Title ［症例報告］Posterior Reversible Encephalopathy Syndrome: Typical and AtyDical Findings on MR Imaging

Author(s) Yamashiro, Tsuneo; Kamiya,Hisashi; Unten, Shinobu; Iida,Gyo; Murayama, Sadayuki

Citation 琉球医学会誌 = Ryukyu Medical Journal, 26(3・4): 167-171

Issue Date 2007

URL http://hdl.handle.net/20.500.12001/1909

Rights 琉球医学会

旦γ的γⅡ肋d．よ，2釈凰4167～1円，2007

Posterior Reversible Encephalopathy Syndrome：

Typical and AtyDical Findings on MRImaging

Tsuneo Yamashiro，MD，HisashiKamlya，MD，Shinobu UntenMD，GyoIida，MD and SadayukiMurayama，MD，PhD

か甲αr如e柁t q／月αdiobgy GrαdはαねScゐ00Jq／Medical Sciense　UniversityoftheRyukUS．

ごりrJ′ノJ′1川、．＼－ノバ／J／／J′1川■イい、／舶／J′JJHJ H仕J圧〃・丁．・／′り〝′／J

（Received on May29，2007，aCCePted onJune，22，2007）

ABSTRACT

We report three cases of posterior reversible encephalopathy syndrome（PRES），

CauSed by eclampsla Or Chemotherapeutic drugs．In allthr・ee CaSeS，nOt Only the occIP1－

tal and／or parietallobes but also the brain stem，Cerebellum，basal ganglia and other

lobes were widelyinvolved on magnetic resonance（MR）imaging．In two cases，abnor一

mal slgnals disappeared completely on follow－uP MRimaglng．However，Partialirre－

VerSible change persistedin the third case，Which showed atypicalhyperintense slgnals

on theinitialdiffusion－Weighted（DW）images．We emphasize that PRESis not always

COmPletely reversible and DWimaglng may be helpfulin distinguishinglrreVerSiblele－

Sions from typical，reVerSiblelesions．f抄uhyuMbd．Jl，26（3，4）167～171，2007

Keywords：POSterior reversible encephalopathy syndrome，magnetic resonanceimaglng，

diffusion－Weightedimaglng，eClampsia，hypersensitive encephalopathy

INTRODUCTION

Posteriorreversibleencephalopathy syndrome

（PRES），also　known as reversible posteriorleukoencephalopathy syndr・Ome，is defined as a

neurologic disorder demonstrating characteristic

radiologlCal abnormalities found mainlyin the

OCCipital and parietallobes and other posterior

circulationterTitories．Severalconditionsand medi－

Cationshave been reported to cause PRES；hyper－

SenSitive encephalopathy，Chemotherapeutic or

immunosuppressive dr・ugS，eClampsla－PreeClampsla，

andrenalfailurearefrequentlydescribedl‾5）．Mag－

neticresonance（MR）imaginghasbeenreportedas

the best modality to demonstrateinvoIved areas，

usually resultingin hyperintense slgnals on T2－

Weighted or fluid－attenuatedinversion recovery

（FLAIR）images，andisointense signals on diffuT

Sion－Weighted（DW）images，reflecting reversiblevasogenicedema2・5）．Althoughtheterm PRESim－Plies that theinvolvedlesions are r・eversible，un－

usually advanced cases may developirreversible

Changes that show up as hyperintense slgnals on

167

DWimages．Additionally，SeVeralstudieshavere－

portedthatPRESinvoIves anteriorcirculationter－

ritories as wellas posterior territories2・6．11）

Here，WerePOr・tthreecasesofPRES．Twoof

the cases showed multiplelesionsin the anterior

and posteriorterritories and achieved complete re－

COVery．Inthethird case，Onthe otherhand，Only

the occipital and parietallobes wereinvolved on

initial MRimaglng．However，follow－uP MRim－

aglng reVealed partial，irreversible changesin ac－

COrdance with the hyperintense slgnals on the

initial DWimages．This report aims to supple－

mentpreviousar・ticlesofPRES，mainlybyitsdis－

tribution on MRimaglng and the effectiveness of

DWimaglng tO predictirreversible changes．

CASE REPORT

Casel

A39－year－01dwomanwasundergolngaSChed－

uled cesarean section for twin．When around the

time of the operation，her blood pressure elevated

to160／100mmHg and she complained of a mild

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Fig．1Casel（39－year－01d woman with eclampsia）

A，B）FLAIRimages．Many hyperintense areas are

Observedbilaterallylnthebasalganglia，OCCipitallobes，

SPlenium of corpus callosum，1eft temporallobe，and

SeVeralgyrlOf the frontallobes．No abnormalslgnal

is detected on DWimages（not shown）．

C）Afollow－uP FLAIRimage shows complete recov－

ery of abnormalsignals（one monthlater）．

headache．Nine hours after delivery，She suddenly

exper・ienced a general convulsion thatlasted one

minuteandresolvedspontaneously．Onehourlater，

asecondconvulsionoccurredandpersistedforthree

minutes．Thepatientreceivedanticonvulsant drugs

and was admittedinto theintensive care unit．No

Other abnormalneurologic findings were detected．

Blood examination revealed a declined platelet，COunt

Of6．3×104／ul，anelevatedaspartateaminotransferase

level of　233　mg／dl，and an elevated alanine

aminotransferaselevel of153mg／dl，Which were

COnSistentwith HELLP syndrome．Brain MRim－

aglng WaS Performed the followlng day and dem－

OnStrated sever・al hyperintense　areaS On FLAIR

images found mainlyin the basal ganglia，brain

Stem，right cerebellum，and parieto－OCCipitallobes（Fig．1A）．Inaddition，Smallcorticalandsubcortical

lesions were also revealedin the frontallobes

（Fig．1B）．Noobvioushyperintensesignalwas ob－

SerVed onDWimages．After receivlng medication

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Fig．2Case2（47－yearrOldwomanundergoingchemother－

apy for adrenalcancer）

A，B）Initial T2－Weightedimages．Relativelylarge，

indistinct hyperintense areas are observedintheright

Cerebellum and rightoccipitallobes（arrow）．Some ab－

normal slgnals are demonstratedin t，heleft cerebe1－

1um，basal ganglia and thalami．DWimages do not

revealabnormalsignals（not shown）．

C）The right cerebellarlesion disappears completely

OnafollowrupFLAIRimage（two weekslater）．Other

lesions also showcomplete recovery．

for brain edema，She maintained free of seizure

andherabnormallaboratory valuesimproved．She

WaSdischarged8dayspost－Sur・gery，andfollow－uP

MRimaglng One mOnthlater demonstrated com－

plete recovery of the abnormalsignals（Fig．1C）．

Case2

A　47－yearTOld woman，Who was previously

diagnosed with multiplelung metastases ofleft

adrenalcancer，WaS reCeivlng Chemotherapy using

CISPlatine，etOPOSide and doxorubicin．Her blood

PreSSuregraduallyelevatedfrom140／80mmHgto

170／100mmHg during the chemotherapy．On the

25th day of the series，She suddenly demonstrated

generalized tonic－Clonic seizur・e，Which r・eSOIved

SPOntaneOuSlyln aPPrOXimately one minute．Her

bloodpressure roseto220／120mmHgatthe same

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Fig．3Case3（27－year－01d woman undergoing chemo－

therapy for Ewing sarcoma）

A）Aninitial FLAIRimage shows bilateral，1arge

hyperintenselesionsin the parietallobes．

B）The parietallesionsdemonstrate hyperintense sig－

nalsonaninitialDWimageofthesamelevel（arrows）．

C）Afollow－upFLAIRimage（onemonthlater）shows

indistinct，irreversible degenerationsin the parietal

lobes（arrows）．Otherlesionsintheparietaland occipi－

tallobes recover completely．

time．She had a second seizure on the same day，

andreceived anintravenous anticonvulsant as well

asacalcium－blockerto controlherbloodpressure．

Physical examination did not reveal abnormal

neurologic findings．Br・ain MRimaglng WaS Per－

formedthe followlngday．On T2－Weightedimages（Fig．2A，2B），Small hyperintenselesions were

Prlmarily observedin theoccipitallobesandcere－

bellum．Tinylesions were also seenin the basal

ganglia and thalami．No abnormalslgnaling was

detected on DWimages．Afterreceivingthe medi－

Cation，the patient did not experience any further

Seizuresandfollow－uPMRimaglngtWOWeekslater・

revealedcompletedisappearanCeOfthelesions with－

Out degeneration（Fig．2C）．

Case3

A27－year－01dwomanwitharightfemoralEwing

SarCOma WaS reCeiving preoperative chemotherapy

169

using cyclophosphamide，　doxorubicin and

vincristine．OnthelOthdayoftheseries，Shecom－

Plained of sudden narrowlng Of her visual field．

Physical examination revealed right hemianoplabut no other neurologlC abnormalities．Her blood

PreSSure WaS Slightly elevated at150／100mmHg．

Brain MRimaglng On the same day showed obvi－

OuS hyperintense areas spreading bilaterallyin

theocclpltalandparietallobesonT2－Weightedim－ages and FLAIRimages，Which contained both

COrtical and subcorticalinvolvements（Fig．3A）．

On DWimages，Partialhyperintense slgnals were

Seenin the parietallobes（Fig．3B），Which were

atypicalas PRES．Thepatient receivedmedication

forbrainedemaandhypertension，andherhemianopla

resoIved completely within one week．Follow－uP

MRimaglng WaS Performed approximately one

monthlater．Althoughalmostallabnormalslgnals

had disappeared，Smallirreversible degenerations

Were Observedin the parietallobes，Which were

COnSistentwiththehyperintenseareaS SeenOnthe

initialDWimages（Fig．3C）．However，thepatients

didnotcomplainofanypersistentvisualdisorders．

DISCUSSION

PRESwasorlglnallytermed“reversibleposterior

leukoencephalopathy syndrome”by Hinchey et al．

in19961）．Theyemphasizedthesimilarityofabnor一

mal findings on CT and MRimaglng for several

COnditions，including hypertensive encephalopathy，

eclampsla，r・enal failur・e，and complications of

immunosuppressive drug therapy（cyclosporine，

tacrolimus）．At first，it was thought that onlywhite matter wasinvoIved；thus，the term“1euko

encephalopathy”was fr・equently used．However，

SeVeralsubsequentreports，Particularlythose using

FLAIRsequences，Clarifiedthatcorticalgraymat－

ter，aS Well as subcortical white matter，WaS also

invoIved5，10）．Therefore，“PRES”has recently be－

come the more favored term．In addition to such

Classicalconditions，manydiseasesand drugs have

beenreportedtocausePRES，includingautoimmune

diseases such as systemiclupus erythematosus or

rheumatoidarthritis，thromboticthrombocytopenic

purpura，interferon－alpha，and chemotherapeutic drugs

such as cISPlatin，CyClophosphamide，Vincristinel，2，5即2・13）

PRES typically occurs followlng an elevation of

blood pressure，aS Our rePOrt Showed．However，

SeVeralcases have been reported that do not show

170 Posterior Reversible Encephalopathy Syndrome

hypertensionaround the occurrence2▼4・10）．Insome

exceptional patients，reCurrent ePisodes of PRES

have been repor・ted12）．

PRES presents clinically with headache，SeiT

ZureS，Visual changes（cortical blindness），altered

mental status，and occasionally focal neur0loglC

slgnSl，2，6，9）．AlthoughitstrueetiologylSStillun－Clear，ithas been suggestedthatPRESis actually

temporaryvasogenicedemacausedbylossofcerebral

VaSCular autoregulationin theinvoIved brain，and

not cytotoxic edema orinfarction1，5，日0）．This the－

OryhasbeensupportedbypathologlCrePOrtSdem－

OnStratingonlyinterstitialedema，microhemorrhages，

and fibrinoid necrosis within the arteriole wallsin

invoIvedlesionsl・5）

PRESischaracter・izedbythedistribution seen

OnMRimaglng；bilateralandrelativelysymmetric

hyperintenselesions mainlyintheparieto－OCCipital

reglOnS On T2－Weighted or FLAIRimagesl‾6）．This

CharaCteristic distr・ibution has been explained as

VaSOgenicedemathatoccurseasilyintheposterior

Cerebralarter・yter・ritories．Thesameconditionoften

OCCurSin other posterior circulation territories，

including the brain stem and cerebelluml‾5・14・15）

However，aS tWOOfourformercasesshowed，PRES

Can OCCurin thearea supplied by the anterior or

middle cerebral arteries，andis usually accompa－

nied by posteriorinvolvementl，9・10）．Furthermore，

SOmeeXCePtionalcaseshavedemonstrated onlylS0－

1atedanteriorlesionswithoutposteriorinvoIvement8）．

Thus，althoughtheoccipitalandparietallobesand

theinfratentorial br・ain are the areas most fre－

quentlylnVOIvedinPRES，it should be takeninto

consideration that，eVenanteriorcirculationterrito－

ries，includingthebasalganglia，thalami，andfron－

talor temporallobes，Can beinvoIved．

AnotherimaglngfeatureofPRESisreversibil－

ity．ClassicalPRESdemonstrateshyperintenseslg－

nalsonT2－WeightedandFLAIRimages，andnormalOr・slightlydecreased／incr・eased signalson DWim－

ages，Which suggest the potential for reversible

VaSOgenic edema．These abnormalslgnals on T2－

Weighted and FLAIRimages usually disappearquickly within a few weeksif blood pr・essureis

PrOPerly controlled or other offending factors are

removedl，2，5，9110）．on the other hand，aCute brain

infarction or cytotoxic edema appear as apparent

hyperintense slgnals on DWimages and resultin

irreversibledegeneration．Thus，nOrmalorinterme－

diate DW slgnals have been thought to be an

essential finding for the diagnosis of PRES2，9）

However，SeVeralrecentreportshaveclarifiedthat

atypical hyperintense slgnals on DWimages are

relatively commonandmayaccountforupto27％

ofallPRESpatients2，6，9・10・11）．Inourpresentreport，

One Patient demonstrated hyperintenseareaS On

initialDWimages，Whichlaterturnedintopartial，

irreversible changes on followTuP MRimaglng．

Given the fact that patients with abnormal

hyperintense DW signals persistedirrever・Sible de一

generation（infarction）onfollow－uP MRimaging，

PRES should be consideredpotentiallylrTeVerSible

orcytotoxicandrequlre Carefulmanagement7）．

AlthoughDWimaglngisthoughttobeause－fulsequencefordiagnoslnglrreVerSiblechangesin

PRES，SeVeralexceptionalcaseshavebeenreported

that showed reversiblelesions with hyperintense

DWsignals2，9・10，15）．ThisphenomenonisknownasT2Shine through，Whichis caused byincreased T2slgnalsaffectingDWsignals2，9）．Inthesecases，aP－

parent diffusion coefficient（ADC）mapsgive fur－

therinformation onwhether thelesionsare truly

reversible or not．Unfortunately，ADC mapplng

WaS nOtaVailableatourinstitutionduringthetime

Of study．We can currently evaluate thepatients

WithacombinationofDWimaglngandADCmap－

Plng，thus，furtherresearchwillbeperformedwith

mOre aCCuraCy．

Inconclusion，PRES caninvolvenot onlythe

parietaland／or occipitallobes，but also the brain

Stem，Cerebellum，basal ganglia，thalamus，and

frontalor tempor・allobes，aS Showninour・CaSeS．

AlthoughDWsignalsareusuallynormalforlesionsOf reversible vasogenic edema，hyperintense DW

Slgnals may be seeninadvanced casesthatpersist

toirreversiblechanges．Physiciansshouldbeawar・e

thatinvoIved areas are not always reversiblein

PRES and DWimaglng Can be helpfulfor distin一

guishinglrreVerSible changes from true reVerSible

lesions．

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