Coordonator conf. dr. Ligia T ă t ă ranu stud. Lasc ă r Octavian-Toma

 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:

 multiple sources of vascularization:  -meningeal arteries from extern carotid artery  -ethmoidal arteries from intern carotid artery  -cortical arteries

 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

 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

 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.

-used to guide surgical decision making and preoperative planning based on six categories:

 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

 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.

 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

 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

 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 end- to-end venous graft to the stump of the bridging vein can be performed

 made with pericranial graft hervested during the opening  fascia temporalis  dural substitute such as allogenic human skin

 postoperative hematoma  severe blood loss  carotid thromboses  pulmonary embolisms  surgical site infections  air embolism is influenced by the pacient position

 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