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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4416_Библиотеки_им_академика_М_И_Перельмана
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Section 4 Trauma234
A
C
E
Figs. 17.22A to F
B
D
F
ILLUSTRATIVE CASE IN A REPORTING FORMAT
Structures Involved
Table 17.6
Frontal sinus
- Anterior table
- Posterior table
Sinus oor
- Frontonasal duct
Sinus opacication
Sinus expansion
Ethmoid sinus and bone
- Sinus septae
- Cribriform plate
Fovea ethmoidalis
Orbit
Medial wall (lamina
papyracea)
- Lateral wall
- Roof
- Floor
- Optic canal
Superior orbital ssure
Inferior orbital ssure
Maxillary sinus
- Anterior wall
- Roof
- Posteromedial wall
Posterolateral wall
Pterygoid plates
Pterygopalatine fossa
(N: Normal; F: Fracture; if displaced add D; O: Obstructed).
RT LT
N N
N N
N N
N N
N N
N N
N N
N N
N N
F N
F N
N N
F N
N N
N N
N N
O
F N
F N
N N
F N
N N
N N
Sphenoid sinus
- Anterior wall
- Roof
Posterior wall
Zygomatic bone
- Arch
Zygomaticomaxillary suture
Mandible
Condyle
- Ramus
Symphysis menti
Nasal cavity
Turbinates (superior,
middle, inferior)
- Nasal septum
Nasal bone
Intracranial complications None
235Chapter 17 Imaging in Sinonasal Trauma
RT LT
N N
N N
N N
N N
F N
N N
N N
N N
N N
N N
REFERENCES
1. Winegar BA, Murillo H, Tantiwongkosi B. Spectrum of critical imaging ndings in
complex facial skeletal trauma. Radiographics. 2013;33(1):3-19.
2. Avery LL, Susarla SM, Novelline RA. Multidetector and three-dimensional
CT evaluation of the patient with maxillofacial injury. Radiol Clin North Am.
2011;49(1):183-203.
3. Markowitz BL, Manson PN. Panfacial fractures: organization of treatment. Clin
Plast Surg. 1989;16(1):105-14.
18
CHAPTER
Imaging of
Cerebrospinal Fluid Leaks
Atin Kumar, Ajay Garg
• Introduction
• Clinical and Laboratory Workup
• Clinical Course
• Role of Imaging
• Imaging Modalities
– Plain High-resolution Computed
Tomography Skull Base
▪ Role
▪ Technique
▪ Findings
▪ Pitfall
– Computed Tomography
Cisternography
▪ Role
▪ Technique
▪ Findings
▪ Pitfalls
▪ Disadvantages
– Magnetic Resonance
Cisternography (Plain)
▪ Role
▪ Technique
▪ Findings
▪ Pitfalls
– Contrast Magnetic Resonance
Cisternography
▪ Role
▪ Technique
▪ Findings
▪ Advantages
▪ Pitfall
– Radionuclide Cisternography
• Etiology
– Accidental Trauma
– Iatrogenic Trauma
– Secondary Leaks
– Spontaneous Leaks
• Protocol for Evaluation
INTRODUCTION
■ Cerebrospinal uid (CSF) leak or stula is an abnormal communication
of the sterile subarachnoid space with the sinonasal, sphenoid or
tympanomastoid cavities caused by the presence of both an osseous and
a dural defect.
■ It presents clinically with rhinorrhea or otorrhea.
■ It may allow the ora of the sinonasal cavity or the middle ear to spread
to the intracranial compartment and lead to meningitis.
■ Hence, it requires an early diagnosis and timely repair.
CLINICAL AND LABORATORY WORKUP
■ Rule out other causes of nasal discharge such as allergic rhinitis, polyps,
sinusitis or tumors.
■ Biochemical examination of uid for beta-2 transferrin levels which is a
highly specic protein for CSF. If facility for testing is not available, then
indirect method of conrmation of CSF is by evaluation of glucose and
protein levels.
CLINICAL COURSE
■ Most of the acute leaks resolve spontaneously with conservative management, sometimes aided by decreasing CSF pressure by a lumbar or
external ventricular drain.
■ Surgery required for nonhealing, long duration leaks (usually more than
7–10 days) or for associated conditions
■ Imaging required as a preclude for surgery.
ROLE OF IMAGING
■ To localize the exact site of the leak.
■ To diagnose any associated condition such as a tumor or encephalocele.
■ To provide a roadmap for surgery.
237Chapter 18 Imaging of Cerebrospinal Fluid Leaks
IMAGING MODALITIES
Plain High-resolution Computed
Tomography Skull Base (Figs. 18.1A and B)
Role
■ is is the rst line of imaging and has an excellent accuracy with a
sensitivity of 84–95%.
■ Best investigation to exactly delineate the defect as well as the surgical
anatomy for planning and guidance.
■ Can be done even when the patient is not actively leaking.
Technique
■ High-resolution thin sections through the face and skull base including
the mastoids in supine position.
■ Multiplanar reformats done in coronal and sagittal plane.
Findings
■ Detects site of bony defect or fractures.
Indirect signs include pneumocephalus, meningoencephaloceles and uid
in paranasal sinuses just beneath the site of defects.
Pitfall
■ e bony defect detected may not be associated with a dural defect.
Section 4 Trauma238
A B
Figs. 18.1A and B: Normal high-resolution computed tomography (HRCT) skull base.
Coronal reformatted CT image (A) (magnied in B) shows cribriform plates (dotted arrows)
are joined to the roof of ethmoids (fovea ethmoidalis) (white arrows) by a thin bone of lateral
lamella.
Computed Tomography Cisternography (CT Cisternography)
Role
■ It is the most accurate method for investigation of active CSF leak with a
sensitivity of 72–81% for detection of leaks.
■ It is done when the patient is having an active leak.
■ Considered as a gold standard.
■ Done in cases where there are multiple fractures.
Technique
■ Cotton pledgets are placed in both nostrils of the patient.
■ Take initial precontrast thin section multidetector computed tomography.
(MDCT) in prone position.
■ Perform lumbar puncture with adequate sterile precautions.
■ Instill 10 mL of iodinated nonionic contrast (Iohexol) under uoroscopic
guidance.
■ Keep the patient in reverse Trendelenburg position for 15 minutes to
allow the contrast to reach cranium and distribute freely.
■ Obtain thin sections computed tomography (CT) of skull base in coronal
plane with patient lying prone (Figs. 18.2A and B).
Findings
■ Cerebrospinal uid leaks are seen as areas of contrast pooling in the
paranasal sinuses or nasal cavity adjacent to the site of defect.
■ Often the direct contrast column is seen extending through the bony
defect.
■ Can measure Hounseld unit values in suspected regions and compare
with precontrast images–a 2-fold increase in attenuation conrms the
leak.
A B
Figs. 18.2A and B: Normal CT cisternography. (A) Coronal and (B) Sagittal reformatted
images. The contrast is seen to opacify the sulcal spaces within the intracranial compartment
with intact base of skull. No contrast is seen to leak into the nasal cavity or paranasal sinuses.
■ If doubtful, repeat localized section with change in patient position. e
contrast will change in position.
■ If high ow leak is present, the intracranial contrast may show a washout
in the ipsilateral compartment.
■ Change in position of contrast with change in patient position
■ Soue eect.
239Chapter 18 Imaging of Cerebrospinal Fluid Leaks
Pitfalls
■ Low ow stulas or thin hairline fractures may not be demonstrated due
to higher viscosity of contrast.
■ Inadequate contrast distribution in region of interest either due to
improper technique or adhesions in subarachnoid space secondary to
bleed.
■ Dicult to appreciate small amount of dilute contrast medium adjacent
to a surrounding bony structure or sometimes highly dense contrast
which mimics bone.
Disadvantages
■ High radiation.
■ Risks associated with lumbar puncture.
■ Adverse reactions to contrast.
Magnetic Resonance Cisternography (Plain)
(MR Cisternography) (Fig. 18.3A)
Role
■ A nonradiating and noninvasive method with a sensitivity of 94% for
detecting leaks.
Section 4 Trauma240
■ It is good for characterization of the contents of the leak–can diagnose
meningoencephaloceles by detecting meninges and brain tissue within.
Intravenous contrast can be helpful for seeing dural enhancement in
case of suspected meningoencephalocele.
Technique
■ Predominantly utilizes heavily T2-weighted 3D sequences [constructive
interference in steady-state (CISS) or driven equilibrium (DRIVE) or fast
imaging employing steady-state acquisition (FIESTA)]
■ Done in prone position.
Findings
■ Detects leak as a hyperintense signal intensity within the paranasal
sinuses in continuation with CSF with an overlying defect at the bonedura interface.
■ e signal of the leak is matching that of the CSF. e signal of uid due
to rhinosinusitis, if present, is usually slightly less hyperintense and does
not parallel that of CSF.
■ Herniation of brain content can also be detected.
Pitfalls
■ Indirect method of detecting leaks as uid intensity in the sinuses is
presumed to be of CSF.
■ Sometimes dicult to dierentiate from secretions in sinuses.
Contrast Magnetic Resonance Cisternography (Fig.18.3B)
Role
■ is is performed with intrathecal administration of MR contrast agent
and has a sensitivity close to 100% for high-ow leaks.
■ Used as a problem solving tool as o-label use of gadolinium contrast.
Technique
■ About 0.5–1 mL of intrathecal gadolinium contrast (Gd-DTPA) injected
after lumbar puncture followed by same positional maneuvers as in CT
cisternography.
■ Magnetic resonance (MR) is typically done after an hour of intrathecal
contrast administration. However, the window for imaging is reported to
be up to 24 hours.
■ T1-weighted 3D sequence is obtained in coronal plane with patient lying
prone.
Findings
■ Shows CSF leaks as continuous column of hyperintense signal CSF on
T1 image from intracranial compartment to within the paranasal sinuses
through the defect in bone-dura interface.
A B
Figs. 18.3A and B: (A) Normal plain magnetic resonance cisternography; and (B) Con trast
magnetic resonance cisternography. Coronal reformatted images. The constructive
interference in steady-state (CISS) sequence shows: (A) the hyperintense cerebrospinal uid
in sulcal spaces limited to the intracranial compartment. In the contrast study (B) gadolinium
is seen to opacify the sulcal spaces within the intracranial compartment with intact base of
skull on this T1 weighted coronal MR image. No contrast is seen to leak into the nasal cavity
or paranasal sinuses.
241Chapter 18 Imaging of Cerebrospinal Fluid Leaks
Advantages
■ Nonradiating
■ Better than plain MR cisternography for detection.
■ Lower dosage and better CSF distribution of contrast compared to CT
cisternography.
■ Contrast stays longer in CSF. Hence, imaging can be done up to
24 hours–helps to detect intermittent leaks.
Pitfall
■ Safety of the intrathecal contrast not well established–not approved
by the United States Food and Drug Administration for potential risk
of neurotoxicity. However, many European studies have shown no
signicant adverse eects with o-label use.
Radionuclide Cisternography
■ Performed after intrathecal administration of technitium-99 labeled
diethylenetriaminepentaacetic acid (DTPA).
■ e radioactivity is measured after 24–48 hours in the pledgets placed in
the nasal cavity for conrming presence of CSF leak.
■ More helpful for conrming presence of CSF leak and not so good for
detection of site of leak.
■ Rarely used now in clinical practice.
Section 4 Trauma242
ETIOLOGY
e numerous causes of CSF rhinorrhea are:
■ Trauma: accidental or iatrogenic
■ Secondary leaks
• Tumor related
• Congenital defects
• Postradiation or chemotherapy
■ Spontaneous leaks.
Accidental Trauma (Figs. 18.4 to 18.6)
■ It is the most common etiology seen in 10–30% of all skull base fractures.
■ e patients present early within the rst few days.
■ Most common sites—cribriform plates, ethmoid roof, frontal sinus,
sphenoid sinus, tegmen tympani.
■ Cerebrospinal uid may leak into the sinonasal cavity (in frontobasal
fractures) or into the middle ear cavity and mastoid air cells (in temporal
bone trauma).
■ Acute CSF rhinorrhea (80%) or otorrhea is the usual clinical presentation.
■ Most posttraumatic CSF leaks heal spontaneously with conservative
management.
■ Meningitis may be seen in up to 50% of cases, if the leak does not resolve
spontaneously or is not repaired.
■ Persistent leaks for longer than 7–10 days, in spite of CSF diversion,
require intracranial or endoscopic repair.
■ Larger skull base defects (>1.5 cm) or severely comminuted fractures,
with meningoencephalocele, also require surgical repair.
A B
Figs. 18.4A and B: Fracture anterior skull base. (A) Coronal and (B) Sagittal reformatted
high-resolution computed tomography skull base images in an 18-year-old male with road
trafc injury shows a bony defect at the right ethmoid roof (arrows) with uid density seen in
ethmoid sinus just beneath the defect.
243Chapter 18 Imaging of Cerebrospinal Fluid Leaks
A
B
C
Figs. 18.5A to D: Traumatic cerebrospinal uid rhinorrhea. (A and B) CT cisternography––
bony defect at the left ethmoid roof with contrast column extending from intracranial
compartment to the ethmoid sinus; (C and D) Contrast MR cisternography––conrms the
ndings of CT.
D
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