Head and Neck Infections.docx

Head and Neck Infections.docx

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HeadandNeckInfections

HeadandNeckInfections

Infectionsoftheheadandneckfrombothodontogenicandothercausesareanimportantpartofdailypatientmanagementfororalandmaxillofacialsurgeonsandotherpractitionersinvolvedwiththisanatomicarea.Inmostinstances,infectionsareeasilydealtwithbyproperdiagnosis,removaloftheetiologicfactor,incisionanddrainage,appropriateantibiotictherapy,andsupportivecare.Life-threateninginfectionsarerare,butsuccessfultreatmentdemandsearlyrecognition,propermedicalandsurgicalmanagement,constantvigilance,appreciationofsurgicalanatomy,andunderstandingofpossiblecatastrophicsequelae.

Thischapterdealsprimarilywiththesurgicalmanagementofinfectionsoftheheadandneck,includingprinciplesofassessment,anesthesiaconsiderations,perioperativemanagement,andsurgicalanatomy.Specificanatomiccomplicationsofinfectionsandtheirdiagnosisandmanagementareincluded.

PrinciplesofPatientManagement

MICROBIOLOGYANDPRINCIPLESOFANTIBIOTICTHERAPY

Theoralcavitysupportsthemostcomplexpopulationofbacteriaintheheadandneck.Thisisbecauseofthemultiplemicrosystemsofmicroorganismsfoundintheoralrarityandonandwithintheoralmucosa,toothsurfaces,andgingivalcrevice.Thenasalcavity,sinuses,andtonsillarcryptsalsocontributetothiswidearrayofbacteriaandfungi.

Most（95%）infectionsoftheheadandneckareduetomixedaerobic-anaerobicorganisms,primarilyaerobicandanaerobicgram-positivecocciandanaerobicgramnegativerods.Althoughbeta-lactamantibioticssuchaspenicillinarestilltheprimaryagentsfortreatinginfectionsoftheoralandfacialregions,anaerobessuchasPrevotellaspp.andPorphyromonasspp.seemtobedevelopinganincreasingbeta-lactamresistance.

Itisunderstoodthatathoroughknowledgeofthemicrobiologyofthisareaandoftheprinciplesofappropriateantibiotictherapyarevitaltothesuccessfulmanagementoftheseinfections.Thischapter,however,addressesmainlythesurgicalmanagementofthesepatients.

PATIENTASSESSMENT

Patientspresentingwithheadandneckinfectionsgenerallyhavesignssuggestiveoftheunderlyingprocess.Theseinitialfindingsmayincludepain,swelling,lossoffunction,suppuration,orerythemaoftheaffectedarea.Thesignsandsymptomsmaybeobviousortrivial,orthepatientmaybeextremelyill.Properpatientevaluationisbasedonathoroughhistory,reviewofsystems,andphysicalexamination,andonappropriatelaboratorytestsandimagingstudies,whichmakeuptheinitialdatabase.

HistoryandPhysicalExamination

Adirectedhistoryofthedurationandprogressionofsymptomsshouldbeobtained.Previoustherapyorsurgicalproceduresandinterventionsandtheireffectareimportant.Knowledgeofthepatient'spastmedicalhistoryandareviewofsystemswithanemphasisonunderlyingsystemicdiseases（e.g.,diabetes,renaldisorders,autoimmunedisorders）,drugandalcoholabuse,andtheuseofimmunosuppressivemedications,areessential.

Physicalexaminationbeginswithanoverallassessmentofthepatient.Isthepatientalert,lucid,indistressbecauseofpainorpotentialairwayembarrassment?

Whatisthequalityofphonation?

Doesthepatientappearhydratedorabletotakefluids?

Istheretrismusorextensionoftheneckforairwaymaintenance?

Theanswerstothesequestionsallowthecliniciantoassessthe

severityofthepatient'scondition.Amoredirectedexaminationoftheheadandneckcanbeperformedwithinspection,palpation,andpercussion.Areasoferythema,swelling,ordrainageshouldbeappreciated.Palpationtoassessareasofinduration,fluctuance,andtendernessisimportant.Regionallymphadenopathyandtendernessshouldbeassessed.Bimanualpalpationofthefloorofthemouth,lateralpharyngealwall,submandibulartriangle,andmandibularangleareaprovidesinformationabouttheanatomicspacesinvolvedandsuggestsacelluliticprocessversusabscessformation.Thepresenceofparatrachealswellingandinduration,mobilityofthetongue,andtrismus,alongwithheadposture,mayprovideimportantinformationaboutairwaymanagement.Tendernessandswellingoftheinferiorcervicaltrianglesorsupraclavicularareamaysuggestsignificantextensionoftheinfectionorinvolvementofthemediastinum.Obviously,acompleteandcomprehensiveoralexaminationisimportant,withanemphasisoncaries,periodontaldisease,andtheamountandnatureofexpressedsaliva.Attentiontothesoftpalate,tonsillarfossae,andoro-andhypo-pharynxisimportant,notingswelling,deviation,anddisplacementoftissuesorpurulentdrainage.

Ophthalmologicexaminationisimportant,includingassessmentofperiorbitaloreyelidswelling.Conjunctivitis,epiphora,andptosisofthelidswithproptosisoftheglobearesignificant.Assessmentofextraocularmusclefunctionandpupillaryresponseandfunduscopicexaminationarenecessary.Basicvisualacuitytestsandcranialnerveexamination,includingnervesIII,IV,andVI,mayuncoverorbitalapexextension.

Acompletephysicalassessmentshouldincludepulmonary,cardiovascular,andgeneralizedneurologicexaminations.Specificpositivechestfindingsmayincludetachypnea,decreasedbreathsounds,suprasternalandsupraclavicularretraction（suggestiveofairwaycompromise）,ormediastinalextension.Tachycardiacanbeseeninahyperpyrexic,dehydratedpatient.Thepresenceofmurmurs,valvulardisease,orprostheticimplantsmaybehighlysignificantformanagementofasepticemicpatient.Extremeweakness,hemiplegia,aphasia,orotherlateralizingneurologicsignsmaysuggestintracranialextensionoftheinfectiousprocess.

LaboratoryandImagingStudies

Apatientwithsevereordeepspaceinfectionshouldhavearoutinecompletebloodcountwithadifferentialwhitebloodcellcount.Asedimentationratemaybeinformative.Otherstudiessuchasbloodglucose,liverfunction,electrolytes,totalproteinandalbumin,renalfunction,andhumanimmunodeficiencyvirus（HIV）statusmaybeimportantintheperioperativemanagementofdiabetic,malnourished,dehydratedpatientsorthosewithspecificunderlyingdiseasesorimmunocompromisedstates.PositiveC-reactiveproteinmaybeusefulinchronicinfections,suchasosteomyelitis.

Diagnosticimagingisusedtodiagnose,confirm,andanatomicallydelineateheadandneckinfection.Panoramicradiographsgenerallyassistindeterminingtheetiologyofanodontogenicinfection.Otherplainradiographs,suchasaWaters'vieworposteroanteriorsofttissueandlateralneckviews,provideinformationregardingsinusdisease,airwaydisplacement,andperitrachealandretropharyngealextensionoftheprocess.Themosthelpfuldiagnostictoolsforanacutelyinfectedpatientarecomputedtomography（CT）andmagneticresonanceimaging（MRI）.

Currently,contrastmedium-enhancedandcost-effectivestudy.MRIisconsideredtobeassensitiveasCTforabscessdetection,butnotasspecific.UltrasonographyhasshownsomeapplicationforabscesslocationbutisstillconsideredinferiortoCT.ScintigraphyusingtechnetiumTc99mmethylenediphosphonateandgalliumcitrateGa67scansarehelpfulinthediagnosisandmanagementofosteomyelitisbutprobablyplaynosignificantroleinacutesofttissueinfections.However,anaerobicodontogenicinfectionshavebeendetectedwiththeuseoffluorine-18fluoromisonidazolewithpositronemissiontomography.

ANESTHESIAANDAIRWAYCONSIDERATIONS

Inevaluatingapatientwithafascialspaceinfection,patencyoftheairwayandanesthesiaconsiderationsareoftheutmostconcern.Apatientwhopresentswithahyper-extendedneckandexhibitsopen-mouthednasalbreathingortheinabilitytomaintainanairwayinasupinepositionshouldcauseimmediateconcern.Difficultywiththemanagementoforalsecretions,sorethroat,laboredbreathing,tachypnea,andchangesinvoicequalityaresignsofpartialairwayobstruction.

Trismusandimmobilityofthetongueandfloorofmouth,aswellastonsillar,lateral,andhypopharyngealswelling,mayinterferewiththeabilitytointubatetheairway.Twosimplepreoperativebedsidetestshavebeenusedtopredictadifficultintubation.Inthefirstone,thepatientisseatedateyelevelandaskedtoprotrudethetongue.Iftheuvula,posteriorpharyngealwall,or,worse,softpalateisnotvisualized,adifficultintubationcanbepredicted.Inthesecondtest,ifthedistancefromthethyroidcartilageprominencetothementonislessthan7cm,intubationwillbedifficult.

Otherclinicalmeasurementsofadequateairwayandrespiratoryexchangearepulseoximetryandmeasurementofarterialbloodgases.

Lateralcervicalsofttissuefilmsandachestradiographcanbeusedtoevaluatethepatencyoftheaircolumnintheneckandchest.Narrowinganddeviationoftheaircolumnmaybeseen.Retropharyngealtissuesonanormallateralfilmshouldbe2to7mmatC2and14to22mmatC6.Acommonlyusedmnemonicis"6at2and22at6".Abnormalfindingsinclude

（1）increasedprevertebralsofttissuethicknessofgreaterthan6mmintheretropharyngealarea,orincreasedsofttissuethicknessofgreaterthan14mmforchildrenand22mmforadultsintheretrotrachealarea;

（2）presenceofairintheprevertebralsofttissues;（3）lossofnormallordoticcurvatureofthespine;（4）presenceofaforeignbody;and（5）displacementorlossoftheprevertebralfatline.ApositivefindinginalateralneckfilmshouldbefollowedbyaCTscantoconfirmthediagnosis.

AusefulalgorithmformanagementoftheairwaywaspublishedbyZideandLimchayseng（Fig.4-4）.Ifthecordscanbevisualized,thenoralintubation,eveninalateralposition,canb