Hypertensive Encephalopathy
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Hypertensive Encephalopathy Author: Irawan Susanto, MD, FACP; Chief Editor: Michael R Pinsky, MD, CM, Dr hc, FCCP, MCCM more... Updated: Apr 14, 2015 Background The term hypertensive encephalopathy was introduced in 1928 to describe the encephalopathic findings associated with the accelerated malignant phase of hypertension. The terms accelerated and malignant were used to describe the retinal findings associated with hypertension, as follows: Accelerated hypertension is associated with group 3 KeithWagenerBarker retinopathy, which is characterized by retinal hemorrhages and exudates on funduscopic examination Malignant hypertension is associated with group 4 KeithWagenerBarker retinopathy, which is characterized by the presence of papilledema, heralding neurologic impairment from an elevated intracranial pressure (ICP) With adequate control of hypertension, less than 1% of patients experience a hypertensive crisis. A hypertensive crisis is classified as either a hypertensive emergency or a hypertensive urgency, [1] as follows: Acute or ongoing vital target organ damage (eg, damage to the brain, kidney, or heart) in the setting of severe hypertension is considered a hypertensive emergency; a prompt reduction in blood pressure is required within minutes or hours The absence of target organ damage in the presence of a severe elevation in blood pressure (with diastolic blood pressure frequently exceeding 120 mm Hg) is considered a hypertensive urgency; a reduction in blood pressure is required within 2448 hours A continuum exists between the clinical syndromes of hypertensive urgency and emergency; hence, the distinction between the 2 syndromes may not always be clear and precise in practice. [2] Hypertensive encephalopathy refers to the transient migratory neurologic symptoms that are associated with the malignant hypertensive state in a hypertensive emergency. The clinical symptoms are usually reversible with prompt initiation of therapy. In the evaluation of an encephalopathic patient, it is vital to exclude systemic disorders and various cerebrovascular events that may present with a similar constellation of clinical findings. Pathophysiology The clinical manifestations of hypertensive encephalopathy are due to increased cerebral perfusion from the loss of bloodbrain barrier integrity, which results in exudation of fluid into the brain. In normotensive individuals, an increase in systemic blood pressure over a certain range (ie, 60125 mm Hg) induces cerebral arteriolar vasoconstriction, thereby preserving a constant cerebral blood flow (CBF) and an intact bloodbrain barrier. In chronically hypertensive individuals, the cerebral autoregulatory range is gradually shifted to higher pressures as an adaptation to the chronic elevation of systemic blood pressure. [3] This adaptive response is overwhelmed during a hypertensive emergency, in which the acute rise in systemic blood pressure exceeds the individual’s cerebral autoregulatory range, resulting in hydrostatic leakage across the capillaries within the central nervous system (CNS). Brain MRI scans have shown a pattern of typically posterior (occipital greater than frontal) brain edema that is reversible. This usually is termed reversible posterior leukoencephalopathy or posterior reversible encephalopathy syndrome (PRES). [4] With persistent elevation of the systemic blood pressure, arteriolar damage and necrosis occur. The progression of vascular pathology leads to generalized vasodilatation, cerebral edema, and papilledema, which are clinically manifested as neurologic deficits and altered mentation in hypertensive encephalopathy. Etiology The most common cause of hypertensive encephalopathy is abrupt blood pressure elevation in a chronically hypertensive patient. Other conditions that can predispose a patient to elevated blood pressure and cause the same clinical situation include the following: Chronic renal parenchymal disease Acute glomerulonephritis Renovascular hypertension Withdrawal from hypertensive agents (eg, clonidine) Encephalitis, meningitis Pheochromocytoma, reninsecreting tumors Sympathomimetic agents (eg, cocaine, amphetamines, phencyclidine [PCP], and lysergic acid diethylamide [LSD]) Eclampsia and preeclampsia Head trauma, cerebral infarction Collagen vascular disease Autonomic hyperactivity Vasculitis Ingestion of tyraminecontaining foods or tricyclic antidepressants in combination with monoamine oxidase inhibitors (MAOIs) Epidemiology and Prognosis
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Transcript of Hypertensive Encephalopathy
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4/27/2015 HypertensiveEncephalopathy
http://emedicine.medscape.com/article/166129overview#a0104 1/3
HypertensiveEncephalopathyAuthor:IrawanSusanto,MD,FACPChiefEditor:MichaelRPinsky,MD,CM,Drhc,FCCP,MCCMmore...
Updated:Apr14,2015
BackgroundThetermhypertensiveencephalopathywasintroducedin1928todescribetheencephalopathicfindingsassociatedwiththeacceleratedmalignantphaseofhypertension.Thetermsacceleratedandmalignantwereusedtodescribetheretinalfindingsassociatedwithhypertension,asfollows:
Acceleratedhypertensionisassociatedwithgroup3KeithWagenerBarkerretinopathy,whichischaracterizedbyretinalhemorrhagesandexudatesonfunduscopicexaminationMalignanthypertensionisassociatedwithgroup4KeithWagenerBarkerretinopathy,whichischaracterizedbythepresenceofpapilledema,heraldingneurologicimpairmentfromanelevatedintracranialpressure(ICP)
Withadequatecontrolofhypertension,lessthan1%ofpatientsexperienceahypertensivecrisis.Ahypertensivecrisisisclassifiedaseitherahypertensiveemergencyorahypertensiveurgency,[1]asfollows:
Acuteorongoingvitaltargetorgandamage(eg,damagetothebrain,kidney,orheart)inthesettingofseverehypertensionisconsideredahypertensiveemergencyapromptreductioninbloodpressureisrequiredwithinminutesorhoursTheabsenceoftargetorgandamageinthepresenceofasevereelevationinbloodpressure(withdiastolicbloodpressurefrequentlyexceeding120mmHg)isconsideredahypertensiveurgencyareductioninbloodpressureisrequiredwithin2448hours
Acontinuumexistsbetweentheclinicalsyndromesofhypertensiveurgencyandemergencyhence,thedistinctionbetweenthe2syndromesmaynotalwaysbeclearandpreciseinpractice.[2]
Hypertensiveencephalopathyreferstothetransientmigratoryneurologicsymptomsthatareassociatedwiththemalignanthypertensivestateinahypertensiveemergency.Theclinicalsymptomsareusuallyreversiblewithpromptinitiationoftherapy.Intheevaluationofanencephalopathicpatient,itisvitaltoexcludesystemicdisordersandvariouscerebrovasculareventsthatmaypresentwithasimilarconstellationofclinicalfindings.
PathophysiologyTheclinicalmanifestationsofhypertensiveencephalopathyareduetoincreasedcerebralperfusionfromthelossofbloodbrainbarrierintegrity,whichresultsinexudationoffluidintothebrain.Innormotensiveindividuals,anincreaseinsystemicbloodpressureoveracertainrange(ie,60125mmHg)inducescerebralarteriolarvasoconstriction,therebypreservingaconstantcerebralbloodflow(CBF)andanintactbloodbrainbarrier.
Inchronicallyhypertensiveindividuals,thecerebralautoregulatoryrangeisgraduallyshiftedtohigherpressuresasanadaptationtothechronicelevationofsystemicbloodpressure.[3]Thisadaptiveresponseisoverwhelmedduringahypertensiveemergency,inwhichtheacuteriseinsystemicbloodpressureexceedstheindividualscerebralautoregulatoryrange,resultinginhydrostaticleakageacrossthecapillarieswithinthecentralnervoussystem(CNS).BrainMRIscanshaveshownapatternoftypicallyposterior(occipitalgreaterthanfrontal)brainedemathatisreversible.Thisusuallyistermedreversibleposteriorleukoencephalopathyorposteriorreversibleencephalopathysyndrome(PRES).[4]
Withpersistentelevationofthesystemicbloodpressure,arteriolardamageandnecrosisoccur.Theprogressionofvascularpathologyleadstogeneralizedvasodilatation,cerebraledema,andpapilledema,whichareclinicallymanifestedasneurologicdeficitsandalteredmentationinhypertensiveencephalopathy.
EtiologyThemostcommoncauseofhypertensiveencephalopathyisabruptbloodpressureelevationinachronicallyhypertensivepatient.Otherconditionsthatcanpredisposeapatienttoelevatedbloodpressureandcausethesameclinicalsituationincludethefollowing:
ChronicrenalparenchymaldiseaseAcuteglomerulonephritisRenovascularhypertensionWithdrawalfromhypertensiveagents(eg,clonidine)Encephalitis,meningitisPheochromocytoma,reninsecretingtumorsSympathomimeticagents(eg,cocaine,amphetamines,phencyclidine[PCP],andlysergicaciddiethylamide[LSD])EclampsiaandpreeclampsiaHeadtrauma,cerebralinfarctionCollagenvasculardiseaseAutonomichyperactivityVasculitisIngestionoftyraminecontainingfoodsortricyclicantidepressantsincombinationwithmonoamineoxidaseinhibitors(MAOIs)
EpidemiologyandPrognosis
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4/27/2015 HypertensiveEncephalopathy
http://emedicine.medscape.com/article/166129overview#a0104 2/3
Ofthe60millionAmericanswithhypertension,lessthan1%developahypertensiveemergency.Themorbidityandmortalityassociatedwithhypertensiveencephalopathyarerelatedtothedegreeoftargetorgandamage.Withouttreatment,the6monthmortalityforhypertensiveemergenciesis50%,andthe1yearmortalityapproaches90%.
Hypertensiveencephalopathymostlyoccursinmiddleagedindividualswhohavealongstandinghistoryofhypertension.Hypertensioningeneralismoreprevalentinmenthaninwomen.Thefrequencyofhypertensiveencephalopathyinvariousethnicgroupscorrespondstothefrequencyofhypertensioninthegeneralpopulation.Hypertensionismoreprevalentinblackpeople,exceedingthefrequencyinotherethnicminoritygroups.Theincidenceofhypertensiveencephalopathyislowestinwhitepeople.
PatientEducationReferpatientstoadietitiantoreducetheriskofvascularandhypertensivedisease.Encouragelifestylemodifications,includingsmokingcessation,increasingexercise,moderationofalcohol,andavoidanceoftobacco.
Educatepatientsaboutmedicationadherenceandcompliance,andstronglyemphasizetheneedformedicalcompliance.Explaintheeffectsofuncontrolledhypertension,includingthecomplicationsofpersistenthypertension.Informpatientsaboutsignsofacutetargetorgandamage,includingvisualchanges,persistentheadaches,andneurologicalchanges.
ContributorInformationandDisclosuresAuthorIrawanSusanto,MD,FACPClinicalProfessorofMedicine,DirectorofPulmonaryConsultationandProcedures,DivisionsofInterventionalPulmonologyandCriticalCare,UniversityofCalifornia,LosAngeles,DavidGeffenSchoolofMedicine
IrawanSusanto,MD,FACPisamemberofthefollowingmedicalsocieties:AmericanCollegeofPhysiciansAmericanSocietyofInternalMedicine
Disclosure:Nothingtodisclose.
Coauthor(s)NajiaHuda,MDAssistantProfessor,WayneStateUniversitySchoolofMedicineDirectorofMICU,DivisionofPulmonaryandCriticalCare,DetroitReceivingHospital
NajiaHuda,MDisamemberofthefollowingmedicalsocieties:AmericanCollegeofChestPhysicians,AmericanThoracicSociety,andSocietyofCriticalCareMedicine
Disclosure:Nothingtodisclose.
ChiefEditorMichaelRPinsky,MD,CM,Drhc,FCCP,MCCMProfessorofCriticalCareMedicine,Bioengineering,CardiovascularDisease,ClinicalandTranslationalScienceandAnesthesiology,ViceChairofAcademicAffairs,DepartmentofCriticalCareMedicine,UniversityofPittsburghMedicalCenter,UniversityofPittsburghSchoolofMedicine
MichaelRPinsky,MD,CM,Drhc,FCCP,MCCMisamemberofthefollowingmedicalsocieties:AmericanCollegeofChestPhysicians,AmericanCollegeofCriticalCareMedicine,AmericanHeartAssociation,AmericanThoracicSociety,AssociationofUniversityAnesthetists,EuropeanSocietyofIntensiveCareMedicine,ShockSociety,andSocietyofCriticalCareMedicine
Disclosure:LiDCOLtdHonorariaConsultingiNTELOMEDIntellectualpropertyrightsBoardmembershipEdwardsLifesciencesHonorariaConsultingMasimo,IncHonorariaBoardmembership
AdditionalContributorsRyanCChang,MDConsultingStaff,DepartmentofInternalMedicine,DivisionsofPulmonaryandCriticalCare,KaiserPermanenteSanFrancisco
RyanCChang,MDisamemberofthefollowingmedicalsocieties:AmericanCollegeofChestPhysiciansandAmericanThoracicSociety
Disclosure:Nothingtodisclose.
OlehWasylHnatiuk,MDProgramDirector,NationalCapitalConsortium,PulmonaryandCriticalCare,WalterReedArmyMedicalCenterAssociateProfessor,DepartmentofMedicine,UniformedServicesUniversityofHealthSciences
OlehWasylHnatiuk,MDisamemberofthefollowingmedicalsocieties:AmericanCollegeofChestPhysicians,AmericanCollegeofPhysicians,andAmericanThoracicSociety
Disclosure:Nothingtodisclose.
FranciscoTalavera,PharmD,PhDAdjunctAssistantProfessor,UniversityofNebraskaMedicalCenterCollegeofPharmacyEditorinChief,MedscapeDrugReference
Disclosure:MedscapeReferenceSalaryEmployment
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