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%