OPTICPATHWAYGLIOMA - Optic pathway gliomas are a type of low-grade brain tumor that affects the optic nerves and chiasm. They occur most commonly in young children under 5 years of age. - These tumors are often indolent but can cause vision loss, eye abnormalities, and hormone deficiencies. About 1/3 of patients have neurofibromatosis type 1. - Treatment involves monitoring smaller tumors, chemotherapy for younger patients to delay radiation, and radiation therapy for older children or progressive disease. Surgery may be used in select cases. Long-term risks include additional tumors, cognitive effects, and endocrine dysfunction.

1. OPTICPATHWAYGLIOMA

2. • 1%ofCNStumors
• 3-‐5%ofpediatrictumors
• 65%ofpatientsareyoungerthan5yearsof age
• Occurwithequalfrequencyinmalesand
females
• Majorityarepilocyticastrocytomas
• Indolentnature,CSFdisseminationisrare
• 25%occurinopticnerve;60%involvethe chiasm
• 1/3ofpatientswithOPGhave
neurofibromatosis1(NF1)

3. • Pilomyxoidastrocytoma(PMA)
– SubtypeofPA
– atayoungerage
– monotonous ,bipolar spindle cells with an
angiocentric arrangement within a myxoid
background
– localrecurrence55-‐76%
– CSFdissemination-‐11-‐14%

4. ClinicalFeatures
• Spectrumoffindingsrangingfromlesions confinedto
justtheopticnerve,lesions affectingtheopticchiasm
andhypothalamus andlesionswithdiffuse
involvementofalarge partofopticpathway.

5. • Decreaseinvisualacuity,visualfielddeficits(85%ofpts)
• Acutevisualloss(hemorrhage)
• Proptosiswithdeviationofaffectedeye
• Suprasellargliomasextendingintothirdventricle cause
obstructivehydrocephalus
• Macrocephaly,failuretothriveininfancy
• Headache,vomiting,decreaseinschool
performance

6. • 50%ofchildrenhaveendocrineabnormalities
• MostlyGHdeficiencyandprecociouspuberty
• Precociouspubertyismorecommonin
patientswithNF1
• Diabetesinsipidusisrare(morecommonwith
germinoma,craniopharyngioma)
• Diagnosisisoften delayed,tumorscanbe large
atdiscovery

7. • Diencephalonsyndrome:
• DescribedbyRussel
• Attributedtoleptin–ghrelinsystem
• Manifestaslackofweightgainand emaciation
• Normaloralintakeandheight
• Nystagmus,torticollis,headbobbing(rare)
• Rarecauseoffailuretothrive

8. Imaging
• PlainXray–
– enlargedopticcanal
– J shapedsellaturcica
• CTscan
– Enlargementofopticnerve
– Calcificationorcysts(d/d –
meningioma,craniopharyngioma)
– HypodenseonNCCT,variableenhancementon
contrast

9. • MRI
– Imagingofchoice
– Canbeusedtomonitorprogressionorresponse to
treatment
– Hypo-‐isoonT1,hyperonT2
– Variableenhancementoncontrast
– Cystformationaroundasolid tumor
– Fusiformenlargement,elongatedlengthofoptic nerve
– redundancyofthenerveinthemidorbitis
characteristic
– (comparewiththeoppositeside)

10. Assessment of Optic Pathway Gliomas
o Pediatric OPGs do not enhance homogeneously and enhancement not
indicative of progression/response
o Pediatric OPGs have very slow grow rate overtime (stable disease =
response to therapy)
o OPGs c
o Associ
linico-radiological discrepancy
ation with NF1 makes things complicated
F-U 9 months
3 year-old
Eur. Radiol. 10, 1076-1078 (2000)
There is no MRI criterion predictive of tumor
growth and prognosis; moreover there is no
correlation between tumor enhancement, internal
structure and the tumor clinical course!

11. • Smallchiasmaltumorsshowexpansionof
chiasm
• Largeglobularsuprasellargliomasshow
extensionintothirdventricle
• Gliomasofchiasmandhypothalamusare often
indistinguishablebecauseoflackof anatomic
borderbetweenthesestructures.
• Enhanceheterogenouslyoncontrast(d/d
germinomawhichenhancesuniformly)

12. • Diffuseopticpathwayglioma
– Affectstheentireopticpathway
– morecommonwith NF1
– B/l involvement-‐“mustache”sign
– Variablepatternofgrowth
– Highincidenceofprecociouspuberty(25%)
– Manifestsinyoungerage(2-‐3years);females
– Assocothercongenitalabnormalities

13. • CTA/MRA
– VisualizetheCircleofWillisinassocwith suprasellargliomas
• MRS
• Increasedcreatine–cholineratio
• DecreasedNAApeak
Diffusion-‐weightedMRImaybeparticularly usefulinNFpatients,asithasbeen
shownto moreeffectivelydifferentiateopticgliomasfromhamartomasand
myelinvacuolization thanothermeans

15. RoleofVEP
• SensitivemethodofdetectingOPGs
• It isanelectrophysiologicalmeasureofthe
integrityofthevisualpathway
• SerialVEPswouldbehardtointerpret becausesmall
changesinamplitudeanddelay withoutchangesin
visionareofuncertain clinicalsignificance

16. OCT

18. Differentialdiagnosis
• Pituitaryadenoma
• Craniopharyngioma
• Germcelltumour
• Hypothalamichamartoma

19. The current recommendations for screening of patients with NF1 for
OPHGs
• Baseline “screening” neuroimaging or visual-evoked potential
measurements of
asymptomatic children with normal visual examinations is not warranted.
• All children with NF1 who are younger than 8 years should undergo an
annual ophthalmologic examination that should include measurement of
visual acuity,confrontation visual field evaluation, color vision testing, and
assessment of pupils, eyelids, ocular motility, irises, and fundi. Formal
computerized or kinetic testing of visual fields may also be performed if
the patient is reliable, but this step is not necessary. It is recommended
that, when possible, these evaluations be performed by an
ophthalmologist or neuro-ophthalmologist skilled in testing
young children with NF1.

20. • Children with NF1 who are older than 8 years are at a significantly lower risk for
the development of OPHG. The interval at which ophthalmological examinations
should be performed and at what age they may be discontinued is unknown. It is
recommended that children in this age group receive complete eye examinations
every 2 years until 18 years of age.
• No specialized ophthalmologic follow-up is necessary for adults with NF1 excep
for routine eye care.
• All children with NF1 should undergo yearly measurements of weight and height
plotted on standard growth charts, with the aim of looking for the first sign of
precocious puberty.
• There is insufficient information available to make an evidence-based
recommendation on the evaluation of children younger than 1 year.
• In those uncommon situations in which reliable eye examinations cannot be
performed, there may be a role for neuroimaging.

21. Treatment
• Incidentallydetectedwithoutsignificant symptomscan
befollowedwithserialimaging
• If diagnosisisuncertain,biopsymaybe
performed

24. Chemotherapy
• Consideredtobethefirstlinetreatment
• FewersideeffectsthanwithRT
• <3Yrsit istheonlyadjuvanttreatment because
intellectualandotherfunctionsare wellpreserved
• 5yearrecurrencefreesurvivalremainsabout 60%
• EffectivelypostponesRT
• Childrenwithdiencephalonsyndrome improve

25. • Useofconcurrentcarboplatinandvincristine ina10-
‐week induction phase, followed by 48 weeks of
maintenance
• Thisregimenresultedinaprogression-‐free survival
(PFS)of75%at2yearsand68%at3 years.Children
aged5yearsoryoungerhada notablymorefavorable
overallrateof response.
• 10yearsurvivalis74-‐96%after chemotherapy
withorwithoutsurgery
• Chemotherapyimprovesqualityoflifeby eliminating
ordelayingRT
• PackerRJ,AterJ, AllenJ, etal.Carboplatinandvincristineforchildrenwithnewlydiagnosedprogressivelow-‐gradegliomas.J Neurosurg 1997;86:747–754.

26. • Surgicalapproach
– subfrontal
– pterional
– Anteriortranscallosal
• Surgicalresectionisusefulinchildrenwithno useful
vision,severeeyethreateningvision proptosisora
painfuleyethathasnotresponded tochemotherapy
• If botheyesareaffected,noindicationforsurgery is
present

27. • Surgery
– Subfrontalapproachwithorbitalunroofing
– Affectedopticnerveisexcisedfromtheglobeto the
chiasm(leave2-‐3mmfromthechiasmto preserve
decussatingfibersfromtheopposite eye)
– AvoiddamagetoLPSandocculomotornervesto avoid
undesirableproptosis
– Orbitalroofmust reconstructedtoavoid
undesirableproptosis

28. • Chiasmalhypothamictumours
– 50%ofptshaveobstructivehydrocephalus
– Fenestrationofseptumpellucidumor
biventricularshuntmayberequired
– ETVisnotfeasible
– Surgicaltreatmentisusuallydelayeduntil
symptomsappear
– Tumordebulkingcanbeperformedfor
progressivetumors

29. • Incompletesurgicalresectiondoesnotaffect survival
• Provideshistologicalverification,
cytoreduction,increasesCSFflow
• Risks– visual,endocrinedisturbances,
hypothalamicorneurovascularinjury
• Diffuseopticpathwayglioma
– Surgicalresectionisnotfeasible

30. Radiationtherapy
• Olderchildrenandthosewithprogressive disease
onChemotherapy,orrelapseafter completionof
chemotherapy
• Types
– Externalbeam(conformalorintensitymodulated)
– Stereotactic
– Protonbeam
Whenradiationtherapyisrequired,typical dosesrangefrom45
to60Gyin1.8-‐to2.0-‐Gyfractions

31. • Providesbetterlongtermtumorcontrol
• Progressionfree5yearratesarearound 90%

32. • Secondtumors
• Malignanttransformationof benigngliomas
• Cerebrovascularcomplications(postradiation
vascularocclusivedisorder)
• morecommoninchildrenwithNF1
• Morecommoninsuprasellargliomas
• Endocrinedysfunction
• Neurocognitivedysfunction
• Hypothalamicdysfunction
• NFpatientsareatahigherthanaveragerisk ofdeveloping
subsequentendocrinopathy, developmentalabnormalities,
neurocognitive dysfunction,andvasculopathy.