Khan - Brain Tumors Flashcards
How common are brain mets?
- 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
How can the rate of change in ICP reflect the grade of the tumor causing it?
- 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
When should anticonvulsants be used in pts with brain tumors? Which ones should be avoided?
- 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)
What is the mainstay of tx for most brain cancers? Exception?
- 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
What are the 2 big chemo drugs to remember for brain cancer?
- Temozolomide
- Bevacizumab
What does malingering mean?
Pt is faking it
What is paranode syndrome?
- 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
What does bilateral abducens paralysis suggest?
Raised ICP (non-specific sign)
What are pressure waves? How can they be tx’d?
- 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
What is the survival rate of GBM?
- One of the worst tumors to have (survival <1%)
- NOTE: study where CMV infection tx’d, and survival rates were incredible
Briefly describe neuropoiesis (image).
How are tumor stem cells implicated in brain cancers? How does this affect their makeup?
- 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
Provide some examples of CNS tumors, and their cells of origin.
- 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
What are the most common primary brain tumors?
- # 1 = infiltrative astrocytoma
- # 2 = GBM
What are the 5 brain tumors we are responsible for? Categories?
- 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
What are the definitive and possible risk factors for CNS tumors?
- 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
What hereditary syndromes are associated with brain tumors (table)?
What is the relevance of a pressure-volume curve for brain tumors?
- 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)