JC28 (Surgery) - Brain Tumors Flashcards by Max Kam

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

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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

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Routes of tumor metastasis to brain

Direct infiltration
Haematogenous
CSF

(Not lymphatics*)

Secondary metastasis to brain is most common in adults**

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Common primary tumors and distribution between supratentorial and infratentorial fossa in adults

Supratentorial fossa = 85%
e.g.Secondary metastatic tumor ,Glioma ,Meningioma

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Common primary tumors and distribution between supratentorial and infratentorial fossa in children

Medulloblastoma
Cerebellar astrocytoma
Ependymoma
Germ cell tumor

Infratentorial/ posterior fossa = 60%

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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

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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)

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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

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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

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Typical type of seizure associated with brain tumors

Repetitive and stereotyped seizures

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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)

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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

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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

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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

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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**

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Describe MRI appearance of meningioma

extra-axial, dura-based*
T1W-hypo/isointense, T2W-iso/hyperintense lesion
with strong homogenous* enhancement

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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

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Medication therapies for brain tumors (relieving symptoms and peri-operative management)

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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)

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Medical therapy
Surgery
Radiotherapy
Chemotherapy
Targeted therapy

5 surgical approaches for accessing brain tumors

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→ 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

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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

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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

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→ Haemorrhage, brain swelling, hydrocephalus
→ Seizure, new neurological deficit
→ Infections

4 modalities of rehabilitation after brain surgery

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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

JC28 (Surgery) - Brain Tumors Flashcards

(43 cards)