Transcript Meningioamele parasagitale

Coordonator conf. dr. Ligia Tătăranu
stud. Lascăr Octavian-Toma
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tumors that fill the parasagittal angle, without
brain tissue between the tumor and the
superior sagittal sinus(SSS)
21 to 31% of intracranial meningiomas
tend to occur where arachnoid granulations are
denser
a higher incidence of malignant meningiomas
has been reported compared with
meningiomas in other locations
59% located in the right side
1. According to their location along the SSS:
-located in the anterior third(12,8%)-between crista
galli and the coronal suture
-located in the middle third(69,2%)-between
coronal suture and lambdoid suture
-located in the posterior third(17,9%)-between
lambdoid suture and the torcula
2. According to histopathological types:
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multiple sources of vascularization:
-meningeal arteries from extern carotid artery
-ethmoidal arteries from intern carotid artery
-cortical arteries
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related to the proximity of the lesion to the
Rolandic fissure
-sensory or motor seizures involving the
contralateral lower extremity
-contralateral hemiparesis
-parasthesias
papilledema- optic disc swelling that is
secondary to elevated intracranial pressure
(fundus eye exam is recommended)
-dementia
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tumors arising from either the anterior or
posterior third can remain undetected for long
periods until mass effect triggers noticeable
symptoms
-lesion in the anterior third-headache and
frontal lobe syndrome
-lesion in the posterior third-homonymous
hemianopsia
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CT-beneficial in cases in which either hyperostotic
or lytic calvarial changes are expected. Is also used
for prosthetic implants after surgery.
MRI-gives informations about the size, consistency
of the lesion and the relationship with the falx,
meninges, cortex, vascular structures
MRI+MRA(angiography)-gold standard. MRA is
used for the visualization of the arterial, venous
anatomy, collateral venous drainage patterns that
develop following sinus occlusion.
Preoperative consideration
1.Embolization-used as an adjuvant therapy to
reduce intraoperator blood loss and for
devascularization and subsequent necrosis of
the tumor.
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-used to guide surgical decision making and
preoperative planning based on six categories:
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in anterior third tumors, the patient is positioned
supine with the head slightly flexed
in middle third tumors, the patient is positioned
supine or lateral with the tumor positioned as the
highest point in the vertical plane
in posterior third tumors, the patient is positioned
semisitting, lateral, prone position with the tumor
bellow the horizontal plane
under the influence of the gravity, the ipsilateral
cerebral hemisphere is retracted , which facilitates
dissection, particularly in lesions with significant
falcine attachments
-in anterior third tumors is used a bicoronal skin
incision
-in middle third tumors is used a trapdoor or
horseshoe incision
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Direct visualization of the sinus wall during
dissection is the primary principle of the
craniotomy. Special attention is given to the
contralateral dura and adjacent veins, and
osteotomies over the SSS are performed last.
Elevation of the bone flap can be complicated
by engorged diploic anastomosis and by
frequently encountered invasion of the dura
and bone by the tumor.
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Dural opening: -made a semilunar dural flap
along the SSS under direct microscopic
visualization of the pial surface to avoid injury
to the cortical draining veins
the dural incision is made lateral from the
tumor
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Resection:
-dissection is initiated by visualization and
preservation of the tumor capsule on the lateral
margins
-if the tumor has reached the pial surface,
gentle dissection with selective bipolar
coagulation is used to separate the capsule
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all vascular structures must be identified and
followed to determine their contribution to the
tumor vasculature before coagulation because
pericallosal and callosomarginal branches are
frequently parasitized by these tumors and supply
the inferomedial aspect of the lesions
injury to critical venous structures ( rolandic veins)
can occur during dissection, and the surgeon must
be prepared for a venous reconstruction to avoid a
devastating venous hemorrhagic stroke in eloquent
cortex
in cases that require SSS wall reconstruction, an endto-end venous graft to the stump of the bridging
vein can be performed
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made with pericranial graft hervested during the
opening
fascia temporalis
dural substitute such as allogenic human skin
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postoperative hematoma
severe blood loss
carotid thromboses
pulmonary embolisms
surgical site infections
air embolism is influenced by the pacient
position
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can affect all histopathological grade tumors
tend to recur more frequently than
meningiomas at other locations
increased risk of recurrence for younger
patients
there is a relationship between extend of the
resection and recurrence rates