脑白质病变

1.中毒性：2.遗传性：3.脱髓鞘：4.感染性：5.代谢紊乱：6.血管性：7.肿瘤性：8.脑积水：第一章：中毒性heroinvaporinhalationtoxicity(海洛因吸入中毒)：病因与病理：不纯海洛因放在铝箔上加热，可能产生了某种神经毒性物质。使受累脑白质产生海绵状变性（spongiformdegeneration）。治疗：对症支持，辅酶Q及维生素可能有效。影像学：Involvementofthecerebellumandtheposteriorlimboftheinternalcapsule,withsparingoftheanteriorlimb,appearstobeacharacteristicfindinginthiscondition,helpingtodistinguishitfromothercausesofleukoencephalopathysuchastoluenetoxicityorreversibleposteriorleukoencephalopathy.第一例：参考文献：NeuroimagingFeaturesofHeroinInhalationToxicity:ChasingtheDragon（AJR2003;180:847-850）第二例:参考文献同第一例。可以看出和第一例有类似的影像学特静脉应用海洛因和cocaine(可卡因)中毒男性37岁病人，但是他几乎完全恢复了。参考文献：Toxicleukoencephalopathyafterintravenousconsumptionofheroinandcocainewithunexpectedclinicalrecovery（JNeurol(1999)246:850–851）慢性甲苯（Toluene,ormethylbenzene）吸入中毒：甲苯是一种脂溶性芳香族碳氢化物，作为一种有机溶剂广泛运用于工业中，稀释剂、粘合剂、喷雾剂、涂漆等中都含有它。长期吸入甲苯后，经肺进入血液循环，通过亲脂的血脑屏障，从而对脑产生损害。影像特点：可先出现侧脑室旁的白质病变，再累及半卵园中心皮层下的白质，若接触时间更长（平均8.1年），可出现丘脑对称性T2低信号。（Thefocalpreservationofgraymatter-whitematterdifferentiationinthesubcorticalwhitematterinourpatientswithdiffusechangesindicatesthatwhitematterchangesstartintheperiventricularareaandthenextendintothesubcorticalwhitematter.），但丘脑对称性T2低信号机制尚不明：继发于脱髓鞘和轴突丢失的铁沉积是最可能的机制。（ThedepositionofironcausedbydemyelinationandaxonallossseemstobethemostprobablemechanismforthalamichypointensityonT2-weightedimagesintoluene-containingsolventabuse.）参考文献：CranialMRFindingsinChronicTolueneAbusebyInhalation（AmericanJournalofNeuroradiology23:1173-1179,August2002）接触甲苯3年：AandB,Bilateral,symmetrichyperintensityispresentintheparietalperiventricularwhitematter(arrowheads).Notethatgraymatter-whitematterdifferentiationispreserved.Thewidthsofthecerebralsulciarenormal.Asuggeststhatthehyperintensefindingsmaybecausedbyterminalmyelination,whichisanormalMRimagingfindinginchildren.However,Bshowsthatthelesionsextendtothebilateralcentrumsemiovale,indicatingthathyperintensefindingsweretruelesionsratherthanterminalmyelination.接触甲苯6年：A,Highsignalintensityisseeninthecentrumsemiovale(arrows)onbothsides.Theperipheralcerebralwhitematterandgraymatter-whitematterdifferentiationarepreserved.B,High-signal-intensitychangesinvolvethefrontalandparietalperiventricularwhitematter(arrowheads).Thepatternofwhitematterchangesiscompatiblewiththatoftherestrictedtype.Notethatthelateralventriclesandcerebralsulciareenlarged.接触甲苯11年A,Symmetrichypointensityispresentinthethalami(arrows).Symmetrichyperintensityexistsintheposteriorlimbsoftheinternalcapsule(arrowheads).B,Attheleveloftheposteriorfossa,generalizedincreasedsignalintensityinthecerebellarwhitematteremphasizesthedentatenucleus(arrowheads).C,Atthelevelofmidbrain,rednuclei(arrows)andsubstantianigra(arrowheads)arehypointense.D,Diffusehigh-signal-intensityinthecentrumsemiovalecauseslossofgraymatter-whitematterdifferentiation.Graymatter-whitematterdifferentiationispreservedonlyinthesubcortical-frontalwhitematter(arrow).Thecerebralsulciaremildlydilate甲醇（methanol）中毒：相对少见，通常是意外或自杀性服毒或服用假酒。甲醇在体内能代谢成更具神经毒性的甲醛（formaldehyde）和甲酸（formicacid）。通常最先的临床表现是视力减退，可出现严重的神经系统症状和后遗症。血气分析示严重的高阴离子代谢性酸中毒。特异性的治疗：给予乙醇，和甲醇竞争乙醇脱氢酶，阻止甲醇代谢成更具神经毒性的甲醛和甲酸。影像学特点：ThemostcharacteristicMRfindingsinmethanoltoxicityarebilateralputaminalnecroses,whichmayhavevaryingdegreesofhemorrhage。includingseverealterationsofsubcorticalwhitematterandcentralgraymatteralterationwithsparingofperipheralgraymatter.参考文献：CTandMRImagingFindingsinMethanolIntoxication（AmericanJournalofNeuroradiology27:452-454,February2006）甲氨蝶呤（MTX）中毒甲氨蝶呤是一种常用化疗药：MTXisacellcycle-specificagentthatinhibitstheenzymedihydrofolatereductase,preventingtheconversionoffolicacidtotetrahydrofolicacidandinhibitingcellreplication.Bothhigh-doseintravenousMTXandintrathecalMTXareassociatedwithdemyelination,whitematternecrosis,lossofoligodendroglia,axonalswelling,microcysticencephalomalacia,andatrophyrelativelyselectiveforthedeepcerebralwhitematter。TheincidenceofacuteMTXneurotoxicityrangesfrom3–10%andvarieswiththedoseandrouteofadministrationofMTX.影像学：不对称性，局限性。以半卵园中心为主。参考文献：AcuteMethotrexateNeurotoxicity:FindingsonDiffusion-WeightedImagingandCorrelationwithClinicalOutcome(AmericanJournalofNeuroradiology25:1688-1695,November-December2004)cocaine(可卡因)中毒和精神药物滥用中毒患者1有滥用可卡因史，患者2有精神药物滥用史。影像学特点:Axialfluidattenuatedinversionrecovery(FLAIR)magneticresonanceimagingsequencesofthebrainfrompatient1(A)andpatient2(B).Bothscansshowevidenceofdiffusesymmetricalwhitematterchangesinvolvingtheperiventricularregionandextendingsuperiorlytoinvolvethecoronaradiata.病理特点：Myelinpallorinfrontal(A)andparietal(B)whitematter,contrastedwithnormalmyelinstainingintensityininternalcapsule(C)andcerebellum(D).NotepreservationofsubcorticalUfibresinthefrontalandparietalwhitematter.(AllstainedwithLuxol-FastBlue.)TherewasrelativesparingofthesubcorticalUfibresbutthechangesbecameprogressivelymoreseverefromsuperficialtodeep(fig2,panelsAand(B).Cerebellarandbrainstemwhitematterwerenotinvolved(fig2D).接上例，病理特点：Therewaswidespreadconfluentvacuolardegenerationofthedeepwhitematter,withprofoundaxonallossandevidenceofaxonalinjuryinadjacentnormalappearingwhitema