1. Convexity Meningiomas Majed Achtar

2. 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.

4. Subclassification -Precoronal -Coronal -Postcoronal -Paracentral -Parietal -Occipital -Temporal According to location:

5. -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

6. 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.

7. 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.

9. 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.

10. LCCA injection – middle meningeal supply to a right convexity meningioma. RECA injection(lateral, arterial phase)

11. 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.

12. 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.

13. 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.

16. 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.

18. Dural Incision -Circumferential around tumor – 2 cm margin from contrast component. -May receive Meningial artery branches. -Early devascularization is crucial for bloodless extracapsular dissection.

20. 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.

21. Ultrasonic Aspirator Debulking Of A Right Parietal Convexity Meningioma

22. 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.

23. Extracapsular dissection (Angular branch of MCA is en passant). Cottonoid patties (dotted arrow), Vasculature (arrow)

24. 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.

25. Titanium cranioplasty

26. 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).