JC28 (Surgery) - Brain Tumors Flashcards
Primary brain tumours by cellular origin
Meninges - meningioma Neuroepithelial tissue - astrocytoma, glioblastoma Sellar - Pituitary adenoma Nerve sheath - Schwannoma, neurofibroma Neurons - gangliocytoma Ventricles: Ependymoma Embryonal - Medulloblastoma
Others: Lymphoma, germinoma, teratoma…etc
Metastatic tumor
Ddx brain tumors (diseases with similar clinical presentation)
Space occupying lesions:
- Tumor and Peri-tumoral edema
- Abscess, Tuberculoma
- Haematoma
Vascular
- Ischemic Stroke, infarct
- Hypoxic ischemic encephalopathy
- Hemorrhagic stroke
- SAH
- TBI, contusion
Hydrocephalus
Seizures (many types)
Misc:
- Sarcoidosis
- Cystic disease: arachnoid or parasitic
- Idiopathic Intracranial Hypertension
Routes of tumor metastasis to brain
Direct infiltration
Haematogenous
CSF
(Not lymphatics*)
Secondary metastasis to brain is most common in adults**
Common primary tumors and distribution between supratentorial and infratentorial fossa in adults
Supratentorial fossa = 85%
e.g.Secondary metastatic tumor ,Glioma ,Meningioma
Common primary tumors and distribution between supratentorial and infratentorial fossa in children
Medulloblastoma
Cerebellar astrocytoma
Ependymoma
Germ cell tumor
Infratentorial/ posterior fossa = 60%
Mass effects of brain tumor
Raised ICP symptoms, herniation
Focal neurological deficits: neuronal destruction, pressure effect, edema
Symptoms specific to site: e.g. acoustic neuroma - deafness and tinnitus, trigeminal schwannoma - Trigeminal nerve neuralgia …etc
Mechanisms of raised ICP due to brain tumor
Mass effect
Peritumoral edema
CSF outflow obstruction (non-communicating hydrocephalus)
Venous congestion (e.g. dural venous sinus congestion by meningiomas)
Explain why seizures are specific to supratentorial lesions
2 examples of structural epilepsy
Cerebellar cortex (infra-tentorial) is inhibitory in nature, unlikely for tumor to cause neuronal hyperactivity
Temporal lobe epilepsy from Mesial Temporal Sclerosis
Gelastic seizures from hypothalamic harmatoma
Symptoms and signs of brain tumours
Increased ICP and herniation: Generalized, dull, constant headache (worse in morning), vomiting, ↓consciousness
Papilloedema, Cushing’s triad (late features)
Seizures
Cognitive dysfunction and neurological deficits
Typical type of seizure associated with brain tumors
Repetitive and stereotyped seizures
4 modalities of imaging for clinically suspected brain tumor
CT brain +/- contrast
MRI with contrast ***
MR Spectroscopy (diff. high grade and low grade by chemical composition)
PET scan (systemic malignancy screen)
CT brain shows enhanced mass, list some ddx
Enhancement indicates
- Outside BBB, eg. meningioma (homogenously enhancing)
- Disruption of BBB, eg. high-grade tumours, stroke,inflammation
How to differentiate Low-grade vs high-grade brain tumors e.g. glioma
Differentiate with MR Spectroscopy
e.g. glioma
High-grade glioma: ↓T1W, heterogenous* enhancement with surrounding vasogenic edema* (↑T2W) ± central necrosis*
Low-grade glioma: ↑T2W, non-enhancing* expansile lesion with NO surrounding vasogenic oedema
Describe MRI appearance of primary intracranial lymphoma (/)
solitary/multifocal T2W-iso/hypointense,
contrast-enhancing lesions in subcortical regions,
classically a/w prominent diffusion restriction on DWI
Describe MRI appearance of metastatic brain tumor
Brain mets:
round, well-circumscribed, contrast-enhancing lesion** (variable signal on T1/2W images)
± surrounding oedema (if large),
involve multiple regions/ intracranial compartments**
Describe MRI appearance of meningioma
extra-axial, dura-based*
T1W-hypo/isointense, T2W-iso/hyperintense lesion
with strong homogenous* enhancement
2 modalities of imaging for surgical planning for brain tumor resection
Functional imaging: for pre-operative planning
□ Functional MRI (fMRI):
identify important cortical areas to guide surgical resection
□ MRI diffusion tension imaging (DTI, tractography):
identify important tracts to guide surgical resection
Medication therapies for brain tumors (relieving symptoms and peri-operative management)
Anticonvulsants: treatment/ Secondary prophylaxis of seizures, usually levetiracetam (Keppra)
High-dose glucocorticoids: reduction of cerebral oedema for palliation, or post-radiation therapy, usually dexamethasone
Tranexamic acid - perioperative reduction in bleeding
Modalities of treatment for brain tumours (5)
- Medical therapy
- Surgery
- Radiotherapy
- Chemotherapy
- Targeted therapy
5 surgical approaches for accessing brain tumors
→ Craniotomy: flap of bone cut and reflected
→ Burr hole: often for biopsy
→ Craniectomy: burr hole + removal of surrounding bone
→ Transphenoidal (pituitary)
→ Transoral (anterior tumours)
Surgical procedures for
- pathological diagnosis
- removal of tumor
- hydrocephalus
Stereotactic biopsy (usu. non-resectable tumors) or Burrhole bx for pathological diagnosis
Surgical resection for cytoredection and functional preservation
CSF shunting for hydrocephalus (VA/VP shunts) or EVD
5 intra-operative guidance techniques for surgical resection of brain tumors
- Frameless stereotaxy - localization of probe and structures with fMRI or tactography
- Real-time intraoperative MRI
- Evoked potential for electrophysiological monitoring (e.g. BAEP)
- Awake craniotomy with electrical stimulation of cortex
- 5-ALA guided resection (tumor cell glow under UV light)
General post-operative complications after brain tumor removal
→ Haemorrhage, brain swelling, hydrocephalus
→ Seizure, new neurological deficit
→ Infections
4 modalities of rehabilitation after brain surgery
physiotherapy, occupational therapy,
speech therapy, clinical psychology
3 types of radiotherapy for treatment of brain tumors
□ External beam radiotherapy (ERT):
standard radiotherapy with parallel rays
□ Interstitial brachytherapy: radioactive source
placed within brain (rarely used)
□ Stereotactic radiosurgery (SRS):
Multiple converging beams to focus on a selected
target
X-knife, Gamma knife, Cyberknife
Acute complications of cranial irradiation
Fatigue, loss of appetite (very common)
Headache: typically mild
Nausea/vomiting
Initial worsening of prior neurological S/S due to reactive swelling
Radiation dermatitis and alopecia
Acute encephalopathy (uncommon but severe)
Chronic complications of cranial irradiation
Radionecrosis: typically 1-3y after RT
Neurocognitive deficits
Vasculopathy and ischaemic stroke
Hypopituitarism*
Ocular toxicity: cataract, optic neuropathy, dry eye
Ototoxicity due to SN hearing loss
Most common origins of metastatic brain tumors
Distribution of intracranial sites for metastatic tumors
lung (16-20%), breast (5%), RCC (7-10%), colorectal (1-2%), melanoma (7%)
~80% cerebral hemisphere, ~15% cerebellum, ~5% brainstem
Commonest at watershed area between major arterial supplies and grey-white junction
Imaging features suggestive of metastatic brain cancer
multiple lesions, grey-white jx location, circumscribed margin, large volume of vasogenic oedema compared to size of lesion
Indications for surgical removal of brain tumor
→ Solitary operable lesion
→ Young pt with good function and reasonable life expectancy
→ Stable systemic disease with good treatment if secondary metastasis
4 histological types of localized astrocytoma (4) (/)
Pilocytic astrocytoma (I)
Subependymal giant cell astrocytoma (I)
Pleomorphic xanthoastrocytoma (II)
Anaplastic pleomorphic xanthoastrocytoma (III)
3 histological types of diffuse astrocytomas (/)
Diffuse astrocytoma (II) Anaplastic astrocytoma (III) Glioblastoma (IV)
Management options for astrocytoma/ glioma
- Watchful waiting for low-grade astrocytoma
First line:
- Surgical removal
- Temozolomide- based chemoradiation and external RT post-op
Second line:
- Anti-angiogenesis agent, eg. bevacizumab
- Tumor treating field (TTF): electrical field treatment
Glioblastoma multiforme
- tumor cell origin
- Growth pattern
- Prognosis
Undifferentiated glial cells or pre-existing astrocytomas
Infiltrative: into ventricular system and subarachnoid space
Poor prognosis: mean lifespan 14 months
Pituitary adenoma
- size cut-off
- Clinical presentation
macro- (>1cm) vs micro (<1cm)
Presentation:
- Visual: bitemporal hemianopia
- Hormonal hyper/hyposecretion (ACTH, GH, Prolactin)
- Cranial nerve palsy
- Bleeding (apoplexy)
- Hydrocephalus at 3rd ventricle
Management options for functional pituitary adenoma
□ Observation for non-secreting microadenoma
□ Dopamine agonist as 1st line for prolactinoma
□ Surgery Indications:
- Symptomatic/large non-secreting adenoma
- ACTH- or GH-secreting adenomas
- Second-line for prolactinoma (if refractory to medical Rx)
2 surgical approaches for pituitary adenoma resection
Approach:
- Transcranial (Craniotomy)
- Transphenoidal (transnasal or sublabial) via endoscopic/ microscopic
Management options for non-functional pituitary tumors
Watchful waiting for micro-incidentaloma, routine MRI
Hormone testing, visual field testing and routine MRI for macro-incidentaloma
Surgery or radiosurgery for symptomatic changes
Pituitary apoplexy
- Cause
- Presentation
- Imaging
- Management
Cause: haemorrhagic infarction of a tumour
Presentation: sudden or subacute (over 1-2d) onset of
→ Excruciating headache
→ Diplopia due to pressure on CN III
→ Hypopituitarism (esp adrenal crisis)
→ ± visual defects, vertigo and altered consciousness
Imaging: hyperdensity (acute blood) in pituitary region on CT
Mx: surgical decompression under steroid cover
Complications of transphenoidal surgery
Complications of transsphenoidal surgery:
- Endocrine: diabetes insipidus, hypopituitarism
- Vision loss
- CSF leakage and meningitis
- Vascular injury and CVA
- ENT symptoms
- Intracranial haemorrhage
Classical CT appearance of meningioma
→ Well-circumscribed dural-based lesion (with ‘dural tail’)
→ Homogenous enhancement
Symptoms and signs of acoustic neuroma (vestibular schwannoma)
→ Cochlear n. (95%): SN hearing loss, tinnitus
→ Vestibular nerve (61%): unsteadiness, mild vertigo
(typically NOT severe spinning vertigo due to gradual onset and compensation)
→ Trigeminal n. (17%): facial numbness, hyperesthesia, pain
(NO facial n. involvement)
Investigation and management of acoustic neuroma (vestibular schwannoma)
□ Ix: Pure tone audiometry (95% abnormal), MRI contrast (Cerebellar pontine angle tumour with enhancement)
□ Mx:
- surgery/ radiosurgery
- observation if old + small + limited hearing loss
