Khan - Brain Tumors Flashcards
1
Q
How common are brain mets?
A
- Estimated 35% of cancer pts will devo brain mets
- REMEMBER: these are the most common brain tumor
- NOTE: brain tumors are relatively less common compared to other cancers
2
Q
How can the rate of change in ICP reflect the grade of the tumor causing it?
A
- P-V curve: progression to right side of the curve may take years in low-grade tumor
- INC ICP will happen more rapidly in malignant, high grade tumor
3
Q
When should anticonvulsants be used in pts with brain tumors? Which ones should be avoided?
A
- Seizures are treated ONLY if they occur
- Use anticonvulsants that do NOT induce hepatic enzymes
1. Do NOT use valproic acid bc it affects PLTs (can cause thrombocytopenia)
4
Q
What is the mainstay of tx for most brain cancers? Exception?
A
- RADIATION is still the mainstay of tx for most cancers
- Only brain tumor for which radiation is not the mainstay of tx is CNS lymphoma bc chemo is very effective
5
Q
What are the 2 big chemo drugs to remember for brain cancer?
A
- Temozolomide
- Bevacizumab
6
Q
What does malingering mean?
A
Pt is faking it
7
Q
What is paranode syndrome?
A
- PRESSURE ON TECTUM, usually due to a tumor of the pineal gland (glioma or germinoma)
- This is a dorsal midbrain syndrome where pts can’t look up due to pressure on Oculomotor nuclei sup rectus fibers from the medial nucleus -> dysfunctional
1. Nucleus of Cajal in midbrain works like PPRF for vertical gaze - Also puts pressure on aqueduct, which can lead to hydrocephalus and headache
- Non-specific effect of abducens paralysis: this can happen anytime you get ICP; speculation that this happens over petrous bone
8
Q
What does bilateral abducens paralysis suggest?
A
Raised ICP (non-specific sign)
9
Q
What are pressure waves? How can they be tx’d?
A
- PRESSURE WAVES: INC intra-thoracic pressure leads to momentary reduction in drainage of venous fluid from the brain -> small INC in non-compliant brain causes exponential rise in CSF pressure, which can offset perfusion pressure of the brain
1. May lead to transient visual obscurations (BLURRING)
2. Post pressure (basilar - PCA) < anterior, and more susceptible to these changes - TX: reduce pressure -> spinal tap to detect pressure of tumor cells and cell markers of different cell types
1. If you do this at wrong time, you CAN KILL THE PT, i.e., tonsillar or other herniation -> will lead to respiratory arrest (Arnold Chiari)
2. CURATIVE in terms of symptoms if all CSF pathways normal
10
Q
What is the survival rate of GBM?
A
- One of the worst tumors to have (survival <1%)
- NOTE: study where CMV infection tx’d, and survival rates were incredible
11
Q
Briefly describe neuropoiesis (image).
A
12
Q
How are tumor stem cells implicated in brain cancers? How does this affect their makeup?
A
- Growing evidence supports presence of tumor stem cells in different cancers, incl. GLIAL TUMORS
- Glial tumors are differentiated into different types and may have different clinical behavior
- Mixed glial/neuronal tumors also possible containing neoplastic neuronal and glial components:
1. GANGLIOGLIOMA - Mixed glial tumors also possible, e.g., OLIGO-ASTROCYTOMA
13
Q
Provide some examples of CNS tumors, and their cells of origin.
A
- Hemangioblastoma: from blood vessels
- Neurofibroma/SCHWANNOMA: from NN
- LYMPHOMA: from tracfficking WBC’s
- Germinoma: from nests of germ cells
- MENINGIOMA: from arachnoid capillary cells
- Chordoma/chondrosarcoma: from bone
- Extracranial cancer may enter via blood stream (mets)
- NOTE: these can arise from any structure present intracranially; devo cysts can also mimic brain tumor
14
Q
What are the most common primary brain tumors?
A
- # 1 = infiltrative astrocytoma
- # 2 = GBM
15
Q
What are the 5 brain tumors we are responsible for? Categories?
A
- PRIMARY CRANIAL:
1. Intra-axial:
a. Glioma
b. Pituitary
c. Lymphoma
2. Extra-axial: external to brain parenchyma
a. Meningioma
b. Acoustic neuroma - NOTE: don’t forget about mets and spinal cord tumors
16
Q
What are the definitive and possible risk factors for CNS tumors?
A
- DEFINITIVE: ionizing radiation
1. Immunosuppression: iatrogenic, chemo, AIDS
2. Genetic syndromes - POSSIBLE: electromagnetic fields, incl cell phone use
1. Diet, occupation
2. Infections: HIV, EBV (linked to CNS lymphoma in immunosuppressed pts, esp. after bone marrow transplant and in AIDS), HTLV
17
Q
What hereditary syndromes are associated with brain tumors (table)?
A
18
Q
What is the relevance of a pressure-volume curve for brain tumors?
A
- Cerebral perfusion pressure is difference bt MAP and ICP (CSF and interstitial pressure)
- As intracranial volume slowly INC (see graph), such as with tumor growth, ICP remains fairly constant until compliance threshold reached
- At this stage, small volume INC causes large INC in ICP -> PLATEAU WAVE (other card)
19
Q
What is the plateau wave phenomenon?
A
- Once ICP reaches compliance threshold (due to growing tumor), small volume INC causes large INC in ICP
- At this stage, intermittent INC in ICP (see graph) may exceed cerebral perfusion pressure (plateau waves) and cause multiple symptoms:
1. From focal weakness, numbness, mental status changes, and seizure-like activity (global or focal hypovolemia in the brain) - Aka, plateau wave phenomenon
23
Q
What are the 5 brain herniation mechanisms?
A
- 1) Subfalcine herniation of cingulate gyrus: may compress ACA and CVA
- 2) Diencephalic downward herniation: compression of upper brainstem causes drowsiness, impaired vertical gaze (SUNSET SIGN), and uni- or bilateral sm pupils due to involvement of SYM fibers (Horner’s)
- 3) Classical uncal herniation: ipsilateral CN III palsy and contra or ipsilateral hemiparesis
- 4) Upward herniation through tentorium: may cause ipsilateral CN III, Horner (mid-position unreactive pupil) and contralateral hemiparesis
- 5) Tonsillar herniation: BP changes, weakness, resp disturbance, weakness, Horner
25
Q
What are the 2 types of MRI?
A
- T1 WEIGHTED: water (i.e., CSF, tumor, edema) is hypointense (dark), so DEC signal or darker than surrounding brain
1. Injected contrast that leaks across disrupted BBB w/in tumors hyperintense (bright), so INC signal or brighter than surrounding brain - T2 WEIGHTED: CSF/edema/tumor hyperintense (bright) -> can differentiate edema from infiltrating tumor bc edema spares cortex and tumor does not
1. Stationary and moving water both bright/white
26
Q
What type of MRI is this? Difference bt the 2 images? What do you see?
A
-
T1 weighted MRI
1. LEFT is T1 and RIGHT is T1 with contrast - Large ring enhancing tumor in L frontal lobe, incl mass effect with midline shift
- Tumor has grown rapidly, outstripping its blood supply, and leading to central necrosis (dark area)
- All of these are indicative of a highly malignant tumor, most likely a grade IV astrocytoma (GBM)
28
Q
How does histo grading work for gliomas?
A
- Lowest grade: well-differentiated, no nuclear atypia, and low mitotic index
- INC de-differentiation, higher mitotic index, vascular proliferation, necrosis determine higher tumor grade
- NOTE: tumor blood vessels have immature BBB, resulting in leakage of dye on MRI imaging
29
Q
What are the imaging and histo features of gliomas (low-grade vs. high)?
A
-
LOW-GRADE are infiltrative, slow-growing, and do NOT produce severe mass effect
1. Hyperintense on T2 or FLAIR images (L upper image) and do NOT enhance with contrast (right image upper row T1 after contrast) - Note features of a HIGHLY MALIGNANT glioma in the bottom row: an ENHANCING MARGIN, necrotic center, surrounding edema, MASS EFFECT
37
Q
What are the histo and imaging features of meningiomas?
A
- Spindle-shaped cells arranged in sheets and whorls, and tail of enhancement over dura extending from tumor edge (dural tail)
- Diffuse enhancement
- May spontaneously involute and calcify, or cause symptoms by compressing other brain structures
- Majority are low-grade tumors
40
Q
What are the diagnostics and txs for pituitary adenomas?
A
- DX: MRI w/and w/o contrast, serum hormone levels (endocrine), visual fields testing (ophthalmology)
- TX: observation
1. SURGERY: 1st-line for most tumors, and low morbidity/mortality w/experience neurosurgeon
2. RADIOTX: adjunct for invasive tumors or sub-total resection; for recurrent, unresponsive, or very small tumors not directly adjacent to vital structures like optic N (late cxs incl: damage to optic NN, hypopituitarism, hypothal dysfunction, and secondary malignancy)
3. PHARMACOTX: Bromocriptine and Pergolide (dopamine agonists for PRL; often reduction in tumor size by up to 80%)
a. Octreotide: somatostatin for GH-secreting
b. Replacement therapy for pituitary hypofunction
41
Q
What are the features of acoustic neuromas?
A
- Aka, vestibular schwannoma: origin is Schwann cells surrounding vestibular portion of CN VIII; most often arise in internal auditory canal, cerebellopontine angle
- Middle-aged adults (M = F)
- Benign, slow-growing tumors that present w/: hearing loss, tinnitus, headache, dizziness, facial numbness or weakness
- TX: observation, sx excision (excellent outcome), or radiosurgery
- NOTE: bilateral acoustic neuromas pathognomonic for NF2 (chrom 22)
1. Schwannomas can also arise from other CN’s, and even spinal radicles (densely packed and cystic areas on histo)
42
Q
What are the features of CNS lymphoma (dx, tx, prognosis)?
A
- Commonly affects leptomeninges + deeper peri-ventricular brain parenchyma
1. On the rise, and a malignant transformation of trafficking B-lymphos - DX: MRI w/contrast may show multiple uniformly enhancing masses w/little or no edema and LP may show monoclonal pop of B-cells in CSF (vitrectomy for tissue dx if ocular involvement)
- TX: if lymphoma suspected, withhold steroids until time of biopsy bc will cause rapid necrosis and poor specimen for patho; chemo (high-dose MTX crosses BBB, Vincristine, Procarbazine), radiotherapy
- PROGNOSIS: months for steroids alone; 1 year for tx with radiation; 3-4 yrs after tx w/chemo + radiation (cure possible in younger pts; highly chemo/radio sensitive)
1. Extent of resection not a prognostic marker - NOTE: round blue cells, and may be caused by EBV infection in immunocompromised patients
43
Q
What tumors met to the brain? Dxs?
A
- More common/equally as devastating as high-grade glioma
- TYPES: 50% small/non-small cell LUNG cancer (most comm brain mets in M)
1. 15-20% BREAST: most comm brain mets in F
2. 10% melanoma: highest propensity to met here
3. 5% colon cancer
4. Renal cell carcinoma
5. 10% unknown primary - DXs: primary workup, if indicated (head-to-toe + serum Ca markers), MRI with contrast -> discrete single or multiple solid or ring-enhancing nodules
1. Significant amt of edema out of proportion to size of nodules
46
Q
What are the signs and symptoms of spinal cord tumors? Classifications?
A
- Depend on location, but can be:
1. Pain: most common presenting symptom
2. Weakness + UMN/LMN motor findings
3. Paresthesias - CLASSIFIED based on origin (primary or metastatic) and location:
1. Extra-dural: majority are spinal METS (70% of spine mets: breast, lung, prostate, RCC, lymphoma, sarcomas)
2. Intra-dural extramedullary: schwannomas, neurofibromas, meningiomas
3. Intradural intramedullary: astrocytomas (most common in peds), ependymoma (most comm in adults), hemangioblastoma
