简介：ObjectiveSinceHelms'successfulbilateralcochlearimplantationwithgoodresultsin1996,therehavebeenincreasingnumberofreportsonbilateralcochlearimplantation.Mostseconddevicehavebeenimplantatedwithinoneyearafterthefirst.Consideringeffectsoflongtimeauditorydeprivation,itisnotclearwhetheradelayedsecondcochlearimplantservestoaddadditionalbenefitsandhowitmayinteractwithcentralnervoussystemplasticity.MethodsThreecaseswhoreceiveddelayedsecondcochlearimplantsatPeople'sHospitalofPekingUniversityfrom2002to2005werereviewed.Theintervalbetweenthefirstandsecondimplantswaslongerthan2yearsinallthreepatients.Soundperception,andunilateral/bilateralspeechdiscriminationinquietandnoisewereevaluated.Inaddition,GAPdetectiontestwasconductedinonepatient.ResultsInonecase,havingbothimplantsonprovidedimprovedperformancecomparedtousingonlyoneimplantbothinquietandnoise.Presumablyduetovisualinterferencefromlip-readingorshortintervalbetweensecondimplantandtesting,onepatientshowednoimprovementfromusingthesecondimplanteitherinquietornoise,whilethelastcasedemonstratedadditionalbenefitsfromthesecondimplantonlyinquiet.Inallthreepatients,performanceinrecognizingthefourtonesinMandarinwassuperioroverwordrecognition.ConclusionsConsiderableplasticityinthecerebralauditorycenterispreserved,despitelongacousticdeprivationinsomechildrenwhohavereceivedunilateralcochlearimplant.Delayedsecondimplantscanresultinsignificantimprovementsinsomeofthesechildren.Visualinterferencefromlip-readingmaybeanobstacleduringretraining.ThebetterrecognitionoftonesintheMandarinlanguagemayrepresentadifferentsounddiscriminationmechanismintheauditorysystem,althoughitmayalsoberelatedtothesignalprocessingmechanismsoftheimplantused(MED-ELCOMBI40+).