Sphincter of Oddi Dysfunction.docx
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Sphincter of Oddi Dysfunction.docx
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SphincterofOddiDysfunction
SphincterofOddiDysfunction:
Introduction
Figure1.LocationofthesphincterofOddiinthebody.
SphincterofOddidysfunctionreferstostructuralorfunctionaldisordersinvolvingthebiliarysphincterthatmayresultinimpedanceofbileandpancreaticjuiceflow.Upto20%ofpatientswithcontinuedpainaftercholecystectomyand10–20%ofpatientswithidiopathicrecurrentpancreatitismaysufferfromsphincterofOddidysfunction.Thisconditionismoreprevalentamongmiddle-agedwomenforunclearreasons
GeneralInfo
WhatisSphincterofOddiDysfunction?
ThesphincterofOddihasthreemajorfunctions:
1)regulationofbileandpancreaticflowintotheduodenum,2)diversionofhepaticbileintothegallbladder,and3)thepreventionofrefluxofduodenalcontentsintothepancreaticobiliarytract.Withtheingestionofameal,thegallbladdercontractsandthereisasimultaneousdecreaseintheresistanceinthesphincterofOddizone.
ThesphincterofOddiconsistsofcircularandlongitudinalsmoothmusclefiberssurroundingavariablelengthofthedistalbileandpancreaticduct.Therearethreediscreteareasofmusclethickness,orminisphincters:
thesphincterpapillae,thesphincterpancreaticus,andthesphinctercholedochus(Figure2).
Figure2.Minisphincters,ordiscreteareasofmuscle,comprisethesphincterofOddi.
Themajorphysiologicroleofthesphincteristheregulationoftheflowofbileandpancreaticjuice.Cholecystokinin(CCK)andnitratesdecreasetheresistanceofferedbythesphincter.Laboratorystudiesobservingtheeffectsofnumerouspeptides,hormones,andmedicationsonthesphincterhavesuggestedamultifactorcontrolmechanismforthesphincterofOddi.
TherearetwotypesofsphincterofOddidysfunction:
1)papillarystenosisand2)sphincterofOddidyskinesia.Papillarystenosisisafixedanatomicnarrowingofthesphincter,oftenduetofibrosis.SphincterofOddidyskinesiareferstoavarietyofmanometricabnormalitiesofthesphincterofOddi.
Symptoms
ThemajorpresentingsymptominpatientswithsphincterofOddidysfunctionisabdominalpain.Thepainischaracteristicallysharp,postprandial,andlocatedintherightupperquadrantorepigastrium.Thepainmaybeassociatedwithnauseaand/orvomiting,maylastforseveralhours,andmayradiatetothebackorshoulderblades.Fever,chills,andjaundiceareuncommonsymptoms.Patientsmayalsopresentwithacuterecurrentpancreatitis.
Anatomy
Thesmoothcircularmusclesurroundingtheendofthecommonbileduct(biliarysphincter)andmainpancreaticduct(pancreaticsphincter)fuseattheleveloftheampullaofVatertobecomethesphincterofOddi(Figure3).
Figure3.AnatomyofthesphincterofOddi
Thismusculatureisembryologically,anatomically,andphysiologicallydifferentfromthesurroundingsmoothmusculatureoftheduodenum.Thenormalappearancethroughtheendoscopeincludesthemajorandminorpapilla.Themajorpapillaextends1cmintotheduodenumwithanorificediameterof1mm.Theminorpapillais20–30mmproximalandmedial.Itsorificeistinyandmaybedifficulttoidentify.Dysfunctionofthismusclemayresultinunexplainedabdominalpainorpancreatitis.
ThesphincterofOddiisadynamicstructurethatrelaxesandcontractstochangethedimensionsoftheampullaofVater(Figure4).
Figure4.ThesphincterofOddi;A,relaxationphase;B,contractionphase.
SphincterofOddidysfunctionisaresultofanatomicandphysiologicabnormalitiesinthedistalcholedochusandsphincter.Avariablelengthofthedistalcholedochusandthepancreaticductareinvestedwithcircularandlongitudinalsmoothmusclefibersthatinterdigitatewiththeextra-ampullarymusclefibersoftheduodenalwalltoformthesphincterofOddi.Minisphincters,orthreediscreteareasofmusclethickness(sphincterpapillae,sphincterpancreaticus,andsphinctercholedochus),comprisethesphincterofOddi.
Uponingestionoffood,thegallbladdercontracts,withasimultaneousdecreaseintheresistanceinthesphincterofOddizone.ThesphincterofOddiisanindependentmotorunitthathasahigh-pressurezoneinthedistalcholedochusapproximately5mmHggreaterthanthepressureinthedistalcommonbileduct.Thiszoneisapproximately5–6mmlong.Thebasalpressureofthesphincteris5–15mmHggreaterthanthecommonbileductpressure,and15–30mmHggreaterthanthepressureintheduodenum.Superimposedonthisrestingpressurearerhythmicphasicwavecontractionsatanamplitudeof50–150mmHgandafrequencyof2–5contractions/minute.
Themajorphysiologicroleofthebiliarysphincterisregulationofbilepassage,withCCKandnitratesdecreasingtheresistanceofferedbythesphincter.Laboratorystudiesobservingtheeffectsofnumerouspeptides,hormones,andmedicationsonthesphincterhavesuggestedthatthereisamultifactorcontrolmechanismofthesphincterofOddi,andthismechanismisadaptedtoprovideocclusiveandpropulsiveinfluencesontheflowofbile.Abnormalitiesinthiscontrolmechanismand/orprocessresultinbiliarycolic.
Causes
Overview
PapillarystenosisandsphincterofOddidyskinesiaarethemajorformsofdysfunction(Figure5).
Figure5.Biliary-typepainresultsfromdysfunctionofthesphincterofOddi;A,stenosisofthesphincterofOddi;B,dysfunctionalmuscle.
PapillarystenosisisastructuralabnormalitywithpartialorcompletenarrowingofthesphincterofOddiduetochronicinflammationandfibrosis(Figure5A).Overallincidenceofpapillarystenosisis2–3%.Associatedconditionsthoughttoresultinpapillarystenosisincludecholedocholithiasis,pancreatitis,traumaticsurgicalmanipulation,nonspecificinflammatoryconditions,andrarely,juxtapapillaryduodenaldiverticula.
InsphincterofOddidyskinesia,functionalabnormalitiesofthesphinctermayresultinbiliary-typepain(Figure5B).Uptoone-thirdofpatientswithunexplainedbiliarypain,ofteninthesettingofpostcholecystectomysyndromewithnormalextrahepatobiliaryandpancreaticsystems,havemanometricevidenceofsphincterofOddidysfunction.ThistypeofdysfunctioniscausedbyaparadoxicalresponsetoCCK,elevatedbaselinepressures,oranincreaseintheamplitudeandfrequencyofthephasiccontractions.
PostcholecystectomySyndrome
PostcholecystectomysyndromeisthemostcommonsyndromeassociatedwithsphincterofOddidysfunction,andoccursinapproximately20%ofpatientswhohaveundergonecholecystectomysurgery.
AmpullaryorPapillaryTumors
Tumorsthatinvolvetheampullaand/orthepapillaryorificemayalsocausestenosisandresultantdysfunctionofthesphincterofOddi.
Diagnosis
Overview
ThediagnosisofsphincterofOddidysfunctionisbasedonahighindexofclinicalsuspicioninpatientswithpersistentorrecurrentbiliarypainaftercholecystectomy.ThepresenceofabnormalbiochemicaltestsofliverfunctionanddilationofcommonbileductishelpfulinconfirmingsphincterofOddidysfunction.Noninvasivescreeningtestssuchasbiliaryscintigraphicandultrasoundstudiesarealsouseful.ThegoldstandardfordiagnosisofsphincterofOddidysfunction,however,remainssphincterofOddimanometry.
TheMilwaukeeBiliaryGroupClassificationofsphincterofOddidysfunction(Table1)suggestscategoriesbasedonclinicalandlaboratoryfindings.TheClassificationalsopredictsoutcomefromendoscopicsphincterotomyorsurgicalsphincteroplasty.
Table1.MilwaukeeBiliaryGroupClassificationforBiliaryDyskinesia
ForTypeIIandIIIpatients,endoscopicmanometryisimportanttodiagnosesphincterofOddidysfunction.TypeIpatientsarebelievedtohavepapillarystenosisandmaybetreatedwithoutfurtherinvestigations.
LaboratoryTests
Biochemicaltestsofliverfunctionmaybenormalormaydemonstratemoderateelevationsofserumaminotransferases(atleasttwo-fold).Testsofliversyntheticfunctionareinvariablynormalintheabsenceofotherdisease.
NoninvasiveDiagnosticStudies
BiliaryScintigraphy
DynamichepatobiliaryscintigraphyafterstimulationwithcholecystokininhasbeenutilizedasanoninvasivetoolintheearlyevaluationofsphincterofOddidysfunction.ResearchersatJohnsHopkinsdevelopedaquantitativescoringsystem(HopkinsScintigraphicScoringSystem)utilizingmultiplescintigraphicparameters(Table2).Atotalscoreof5orgreaterisabnormal.Thisscoringsystemdemonstratescorrelationswith100%sensitivityandspecificitywiththemanometricdiagnosisofsphincterofOddidysfunction(Figures7and8).
Table2.JohnsHopkinsCriteriaforScoringScintigrams
Figure6.Thediffusionofradiolabeledmicrospheres(99m-technetium-DISIDA)innormalanddysfunctionalbiliaryscintigraphy.
Figure7.Stagesofdiffusionovertimeof99m-technetium-DISIDAinbiliaryscintigraphy.
Ultrasound
Fattymeal-stimulatedultrasoundisusedasascreeningtestforsphincterofOddidysfunction.Inthistest,dilationofthebileductafterafattymealsuggestsanobstructiontobileflowandsphincterofOddidysfunction.Unfortunately,thesensitivityandspecificityofthistestislow,soitisnotwidelyused.Morerecently,secretin-stimulatedendoscopicultrasoundhasshownsomepromise,butresultsarestilltoopreliminarytorecommendwidespreaduse.
SecretinenhancedMagneticresonanceCholangiopancreatography(MRCP)
SecretinisahormonethatresultsinincreasedsecretionofpancreaticjuiceandhepaticbileandhenceresultsinbettervisualizationofthepancreaticobiliaryductalanatomyduringMRCP. Thismethodisattractives
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