meningiomas

Introduction

tumours arising from arachnoidal cap cells in the meninges
usually slow growing
92% are benign (“Grade I”), although may recur after surgery but still have benign histology
- although usually benign a “petro-clival” meningioma being deep within the skull base near the brainstem is typically fatal without treatment due to its location and Rx can be challenging, often with poor outcomes
are usually well-circumscribed, and takes on the form of the space it occupies

accounts for 30% of adult brain tumours and affects ~1 in 1000 adults
women 2x men (although malignant ones are more likely in men)
becoming more likely with age, most are found in those over age 50yrs
25% are in falx cerebri, 19% are in the convexity of the brain, 17% are on the sphenoid ridge, 9% are suprasellar, 8% are in post fossa, 8% are in olfactory groove
~7% are atypical meningiomas (“Grade II”) with mean survival of ~12 yrs
2% are malignant anaplastic meningioma (“Grade III”) which are aggressive with mean survival of ~3 yrs

most are sporadic rather than familial
FH meningioma
neurofibromatosis type 2 - 50% develop one or more meningiomas
ionizing radiation - frequent dental xrays (esp. older higher dose ones);
long-acting injectable contraception depot medroxyprogesterone acetate (Depo-Provera)
- class action against manufacturer Pfizer on claims it may increase the risk of meningiomas - studies suggest it's use increases risk of meningioma by 1.5-5.5 fold, and risk appears to be greatest in those starting over age 31 yr or using it for more than 4 years ¹⁾
high doses of cyproterone acetate

most are asymptomatic, esp. if < 2cm
symptoms depend on the location and occur as a result of the tumor pressing on nearby tissue
- may cause focal seizures

select asymptomatic cases can be Mx by watchful waiting and repeat scanning as over half have no growth on repeat scans and only 6% develop symptoms
younger adults are more likely to have growth and should be considered for neurosurgical referral
can usually be surgically resected if location is amenable to surgery but 6-9% have ongoing symptoms from either the tumour or the surgery
if invasion of the adjacent bone occurs, total removal is nearly impossible
transarterial embolization has become a standard procedure in preoperative management of meningiomas
10yr recurrence rates after surgery are quite high (based on Simpson grading of resection: 40% with subtotal resection, 29% with complete resection but no dura resected, 19% with dura resected as well)

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