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Ростовский Государственный Медицинский Университет

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decreasedsensationtolighttouchandpinprickbelowtheirnipples,forinstance,haveaT4sensory level,suggestingthattheirlesionisaroundT4orabove(moreprecisely,thelesionislikelycloserto T6orabove,thankstoLissauertract:ifyourememberfromChapter1,thefirstorderneuronsofthe spinothalamictractrunupalongsidethecordinwhat’sknownasLissauertractforabout2vertebral levelsbeforetheyenterthecord.Don’tworrytoomuchaboutthis;itisrarelyclinicallyrelevant).

Box10.1BilateralACAPathology

Acutepathologyaffectingthebilateralanteriorcerebralartery(ACA)territoryinthebrainisoneothercauseofsuddenonset bilateral lower extremity weakness (see homunculus below; the ACAs supply the cortex predominantly responsibleforlowerextremitymovement).Rapidlyexpandingorbleedingparasagittaltumorsareonepossiblecause. StrokesduetoazygousACA occlusion(acircleofWillisvariantinwhichtheanteriorcommunicatingartery isabsent andtheproximalsegmentsofbothACAsformasingletrunk)areanother.

Areminderofthehomunculusinthecerebralcortex,demonstratingtheproximityofthetwo sidestoeachotherwheremotorinputtothelowerextremitiesoriginates.

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(A)AnazygousACA.IfthesingleACAtrunkisoccluded,bothACAterritoriesareatriskof ischemia.(B)Abigparasagittalmeningioma.A,CourtesyofDr.RobertoSchubert, Radiopaedia.org,rID:17059.B,ReprintedfromHainesDE.NeuroanatomyAtlasinClinical Context.10thed.WoltersKluwer;2018.

Bowel or bladder dysfunction. Dependingontheetiology, patients with acute cord compression may present with underactivity, overactivity, or normal activity of bowel and bladder pathways. Trauma may causeaperiod ofneurogenic spinalshock (seethe Examinationsectiononpage262) resultinginflaccid bowel andbladder tone, which resultinfecalimpactionandoverflow urinary incontinence. Other types of compression above the conus may disrupt coordination between the sphincters and the musculature ofthe bowel or bladder wall,leading toacombination ofurgency and incomplete evacuation. Conus medullaris syndrome, discussed later, leads to flaccid tone resemblingposttraumaticneurogenicshock.

Box10.2DermatomalLandmarks

Herearesomeusefuldermatomelandmarkstoknow.Adermatomeisanareaofskinsuppliedbysensorynervesfrom asinglespinalnerveroot.

C3 Highturtleneck T4 Nipple T10 Navel L1 Inguinalligament L4 Patella

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Thedermatomeperson.Youdonotneedtomemorizethisindividual,butitwillserveasagreat reference.

Box10.3TheASIAImpairmentScale

TheASIA(AmericanSpinalInjuryAssociation)ImpairmentScaleisastandardizedneurologicexaminationthat assessesthedistributionanddegreeofbothmotorandsensorydysfunctionandisusedtohelpclassifyinjury severityandsetgoalsforrehabilitation.

Examination

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Immediatelyfollowingacutespinalcordtrauma,patientscanpresentwithspinalshock,thelossofall spinalcordfunctionbelowthelevelofthelesion.Flaccidparalysisandareflexiaarecharacteristic. Othersymptomsincludeanatonicbladderwithoverflowincontinence,boweldistensionwithsevere constipation,diminishedrectaltone,andsometimessignificantautonomicdysfunction.Spinalshockcan lastanywherefromhourstodaysbeforerecedingtorevealthepatient’strueneurologicfunction.So, duringtheperiodofshock,youcannotaccuratelyprognosticatethepatient’soutcomeorrecovery.

Withtime,theexaminationwillbecomewhatisreferredtoasamyelopathicexamination(i.e.,an examinationconsistentwithspinalcordinjury),characterizedbytypicaluppermotorneuron(UMN) findingssuchasspasticity,hyperreflexia,andclonusbelowthelevelofthelesion.Spinalcordinjuryis primarilyanuppermotorneuroninjury(withtheexceptionofthefewlowermotorneuronsthatare affectedatthelevelofthelesion),andthustheexaminationischaracterizedbyuppermotorneurontype symptoms(seepage20forareview).

TriageandEvaluation

Patientswithtraumaticspinalcordinjuriesshouldbeimmobilizedandtakendirectlytoahospitalsetting. Inanypatientinwhomyoususpectcordcompression,anMRIofthespineisalmostalwaysnecessary.A CTwillshowyoubone(andcanthereforeshownarrowingofthespinalcanal),butdoesnotvisualizethe corditself.

YoucanseethedifferencebetweentheCT(A)ofthecervicalspine(whichnicelyvisualizesthevertebrae, butcan’ttellyoumuchofanythingaboutthecord)andtheMRI(B),whichclearlydelineatesthecordand surroundingthecalspace.(A,reprintedfromBenzelEC.CervicalSpine.5thed.WoltersKluwer;2012.B, modifiedfromBerquistTH.MRIoftheMusculoskeletalSystem.6thed.WoltersKluwer;2012.)

WesaidthisinChapter9,butitisworthrepeating:ifyouareconcernedaboutdamagetothespinal cord,ordercervicalandthoracicspineMRIs.Thereisnoneedforalumbarscan.Thecordendsat

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approximatelyL1;thus,alumbarspineMRIpredominantlyvisualizesthecaudaequina,notthecord.If youaren’tsurewherethelesionlocalizes,youcanorderanMRIoftheentirespine(oftencalleda “spinalsurvey”),butthequalitytendstobeworsethanadedicatedcervicalorthoracicscan.Thisshould serveasanimportantreminderofwhyit’simportanttoknowyouranatomy!

Onceyoudiagnosecordcompression,treatmentdependsentirelyontheunderlyingcause.Traumamay requiresurgery;malignancymayrequireradiation;epiduralabscessmayrequireantibioticsanddrainage.

SpinalCordSyndromes

Thereareseveralspecificsyndromesresultingfromspinalcordcompressionthatdeservespecial mentionbecause,ifyourecognizethem,theycanquicklyhelpyoulocalizetheproblemandinstituterapid treatmentwhereappropriate.

Threeimportant,incompletespinalcordsyndromes(thegreenareasshowthesiteofthelesions).

BrownSequardSyndrome

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BrownSequardsyndromeresultsfromhemisectionofthespinalcord.It’sworthlookingbackatChapter1 toreviewtheanatomyofthesensoryandmotortractsbeforetryingtounderstandthissyndrome.Inmost casesofspinalcordinjury,thesymptomsareoftenincompleteandmixed—thecordisrarelyperfectly hemisectioned,andthedamageisrarelyperfectlysymmetric—butthesymptomsofa“textbook”caseare listedinfullbelow.

Belowthelevelofthespinalcordlesion,you’dexpecttosee:

Ipsilateraluppermotorneuron(UMN)symptoms(duetocorticospinaltractdamage) Ipsilaterallossofvibration,pressure,andproprioception(dorsalcolumndamage) Contralaterallossofpainandtemperature(spinothalamictractdamage;remember,thespinothalamic tract crosses immediately when it enters the cord. Further, because of Lissauer tract, pain and temperaturesensationshouldbelostafewlevelsbelowthelesion)

Atthelevelofthelesion,you’dexpecttosee:

Ipsilaterallowermotorneuron(LMN)symptoms(anteriorhorncelldamage) Ipsilaterallossofallsensation(damagetothespinothalamictractfibersastheycross)

Causesincludetrauma,extrinsiccompressivelesions,tumors,andmultiplesclerosisplaques. Treatmentdependsentirelyontheunderlyingetiology.

AnteriorandCentralCordSyndromes

Anteriorcordsyndromeismostcommonlytheresultoftraumaorinfarctionoftheanteriorspinalartery (whichsuppliesbloodflowtotheanteriortwothirdsofthecord).Symptomsincludebilateralweakness andlossofpainandtemperaturesensationbelowthelevelofthelesion,withpreservationofvibration, pressure,andproprioceptionduetosparingofthedorsalcolumntracts.

Centralcordsyndromeismostoftenseeninolderpatientswithdegenerativecervicalspinedisease andinyoungerpatientswithhyperextensioninjuries(e.g.,fromarearendcarcollision);itcanalsobedue toanexpandingsyrinx,afluidfilledcavitywithinthecord(oftenseeninassociationwithChiari1 malformationsorasaconsequenceofpreviouscordtrauma).Asuspendedsensorylevel(i.e.,alossof sensationinabandorcapelikedistributionacrossthearmsandupperbackwithretainedsensoryfunction inthetrunkandlegs)duetodamageofthespinothalamictractfibersastheycrossischaracteristic, although,ifthelesionextendssufficientlyoutwardtohittheascendingsensorytracts,centralcordlesions canalsocausebilaterallossofsensationbelowthelevelofthelesion.Ifweaknessispresent,itaffects bothupperextremitiesmorethanthelowerextremities,becausethefiberssupplyingthearmsrunmore mediallywithinthecorticospinaltractthanthefiberssupplyingthelegs.

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Centralcordsyndromeoftenonlyaffectsthecrossingfibersofthespinothalamictract,resultingina suspendedsensorylevelorcape-likelossofsensationatapproximatelythelevel(s)ofthelesion,with intactsensationbothaboveandbelow.Alsonotehowthemotorfibersofthelateralcorticospinaltract supplyingthearmsrunmediallytothosesupplyingthelegsandarethereforemorelikelytobe compromised.

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Thecapelikesensorylossthatcanbecausedbycentralcordlesions.

ConusMedullarisandCaudaEquinaSyndromes

Conusmedullarissyndromeisaconstellationofsignsandsymptomsattributedtoinjuryoftheconus; likewise,caudaequinasyndromeistheresultofinjurytothecauda(andthereforetechnicallynotatrue “cord”syndrome).AswithBrownSequard,thesesyndromesarerarelycompleteandcanhavesignificant overlap,butunderstandingthedifferencesisuseful.

ConusMedullarisSyndrome CaudaEquinaSyndrome

Dueto CompressionatvertebrallevelL1/L2 Compressionof2/morespinalrootsbelowL2 Characteristicpresentation Earlybowelandbladdersymptoms Prominentlowerback/legpain Motorsymptoms MixedUMN/LMN(usuallymild) LMN(oftenasymmetric) Sensorysymptoms Saddleanesthesia(S3-5dermatomes) Involvesthedermatomesofwhicheverrootsareaffected Autonomicsymptoms Urinaryretentionandoverflowincontinence,impotence Lesscommonthanwithconusmedullarissyndrome

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Aquickreminderofwhatwe’retalkingabout.

Theconuscontainssacralcordsegmentsandnerveroots.Compression,mostcommonlytheresultof vertebralfracture,trauma,ordischerniation(seeBox10.4),tendstopresentacutely,withearlyand prominentbowelandbladderdysfunction,typicallymildandbilaterallegweakness(thelesioncanand oftendoesaffectboththedescendingUMNsinthecordandtheLMNsexitingthespinalcolumn,since everythingiscrammedintogetherverytightlyhere),andsaddleanesthesia.

LesionsatorbelowtheL2vertebraecandamagethecauda,whichcontainslumbarandsacralnerve roots.Causesincludedischerniation(mostcommonly),lumbarspinalstenosis,epiduralabscessand tumors,aswellasamyriadofinflammatorycausesincludingsarcoidandchronicinflammatory

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demyelinatingpolyneuropathy.Lowerbackpainandpainradiatingdownintothelegsarecommon. Lowerextremityweaknessismoreoftenasymmetric(thenervesaremorespreadouthere),andsensory lossisinthedermatomaldistributionofwhichevernerverootsareaffected(e.g.,ifnerverootsS3–5are affected,itwill,aswithconus,presentwithsaddleanesthesia).

Ineithercase,empiricsteroidscanbeconsideredinanefforttolimitedema,althoughtheevidence regardingtheirefficacyismixedandtheriskofpotentialcomplications(particularlyinfectious complications)mustbeweightedagainstpotentialbenefit.AnMRIisalmostalwayshelpfulfor diagnosis.Ifaninfectiousorinflammatoryconditionissuspected,alumbarpunctureisalsonecessary. Treatmentdependsontheunderlyingetiology:surgeryfordischerniation;radiationforcancer;steroids, plasmapheresis(PLEX),orIVimmunoglobulin(IVIG)foraninflammatorydemyelinating polyradiculopathy(seepage284);etc.

Box10.4DiscHerniation

Discsarelocatedbetweenthevertebraeandactlikecushionstohelpsupportandprotect thespinalcolumn.Theyarecomposedofanouterfibrousring(calledtheannulusfibrosus) andaninner,hydratedlayer(thenucleuspulposus).Discherniationoccurswhenthenucleus pulposusissqueezedoutthroughacrackintheannulusfibrosus.Herniationcanhappen anywhere,butthelumbarspineisthemostcommonlocation(hencedischerniationishighon thedifferentialdiagnosisforconusandcaudasyndromes).Manydischerniationsare asymptomatic.Symptomaticherniationusuallystartswithweekstomonthsofvague,aching backpain(duetogradualdegenerationofthediscandtheligamentsholdingthediscin place),followedbythesuddenonsetofseverepain,tingling,and/ornumbnessthatspreads intotheipsilaterallegduetospinalnervecompression,usuallyinthesettingofexerciseora Valsalvamaneuver(coughingandsneezingarecommonprecipitants).Olderpatientsareat higherrisk,butdischerniationcanoccurinyoungerindividuals,oftenathletes,aswell. Treatmentincludesphysicaltherapy,antiinflammatories,andmusclerelaxants.Manypatients dowellandimproveontheirown,butsurgeryisanoptionifthesetreatmentsfail.

TransverseMyelitis

Thetermtransversemyelitisreferstoinflammationofthespinalcord.Ittendstopresentsubacutely,over hourstodays,withprogressiveweaknessofbotharmsand/orlegs,paresthesias,asensorylevel, autonomicsymptomsincludingbowelandbladderincontinence,sexualdysfunction,andlowerbackand legpain.

Transversemyelitisismerelyadescriptiveterm,referringtosegmentalcordinflammation.Patients withtransversemyelitisrequireanextensiveevaluationtodeterminetheactualetiologicdiagnosis,which guidessubsequenttreatment.Therearemanypotentialunderlyingetiologies,solet’sbreakthemdown intojustafewcategories:

Infectious(WestNilevirus,Zikavirus,herpessimplexvirus,HIV,humanTcellleukemiavirustype 1,Lymedisease,andsyphilisareafewexamples) Systemicautoimmunediseases(transversemyelitiscanbeassociatedwithlupus,sarcoidosis,and

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