CNS Tumours

Question 1

Via what path do brain tumours like to spread?

Answer 1

White matter tracts

Question 2

Define neurotropic

Answer 2

Predilection for invading brain tissue but not rest of the body (doesn’t metastasise)

Question 3

Pros and cons of CT scans

Answer 3

ADV: Very quick (emergencies), low dose, good to see bone

DISADV: Hard to identify fine structures withing the brain

Question 4

Pros and cons of MRI

Answer 4

ADV: good to view finer structures withinthe brain (can see oedema etc), can be enhanced w/ contrast e.g. view perfusion

DISADV: takes longer(30-60mins)

Question 5

Neurosurgical treatment of tumours (3 e.gs)

Answer 5

• Stereotactic biopsy: inoperable tumours (about 0.5cm tissue)
  
  • Open biopsy: inoperable but approachable tumours
  • Craniotomy for debulking (as much tissue as possible)

Question 6

How to classify CNS tumours (4)

Answer 6

Intra-axial: located inside CNS (e.g. glioma, neuroblastoma)
Extra-axial: located outside CNS (e.g. meningioma)

Primary: arise from CNS
Secondary: from another organ (metastasis)

Cells of origin (WHO)

Grades- prognostic value

Question 7

Explain grading system in CNS tumours

Answer 7

Grade I: Long term survival/cured
Grade II: Cause death in more than 5 years
Grade III: Cause death within 5 years
Grade IV: Cause death within 6 months-1 year

(No staging in CNS tumours except medulloblastoma)

Question 8

Most common primary tumour of the brain?

Answer 8

Glioma

Question 9

Grade I Astrocytoma: types and prognosis

Answer 9

Grade I —> surgical resection —> pt is cured
• Pilocytic Astrocytoma: typically remain where they start and do not spread, “most benign” of astrocytomas; 2 other less well known grade I’s include cerebellar astrocytoma and desmoplastic infantile astrocytoma

Associated w/ hydrocephalus, under microscope: “hair-like” (pilocytic) cells

Question 10

Grade II Astrocytoma: types and prognosis

Answer 10

Grade II —> complete resection —> pt is close to being cured as possible (>5 yrs survival)
• Diffuse Astrocytoma (aka Low-Grade/ AstrocytomaGrade II): Types include fibrillary, gemistocytic, protoplasmic astrocytom- Grade II astrocytomas tend to invade surrounding tissue and grow at a slow pace
Subependymal Giant Cell Astrocytoma: ventricular tumours associated w/ tuberous sclerosis

Question 11

Grade III Astrocytoma: types and prognosis

Answer 11

Grade III —> resection + chemotherapy + radiotherapy —> <5 years
• Anaplastic Astrocytoma: requires more aggressive treatment than beign pilocytic astrocytoma

Question 12

Grade IV Astrocytoma: types and prognosis

Answer 12

Grade IV —> without treatment —> couple of months
—> with treatment —> 1.5 years
• Glioblastoma Multiform/ Glioblastoma/ GBM: 2 types: primary (de novo) and secondary. Primary tumours are very aggressive and most common form of grade IV astrocytoma. Secondary tumours originate as lower grade tumours and evolve into a grade IV tumour

Seizures, focal neurological deficit