Newborn neurologic examination

describe the newborn examination and 2) briefly describe the most common neurologic problems seen in the newborn population. One of the most dreaded calls for the adult neurology resident is the consult from the neonatal in-tensive care unit (ICU). Faced with the morass of tubes and monitors underneath which lies a tiny infant,


Texto en PDF


NewbornneurologicexaminationMicheleYang,MD
hisisthefirstarticleinase-riesdescribingtheessentialsofthepediatricneurologicex-amination.Theserieswilladdresstheneurologicexaminationatdif-ferentdevelopmentalstagesfromtheneonatetotheteenageyears.Thegoalsofthearticleareto1)describethenewbornexaminationand2)brieflydescribethemostcommonneurologicproblemsseeninthenewbornpopulation.
ment(suchascrying).Hearing(CNVIII)canbetestedwithabell,keepinginmindthataringingbellwithinanisolettecanbequiteloudandgenerate90dB.Thenewbornmayhaveaverysubtleresponsetoauditorystimulusandrespondwithonlyablink.TotestCNV,VII,andXII,thenewborncanbeobservedsuckingonapacifier.ThiscanalsobeusedtoevaluateCNIXandX,whicharetestedwhenthebabyswallows.The28-weekinfantcansuckandswallowbutthesyn-chronyofbreathingandfeedingisnotwelldeveloped.Asthebrain-stemmatures,coordinationim-provesbythe32ndto34thweek.Palpationofthesternocleidomas-toid(CNXI)maybedifficultinthenewborn,butmaybefacilitatedbyextendingtheheadonthesideofthebedwiththeinfantinasupineposition.Nowthebulkofthemus-clecanbepalpatedastheheadisturnedtotheside.MotorexaminationObservationoftherestingpos-turecanrevealthesymmetryandmaturityofthepassivetone.Itisimportanttokeeptheheadmidlinetoavoidasymmetriesintonere-latedtotheasymmetrictonicneckreflex.Flexortonetendstodevelopfirstinthelowerextremitiesandproceedcephalad.A28-weekinfantwillliewithminimallyflexedlimbsandhaveminimalresistancetopassivemovementofallextremi-ties.Incontrast,at32weeks,thenewborndevelopsflexortoneatthehipsandknees,withsomeresis-tancetomanipulationofthelowerextremities.Thisprogressioncorre-lateswithincreasingmyelinationofthesubcorticalmotorpathwaysoriginatinginthebrainstem.By36weeks,theinfantdevelopsflexionattheelbows,andbyterm,thein-fantisflexedinallextremities.Thequalityoftheinfantsmovementsdevelopsaswell.Forexample,the28-weekinfantwillhavewrithingmovementsoftheextremities,butbytermthemovementsarebestde-scribedaslargeamplitudemovements.A28-weekinfantwithjerkymovementsisabnormalanddrugwithdrawalshouldbesus-pected.Conversely,aterminfantwithchoreoathetoidmovementsshouldbeevaluatedforanumberofpotentialstructuralormetabolicSensoryexaminationInthenewborn,theexamina-tionislimitedtotouchandpin-prick.Particularemphasisshouldbeplacedondermatomalevalua-tionofthelowerextremities,espe-ciallyinthesacralregioninachildwithaneuraltubedefect.Assess-mentofsensationcanbemadebyusingthesharpendofacottonap-plicatoronthefaceandobservingthefacialgrimaceorchangeinstateoftheinfant.Reflexescanbeeasilyelicitedinthebiceps,brachioradialis,knees,andankles.Crossadductorresponsesandunsustainedclonusarenotuncommoninthenewborn.Manychildneurologistsagreethattheplantarresponseisnothelpful,
Figure.Summaryoftheneurologicexaminationwithrespecttogestationalage.ATNRasymmetrictonicneckNEUROLOGY62April(1of2)2004
asmanyfactorsmayelicitflexororextensorresponsesinadvertently.PrimitivereflexesOftheprimitivereflexesthatcanbeelicitedinthenewborn,thefollowingarethemostimportanttoAfullMororeflexconsistsofbi-lateralhandopeningwithupperex-tremityextensionandabduction,followedbyanteriorflexionoftheupperextremities,thenanaudiblecry.Thisisbestelicitedbydrop-pingtheheadinrelationtothebody,intotheexaminershands.Theasymmetrictonicneckre-flexiselicitedbyrotatingtheheadtooneside,withsubsequentelbowextensiontothesidetheheadisturnedandelbowflexiononthesideoftheocciput.Thepalmargraspreflexiselic-itedbystimulatingthepalmwithanobject.Thepalmargraspispresentat28weeksgestation,strongat32weeks,andisstrongenoughat37weeksgestationtoliftthebabyoffthebed.Thisreflexdis-appearsat2monthsofagewiththedevelopmentofavoluntarygrasp.Totesttheplacingreflex,theinfantisheldundertheaxillainanuprightposition,andthedorsalas-pectofthefootisbrushedagainstatabletop.Theinfantshipandkneewillflex,andtheinfantwillappeartotakeastep.Thisreflexisusefulifasymmetryoccursandmayindi-catealesioninthebasalganglia,brainstem,orspinalcord.However,performingthisreflexcanbelim-itedbytheconstraintsoftheiso-lette,endotrachealtube,ormultiplelines.PatternsofneurologicParasagittalcerebralinjuryWithdiffusedecreasedcerebralperfusioninasphyxia,ischemicchangesoccurinthearterialborderzonesofthecerebralhemispheres.Asaconsequence,theneonatewillexhibithypotoniaoftheupperex-tremities,withweaknessparticu-larlyintheshoulders,inadditiontolowerextremityweakness.Periventricularleukomalaciaandparaventricular/intraventric-ularhemorrhageThegerminalmatrixisavascular-richzonecontainingpluri-potentialcellsfromwhichthecortexdevelops.Itissusceptibletobleedinginthepreterminfant.Withabnor-malitiesincerebralperfusion,theseareashemorrhageandoftendevelopinfarctioninthedeepwhitematterofthehemispheres.Asaresult,thesebabiescandevelopinitialweaknessintheirlowerextremities,althoughoftentheymayhaverelativelynor-malexaminations.Asmyelinationprogressesinthecorticospinaltractswithmaturation,however,thein-fantscandevelopincreasedlowerex-tremitytoneandincreasedreflexesbyabout4to5monthsofage.Thisisincontrasttoparasagittalcerebralinjurywherebothupperandlowerextremitiesareinvolved.SpinalcordTraumaticcordlesionscande-velopininfants,especiallyinthesettingofadifficultbreechdeliv-erywithatearinthecervicaldura.ThisresultsinsymmetriclowerextremityparalysiswithsparingofthefaceandcranialnervesandinvolvementofthePeripheralnerveThemostcommoninjuryin-volvingtheperipheralnerveistheproximalcervicalrootsC5,C6,andC7,usuallyinthesettingofatrau-maticdeliverywithshoulderdysto-cia.InErbspalsythereisparalysisofshoulderabduction,elbowflex-ion,andfingerextension,sothatthearmisheldextended,exter-nallyrotatedwithflexionatthewrist.Nobicepsreflexcanbeelic-itedalthoughonemaybepresentinthetriceps.Sensationisdiminishedinthelateralaspectofthearm.NeuromuscularjunctionandInmyastheniagravisandinfan-tilebotulism,diffusehypotoniaandweaknessarepresent,oftenincon-junctionwithCNinvolvement.Incongenitalmyopathies,proximalex-tremityweaknessisprominentandcanbemarkedbylimbdeformitiesiftheonsetoccurredinutero.SeizuresvsjitterinessAcommonconsultfromtheneonatalICUisforseizures.Inanewborn,manymovementssuchassuckingmaybemistakenforsei-zure;ontheotherhand,subtlemovementssuchasbicyclingofthelegsmaybeoverlookedasamani-festationofseizure.AgoodruleofthumbistoobtainanEEGtodeter-mineifseizureactivityispresent.Jitterinessmaybedifficulttodis-tinguishfromseizure,butafewclinicalcluesmayhelp.Jitterinessfromdrugwithdrawaloftenpre-sentswithtremors,whereasclonicactivityismostprominentinsei-zures.Jitterinesstendstobestimulus-sensitive,becomingmostprominentafterstartle,anditsac-tivitycanceasebyholdingontothesarm,neitherofwhichistrueinseizures.Additionally,seizurestendtobeaccompaniedbyauto-nomicchangesaswell.Adetailedneurologicexamina-tioncanbeaccomplishedthroughasystematicapproachandcloseobser-vationofthenewborn,keepinginmindthattheexaminationchangeswithgestationalage.Acarefulexam-inationcanthusguidetheexaminerinchoosingthemostappropriatedi-agnostictests.1.VolpeJJ.Neurologicalevaluation.In:VolpeJJ.Neurologyofthenewborn.4thedition.Philadelphia:W.B.Saunders,2001;103-133.2.PainterMJ.Neurologicalevaluationofnew-borns,infants,andolderchildren.In:Al-brightAL,PollackIF,AdelsonPD.Principlesandpracticeofpediatricneurosurgery.NewYork:Thieme,1999;3-19.April(1of2)2004NEUROLOGY62