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Flashcards in Tumor of The Central Nervous System Deck (45)
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1

Brain Tumor Epidemiology

-7.6/100,000 males, 5.4/100,000 females
-100,000 death/year from brain metastases
Prevalence: 122, 000
Lifetime Risk: 0.6%
-35% of patients will get brain metastases

2

Neuropoiesis

-development of mature neurons & their supportive glial cells from pluripotent stem cells is highly complex process controlled by cell growth promoting & suppressing genes

3

Primary Brain Tumors

-presence of tumor stem cells (including glial tumors)
-Glioma progenitor cells (astrocytoma, ependymoma, oligodendroglioma)
-Neuronal progenitor cells (neuronal tumors)
-can arise from any structure present intracranially (hemangioblastoma from blood vessels, neurofibroma & schwannoma from nerves, lymphoma from trafficking white blood cells, germinoma from nests of germ cells, meningioma from arachnoid cap cells, chordoma & chondrosarcoma from bone, or an extracranial cancer may enter brain via blood stream (metastases)
-developmental cysts may mimic a brain tumor

4

Primary Brain Neoplasia Frequency

-meningioma & mixed oligoastrocytoma 2%
-glioblastoma multiforme 40%
- infiltrative astrocytoma 42%

5

Risk Factors for CNS Tumors

Definitive:
-ionizing radiation
-immunosuppression (latrogenic, chemo, acquired AIDS)
-genetic syndromes

Possible:
-electromagnetic fields (cell phone)
-diet, occupation, infections (HIV, EBV, HTLV)

6

Pathogenesis of Brain Tumor

-cell growth genes must be over activated or inhibitor genes have to be silenced

7

Pressure Volume Curve & Intracranial Pressure Waves

-cerebral perfusion pressure is difference b/w mean arterial pressure intracranial pressure (CSF & interstitial pressure)
-as intracranial volume slowly inc. pressure remains constant until brain compliance threshold is reached, then small inc. in volume causes large inc. in pressure
-may exceed cerebral perfusion pressure and cause focal weakness, numbness, mental status change to seizure like activity
***Plateau wave phenomenon***

8

Signs of CNS Tumors: Headache

-due to raised intracranial pressure or local irritation
-often non-specific but may have migraine features
-suspect tumor if: worsen on awakening with improvement in 1 hr, new onset at any age, change in character or severity of headaches in a chronic headache patient

9

Signs of CNS Tumors: Vomiting

-may or may not be associated with nausea
-occurs more often on awakening
-more common in children
-suggests tumor if immediately follows an acute onset headache suggesting inc. ICP

10

Signs of CNS Tumors: Mental Status Changes

-depression, irritability, apathy

11

Signs of CNS Tumors: Papilledema

-often asymptomatic (may have visual changes)
-more common in children & young adults when compared to elderly
-

12

Signs of CNS Tumors: Seizures

-partial (focal) or generalized seizures
-episodic alterations in smell, taste, personality, memory, motor or sensory function depending on the origin of neural discharge

13

Signs of CNS Tumors: Focal Neurologic Deficits

-vary depending on location
-includes: weakness (pre-central gyrus), paresthesias (post-central), visual impairment (optic pathway/occipital lobe), personality changes (frontal lobe)
-may be reversible depending: cause (tumor invasion vs. edema vs. compression
-time since onset of deficit

14

Etiology of Signs & Symptoms of CNS tumors

-invasion of neuronal or vascular structures
-compression of adjacent neural or vascular structures
-obstruction of CSF pathways - hydorcephalus - inc. ICP
-Herniation from mass effect
-cerebral hypoperfusion b/c of inc. intracranial pressure

15

Brain Herniation

1. Subfalcine herniation of cingulate gyrus, may compress ant. cerebral artery & CVA
2. diencephalic downward herniation, compression of upper brainstem causes drowsiness, impaired vertical gaze and uni or bilateral small pupils b/c of sympathetic fiber involvement (horner)
3. Classical uncal herniation (ipsilateral oculomotor nerve palsy & contra or ipsilateral hemiparesis)
4. Upward herniation through tentorium (ipsilateral oculomotor, Horner, and contralateral hemiparesis)
5. Tonsillar herniation (BP changes, weakness, respiratory disturbance, weakness & Horner syndrome)

16

CNS Tumor Diagnostics

-H&P
-MRI (contrast enhancement optional), study of choice for suspected tumor
-MRI superior to CT differentiation tumors from vascular malformations & other lesions but CT better identifying calcifications & pathology
-diagnosis by biopsy except primary CNS lymphomas (found in CSF by lumbar puncture)

17

TI weighted MRI Scan

-water is hypointense (dark), dec. signal or darker than surrounding brain
-injected contrast that leaks across disrupted BBB within tumors appears hyperintense (bright), inc. signal or brighter than surrounding brain

18

T2 weighted MRI Scan

-CSF/edema/tumor appears hyperintense (bright)
-Differentiating edema from infiltrating tumor on T2
edema spares the cortex
tumor does not spare the cortex

19

Glioma

-tumors that are derived form supporting glial cells of the CNS
-Subtypes: astrocytoma, oligodendroglioma, ependymoma
-most common primary CNS tumor (>50%)
-low grade (younger), high grade (older than 50)
-Grade 1: juvenile pilocystic astrocytoma
-Grade 2: Low-grade astrocytoma
-Grade 3: Anaplastic astrocytoma
-Grade 4: Glioblastoma multiforme (grade 4, most common)

20

CNS Tumors: Symptomatic Rx

1. Steroids (decadron, dexamethasone)
-reduces vasogenic edema & improves intracranial pressure
-dramatic but temporary improvement in neuro symptoms
2. Anticonvulsants (non-hepatic enzyme inducing)
-given for focal or generalized seizures caused by the tumor
-no evidence supporting use prior to seizure onset except for patients undergoing surgery (1 week)

21

CNS Tumors: Definitive Rx

-Observation: reserved for tumor not lifethretening, slow growing, asymptomatic, or symptoms can be controlled by meds
-Surgery: 1st line treatment for accessible tumors, establishes pathologic diagnosis, improves ICP & seizure control, prolongs survival
-Radiotherapy: adjunct to surgery for high-grade, may be delayed in low grade, needed for eradication of infiltrative micro-populations of cells missed with resection

22

Risk of Radiation Treatment

-cognitive decline
-stroke
-secondary cancers

23

Radiation Modalities

-conventional
-conformal
-radiosurgery
-brachytherapy
-proton therapy

24

CNS Tumors: Adjuvant Rx

-Chemo: single-agent IV bis-chloroethyl-nitrosourea (BSNU; carmustine), single-agent oral Temozolomide (current treatment of choice), combo (PCV) of procarbazine, chloroethyl-cyclohexyl nitorsourea, and vincristin
-Biological Agents (anti-angiogenesis Bevacizumab for anti-glioma treatment (FDA approved))
-Others being studied: gene, immuno, viral therapy

25

CNS Tumors: Prognostic Factors

-better survival: younger age, good performance status, tumor grade & histology, degree of tumor resection, O(6)-methyl guanine-DNA methyltransferase methylation
-isocitrate dehydorgensase mutation
-1p and 19q deletion in oligodendroglioma

26

Meningioma

-2-10% of primary brain tumors
~45yr women>men
-derived from arachnoid membrane (arachnoid cap)
-slow growing benign tumors
-subtypes: low grade (most common), atypical, malignant
-Location: convexity, parasagittal, optic sheath
-Imaging: dark on T1, Bright on T2, enhance with contrast, maybe calcifcations on CT, dural tail
-spindle shaped cells arranged in sheets & whorls, & tail of enhancement over dura extending from tumor edge

27

Meningioma: Treatment & Prognosis

-observation vs. surgery and/or radiotherapy if <3cm
-prognosis: very good relative to most other types of brain tumors

28

Pituitary Tumors

-10-15% of all primary brain tumors
-most commonly derived from anterior pituitary
-Microadenomas (1cm): most often no hormones, often grow large enough to cause compression & hypofunction of pituitary gland or compression of the pituitary stalk

29

Pituitary Tumor: Signs & Symptoms

-Headache
-Endocrine dysfunction (galactorrhea - XS prolactin, acromegaly - XS GH)
-Visual field defects: bitemporal hemianopsia starting with upper quadrant (compression of chiasm), unilateral blindness (optic n. compression)
-diplopia (invasion of cavernous sinus compressing CN III, IV, VI)
-Facial numbness (invasion of cavernous sinus compressing CN V)

30

Pituitary Tumors: Diagnostics

-MRI with and without contrast: Serum hormone levels (endocrinology), visual fields test (ophthalmology)