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Brain Tumours

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Overview

As with all tumours, brain tumours can be classed as benign or malignant, but technically speaking, benign brain tumours cannot truly be defined as so, due to their growth and mass effect on surrounding structures. As a result, brain tumours are usually classified as follows:

  • High-grade tumours: grow rapidly and are aggressive
  • Low-grade tumours: grow slowly and unlikely to invade surrounding tissue

Epidemiology

  • In adults, most brain tumours are supratentorial
  • In children, most brain tumours are infratentorial
  • Secondary metastases are the most common form of brain tumour
  • Primary CNS lymphomas are more common in patients with AIDS

Risk Factors

  • Ionising radiation
  • Immunosuppression – increases risk of primary CNS lymphoma
  • Neurofibromatosis I or II
  • Tuberous sclerosis
  • Other inherited syndromes e.g. von Hippel-Lindau syndrome

High-Grade Tumours

Glioblastoma multiforme

  • Most common in adults
  • Associated with poor prognosis
  • Imaging: solid tumour with ring enhancement if contrast used
  • Treatment: surgery with post-op chemotherapy/radiotherapy
  • Dexamethasone is given for oedema

Low-Grade Tumours

Meningioma

  • Second most common in adults:
  • Usually arise from the dura mater
  • Imaging: MRI shows well-defined lesions of dural origin
    • There may be surrounding oedema
  • Histology: psammoma bodies may be seen
  • Treatment: watch and wait, radiotherapy, or surgery

Pituitary adenoma

  • Can be secretory (produce hormone in excess) or non-secretory
  • Can be microadenoma (<1cm) or macroadenoma (>1cm)
  • May present with symptoms of excess hormone e.g. Cushing’s disease
  • May have bitemporal hemianopia due to tumour pressing on optic chiasm
  • Imaging: MRI shows tumour
  • Treatment: transsphenoidal surgery/medication depending on cause

Craniopharyngioma

  • Tumours that arise from remnants of craniopharyngeal duct and/or Rathke’s cleft
  • Imaging: MRI shows tumour
  • Histology: can be adamantinomatous (in children) or papillary (in adults)
  • Treatment: surgery with or without post-op radiotherapy

Vestibular schwannoma (acoustic neuroma)

  • Tumours of CN VIII arising from Schwann cells of nerve sheath
  • Neurofibromatosis type II is associated with bilateral vestibular schwannomas
  • Imaging: MRI shows tumour in cerebellopontine angle
  • Treatment: watch and wait, radiotherapy, or surgery

Astrocytoma

  • Can also be high-grade

Secondary Metastases

Common metastases spreading to the brain are:

Management

  • Management varies depending on investigations and the tumour type
  • Generally, if cerebral oedema is present, dexamethasone is given to reduce its effects on intracranial pressure
  • Surgery is generally given to patients with those with fewer metastases provided the primary is effectively controlled
  • For those who are unsuitable for surgery, whole-brain radiotherapy is offered

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