arachnoid_cysts tipo ppt.pdf

A h id C tA h id C tArachnoid CystsArachnoid CystsDean D. LinDean D. Lin

Department of NeurosurgeryDepartment of NeurosurgeryU i it f Fl idU i it f Fl idUniversity of FloridaUniversity of FloridaNovember 24, 2004November 24, 2004

OutlineOutlineOutlineOutline

EpidemiologyEpidemiologyPresentationPresentationLocationsLocationsImaging CharacteristicsImaging CharacteristicsImaging CharacteristicsImaging CharacteristicsPathologyPathologyTreatmentTreatment

DefinitionDefinitionDefinitionDefinition

“Benign, congenital, intra“Benign, congenital, intra--arachnoidal arachnoidal spacespace--occupying lesions filled with occupying lesions filled with

clear CSFclear CSF--like fluid”like fluid”

EpidemiologyEpidemiologyEpidemiologyEpidemiologyIncidence: 1% of intracranial mass lesionsIncidence: 1% of intracranial mass lesions

Age: 75% present during childhoodAge: 75% present during childhoodS i l 5S i l 5thth d d M Fd d M FSpinal: 5Spinal: 5thth decade, M=Fdecade, M=F

Gender: M:F = 3:1Gender: M:F = 3:1Gender: M:F 3:1Gender: M:F 3:1

Left side involved twice as frequentlyLeft side involved twice as frequentlyq yq y

Genetics: typically sporadic, nonGenetics: typically sporadic, non--syndromicsyndromic

EtiologyEtiologyEtiologyEtiology

Poorly UnderstoodPoorly UnderstoodPoorly UnderstoodPoorly Understood

“Old ” h th i “ litti ”“Old ” h th i “ litti ”“Older” hypothesis: “splitting” or “Older” hypothesis: “splitting” or diverticulum of developing arachnoiddiverticulum of developing arachnoid

“Newer” hypothesis: failure of frontal & “Newer” hypothesis: failure of frontal & ypyptemporal embryonic meninges to merge at temporal embryonic meninges to merge at sylvian fissuesylvian fissueyy

EtiologyEtiologyEtiologyEtiologyPotential mechanisms:Potential mechanisms:

Acti e secretion of CSFActi e secretion of CSF like fl idlike fl idActive secretion of CSFActive secretion of CSF--like fluid like fluid by cyst wallby cyst wall

Distention by CSF pulsationsDistention by CSF pulsations

Entrapment by oneEntrapment by one--way/ballway/ball--valve valve flowflow

Osmotic gradientOsmotic gradientOs ot c g ad e tOs ot c g ad e t

Spine: defect of Spine: defect of septum septum titiposticum posticum (thin membranous partition of (thin membranous partition of

the dorsal thoracic spinal cord)the dorsal thoracic spinal cord)

Associated AbnormalitiesAssociated AbnormalitiesAssociated AbnormalitiesAssociated Abnormalities

Temporal lobe hypoplasiaTemporal lobe hypoplasiaTemporal lobe hypoplasiaTemporal lobe hypoplasia

HematomaHematoma –– subdural and intrasubdural and intra--cysticcysticHematoma Hematoma subdural and intrasubdural and intra--cysticcysticTearing of bridging veinsTearing of bridging veinsAssociated with mild head injuryAssociated with mild head injuryj yj y

MacrocephalyMacrocephalyMacrocephalyMacrocephaly

Spinal arachnoid cysts: kyphoscoliosisSpinal arachnoid cysts: kyphoscoliosisSpinal arachnoid cysts: kyphoscoliosisSpinal arachnoid cysts: kyphoscoliosis

PresentationPresentationPresentationPresentationNatural history Natural history –– unclearunclearyy

Most cranial cysts do not enlargeMost cranial cysts do not enlargeSpinal cysts frequently enlargeSpinal cysts frequently enlarge

6060--80% symptomatic80% symptomatic

Most common symptoms:Most common symptoms:HeadacheHeadacheHeadacheHeadacheSeizureSeizureFocal deficitsFocal deficits

PresentationPresentationPresentationPresentationOther signs/symptoms:Other signs/symptoms:g y pg y p

Protrusion of skull, widen spinal canalProtrusion of skull, widen spinal canal

SuprasellarSuprasellarSuprasellarSuprasellarVisual impairmentVisual impairmentEndocrinopathies (up to 60% suprasellar cysts)Endocrinopathies (up to 60% suprasellar cysts)“Bobble“Bobble--head doll syndrome”head doll syndrome”

22--3/second AP bobbing3/second AP bobbing

Spine Spine –– pain/cord compressionpain/cord compressionIntermittent claudication, spasticityIntermittent claudication, spasticityWorse with ValsalvaWorse with ValsalvaWorse with ValsalvaWorse with Valsalva

LocationsLocationsLocationsLocations

LocationsLocations

Sylvian fissue/middle fossaSylvian fissue/middle fossa 49%49%yyCerebellopontine angleCerebellopontine angle 11%11%Quadrigeminal cisternQuadrigeminal cistern 10%10%Quadrigeminal cisternQuadrigeminal cistern 10%10%VermianVermian 9%9%Sellar/suprasellarSellar/suprasellar 9%9%InterhemisphericInterhemispheric 9%9%

• Spine - most commonly in Thoracic region• Typically dorsalTypically dorsal• Extra- or intra-dural

Radiographic AppearanceRadiographic AppearanceRadiographic AppearanceRadiographic Appearance

CT:CT: wellwell--demarcated cystic massdemarcated cystic massCT:CT: wellwell demarcated cystic massdemarcated cystic massExtraExtra--axial axial –– exerts mass effectexerts mass effectCSFCSF like densitylike densityCSFCSF--like densitylike densityNo enhancementNo enhancementE pands/remodels boneE pands/remodels boneExpands/remodels boneExpands/remodels boneIntracystic hemorrhage Intracystic hemorrhage –– hyperdense (rare)hyperdense (rare)

CTA:CTA: MCA vessels posteriorly displacedMCA vessels posteriorly displaced


MRI:MRI: wellwell--demarcated cysticdemarcated cysticMRI:MRI: wellwell demarcated, cysticdemarcated, cysticT1WI and T2WI: isointense to CSFT1WI and T2WI: isointense to CSFNo enhancementNo enhancementNo enhancementNo enhancement

Fl iFl i S dS dFlair:Flair: SuppressedSuppressed

DiffusionDiffusion--weighted:weighted: No restrictionNo restriction


CTCT--MyelogramMyelogramCTCT MyelogramMyelogramMay or may not communicate with May or may not communicate with subarachnoid spacesubarachnoid spacesubarachnoid spacesubarachnoid spaceLargely replaced by MRILargely replaced by MRIMore important for spinal arachnoid cystsMore important for spinal arachnoid cystsMore important for spinal arachnoid cystsMore important for spinal arachnoid cysts

Galassi ClassificationGalassi ClassificationMiddle fossa arachnoid cystsMiddle fossa arachnoid cysts

Type I:Type I: small, lenticular; small, lenticular; ypyp , ;, ;located at temporal pole;located at temporal pole;

Communicates with subarachnoid Communicates with subarachnoid spacespace

Type II:Type II: involves anterior and involves anterior and intermediate segments of intermediate segments of Sylvian fissue; quadrangularSylvian fissue; quadrangularSylvian fissue; quadrangularSylvian fissue; quadrangular

Partially communicates with Partially communicates with subarachnoid spacesubarachnoid space

Type III:Type III: entire Sylvian fissue, entire Sylvian fissue, bony expansion of middle bony expansion of middle fossa; mass effectfossa; mass effect

Mi i l i ti ithMi i l i ti ithMinimal communication with Minimal communication with subarachnoid spacesubarachnoid spaceMarked shiftMarked shift

Arachnoid CystsArachnoid CystsImaging Imaging –– Middle FossaMiddle Fossa

Elevation of lesser sphenoid wing, thinning of squamous bone

Frontal displacement of greater wing


Type IType I

• Rarely treated


Type I


Type II Treat if symptomatic


Type IIIType IIIComplete re-expansion frequently not achieved

Arachnoid CystsArachnoid CystsImaging Imaging -- CTCT

Arachnoid CystsArachnoid CystsArachnoid CystsArachnoid CystsImaging Imaging –– Sellar/suprasellarSellar/suprasellar

Frequently present with obstructive hydrocephalus, visual impairment, and endocrinopathies

Arachnoid CystsArachnoid CystsImaging Imaging –– Cerebellopontine angleCerebellopontine angle

Arachnoid CystsArachnoid CystsImaging Imaging –– Quadrigeminal and ClivalQuadrigeminal and Clival

Obstructive hydrocephalus

Arachnoid CystsArachnoid CystsImaging Imaging –– VermianVermian

Arachnoid CystsArachnoid CystsImaging Imaging –– Posterior fossaPosterior fossa

Arachnoid CystsArachnoid CystsImaging Imaging –– hemorrhagichemorrhagic

• Intracystic hemorrhage • Acute intracystic hemorrhage y gand subdural hematoma

y gwith fluid-fluid level

S i l A h id C tS i l A h id C tSpinal Arachnoid CystsSpinal Arachnoid Cysts

Arachnoid/Meningeal CystsArachnoid/Meningeal CystsSpine Classification Spine Classification –– Nabors et al., 1988Nabors et al., 1988

Type I: Extradural: No nerve rootsType I: Extradural: No nerve rootsType I: Extradural: No nerve rootsType I: Extradural: No nerve rootsType IA: extradural arachnoid cystType IA: extradural arachnoid cystType IB: sacral meningoceleType IB: sacral meningoceleFib li iFib li iFibrous liningFibrous lining

Type II: Extradural: Roots involvedType II: Extradural: Roots involvedType II: Extradural: Roots involvedType II: Extradural: Roots involvedTarlov cystsTarlov cystsFibrous liningFibrous lining

Type III: Intradural arachnoid cystsType III: Intradural arachnoid cysts+ arachnoid lining+ arachnoid liningggDifferent T2 signal sometimes (no pulsations)Different T2 signal sometimes (no pulsations)

Arachnoid CystsArachnoid CystsSpineSpine

Intradural versus Extradural: EtiologiesIntradural versus Extradural: EtiologiesIntradural versus Extradural: EtiologiesIntradural versus Extradural: Etiologies

Intradural:Intradural: arachnoid diverticulum or adhesion orarachnoid diverticulum or adhesion orIntradural:Intradural: arachnoid diverticulum or adhesion or arachnoid diverticulum or adhesion or trabecular proliferation, either congenital or secondary trabecular proliferation, either congenital or secondary to trauma/infectionto trauma/infection

Extradural:Extradural: associated with a dural defect; ballassociated with a dural defect; ball--valve valve effect causes enlargementeffect causes enlargementeffect causes enlargementeffect causes enlargement

Workup includes MRI followed by CTWorkup includes MRI followed by CT--myelogrammyelogramp yp y y gy g

Arachnoid CystsArachnoid CystsI iI i S iS iImaging Imaging –– SpineSpine

Arachnoid CystsArachnoid CystsImaging Imaging –– SpineSpine

Diff ti l Di iDiff ti l Di iDifferential DiagnosisDifferential Diagnosis

Arachnoid CystsArachnoid CystsImaging Imaging –– Differential DiagnosisDifferential Diagnosis

Differential includes any cystic tumorsDifferential includes any cystic tumorsJPAsJPAsCraniopharyngiomasCraniopharyngiomasHemangioblastomaHemangioblastoma

Also any nonAlso any non--neoplastic cystneoplastic cystAlso any nonAlso any non neoplastic cystneoplastic cystPorencephalic cystPorencephalic cystNeurenteric cystNeurenteric cystNeurenteric cystNeurenteric cyst


Primary differential: epidermoid cystsPrimary differential: epidermoid cystsPrimary differential: epidermoid cystsPrimary differential: epidermoid cysts

Epidermoid CystsEpidermoid CystsImaging Imaging –– Differential DiagnosisDifferential Diagnosis

Arachnoid vs Epidermoid Cysts Arachnoid vs Epidermoid Cysts Differentiate with FLAIR and DWIDifferentiate with FLAIR and DWI

Epidermoid Arachnoid cystp y


Arachnoid cyst versus

mega cisterna magna

• ACs have mass effect

AC Mega CM

PathologyPathologyPathologyPathology

Gross:Gross: thin, thin, translucent cyst wall translucent cyst wall filled with CSFfilled with CSF

PathologyPathologyPathologyPathology

Microscopic:Microscopic: cystcystMicroscopic:Microscopic: cyst cyst lined by flattened lined by flattened arachnoid cellsarachnoid cells

Sometimes with Sometimes with proliferated trabeculaeproliferated trabeculae

TreatmentTreatmentTreatmentTreatment

Controversial:Controversial:

Shunting versus excision/fenestrationShunting versus excision/fenestration

TreatmentTreatmentShuntingShunting

Pros:Pros:Pros:Pros:easy to performeasy to performimmediate cyst decompressionimmediate cyst decompression

Cons:Cons:Frequently need to shunt both ventricle and cystFrequently need to shunt both ventricle and cystInfectionInfectionRecurrenceRecurrenceRecurrenceRecurrenceVisualization Visualization –– bridging veinsbridging veinsSlitSlit--cyst syndrome (symptoms of elevated ICP but cyst syndrome (symptoms of elevated ICP but decompressed cyst)decompressed cyst)

TreatmentTreatmentExcision/fenestrationExcision/fenestration

Goal: Goal: decompression with shuntdecompression with shunt--independenceindependencepp pp

Pros:Pros:R l ti lR l ti lRelatively easyRelatively easyNo foreign material implantedNo foreign material implantedExcellent visualizationExcellent visualization

Cons:Cons:Some increased recurrence rate depending onSome increased recurrence rate depending onSome increased recurrence rate depending on Some increased recurrence rate depending on techniques (scarring, adhesions)techniques (scarring, adhesions)May still require shuntingMay still require shunting


Techniques:Techniques:Techniques:Techniques:Open craniotomyOpen craniotomy

Endoscopic fenestrationEndoscopic fenestrationM t ff ti f ll t ithM t ff ti f ll t ithMost effective for suprasellar cysts, esp. with Most effective for suprasellar cysts, esp. with opening of lamina terminalisopening of lamina terminalis

Keyhole craniotomyKeyhole craniotomyRecently shown to be very effective: 80Recently shown to be very effective: 80--95%95%Recently shown to be very effective: 80Recently shown to be very effective: 80--95% 95% success rate with middle fossa cystssuccess rate with middle fossa cysts


Pre-op Post-op

TreatmentTreatmentSpinal arachnoid cystsSpinal arachnoid cysts

Laminectomy and excisionLaminectomy and excision

Closure of dural defect with extradural Closure of dural defect with extradural cystscystscystscysts

May also require shunting (intradural)May also require shunting (intradural)

H Th k i iH Th k i iHappy ThanksgivingHappy Thanksgiving

arachnoid_cysts tipo ppt.pdf

Documents