Glioblastoma Flashcards
List some DDx for a new onset seizure?
- Neurological conditions- seizure (partial simple or complex), migraine, psychogenic non-epileptic seizure
- Vascular- haemorrhage (extradural, subdural, subarachnoid, intraventricular), ischaemia, berry aneurysm rupture, CVA (TIA, stroke/MCA)
- Neoplastic- glioblastoma, meningioma (30%), haemangioblastoma, Schwannoma, Oligodendroglioma, pituitary adenoma
- Infective- meningitis, abscess
- Metabolic- hypoglycaemia, hypo/hypernatraemia, hypocalcaemia, hypomagnesia
- Toxins- ETOH use, ETOH withdrawal
Differentiate between types of seizures?
1) Focal onset (partial) seizure
o Path: affects single area of the brain (commonly originating in medial temporal lobe) -> up precentral gyrus -> progression of symptoms (distal to proximal part of limb, then face ipsilaterally)
o Clinical: preceded by seizure aura (commonly), can generalise
o Types:
- Simple focal (aware)- consciousness intact
- Complex focal (impaired awareness)- impaired consciousness
2) Generalised onset seizure
o Path: diffuse areas of the brain affected
o Clinical: impaired awareness (almost always)
o Types:
- Absence (petit mal)- blank stare, no post-ictal confusion
- Myoclonic- quick, repetitive jerks
- Tonic- stiffening
- Tonic-clonic (grand mal)- alternating stiffening and movement
- Atonic (“drop seizures”)- fall to floor, mistaken for fainting
What are the differing indications for T1 and T2 MRI scans?
T1- used to differential anatomical structures (looks like normal anatomy)
o Bright- high fat tissues
o Dark- water-filled compartments
T2- examine compartments (looks like opposite of anatomy)
o Bright- components filled with water -> good for demonstrating pathology (most lesion assoc w increased water content)
o Dark- high fat content
Describe the pathogenesis of seizures secondary to glioblastoma?
Seizures- abnormal electrical discharge in CNS
- Due to alterations in surrounding brain tissue compressed by tumour OR tumour itself conducting abnormally
- Caused by overall brain dysfunction, not due to particular location
What anatomical structure is responsible for the symptoms of L hand and face weakness?
L hand and face weakness
- R precentral gyrus of frontal lobe (motor supply)
- Leg innervated by medial gyrus supply, head/arms by lateral gyrus
What anatomical structure is responsible for the symptoms of L hand and face numbness?
L hand and face numbness
- R post central gyrus in temporal lobe (sensory supply)
Describe the pathogenesis of a headache secondary to glioblastoma?
Headache- due to stretching/distortion of pain sensitive structures due to expansile lesion growth
Pain sensitive structures- meningeal arteries, venous sinuses, cranial nerves w sensory components, dura at base of brain
Explain why a patient had trouble with retaining memory?
Trouble retaining memory- indicates anterograde amnesia
• Dorsolateral prefrontal cortex of the frontal lobe- working memory (component of short-term memory)
• Hippocampus- storing working memory into LTM
• Limbic system, esp mammillary bodies (required for normal hippocampal function)- spatial memory
• Cerebral cortex- LTM stored
Describe the Limbic system?
- Function: regulates emotion, memories and arousal (stimulation)
- Components: cingulate gyrus, hippocampus, amygdala, fornix, mammillary bodies, thalamus
- Pathway
⇒ Cortex projects into the cingulate gyrus
⇒ Travels down to hippocampus -> fornix -> mammillary bodies
⇒ Mammillary bodies sense inputs to the hypothalamus to create physiological response
⇒ Mammillary body signals anterior nucleus of thalamus -> back to cortex
Differentiate between primary and secondary brain tumours?
CNS tumours can be primary or metastatic (50% each)
• Primary tumours- locally destructive, rarely metastasize
- Classified according to 5 cell types (astrocytes, olidendrocytes, ependymal, neuronal, meningothelial)
- Adult tumours occur above tentorium cerebelli, paeds tumours occur below (usually)
• Metastatic tumours- multiple, well-circumscribed lesion, often at grey-white junction
- Most common sources- breast, lung, kidney
Describe CNS histology?
• Comprised by neurons (50%) and glial tissue (50%, function to support neurons)
• CNS cell types:
1. Astrocytes- form BBB
2. Oligodendrocytes- myelinate axons
3. Ependymal cells- line ventricular spaces, producing CSF
4. Neuronal cells- transmit electrical activity, limited ability to divide (thus don’t form tumours)
5. Meningothelial cells- form inner-most meningeal sheath layer, direct contact with CSF
Describe glioblastoma multiforme?
Glioblastoma multiforme:
- Epi: most common malignant adult tumour, 1yr median survival
- Location: cerebral hemisphere, often crosses midline corpus callosum (“butterfly glioma”)
- Histo: necrosis (viable cells ring necrosis edge), endothelial cell proliferation
- Path: tumour of astrocytes, very aggressive
How would you manage a pt with seizures, secondary to glioblastoma?
• Focal neurology and vasogenic oedema – dexamethasone (glucocorticosteroid) and mannitol (osmotic diuretic, decrease CSF)
• Severe intracranial HTN, comatose – intubation, temporary hyperventilation
• Seizures- anticonvulsant (e.g. carbamazepine)
• Surgical resection dependent on grade
- If tumour inaccessible- radiotherapy or radiosurgery
• Serial MRI per 6/12 to assess changes, well-circumscribed morphology
