USMLE题库Neuro(一)11-20

Neuro1题库Q11A27-year-oldfemaleisbeingevaluatedforamenorrhea.Sheasksifshecanalsogetaneyeexambecauseshehashaddifficultydrivingrecently.Shesaysthatsheisafraidtochangelanesbecauseshecannotseecarscatchingupfromeithertheleftortheright.Thispatientmostlikelysuffersfromwhichofthefollowing?A.PilocyticastrocytomaB.PinealomaC.PituitaryadenomaD.MedulloblastomaE.VestibularschwannomaF.EpendymomaA11Correctanswer:CLossofperipheralvisionsuggestsbitemporalhemianopsia,whichiscausedbypressureonthecentralpartoftheopticchiasm.Themostcommoncauseofbitemporalhemianopiaisapituitarytumor.Pituitarytumorscanalsosecretehormones,causingendocrinedisorders.Aprolactin-secretingpituitaryadenomaisthemostlikelycauseofboththispatient'samenorrheaandvisualdefects.(ChoiceA)Pilocyticastrocytomasarethemostcommonbraintumorsinchildren.Theymostcommonlyoccurinthecerebellumandmaycauseataxia.Nausea,vomiting,andheadachemayalsobepresentasaresultofincreasedintracranialpressure.(ChoiceB}Pinealomaisagenerictermforatumorofthepinealregion.Mostoften,theyaregerminomas.Thesetumorsoccurinchildrenandcauseobstructivehydrocephalus,Parinaudsyndrome,andprecociouspuberty.(ChoiceD)Medulloblastomasarethesecondmostcommonbraintumorinchildren.Theyarelocatedinthecerebellumandmostcommonlycauseheadacheandgaitataxia.(ChoiceE)Vestibularschwannoma(acousticneuroma)isassociatedwithsymptomsofcompressionofCNVIII,includingsensorineuralhearinglossandtinnitus.(ChoiceF)Ependymomasarethethirdmostcommonbraintumorsinchildren.Theyariseinthewallsoftheventriculi,hamperCSFflow,andcausehydrocephalus.EducationalObjective:Pituitaryadenomascausesymptomsfrommasseffectandoftenproduceendocrinedisordersfromthevarioushormonesthattheycanproduce.Prolactinomasarethemostcommonadenoma—excessprolactincausesamenorrheaandgalactorrhea.Bitemporalhemianopsiafromcompressionoftheopticchiasmiscommon.Q12A14-year-oldboypresentswithnausea,vomiting,generalizedheadache,ataxia,andvisualcomplaints.Theheadacheshaveawokenhimnightlyforthepastsixweeks.MRIrevealsacystictumorinthecerebellum.Biopsyofthetumorrevealsawell-differentiatedneoplasmcomprisedofspindlecellsthathavehair-likeglialprocessesandareassociatedwithmicrocysts.ThesecellsaremixedwithRosenthalfibersandgranulareosinophilicbodies.Basedonthesefindings,themostlikelydiagnosisiswhichofthefollowing?A.PilocyticAstrocytomaB.GlioblastomamultiformeC.MedulloblastomaD.EpendymomaE.NeuroblastomaA12Correctanswer:AJuvenilepilocyticastrocytomasusuallyariseinthecerebellum,brainstem,hypothalamicregion,oropticpathways.Microscopically,pilocyticastrocytomasarewell-differentiatedneoplasmscomprisedofspindlecellswithhair-likeglialprocessesthatareassociatedwithmicrocysts.ThesecellsaremixedwithRosenthalfibersandgranulareosinophilicbodies.(ChoiceB)GBMsoccurmostofteninthesubcorticalwhitematterofthecerebralhemispheres.Whenatumorinthefrontalcortexspreadsacrossthecorpuscallosumintothecontralateralhemisphere,itcreatestheappearanceofabilateralsymmetricallesion，hencethetermbutterflyglioma.GBMsarecomposedofpoorly-differentiated,often-pleomorphicastrocyticcellswithmarkednuclearatypiaandbriskmitoticactivity.Necrosisisanessentialdiagnosticfeature,andprominentmicrovascularproliferationiscommon.(ChoiceC)Medulloblastoma(primitiveneuroectodermaltumor,orPNET)isthesecondmostcommonposteriorfossatumorinchildren.Onmicroscopicexamination,cellsaresmallandpoorlydifferentiated,withscantcytoplasmandlittlestroma.Ahighmitoticindexiscommon.ClassicHomer-Wrightrosettescanbeseeninonefifthofcases(ChoiceD)Ependymomasaccountfor10%ofposteriorfossatumorsinchildren.Intracraniallesionsusuallyoccurinfratentorially,arisingfromtheroofofthefourthventricleinchildren,whilespinalependymomastypicallyoccurinadults.Histologically,ependymalpseudorosetteswithglialfibrillaryacidicprotein(GFAP)-positiveprocessestaperingtowardbloodvesselscharacterizeependymomas.(ChoiceE)Neuroblastomasarethemostcommonextracranialsolidtumorsoccurringinchildren.Undifferentiatedneuroblastomasaresmall,round,blue-celltumors.Aneuriticprocess,alsocalledneuropil,isapathognomonicfeatureofneuroblastomacells.NSE，chromogranin，synaptophysin，andS-100immunohistochemicalstainsareusuallypositive.Morethan90%ofpatientshaveelevatedurinarylevelsofhomovanillicacid(HVA)and/orvanillylmandelicacid(VMA).ThemostimportantbiologicmarkerisMYCN(N-MYC)o\chromosome2.EducationalObjective:Acystictumorinthecerebellumofachildismostlikelyapilocyticastrocytoma.Biopsywillshowawell-differentiatedneoplasmcomprisedofspindlecellswithhair-likeglialprocessesthatareassociatedwithmicrocysts.ThesecellsaremixedwithRosenthalfibersandgranulareosinophilicbodies.Q13A7-year-oldmalewhosefamilyrecentlyimmigratedtotheUSexperiencesataxia,myoclonus,andvisualproblems.Asampleofbraintissueisobtained,andanRNAviruscontaininghemagglutinininitscapsidisculturedfromthesample.Thispatientmostlikelysuffersfromwhichofthefollowing?A.GeneralparesisB.ProgressivemultifocalleukoencephalopathyC.SubacutesclerosingpanencephalitisD.Creutzfeldt-JakobdiseaseE.Centralpontinemyelolysis(F.ProgressivesupranuclearpalsyG.MultiplesclerosisH.Guillain-Barresyndr