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Fig. 45.1 Normally pneumatized mastoid—conventional radiography—Schüller
1 view
fossa. Their experiences were summarized and published
in 1966 in a book on temporal bone tomography and in
1973in an atlas [2].
An important historic achievement came in 1972 with
the introduction of CT by Godfrey Hounsfield of Great
Britain, who was a computer specialist. The foundation
of CT was based on mathematical equations that had
been formulated in 1963 and 1964 by AM Cormack, a
professor of physics at Tufts University in Boston. In
1979, both researchers were awarded the Nobel Prize in
Medicine for this remarkable discovery. CT has allowed
the differentiation of normal and abnormal soft tissues
and bone structures and its development in recent years,
through helicoidal CT, has allowed rapid examinations
and thinner cuts, with the ability to reconstruct
three-dimensionally.
A third important milestone in radiology occurred with
the introduction of MRI.The principles of this examination
are based on the theory of spin and were rst demonstrated
by Isidor Rabi in 1938 [3, 4], who tested the emission of a
particle beam through a magnetic eld and showed that it can
emit waves at dependent frequencies and the charge of the
particles and the strength of the magnetic eld. In 1946,
Bloch and Purcell [3, 5–7] demonstrated the same principles
applied to liquids and solids and, in 1978, Young and Clow
[3, 8] obtained the rst magnetic resonance imaging of the
M. N. L. da Silva et al.
brain, enabling the development of neuroanatomical studies
in a unique way.
Computed Tomography ofTemporal Bones
CT is an excellent exam to evaluate the structures of the temporal bone [9], as well as the changes caused by otitis media.
The cuts must be 1–2mm thick and the images presented in
the axial, sagital, and coronal planes, being the images carefully evaluated in windows for bone, soft tissue and liquid.
Its use is becoming more and more indicated, especially in
surgical cases, because through it, the diagnosis can be conrmed, the involvement of the ear by the disease can be accurately measured and the surgical team prepared for possible
anatomical variations capable of complicating a surgery.
The COM presents alterations well described in the tomographic studies. It is possible to visualize the presence of
effusion in the middle ear and mastoid, bone erosions, degree
of pneumatization mastoid, position of the lateral sinus and
the relationship between the temporal bone and the great
vessels [10]. In addition, modern helicoidal image acquisition techniques and high-resolution slices allow the evaluation of smaller structures more accurately. The state of the
tympanic membrane, the ossicular chain, and the entire
course of the facial nerve can be estimated. However, often
some structures are not carefully observed through this
exam, mainly due to the lack of standardized routine of analysis. Thus, the systematic use of this test in the evaluation of
patients with cholesteatoma is essential.
Currently, there are no reasons to dismiss CT. It has a
much lower cost than in the past, rapid performance and
minimal morbidity. The minimum assessment includes mastoid pneumatization, opacications, facial nerve path, teg-
men position, bone erosions, ossicular chain, relationship of
the great vessels and sigmoid sinus, aeration of the protympanum, bone spur of Chaussé, and anatomical variations [11,
12]. It is important to standardize a “check list” (Figs.45.2
and 45.3) so that there is no risk of neglecting any structure
or compartment, avoiding surprises during the operation.
The gures presented show the characteristics considered
the most important in the radiological analysis in the axial
and coronal planes of temporal bones [12]. The structures
and form of evaluation are described in Tables 45.1, 45.2,
45.3, and 45.4.
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Fig. 45.2 List of structures
seen in the axial plane
Fig. 45.3 List of structures
seen in the coronal plane
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Table 45.1 Radiological interpretation of structures
Coronal plane Axial plane Evaluation
External auditory canal At the level of the basal turn of the
cochlea and the IAC—Fig. 45.4
Tympanic membrane At the same level as the EAC, head,
neck, and proximal part of the
malleus manubrium—Fig. 45.4
Mesotympanum Sections between the cochlea
(anterior) and the IAC (posterior)
Protympanum – At the level of the basal turn of the cochlea.
Retrotympanum – On the same level as the pro-tympanum.
Epitympanum Sections between the cochlear turns
and the facial nerve section at the
second genu (anterior) up to the
SSCC view (posterior)– Fig.45.8
Bone spur of Chaussé
and prussak space
Lateral semicircular
canal (LSC) and
superior semicircular
canal (SSC)
Tympanic tegmen Along the entire length of the middle
Intrapetrosal carotid
artery
Jugular bulb Inferior to the cochlea and
Cortical bone of the
posterior fossa
Sigmoid sinus – At the mastoid and posterior fossa levels—
Petrous apex – At the Internal Auditory Canal level—Fig.
Cochlea – Figure 45.20a Malformations, erosions, or
Internal Auditory Canal
(IAC)
Level of the cochlear turns, in the
transition to the labyrinth, with
observation of the malleus head and
neck—Figs. 45.8 and 45.10
Between the levels of the
epitympanum (anterior) to the
mastoid antrum (posterior)—Fig.
45.11
ear and mastoid. From the beginning
of the cochlea (anterior) to the most
posterior regions of the mastoid—
Figs. 45.13 and 45.14
– From its vertical (lower) portion and its
labyrinth—Figs. 45.16 and 45.17
– At the level of the lateral sinus cut—Fig.
– Figure 45.20b Sign of enlargement, possible
At the level of the basal turn of the cochlea,
the TMJ (anterior) and the mastoid cells
(posterior) are visualized—Fig. 45.5
At the same level as the EAC, sections
showing the posterior recesses—Fig. 45.5
Level between the basal turn of the cochlea
(lower) to the appearance of all the turns
(upper) —Fig. 45.6
Previous: TMJ.Posterior: carotid canal and
anterior portion of the otic capsule—Fig.
45.7
Facial nerve in second genu (between
tympanic and mastoid segments) divides
posterior recesses into sinus tympani
(medial)
and facial nerve recess (lateral)– Fig.45.7
showing the incudomalleolar joint—Fig. 45.9 Aeration or lled
– Bone Spur of Chaussé: Intact
The LSC can be visualized in the section that
shows the cochlea and the modiolus, in
addition to the incudomalleolar joint—Fig.
45.12
– Integrity and position
relations with the hypotympanum and jugular
foramen, to its horizontal (upper) portion and
its interaction with Eustachian tube—Fig.
45.15
Posterior to the carotid artery, at lower levels Normal, dehiscent, or salient
45.18
Fig. 45.18
45.19
Normal, eroded, or lled with
material (soft tissue or bone)
Normal, retracted, perforated,
thickened or with
tympanosclerosis— Fig.45.4
Aeration or lled
Aeration or lled
Aeration or lled
or eroded .
Prussak space: compartment
between Chaussé and the
malleus head. Aerated or
veiled.
Integrity or presence of
labyrinthine stulas.
Normal, dehiscent or salient.
Integrity
Normal, dehiscent, or salient
Pneumatized or not. Evaluate
pathologies such as effusion,
destruction of septa or tumors
calcications
invasion by cholesteatoma or
tumors.
M. N. L. da Silva et al.
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Table 45.2 Radiological interpretation of the ossicular chain: malleus,
incus, and stapes
Ossicular chain
Malleus
Head (Fig.45.21a, b) Coronal plane (Fig.45.21a): at the level of
Prussak’s space.
Axial plane (Fig.45.21b): in the region of
the epitympanum, at the level of the
horizontal segment of the facial nerve, the
IAC and the LSC
Neck (Fig.45.22a, b) Coronal plane (Fig.45.22a): at the level of
bone spur of Chaussé.
Axial plane (Fig.45.22b): section showing
the cochlea with the modiolus
Handle (Fig.45.23) Coronal plane: section where the TM, the
cochlea and the transversal section of the
facial nerve (labyrinthine and tympanic
segments) can be observed
Evaluation Normal, eroded, absent or involved by
tympanosclerosis (Fig.45.24)
INCUS
Body (Fig.45.25) Axial plane: intermediate level between
the head and neck of the malleus, in the
section where the cochlea and LSC can be
seen. It is possible see the short process
Long process and
incudostapedial joint
(Figs.45.26 and 45.27)
Evaluation Normal, eroded, absent, or involved by
Stapes
Coronal plane
(Fig.45.27)
Axial plane (Fig.45.26) Level where the cochlea, vestibule, IAC,
Evaluation Normal, eroded, absent, or involved by
Viewed with the stapes
tympanosclerosis
Level where the vestibule, basal turn of the
cochlea, LSC and SSC are observed
and petrous apex are observed
tympanosclerosis
Table 45.4 Radiological interpretation of the facial nerve
Facial nerve
Tympanic segment
(Figs.45.32 and
45.33)
Mastoid segment
(Fig.45.32)
Evaluation Normal or eroded bone canal, dehiscent
Fig. 45.4 Coronal plane. Comparison between the two ears. Right ear
with normal TM and external auditory canal without alterations (left
side arrow). Left ear with perforated TM and presence of soft tissue
material in the external auditory canal (right side arrow)
Axial plane: the entire course, including the
rst genu, at the level of the
incudomalleolar joint.
Coronal plane: cross section under the LSC.
Coronal plane: at the level of the
stylomastoid foramen, inferior to the LSC.
nerve or not.
Table 45.3 Radiological interpretation of the mastoid
Mastoid
Coronal plane
(Fig.45.27)
Axial plane
(Fig.45.26)
Evaluation It is classied as sclerotic, diploic, or pneumatized
Level where the vestibule, basal turn of the
cochlea, LSC and SSC are observed
Level where the cochlea, vestibule, IAC, and
petrous apex are observed
(Figs.45.28, 45.24, 45.29, 45.30).
Sclerosis: absence of pneumatization.
Diploic: 10 or fewer cells between 2 and 5mm in
size, plus a pneumatized antrum. Mastoids with
partial pneumatization .
Pneumatized: completely aerated, with more than
10 cells of the size mentioned above, in addition to
a pneumatized antrum.
Then it is divided into 3 spaces: antrum, tip, and
“mid” . mastoid” (intermediate region).
Presence or not of veiling in each space
(Fig.45.31)
Fig. 45.5 Left ear axial plane. Tympanic membrane (arrow) and EAC
(asterisk)
Based on this suggested systematization (Figs. 45.34,
45.35, 45.36, and 45.37) and examples of pathological tem-
poral bones, it becomes easier to assess the presence of disease, stage the involvement of the middle ear and mastoid,
and safely propose surgeries through CT of the temporal
bones.
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Fig. 45.6 Left ear axial plane. Round window niche (ellipse)
M. N. L. da Silva et al.
Fig. 45.9 Right ear axial plane: visualization of the incudomalleolar
joint in the epitympanum
Fig. 45.7 Left ear axial plane. Aerated protympanum (short arrow),
aerated mesotympanum (long arrow), and posterior recesses (ellipse).
Note the facial nerve in the center of the ellipse dividing the sinus tympani (more medial) from the facial recess (more lateral)
Fig. 45.8 Right ear coronal plane. Aerated epitympanum (upper
ellipse); free Prussak space, between the lateral wall of the attic and the
ossicular chain (arrow); free hypotympanic cells (lower ellipse)
Fig. 45.10 Right ear coronal plane. Bone Spur of Chaussé (arrow)
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Fig. 45.11 Malleus head (arrows). In (a), right ear coronal plane. In (b), the same ear in the axial plane
ab
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Fig. 45.12 Malleus neck (arrows). In (a), right ear coronal plane. In (b), the same ear in the axial plane
Fig. 45.13 Malleus handle (arrow)
Fig. 45.14 Incus body with a short process (arrow)
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Fig. 45.15 Axial plane of the right ear: visualization of the long process of the incus (arrowhead), stapes (arrow), footplate, and vestibule.
Normal ossicular chain
M. N. L. da Silva et al.
Fig. 45.16 Right ear coronal plane. Incudostapedial joint with visualization of the oval window (ellipse) in the mesotympanum
ab
Fig. 45.17 Axial plane of the right ear of 3 patients: pneumatized mastoid in (a), diploic in (b) and sclerotic in (c)
ab
c
c
Fig. 45.18 Left ear coronal plane: pneumatized and veiled mastoid compartments. (a) Antrum. (b) Mid mastoid. (c) Mastoid tip
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Fig. 45.19 Coronal plane of the right ear: LSC (arrow) and SSC (arrowhead) in view at the level of the epitympanum in (a), the aditus in (b) and
the antrum in (c)
c
Fig. 45.20 Left ear axial plane: LSC (arrow)
Fig. 45.21 Right ear coronal plane. Tegmen timpani (arrow)
Fig. 45.22 Coronal plane—left ear. Tegmen’s erosion (long arrow) and
LSC stula (short arrow). Veiling of the tympanic cavity in the region of
the oval window and epitympanum suggesting cholesteatoma
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Fig. 45.23 Visualization of the facial nerve path. (a) Axial plane, right ear: tympanic segment of the facial nerve and rst genu (arrow). (b)
Coronal plane, left ear: mastoid segment of the facial nerve (F)
M. N. L. da Silva et al.
Fig. 45.24 Visualization of the facial nerve path (arrows)—right ear coronal plane. (a) Cross section of the tympanic segment of the facial nerve.
(b) Cross-section of the labyrinthine (more medial) and tympanic (more lateral) segments
Fig. 45.25 Intrapetrous carotid artery (arrow)
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a
Fig. 45.26 Left ear coronal plane: dehiscent jugular bulb (arrow)
Fig. 45.27 Right ear axial plane: prominent sigmoid sinus, but with
integrity of the posterior fossa cortex (arrow)
b
Fig. 45.28 Axial plane left ear of different patients. View of the
petrous apex (arrows). In (a), cell pneumatization next to the clivus. In
(b), pneumatization of supracochlear cells
Fig. 45.29 Left ear axial plane. (a) Visualization of normal cochlear turns (ellipse). (b) Normal internal auditory canal (arrow)
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