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THE ROLE OF HIGH RESOLUTION COMPUTED TOMOGRAPHY (HRCT)
IN EVALUATION OF CHRONIC SUPPURATIVE OTITIS MEDIA WITH
CHOLESTEATOMA; RADIOSURGICAL CORRELATION
By
*Adel MS Mohsen, **Yehia MS El-Kashif.
Departments of *Radiodiagnosis & **ENT - El-Minia Faculty of Medicine
ABSTRACT:
Objective and aim of the work: Chronic otitis media and its complications need
clinical effort for proper diagnosis. Early diagnosis and management can avoid
permanent hearing loss which is common sequelae. The advent of HRCT facilitates
diagnosis of temporal bone, mastoid and inner ear pathologies. The study aimed to
study the value of HRCT in diagnosis of chronic suppurative otitis media with
cholesteatoma, its complications and matching the results surgical findings. Subjects
& methods: The present work included 32 patients within the period from September
2001 to December 2003. They were randomly selected from the Radiology and ENT
Departments in El MINIA University hospital. Their ages ranged from 10 to 65 years
(24.88 + 14.3). All patients presented with clinical picture of suppurative otitis media
such as ear discharge, conductive hearing loss with or without signs of increased
intracranial pressure and facial palsy. Thorough ENT clinical and otoscopic
examinations at the ENT Department were done. Patients presented with vertigo are
examined for the presence of labyrinthine fistula by fistula test. HRCT examinations
were done to all patients using (GE CT/ PROSPEED PLUS Ver.04.00 Scanner, with
512 elements, 256 x 256 matrix. Scanning was done in the direct axial and coronal
planes for optimal demonstration of temporal bone structures. HRCT images were
interpreted to define (1) the nature of inflammatory ear disease; localization and
possible complications (2) To give anatomical and pathological changes needed for
surgical planning and define neoplastic changes (3) To detect the normal variant
important to the surgeon and (4) To evaluate the ear following surgery for the
detection of possible residual, recurrence or post operative complications. Results:
Combined pars flaccida and pars tensa cholesteatomas was the most common type
detected in (37.5%). The attic cholesteatoma was most frequently site seen (31.25%).
The scutum, lateral attic wall erosion & eroded Korner’s septum were the most
common findings seen in (56.3%). Complete erosion of ossicles was seen in (56.3%),
involvement of sinus tympani (Hidden areas) was seen in (34.4%) and sclerotic
mastoid cells in (56.3%).Labyrinthine fistula was seen in (18.8%) of cases and
eroded facial nerve canal in 25% of cases. Diseased other ear was seen in 10 cases
(31.3%) with cholesteatoma seen in (6.3%) of such cases. Temporal bone
complications were the most prevalent complications (50%) with conductive hearing
loss was manifested in 46.9% of cases, meanwhile intracranial complications were
seen only in 4 cases (12.5%). HRCT showed 100% sensitivity in diagnosis of soft
tissue mass, bony erosion, labyrinthine fistula, dehiscent facial nerve canal and
intracranial complications. It showed less accuracy in diagnosis of eroded facial canal
(96.4%), incus erosion (96.4%) and tegmen erosion (94.4%). Conclusion: HRCT is
unique in its ability to display not only the internal bone architecture of middle ear
and mastoid but also presence of soft tissue mass; that a negative scan effectively
excludes possibility of cholesteatoma. It is also valuable in visualization of hidden
areas such as sinus tympani and facial recess beyond otoscopic examination which is
important before decision of surgical strategy. HRCT provides the surgeon about
1
possibility of normal anatomic variation that may be present such as overriding
jugular bulb; alerting him before start surgery, hence avoid intra-operative problems.
Early use of HRCT in cases of chronic suppurative otitis media can save hearing and
improve morbidity.
KEY WORDS:
- History of previous middle ear
operation-if present- was also taken.
- Thorough ENT clinical and otoscopic
examinations at the ENT Department
were done. Patients presented with
vertigo are examined for the presence
of labyrinthine fistula by fistula test
(Nystagmus elicited by the application
of positive or negative pressure to the
external canal in positive cases).
INTRODUCTION:
Otitis media and resultant
hearing loss remain a significant
international health problem in terms
of
prevalence,
economics
and
sequelae. Short and long-term sequelae
of otitis media may be devastating. It
can be avoided if recognized early and
probably treated.1,2
Aim of the work:
The aim of this work is to emphasize
the role, value and impact of HRCT in
diagnosis of chronic suppurative otitis
media with cholesteatoma, its
complications as well as correlation
with operative data.
HRCT examination:
The study was done to all patients
using (GE CT / PROSPEED PLUS
Ver.04.00 Scanner) with 512 elements,
256 x 256 matrix. Zooming and
magnification were done for the
petrous bone on each side and for the
diseased side. The HRCT scan
protocol includes the following factors:
Patient position: supine for the axial
scanning, prone or supine with hyper
extended neck for coronal scanning.
KV…………………120
MA……………….…200
Scan time…………..1.5 Sec
Slice thickness…… 1 mm
Section spacing (Interval) 1mm
Field of view (small) 25cm
Mode……………Bone Algorithm.
Window width (extended) 4000 HU.
Window level …3000
Collimation……1.5mm
Pixels…………0.25mm2
Scanning was done in the direct axial
and coronal planes for optimal
demonstration of temporal bone
structures.
(a) Axial (Horizontal projection):
The patient lies supine with the neck
slightly extended (the cantho-meatal
line is perpendicular to the table top).
PATIENTS AND METHODS:
Patients:
This work included 32 patients within
the period from September 2001 to
December 2003. They were randomly
selected from the Radiology and ENT
departments in El MINIA University
hospital. Fifteen were males and 17
were females, their ages ranged from
10 to 65 years (24.88 + 14.3). All
patients presented with clinical picture
of suppurative otitis media such as ear
discharge, conductive hearing loss with
or without signs of increased
intracranial pressure and facial palsy.
Methods:
Every patient was subjected to the
following studies:
- Full history taking including history
of chronic ear discharge, conductive
hearing loss, symptoms of increased
intracranial tension (Fever, headache,
vomiting) and facial palsy.
2
Scout view was obtained and sections
were performed parallel to the
anthropologic line (plane intersecting
the inferior orbital rim and the superior
margin of the external auditory canal).
The sections were taken at 1mm
increments beginning at the level of
the floor of the hypo-tympanum and
jugular fossa and extending cephaliccally to the level of the arcuate
eminence using line for localization.
(b) Coronal (frontal) projection:
The patient lies in the prone position
with the neck fully extended. A lateral
scout view was performed and sections
performed nearly parallel to the ramus
of the mandible. The gantry of the
scanner was tilted 15٥-20٥ to compensate for an incomplete extension of the
neck. Sections were taken from the
bony Eustachian tube anteriorly,
extended posteriorly to the posterior
wall of the mastoid bone. The coronal
projection was not done in patients
suffering from head trauma and obese
patient with short neck. The coronal
scanning also can be done with the
patient supine with hyperextended
neck.
the normal variant important to the
surgeon (e.g. laterally placed sigmoid
sinus, high riding jugular bulb, thick
Körner’s septum, deep sinus tympani
and prominent cochlear aqueduct. (4)
To evaluate the ear following surgery
for the detection of possible residual,
recurrence
or
post
operative
complications.
Contrast enhancement:
No contrast enhancement was
used, unless there was suspected
vascular mass or suspected intracranial
complications. Intravenous injection of
50 ml Urovideo 75% was given.
Scanning of the brain in these cases
was done pre and post intravenous
contrast media.
Sagittal reformat:
Sagittal reformatting was done
in some cases to define the mastoid
segment, facial nerve canal and stylomastoid foramen.
The hallmarks of cholesteatoma on CT
are based primarily on the presences of
one or more of the following criteria;
(1) A non-dependent soft tissue density
mass (2) Typical location in (attic,
mesotympanum or antrum), associated
with (3) bony erosion of the middle ear
bony walls (i.e. Scutum, lateral attic
wall, anterior tympanic wall, tegmen,
sigmoid sinus plate, Korner’s septum,
posterior and superior metal wall),
erosion of the ossicles, scalloping of
the
mastoid,
erosion
of
the
semicircular canal and facial nerve
canal (tympanic and mastoid segments) may be present.3, 4, 5, 6
A routine study of the
cooperative patient takes 15-20
minutes. The window width and
settings were adjusted to a long gray
scale to allow best visualization of the
temporal bone structures. Images were
photographed to an extended window
level +3500-4000 HU and window
width 250 to 300. When soft tissue
structures were of interest images were
displayed at window widths of
approximately 100-300 HU.
RESULTS:
This study included 32 (15 males
&17 females) patients having chronic
suppurative otitis media with cholesteatoma. The high age incidences were in
the 3rd & 4th decades, while the low
incidence was in 2nd and 6th decades.
Females (53.1%) were more affected
HRCT images were interpreted
in details to define (1) the nature of
inflammatory ear disease; localization
and possible complications (2) To give
anatomic and pathological changes
needed for surgical planning and
define neoplastic changes (3) To detect
3
than males (46.9%). The Age and sex
distribution of patients are presented in
table I.
The clinical presentations of these
patients are presented in table II.
Chronic ear discharge with partial or
complete conductive hearing loss was
the main clinical presentation and
representing (53.1%) followed by
chronic discharge (15.6), chronic discharge with signs of increased intracranial
tension (12.5%) and those with vertigo
and sensorineural hearing loss.(12.5%)
Table (I): Age & sex distribution of chronic suppurative otitis media with
cholesteatoma:
Age in
Sex
Total
years
Male
Female
No.
%
No.
%
No.
%
101
6.67
1
5.9
2
6.25
203
20.0
8
47.1 11
34.4
304
26.7
5
29.4
9
28.1
403
20.0
1
5.9
4
12.5
503
20.0
1
5.9
4
12.5
601
6.67
1
5.9
2
6.25
15
17
32
100
Total
Table (II): Clinical presentations of the studied patients with cholesteatoma:
Clinical presentation
Chronic ear discharge without hearing
loss
Chronic discharge with hearing loss
Chronic discharge with signs of
increased I.C.T
Chronic discharge with facial paresis
Chronic discharge with vertigo and
SNHL
Recurrent cholesteatoma
Total
SNHL: Sensorineural hearing loss
No. of
patients
5
%
15.63
17
4
53.1
12.5
2
4
6.25
12.5
2
6.25
32
100
I.C.T: Intracranial tension.
Location & extent of cholesteatoma
(table IV). The attic cholesteatoma was
most frequently seen (31.25%) then
extensive holo-tympanic acquired
cholesteatoma (28.1%) followed by
attico-antral cholesteatoma in (25 %).
Figs. III→ V
HRCT criteria of the studied group:
The HRCT findings are presented in
tables from table III to table XII.
Type of cholesteatoma: (table III).
Combined pars flaccida and pars tensa
cholesteatomas were the mostly encountered type detected in (37.5%) and
then both pars flaccida & pars tensa
cholesteatomas in (31.25%). See Fig.
(I & II).
Bony erosions of the middle ear bony
walls: (Fig. III, IV) (table V). The
scutum and lateral attic wall erosion
4
was the most common finding in
(56.3%) and eroded Korner’s septum
(56.3%) followed by thinning tegmen
(31.3%) and the least common is the
eroded sigmoid sinus plate (12.5%).
mastoid wall fistula (18.8%) and
mastoid abscess was detected in
(9.4%) cases with infected cholesteatoma. (Fig. VI)
The labyrinth: (table IX)
The lateral semicircular canal fistula
was the most common finding
encountered in (18.8%), eroded whole
structures in (3.1%), and eroded canal
in (9.4%). (Fig. VI, VIII)
Integrity of the ossicular chain: (table
VI). The ossicles was absent or
completely eroded in (56.3%), the
incus was the most commonly affected
(21.9%), followed by malleus erosion
(9.4%). The ossicles were displaced
without erosion only in (12.5%). (Fig.
IV)
Integrity of the facial nerve canal:
(table X). The facial nerve canal was
intact in (68.8%), eroded in (25%) and
dehiscent in (6.3%) of cases. The
whole segments were equally affected
(6.25%). Fig. VI.
Involvement of hidden area (Fig. V),
(table VII). The involvement of the
sinus tympani was detected in (34.4%)
and the facial recess involvement was
encountered in (31.3%).
Condition of the other ear: (table XI).
The other ear was normal in (68.8%)
and diseased in (31.3%), chronic
suppurative otitis was encountered in
(25.0%) and bilateral cholesteatoma in
(6.3%).
Mastoid air cell system: (table VIII).
The sclerotic mastoid was the most
common finding encountered in
(56.3%) of cases. Automastoiectomy
was encountered in (31.3%), lateral
Table (III): Type of cholesteatomas:
Type of cholesteatoma
No. of
patients
10
10
12
32
Pars flaccida cholesteatoma
Pars tensa cholesteatoma
Combined cholesteatoma
Total
%
31.25
31.25
37.5
100
Table (1V): Location & extent of cholesteatoma:
Location & extension
No. of
%
patient
Attic
10
31.25
Attico-antral
8
25.0
Mesotympanum
5
15.6
Extensive (holotympanic) extended to mastoid antrum
9
28.1
Total
32
100
5
(A)
(B)
Figure I: Early cholesteatoma pars flaccida (A) Axial epitympanic and (B) Coronal anterior tympanic
sections through the left petrous bone showed localized tissue density mass (arrow) filling the Prussak’s
space lateral to head and neck of malleus and medial to the blunted scutum. The ossicular chain is
displaced medially. Normally aerated remaining left middle ear cavity. EAC (external auditory canal)
(A)
(B)
Figure II: Early Cholesteatoma pars tensa (A) Axial midtympanic section of the left petrous bone
showed localized tissue density mass seen filling the facial recess and overlying the pyramidal
eminence. Labeled structures include; PE= pyramidal eminence, ST= sinus tympani, BT= basal turn of
the cochlea, V= vestibule, RWN= round window niche, CA= cochlear aqueduct (B) Coronal midtympanic section showing a soft tissue density mass mostly involving the pars tensa of the tympanic
membrane, eroding the incus lenticular process (arrow). Note the opacified meso-tympanum and intact
incus body. Labeled structures include; TM= tympanic membrane, IB=incus body, SSC= superior and
LSC= lateral semicircular canal, IAC = internal auditory canal.
Table (V): Middle ear bony wall erosion:
Bony wall erosion*
No. of
%
patients
Blunted scutum
5
15.6
Eroded scutum & lateral attic wall
18
56.3
Eroded tegmen
5
15.6
Thinning of the tegmen
10
31.3
Eroded sigmoid sinus plate
4
12.5
Eroded superior & posterior meatal wall
5
15.6
Eroded Körner’s septum
18
56.3
*More than one finding may be present in the same patient
6
Table (VI): Integrity of the ossicular chain
Integrity of the ossicles
No. of
patient
18
3
7
4
32
Completely eroded (no ossicles)
Eroded malleus only
Eroded incus only
Displaced intact ossicles
Total
(A)
%
56.3
9.4
21.9
12.5
100.0
(B)
(C)
(D)
Figure III. Attic Cholesteatoma. (A) Axial section IAC level, (B) Axial section lateral semicircular
canal level, (C) Coronal anterior tympanic and (D) Coronal midtympanic level of the right petrous
bone showing a well defined, rounded tissue density mass filling the anterior part of the attic extended
to midtympanic region. The lesion erodes the scutum and malleus head and neck. Note the normal
appearance of the aditus denoting that the lesion is localized within the attic with no antral extension.
Labeled structures in (A) include; Mass= cholesteatoma mass, PE=pyramidal eminence, ST=sinus
tympani and IAC=internal auditory. Labeled structures in (B) include, EPIT C= epitympanic cavity,
ADITUS= aditus ad antrum, MA= Mastoid antrum, LSC= lateral semicircular canal and VA=
vestibular aqueduct. Labeled structures in (C) include; Mass= cholesteatoma mass, TT= tegmen
tympani, GG= geniculate ganglion, COCH= cochlea and CC= carotid canal (vertical segment). Labeled
structures in (D) include; M=mass, EAC=external auditory canal, IAC=internal auditory canal and TT=
tegmen tympani.
7
(A)
(B)
Figure IV. Right attico-antral cholesteatoma pars flaccida (A) Axial section lateral semicircular canal
level and (B) Coronal midtympanic section through the right petrous bone showing a well defined, soft
tissue density mass filling the attic, widen the aditus and extended to the mastoid antrum. The mass
erodes the scutum and supero-posterior meatal wall, Korner’s septum and sigmoid sinus plate. The
tympanic membrane is thickened and retracted. Note that the cholesteatoma mass abutting the anterior
limb of the lateral semicircular canal, which is seen intact in axial section. Labeled structures in (A)
includes; C= cholesteatoma mass and SSP= eroded sigmoid sinus plate. Labeled structures in (B)
include; EC= posterior part of the epitympanic cavity, TM= the thickened retracted tympanic
membrane and LSC= lateral semicircular canal.
Table (VII): The involvement of hidden areas (anterior & posterior tympanum):
Hidden area involved
Posterior tympanum
Sinus tympani
Facial recess
Anterior tympanum
No. of patients
%
11
10
6
34.4
31.3
18.8
Table (VIII): Integrity of mastoid air cell system:
Mastoid state*
No. of
%
patients
Sclerotic
18
56.3
Auto-mastoidectomy
10
31.3
Lateral mastoid wall bony fistula
6
18.8
Mastoid abscess
3
9.4
*More than one finding may be present in the same patient
8
(A)
(B)
Figure V. Extensive cholesteatoma invading the anterior epi-tympanum (hidden area) (A) Coronal
anterior tympanic and (B) Coronal mid-tympanic oval widow level through the left petrous bone. A
large cholesteatoma mass fills the middle ear cavity involving the anterior attic with erosion of the
lateral attic wall, tegmen tympani and the posterosuperior meatal wall. The labeled structures include;
COCH= cochlea, VCC= vertical segment of the carotid canal and the cholesteatomas, SSC and LSC=
superior and lateral semicircular canal, TT= eroded tegmen tympani, IAC= internal auditory canal and
EAC P= external auditory canal polyp.
Table (IX): Integrity of the inner ear:
Inner ear state
No. of
patients
Intact inner ear structures
23
Lateral semicircular canal (LSC) fistula 6
Eroded inner ear structures (cochlea, 1
vestibule & semicircular canals)
Eroded Internal Auditory Canal (IAC)
3
%
71.9
18.8
3.1
9.4
Table (X): Integrity of the facial nerve canal:
Facial Nerve Canal state (FNC)
Intact FNC
Dehiscent FNC
Eroded FNC:
Proximal tympanic segment
Distal tympanic segment
All tympanic (horizontal) segment
Vertical segment
Total
9
No. of patients
22
2
8
2
2
2
2
32
%
68.8
6.3
25.0
6.25
6.25
6.25
6.25
100.0
Table (XI): The condition of the other ear:
Other ear
No. of
patients
22
10
8
2
32
Normal other ear
Diseased
Chronic suppurative otitis media
Bilateral Cholesteatoma
Total
(A)
%
68.8
31.3
25.0
6.3
100
(B)
Figure VI. Extensive cholesteatoma. (A) Axial lateral semicircular canal section (B)
Coronal jugular foramen and posterior middle ear sections through the right petrous
bone. A large cholesteatoma mass fills the whole middle ear cavity eroding the lateral
semicircular canal with subsequent labyrinthine fistula and the mastoid air cells with
subsequent automastoidectomy. Labeled structures include; C= cholesteatoma mass,
LSC F= lateral semicircular canal fistula, V= vestibule, IAC= internal auditory canal,
PSC=posterior semicircular canal, MA= mastoid antrum, DFNC= descending facial
nerve canal and the JF= jugular foramen.
labyrinthine fistula (18.8%), post
auricular abscess (18.8%), sigmoid
Complications
of
chronic
sinus plate erosion (15.6%) and the
suppurative otitis media with
Cholesteatoma: (see table XII).
least
complication
was
the
Temporal bone complications were
sensorineural hearing loss (6.52%).
Regarding intracranial complications,
prevalent more than those of
the cerebellar, cerebral extradural
intracranial
complications.
The
abscesses and otitic hydrocephalus
ossicular destruction was the mostly
were equally encountered in (3.1%) of
encountered complication (50%),
cases.
followed by conductive hearing loss
(46.9%), auto-mastoidectomy (31.3%),
Table XII: Temporal bone and intracranial complications in 32 patients with
Cholesteatoma:
10
Complications*
No.
patients
of %
Temporal bone complications
Complete ossicular destruction 16
50.00
Automastoidectomy
10
31.3
Mastoid wall fistula
6
18.8
Conductive hearing loss
15
46.9
Total hearing loss
2
6.52
LSC fistula
6
18.75
Mastoid abscess
1
3.1
Post auricular & zygomatic 6
18.8
abscess
5
15.6
Eroded sigmoid sinus plate
Intracranial complications
Cerebellar abscess
1
3.1
Cerebral abscess
1
3.1
Extradural abscess
1
3.1
Otitic hydrocephalus
1
3.1
*More than one finding may be present in the same patient
(A)
(B)
Figure VII. Infected cholesteatoma with abscess formation (A) Axial lateral and
superior semicircular canal sections through the right petrous bone showing diffuse
soft tissue density mass filling the mastoid antrum (MA) and eroding the sigmoid
sinus plate (SSP). (B) Axial enhanced CT section of the brain showing extradural
abscess (EDA) and zygomatic abscess (ZA).
(A)
(B)
11
(C)
Figure VIII. Extensive cholesteatoma eroding the petrous pyramid and osseous
labyrinth (A) Axial inferior tympanic section and (B) Coronal anterior tympanic
section of the right petrous bone showed middle ear cavity tissue density mass
eroding the lateral attic wall, scutum and ossicles and bony labyrinth (long white &
black arrows), the tegmen is thinned (short black arrow).The lesion erodes the
labyrinthine and tympanic segments of the facial nerve canal. The attic, aditus and
mastoid antrum are opacified with tissue density and the mastoid air cells are
sclerotic.(C) Axial section through the posterior fossa in the same patient with
contrast showed right cerebellar abscess.
were demonstrated with CT scan and
the preoperative CT scans agreed with
surgical findings of incus erosion in 25
patients (96.4%). Of 18 patients with
Correlation between HRCT findings
and operative features: (table XIII)
HRCT scans showed the presence of a
non dependent tissue mass in 26 out of
32 patients with cholesteatoma
(92.8%), the location of the pathology
on the scan was typical for
cholesteatoma in 27 patients (96.4%)
and in 28 patients (100%) there was
radiological evidence of erosion or
destruction of the bony walls of the
middle ear, mastoid antrum or ossicles.
All patients had at least one of the
above radiological features, and 26
(92.8%) patients showed all 3 features.
Based on these features 27 ears with
cholesteatoma (96.4%) were accurately
diagnosed by the HRCT scans.
This revealed that the accuracy and
sensitivity was excellent regarding
malleus erosion, lateral semicircular
canal fistula, sigmoid sinus plate
erosion and intracranial complications,
very good correlation regarding incus
erosion and the tegmen tympani
erosion and good for the facial nerve
canal.
State of the ossicles:
Out of the 26 patients with incus
erosion found at surgery, 25 patients
eroded malleus, 18 were seen by the
scan with accuracy (100%). The stapes
is not visualized consistently by CT
scan and not analyzed in this study.
Semicircular canal fistula:
There were 6 patients with surgically
confirmed
labyrinthine
fistula.
Preoperative CT scan diagnosed all the
6 patients of lateral semicircular canal
fistulas accurately. In the remaining
cases, there were no false positive
radiographic interpretations, and thus
complete agreement was obtained.
Erosion of the tegmen tympani:
The tegmen is visualized in coronal
sections, appears as a thin bony plate
overlying the epitympanum and
antrum. There was agreement in (94.4
%) between the preoperative CT scan
and operative features. One case was
diagnosed as eroded tegmen and the
operative features showed only
dehiscence of the tegmen with no dural
exposure.
Integrity of the facial nerve canal:
12
In this study, CT scans found
agreement about facial nerve canal
integrity in 22 patients (68.8%) and
surgery. Out of 8 patients with surgical
confirmation of eroded facial nerve
canal, CT could detect 7 patients in the
present study. CT is agreed with
operative features regarding 2 patients
with facial canal dehiscence.
Integrity of the sigmoid sinus plate:
Four patients of sigmoid sinus plate
erosion were diagnosed accurately by
preoperative CT scans.
Intracranial complications:
Five
patients
with
intracranial
complications including cerebellar
cerebral, extradural abscesses and
otitic hydrocephalus were diagnosed
accurately be preoperative CT scans.
Table XIII. Correlation between CT findings and operative features:
Features
Tissue mass
Typical
location
Bony erosions
Incus erosion
Malleus
erosion
LSC fistula
Tegmen
erosion
Facial canal
Intact
Eroded
Dehiscent
Eroded SSP
Eroded KS
Intracranial
complications
LSC: lateral
KS:
Finding in
CT
26
27
Operative
Features
26
27
False
Negative
0
0
False
Positive
0
0
Accuracy Sensitivity
100
100
100
100
32
25
18
32
26
18
0
1
0
0
0
0
100
96.4
100
100
96.1
100
6
5
6
4
0
0
0
1
100
94.4
100
100
22
8
2
5
18
4
22
9
2
5
18
4
0
1
0
0
0
0
0
0
0
0
0
0
100
96.4
100
100
100
100
100
83.3
100
100
100
100
semicircular canal
Korner’s
The incidence of the petrous bone
13
SSP: Sigmoid sinus plate.
septum
anatomical
normal
variations:
(Table XIV)
Dehiscent jugular fossa (Fig. IX) was
the mostly encountered normal variant
(9 cases) followed by laterally placed
sigmoid sinus (4 cases), high riding
jugular bulb (3 cases), (Fig.X), deep
sinus tympani (2 cases), high riding
non dehiscent jugular bulb with
diverticulum (one case).
Table XIV: The incidence of petrous
bone normal variants in studied
patients:
(A)
Normal variant
Patients'
No.
jugular 9
%
Dehiscent
fossa
High riding jugular
bulb
High riding jugular
bulb
with
diverticulum
Anteriorly
&
laterally
placed
sigmoid sinus
Deep
sinus
tympani
Total
2.9
3
0.96
1
0.32
4
1.28
2
0.64
19
6.08
(B)
Figure IX. Dehiscent jugular fossa with post-inflammatory ossicular fixation right (A)
Axial inferior tympanic section and (B) Coronal section oval window level of the
right petrous bone showing dehiscent jugular fossa, normally aerated middle ear
cavity with sclerotic mastoid. Note the fibrous tissue extending from the thickened
tympanic membrane to the oval window making a post inflammatory ossicular
fixation. Labeled structures include DJF= dehiscent jugular fossa and FTF= Fibrous
tissue fixation.
(A)
(B)
(B)
14
Figure X. High riding jugular bulb with diverticulum (A) Axial midtympanic section
and (B) Coronal jugular foramen level section of the left petrous bone showing high
riding jugular bulb with superior diverticulum. Labeled structures include; HRJ= high
riding jugular bulb and JD= jugular bulb diverticulum.
DISCUSSION
Chronic suppurative otitis media is
divided into 2 main clinical types. The
first variety tends to follow a benign
clinical course where there is a
persistent perforation of the tympanic
membrane; chronic suppurative otitis
media without cholesteatoma or tubotympanic type. The other type is more
aggressive and follows a dangerous
course of destruction of the middle ear,
mastoid antrum and termed chronic
suppurative
otitis
media
with
cholesteatoma or tympano-mastoid
variety.(7)
High-resolution CT is ideal for the
evaluation of middle-ear pathology.
Contrast-enhanced CT is useful if an
intracranial complication is suspected
and if brain hernia (encephalocele) is
present in revision surgery. HRCT
offers high-resolution images that
allow good visualization of the
anatomy of the bones, ossicles, and
inner ear. (8 & 9)
Acquired cholesteatoma divided into
primary acquired (no history of otitis
media, usually pars flaccida) and
secondary acquired (positive history
for previous infection). Primary
acquired cholesteatomas arise as a
result
of
tympanic
membrane
retraction.
Secondary
acquired
cholesteatomas occur as a direct
consequence of injury to the tympanic
membrane. This injury can be a
perforation that has arisen as a result of
acute otitis media or trauma, or it may
be due to surgical manipulation of the
drum. (4, 5, 10)
In HRCT the axial projection allows
visualization of most of temporal bone
anatomy, delineating the sinus
tympani,
facial
recess,
lateral
semicircular canal, Körner’s septum,
incudo-malleolar and incudo-stapedial
articulations, horizontal segment of the
facial nerve canal, internal auditory
canal, vestibular aqueduct, oval and
round windows and temporal ear
pathology. Coronal scans is valuable in
evaluating scutum, Prussak’s space,
roof of the tympanic cavity (tegmen),
geniculate ganglion, oval window,
stapes, ossicles heads (malleus and
stapes), oval window, jugular fossa,
internal auditory canal, vestibule and
the vertical segment of the facial nerve
canal. Axial images should include top
of the petrous apex to the inferior tip of
mastoid, and coronal images should be
obtained from the anterior margin of
petrous apex to the posterior margin of
the mastoid. (11)
In adults, aural polyps often represent
an irritative response to chronic otitis
media but may herald the presence of
cholesteatoma.(13) Gliklich et al., 1993
(14)
and Chakeres; et al., 1985(15)
concluded that patients with primary
aural polyps unresponsive to medical
therapy
should
undergo
the
performance of audiogram and CT
15
scan of the temporal bone prior to
surgical intervention. The presence of
temporal bone erosion on CT heightens
the concern of severe underlying
abnormality
(malignancy
or
cholesteatoma).
In the present study; the high incidence
of cholesteatoma was in the 3rd decade
of age with a history of recurrent
chronic otitis media, tympanic
membrane perforation and Eustachian
tube dysfunction, while the low
incidence was in 6th decade. David
White 1997(16) stated that acquired
cholesteatoma are more common in
patients < 30 years. In a study of
Kemppainen et al., 1999(10) the mean
annual incidence was 9.2 per 100,000
inhabitants and the incidence was
higher among males < age of 50 years.
In the present study, tympanostomy
was carried out in 10.2% and
adenoidectomy or adeno-tonsillectomy
in 15.9% of cholesteatoma ears prior to
surgery.
HRCT features of cholesteatoma of
the studied patients:
In the present study, and according to
the criteria of (3, 4, 5, 6), we found that
secondary acquired cholesteatoma
were most often localized to the attic
and antrum, some extended to the
meso-tympanum and some are holotympanic. Attic cholesteatoma was
detected in 10 patients (31.25%),
attico-antral cholesteatoma in 8
patients
(25%),
meso-tympanic
cholesteatoma detected in 5 patients
(15.6%) and extensive holo-tympanic
cholesteatoma in 9 patients (28.1%).
Regarding the type of cholesteatoma,
10 patients out of 32 patients showed
CT features of pars flaccida
cholesteatoma (31.25%), 10 patients
out of 32 were of pars tensa
cholesteatoma (3.25%) and combined
types cholesteatomas in 12 patients
(37.5%). If Prussak’s space is clear and
there is no pars flaccida retraction, we
presumed cholesteatoma to arise from
the pars tensa.
Liu and Bergeron 1989(6) stated that
CT is a unique in its ability to display
not only the internal bony architecture
of the temporal bone but also to
evaluate the soft tissue components
associated with a pathologic process.
Therefore;
one
of
its
major
contributions to the otologist dealing
with cholesteatoma is the preoperative
localization of the cholesteatomatous
sac, a detail not only determine the
type of surgical approach but may also
alert the surgeon to possible intraoperative as well postoperative
complications. HRCT can early detect
cholesteatoma associated with subtle
bony
erosion
or
ossicular
displacement. This early detection by
HRCT with the use of simple non
invasive surgical technique (as delivery
or atticotomy) will preserve hearing.
In the current study, small attic and
meso-tympanic cholesteatoma were
demonstrated in 10 patients out of 32
patients. Early Prussak’s space
cholesteatoma was detected in 2
patients as a localized small soft tissue
density mass slightly eroding the
scutum in one patient and displaces the
ossicles medially in the other patient.
Early meso-tympanic cholesteatoma
extending from a postero-superior
retraction related to the facial recess
and sinus tympani detected in 3
patients associated with slightly eroded
incus long and lenticular process. The
remaining 2 patients showed localized
attic cholesteatoma associated with
erosion of the scutum, malleus head
and neck with slight extension towards
the aditus.
Phelps and Lloyd 1990(17) stated that,
demonstration of small cholesteatoma
in the middle ear cavity by CT depends
on two factors: the first is the bone
erosion of lateral attic wall and scutum
and/or displacement of the ossicles and
the second factor is the morphology of
16
a soft tissue mass, which is typically
seen in the attic and extends down to
the isthmus of the middle ear. The
ossicular chain is normally equidistant
from the medial and lateral walls of the
epi-tympanum.
The
ossicular
displacement in either direction often
is an early sign of cholesteatoma. Pars
flaccida
cholesteatomas
usually
displace the ossicular chain medially,
and pars tensa cholesteatoma displace
it laterally.(18)
Mafee et al 1988(18) and David et al
1989(19)
described
the
criteria
indicating cholesteatoma in the attic as
follows: destruction of the lateral spur
of bone formed by the junction of the
lateral attic wall and roof of the
external auditory canal (scutum).
Blunting of the scutum’s (normally
sharp tip) is the earliest sign of attic
cholesteatoma. Erosion of the anterior
tympanic spine (which is best seen in
sagittal scans), is another sign
indicating cholesteatoma in the attic.
Bone destruction of the lateral attic
wall causing widening of the aditus
with loss of the “figure-of-eight”
pattern (formed by narrow isthmus of
the aditus between the radiolucencies
of the epitympanum and antrum)
usually signifies that cholesteatoma has
extends into the antrum. Dehiscence of
the tegmen and erosion of the medial
attic wall are less common than lateral
wall erosion and may lead to
involvement of the facial nerve canal
with paralysis and invasion of the
lateral semicircular canal with vertigo
or sudden sensorineural hearing loss.
Cholesteatoma in the mastoid antrum
is characterized by a smooth cavity that
is usually larger than normal owing to
bone erosion. When the air cells appear
cloudy but maintain their irregular
trabecullar pattern or whenever there is
obliteration of the mastoid antrum and
peripheral air cells by reactive new
bone formation, chronic mastoiditis
without cholesteatoma is indicated.
Another sign of cholesteatoma in the
antrum is erosion or absence of the
bony partition known as Körner’s
septum. So, it is mandatory to compare
both ears, because of the normal
anatomic variations among individuals.
Destruction and scalloping of the
mastoid
air
cells
(automastoidectomy), dehiscence or erosion
of the sigmoid sinus plate with or
without venous sinus thrombosis
represents the complications of antral
cholesteatoma.(18)
Hidden cholesteatoma:
The anatomy of the posterior
tympanum is quite complex. The
pyramidal eminence from which the
stapedial tendon arises is the most
prominent structures on the posterior
tympanic wall. It is bordered medially
by the sinus tympani and laterally by
the facial recess. They are important in
that, cholesteatoma material may lie
within and be hidden from view during
surgery.
Detection
of
hidden
cholesteatoma within the posterior or
the anterior tympanum by HRCT
makes it the method of choice.(20)
In the present study; CT scan
demonstrate the involvement of
posterior tympanic recesses (sinus
tympani and facial recess) by
cholesteatoma mass in 21 out of 32
patients
(65.6%),
the
anterior
tympanum involved in 6 patients
(18.8%). This is consistent with results
of Hasso et al., 1988 (21&22) and Mafee
1988(18) who mentioned that CT could
demonstrate cholesteatomas in hidden
areas such as the posterior tympanic
recesses, which could not be detected
by
the
otologic
examination.
Evaluation of these recesses of the
tympanic cavity is essential prior to
surgery since the surgical approach
may be altered by the presence of
inflammatory disease medial to
ossicular chain. The anterior epitympanum corresponds to the ossicular
space and is very difficult to view with
17
patients. Sadé et al 1982 (27) concluded
that ossicular chain erosion occurs in
30% of patient with cholesteatoma.
Erosion of the lenticular process and
stapes superstructure may produce a
conductive hearing loss. Combined
sensorineural and conductive hearing
loss detected in two patients having
extensive cholesteatoma eroding the
middle ear structures and invading the
osseous labyrinth. The presence of
sensorineural hearing loss may indicate
involvement of the labyrinth.(27)
Labyrinthine fistula:
It is encountered in 6 of patients with
cholesteatoma. One of these patients
presented
with
vertigo
and
sensorineural hearing loss as well as
positive fistula test. The other 5
patients were discovered accidentally
by HRCT scan with no symptoms of
labyrinthine fistula. Silver et al., 1987
(28)
stated that patients with vertigo and
chronic middle ear disease may have a
cholesteatoma with a "fistula" between
the middle and inner ear. Although the
fistula usually involves the lateral
semicircular canal, the cholesteatoma
may invade the oval window. Palva
1990(29) concluded that the labyrinthine
fistula may occur in 10% of patients
with cholesteatoma. A fistula should be
suspected in patients with longstanding
disease and have sensorineural hearing
loss and/or vertigo induced by noise or
pressure changes in the middle ear.
HRCT scan of the temporal bone
should be obtained to confirm the
diagnosis.
Facial nerve paresis was detected in
two patients with cholesteatoma
eroding the horizontal portion of the
facial nerve canal. The paresis
developed slowly from chronic
expansion of the cholesteatoma. HRCT
of the temporal bone helps to localize
the site of involvement.
Intra-cranial complications:
In the present study intracranial
complications were encountered in 4
operating microscope even after
removal of the head of malleus. These
described hidden areas give a bad
reputation
of
recurrence
of
cholesteatoma.
Extensive holo-tympanic
cholesteatoma:
In this study 9 patients out of 32
(28.1%) presented with extensive
cholesteatoma that filling the whole
tympanic cavity and extended to
mastoid antrum. The diagnosis
depends on that, the cholesteatoma had
a propensity for bony erosions of the
middle ear bony boundaries and
mastoid and did not gravitate (non
dependent) in axial and coronal
sections. These features are consistent
with, Voorhees et al.,1983 (23) and
Jackler et al., 1984 (24) who depended
mainly on the bony erosion not the CT
numbers in the diagnosis of holotympanic cholesteatoma.
Sara, 1991(25) and Mafee et al., 1988(18)
reported that whereas CT scan
produces
excellent
soft
tissue
resolution, the differentiation of
pathological processes on the bases of
CT numbers proved to be unsuccessful,
because
acquired
cholesteatoma,
granulation tissue and middle ear
effusion, all share similar CT numbers.
Therefore; secondary findings and
clinical information must be relied
upon to make a definitive diagnosis.
Complications of cholesteatoma:
Virtually all complications of the
cholesteatoma are related to osseous
destruction. The ability to destroy bone
may lead to serious intracranial
complications.
Although
these
complications may produce obvious
signs and symptoms, they may be
subtle and unrecognized without CT
scan.(5, 26)
Intra-temporal complications:
In the present study; conductive
hearing loss is a common complication
of cholesteatoma as ossicular chain
erosion occurred in as many as 50 % of
18
patients
(14.28%).The
cerebellar
abscess was a sequel of invasive
cholesteatoma eroding the sigmoid
sinus plate. The extradural abscesses
were detected in one patient having
infected
cholesteatoma
eroding
sigmoid sinus plate and the tegmen
mastoidium. Otitic hydrocephalus was
detected in one patient complaining of
intermittent headache. CT scan
excludes the presence of cerebral
abscess and showed attenuated
ventricular system.
EL-Essawy et al 1992 (30) in a series of
(32 cases) concluded that, the temporal
bone complications including bone
erosion and cavity formation were seen
in all patients with cholesteatoma
(100%), sclerosis of the mastoid and
ossicular destruction in 30 patients
(93.8%).The intracranial complications
represented in (21.7%) in the 32 ears
due to negligence of treatment and
delayed operative interference in
addition to un-awareness of the value
of CT in detection of these
complications.
Value of preoperative HRCT in
patients with cholesteatoma:
The
absolute
indications
for
preoperative HRCT in chronic otitis
media were described by Falcioni et
al.,2002 (31) which include: doubtful
diagnosis, suspected malformations,
difficult
microscopy
evaluation,
suspected petrous apex cholesteatoma,
suspected intracranial complications,
and review of cases that did
mastoidectomy before. The scan aids
in alerting surgeon to the presence of
anatomical variations (such as a high
riding jugular bulb, prominent laterally
placed sigmoid sinus, aberrant carotid
artery), and potential surgical hazards
that may arise from destructive nature
of the disease (such as labyrinthine
dehiscence).(32)
Correlation between HRCT findings
and operative data:
HRCT findings of labyrinthine fistula
were compared with operative features
and fistula test. CT findings were
coincident with operative data for all
studied parameters and the least one is
the integrity of the facial nerve canal.
Thirty one patients out of 32 with
cholesteatoma accurately diagnosed
with HRCT scan (96.4%), only one
patient with diffuse tissue density in
the
attic
and
meso-tympanum
associated with eroded incus long
process was diagnosed as acquired
mesotympanic cholesteatoma, but the
surgery showed diffuse granulation
tissue with eroded incus long process.
This coincides with Mafee et al 1988
(18)
who reported that (96%) of cases
were diagnosed correctly with the
preoperative CT scan.
Chee &Tan, 2001(32) concluded that
(94.4%) of cases had at least 2 of the 3
criteria
of
CT
features
of
cholesteatoma. Both Jackler et al.,
1984 (24) and O’Donoghue et al., 1987
(33)
, found cholesteatoma presents in
80% of the cases explored. O’Reilly et
al 1991(34) detected 23 out of 29 cases
(79%) of cholesteatoma.
HRCT
images may influence the decision and
timing of surgical exploration. CT scan
evidence of cholesteatoma with
significant bony destruction or other
complications could prompt the
surgeon to operate earlier, particularly
if polyps or a tortuous bony canal
obscures visualization of the tympanic
membrane and hinders clinical
diagnosis.(32)
Ossicular chain erosion:
Bone resorption of the ossicles
depends on the origin and mode of
spread of cholesteatoma.(4,5,32) In the
present
study,
radio-surgical
correlation for the middle ear ossicular
erosion was (96.4%) for the incus
erosion and (100%) for the malleus
erosion. These features are matched
with a study made by Chee &Tan,
2001(32) who found that, out of 31
19
incus, found at surgery to be eroded;
30 were demonstrated by CT scan with
accuracy (96.8%) and out of the 15
malleus, 14 were seen by the scan with
accuracy (96.8%). In a study done by
Mafee et al., 1988(18) the radio-surgical
correlation was (94%) for the incus and
(89%) for the malleus erosions.
Hassman et al., 2003 (35) in a series of
60 ears operated between 1988-2001
reported that there is good correlation
between CT finding and operative
features in cholesteatoma for most
middle ear structures except for the
integrity of incus long process.
On the other hand, O’Reilly et al.,
1991 (34) were able to correctly predict
an intact ossicular chain in only (50%)
of cases. O’Donoghue et al., 1987 (33)
reported that erosion of the long
process of the incus detected in (67%)
of the scanned cases. Phelps and
Wright 1990 (36) stated that the error in
all cases to demonstrate the ossicular
chain reliability was due to the
combination of partial volume
averaging and tissue silhouetting.
While prior knowledge of the state of
the ossicles is not critical as the
operative risk is concerned, it has
bearing on the likelihood of hearing
preservation that can be achieved after
surgery. For example, the hearing
outcomes in patients with an intact
stapes tend to be better than those
where the stapes super-structure is
absent. Pre-surgical knowledge of the
status of the ossicular chain would
allow the surgeon to better advise the
patient on the degree of hearing
attainable after surgery.(37)
Labyrinthine fistula:
In the present study only 6 patients
with lateral semicircular canal fistulas,
were diagnosed. The HRCT findings
were correlated with fistula tests as
well as operative data. A labyrinthine
fistula is caused by resorption of the
bone of the otic capsule by the action
of
enzymes
associated
with
cholesteatoma or chronic active
suppurative osteitis. The most common
site for a fistula is the lateral
semicircular canal. However, any of
the canals may be involved and a
cochlear fistula may occur in the
middle ear or epi-tympanum. These
results were in agreement with those of
Mafee et al (1988) and Chee &Tan
(2001) (32).
Busaba,19
99 (38) mentioned that the labyrinthine
fistula was detected radiologically in
42% of patients. He concluded that in
chronic otitis media, labyrinthine
fistulas occurred almost exclusively in
the presence of cholesteatoma and the
postoperative
hearing
outcome
correlated with the size of the fistula
and the presence of granulation tissue
invading the labyrinth.
Menif et al., 2000 (39) stated that;
HRCT scan assessment of osseous
labyrinthine fistula coincided with the
surgical findings (14 cases of
labyrinthine fistula suspected by CT
was surgically confirmed). Phelps and
Wright 1990 (36) advocated scanning in
both axial and coronal planes when
vestibular symptoms were present.
Mafee et al., (18) stated that, axial
sections may give a false impression of
lateral semicircular fistula and another
plane (coronal or sagittal) should be
obtained. Jackler et al.,1984 (24)
reported that the most common canal
affected by fistula is the lateral
semicircular canal and reliance on
coronal sections alone may lead to a
(50%) false positives rate of
dehiscence due to the artifact of partial
volume averaging. Even with the
addition of axial scans, minute fistula
may still be missed and the careful
dissection of the cholesteatoma matrix
over the dome of the lateral
semicircular canal revealed a tiny bony
canal fistula.
The axial scans are more satisfactory
because they depicted the lateral
20
semicircular canal in its entirety and
were less like to produce false
positives, but useful information could
be gained from the coronal scans. We
recommended both planes for accurate
diagnosis.
Walshe et al., 2002 (40) stated that, there
may be a medico-legal role for routine
CT before mastoid surgery. For
example, erosion of the lateral
semicircular canal by cholesteatoma in
the absence of vertigo is presumably
due to cholesteatoma sealing the
defect.
When
removed
at
mastoidectomy, such a patient may
well become vertiginous. With
evidence of erosion in the preoperative
HRCT, any accusation of iatrogenic
damage could be refuted.
Tegmen erosion:
Tegmen tympani represent the roof of
the middle ear cavity. Erosion of the
tegmen is well seen on coronal
imaging. In this study tegmen erosion
was detected in 5 patients with
accuracy 94.4%. One case was
diagnosed as eroded tegmen and the
operative features showed only
dehiscence of the tegmen with no dural
exposure. Mafee et al., 1988(18) had
similar results as CT findings matched
with operative data regarding tegmen
erosion were seen in 94% of cases.
Also the accuracy in a study made by
Chee & Tan (32) was 94.5%.
Facial canal integrity:
Out of 9 patients with surgically
confirmed facial canal erosion, 8
patients detected by CT with accuracy
(96.4%) and sensitivity (83.3%). In a
study made by Mafee et al 1988,(18)
they diagnosed normal facial canal in
41 patients (85%). They also reported
that to fully visualize the vertical
segment of the canal, one must utilize
the sagittal plane, which is not
available in all CT scanners. When the
middle ear is normal, the thin lateral
bony wall of the fallopian canal is easy
to visualize on CT scans against its
black radiolucent background. But
when pathologic soft tissue abuts the
tympanic portion of the canal, it may
be difficult to determine whether
cholesteatoma has eroded the canal or
merely lies adjacent to congenital
defect.(18)
The problem with partial volume
averaging artifact is evident as the
fallopian canal can be so thin even in
non-pathological ears to appear
dehiscence in CT scan. Also
visualizing the tympanic portion of the
facial canal is difficult when there is an
adjacent pathologic soft tissue mass in
the meso-tympanum.(24,18)
Recurrent chronic suppurative otitis
media in postoperative ear:
The
postoperative
radiographic
evaluation requires information about;
the pathology for which the surgery
performed, the type of surgery, the
clinical and otoscopic findings that
make further CT studies necessary.
(3,41)
Ideally, whenever the surgeon
feels that at the end of surgery there is
residual disease, he should secure a
postoperative study, which can serves
as a baseline for subsequent
evaluations.(42)
The
diagnosis
of
recurrent
cholesteatoma depends on the presence
of new bone erosion not detected in the
preoperative evaluation, the presence
of tissue density mass with well
defined borders and an air space
between the mass and walls of the
tympanic cavity noted, expansion of
the mastoidectomy cavity and thinning
of its walls. Residual cholesteatoma is
considered if the cholesteatoma matrix
or sac is retained over exposed dura,
lateral sinus, facial nerve or
labyrinthine fistula. .(42)
The present study showed that 2
patients had localized middle ear tissue
density mass with well-defined margin.
One of them was diagnosed as
recurrent cholesteatoma and the other
as residual cholesteatoma sac left
21
around the oval window.
The
diagnosis of recurrent cholesteatoma
depends on the bone erosions in the
form of eroded tegmen and anterior
epi-tympanic wall, which were not
detected in preoperative CT and
operative data. This finding is
coincides with Gristwood &Venables
1990 (43) who stated that the incidence
of recurrent or residual cholesteatoma
in
patients
have
undergone
mastoidectomy ranges from 5% to
51%. In another study made by Lino et
al.,1998(44) the rate of residual /
recurrent cholesteatoma after an
average of 10 years from the initial
surgery (canal wall down) varied from
6% to 38%. The risk factors
documented are poor cavity ventilation
and associated otitis media with
effusion.(44)
Tierney et al., 1999(45) revealed that the
sensitivity of CT scan in diagnosing
residual or recurrent cholesteatoma
was 42.9% with a specificity of 48.3%
and a predictive value of 28.6%. These
results explained by the fact that it is
radiologically difficult to differentiate
between recurrence, scar tissue or fluid
with HRCT scan.
Mukherji et al., 1994(46) stated that
because of its superior visualization of
bone detail, compared with that of
MRI, CT commonly used in patient
who have had otomastoid surgry or
other form of temporal bone surgery.
Swartz JD et al.,(47) recommend HRCT
scan in cases where there is a high risk
of recurrent disease at approximately
three-months post-surgery following
resolution of acute postoperative
changes to establish a baseline for
further examination.
HRCT of the post mastoidectomy ear
provides information about the status
of the bony margin of the mastoid
bowel and the amount of soft tissue
density debris in the middle ear cavity
proper. The surgeon must be cautioned
in presence of tegmen defects to the
possibility of an accompanying
meningocele or meningo-encphalocele.
It is also worth noting that the surgeon
may be unable to elicit from the patient
or past medical records the exact type
of mastoid surgery performed. HRCT
can provide information in this respect,
which is often not immediately
apparent upon inspection of the cavity.
Primary petrous apex cholesteatoma
was suggested by the site and
expanding nature as well as the
extension of the lesion through the
petrous pyramid and these findings
aided by clinical presentation (facial
palsy).
HRCT scan could not differentiate
between
primary petrous
apex
cholesteatoma and the possible petrous
apex
granuloma, so
MRI is
recommended to solve the problem.
These findings are matched with
results of Valvassori, 1993 (48) who
stated that the first sign of primary
petrous apex cholesteatoma is often
facial paralysis of slow onset followed
by sensorineural hearing loss caused
by erosion of the labyrinth while the
middle ear cavity may be normal.
HRCT showed expansile lesion in the
apex.
Normal anatomical variations:
The pre-operative knowledge of
normal anatomic variants is very
valuable to the otologic surgeon. The
important normal anatomical variations
include; anteriorly and laterally placed
sigmoid sinus which may lies within
the mastoid antrum, which would
obviously
make
surgery
more
complicated particularly if a post
auricular approach is planned. A
dehiscent jugular fossa may have
similar implications, the jugular fossa
may be separated by only a thin bony
plate from the hypo-tympanum, the
jugular vein may extends into the
hypo-tympanum and in other cases the
jugular bulb may fill the hypotympanum and meso-tympanum. The
22
importance of sinus tympani is
exaggerated if it is unusually deep. In
cases with thick Korner’s septum the
surgeon may believe that the entire
antrum has been explored when indeed
the more medial aspect has not.(4,20)
The large cochlear aqueduct is
significant if surgery is planned around
the oval window. In these patients
there is a higher incidence of
cerebrospinal fluid leak (satpes gusher)
due to low-lying middle cranial fossa
dura. It occurs due to absence of
tegmental
pneumatization.
The
dehiscence of horizontal portion of the
facial nerve canal can be diagnosed by
HRCT. This has obvious implications
when surgery is planned in the oval
window region.(20)
The incidence of normal anatomical
variations encountered in this study
seen in 19 patients. Dehiscent jugular
fossa was the mostly encountered
normal variant (9 patients) followed by
laterally placed sigmoid sinus (4
patients), high riding jugular bulb (3
patients), and deep sinus tympani (2
patients).
A study made by Tomura et al., 1995
(49)
in a series of 325 patients, six
groups of variants were evaluated on
HRCT scan. These include; an
incomplete bony covering of a high
position jugular bulb (2.4%),severe
asymmetry of the jugular foramen
(4%),an anteriorly located sigmoid
sinus (1.6%),deep sinus tympani
(5.9%), large internal auditory canal
(2.3%) and large cochlear aqueduct
(3%).
Virapongse et al., 1986 (50) stated that
CT is valuable in the demonstration of
Korner’s septum. Because thick
septum on CT can be mistaken for the
medial mastoid wall during surgery,
therefore is helpful in the preoperative
surgical planning of the temporal bone
and skull base. A high riding jugular
bulb projecting into the middle ear is a
vascular anomaly, which may present
with conductive deafness and tinnitus.
In this condition a blue or pink mass is
seen arising out of the hypotympanum.(51) The aberrant internal
carotid artery passing through the
middle ear giving a similar appearance.
In undetected cases tympanotomy and
biopsy have been associated with
severe hemorrhage or even death.(52)
Conclusion:
HRCT is unique in its ability to display
not only the internal bone architecture
of middle ear and mastoid but also
presence of soft tissue mass; that a
negative scan effectively excludes
possibility of cholesteatoma. It is also
valuable in visualization of hidden
areas such as sinus tympani and facial
recess beyond otoscopic examination
which is important before decision of
surgical strategy. HRCT provides the
surgeon about possibility of normal
anatomic variation that may be present
such as overriding jugular bulb;
alerting him before start surgery hence
avoids intra-operative problems.
Early use of HRCT in cases of chronic
suppurative otitis media can save
hearing and improve morbidity.
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‫الملخص العربي‬
26
‫" دور األشعة المقطعية بالكمبيوتر( عالية التميز) فى تقييم حاالت التهاب األذن الوسطى المزمن المتقيح‬
‫المصحوب بالورم الزهمي (كوليستياتوما) ومضاعفاته مع مقارنة الدراسة بالجراحة"‬
‫*‪-‬د‪.‬عادل محمد سامي‪ -‬د‪.‬يحيي الكاشف**‬
‫*قسم األشعة التشخيصية‪**-‬قسم األنف واألذن والحنجرة‬
‫مستشفي المنيا الجامعي‬
‫يعتبر التهاب األذن الوسطى المزمن من األمراض الشائعة فى العالم بشكل عام و فى بالدنا بشكل‬
‫خاص ما زال يمثل مشكلة لدى الفئة العمرية من ‪ 01‬إلى ‪ 01‬عاما‪ ,‬حيث يؤدى التهاب األذن الوسطى المزمن‬
‫مع وجود كوليستياتوما (الو رم الزهمى ) إلى تدمير ملحوظ لعظام األذن الوسطى مما يؤدى إلى فقد ميكانيكية‬
‫السمع و كذلك التأثير المباشر على األذن الداخلية و العصب السابع و فى بعض الحاالت تكوين خراج داخل‬
‫المخ‪.‬‬
‫وكان الهدف من هذا البحث تقييم دور األشعة المقطعية بالكمبيوتر( عالية التميز) فى تشخيص وتقييم‬
‫حاالت التهاب األذن الوسطى المزمن المصاحب بالورم الزهمى "كوليستياتوما" ومتابعة الحاالت بعد العمليات‬
‫الجراحية لمعرفة التغيرات المصاحبة ومقارنة نتائج األشعة المقطعية مع نتائج العمليات الجراحية‪.‬‬
‫و قد أجريت هذه الدراسة فى الفترة من سبتمبر ‪ 1110‬حتى ديسمبر ‪ 1110‬فى وحدة األشعة المقطعية‬
‫بالكمبيوتر بمستشفى المنيا الجامعى وقد اشتمل هذا البحث على ‪ 01‬مريض تم اختيارهم من الحاالت المحولة‬
‫من قسم األنف واألذن والحنجرة بالمستشفى الجامعى تراوحت أعمارهم ما بين عشرة الى خمسة وستين عام ‪,‬‬
‫وكان من بين هؤالء خمسة عشرة مريضا من الذكور وسبعة عشرة من اإلناث‪ .‬وقد تم فحص جميع الحاالت‬
‫فحصا إكلينيكيا كامال شمل األعراض المصاحبة لحاالت التهاب األذن الوسطى مثل الصديد المزمن‪ ,‬الفقد‬
‫الجزئى أو الكلى للسمع التوصيلى ‪ ,‬ارتفاع درجة حرارة المريض مع شعوره بالصداع الشديد المصاحب‬
‫اللتهاب األذن الوسطى أو أعراض شلل العصب السابع‪.‬‬
‫تم أجراء األشعة المقطعية عالية التميز على العظم الصدغى لجميع الحاالت فى الوضع المحورى والتاجى‬
‫عن طريق أخذ مقاطع متجاورة سمك المقطع ‪ 0‬ملليمتر باإلضافة الى فحص المخ لبيان المضاعفات المصاحبة‪,‬‬
‫وقد أستخدم وسيط التباين فى بعض الحاالت المصحوبة بالمضاعفات وكذلك فى األورام‪ .‬وقد أثبتت هذه‬
‫الدراسة أهمية استخدام الوضعين‪ ,‬المحورى والتاجى‪.‬‬
‫أكدت هذه الدراسة على النتائج التالية‪-:‬‬
‫لألشعة المقطعية بالكمبيوتر دورا رئيسيا ال غنى عنه فى تشخيص حاالت التهاب األذن الوسطى‬
‫ومضاعفاته وذلك على أن يتم الفحص فى وضعين مختلفين على األقل (مثل الوضع التاجى والمحورى)‪.‬‬
‫معرفة الوصف التشريحى الطبيعى باألشعة المقطعية للعظم الصدغى شامال العظم الصخرى يساعد فى‬
‫التشخيص الدقيق واالستفادة األكبر من الفحص‪.‬‬
‫فى حاالت التهاب األذن الوسطى المزمن المصحوب بالورم الزهمى "كوليستياتوما" أثبتت األشعة‬
‫المق طعية أنها الفحص الفريد فى تقييم تلك الحاالت بدقة متناهية وكشف اإلصابة المبكرة وكذلك توضيح وجود‬
‫الورم الزهمى فى الجزء الخلفى من األذن الوسطى بالفجوات والدهاليز الخلفية بعيدا عن مجال الرؤية بمنظار‬
‫األذن و كذلك أظهرت األشعة المقطعية مكان اإلصابة بدقة وطريق ومدى انتشارها‪ .‬وأثبتت هذه الدراسة‬
‫التناسق الرائع بين تقييم األشعة المقطعية لحاالت الورم الزهمى "كوليستياتوما" قبل أجراء الجراحة والتقييم‬
‫الجراحى لتلك الحاالت‪ .‬كما لألشعة المقطعية دورا هاما فى رسم الطريقة المثلى للجراحة المناسبة للمريض و‬
‫لها أيضا دورا ال غن ى عنه فى تقييم الحاالت بعد إجراء الجراحة لمعرفة التغيرات المصاحبة والكشف عن بقايا‬
‫أو ارتجاع الورم الزهمى وكذلك المضاعفات المصاحبة للجراحة‪.‬‬
‫استطاعت األشعة المقطعية بالكمبيوتر أن تميز بين الورم الزهمى (الكوليستياتوما) واألورام األخرى التى‬
‫تصيب العظم الصدغى مثل األورام الدموية التى كانت تلزم أخذ عينة جراحية لمعرفتها مما يعرض المريض‬
‫لمضاعفات خطيرة مثل النزيف الحاد ‪.‬‬
‫و أظهرت األشعة المقطعية بالكمبيوتر االختالفات الطبيعية للعظم الصدغى التى تمثل أهمية قصوى‬
‫لجراحى األنف واإلذن مما يفيد فى اختيار األسلوب المناسب للمريض وعدم تعرضه لمخاطر تهدد حياته‪.‬‬
‫‪27‬‬