CNS Flashcards
(218 cards)
1
Q
What spinal level is end of cord?
A
L1/L2
2
Q
What level is the end of the cord in children?
A
L3/L4
3
Q
Spinal level of termination of thecal sac
A
S2
4
Q
Describe the flow of CSF
A
- Lateral ventricle
- Foramen of munro
- 3rd ventricle
- Aqueduct of Silvius
- 4th ventricle
- Foramen of Luschka (lateral) and foramen of magendie (medial)
5
Q
What are the contents of the cavernous sinus?
A
- Cranial nerve III, IV, V1, V2, VI
- Internal carotid artery
6
Q
Which is the first CN usually damaged with cavernous sinus problem
A
CN VI
7
Q
What CNS tumors associated with NF1?
A
Optic glioma
astrocytoma
8
Q
What CNS tumors associated with NF2
A
Schwannomas
Meningioma
Astrocytoma
Ependymoma
9
Q
What are the path hallmarks of glioblastoma
A
Nuclear atypia
Mitotic index
Endothelial proliferation
Necrosis
10
Q
What is the spectroscopy signal of tumor
A
Increased choline
Decreased creatine and NAA
11
Q
What is the spectroscopy signal of necrosis
A
Decreased choline
Increased lactate
12
Q
How to make diagnosis of molecular GBM?
A
- Histologic grade II or III astrocytoma
- IDH wt
- One or more of the following features
- EGFR amplification
- +7/-10 whole chromoscome gain/loss
- TERT promoter mutation
13
Q
What is first step for suspected HGG
A
Steroids if symptomatic
Maximally safe resection
14
Q
What to look for on path report for HGG
A
- MGMT methylation status
- IDH status
- EGFR amplification
15
Q
When should CRT start after surgery for glioblastoma
A
4-6 weeks
16
Q
What is the recommended treatment for glioblastoma (non elderly)
A
- Maximally safe resection
- RT to 60 Gy with concurrent and adjuvant temodar
- Can discuss adjuvant TTF with patient which had improved OS
17
Q
Dose of TMZ for concurrent CRT
A
75 mg/m2 daily (7d per week)
18
Q
Dose of TMZ adjuvant
A
150 mg/m2 (cycle 1)
200 mg/m2 (cycle 2-6)
Dosed first 5 days of month for 28d cycles
19
Q
How long does TTF have to be worn?
A
18+ hours a day
20
Q
What is the algorithm for elderly GBM
A
- High KPS: Stupp
- Normal KPS: 40/15 with TMZ
- Borderline
- TMZ alone if methylated
- RT alone if unmethylated
- 40/15
- 25/5
- Low
- Bev alone (if symptomatic)
- Best supportive care
21
Q
Best treatment for recurrent GBM
A
Enroll on clinical trial
Consider re-resection
22
Q
Dose of bev for glioblastoma
A
10 mg/kg q2w
23
Q
What is the best reRT dose
A
Enroll on trial
If off trial, 3.5 Gy x 10 to the contrast enhancement + 5 mm margin with bev if possible
24
Q
What is median OS for glioblastoma with Stupp
A
15 months
23 months if MGMT methylated
12 months if unmethylated
25
What is highest tox of TMZ?
heme tox (7%)
26
What is the definition of elderly for glioblastoma?
Roa: 60
Perry (w TMZ): 65
27
What was the OS difference from TTF?
5 months
| (21 months vs. 16 mos)
28
GBM volumes for Stupp
Fuse T1 post MRI and FLAIR
Contour T1post enhancing disease
Expand by 1.5 cm, adjust to cover all FLAIR+ disease and adjust off critical structures and natural anatomic boundaries
PTV margin of 0.5
29
Coverage target for HGG
\>95% PTV receives 100% of dose
30
What hotspot is acceptable for HGG
\<107%
31
Spinal cord tolerance
\<50 Gy
32
Brainstem tolerance (conventional fx)
\<55 Gy
33
Optic chiasm/nerve constraints (conventional)
\<54 Gy
34
Retina constraint (conventional fractionation)
\<45 Gy
35
Lens constraint (conventional fractionation)
Mean \<7 Gy
36
Target coverage for hypofractionated glioblastoma
Heterogeneity within 5% (hotspot \< 105%, cold spot \> 95%)
37
OAR constraints for hypofractionated glioblastoma
Brainstem, optics, eye, retina
All should not receive more than 100% of Rx'd dose
Lens mean \<4 Gy
38
What is expected OS for TMZ alone for glioblastoma
8 months
39
What is expected OS for RT alone for glioblastoma
5 months
40
What is the median survival after reRT and bev?
10 months
41
How often does progression occur on first post RT scan?
50%
42
Of the patients who progress early, how many are true POD?
50%
DO NOT CHANGE MGMT AFTER FIRST SCAN
43
For anaplastics, what should be asked about path report?
* Path - oligo or astrocytoma
* IDH status (trumps all)
* 1p19q codel status
44
What is IDH?
enzyme in Krebs cycle
45
What is PCV?
* Procarbazine
* CCNU (lomustine)
* Vincristine
46
How is PCV administered?
Procarbazine and Lomustine are oral
Vincristine is IV
47
How long is a cycle of PCV?
6 weeks
48
What is the pCV schedule?
Day 1- vincristine and lomustine
D1-10: procarbazine
32 days off
49
What percentage of anaplastic gliomas are enhancing?
2/3
50
How should anaplastic gliomas be classified
* If IDHwt --\> molecular glioblastoma
* If IDHmut
* 1p19q codel --\> molecular oligo
* 1p19q intact --\> molecular astro
51
How to approach IDHwt anaplastic gliomas?
Would treat like glioblastoma (on protocol)
60 Gy in 30 fractions with concurrent adjuvant TMZ
52
How to treat IDHmt anaplastic gliomas?
* Maximal safe resection
* If 1p19q codel --\> RT to 59.4 Gy --\> adjuvant PCV x 6 cycles
* If 1p19q non-codel --\> RT to 59.4 --\> adjuvant TMZ
53
What is the RT dose for anaplastic gliomas
59.4 Gy in 33 fractions of 1.8 Gy
54
How should chemo be given for anaplastic astro?
If IDHwt --\> concurrent/adjuvant
If IDHmt --\> adjuvant only (per CATNON)
55
What is the expansion for anaplastic gliomas
Cavity + 1.5 cm, include FLAIR
0.5 cm PTV margins
56
What is expected OS for anaplastic oligo?
14 years
57
What is expected survival for anaplastic astro, IDH mt
6 years
58
What are the path characteristics of pilocytic astrocytoma
Rosenthal fibers
Located in cerebellum or 3rd ventricle
Generally pts \< 25 years old
59
What LGG patients are considered high risk?
Age \> 40
STR
60
What are the negative prognostic features of LGG per EORTC
SATAN
* Size \> 6 cm
* Age \> 40
* Tumor crossing midline
* Astrocytic component (1p19q intact)
* Neuro deficits preop (including seizures)
61
Approach for high risk LGG
* Maximal safe resection
* RT to 54 Gy in 30 fractions
* If 1p19q codel --\> adjuvant PCV x 6 cycles
* If IDH mt but 1p19q intact --\> adjuvant TMZ
* If IDH wt --\> consider concurrent and adjuvant TMZ
62
Approach to low risk LGG
Maximal safe resection --\> observation
Reminder: age \<40, GTR
63
Approach to pilocytic astro
Maximally safe surgery
RT only if recurrence or biopsy
64
RT dose for pilocytic astro
1.8 x 28 = 50.4 Gy
65
Contouring for LGG
Contour FLAIR on MRI
CTV = 1 cm expansion, respect boundaries
PTV = 0.5 cm
66
What is 10 year OS for grade II oligo
75%
67
What is 10 year OS for grade II astro
45%
68
What percentage of the grade II tumors undergo malignant transformation?
50%
69
Does RT increase rate of malignant transformation for LGG?
No
70
What is the radiographic appearance of PCNSL
Homogeneous, multifocal
Periventricular
Crossing corpus callosum ![]()
71
What stage is PCNSL
Ann Arbor IE
72
What is the workup for PCNSL
Do not start steroids
MRI brain
MRI spine
PET CT
Testicular US for men \>60
73
Other workup needed for PCNSL
* LP
* Eye exam
* Brain biopsy if LP non diagnostic
74
Necessary labwork for PCNSL
* CBC
* CMP
* LDH
* EBV
* HIV
* Toxo
75
How to approach if bx negative on steroids
Hold steroids
Re-biopsy on progressions
76
Treatment approach for fit patients with PCNSL
* R-MVP x 5 cycles
* If CR --\> reduced dose WBRT --\> 2 cycles Ara-C
* If PR --\> 2 more cycles RMVP
* If CR after 7 cycles --\> rdWBRT
* If PR after 7 cycles --\> 45 Gy WBRT
77
What is R-MVP
Rituximab
High dose MTX
Vincristine
Procarbazine
78
How often is a cycle of RMVP
q2w
79
What is the dose of MTX for PCNSL
3.5 mg/m2
80
What should be treated for PCNSL
WBRT
Include posterior 1/3 of orbit (bb at lateral canthus with half beam block)
Cover to C2/C3
If ocular involvement, include bilateral orbits
81
Dose of WBRT for PCNSL
If CR to RMVP = 23.4 (1.8 x 13)
If PR to RMVP = 45 (1.8 x 25)
82
What is a low risk meningioma?
New grade 1 (any extent of surgery)
83
What is an intermediate risk meningioma?
* Recurrent grade I
* Grade II with GTR
84
High risk meningioma
* Recurrent grade 2
* New grade 2 s/p STR resection
* New or recurrent grade 3 (any extent of surgery)
85
Recommended treatment for low risk meningioma
Surgery --\> observation
86
Recommended treatment for intermediate risk meningioma
Surgery --\> 54 Gy
87
Recommended treatment for high risk meningioma
Surgery --\> 54 Gy with boost to 60 Gy to high risk region
88
How many meningiomas have a dural tail?
2/3
89
What is the path hallmark of meningiomas
psamomma bodies
90
How many mitoses for WHO grade I meningioma
\<4 per HPF
91
How many mitoses for grade II meningioma
4-19 mitoses
evidence of brain invasion
clear cell or choroid histology
92
Number of mitoses for grade III meningioma
20+ mitoses
rhabdoid histology
93
Which Simspon grades designate GTR?
I-III
94
What is Simpson grade IV resection
STR, 40% chance of symptomatic recurrence
95
What is Simpson grade V resection
Biopsy only
96
What is the recommended initial treatment for meningioma?
Get old scans, if first scan, consider obs if asymptomatic and small (\<3 cm)
Get new scan in 6 months
97
Fractionated RT dose for grade I meningioma
54 Gy in 30 fractions
98
Fractionated dose to grade II meningioma
If adjuvant after GTR = 54 Gy in 30 fx
If recurrent or STR = 54/60 in 30 fx
99
Fractionated RT dose for grade III meningioma
54/60 Gy in 30 fractions
100
SRS dose for meningioma
15 Gy x 1
only for grade I
101
What is max size for SRS for meningioma
3.5 cm
102
What is the SRS chiasm constraint
8 Gy MPD
103
How to do CTV for intermediate risk meningioma
* Contour postop bed and any gross residual
* Form CTV54 by doing 1 cm expansion
* Shrink CTV to 5 mm along natural boundaries including bone and brain if no involvement
* 5 mm PTV expansion
104
What is contouring for high risk meningioma
* Contour postop cavity and any residual enhancing disease
* Create CTV54
* Expand by 2 cm (reducing to 1 cm in natural boundaries)
* Treat to 54 Gy
* Create CTV60 using SIB
* Expand cavity+residual by 1 cm
* Treat to 60/30 Gy
* Do 5 mm expansion for both
105
Bilateral acoustic neuromas is pathognomonic for
NF2
106
What is the workup for an acoustic neuroma
Audiology
MRI IAC protocol
NF2 testing if bilateral
Clinical diagnosis but should see skull base surgeon
107
What is the scale for servicable hearing
Gardner-Robertson
108
What is the scale for facial nerve function
House-Brackman
109
What type of hearing loss is typically associated with acoustic neuroma
high frequency
110
What is management strategy for acoustic neuroma?
If asymptomatic, small, first scan --\> consider observation
Other options include surgery, EBRT or SRS
111
What is the LC for acoustic neuroma with EBRT vs SRS
Both excellent, \>90%
112
What is the hearing preservation rate with RT
~70%
113
How quickly do acoustics usually grow?
2 mm per year
114
If treating acoustic with conventional fractionation, what is the dose?
50.4 Gy in 28 Gy fractions
115
What is the contouring strategy for acoustic neuroma
* Contour GTV
* No CTV
* If EBRT --\> 3 mm margins
* If SRS --\> 1 mm margins
116
What dose for SRS for acoustic neuroma?
12.5 Gy x 1
117
What is needed to ensure SRS is done safely
AlignRT, facial surface recognition
118
What dose level is SRS planned to?
80% IDL (20% hotspot)
119
Which lesions might benefit from EBRT for acoustics?
Larger lesions
Very symptomatic
Lesions abutting brainstem or edema
120
What is the dose constraint for acoustic neruoma
Brainstem \< 12 Gy
Cochlea mean \< 4 Gy (this is not possible)
121
What is the rate of CN VII or CN V damage from RT for acoustic neuroma
\<10%
122
What share of acoustics enlarge after RT?
30%
123
Differential diagnosis for sellar/suprasellar mass
* Pituitary adenoma/carcinoma
* Craniopharyngioma
* Germinoma
* Optic glioma
* Meningioma
* Abscess
* Mets
124
What is inferior to sella?
sphenoid sinus
![]()
125
What is lateral to sella turcica?
cavernous sinus
126
What is in cavernous sinus
CN III, IV, V1, V2, VI
ICA
127
What hormones produced by posterior lobe of pituitary
ADH
Oxytocin
128
What is size definition of macroadenoma
\>1 cm
129
What are the symptoms of hyperprolactinemia
Galactorrhea
Amenorrhea
Decreased libido
Infertility
130
What is workup for pit tumor
Endo evaluation
Visual loss
CN exam
Optho consult for visual field testing
131
What is the classic ocular finding for pit tumor?
Bitemporal hemianopsia
![]()
132
What labwork should be sent/
Prolactin
GH or IGF-1
ACTH/Cortisol
TSH
FSH/LH
133
What is the prolactin level most likely a prolactinoma?
\>20 suspicious
\>200 very likely
134
What imaging to get for pituitary tumor
MRI brain with thin cuts through sella
Residual tumor can enhance with gad
135
What is the general treatment approach for pit tumors
* If asymptomatic and non-functional --\> observation
* If prolactinoma --\> medical management first
* If other secreting --\> TSS
* If inoperable --\> definitive RT
136
If patient has TSS which is STR what is next step
Generally Observe and give RT for recurrence
137
How to approach prolactinoma?
* Start with medical management even if visual symptoms
* Cabergoline 0.25 mg twice a week
* TSS if failure of medical mgmt
138
Role of RT for prolactinoma
Failed medical management and inoperable
Failed med management --\> TSS --\> persistent disease
139
How to approach functional pituitary tumors
* Push for surgery
* Can observe STR if asymptomatic and not near critical structures
* Adjuvant RT (6 weeks postop) if persistence of hormone secretion or STR
* All TSH-secreting tumors need postop RT
140
If you have a functional tumor, when should medicines be started
BEFORE surgery
141
If meds given preop for TSS, when should they be stopped
After surgery, before RT
142
Which functional tumor requires postop RT
TSH-secreting
54 Gy
143
How much space is required between tumor and chiasm to use SRS
At least 3 mm
144
In order to use SRS for pit tumors must respect what constraints?
Optics \< 8 Gy
Brainstem \< 12 Gy
145
Contouring pituitary tumor
GTV + 5 mm for EBRT
GTV + 3 mm for SRS
146
RT dose for non-functional pituitary adenoma
If EBRT - 45 Gy in 1.8 fx
If SRS - 14 Gy x 1
147
RT dose for functional pituitary adenomas
If TSH secreting - 54 Gy
If others - 50.4 Gy in 1.8 Gy
If SRS - 20 Gy x 1
148
What is cochlea constraint - SRS
Mean \<4 Gy
149
What is LC of pit tumors after RT
90%
150
What is rate of hormone normalization after surgery for pit adenoma
50-80%
151
Rate of hormone normalization after pituitary RT
30-50%
Can take 12-18 months
152
How many pit patients become hypopit after RT
50%
153
Which hormone is first to be lost after pituitary RT
GH (generally 3-5 years later)
154
How to manage DI?
Desmopressin
155
Why does DI occur from pit tumor
Damage to posterior pituitary, loss of ADH
156
For AVM, what is the workup
MRI and MRA
CT angio or IR angio
157
How to approach an AVM?
* If unuptured --\> observation
* If previous rupture options include
* Microsurgery
* SRS
* Embolization
158
What is the risk of hemorrhage with unruptured AVM?
2% per year
159
What is the recommended SRS dose for AVM?
If \<3 cm: 20 Gy to 50% IDL
If \>3 cm: 16 Gy to 50% IDL
160
How to approach if AVM is larger than 3 cm?
Consider staged procedures, 2 sessions 6 months apart
161
What is the target for AVM SES?
nidus of AVM, not feeding vessels
162
For SRS what is the V12 goal
\<10 cc
163
What is success rate of AVM obliteration with SRS
80-90%
Over 1-3 years
164
SRS dose for trigeminal neuralgia
80 Gy to 100% IDL
165
What is treatment for chordoma?
Maximally safe resection --\> RT (protons if possible)
166
Dose of RT for chordoma
If resected R0 --\> 60 Gy
If R1: 70 Gy
If R2: \>70 Gy
167
Management of spinal ependymoma
* Maximally safe resection
* If GTR and grade 1/2 --\> observation
* If STR --\> adjuvant RT
168
Dose of RT for spinal ependymoma
50.4 in 28 daily fractions of 1.8 Gy
169
SRS Brainstem Max - 1 FX
12 Gy
170
SRS max to optic chiasm and optic nerves
8 Gy
171
Cochlea constraint for SRS
Mean \< 6 Gy
MPD \< 12 Gy
172
Goal V12 for SRS
\<10cc
\<20% risk of necrosis
173
Goal brain dose for 3 fx SRS
V18 \< 30 cc (3 fx)
174
What is the SRS dose fall off
10% per mm
175
What is our SRS prescribed to
80% IDL
Linac based
125% hotspot
176
Brainstem - conventional
MPD of 54 Gy
D5% = 60 Gy if involved
177
Optic chiasm constraint - conventional
54 GY
178
Optic nerve constraint - conventional
54 Gy
179
Cochlea constraint - conventional
Mean \<45 Gy
180
Retina constraint - conventional
MPD of 45 Gy
181
Lens constraint - conventional
Mean \< 7 Gy
182
Spinal cord constraint - conventional
MPD \< 45 Gy
183
Hippocampal avoidance, dmax
16 Gy
184
Hippocampal avoidance, mean dose
9 Gy
185
Optics constraint 5 fx
5 x 5 MPD
186
Optics constraint 3 fx
18 Gy in 3 fx
187
Cochlea constraint - 3 fx
15 Gy / 3 fx MPD
188
Cochlea constraint - 5 fx
25 / 5 MPD
189
Brainstem constraint for 3 and 5 fx
allow D05% to be Rx dose (either 6x5 or 9x3)
190
Spinal cord constraint 3 fx
D0.35cc getting 18 Gy in 3 fx
191
Spinal cord constraint in 5 fractions
D0.35cc getting 23 Gy in 5 fx
192
Cauda constraint - 3 fx
D5cc 22 Gy / 3 fx
193
Cauda constraint 5 fx
D5cc - 30 Gy in 5 fx
194
Risk of permanent alopecia at 60 Gy
70%
195
How long until hair grows back after RT
2-3 months
196
How long after RT do cavernous malformations occur
years
197
Conformality index
Prescription isodose volume / tumor volume
198
Ideal conformality index
1
| (accept 1-2)
199
Heterogeneity index
Max dose to tumor / prescribed dose
200
Ideal heterogeneity index
\<2
201
Gradient index
Volume receiving 1/2 Rx dose / volume receiving 100% Rx dose
202
Ideal gradient index
~3
203
Steroid dose for BM
Loading dose of 10 mg
Standing dose of 4-6 q6 pending symptoms
204
Dose of SRS for 21 Gy
\<2 cm
205
Options for leptomeningeal disease
Clinical trial
Intrathecal or systemic chemo options
WBRT + focal spinal RT for symptoms
206
What is the advantage of WBRT + SRS
No OS benefit but decreases brain recurrence
207
Memantine dosing
Check kidney function
Week 1: 5 mg
Week 2: 5 BID
Week 3: 10 / 5
Week 4: 10 BID
208
Findings of hippocampal avoidance trial
Risk of cognitive failure was significantly lower after HA-WBRT plus memantine versus WBRT plus memantine
less deterioration in executive function at 4 months (23.3% v 40.4%; P = .01) and learning and memory at 6 months
209
What sequence should be used to contour hippocampus
T1
210
gray is gray on which sequence
T1
211
How to generate hippocampal avoidance zone
Contour bilateral hippocampus
5 mm expansion to create avoidance zone
212
What is PTV for HA-WBRT
whole brain parenchyma, excluding HA region
213
What is the PTV margin on brain for HA-WBRT
0 mm
214
What is the hippocampal volumetric constraint for HA-WBRT
D100% of \<9 Gy
215
MPD to hippocampus for HA-WBRT
\<16 Gy
216
What is the dose constraint to HA region
None, MPD and D100% is for hippocampus only
217
Guidelines for contouring postop cavities
Include entire surgical cavity using T1 post MRI
Include entire surgical tract
If tumor touching dura, include 5-10 mm extension along bone flap beyond region touching
If not touching dura, generally margin of 5 mm along bone flap sufficient
218
