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FRCS Part 1 > Ch41 Meningeal, mesenchymal and melanocytic tumours > Flashcards

Ch41 Meningeal, mesenchymal and melanocytic tumours Flashcards

(49 cards)

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1
Q

Where do meningiomas arise from?

A

Arachnoid cap cells

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2
Q

What are the classical imaging findings associated with meningoimas?

A

Dural tail Enhancement Hyperostosis Arachnoid cleft T1 Iso and T2 hyo-intense Frequently calcify

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3
Q

What are the surgical indications for resection of a meningioma?

A

Documented growth on serial imaging Symptoms not controlled by medical therapy (seizures / mass effect) T2 signal in the brain

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4
Q

What are the classical histological features of a meningioma?

A

Psammoa bodies Keratinous whorls Spindle-shaped cells

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5
Q

What % of intracranial tumours are meningiomas?

A

36%

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6
Q

What is a rapidly growing tumour that mimics a meningioma?

A

Haemangiopericytoma

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7
Q

What are the layers of the dura and arachnoid?

A

Dura - periosteal > meningeal > border Arachoid - barrier > trabecular Pia Basement membrane Brain

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8
Q

What condition is associated with multiple meningiomas?

A

NF-2 (called meningiomatosis) and NF-1

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9
Q

What is an en plaque meningioma?

A

A diffuse sheet of tumour

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10
Q

What are the risk factors for meningiomas?

A

Ionising radiation and NF

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11
Q

What sex has a higher incidence of meningiomas?

A

Females (2:1)

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12
Q

Where % of childhood meningiomas are intraventricular?

A

28%

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13
Q

What is the most common location for adult meningiomas?

A

Parasagittal (20%) > Convexity (15%) > Tuberculum sella (13%) > Sphenoid ridge (12%) and olfactory groove (10%)

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14
Q

Where do sphenoid wing meningiomas arise?

A

Lateral, middle 1/3 (alar) and medial (clinoidal)

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15
Q

How are parasagittal / falcine meningiomas grouped?

A

Anterior = ethmoid plate to coronal suture (45%) present with H/A and mental status change Middle = coronal suture to lambdoid suture (35%) present with jacksonian seizure or progressive monoplegia Posterior = Lambdoid suture to torcula (25%) present with H/A, visual symptoms or focal seizures

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16
Q

What is the classification system for sinus involvement by meningiomas?

A

Sindou (2006) classification 1 - attached to lateral wall 2 - invasion into lateral recess 3 - invasion of the lateral wall 4 - invasion of lateral wall and roof 5 - total sinus occlusion but contralateral wall spared 6 - total sinus occlusion with invasion of all walls

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17
Q

What is the earliest weakness that occurs with parasagittal meningiomas compressing the paracentral lobule?

A

Foot drop (as these compress the ankle area)

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18
Q

What is Foster-Kennedy syndrome?

A

Anosmia, unilateral optic atrophy and contralateral papilloedema

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19
Q

How do olfactory groove meningiomas present?

A

Foster-kennedy syndrome Apathy / abulia Urinary incontinence Optic nerve / chiasm compression causing VFD Seizures

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20
Q

What is the blood supply to olfactory groove meningiomas?

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A

Anterior and posterior ethmoidal arteries arising from the opthalmic artery (not embolized due to risk of blindness). Some middle meningeal feeders may be present

21
Q

Where do planum sphenoidale meningiomas arise from?

Study These Flashcards
A

Anterior to the limbus of the sphenoid bone

22
Q

What lies immediately posterior and inferior to the limbus sphenoidale?

Study These Flashcards
A

The prechiasmatic sulcus

23
Q

What part of the sphenoid bone is in continuity with the prechiasmatic sulcus posteriorly?

Study These Flashcards
A

The Tuberculum sella

24
Q

What is the limbus of the sphenoid continuous with laterally?

Study These Flashcards
A

The falciform ligament running on the roof of the optic canal

25
What dural structure lies beneath the opthalmic artery?
The distal dural ring
26
What are the branches of the superior hypophyseal artery?
1 Optic, 2 Infundibular and 3 Diaphragmatic branches
27
Where do olfactory groove meningiomas arise from?
The cribiform plate and crista gali
28
What happens to the optic nerve with olfactory groove and tuberculum sella meningiomas?
Olfactory groove meningiomas push the optic nerve downwards whlst tuberculum meningiomas list the optic nerve
29
What is the demarcation of the anterior and middle fossas in the midline?
The limbus sphenoidale!
30
What is chiasmatic syndrome?
Primary optic atrophy + bitemporal hemianopsia
31
Where do foramen magnum meningiomas arise?
In the french cooperatives study of 106 FM meningiomas, 31% from anterior, 56% lateral and 13% from posterior lip.
32
What factor affect the rate of recurrence of a meningioma?
The WHO grade, histological subtype, proliferation index (Ki67) and the presence of brain invasion.
33
What is the most common histological subtype of meningioma?
Meningothelial aka syncytial - sheet of polygonal cells
34
What are the different WHO class 1 meningiomas?
Meningothelial - most common Fibroblastics - more rubbery Transitional - between meningothelial and fibroblastic Psammomatous - Calcified meningothelial networks Angiomatous Microcystic - cysts which may coalesce Secretory - cause lots of oedema Lymphoplasmacytic Metaplastic
35
What makes a meningioma atypical and anaplastic?
WHO 2 Atypical = 5-20 mitotic figures per 10 hpf or brain invasion. Includes chordoid and clear cell subtypes WHO 3 Anaplastic = \>20 mitotic figures per 10 hpf. Includes papillary and rhabdoid subtypes
36
What are the malignant meningiomas (WHO grade 3)?
Anaplastic, papillary and rhabdoid
37
What are the recurrence rates of different WHO grade meningiomas?
WHO 1 = Ki67 index 1% = 9% recurrence WHO 2 = Ki67 index 2% = 29% recurrence WHO 3 = Ki67 index 10% = 50% recurrence
38
What is the differential diagnosis of a meningioma?
1. Dural met 2. PXA - peripherally located and may have a dural tail 3. Gliosarcomas 4. Inflammatory conditions such as Rosai-Dorfman, Erdheim-chester and IgG-4 related hypertrophic pachymeningitis
39
What are the most common primary intracranial tumour?
Meningiomas
40
What is the blood supply to suprasellar meningiomas (tuberculum meningiomas)?
Ophthalmic artery feeders
41
What artery feeds petroclival meningiomas?
Artery of Bernasconi and Cassinari
42
How do you position the head for parasagittal meningiomas?
Anterior 1/3 - supine with neck flexed and deck-chair position Middle 1/3 - lateral position with head turned 45 degrees so tumour side is up or down (facilitates the brain falling away) Posterior 1/3 -prone position
43
How do you approach a parasagittal meningioma where the sinus is occluded?
If completely occluded then can be resected but watch out for collaterals If partially occluded and anterior then take it, otherwise leave the part of the meningioma in the sinus and give post-op SRS
44
What are the 4Ds of meningoma surgery?
As described by Al-mefty include: Dedress, Devascularise, Debulk and Dissect
45
How would you perform a resection of a medial sphenoid wing meningioma?
Lumbar drain, Head turned 30 degrees, Extradural sphenoid wing drilling, sylvian fissure split. Identify ACAs by following the MCA and ICA. Identify optic nerve at the optic canal. Leave any component within the cavernous sinus.
46
How do you approach olfactory groove meningiomas?
Bifrontal if large or pterional for small lesions. For bifrontal the SSS is divided. Devascularise the base of the tumour early. Debulk the lesion and then dissect the boundary taking care to protect the ACA and optic nerves. Cranialise the frontal sinus and use a pericranial flap to repair the defect.
47
How do tuberculum sellae meningiomas displace the optic nerves?
Posteriorly and laterally
48
How do you approach a lateral or anterior FM meningioma?
Far lateral or Transcondylar approach
49
How do you perform a far lateral approach?
Hockey shape incision from midline to TS and down to mastoid bone Muscle dissection flapped down Unilateral suboccipital craniectomy to the condyleand C1 laminectomy.

FRCS Part 1 (85 decks)

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