Perez cns

arunmp's version from 2016-12-20 10:14

Perez cns

Question Answer
embryonal tumorsMedulloblastoma,cnsPNET,ATRT
CNS primitive neuroectodermal tumor (PNET)CNS neuroblastoma+CNS ganglioneuroblastoma+Medulloepithelioma+Ependymoblastoma
CSF spread medulloblastoma, PNET, germ cell tumors,CNS lymphoma,ependymoblastoma,pineloblastoma
Doubling time of astrocytoma20 days
Unique feature of intra cranial primary neoplasmdonot metastasize through lymphatics
Rare tumors causing xtracranial mets via hematogenous routehigh grade medulloblastoma+hemangiopericytoma+high grade astroctoma
Usual site of mets from brainlung
Medulloblastoma metastasize tobone+lymphnodes+peritoneal (vpshunt)
Seizure is mor common inlowgrade than high grade
The hypothalamic structures are located an additional1 cm superior to the sellar floor
  The pineal body (or the tentorial notch) usually sits approximately1 cm posterior and 3 cm superior to the external auditory meatus.
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The cribriform plate is the most inferior part ofthe anterior cranial fossa; it is an important reference point for the inferior border of whole-brain irradiation fields.
  In most patients, little distance is found between the lateral projections of the lens and the most inferior part of the cribriform plate.
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Selection criteria for brachytherapy in cns includetumor confined to one hemisphere, no transcallosal or subependymal spread, small size (<5 to 6 cm)
brachytherapy in cns isotope usediodine-125 (125I), and treatment is completed within 3 to 7 days.
Calcification incraniopharyngoma and odg
Grade 1 is pilocytic astrocytoma & grade 2 isgemistocytic
Mural nodulepilocytic astrocytoma and hemangioblastoma
Role of csi in ependymomaependymoBLASTOMa IS DEFINITE INDICATION,all other ependymoma if csf + or mri wise positive
Why ependymoma don’t need prophylactic CSIBecause spinal relapse are rare
Supratentorial Ependymoma30-40%
Infrratentorial Ependymoma40-60%
Supratentorial Ependymomahighgrade and poor prognosis compared to infratentorial
Ependymoma mribanana sign
Ependymoma orginatesfourth ventricle

Embryonal tumors as a group are the second most common type of CNS tumor in pediatric age group.

Question Answer
Embryonal tumors includeMedulloblastoma+supratentorial PNET+ATRT
MedulloblastomaDesmoplastic/nodular medulloblastoma +Medulloblastoma with extensivenodularity+Anaplastic medulloblastoma+Large cell medulloblastoma
Supratentorial PNETCNS neuroblastoma+Medulloepithelioma+Ependymoblastoma
The frequency of leptomeningeal seeding at diagnosisin medulloblastoma is approximately30% to 35%
Most common site of failureposterior fossa
CNS LmphomaGhost tumor (diappear with steroids)+cotton wool appearance in mri+associated with intraocular lymphoma
Meningioma sites of origincerebral convexities+falx cerebri+cp angle+sphenoid ridge
CSI indicationALL BLASTOMA --Medulloblastoma + Ependymoblastoma+ Pineoblastoma + Supratentorial PNET+Disseminated CNS germ cell tumours +Disseminated CNS lymphoma +Atypical Teratoid Rhabdoid tumour +Leptomeningeal carcinomatosis


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SELLA TURCICA MEASURES15mm APdiameter,12mm superoinferior
SELLA TURCICA MEASURESis in the sphenoid bone
Pitutary weight: 60MG
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MOst hormones arise fromanterior pituitary
Posterior pituitaryoxytoxin and adh
Pitutary tumors10% of brain tumors
---% of tumors are endocrinologicallly active70%
Rolre of ct scan in pituitary tumorsto know sellar sclerosis and pneumatisation
Non secreting tumors are made ofnull cell and oncocytes

secretory versus non secretory

Question Answer
Secretoryacidophilic tumors present with acromegaly and basophilic present with cushin disease
non secretorychromophobic are nonfunctioning tumors
acidophilicgh and prolactin
chromophobicnonfunctioning but occasional hyperprolactinemia


Adenomas are often classified by size
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Picoadenoma<0.3 cm
Microadenoma <1 cm


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Themost common surgical technique is through a transsphenoidalapproach
Fronta craniotomy) may be indicated for patients with extensive intracranial and skull-based involvement,in mpletely pneucomatised sphenoid+dumbbell shaped adenoma+lateral suprasellar xtension
Head position in rt in pitutaryflexed at 45
Planning 2d of pituitarypage 848
Nonfunctional adenoma are typically prescribed a dose of45 to 50.4 Gy given in 1.8- to 2.0-Gy daily fractions
secretory adenomas dosein the range of 50.4 to 54 Gy are recommended for
single fraction for nonfunctional adenomas 16 to 20 Gy in a frameless robotic radiosurgery platform.
single fraction for functional20 to 25 Gy
chiasma dose9Gy
curewhen all hormones r normal
hypopitutarism after rt islate complication (years)
Incidence of second malignancy1.6%


Question Answer
Intradural extramedullarymengioma+nervesheath tumor+vascular tumor
Extraduralmetaststic is most common +epidural hemangioma+lymphoma+lipoma+extradural meningioma
Ex tramedullary cause pain whyit can streach dura and pain is more on night and more with valsalva
Which part of spinal cord astrocytoma commoncervical and thoracic spine
Which part of spinal cord ependymoma commonlumbosacral spine


Question Answer
A reversible myelopathy can occur within --------months afterradiation therapy2 to 6 , no treatment required for this
Chronic, progressive, or delayed myelopathy can occurmonths to years after radiation therapy.
The latency period of chronic myelopathy has been reported to be bimodal with peaks of incidence occurringat 13 and 29 months.
Historically, the spinal cord has been limited to maximum doses of45 to 50 Gy with fractionation schedules of 1.8 to 2 Gy per day.
For conventionalexternal-beam radiation therapy at 1.8 to 2 Gy per day, a dose of 50 Gy, 60 Gy, and 69 Gy is associated with a0.2%, 6%, and 50% rates of myelopathy, respectively
However,pediatric patients and patients receiving potentially neurotoxic chemotherapy may have decreased spinal cord tolerance, with reports of myelopathyat doses 50 Gy or less
Data from the QUANTEC initiative indicate that the rate of myelopathy will be less than 1% with the maximum dose to the spinal cord limited to the equivalent of13 Gy in a single fraction or 20 Gy in 3 fractions
Themost commonly employed dose constraint for SRS is to keepless than 10% of the spinal cord (defined as 3 to 6 mm aboveand below the target volume) to less than 10 Gy
In human studies, where reirradiation is at least 6 months after the initial radiation course, essentially no cases of myelopathy were observed when the cumulative 2-Gy equivalent doses are60 Gy or less