Transcript CT Cisternogram

Imaging of Skull Base CSF leaks in the
Setting of Idiopathic Intracranial
Hypertension: Pearls and Pitfalls
ASNR 2016 ; eEdE-140
Reddy MN, Baugnon KL, Aiken AH, Hudgins PA
Dept. of Radiology and Imaging Sciences
Division of Neuroradiology, Head & Neck
Disclosures
 MN Reddy : None
 KL Baugnon : None
 AH Aiken : None
 PA Hudgins : None
Purpose
 Review pathophysiology of Idiopathic Intracranial
Hypertension (IIH) & skull base cerebrospinal fluid
(CSF) leaks
 Discuss ideal imaging work up
 Illustrate characteristic imaging findings
 Focus on potential pitfalls
 Describe what the treating physician needs to know
IIH
 Headache Syndrome caused by ↑CSF pressure w/o
underlying cause (such as a mass or hydrocephalus)
 Prevalence: 8.6 cases/100,000
 Probable increasing incidence of IIH given rise in obesity
 F:M = 4:1 – 15:1 Obese women of childbearing age
 Strong correlation w/ obesity (> 70% IIH adults)
 Diagnostic criteria:
 International Classification of Headache Disorders : 2nd Edition
 Originally classified by Dandy in 1937 : 2002 version
 PTCS Criteria
Hoffmann, J & Goadsby PJ. "Update on intracranial hypertension and hypotension." 2013.
Current Opinion in Neurology 26 (3): 240-247.
IIH Pathophysiology
↑ Weight
↑ Intra-abdominal /
↑ Intra-thoracic pressure
↑ Central Venous Pressure
↓ CSF absorption
↑ Intracranial Pressure
Doesn’t explain
Female
Predominance
Associated
with
gynecoid fat
Possible
Hormonal
Influence
Hoffmann J, Goadsby. PJ. Update on intracranial hypertension and hypotension.Current opinion in
neurology 2013:26.3; 240-247.
Imaging Findings of IIH
Empty Sella
Orbital Findings
Skull base Findings
Meningoceles
Cerebral Venous Sinuses
Bidot, Samuel, et al. "Brain Imaging in Idiopathic Intracranial Hypertension."Journal of NeuroOphthalmology 35.4 (2015): 400-411.
IIH and CSF leaks Pathophysiology
↑ Intracranial Pressure
Arachnoid Pits form at Skull
Base
Dural Thinning
Arachnoid Diverticula
Herniate through Dural Defect
Arachnoid Diverticula
Rupture and cause CSF leak
Lloyd, Kristen M., John M. DelGaudio, and Patricia A. Hudgins. "Imaging of Skull Base
Cerebrospinal Fluid Leaks in Adults 1." Radiology 248.3 (2008): 725-736.
Work-up of CSF leaks
 Classically present with rhinorrhea or otorrhea
 May present with low pressure headaches, pneumocephalus or
meningitis
 First step is to confirm the presence of a leak with
 In setting of intermittent leaks, fluid can be collected over the
course of a week and stored at room temperature
 β trace protein is another marker with reports of higher
sensitivity and specificity for CSF than β2-transferrin
Imaging Findings of CSF leaks
Non-contrast High Resolution CT
• Look for osseous skull base defect
CT Cisternogram with Intrathecal Contrast
• Extracranial pooling of intra-thecal contrast adjacent to osseous
defect in patient with an active leak
MR Cisternogram
• Assess for encephalocele / meningoencephalocele
MR Cisternogram with Intrathecal Contrast
• Improved contrast resolution, may see delayed leaks
Radionuclide Cisternogram
• Nuclear Medicine study to confirm presence of leak
Algorithm for
Work-up of CSF leak
Positive
B2transferrin
Negative
Unable to
collect fluid
HRCT
No
imaging;
unlikely to
be CSF
leak
HRCT
Multiple
osseous
defects
CT
Cisternogram
Suspect
Meningoencephalocele
MR
Cisternogram
Single
osseous
defect
No further
imaging; most
likely site of
CSF leak
MR Cisternogram,
consider Intrathecal
contrast if high suspicion
Challenges and Potential Pitfalls
 Patients may present with pneumocephalus, middle ear effusion, or
meningitis without rhinorrhea therefore fluid cannot be tested for β2
transferrin
 Presence of multiple osseous defects and/or meningoceles complicates
determining which site is actively leaking
 CT & MR Cisternogram may be negative in absence of an active leak
 Evaluation of a re-leak in post-operative patients is difficult because
opacification from post operative granulation tissue / graft cannot be
reliably differentiated from CSF
 Performing lumbar punctures for cisternography on obese patients (not
infrequently encountered in IIH) may be technically challenging
Case 1
70 year old female s/p repair of left
frontal encephalocele
presents with left sided clear rhinorrhea
Case 1
What would
you do first?
Test fluid for
β2transferrin
Positive
What would
you do
next?
HRCT
2 sites of osseous defects:
Left ethmoid roof & Left frontal sinus
Abnormal soft tissue in the left frontal sinus,
presumably at the site of prior surgical
repair, which may be granulation tissue.
What would
you do
next?
NOTE: Anterior skull base arachnoid pits and
scalloping suggestive of underlying IIH
CT Cisternogram
CT Cisternogram shows asymmetric washout of contrast from the left
frontal hygroma indicative of a left sided CSF leak
Pre-contrast
CT Cisternogram
Contrast pooling within the left frontal
sinus confirms the site of leak.
No change in attenuation was seen
at the left ethmoid roof defect.
Post-contrast
What the surgeon needs to know?
 Patients with IIH may have multiple potential sites of leak on
non-contrast HRCT due to predisposition to skull base defects
 Not uncommon for patients to leak at a different location after
one site is repaired
 Must thoroughly assess the entire skull base, including tegmen,
for possible sites of leak
 Re-leak at the site of surgery is also possible and even more
challenging to assess due to pre-existing granulation tissue
 Important to compare pre and post contrast images side by side
Case 2
68 year old female presents with
meningitis x 2
Intermittent rhinorrhea by history and
bilateral middle ear effusions by exam
Case 2
What would
you do first?
Unable to
collect fluid for
β2-transferrin
High suspicion
for
intermittent
leak
What would
you do
next?
HRCT
Large defect of right tegmen
tympani and tegmen mastoideum
with adjacent abnormal soft tissue
Similarinfindings
on leftear and
opacification
the middle
mastoid cavity.
Case 2
Presentation of
recurrent
meningitis
Unable to test for
β2-transferrin,
yet high
suspicion
HRCT shows
multiple osseous
defects with
adjacent opacity
What would
you do
next?
Hint: PRESENCE OF MASTOID EFFUSIONS MAY
OBSCURE UNDERLYING MENINGOCELE
MR Cisternogram
On the right there
is herniation of
intra-cranial
contents into
middle ear and
mastoid cavity,
diagnostic of a
meningoencephalocele.
Note vertical CSF
cleft and gliosis of
cortex (arrow).
Compare to the
left, where brain
parenchyma
clearly remains
intracranial
adjacent to
osseous defect
What the treating physician needs to
know?
 Bilateral CSF leaks along tegmen tympani / mastoideum,
although unable to confirm with β2 transferrin
 Right side likely a meningoencephalocele
 Report dimensions of defects in multiple planes bilaterally so
surgeon may plan size of dural patch
 Not all meningoencephaloceles are repaired but this patient
had recurrent meningitis, therefore needs repair (likely staged,
right side first)
Case 3
40 year old female with left middle ear
effusion and rhinnorhea confirmed with
β2-transferrin
What would
you do
next?
HRCT
*
Cross reference lines and * show location of
geniculate fossa which is enlarged, and
communicates with middle ear soft tissue
and tegmen via a linear tract
Left side: HRCT shows polypoid
nondependent soft tissue within
medial epitympanic space w/
multifocal dehiscence of tegmen
tympani
MR Cisternogram
Coronal T2-w images through middle
ear shows defect of tegmen tympani
? meningocele
Coronal 3D-FSPGR images confirms
meningocele and show a linear CSF cleft
from meningocele to geniculate fossa
What the surgeon needs to know?
 Left middle ear cavity meningocele, small, with
communication to geniculate fossa
 In surgery, an active peri-geniculate CSF leak was found
 Linear “clefts” or tracts of communication should be followed
to determine complete extent of the meningocele
 Thin section heavily T2w images (i.e. CISS, FIESTA, SPACE) helpful
 Specify involvement of discrete structures such as facial
nerve canal or semi-circular canals
Case 4
50 year old morbidly obese male with
vision changes and clear rhinorrhea
confirmed with β2-transferrin
BMI 54
What would
you do
next?
HRCT
Imaging features were compatible with IIH
Note multiple skull base defects
including large osseous dehiscence in
right anterior skull base and left lateral
sphenoid wall.
Adjacent polypoid soft tissue densities
were concerning for meningoceles.
Which one is leaking?
Patient is too large for the
MRI or fluoroscopy tables
What would
you do
next?
CT guided Lumbar Puncture for CT
Cisternogram
 Administer intrathecal contrast using CTfluoroscopy for image guidance
 In obese patients lumbar puncture can be
technically challenging
 Traditionally, 22 gauge 3.5-inch length needles
are used for obtaining access
 5-inch and 7-inch needles can also be used but
difficult to steer
 18 gauge 3.5 inch needles are sometimes used
as a guide to help steer longer needles using
coaxial technique
7”
5”
3.5”
 Can be helpful to measure opening pressure to
diagnose/confirm IIH at time of procedure –
however ICP may normalize when patients leak
CT Cisternogram
Given multiple areas of osseous
dehiscence, CT cisternography
confirmed active leak in right
anterior skull base, which was
subsequently repaired. There was
no active leak at left sphenoid wall.
What the surgeon needs to know
 Determining which location is actively leaking can be helpful in
IIH pts with multiple osseous defects / meningoceles
 Many of these patients undergo staged repair, treating most
suspicious site first
 Findings can occasionally be confirmed intraoperatively by
intrathecal fluorescein dye
 Options for diagnosis are occasionally limited in this patient
population due to obesity
SUMMARY
 IIH has characteristic radiologic features that can be seen on
both CT and MRI imaging
 Skull base CSF leaks without or with meningoceles are
common complications of IIH but there are imaging pitfalls
 Workup should start with β2 transferrin testing and HRCT
 CT / MR Cisternogram can be helpful when there are multiple
potential sites of leak, suspected meningocele or intermittent
leaks
 Obesity can complicate imaging workup and diagnosis
SUMMARY
 Surgeons need to know:
 Presence of imaging features suggestive of IIH
 Location and size of defects measured in multiple planes –
scrutinize entire skull base including sinuses and mastoids
 Anatomy of sinonasal cavity (i.e. nasal septal deviation,
perforation, variants) for surgical planning / approach
 Associated meningoencephalocele(s)
 Site(s) which is (are) actively leaking
 Entire course of meningocele tract (Heavily T2w images & CT)