Neurosurgery JC028: A Mass In The Brain: Brain Tumours Flashcards
Classification of Brain tumours
Primary
- Benign (e.g. Meningioma, Pituitary adenoma)
- Malignant (e.g. Glioblastoma)
- “Intermediate”
—> not always clear cut
—> histologically benign
—> tendency to recur / dedifferentiate into malignant lesions
—> e.g. some “low-grade” gliomas, craniopharyngioma
Secondary (Metastasis)
- ***commonest lesions in adults
- increasing frequency (∵ effective systemic therapy for extracranial malignancy —> “chronic disease”)
- lung, breast, colon, ***melanoma (highest propensity)
Primary brain tumour by cellular origin
Important:
- Meninges: ***Meningioma
- Neuroepithelial tissue: **Astrocytoma, **Glioblastoma (GBM), ***Ependymoma
- Sellar: ***Pituitary adenoma
- Nerve sheath: Schwannoma, Neurofibroma
Others:
- Neuronal: Gangliocytoma
- Embryonal: ***Medulloblastoma
- Lymphoid cells: Lymphoma (esp. in immunocompromised patients e.g. HIV +ve)
- Germ cells: Germinoma, Teratoma
- Malformative tumour: ***Craniopharyngioma
Age, Location, Histology of brain tumours
Adults: - Supratentorial (e.g. Cerebrum) —> ***Metastasis —> Glioma —> ***Meningioma
Children: - Infratentorial (Cerebellum, Brainstem) —> ***Medulloblastoma —> Cerebellar astrocytoma —> ***Ependymoma —> Germ cell tumour
***Clinical presentation of brain tumour
1. ↑ ICP Causes: - ***Mass effect - Peri-tumoural edema - ***CSF flow obstruction —> Non-communicating hydrocephalus - ***Venous congestion (by Meningioma)
Effect:
- Brain herniation (Subfalcine, Central, Uncal, Tonsillar) —> Brainstem compression
2. Focal neurological deficits Loss of function due to: - Neuronal destruction - Pressure effect - Edema (reversible with steroids)
- **Enables clinical localisation:
- e.g. Aphasia (Broca’s area)
- RLL weakness (Left motor cortex)
- Truncal ataxia (Vermis cerebellum)
- Dysmetria, Dysdiadochokinesia (Cerebellar hemisphere)
- Cognitive decline / Personality change (Frontal lobe)
- Seizure
- unknown mechanism
- **Neuronal hyperactivity (uncontrolled cerebral discharges)
- **ONLY Supratentorial tumours (NOT in Infratentorial lesions, ∵ Cerebellum functionally is inhibitory)
- Partial / Grand-mal (generalised tonic-clonic) seizure
- Complex partial seizure
- Mesial Temporal Sclerosis (affecting hippocampus) —> Temporal lobe epilepsy (TLE)
- Hypothalamic harmatoma (malformation condition in children) —> Gelastic seizure - Others specific to location
- Acoustic neuroma (deafness, tinnitus)
- Acoustic neuroma (hemifacial spasm)
- Trigeminal schwannoma (CN5 neuralgia)
- Pituitary adenoma (bitemporal hemianopia, hyper/hyposecretion of pituitary gland)
- Craniopharyngioma (failure to thrive, precocious puberty)
Diagnosis of brain tumour
-
**Contrast enhancement imaging
- Contrast can leak into lesion via blood supply if BBB destroyed
- Meningioma: **intense **dura-based **homogenous enhancement (homogenous ∵ supplied by ECA —> no BBB)
- Low-grade glioma: heterogenous weaker enhancement (∵ BBB not disrupted)
- Malignant glioma: enhancement of lesion (∵ vascular + leaky BBB)
(MR spectroscopy can also differentiate low grade / high grade via chemical composition: High choline = High cell turnover) - PET
- malignant lesion: tend to be Hypermetabolic -
**Functional MRI + **Diffusion Tensor Imaging (DTI) Tractography
- based on metabolic activity / bloodflow
- DTI: allow visualisation of tracts
- Locate functionally important structures —> Aids surgical planning
Tumour haemorrhage
Tumour tends to be vascular
- Bleeding Glioblastoma
- mimic Haemorrhagic stroke (can only differentiate on MRI) - Pituitary Apoplexy
- **acute visual loss
- **hormonal crisis
- ***SAH - Sellar tumour
- mimic Cerebral aneurysm
Principles and Options of treatment
Principles:
- Aim at cure if feasible
- Preserve life
- Preserve function
- Preserve personhood
- Maximise QOL
- Do not treat scan
Treatment options:
- General medication
- Surgical biopsy + resection
- Radiotherapy
- Chemotherapy
- Targeted therapy
- Immunotherapy
Medication therapy
- Anticonvulsant (e.g. Phenytoin, Levetiracetam)
- prophylaxis / treatment (if already seizure)
- ***NOT for Infratentorial lesion - Steroids (e.g. Dexamethasone)
- exclude infection first
- ↓ cerebral edema + relieve symptoms
- peri-operative use / palliation
- S/E: DM, immunosuppression, peptic ulcer - Tranexamic acid
- inhibitor of plasminogen activation
- peri-operative to ↓ bleeding
Principles of Brain tumour surgery
- Obtain histological diagnosis
- Maximal safe removal
- preserve life
- preserve function - ***“Resection margin” difficult
Main questions:
- Whether to resect
- When to resect
- How to resect
- How much to resect
Surgery techniques
- ***Craniotomy
- ***Neuronavigation + Microsurgery
- Awake craniotomy for ***Speech cortex mapping
- electrical stimulation over speech cortex —> induces speech arrest —> allow mapping of speech cortex (∵ varies between people) - ***Intraoperative MRI
- confirm total removal
- identify residual tumour
Monitoring:
- **Electrophysiological monitoring —> alert surgeons of iatrogenic surgery
- Somatosensory evoked potential (SSEP)
- Motor evoked potential (MEP)
- Brainstem auditory evoked potential (BAEP)
- Motor mapping
Radiation therapy for brain tumour
Types:
- Whole brain
- Traditional
- ***Stereotactic radiosurgery
- Aim to deliver high treatment dose to tumour bed
- Minimise radiation to normal tissue
- Balance between treatment efficacy and SE
- can treat both Benign + Malignant lesions
Radiosurgery
Focused radiation beams converge onto tumour
X-knife: uses X-ray
Gamma knife: uses gamma ray
Cyberknife: uses real-time imaging and moves to adjust to movement (e.g. lung movement)
Disadvantages:
- ***Diffuse lesions respond less well
- Radiation necrosis can occur
- Size limit 2.5-3cm
Brain tumours
- Cerebral metastases
- Meningioma
- Neuroepithelial tumours / Glioma
- Pituitary adenoma
- Acoustic neuroma
- Cerebral metastasis
- Commonest intracranial tumour overall
- ↑ Incidence (∵ cancer survival improves)
- Haematogenous / Direct invasion (LN metastasis non-existent)
- Common origins: **Lung, Breast, Colon, Kidney, **Melanoma
- May present ***before the primary disease
- May develop when primary disease is long ***in remission + without extraneural metastasis
- Multiple lesions in a cancer patient can be something else (e.g. **Toxoplasmosis, **CNS lymphoma, ***Cysticercosis (pork tapeworm))
Cancer patients presenting with solitary brain mass
Top DDx: Metastasis (but cannot presume)
Other DDx: Primary brain tumour, Abscess (immunocompromised due to chemotherapy)
- History + Examination crucial
- Look for primary + screen for other foci
- **SPECT
- Serum tumour markers (not very helpful)
- Surgery + **Histology if in doubt
Aim of Surgery for Brain metastasis and Patient selection
Aim:
- Symptomatic palliation
- Maintain / Improve QOL
- Prolong life-expectancy
- Cure uncommon but not impossible
Tend to resect if:
- ***Single lesion (If multiple: Dexamethasone / WBRT)
- Something to palliate
- ***Low risk of causing deficit
- Young + Fit
- Systemic disease under control
- ***Reasonable life expectancy
Outcome of Brain metastasis
Median survival:
- Untreated ~1 month
- WBRT alone ~3-6 months
- **Surgery + **WBRT >=12 months
- Rarely surgery alone
- WBRT has significant SE —> Radiosurgery is now preferred
- Drugs that cross BBB (e.g. Chemotherapy) may improve outcome further
- Meningioma
- Arise from Arachnoid cap cells
- Risk: **Female, Radiation-induced, **Neurofibromatosis type 2
- Mostly benign (can be Atypical / Malignant)
Imaging:
- Dura-based lesion with Dura tail
- Strong **homogenous with **intense contrast enhancement
Treatment:
- Surgery (1st choice) (easy / very difficult e.g. encasing ICA)
- Radiosurgery (effective)
Prognosis:
- Generally good outcome
- Recurrence ~15%
- Neuroepithelial tumours / Glioma
Arise from Astrocytes, Oligodendrocytes, Ependymal cells etc.
Common: Astrocytoma (WHO grade 1-4) - Grade 4: Glioblastoma multiforme (GBM) —> middle-aged or above —> extremely malignant: infiltrative, rapid growth, invasive —> almost always recur —> life expectancy ~14 months
Treatment of malignant glioma
- WHO grade 3/4 glioma
1. Maximal safe surgical removal where feasible
-
**Chemoirradiation with **Temozolomide (TMZ)
- standard therapy
- alkylating agent
- Concomitant TMZ + Early radiotherapy (ERT), then adjuvant TMZ - ***Anti-angiogenesis agents (e.g. Bevacizumab)
- ***Tumour Treating Field (TTF)
- generate electric fields which interfere with cell division (esp. to actively dividing cells ∵ disrupt alignment of microtubules)
- Pituitary adenoma
- 20-25% at autopsy
- Micro (<1cm) / Macro
- Functioning / Non-functioning
Common presentation:
- ***Visual (Bitemporal hemianopia)
- ***Hormonal (Hyper / Hyposecretion)
- ***CN palsy (if extend into Cavernous sinus)
- Bleeding (Apoplexy)
- Hydrocephalus (at 3rd ventricle)
Treatment:
Hyperfunctioning
—> Prolactinoma —> ***Dopamine agonist (Bromocriptine, Cabergoline)
—> Others —> Surgery / Medical (GH, ACTH, TSH: Surgery first)
Non-functioning
—> Micro-incidentaloma —> Repeat MRI —> Tumour growth, Visual field abnormality —> Surgery / Radiosurgery
—> Macro-incidentaloma —> VF testing, Hypopituitarism
—> Normal —> Repeat MRI, Pituitary function, VF —> Tumour growth, Visual field abnormality —> Surgery / Radiosurgery
—> Abnormal —> Surgery / Radiosurgery
Surgical approaches:
- Craniotomy (***Transcranial approach)
- mainly when significant suprasellar extension - Microscopic / Endoscopic (***Transsphenoidal approach)
- less invasive but depends on tumour size + morphology
Complications of Transsphenoidal surgery
-
**Hypopituitarism
- lack of Cortisol —> **shock - ***Diabetes insipidus
- lack of ADH —> polyuria, haemoconcentration -
**CSF leakage + Meningitis
- CSF rhinorrhoea
- can occur in delayed fashion
- CT scan: Air in head, **Pneumocephaly
- ***Beta-2-transferrin +ve in fluid (found exclusively in CSF) - Visual loss
- ∵ damage to visual pathway
- close monitoring post-op - ENT symptoms
- epistaxis
- anosmia
- sinusitis - Vascular injury
- Intracranial haemorrhage
- Mortality (very rare)
Pituitary Aploplexy
Emergency —> acutely ***↑ ICP
- Acute haemorrhagic infarction +/- SAH
Presentation:
- Headache
- Visual loss
- **Acute pituitary failure (↓ ADH, **Cortisol, T4)
—> Cortisol insufficiency requiring replacement (which can predispose DI ∵ Cortisol ↑ renal perfusion —> further ↓ ADH release —> DI (may need Desmopressin))
—> ***Give Cortisol (most important) before T4 (may predispose Addisonian crisis if hypocortisolaemia not dealt with first ∵ T4 enhance hepatic metabolism of cortisol)
Treatment:
- Urgent surgery for decompression
- Acoustic neuroma
- **Vestibular schwannoma (arise from nerve sheath of CN8 (vestibular division))
- at **Cerebellopontine angle —> extend into **Internal acoustic meatus
- Bilateral in NF2
Presentation:
- ***Sensorineural hearing loss
- ***Tinnitus
- ***Cerebellar dysfunction
- Brainstem compression + ***Hydrocephalus
- CN5, 7 symptoms (occasionally)
Treatment:
- Surgery / Radiosurgery
Summary of Essential knowledge
- Presentation
- ↑ ICP symptoms
- seizure
- focal deficit (correlate with anatomy) - Pathology
- age
- location
- systemic disease (cancer, NF2) - Imaging
- location
- enhancement
- common DDx - Medical therapy
- Anticonvulsants (***only for Supratentorial)
- Steroids - Surgery
- Indication for resecting metastasis - Use of Radiosurgery
- Chemoirradiation for GBM
- Treatment principles for Pituitary adenoma + complications of Transsphenoidal surgery
