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1、脑干损伤Medial(basal)medullarysyndromeusuallyinvolvesthepyramid,partorallofthemediallemniscus,andnerveXII.Ifitisunilateral,itisalsoknownasalternatinghypoglossalhemiplegia(Fig7-12);thetermreferstothefindingthatthecranialnerveweaknessisonthesamesideasthelesion,butthebody
2、paralysisisontheoppositeside.Largerlesionscanresultinbilateraldefects.Theareainvolvedissuppliedbytheanteriorspinalarteryorbymedialbranchesofthevertebralartery.Lateralmedullary,orWallenberg's,syndromeinvolvessome(orall)ofthefollowingstructuresintheopenmedullaonthedo
3、rsolateralside(seeFig7-12):inferiorcerebellarpeduncle,vestibularnuclei,fibersornucleiofnerveIXorX,spinalnucleusandtractofV,spinothalamictract,andsympatheticpathways.(InvolvementofthesympatheticpathwaysmayleadtoHoner'ssyndrome.)Theaffectedareaissuppliedbybranchesoft
4、hevertebralarteryor,mostcommonly,theposteriorinferiorcerebellarartery.AnexampleisprovidedinClinicalIllustration7-1.Basalpontinesyndromescaninvolveboththecorticospinaltractandacranialnerve(VI,VII,orV)intheaffectedregion,dependingontheextentandlevelofthelesion(Fig7-1
5、3).Thesyndromeiscalledalternatingabducens(VI),facial(V),ortrigeminalhemiplegia(V).Ifthelesionislarge,itmayincludethemediallemniscus.Thevascularsupplycomesfromtheperforators,orpontinebranches,oftheanteriorinferiorcerebellarartery.DorsalponssyndromeaffectsnerveVIorVI
6、Iortheirrespectivenuclei,withorwithoutinvolvementofthemediallemniscus,spinothalamictract,orlaterallemniscus.The"lateralgazecenter"isofteninvolved(seeFig8-7).Atamorerostrallevel,nerveVanditsnucleimaynolongerbefunctioning.Theaffectedareaissuppliedbyvariousperforators
7、(pontinebranches)ofthecircumferentialarteries.Peduncularsyndrome,alsocalledalternatingoculomotorhemiplegiaandWeber'ssyndromeinthebasalmidbrain,involvesnerveIIIandportionsofthecerebralpeduncle(Fig7-14).ThereisanerveIIIpalsyonthesideofthelesionandacontralateralhemipa
8、resis(becausethelesionisabovethepyramidaldecussation).Thearterialsupplyisbytheposteriorperforatorsandbranchesoftheposteriorcerebralartery.Benedik
