Surgical Management of Parasagittal and Convexity Meningiomas
Schmidek & Sweet Operative Neurosurgical techniques Chapter 32
1/12/58
Title
– There is today nothing in the whole realm of surgery more gratifying than the successful removal of a meningioma with subsequent perfect functional recovery
– Harvey Cushing
Epidemiology and Significance
• The most common primary brain and central nervous system tumor
• 6.29 per 100,000 persons• 34% of all primary brain tumors• Incidence rate increases with older age and peaks in
persons over 85 years of age
Epidemiology and Significance
• Meningiomas occur most frequently on the – convexity (19% - 34%)– parasagittal locations (18% - 25%)– sphenoid wing and middle cranial fossa (17% - 25%), – anterior skull base (10%)– posterior fossa (9% - 15%)– cerebellar convexity (5%)– clivus (<1%)
Location
convexity parasagittal sphenoid wing 25anterior skull base 10 posterior fossa 15 etc
Etiology
• Sporadic– Hormonal : progesterone influence in the development
of meningiomas
• Radiation Induced– Two large cohort study– Higher pathologic grade and more aggressive behavior– Increased incidence of multiple tumors
Etiology
• Neurofibromatosis type 2 (NF2)• Autosomal dominant• Central and peripheral nervous system tumors
(meningiomas, schwannomas, ependymomas)• Ophthalmologic findings (cataracts, epiretinal
membranes, retinal hamartomas)• Cutaneous findings (skin plaques, subcutaneous tumors)
Classification : Convexity Meningioma
• Refer to tumors of the supratentorial space that have their sole attachment to the dura covering the convexity of the cerebral hemispheres
• Location : temporal, frontal, paracentral, parietal and occipital
Classification : Parasagittal Meningioma
• Refer to attachment to the dura forming the outer layer of the SSS and occupy the parasagittal angle displacing brain from this location
• Location : anterior, middle, posterior
Classification
Clinical Presentation
• Convexity meningioma– Incidental finding– Raise intracranial pressure– Headache, seizures ,hemiparesis
• Parasagittal Meningioma – Anterior third : headache, personality changes– Middle third : Jacksonian seizures, headache and
progressive hemiparesis– Posterior third : headache, seizures and gradual
hemianopsia
Indication for surgery : Incidental Meningioma
• FU MRI 3 Mo after initial diagnosis – No growth or slow linear growth• monitor tumor 3-6 Mo
– Exponential growth• specific imaging
• For each clinical situation, the decision to recommend surgery should be evaluated on an individual basis, incorporating patient comorbidities, age, observed growth rate, and image-based predictive factors for growth
Indication for surgery
• Convexity Meningioma– development of neurologic symptoms– significant peritumoral edema– adjacent to important neurovascular structures (Sylvian
veins, middle cerebral arteries, superficial anastomosing veins) and eloquent cortices
• Parasagittal Meningioma• Same to convexity meningioma• extent of SSS involvement
Preoperative evaluation
• Superior sagittal sinus involvement– contrast-enhanced MR-venography (CE-MRV)– If SSS obstruction : significantly dilated scalp veins and
diploic veins in addition to engorged cortical venous collaterals
• Bony changes– Bone removal and cranioplasty– CT : hyperostosis changes or direct bone invasion
• Tumor and brain characteristics– MRI : gold standard – T2 : arachnoid clef for anatomical plane
Surgical Treatment : General
• Preoperative care– Antiepileptic medications from venous hypertension and
brain swelling– Preoperative steroids, started 4 to 7 days before surgery
to allow reduce peritumoral vasogenic edema and swelling
– Proton pump inhibitors for GI ulcer prophylaxis– Intermittent pneumatic compression device– preoperative antibiotics
• Embolization– Not necessary for convexity or parasagittal meningiomas
of any size
Simpson grading
Surgical Treatment : Parasagittal Meningioma
• Position– Anterior third : supine position with the head and neck
in a neutral or gently flexed position– Middle third : supine semisitting position– Posterior third : prone position
• Incision– Frameless stereotaxic navigation use– Anterior third : bicoronal incision– Middle and posterior third : bicoronal incision or U
shape(at least 2 cm past the midline to provide exposure to the uninvolved side of the SSS)
Surgical Treatment : Parasagittal Meningioma
• Exposure– Harvest free pericranial graft– Craniotomy should be at least 1.5 to 2 cm away from the
junction of the tumor mass and the dural tail– Bipolar cautery for bleeding edge of tumor, dural tear– Gelfoam for bleeding of arachnoid granulations, venous
lakes, or the area around
Surgical Treatment : Parasagittal Meningioma
• Resection– C-shaped dural opening, with its base towards the SSS– Initial separation of the tumor from the underlying
cortex along arachnoid planes proceeds– Perform central debulking of the tumor to avoid avulsion
or disruption of venous elements
Surgical Treatment : Parasagittal Meningioma
• SSS involvement– Type I : peel from attachment and cauterized– Type II : left the residual tumor in SSS– Type III : allow for ligation and resection of SSS
Surgical Treatment : Parasagittal Meningioma
• Closure– Pericranium for shrinkage dura, defect dura– Tack-up suture– Cranioplasty for craniectomy
Surgical Treatment : Convexity Meningioma
• Positioning– Head placed above the level of the heart : park bench or
prone position– Place tumor at the highest point of the operative field
Surgical Treatment : Convexity Meningioma
• Exposure– Small tumor : linear incision– Larger tumors and those of the parietoccipital : U-
shaped incisions– Frontal tumor : three quarters bicoronal incision or a
pterional incision– Harvest pericranium graft– Burr hole up to age of patients– Bleeding from tumor stop with bipolar– Bleeding from arachnoid granulation and venous lake
stop with application of woven oxidized cellulose polymer and Gelfoam
Surgical Treatment : Convexity Meningioma
• Resection– Goal is Simpsom gr. I resection– Incision at least 1 cm remote to the tumor mass– Cottonoid patties are placed into the arachnoid cleft
between tumor and brain to maintain dissected plane– Large tumors are centrally debulked.
• Closure– Pericranium for shrinkage dura, defect dura– Tack-up suture– Cranioplasty for craniectomy
Postoperative Care and Complications
• Neurologic status after patients are awoken from anesthesia
• Observe neuro sign• Head elevated 30• Perioperative antibiotic prophylaxis is
discontinued within 24 hours of surgery• DVT prophylaxis : low-dose, unfractionated
subcutaneous heparin or low-molecular-weight heparin + intermittent pneumatic compressive until patient discharge
Postoperative Care and Complications
• Parasagittal tumors any disruption of collateral veins warrants extended monitoring for the development of delayed sequelae (2 to 4 days after resection) : venous infarction and seizures
• Can be evaluated for occult complications with either CT or MRI imaging• Dressings are removed on the second day after
surgery
Outcomes and Follow-Up
• The extent of surgical resection is the most important factor in the prevention of recurrence
• The 5-year recurrence rate– Convexity meningioma : 0-3 %– Parasagittal meningiomas : 2-18%
• WHO histopathologic grading is the major predictive factor of recurrence– Benign tumors (WHO grade I) : 7-25%– Atypical meningiomas (WHO grade II) : 29-52%– Anaplastic meningiomas (WHO grade III) : 50-94%