Brain metastases

Question 1

Definition

Answer 1

When cancer cells spread from their primary location to the brain, through haematogenous spread

Question 2

Preventative messures of the body from mets

Answer 2

Blood-brain barrier
- but once crossed, cancer cells can proliferate and form a single (or multiple) tumour(s), causing local destruction and oedema = raised ICP and subsequent associated Sx

Question 3

What is the tentorium cerebelli?

Answer 3

An extension of the dura mater that invaginates to separate the occipital and temporal lobes (superiorly) from the cerebellum and brain stem (inferiorly)

Question 4

How are brain mets catogorised

Answer 4

• Supratentorial: 80% in adults
• Infratentorial: 20%
  (15% in cerebellum; 5% in brainstem).

Question 5

Signs

Answer 5

Focal neurological signs:
- Determined by site of brain mets
Signs of raised ICP: papilloedema on fundoscopy
Cushings triad: seen in impending brain herniation
- HTN,
- bradycardia,
- irregular respirations
Hemiparesis
Cranial nerve palsies: abducens nerve palsy (CNVI) is MC due to its long intracranial course

Question 6

Symptoms

Answer 6

• HA: worsened when lying flat e.g. at night and early morning
• N+V
• Reduced consciousness
• Seizure
• Blurred vision

Question 7

Diagnosis

Answer 7

GOLD STANDARD: MRI
- Can detect small mets
- CT often used due to its availability and useful in emergancies
Consider:
- PET scan to identify primary cancer site

Question 8

Treatment

Answer 8

Acute setting: Corticosteroids = dexamethasone used to reduce vasogenic oedema, can rapidly improve Sx
Whole brain radiotherapy: used for multiple mets
Sterotactic radiosurgery: delivery of high dose radiation
Surgery: curative option considered for solitary mets causing sig mass effect and for dx purposes when primary is unknown
Chemo: drugs with good CNS penetration,
- temozolomide,
- topotecan,
- irinotecan
Targeted therapies: dependant on type of primary cancer + Px overall health
- checkpoint inhibitor (ICI),
- ipilimumab may have some activity in recurrent brain metastase
-

Question 9

Complications

Answer 9

• Raised ICP
• Neurological deficits
  = hemiparesis
  = aphasia
  = visual field deficits
  Seizures
  Neuocognitive deficits