Convexity
Meningiomas
Majed Achtar
About C.Meningiomas
-Do not extend into the skull base dura or
dural sinuses.
-Often readily accessible.
-Difficulties often lie in deciding when to
operate and how to manage recurrent or
residual disease.
-Recurrent and residual disease managed also
by stereotactic radiosurgery and microsurgery.
Subclassification
According to location:
-Precoronal
-Paracentral
-Coronal
-Parietal
-Postcoronal
-Occipital
-Temporal
-Also pterional or lateral spheniodal wing
meningiomas.
-Grow solely or mainly outward toward
the frontal and temporal lobes.
-Subclassification used to recognizes the
eloquent (or noneloquent)
nature of the underlying cortex.
According to radiographic appearance :
-Globose
-En plaque
Diagnosis
-Mostly slowly growing, asymptomatic
-larger-than-expected
tumors at the time of diagnosis
-Symptomatic patients present most
commonly due to headache & seizure
in temporal ones.
-Other symptoms are site specific.
On T1-weighted magnetic resonance
-60% of meningiomas are Isointense, 30%
hypointense (compared to gray matter).
-Hyperintensity indicates a soft tumor
(edema/vascular flow).
-Hypointensity = fibrous/calcified.
-Edema requires treament and may
associate microcysts, anaplastic
angiomatous subtypes.
-Dural tail may represent tumoral
invasion.
MR Angiography
-Assesses the extent and pattern of
vascularity (e.g. vascular supply
from the contralateral middle
meningeal
Artery).
-The extent of tumor encroachment
on vascular structures.
-Feasibility of embolization.
LCCA injection – middle
meningeal supply to a right
convexity meningioma.
RECA injection(lateral, arterial
phase)
Deciding A Treatment
During observation:
-Growth rate may be linear.
-Erratic growth i.e. stable on serial imaging with a relatively
rapid growth.
-Higher grade tumors may be missed leading to operative
risks.
Treatment determined according to:
•Age/medical status.
•Tumor size.
•Symptom complex.
•Associated edema.
•Grade 0 resection in WHO I tumors with no recurrence.
•Radiosurgery for WHO II & III tumors.
Surgical Intervention
-Dexamethasone 2 weeks prior to surgery for
edema.
-Anticonvulsants (levetiracetam) prior or
loading dose during surgery for seizures.
-Patient placed parallel to floor for surgical
comfort and visualization.
-Planned incision for craniotomy.
-Harvesting of a pericranial graft for dural
closure.
Surgical position is adapted to
tumor location:
Supine for:
-Frontal plane, bicoronal incision behind the
hairline.
-Lateral sphenoidal wing/Frontotemporal,
pterional incision and temporalis dissection.
-Posterior temporal/lateral parietal, linear
incision.
Park Bench or straight prone:
-Medial parietal & Occipital lobe tumor, linear
incision.
Dural Dissection
-Done using a Penfield dissector.
-Bone flap lifted, not to tear the pial-capsule
connections between tumor and cortex.
-Bipolar coagulation, haemostatic agent or early
devascularization.
-May lead to copious bleeding at meningioma
base.
-Neuronavigation in case of clavarial invasion
and no pericranial graft is taken.
-Blurr holes are made, bone removed by drilling/
rongeur.
-Bone wax used for bleeding at edges.
Dural Incision
-Circumferential around tumor – 2 cm
margin from contrast component.
-May receive Meningial artery
branches.
-Early devascularization is crucial for
bloodless extracapsular dissection.
Debulking
-Partial removal done to minimize brain
retraction.
-Using Cavitron Ultrasonic Surgical
Aspirator in isointense tumors.
-For hypo & hyperintense tumors a
Garnet Laser, provides direct contact
and haemostasis.
-Up to a thin rim of the capsule.
Ultrasonic Aspirator Debulking Of A
Right Parietal Convexity Meningioma
Extracapsular Dissection
-Capsule dissection from pia done by surgical microscope.
-Tumor-pial adhesions are bipolared.
-Only tumor feeding arteries are sacrificed.
-Most vessels are en passant, cortical veins carefully dissected.
-Arachnoid dissected from tumor not brain.
-Cottonoid patties placed circumferentially to preserve
dissected structures.
-Excision of brain-invading tumors depends on cortical eloquency.
-Tumor reomval.
Extracapsular dissection
(Angular branch of MCA is
en passant).
Cottonoid patties (dotted
arrow), Vasculature
(arrow)
Dural Reconstruction
-After resection, the dura is
inspected for residual tumor.
-Closure with pericranial graft
(either harvested or artificial).
-Reinforced with fibrin glue.
-Titanium cranioplasty in case
of clavarial invasion.
Titanium cranioplasty
Postoperative Management
-1 night spent in the intensive care.
-Lab tests& imaging to rule out
haemorrhage/infarction.
-Seizure prophylaxis for 3 months followed
by EEG.
-Steroids slowly weaned for
edematous/symptomatic patients.
-Deep vein thrombosis prophylaxis (heparin).