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7/24/2019 Radiologis bedah saraf
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Intracranial Hypertension and Brain Herniation Syndromes
Radiology Cases in Pediatric Emergency Medicine
Volume 5, Case 6
Loren ! "amamoto, M#, MPH
$apiolani Medical Center %or &omen 'nd C(ildren
)ni*ersity o+ Haaii -o(n '! Burns Sc(ool o+ MedicineThis is a 5-year old female who is brought to the
emergency department at 8:00 a.m. because she was
poorly responsive when her mother awoke her in the
morning. This prompted her mother to drive her to the
E.. There is a history of headache and vomiting
during the evening and night. There is no history of
trauma.
E!am: "# T$%.& 'rectal() *+,) $,) * /$&+&.
#he is minimally responsive. *upils e1ual and reactive.
There are no signs of e!ternal trauma. 2ithin minutes of arrival) she e!hibits e!tensor
posturing. #he is orally intubated using the rapid
se1uence induction method with atropine) thiopental)
and vecuronium. #he is hyperventilated. End-tidal
34, monitoring is used to keep her p34, in the ,5
mmg range. 6 loading dose of phenytoin is
administered.
6n emergency 3T scan is ordered.
"iew 3T scan.
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There is obvious bilateral intraventricular
hemorrhage and ventricular dilatation. 3linically)
e!tensor posturing suggests the possibility of impending
herniation. #he sustains episodes of bradycardia which
respond to doses of 7" mannitol. 6 neurosurgeon
decompresses her ventricles immediately. #herecovers well without neurological deficits. #ubse1uent
studies demonstrate the presence of a choroid ple!us
arteriovenous malformation. This is neurosurgically
ablated.
iscussion
7ncreases in intracranial pressure '73*( compress
the brain within the rigid skull. This reduces cerebral
blood flow prompting refle! hypertension to maintain
cerebral perfusion. 6s intracranial pressure increasesfurther) the contents of the skull can no longer remain
in
place. ocal increases in pressure) such as with
tumors and acute hemorrhages) result in focal
deviations in anatomy. 2hile the term 9herniation9 is
used loosely when intracranial pressure increases)
there are specific herniation syndromes with different
mechanisms and outcomes. 7dentifying increases in
intracranial pressure by clinical and radiographic means
is important to intervene early to prevent herniation. 3linical signs and symptoms of acute increased
intracranial pressure include) headache) vomiting) vision
distortion) diminished sensorium) pupillary dysfunction)
hypertension) bradycardia) fle!ore!tensor posturing)
etc. *apilledema may not be present if 73* increases
acutely.
2hen intracranial hypertension is suspected) an
immediate 3T scan should be obtained to assess the
degree of 73* increase and to identify the cause of the
this. The following areas should be assessed on 3T
when attempting to determine the presence and
severity of intracranial hypertension. These are
discussed in more detail below.
/. *rominence of sulcigyri.
,. ateral ventricle si;e.
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$. uadrigeminal cistern.
There are several brain herniation syndromes.
These are discussed in more detail below. /. ?ncal herniation.
,. Transtentorial herniation.
$. Tonsillar herniation.
=. #ubfalcine herniation.
5. #uperior vermian herniation.
3T signs of intracranial hypertension:
/. *rominence of sulcigyri: 2hen intracranial pressure increases) this
compresses the cerebral corte! against the calvarium.
This attenuates the visibility of the sulci and gyri.
6dditionally) the space between the corte! and the
calvarium is minimal when 73* increases.
"iew loss of sulcigyri.
The image on the left is a high 3T cut which should
show the sulci and gyri well. ue to increased 73*) the
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corte! is compressed up against the calvarium losing
the distinctness of the sulci and gyri. The space
between the corte! and the calvarium is obliterated.
The sulcigyri sign cannot be totally relied upon in
some instances. 7n cases of e!ternal hydrocephalus orchronic 'or subacute( subdural effusions) fluid collects
over the corte!. The fluid space between the corte!
and the calvarium appears to be increased and the
sulcigyri may appear prominent.
"iew prominent sulcigyri.
#hown here is a focal e!tra-a!ial hematoma. @ote
the prominent sulci and gyri despite intracranial
hemorrhage.
,. ateral ventricle si;e:
7n acute hydrocephalus) due to obstruction in the
outflow of 3#) the lateral ventricles will be enlarged.
#imilarly) in acute intraventricular hemorrhage) the
lateral ventricles will be enlarged.
"iew dilated ventricles.
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#hown here are bilateral dilated lateral ventriclesdue to acute intraventricular hemorrhage.
7n other causes of intracranial hypertension) the
lateral ventricles will be compressed 'slit-like( or
obliterated due to increases in pressure in
compartments other than the lateral ventricles. This is
the case in generali;ed cerebral edema) subdural
hematoma) epidural hematoma) etc.
"iew compressed ventricles.
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#hown here are two cuts showing subarachnoid
hemorrhage. The ventricles are slit-like due to cerebral
edema and acute hemorrhage resulting in intracranial
hypertension.
$.
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"iew poor greywhite matter distinction.
=. #uprasellar cistern:
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The suprasellar cistern is a fluid-filled space
above
the sella turcica. 7t contains the circle of 2illis and
the
optic chiasm. 4n 3T scan) it has a star-shaped
appearance. 6nteriorly) the top point of the star isformed by the interhemispheric fissure between the two
frontal lobes. The lateral border of the suprasellar
cistern is formed by the uncal portion of the temporal
lobes. The posterior border is formed by the pons in
lower cuts and the cerebral peduncles of the midbrain in
higher cuts. 7n lower cuts where the pons forms the
posterior border of the suprasellar cistern) the
suprasellar cistern takes on the shape of a 5-pointed
star. 7n cuts where the cerebral peduncles 'which have
a central cleft( form the posterior border of thesuprasellar cistern) the suprasellar cistern takes on the
shape of a %-pointed star.
"iew the midline anatomic diagram of the brain.
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This is a midline sagittal cut of an A7 scan. 7dentify
the following structures:
# - suprasellar cistern
*o - pons
* - cerebral peduncles 'midbrain(
A - medulla 3 - 1uadrigeminal plate 'superior and inferior
colliculi(
" - fourth ventricle
> - 1uadrigeminal cistern
@ote that the fourth ventricle is connected to the
third ventricle by the cerebral a1ueduct which is very
thin and may not be visible on 3T.
"iew the anatomic diagram of the suprasellar cistern.
The midline sagittal A7 scan shows the levels of
the a!ial diagrams. @ote that the fourth ventricle is at
roughly the same level of the suprasellar cistern) but
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depending on the angle of the a!ial cut) the fourth
ventricle may be seen in cuts above) below) or at the
same level as the suprasellar cistern. The suprasellar
cistern is seen in cuts & and 8.
7n the lower cut '&() the suprasellar cistern 's(
takeson the shape of a five pointed star. The frontal lobes
'( form the anterior border with the anterior
interhemispheric fissure between the frontal lobes
forming the ape! of the star. The uncus '?( of the
temporal lobes forms the lateral borders. The pons
'*o( forms the posterior border. The fourth ventricle
'"(
is also seen in this cut.
7n the higher cut '8() the suprasellar cistern 's(
takeson the shape of a si! pointed star. The only difference
higher up is that the posterior border is formed by the
cerebral peduncles 'p( of the midbrain. The cleft
between the cerebral peduncles forms the si!th point of
the star. The inferior colliculi 'c( can also be seen at
this level of the suprasellar cistern.
"iew 3T scan of suprasellar cistern.
The left and center images show the suprasellar
cistern. 7ts anterior borders are formed by the frontal
lobes '(. 7ts lateral borders are formed by the uncus
'?( of the temporal lobes. The left image shows the
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5-pointed star appearance of the suprasellar cistern
where the posterior border is formed by the pons '*o(.
The black arrow points to the fourth ventricle. The
center image shows a higher cut where the suprasellar
cistern has a %-pointed star appearance since the
posterior border is formed by the cerebral peduncles'*( which have a central cleft.
2hen 73* increases) the suprasellar cistern space
is compressed. The space may still be visibleB
however) with severe intracranial hypertension) the
cistern is obliterated due to encroachment of brain
tissue that normally forms the borders of the suprasellar
cistern. epending on the cause of the intracranial
hypertension) the suprasellar cistern may be totally
obliterated in global or severe 73* increase. 7n focal
lesions) brain tissue may encroach into only one part ofthe suprasellar cistern. 7n early unilateral uncal
herniation) the uncus of the temporal lobe 'lateral
border of the suprasellar cistern( will protrude into the
suprasellar cistern.
5. >uadrigeminal cistern:
6lso known as the 1uadrigeminal plate cistern) this
fluid filled space is located cephalad to the fourth
ventricle.
"iew the anatomic diagram of the 1uadrigeminal
cistern.
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The midline sagittal A7 scan shows the levels of
the a!ial diagrams. The 1uadrigeminal cistern is
located above 'anterior to( the 9>9 in the highest cut
shown 'number +(. The anterior border of the
1uadrigeminal cistern is formed by the superior colliculi
'c(. 7mage 8 'lower cut( also shows the 1uadrigeminal
cistern. 7n this case) its anterior border is formed by
the
inferior colliculi 'c(. This gives the anterior border
of the
1uadrigeminal cistern the appearance of a 9babyCs
bottom9. The 1uadrigeminal plate is comprised of the
superior and inferior colliculi. The 1uadrigeminal
cistern
is posterior to this 1uadrigeminal plate) thus its
anterior
border may be formed by the inferior or superior
colliculi.
"iew 3T scan of 1uadrigeminal cistern.
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The right image shows the 1uadrigeminal cistern'black arrow(. @ote the 9babyCs bottom9 appearance of
its anterior border. 2hen 73* is increased) the
1uadrigeminal cistern space is compressed or
obliterated.
7dentify the suprasellar and 1uadrigeminal cisterns in
the following e!amples.
"iew moderately increased 73*.
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The suprasellar cistern is slightly smaller than its
normal si;e 'the right uncus is pushing into the
suprasellar cistern( and the 1uadrigeminal cistern is
compressed. 6n epidural hematoma is noted.
"iew severe 73* increase.
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The suprasellar cistern 'left image( is tissue-
filled)
indicating the presence of brain tissue herniating intothis space. The 1uadrigeminal cistern is very
compressed and pushed posteriorly 'center image(.
The suprasellar cistern is located Dust above the base of
the skull 'above the sella(. 7t should be visible in the
cuts near the base of the brain. 7f it is not visible)
it
suggests that the suprasellar cistern is obliterated.
#imilarly) the 1uadrigeminal cistern should be located in
the cut above the suprasellar cistern. 6 subdural
hematoma is noted with a midline shift.
rain erniation #yndromes:
/. ?ncal herniation:
2hen mass effects within or adDacent to the
temporal lobe occur) the medial portion of the temporal
lobe 'uncus( is forced medially and downward over the
tentorium. There is ipsilateral pupillary dilation. The
uncus is pushed medially into the suprasellar cistern.
"iew uncal herniation.
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There is bilateral uncal herniation. Thesuprasellar
cistern is obliterated.
"iew early uncal herniation.
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The right uncus is pushing into the suprasellar
cisternB early right uncal herniation.
,. Transtentorial herniation: 7t should be noted that this term is somewhat vague.
7t is used rather loosely and it may sometimes be used
similarly to the terms temporal lobe herniation and uncal
herniation. The uncus may herniate over the tentorium
as described above. #upratentorial lesions on one side
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may initially result in uncal herniation. 6s 73*
increases
further) bilateral temporal lobe herniation occurs
transtentorially. Early unilateral uncal herniation is
more accurately called uncal herniation. The terms
cranial-caudal transtentorial herniation) rostro-caudaltranstentorial herniation) or central transtentorial
herniation more accurately describe what is generally
meant by 9transtentorial herniation9. Thus) uncal
herniation is described separately above.
7n transtentorial herniation the medial portions of
the
temporal lobes 'uncus( and the brainstem herniate
downward from supratentorial to the infratentorial
compartment. The clinical signs include headache)
decreasing level of consciousness and ipsilateral fi!eddilated pupil 'from compression of the third cranial
nerve on the ipsilateral side(. 6s herniation worsens)
decerebrate 'e!tensor( posturing) contralateral 'ie.)
bilateral( pupillary dilation and 3ushingCs triad occur.
3ushingCs triad includes alteration in respiration)
bradycardia) and systemic hypertension. 7t is rare to
have all three present in children. 4ften there is Dust
bradycardia alone. 3hildren tolerate brainstem
compression produced by herniation better than adults.
7mmediate early intervention can result in recovery.7ntervention at the stage of unilateral pupillary
dysfunction is likely to have a better prognosis
than intervention at the stage of bilateral pupillary
dysfunction) decerebrate posturing and bradycardia.
3T scan shows obliteration of the suprasellar and
1uadrigeminal cisterns. ater findings include infarcts
and brainstem hemorrhage."iew transtentorial herniation.
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The suprasellar cistern 'left image( is obliterated.
The 1uadrigeminal cistern is very compressed and
pushed posteriorly 'center image(. 6 subdural
hematoma with a midline shift is noted. There is centraltranstentorial and subfalcine herniation.
$. Tonsillar herniation:
7n tonsillar herniation 'rare() a mass effect in the
posterior fossa causes the cerebellar tonsils to
herniate inferiorly through the foramen magnum
compressing the medulla and upper cervical spinal
cord. 3onscious patients complain of neck pain and
vomiting. They may have nystagmus) pupillarydilatation) bradycardia) hypertension and respiratory
depression. Early tonsillar herniation is difficult to
recogni;e in an unconscious patient. 7t may not be
evident on 3T scan since a!ial views cannot see the
pathology well. 7t is best seen on sagittal A7.
3linically changes in vital signs may be the only
clinical
clue in an unconscious patient.
=. #ubfalcine herniation 'cingulate herniation(: 6 unilateral supratentorial mass or hemorrhage
results in a midline shift. 7f the pressure pushing the
brain to one side is great enough) one of the
hemispheres is pushed under the fal! 'subfalcine(. This
may compress the anterior cerebral artery. There is
ipsilateral lateral ventricle compression and
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contralateral lateral ventricle dilation 'due to
obstruction
of the foramen of Aonroe(.
"iew subfalcine herniation.
The suprasellar cistern 'left image( is obliterated.
The 1uadrigeminal cistern is very compressed and
pushed posteriorly 'center image(. 6 subdural
hematoma with a midline shift is noted. There is central
transtentorial and subfalcine herniation.
5. #uperior vermian herniation: 6lso called ascending transtentorial herniation)
this
involves upward herniation of the vermis and cerebellar
hemispheres through the tentorial incisura due to a
mass effect in the posterior fossa. There is effacement
of the 1uadrigeminal cistern. There is hydrocephalus
due to compression of the a1ueduct of #ylvius.
eferences
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//0,-///+.
Girkwood H. ead Trauma. 7n: Girkwood H.
Essentials of @euroimaging) second edition. 3hurchill
ivingstone) @ew ork) /++5) pp. $$+-$5+.
Truwit 3) empert TE. igh esolution 6tlas of
3ranial @euroanatomy. 2illiams F 2ilkins) altimore)/++=.
2illing #H.