
ossicles on CT anyway we know that so I
kind of got pissed off and then I
went and changed all the temporal bone
CTS that we do so technique number one
is that and I get asked this a lot when
I'm in the reading room we'll do a head
and neck study and they'll say well
excuse me we'll do a regular brain study
and they'll say well what do you think
about that thing in the palate or what
do you think about that thing in the ear
and I said look I've learned over time
that if you really want to be accurate
and be right don't try to read detailed
images on the side on the edge of a
brain MR because you're going to be
wrong more times than you're right
and I have to tell you know in my role
now as an administrator and as a
chairperson well you have to become a
little bit more facile about pre
authorizations and be wary about
bringing patients back I don't think
we've been denied bringing a patient
back that had a brain MR in order for a
dedicated skull base MR so we haven't
run into that.  Joe I don't think
we've had any problems have you?  Yeah so
at least I'm not a huge fan of the
insurance companies but by the same
token at times that they do make the
right decision so when you do do these
change of techniques this is what you
should be seeing so all of a sudden once
you see it now you can see the apical in
the middle turn of the of the cochlea
you can see the moti olace the base of
the cochlear canal the internal auditory
canal the vestibule the anterior and
posterior crus to the stapes this is
the manubrium and the malleus
excuse me and the lenticular process
of the incus.  So this year we didn't--
often times I guess every other year I
often times just step through the normal
anatomy of the temporal bone we didn't
do that this year but next year if you
come back we can do that so if you're
not as familiar with this anatomy you
know come back next year or something
like that and I want to ask this
question because I see in the audience
like a lot of familiar faces how many of
you are here for the first time
and how many are repeaters that have
been here before?
Wow so it's about 50/50 well welcome
back and thank you I appreciate it and how
many you are going to come back in the
future?  Alright that's great yeah just
as an FYI I don't make a cent off of
this I mean honestly I do it just
because I like to do it so there's
nothing lining my pocket from you guys
showing up so you know it's great to
have you.  Now when I grew up in the in
the the last century if you will I did
my residency at the Brigham and I went
over to Mass Eye & Ear and the way that we
interpreted the temporal bones at the time
was doing something called conventional
tomography and you know radiologists we
don't get older we get more experienced
right?  So are there any
experienced radiologists
in the audience?  Right okay that remember
conventional tomography right?
Remember those days?
Somebody just laughed right it's painful
right you want to eliminate those days
but in the theme of what's old is what's
new what's new is what's old these were
the views that the Poschl and the
Stenvers view were the views that we
used to do on conventional tomography to
end up looking at the middle ear cavity
and then I thought I was done with it
then lo and behold they returned it's
like everybody watches what--
The Walking Dead?  With the zombies that come
alive you thought they're dead and they
come back right?  It's just like The Walking Dead for me.  So the
Poschl and the Stenvers views are back
so with the ability to perform
multiplanar reconstructions we now
routinely perform these old postulant
Stenvers view the Poschl view was
taken in the plane parallel to the
superior semicircular canal and the
Stenvers view is perpendicular to the
superior semicircular canal and we do
this in particular to look for superior
semicircular canal dehiscence so it's a
very topical
issue in fact one of the most common
reasons we do do temporal bone CTs at
our shop is to look for superior
semicircular canal dehiscence.  So what
about for MR I think this is--everyone's
doing this--you know full course of the
cranial nerve eight slice thickness
should not exceed three millimeters and
in our three tests that we're doing at
two millimeters.  Pre contrast T1
don't forget that by the way because
there's certain pathologies that you can
miss if you don't do the pre contrast T1 especially trying to figure out that
and the petrous apex versus a cholesterol
granuloma sometimes that can be a little
tricky.
And remember other things beside
vestibular schwannoma can cause hearing
loss we have to remember things like
multiple sclerosis as well.  We're now
doing routinely the high-resolution
heavily T2-weighted images you can call
it drive you can call it cyst you can call
it fiesta choose whatever you want to
but we're routinely getting this at our
institution and when you see this
you really do get some glorious detail
by looking at the modiolus you can see
all four nerves of the inner ear and you
can see all four nerves within the inner
ear and i'll show this a little bit
later also you can do these very nice
reconstructions where you can see the
crista falciformis here you can see the
cochlea the superior lateral
semicircular canals the vestibule is
really very detailed imaging so the
anatomy now remember in the inner ear
there are four nerves that run in the
internal auditory canal and so the top
nerve here is the--what--the seventh nerve
and here is the seventh nerve right here
there's our seventh nerve here and right
posterior to the seventh nerve this
nerve right here is what that's the
superior vestibular nerve so this is the
whole concept of 7up remember the whole
7up thing with the seventh nerve up and
then below the seventh nerve is the
cochlear nerve so this is Coke down so
remember the 7up Coke down concept so
the seventh nerve was anterior and
superior and the cochlear nerve is
anterior and inferior and then posteriorly is the inferior vestibular nerve
here so when you look at this
parasagittal view and this really should
be routine just to orient ourselves
here's posterior
and this is anterior so here's our
facial nerve and here's our cochlear
nerve superior vestibular nerve and the
inferior vestibular nerve so if you do
the heavily weighted T2-weighted images
you should be seeing this and this is
routine on our IACs now I remember
when the CIS imaging first came out it
would take us about I think six or seven
minutes to do it now with the
advancements and MR they take about two
and a half minutes to do it and
certainly I think it's very
helpful you can see all four nerves but
also you can see vestibular schwannomas
without giving contrast and again back
in the late 80s excuse me in the late
90s when this was first developed some
authors were saying we don't even need
to give gadolinium for internal
auditory canal MRs to look for
vestibular schwannomas and I think that's
right in fact we tried to do a
discounted limited MR just to look for
vestibular schwannomas but it wasn't
really fully accepted by our ENT
surgeons because their view was you know
if we're going to spend X amount of
money to do it you know I want the full
monty you know I want to be able to see
if there's any enhancement--dural
enhancement if I want to look for
several areas of enhancement involving
the facial nerve I'm going to look for
enhancement involving the cochlear the
vestibule to look for labyrinthitis
which we'll talk about later so they
didn't really gain a lot of traction
but having said that here's a typical
appearance of a vestibular schwannoma
but you know in certain days
when you're really busy it's potential
you can miss this little enhancement
right here involved in the internal
auditory canal so if you do do the
heavily T2-weighted images just realize
you can--sometimes I think the
high-resolution imaging is actually more
accurate than actually giving the
contrast to look for vestibular
schwannoma so I really have found these
beneficial.  The other thing that I've
learned in my residency which I was wrong
was that back when I grew up again they
say that vestibular schwannomas used to
arise right here at the porus acusticus
and there was something called I think
it was the Obermeyer-Steiner line or
something like that.  Obersteiner-Redlich
Line--yeah thanks--Obersteiner-Redlich
line and it felt that this was a
transition between myelinated and
unmyelinated nerve
right and it was felt to be unstable if
you will and that's where vestibular
schwannomas
arose from and again I think it was back
from the days of conventional tomography
when the only way we can make this
diagnosis was to look for expansion of
porus acusticus right?  Well in actuality we
see now that the vestibular schwannoma
is the least that I see in the early
stage arrives in the internal auditory
canal and the spread pattern at least
the way I've interpreted is they tend to
get larger and larger and they grow more
towards the brainstem and then once they
get out of the porus acusticus they do
kind of explode like an ice-cream
cone if you will so just realize when
you are looking for vestibular
schwannomas make sure to pay particular
attention in the fundus of the internal
auditory canal.  Well this was the way
that we learned anatomy the cochlea back in medical school we had an apical
middle and basal turn in the textbooks
we learned about the inner scalar
septum which was the bone that looked
like this we also learned about the
basilar membrane and we also learned
about the organ of Corti and you know lo
and behold I never would have imagined
this is Shutnik's anatomy on the right
Shutnik did the famous anatomic--famous
pathologic sections through the inner
ear and this is what we can see
clinically now so when you look at this
you can see the apical--and this is
actually the the middle and the apical
turn of the cochlea but you can see the
inner scalar septum which is the black
here this correlates very nicely to the
anatomy and you can see this line right
here that's actually the basilar
membrane so now even the internal
structures of the cochlea can be seen
very elegantly we haven't gotten down in
the organ of Corti yet but occasionally
I have been to talks where you may be
able to see the scala media as well.  Well when we
look in the inner ear as well this is
how we learned about things in medical
school there was actually a macula of
the utricle and now when we do our MR we
can now see if you look very closely, if
you look in the vestibule you'll see this
little smudgy area here now when I first
saw that this was shown to me by Jon
Castleman about 10 years ago I thought
it was artifact but you know over time
what I've done I came back and looked at
what we did and turns out yes this is
actually the
macula of the utricle so we can actually
look inside not only the vestibule but
if you go back to here the
vestibule is actually formed by the
saccule and utricle so now we can
actually look inside the utricle and see
the macula that's sensory epithelium
that allows us to have balance so for me
it's really amazing where we've come
over the last few years.  Now let's see if this is gonna work for me or not.  No, it's not working but that's okay.
One of the things to look for when we're looking at the middle ear is that anytime that
you have a patient with unilateral
serous otitis media and again remember
you know from my stand point the brain
is an accessory organ of the neck you
know as is the chest the abdomen and the
arms essentially right?  But some people
feel that the neck is not as important
as other structures a little bit further
north so when you are looking at the
brain remember to look at the skull base
and if you see in the skull base if you
see this unilateral mucosal thickening
involving the mastoid air cells make
sure that you start looking in the nasal
pharynx because if you look in the nasal
pharynx occasionally you will pick up
these patients that have nasopharyngeal
carcinoma is because the nasopharyngeal
carcinoma is will obstruct the
eustachian tube and when they have
struck the eustachian tube then you'll
end up having this mucosal thickening
and from a medical legal standpoint I
can tell you I have seen a few cases
where this has potentially turned into
an issue so one of the things I always
recommend when you're looking at the
brain I always look at the top and the
bottom look at the very top but also
look at the very bottom make sure you
look below the skull base.  Ok let's talk
a little bit about some of the pathology
so the first thing that we'll talk about
is the Z's that's called otosclerosis
now how many of you have heard of
otosclerosis?
Most of you.  All right so oldest grossest it's
really it's it's I would characterize it
as a unique disease of the ODA capsule
and no one really knows what the
etiology is it is primarily an autosomal
dominant with incomplete penetrance it's
a little bit more common in females and
males and it's due to abnormal
resorption and deposition of bone in the
middle ear.  It still is a clinical
diagnosis but I say that with
a little bit of trepidation because I'm
gonna show you the characteristic
findings of otosclerosis and clinically
our ENT colleagues or otologist will say
well you know that's not really
otosclerosis what you're seeing because
we make the diagnosis based on audiology
well I'm not a hundred percent sure on
this because our imaging has gotten so good
that we're starting to look at early
depositions as you'll see a resorption
of the bone so I actually think sort of
similar to the cranial nerve and the
perineural involvement years ago when we
would say this we would get poo-pooed
and say yeah you really can't see
cranial nerve involvement just like that
my old colleague at UNC said we can't
see ossicles on CT I'm really coming to
the conclusion that we can see
otosclerosis before the findings are
present audiologically with the classic
findings so when we look at otosclerosis--
again anatomy is so important right here
so I'll take a little bit of time to go
over the anatomy so here's the internal
auditory canal here is the middle turn
of the cochlea here's our vestibule
right here and this is the ice cream
cone right here's a head of the malleus
and the short process the incus and this
back here is a sign of symphony.  The key
thing to look for otosclerosis is that
if you look at the oval window so here's
the oval window and the most anterior
aspect of the oval window has a specific
name to it.  Anybody remember the
name?  What was it?
Yeah it's called a fissula ante fenestram.
This is the fissula ante fenestram
and in this area here you can see some
rarefaction of bone so if you are
looking for otosclerosis the first
thing that you have to look for is look
right here at the fissula ante fenestram
because that's the earliest sign so
histologically this is what Shutnik
identified so here is our oval window
and right here at this bone right here
this is the fissula ante fenestram
and this is what this looks like
histologically and this is what we see
on CT scan.  Now because this is occurring
at the oval window if I'm--correct me if
I'm wrong but none of you are Latin
scholars anyway for pete's sake but
remember I think window in Latin is
fenestram and so this is why this is
called fenestral otosclerosis
now if you have otosclerosis and you
have it behind the window this is what's
referred to as retrofenestral otosclerosis so in this particular case we
can see all of this rarefaction of
bones surrounding the dense bones
surrounding the cochlea.  So this is
behind the oval window and this is why
this is called retrofenestral otosclerosis. 
Occasionally you can see
cochlear enhancement and again for those
of you that have read about otosclerosis
there was something called a Schwartz
sign where the surgeon--otologists
could look in and see this blue haziness
involving the cochlea.  I'm not sure how
accurate that is--Can you guys see that? 
 The surgeons in the back have
you ever seen a Schwartz sign before?  No? 
 Even when I talk to the otologist the
attendings I haven't seen that before
but anyway the reason why you used to
get--or it was the Schwartz sign was
described is that you would get a little
bit of hyperemia involving this bone
along the cochlear promontory but this
is the radiological correlate.  Everybody
see this little rarefaction of bone
surrounding the cochlea so that's what
we mean by peri cochlear lucencies
and if you do your MR just right this is
kind of--I very rarely see this, this is pre
contrast and post contrast.  This is
diffuse enhancement involving the
cochlea.  So one thing that I always have
to caution myself is that as I'm looking
through the films I look at internal
auditory canal MRIs you know I'm looking
for vestibular schwannomas right that's
number one I'm looking for dural
enhancement that's number two but I
always have to pay attention to the
cochlea because remember patients that
have hearing loss often have dizziness
often have vertigo and one of the causes
can be otosclerosis
and if you're doing an MR for patients
with vertigo and dizziness remember they
still could have otosclerosis and you
have to look for that enhancement
involving the inner ear.  Now this is one
thing that has come up a little bit more
recently and that's the whole concept of
the third window so we'll look at a CT
scan and we'll see that middle turn in
the apical turn and we'll look for the
typical findings of otosclerosis and we
may not see it here involving the fissula
but if you look at the internal auditor--or ear canal
sometimes you'll see the smudginess of the bone or sometimes you'll
just see frank cavitation that looks
like this and this was always a head
scratcher because I looked at this and I
wasn't quite sure but it turns out that
this was described by Shutnik back in
the 1950s and this is actually the third
window this is also otosclerosis so not
only can you get otosclerosis involving
the oval window the fenestral or the
retro fenestral but you can also get
it adjacent to the internal auditory
canal so this is the whole concept of
the third window.  Any questions so far?
You with me?  Alright okay what I'm now
going to talk about are the inner ear
malformations and what I'm going to do
is I'm going to tell you the classical
approach.  Now I'm well aware now that we
have more information about specific
genetic mutations and their newer
classifications that have come out IP1
IP2 IP3 I think in itself those are
somewhat controversy.  I'm not a
completely accepted these but what
I'm going to do is tell you about the
classic inner ear malformations because
like I mentioned before--those
of you that took the boards I was a
little panic when I took my boards right
and so I said to one of my attendings I
said you know what if they show
me a weird inner ear and said if they
show you a weird inner ear just say Mondini and go to the next case right?
Just get rid of it right?  Well not
everything is a Mondini malformation
so what I want to do is show you an
approach and it's really based on the
embryology because you know head and
neck radiology for me is
fa--obviously I love what I do right I
think it's the greatest thing in the
world but you also have to realize that
you have to know a little bit of
spectroscopy and molecular imaging in
these days.  You have to know anatomy but
you also have to remember a little bit
of embryology and if you understand the
embryology of how the inner ear develops
then you'll be able to understand the
inner ear malformations.  So the way the
inner ear develops is that there is the
creation of this structure here which is
the otic vesicle and over time the
otic vesicle start to differentiate so
you have this area--eventually this area
becomes a cochlea, this area becomes the
vestibule and the--excuse me--well the
utricle and the saccule and these areas differentiated
this semicircular canal.  So the type of
inner ear malformation that you're going
to see is going to depend on where the
arrest occurs in embryogenesis.  So the
first thing is that if you have no
formation of an otic vesicle--and this is
rare--you're going to have what's
referred to as the Michelle's Anomaly
and these are very rare in fact the
first case I ever showed Doug gave it to me
about 20 years ago.  I hope you remember you
gave me a case of Michelle's and I used
it up until the point I got this case.
This is a nice example but a Michelle's
Anomaly is essentially--there's the otic
vesicle is not formed and all you have
is formation of the ossicles and like
sort of Doug said you've seen one you
may never see another one but this is a
Michelle's Anomaly and this is what it
normally looks like so this is the
cochlea this is the vestibule this is
what you should normally see and here's
the inner ear structures but in this
case we can just see the ossicles
without any inner ear so that's
a Michelle's.
Now if you have formation of the otic
vesicle and then you have an arrest you
can see this looks like a blob right?  It
kind of looks like a blob.  Well this is
what I refer to as a common cavity
malformation because the common cavity
is the otic vesicle is formed and then
you have your arrest so this is what it
looks like in the inner ear.  Literally it
just looks like a water balloon so you
have a water balloon in the inner ear
there's no cochlea there's no vestibule
there's no nothing and this is what's
referred to as a common cavity.  Now if
you have continued development and then
you have an arrest now you have a little
bit of formation of the cochlea and you
have some formation of the vestibule and
some formation of the semicircular
canals.  Because the cochlea is not
completely formed this is what we refer
to as cochlear hypoplasia so as I showed
you before you know this looked like a
blob so what do you think this is going
to look like?  This is not going to look
as blob-ish it's probably going to have
a little bit more separation into the
vestigial vestibule and cochlea but clearly
it's not going to be as clearly formed
as as the normal ear so this is a little
bit very early and if there's a little
bit more differentiation.  This is still a deformed
cochlea so this is what we would expect
to see and this is what we see
radiologically so what we see here is
the middle ear cavity--there's our
ice-cream cone anteriorly is the cochlea
and posteriorly is the vestibule so with
a leap of faith you can kind of see
how this is the vestibule and this is
the cochlea.  Similarly a little bit more
advanced here's a little bit of the
cochlea and here's a little bit of the
vestibule so it clearly doesn't look as
created or as detailed as what we will
see but clearly there's more
separation here than we saw when we just
have the otic vesicle.  Now what if we
have a little bit more formation and
then we have an arrest and this is when
we get into the Mondini malformation.  Now
one of the reasons we don't see cochlear
hypoplasia very much or the Michelle's
very much is that these are early
development in the fetus and sometimes
the fetus--it doesn't make it and
fortunately it's aborted and it turns
into a miscarriage.  The thing is the
Mondini malformation really is the latest
development just before the the fetus
becomes viable so that's why we tend to
see more Mondini malformations than
anything else.
So what a Mondini malformation is
fusion of the apical in the middle turns
with a normally formed basilar turn.  Now
everyone's heard of Mondini right?  So you know how--who Mondini was
or how he described this?  I find this
fascinating.
So Mondini was--you know--described
this before the days of CT and MR
obviously and he described it in a
two-year-old that was run over by a
wagon back in the late 1880s.  So the
child was run over by a wagon developed
this bad sepsis and then died.
Now Mondini knew this kid and this
kid was congenitally deaf his whole life
in fact it was bilateral so essentially
because he knew the family he ended
up doing a necropsy on the child after
he died.  So that's how Mondini first--
that's why it's called a Mondini
malformation and so what he actually
described was a fusion of the apical and
middle turns with the normally formed
basilar turn.  That is the definition
of a true Mondini malformation.  So this
is the histologic section there is a
basilar turn with fusion of the apical
and the middle turns and then what we
see here is there's our fusion of the
apical in the middle turns with a
normally formed basilar turn.  Now what
Mondini described was what was
something else.  Do you know what we're
looking--anybody want to guess what we're
looking at right here?  Yeah any idea what
that is?  Yeah that's a vestibular
aqueduct and we'll talk about the
vestibular aqueduct because what Mondini
actually described was this disease
entity.  So the vestibular aqueduct is
located along the posterior margin of
the temporal bone and this is the
endolymphatic sac that runs in the
vestibular aqueduct and you can have
this disease entity which is enlarged
vestibular aqueduct and if you see a kid
with an enlarged vestibular aqueduct pay
close attention to the cochlea because
nine times out of ten you're going to
have an abnormality involving the
cochlea as well and that's actually what
Mondini described.  Mondini described
fusion of the apical and middle turns
and he also described an enlarged
vestibular aqueduct.  So those of you that
are head and neck people out there, there is
this entity of enlarged vestibular
aqueduct.  This is actually what Mondini
described so when we talk about a
Mondini malformation we kind of focus
on the cochlea but in actuality he
described this entity where the cochlea
is malformed but also the vestibular
aqueduct is malformed so the point is if
you see something that looks like the
cochlea is abnormal take a look at the
posterior aspect of the petrous bone. 
Similarly if you see an abnormality
involving the vestibular aqueduct take a
close look at the cochlea as well too.  So
this is the enlarged vestibular aqueduct. 
There is a fusion the apical in the
middle turns and you can also make the
diagnosis on MR.  So here's our cochlea
and here's the enlarged vestibular
aqueduct seen on MR.  And again when
we're ramming through our IAC MR
studies again we're looking for
vestibular schwannomas but remember look
for that cochlear enhancement and then
also--look on the T2-weighted images--look
for enlargement of the vestibular
aqueduct as well.
Alright the next thing that we'll talk
about is labyrinthitis.  So what
exactly is labyrinthitis?  Labyrinthitis
it's pure and simply it's just an
infection of the inner ear right?  And it
can be caused by either the type of germ
that causes it so it can be bacterial,
viral, syphilitic, fungal, toxic, or
autoimmune or it can be caused by the
route of spread.  So it can be due to a
middle ear infection,
meningitis, blood-borne, or
post-traumatic.  So what exactly is
labyrinthitis?  What it is is that it--
acute labyrinthitis is essentially when
you have pus in the cochlea.  So what
happens in acute labyrinthitis it's just
like anyplace else in the body.  Any time
that you have pus
you're going to elicit some type of
inflammatory response so an acute
labyrinthitis involved in the inner ear
is when you have pus involved in the
inner ear and then when you give
contrast you can see this enhancement of
the cochlea compared to the opposite
side and in this case we can actually
identify the cause of the labyrinthitis
and this is due to an infection
involving the middle ear so this is what
we would refer to as tympanogenic
cause of labyrinthitis because of this
direct effect.  But on the other hand if
we have a labyrinthitis that's chronic--it's been there for a while--the way the
body responds to this acute infection
that's not treated is it lays down its
version of a scar.  So for instance if you
have a cut and you keep cutting yourself
eventually it's not going to heal itself
you're going to develop a scar and
that's the way to think of this disease
entity which is obliterative
labyrinthitis or labyrinthitis ossificans. 
Essentially it's an infection
involving the inner ear that was never
treated and eventually what happens, you
develop this deposition of this fibro
osseous material into the channels of
the cochlea.  So in this particular case
we can see the inner ear--excuse me--the
internal auditory canal.  Here's our
petrous bone and this we can see the
ghost if you will of the cochlea and
with a leap of faith you can see a
little bone right here that's been
deposited in the cochlea corresponding
what we would expect
see on the packs of pathologic sections
that Shutnik described many years
ago.  So that if you will is the chronic
labyrinthitis.  We can diagnose this with
CT or we can diagnose this with MR so
again the other thing to look for when
you're looking at your MRs in patients
with hearing loss is make sure you look
at the fluid within the inner ear
because that fluid should be nice and
bright.  If you don't see the bright fluid
that tells you we have something
replacing the cochlea as well too so
that's labyrinthitis ossificans.  And next
we're gonna finish up with cholesteatoma.
Now cholesteatoma is probably the most
common reason you're performing a
temporal bone CT right?  You probably see
it every single day.  So what I want to do
is go over the pathogenesis of cholesteatoma.  These other things like the
inner ear malformations and otosclerosis
and the labyrinthitis you may
occasionally see it in a general
practice, but cholesteatoma is something
that you will definitely see.  So you know
this was the definition of cholesteatoma
it's keratinizing debris that arises
from the desquamation of the squamous
epithelial lining--I have no idea what
that mean, I have no clue, I really don't.
But it kind of--Doug said this before, the
way I think of cholesteatoma is skin
growing in the wrong place.  So what I
want to do is talk a little bit about
where these cholesteatoma
are.  So cholesteatoma occur in two
flavors: there's an acquired cholesteatoma
and there's a congenital cholesteatoma
and this is the pearly white mass that's
been described so in a in a child or an
adult that's never had significant ear
disease the surgeons can look and the
otologist can look in the external
auditory canal and they can see the
pearly white mass and if they're really
lucky sometimes they can see these
bubbles that actually arise from
the tympanic membrane.  Now I don't know--
do you guys--the surgeons--have you ever
seen the bubbles in cholesteatoma?  Of the
tympanic membrane?  Is that yes or no?  No?
No okay yeah, I don't know but some
people tell me they can see the little
bubbling of the
tympanic membrane but the pearly white mass
is the classic finding.  So how do we make
the diagnosis of congenital
cholesteatoma?  Well first of all there
has to be no history of a prior ear
infection--that is really really
important.  There has--there can be no history
of prior ear infection and then when we
look in the middle ear we can see this
focal soft tissue mass that tends to be
close but really separate from the
cochlear promontory because if you did
see a mass right here on the cochlear
promontory that was red, then what
diagnosis would you think about?  Yeah,
glomus tympanicum tumor, right.  But and
if you see a pearly white mass in this
location then you're thinking about
congenital cholesteatoma but notice the
mastoid ear cells--see how they're well
aerated?  They look pristine.  So the
surgeons look in, they see a pearly white
mass and a kid.  The mastoid air cells
look well aerated.  This is the diagnosis
of congenital cholesteatoma.  Now this is a
very large congenital cholesteatoma,
sometimes it can be called an epidermoid.
Some people have advocated doing
diffusion imaging just to confirm the
diagnosis, I assume it can be helpful
when it's this big but in general I
think you can make this diagnosis from
across the room.  But acquired
cholesteatoma is something completely
different.  So an acquired cholesteatoma
is due to chronic ear disease and the
chronic ear disease is felt to result in
obstruction of the eustachian tube so
you know what you've probably had this
before when you fly and you land what
happens to your ears, they get what?
 Blocked up and so what do you end up
doing in order to open your ears?  Do it like this
right?  So what you're doing is actually
you're trying to open that eustachian
tube and you're trying to open that
channel between the back of your throat and
the middle ear cavity.  So normally what
happens is that you have junk and
basically it's all of the squamous
epithelial cells that normally exit your
ear.  You usually go that way right?  And
the reason they go that way is that the
opening between the back of your throat
the middle ear is patent and essentially
all the vectors are pushing all this
junk out of your ear but if you have
eustachian tube dysfunction what ends up
happening?  You have a reversal and all of 
the stuff, all of the pressure is now
heading this way.
So as a result this causes retraction of
the tympanic membrane.  Now there are two
parts of the tympanic membrane: there's a
pars tensa which is a tense part and
anybody remember the second part?
Pars flaccida, exactly right.  And the pars flaccida tends to be along the
superior portion of the tympanic
membrane so if you now have the vectors
going this way what part of the tympanic
membrane is going to retract?  It's going
to be the pars what?  Flaccida which is up
here because the rest of it is pretty
tense.  So what ends up happening is that
as you as you have this change of
the vectors all of the stuff that
normally flows out of the ear is now
going to get sucked back in and because
the pars flaccida retracts, this is
where this junk is going to end up.  Now
once it gets bigger and bigger you can't
end up with the cholesteatoma but what
do you end up calling this space which
is just lateral to the ossicles
and just medial to this wall right here--
what space is that?  Prussak's space.  And
that's why cholesteatoma is a rise in
Prussak's space, because the vectors reverse
the flaccid part of the tympanic
membrane is superiorly and eventually the
pars flaccida gets sucked in so
that's why this occurs in Prussak's space
and this is the whole concept of the
invagination theory of cholesteatoma.  So
this one actually was a pathologically
proven retraction pocket, the surgeons
went in they took it out and this was a
small retraction pocket located right
here in Prussak's space and there is the
scutum.  Now often times I'll get asked
"Isn't the scutum the first bone that's
eroded?" I mean don't you need scutal
erosion to make the diagnosis and the
answer is no and I think how this came
into the literature was again a result
of conventional tomography because when
you did conventional tomography we just
don't have the anatomic detail that we
do now so the most reliable bone
to become blunted that we could see on
conventional tomography was the scutum
so therefore we would say yeah the scutum
is blunted or eroded therefore that's
cholesteatoma but in actuality at least
in my experience--and you know I can ask
Doug too--the scutum tends to be the last
bone eroded.  I don't know if you--it's
pretty not as common and usually for me
the bone that's most commonly eroded
when I see it is actually the incus; it's
a long process of the incus.  So how do we
make the diagnosis of cholesteatoma?  First
of all you need to see a focal soft
tissue mass and there has to be either
erosion or displacement of the ossicles.
So in this particular case we can see
the manubrium of the malleus we can
see the anterior and posterior crus to
the stapes and we see the soft
tissue mass.  On the right side we can see
the head of the malleus and we can see
absence of the short process--the incas.
So soft tissue mass plus ossicular erosion
or displacement equals cholesteatoma and
if the patient has had a history of
chronic ear infection, that's how we make
the diagnosis of an acquired cholesteatoma.
Another example here on the left hand
side, we see a normal appearance of the
middle ear cavity.  Anybody know the name
of the septum right here, it starts with
a "K"?  Koerner's septum, exactly right and
then on the right hand side we can see
the soft tissue mass and notice how
Koerner's septum is gone and we see
absence of the normal labyrinthian bone
in the mastoid air cells so this is the
indication here that we're dealing with
cholesteatoma again.  We can do MR to look
for cholesteatoma, in general we tend not
to.  If you do do it, cholesteatomas tend
not to enhance with contrast, however
diffusion imaging can be helpful.  So this
is an example of a patient, underwent
multiple ear surgeries--three or four.
The patient still had drainage coming from
the surgical site.
We did a diffusion-weighted imaging and
this is the B1000 and we can see high
signal here involving the cholesteatoma
so this is very bright.  So we do use
cholesteatomas at our place and we are using
echo planar cholesteatoma.  The best
diffusion to use really is line scan but
not all the vendors offer it but if we
do have--you know--a pretty
decent-size mass and we're still not
sure whether or not it's cholesteatoma
we will recommend an MR and specifically
to look for a diffusion because in cases
such as this where you have these
indeterminate lesions here, you're not
sure what that is, if you do do the
diffusion imaging--there it is bright and
here is the ADC value.  See how it's dark
so in selected cases diffusion imaging
can be helpful to distinguish mucosal
thickening from residual or recurrent
cholesteatoma so in selected cases we do
find it helpful.  So in summary what we
tried to do over the last 40 minutes or so
is talk about technique, a little bit
about anatomy, we talked about
otosclerosis, the inner ear malformations,
labyrinthitis and we ended up really
with the most common disease entity that
you'll be performing temporal bone CTs
and that's cholesteatoma.  So thank you
very much for your attention
