Hemianopia and visual neglect: a question of balance?

Patients with visual neglect fail to orient or attend predominately to contralesional space and this is thought to result from disorders involving various ... Skiptomaincontent YouarehereHome Archive Volume67, Issue5 Hemianopiaandvisualneglect:aquestionofbalance? Emailalerts ArticleText Articlemenu ArticleText Articleinfo CitationTools Share RapidResponses Articlemetrics Alerts PDF Editorialcommentary Hemianopiaandvisualneglect:aquestionofbalance?Free PWHALLIGANDepartmentofExperimentalPsychology,OxfordOX14XD,UK.Telephone00441865790363or240321;fax00441865200185;emailpeter.halligan{at}clinical-neurology.oxford.ac.uk http://dx.doi.org/10.1136/jnnp.67.5.565 StatisticsfromAltmetric.com Visualneglectandvisualfielddeficitscommonlyco-occurafterunilateralbraindamagesuchasstroke.Theconditions,however,arerecognisedasoperationallyandconceptuallydistinct.Avisualfielddefectdescribessensorylossrestrictedtothevisualfieldandarisesfromdamagetotheprimaryvisualpathwayslinkingoptictractandstriatecortex.Patientswithvisualneglectfailtoorientorattendpredominatelytocontralesionalspaceandthisisthoughttoresultfromdisordersinvolvingvariousdifferentattentionalsystems.Visualfieldassessmenttypicallyemploysconfrontationandrequiresfixationwhereasvisualneglectisnormallyassessedinfreevisionandtypicallyequiresamanualresponse.Although,itispossibletoconfoundvisualfielddefectsandvisualneglect,1itisgenerallyacceptedthattheconditionsrepresentfunctionallyunrelateddisordersthatdifferintermsoflesionlocation,eyemovements,prognosis,andpatternsofrecovery.Inaddition,theconditionshavebeenshowntodoubledissociate.2 Becausebothconditionsultimatelyinvolveimpairmentstovisualprocessing,itisnotclearhowpatientswithvisualfielddefects(butwithoutvisualneglect)performonneglecttestssuchaslinebisection.TheanswerwasoriginallydescribedinGermanclinicalreportsattheturnofthecentury.3 4Thesereports,recentlyconfirmedbyBartonandBlack5foundthatrightbraindamagedpatientswithleftvisualfielddefectsshowedreliablecontralesionaldisplacement(totheleft)onlinebisection,whereasrightbraindamagedpatientswithneglectshowedtypicalipsilesionaldisplacement(totheright).Giventhesereportsofopposingdirectionaldisplacements,FerberandKarnath6(thisissue,pp572–8)hypothesisedthatthepresenceofavisualfielddefectinpatientswithvisualneglectcouldacttoreduceorevencancelthetraditionalrightwarddeviationfound.SuchapredictionifconfirmedwouldconstituteanovelformoffunctionalfacilitationnotunlikethatreportedbySprague7incats.The“Spragueeffect”describesthestrikingbehaviouralfindinginwhichtheeffectsofavisualfielddeficitafterarighthemisphericlesionaresubsequentlyabolishedbyasecondlesioninthelefthemisphere.Clinicalanaloguesofthiseffectarecomparativelyrare.8Usingasimpletestthatrequiredrightbraindamagedpatientstoindicateverballythesubjectivestraightahead(SSA)position,FerberandKarnathconvincinglyshowthattheinteractionofthesetwoconditionsinpatientswithcircumscribedlesionscanproducesignificantlyreduceddeviationswhencomparedwithpatientswithvisualneglectalone.UnlikeSprague’sfindingtheirresultssuggestthattheinteractionoftwofunctionallyunrelatedbutsimultaneouslypresentdeficitswithinthesamehemisphereacttoneutraliseopposingdeviationsonthistask.Itwouldbemisleadingtoconcludeonthebasisofthesefindings,however,thattheeffectsofvisualfielddefectsinthesepatientshadabolishedneglect.Theresultsoftheclinicalcancellationtaskinthesamestudyclearlyshowthatpatientswithvisualneglectandhemianopiaperformworseonthecontralesionalsideofthepagethatthosewithneglectalone.Unfortunatelytheperformanceonlinebisectionisnotreported.Therefore,whereastheeffectsofthevisualfielddefectsmayreducethedirectionalorientationofneglect’srightwardbiasonthesubjectivestraightahead(SSA),itdoesnotgeneralisetomoretraditionalclinicaltasksandmaydependonthenatureanddemandsofthetasksinvolved.ApreviousstudybyHalliganetal,2usingsixclinicaltestsofvisuospatialneglectfailedtofindasignificantdifferencebetweenvisualneglectpatientswithandwithoutvisualfielddefects.Furthermore,thesamestudydidnotfindanyclinicalevidenceofanopposingdirectionalbiasinpatientswithvisualfielddefectsonly.CautionisalsorequiredininterpretingthefindingsasitnotclearthatdisplacementontheSSAisnecessarilytheresultofvisualneglect.8Notwithstandingsuchreservations,thestudyprovidesacompellingandoriginalillustrationofhow“paradoxicalfunctionalfacilitation”canmotivatetheoreticalinsightsintothebehaviouraleffectsoftraditionallydistinctdisorders.9 References↵ KooistraCA,HeilmanKM(1989)Hemispatialvisualinattentionmasqueradingashemianopia.Neurology39:1125–1127.OpenUrlAbstract/FREEFullText ↵ HalliganPW,MarshallJC,WadeDT(1990)Dovisualfielddeficitsexacerbatevisuo-spatialneglect?JNeurolNeurosurgPsychiatry53:487–491.OpenUrlAbstract/FREEFullText ↵ AxenfeldD(1894)EineeinfacheMethodeHemianopsiezuconstatiren.NeurolCentralbl,pp437–439. ↵ LiepmannH,KalmusE(1900)UebereineAugenmastorungbeiHemianopikern.BerlinKlinWochenschr38:838–842.OpenUrl ↵ BartonJJ,BlackSE(1998)Linebisectioninheminaopia.JNeurolNeurosurgPsychiatry64:660–662.OpenUrlAbstract/FREEFullText ↵ FerberS,KarnathH-O(1999)Parietalandoccipitallobecontributionstoperceptionofstraightaheadorientation.JNeurolNeursurgPsychiatry67:572–578.OpenUrlAbstract/FREEFullText ↵ SpragueJM(1966)Interactionofcortexandsuperiorcolliculusinmediationofvisualyguidedbehaviourinthecat.Science153:1544–1547.OpenUrlAbstract/FREEFullText ↵ ChokronS,BartolomeoP(1997)Patternsofdissociationbetweenlefthemineglectanddeviationofegocentricreference.Neuropsychologia11:1503–1508. ↵ KapurN(1996)Paradoxicalfunctionalfacilitationinbrain:behaviourresearch.Brain119:1775–1790.OpenUrlAbstract/FREEFullText RequestPermissions IfyouwishtoreuseanyorallofthisarticlepleaseusethelinkbelowwhichwilltakeyoutotheCopyrightClearanceCenter’sRightsLinkservice.Youwillbeabletogetaquickpriceandinstantpermissiontoreusethecontentinmanydifferentways. Copyrightinformation: JournalofNeurology,Neurosurgery,andPsychiatry LinkedArticles PaperParietalandoccipitallobecontributionstoperceptionofstraightaheadorientation SusanneFerber Hans-OttoKarnath JournalofNeurology,Neurosurgery&Psychiatry1999;67572-578PublishedOnlineFirst:01Nov1999.doi:10.1136/jnnp.67.5.572 ReadthefulltextordownloadthePDF: Subscribe Login LoginviaInstitutionLoginviaOpenAthens Loginusingyourusernameandpassword ForpersonalaccountsORmanagersofinstitutionalaccounts Username* Password* Forgotyourlogindetails?Registeranewaccount?Forgotyourusernameorpassword?