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WorkupshouldincludeanMRI,EEG,andbothserumandCSFserologictesting(mostofthe
autoantibodiesarebesttestedforintheserum,butsome,mostnotablyanti-NMDA,aremoresensitivein
theCSF).Whenappropriate,acomprehensivemalignancyscreenshouldbeperformedaswell.
Treatment
Treatmentwithimmunotherapy(mostoftencorticosteroids,IVimmunoglobulin,andplasmapheresis;
rituximabistypicallysecondorthirdline)shouldneverbedelayedbyantibodycharacterizationor
malignancydiagnosisinpatientspresentingwithaclassicautoimmuneencephalitissyndrome.Oncethe
specificsyndromeisidentified,treatmentcanbenarrowedandrefined.Recoveryisvariablebutcanbe
completeornearcompleteiftreatmentisstartedearly.
YourPatient’sFollow-up:Emmapresentedwithinternuclearophthalmoplegia,afinding
thatishighlysuggestiveofMSinapatientherage.Herhistoryofanepisodeofleg
numbnessayearearlierwouldconstituteasecondlesiondisseminatedintimeandspace,
buthistoricalevidencehastobecarefullyscrutinizedinallpatients.EmmaneededanMRI,
anditconfirmedthepresenceofseverallesions,someclinicallysilent,consistentwithMS.
Shewastreatedwithhigh-doseglucocorticoids,andherdoublevisionresolved.Shewas
startedondisease-modifyingtherapysoonafter.Severalyearsoutshecontinuestodo
extremelywellwithonlyonemildattackofopticneuritisandnoprogressivedisability.
Younowknow:
1. MSistheresultofimmune-mediateddemyelinationandaxonaldestructionofneuronsintheCNS.
2. It is classically defined by the dissemination of clinical attacks in space and time; the use of MRI and testing for CSF-specific
oligoclonalbandshasbroadenedthedefinition.This isimportant,becauseearly diagnosis allowsforearlytreatment,whichcanmodify
thecourseofthedisease.
3. Mostpatients with MShaverelapsingremittingdisease,for whichthere are manydisease modifyingmedications;somepatientswill
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haveprimaryprogressivedisease,andwenowhavemedicationforthataswell.
4. Onemoretime—early diagnosisandtreatmentmatters,andevenpatientswithclinicallyisolatedsyndrome(CIS)shouldbeconsidered
fordiseasemodifyingtherapy.
5. AcuteexacerbationsaretreatedwithseveraldaysoforalorIVcorticosteroids,butsteroidsdonotmodifylong-termoutcome.
6. Whenchronic,disablingcomplicationsdevelop,symptomatictherapyisavailablethatcan,inmanypatients,significantlyimprovequality
oflife.
7. WomenwithMScanhavenormalpregnanciesandsafelybreastfeed.
8. The differential diagnosis of MS is broad and includes neuromyelitis optica spectrum disorder (NMOSD) and acute disseminated
encephalomyelitis(ADEM).
9. Autoimmuneencephalitiscomesinmanyvarieties,andthelistofrelevant autoantibodiesisgrowingbytheday.Thegood news?The
clinicalpresentationisofteneasilyrecognizable,andyoudonotneedtowaitforantibodyconfirmationtobegintreatment.
1
MOGantibodydiseaserepresentsanoverlappingbutlikelyclinicallydistinctsyndromethatcanbeassociatedwithbothmonophasicand
relapsingattacksofdemyelination.ItcancloselyresembleAQP4disease,butittendstoaffectyoungerpatientsandoftenhasamore
favorableoutcome,withagenerallygoodresponsetosteroidtherapy.
2
Thestructuresofthelimbicsystemareinvolvedinregulatingbehavior,emotionsandestablishinglong-termmemory.
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C H AP T E R 1 0
TheSpinalCord
Inthischapter,youwilllearn:
1. Alittlemorespinalcordanatomy
2. Howtorecognizeacutespinalcordcompression—it’simportant!
3. Howtodistinguishconusmedullarissyndromefromcaudaequinasyndrome
4. Allabouttransversemyelitis:whatcausesit,howitpresents,andhowtotreatit
5. How B12 deficiency, copper deficiency, and nitrous oxide abuse can damage the spinal
cord
CASE10
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YourPatient:Priya,a22yearoldmarketingexecutive,presentstotheemergency
departmentafterslippingandfallinginthestreetthismorning.Shesaysshe’sbeenfeeling
weakforthepastfewdays,withtinglinginbothherfeetandprogressivedifficultywalking.
Whenshewokeupthismorninghersymptomswereworse,andshewasonherwaytosee
herdoctorwhenshefell.Whenshegottohisoffice,hesenthertotheemergency
departmentforanexpeditedworkup.Onexamination,hervitalsarestable.Sheisweakin
bothofherlegs,leftslightlyworsethanright,flexormusclesslightlyworsethanextensors.
Heranklejerkandpatellarreflexesarebrisk,andshehasseveralbeatsofclonusateach
ankle.Hersensationtolighttouchisdecreasedinbothlegs,andwhenyoutestpinprick
sensationwithasafetypin,youfindthatshefeelstheprickmuchlesssharplyeverywhere
fromhertoesuptoabandthatcirclesherwaistjustafewinchesbelowhernavel.Shehas
nopain.What’sthenextstepinyourmanagement?
Inthischapter,wewillfocusonhowtorecognizespinalcordpathology,whichisoftenseriousand
sometimesamedicalemergency.Chapter1hasalreadyprovidedyouwithadetailedlookatthemotor
andsensorytractsastheyascendanddescendthecord,butasChapter1isbynowmanypagesinyour
past,let’sstartwithaquickreviewofbasiccordanatomy.
BasicAnatomy
Thespinalcordbeginswherethebrainstemends,andextends(inadults)toapproximatelytheL1
vertebra.ThecorditselfispartoftheCNS,servingasaconduitbetweenthebrainandtherestofthe
body.
There are 33 vertebrae. Twentyfour are articulating—7 cervical, 12 thoracic, and 5 lumbar
vertebrae—and9arefused—5sacralvertebrae (fusedinto the sacrum)and 4coccygealvertebrae
(fusedintothecoccyx,or“tailbone”).
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The33vertebrae.
Thereare31pairedspinalnervesthatexitthecord:8cervical,12thoracic,5lumbar,5sacral,and
1coccygeal.TheC1toC7spinalnervesexitthecordabovetheircorrespondingvertebrae(e.g.,the
third cervical nerve, C3, exits between thesecond and third cervical vertebrae), whereas C8 on
down exit below (e.g., T2 exits between the second and third thoracic vertebrae). Each nerve
containsadorsalroot(carryingsensoryafferents)andaventralroot(carryingmotorefferents).
The lower extentofthecordcontains2importantstructures.Thefirstistheconusmedullaris, the
verycaudal tip ofthecord, whichterminates atapproximatelythe L1 vertebra (in neonates, it is
closer to L3). Thesecondis the caudaequina, a bundle of nerve roots derived from the second
lumbarcordsegmenttothefirstcoccygealcordsegmentthatextendsbelowthecord(caudaequina
isLatinfor“horse’stail”reflectingitsbundledandsplayedappearance).
Likethebrain,thespinalcordiscoveredin3layersofmeninges.Thedura(thetoughest,outermost
layer)extendsapproximatelytotheS2vertebral level(caudaltowherethe cord ends)andinserts
into the coccyx. The arachnoid also extends to S2 but closes on itself, forming a sealed sac of
cerebrospinalfluid(CSF)thatbathesthecord.Thepia(themostdelicate,innermostlayer)clingsto
thecorduntilitgatherstogetheratL1(wherethecordends)intoatight,stringlikebundlecalledthe
filum terminale that helps to anchor the cord in place and, along with the dura, inserts into the
coccyxatS2.
Itiscriticaltodistinguishcordlevelsfromvertebrallevels.Theterminationofthecordisatroughly
theL1vertebrallevel,whereasthearachnoidspaceextendstotheS2vertebrallevel,resultinginalarge,
safelyaccessiblespacefromwhichtoobtainCSFvialumbarpuncture(seeChapter1fordetails).
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(A)Thelowerspinalcord.(B)Thethreelayersofmeningessurroundingthecord.Thedura(pink)endsat
S2andinsertsintothecoccyx.Thearachnoid(orange)formsaclosedsacofCSFthatbathesthecord.
Thepia(purple)gathersintothefilumterminaleandthen,likethedura,insertsintothecoccyxatS2.(C)
WhatthisallactuallylookslikeonanMRIshowingthelowerthoracicandlumbarspine.Youcanseethe
splayedappearanceofthebundleofnerverootsextendingbelowthecord.(C,modifiedfromHainesDE.
NeuroanatomyAtlasinClinicalContext.10thed.WoltersKluwer;2018.)
Themajormotortractthatdescendsthroughthecordisthecorticospinaltract.Theseneuronsstart
outinthemotorcortexofthebrain,rundownthecordmostlyinthelateralwhitematter,andsynapse
onlowermotorneurons(LMNs;theanteriorhorncells),whichthenexitthecordandtraveltotheir
target muscles. The two major sensory tracts are the dorsal column/medial lemniscus tract and
spinothalamic tract, which carry pressure/vibration/proprioception and pain/temperature,
respectively.SeeChapter1foradetailedreview.
Thegraymatterofthecord(shapedlikeabutterfly)isorganizedintotwoventral(anterior)hornsandtwo
dorsal(posterior)horns.Thesurroundingwhitematter,whichcarriestheascendinganddescending
tracts,includestheventral,dorsal,andlateralfuniculi.Notethatthisorganizationisoppositethatwhichwe
seeinthebrain,wherethegraymatterofthecortexliesontheoutsideandthewhitemattertractslie
deeperwithin.
AcuteSpinalCordCompression
Acutecordcompressionisatrueneurologicemergency.Despiteimprovementsinearlydiagnosisand
treatment,itremainsanoftendevastatinganddebilitatingevent.Althoughtreatmentofcordcompression
ismoreoftenneurosurgicalthanneurological,itisimportanttounderstandthepathogenesisofcord
compressionand,especially,tobeabletorecognizeitwhenyouseeit.Youmustknowhowtodistinguish
theacuteonsetweaknessornumbnesscausedbycordcompressionfromthatcausedbyconfounding
diagnosessuchasstroke,GuillainBarresyndrome,orseizure(amongothers)soyoucanquicklyhelpto
guidemanagement.Treatmentdependsentirelyontheunderlyingetiology.
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Anexampleofcervicalcordcompressionbyaherniateddisc(whitearrow),onanMRI.(Modifiedfrom
GrauerJN.OKU12OrthopaedicKnowledgeUpdate.WoltersKluwer.)
Causes
Importantcausesofacutespinalcordcompressioninclude:
Trauma.Motorvehicle accidents, sportsinjuries,falls,andgunshotwoundsarethemostcommon
causesoftraumaticspinalcordinjury.Over12,000newcasesoftraumaticspinalcordinjuryoccur
everyyearintheUnitedStates.
Malignancy.Almostanycancercanmetastasizetothespine,butprostate,lung,andbreastcanceras
well as multiple myeloma are the most likely to involve the vertebrae. Once seeded within the
vertebrae,thesetumorscaninvadetheepiduralspace,resultingincordcompressionfrombothmass
effectandpathologiccompressionfracturesaswellasfromtheobstructionofvenousbloodoutflow
andsubsequentcordedema.
Epidural abscess. Risk factors include intravenous (IV) drug abuse, immunocompromised state,
spinaltrauma,andspinalsurgery.Epiduralabscessesclassicallypresentwithatriadofsymptoms:
fever,focalbackpain,andneurologicdeficits.Staphylococcusaureusisthemostcommoncausative
organism.
Epidural hematoma.Spinalepidural hematomas are usuallytheconsequence ofspinal trauma or
surgery, often in patients with a baselinepropensity to bleed, such as those onanticoagulationor
who have thrombocytopenia. Spontaneous spinal epidural hematomas are rare. Because they are
mostoftencausedbyvenous(asopposedtoarterial)bleeding,symptomstendtoevolveoverhours
todays,althoughtheycansometimespresentmoreacutely.
ClinicalPresentation
Spinalcordanatomyiscomplicated,butrecognizingacutecordcompressionisusuallyprettyclearcut.
Themostcommonpresentingsymptomsarelistedbelow.Nomatterwhatmedicalorsurgicalfieldyou
choose,learntheseredflags:youwilllikelyencounterhundredsifnotthousandsofpatientswithback
painoverthecourseofyourcareers,thevastmajorityofwhomarenotexperiencingacutecord
compression,soknowingwhentobeworriedforcordcompressionandwhentoinitiateimmediate
evaluationandtreatmentiscrucial.
Bilateralextremityweakness.Patientswhopresentwithacuteonsetweaknessofbotharmsand/or
bothlegs,withoutanyfacialweakness1havecordpathologyuntilprovenotherwise.Theweakness
isoftenasymmetric(i.e.,onelegisaffectedmorethantheother)andisoftenassociatedwithatleast
1 or 2 of the other features listed below. This is not to say that all patients with bilateral leg
weakness have acute cord compression (GuillainBarre syndrome, for instance, can cause this,
althoughittypicallyprogressesoverthecourseofdays,nothours;seepage284).Butpatientswith
bilateralweaknessofthearmsand/orlegsalmostalwaysneedanexpeditedworkuptoexcludecord
compressionbeforeyouconsiderothercauses.
Asensorylevel.Asensorylevelisdefinedasthemostcaudal(thatis,thelowest,orfurthestfrom
thehead)dermatomallevel (seeBox10.2 onpage261)atwhichbothlighttouchandpinprickare
intact,anditindicatesapossiblecordlesioneitherATorslightlyABOVEthatlevel.Patientswith
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