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astrocytes

brain tumors most commonly arise from this cell type

medulloblastoma

most common CNS tumor in children

sonic hedgehog

aberrant cerebellar granule cell formation via this pathway predisposes to medulloblastomas

somatic mutations

most gliomas are due to this type of mutation

meningiomas

most common CNS tumors seen in adults; not considered a malignancy

pilocytic grade I

the lowest grade astrocytic tumor
-typically indolent, have a limited invasive capacity, and rarely undergo anaplastic progression.

no symptoms

most common symptom for meningioma

seizures

low grade gliomas cause.......

mental status abnormalities

malignant gliomas and primary CNS lymphoma cause.......

cranial MRI

the only test needed to diagnose a brain tumor

supratentorial

herniations:
-uncal
-central
-cingulate
-transcalvarial

infratentorial

hernations:
-upward
-tonsilar

uncal herniation

-temporal lobe lesion protrudes through the tentorial notch
-structures impinged include the posterior cerebral artery, the contralateral peduncle and the midbrain
-neurological findings may be unilateral dilated pupil from ispilateral CN III compression, oculomotor palsy, homonymous hemianopsia, contralateral hemiparesis

central herniation

-midline tumor compresses basal ganglia, thalamus and midbrain
-neurological findings may be small pupils, lethargy, Cheyne-Stokes respirations

cingulate herniation

-medial frontal lobe tissue is pushed under the falx cerebri, anteriorly
-critical brain structures are typically not involved early on, and neurological s/s are not well defined
-this hernia syndrome is frequently an asymptomatic precursor to the other syndromes

transcalvarial herniation

-also called "external" herniation
-not usually a neoplastic event, but when generalize brain edema causes outward herniation through a fractured skull, or craniectomy
-may prevent closure from taking place

upward herniation

-one of the two posterior fossa herniations
-also called upward cerebellar hernation
-cerebellar signs, and some midbrain effects

tonsillar herniation

-AKA downward cerebellar syndrome
-posterior fossa tumors compress downward into the foramen magnum
-also called Chairi malformation
-neurological findings may be posterior headache, cough induced syncope, vomiting, respiratory changes
-Lhermittes sign: dysesthesias in the arms and legs with bending the neck forward

low grade astrocytoma (LGA)

-most common in young adults, children
-seizure is often first sign
-non-enhancing lesion on MRI with glucose hypometabolism

decision to operate

-age and performance status
-proximity to "eloquent" structures
-feasability of debulking
-feasability of complete resection
-in case of recurrence- time since last attempted resection

gamma knife, cyberknife, synergy S

-pin point radiation
-robotic arm vs. "helmeted" approach vs. computer-aided spin
-all intend minimizing collateral damage

GB therapeutic dicisions

-resect the resectable
-radiation to all (2 Gy fractions, 5 days/week, total of 60 Gy)
-Gliadel (biodegradable polymers soaked in carmustine) increased survival 11.6 to 13.0 mo
-concomitant XRT temozolmoide (capsules) improves survival. median survival was 16 months with 31% alive at 2 years
-stereotactic radiosurgery (3 cm or less)

meningioma

-20-25% of all intracranial neoplasms (menigothelial cell origin)
-MRI: convexities, parasellar, "dural tail"
-surgery for the symptomatic
-stereotactic radiosurgery for < 3 cm
-commonly found accidentally

hedgehog pathway

if this pathway is blocked, results in all translational pathways being turned on, thus leading to tumor formations

intracranial germ cell tumors

-pineal region in the majority
-signs and symptoms:
panhypopituitarism, diabetes insipidus, visual disturbances
-egg and sperm malignancy

human chorionic gonadotropin (HCG)

if GCT, this hormone will be elevated

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