344 © 2018 Journal of Neurosciences in Rural Practice | Published by Wolters Kluwer - Medknow

Aim: To prospectively study the clinical profile, angiographic features, andfunctional outcomes, in consecutive cases of extracranial dissection seen at twotertiary stroke care centers in South India. Materials and Methods: In thisobservational study, spanning 4 years (December 12–December 16), a total of442patientspresentedwithanacuteischemicstroke/transientischemicattack(TIA)at our study centers. 14/546 (3.2%) of these patients had magnetic resonanceangiography (MRA)/computed tomography angiography (CTA) evidence ofextracranialdissections.Allcasesunderwentdetailedclinicalevaluationonarrival,and data were recorded on a predesigned stroke pro forma. Contrast MRA wasdoneonarrivalinallcasesaspartofastandardstrokeprotocol,andCTAwasdoneonlyifMRAwasinconclusive.Thepatternofthevesselinvolvedandmorphologyof vessel dissection was analyzed as per a standard radiology protocol. All thecases were managed with short‑term anticoagulation using low‑molecular‑weightheparin followed by oral anticoagulants for 3–6months.All caseswere followedup for 1–2 years and the functional outcomes were recorded using the modifiedRankinScale(mRS).Results: Therewere11malesand3femalesinthestudy,andthemeanagewas45.1years(range=27–65years).Focalneurologicalsymptomsoccurred in all these patients (10 patients had a stroke, and 4 had TIA). Nearly64.2%of these (9/14)were stroke inyoung (age<45years).The internal carotidarterywas themost common vessel involved in 85.7% (12/14) cases.Of the tenpatientswithcompletedstroke,agoodfunctionaloutcome(mRS1–2)wasseenin8/10(80%).Digitalsubtractionangiographyandrevascularizationprocedureswereneededonly in aminorityof cases3/14 (21%).\Conclusion: Thishospital‑basedstudyhighlights the importanceofsuspectingarterialdissections inyoungstrokesof unexplained etiology, and offering optimumanticoagulant therapy in the acutephase,toachievegoodlong‑termoutcomes.

Keywords: Angiography, cerebral dissections, heparin

A Study on the Clinical and Angiographic Spectrum of Spontaneous Extracranial Dissections in the Cerebral VasculatureRavi K. Anadure, Aneesh Mohimen1, Rajeev Saxena1, Rajeev Sivasankar2

cerebralarteriesaffectallagegroups,includingchildren,but there isadistinctpeak in thefifthdecadeof life.[3,4]Dissections of the carotid and vertebral arteries usuallyarise from an intimal tear. The tear allows blood underarterialpressure toenter thewallof thearteryandform

Original Article

Introduction

Arterialdissectionisanincreasinglyrecognizedcauseof stroke, which accounts for up to 10%–25% of

ischemic strokes in young adults.[1,2] Cerebral vesseldissections lead to cerebral ischemia due to eitherartery‑to‑artery embolism or due to hemodynamicfailure. It was understood only in the late 1970s whenFisher et al.[1] and Mokri et al.[2] described dissectionsof carotid and vertebral arteries as detected by moderndiagnostic approaches. Spontaneous dissections of the

DepartmentsofMedicineand1Radiology,CommandHospitalAirForce,Bengaluru,Karnataka,2DepartmentofRadiology,INHSAsvini,Mumbai,Maharashtra,India

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DOI: 10.4103/jnrp.jnrp_540_17

Address for correspondence: Col. Dr. Ravi K. Anadure, Department of Medicine, Command Hospital Air Force,

Agram Post, Bengaluru ‑ 560 007, Karnataka, India. E‑mail: ravi.anadure@gmail.com

How to cite this article: Anadure RK, Mohimen A, Saxena R, Sivasankar R. A study on the clinical and angiographic spectrum of spontaneous extracranial dissections in the cerebral vasculature. J Neurosci Rural Pract 2018;9:344-9.

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Published online: 2019-09-02

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an intramural hematoma, the so‑called false lumen.[5]Asubintimal dissection tends to result in stenosis of thearterial lumen,whereasa sub‑adventitialdissectionmaycause aneurysmal dilatation of the artery, often referredtoas“pseudoaneurysms.”Whileoccasionalcase reportsand small case series exist on this subject, there is apaucityofliteraturefromourcountry.Wethusundertooka systematic prospective study of angiographicallyconfirmed cases of spontaneous extracranial cerebraldissection, to bring out their wide clinical spectrumand pattern of vessel involvement along with clinicaloutcomes.

Materials and MethodsThis prospective observational study was carried outat the Departments of Neurology and Radiology atINHS Asvini, Mumbai and Command Hospital AirForce, Bengaluru. These are tertiary referral centersof the Armed Forces, with state‑of‑the‑art dedicatedstroke set up, including 1.5 Tesla magnetic resonanceimaging (MRI), 16 Slice multidetector computerizedtomography,andadigitalsubtractionangiography(DSA)laboratory, and get referrals from the southernand western regions of India. All cases underwentan MRI brain with contrast magnetic resonanceangiography (MRA), as a part of standard strokeprotocol.Where ever dissections were not conclusivelyestablished on contrast MRA, a computed tomographyangiography (CTA)was inadditiondone toconfirm thediagnosisanddefinetheculpritvessel.Thecasefilesandneuroimagingofpatientswithangiographically(contrastMRA/CTA) proven spontaneous cerebral dissectionwere preserved and analyzed, for the period coveringDecember12toDecember16.Thediagnosisofcerebraldissection was made based on standard clinical andneuroradiologic criteria, i.e., sudden onset of ischemicor hemorrhagic symptoms; MRI of brain consistentwith clinical symptoms; and angiographic findingscharacteristicofarterialdissection,suchasdoublelumensign (the presence of a false lumen or an intimal flap),intra‑mural hematoma (in vessel wall), stenosis (stringsign or tapered narrowing), stenosiswith dilation (pearland string sign), smoothly tapered occlusion (flamesign), and complex pseudoaneurysm formation. Patientswith histories of head trauma or cranial surgery within6monthsbeforeonsetwereexcludedfromthestudy.

The following radiologic and clinical parameterswere evaluated and compared: type of onset, vascularrisk factors, neuroimaging features, angiographicfindings, management strategy, and clinical outcome(by modified Rankin Scale [mRS]). A standard strokeMR protocol (T1, T2, fluid‑attenuated inversion

recovery,diffusionwithADCMapsandGradientEcho)was followed in all cases on a 1.5 Tesla SeimensMRImachine. Neurovascular imaging by contrast MRAwas performed within 24–72 h of onset in all cases.Contrast‑enhancedMRAwasdonewithdynamiccoronalsequences, including the aortic arch to cranial vault,after intravenous injection of gadolinium chelate at0.2 mmol/kg body weight. Manual scan triggering wasdoneoncecontrastwasnotedintheproximalaorta.CTAwasperformedin6of thesecaseswithin3–5daysafterthestroke,sinceMRAwasnotconclusivefordissectionin these cases. CTA was done after bolus injection ofnonionic contrast (1.5 ml/kg body weight) at the rateof 4ml/s. The acquisitionwas timed by bolus trackingtechnique with the trigger set in the ascending aorta.Caudocranial acquisition from the aortic arch to thecranialvaultwasobtainedafterminimumpostthresholddelay. Therapeutic DSA for mechanical thrombectomyorstentingwasperformedusingaSiemensPolystarTopmachine atMumbai and FD 10 PhilipsAlluramachineatBengaluru.

ResultsA total of 546 MRA were done at the two institutesduring the study period of 4 years (December 12 toDecember 16). Of these, 442 cases had an ischemicstroke/transient ischemic attack (TIA) as the clinicaland radiological presentation, and 104 had hemorrhagicpresentations (subarachnoid hemorrhage [SAH] orintracranial[IC]bleeds).Intheischemicsubsetofcases,14/442 (3.2%) were diagnosed with cervico‑vertebraldissection (extracranial). In the hemorrhagic subset,4/104 (3.8%) had IC dissection.Major differences existbetween dissections involving the IC and extracranialcervical‑cephalic arteries. The plane of dissection inthe cervical internal carotid artery (ICA) or vertebralartery (VA) isusuallywithin themedia.[6] Intracranially,the media is significantly simplified, and dissectionsof IC arteries are usually subintimal but may extendoutward through the adventitia resulting in SAH. We,therefore,focusedandselectivelyanalyzedthesubsetof14extracranialdissectionsonly[Table1].

In this study, out of 546 patients presenting with anacute stroke/TIA, we had 14 patients (14/546, 2.56%)with MRA/CTA evidence of extracranial dissections,seen over a span of 4 years. Further, these constituted3.2% (14/442) of all ischemic strokes. Focalneurological symptoms occurred in almost all thesepatients (10 patients had a stroke, and four had TIAs).The common carotid was involved in only one casewith double lumen sign on angiogram in the bulbregion [Figure 1] and distal M3 segment embolism on

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thesameside.Theangiographic featuresof the12ICAsinvolved by dissection were “flame‑shaped” narrowingwith “cutoff” in five cases [Figure 2], stenosis (usuallyan elongated irregular segment) in three [Figure 3a], anintimal flap in one, and pseudoaneurysm formation inthree.TheonlyVAinvolvedbyextracranialdissectiononangiographyshowedstenosiswithdistalocclusionin theV3 segment and left posterior inferior cerebellar arteryinfarct on MRI [Figure 4]. Follow‑up angiograms wereavailableonly in4/12 left internal carotid artery (LICA)dissectionsatvaryingperiods(8–12months)andshowedcompleterecanalizationinone,partialrecanalizationwithan irregular lumen in two and a chronic total occlusionwithgoodcollateralsintheremainingone.

All these patients were treated with anticoagulantsin the acute phase of the dissection (1–2 weeks)

and subsequently kept on long‑term anti‑plateletsfor stroke prophylaxis. Only those patients who haddisablingembolicstroke inwindowperiodor remainedsymptomatic with recurrent TIA or fresh strokes,despite optimizedmedicalmanagement, weremanagedwith endovascular intervention. One patient withLICA dissection and embolism to left middle cerebralartery (MCA) in the hospital [Figure 3b], underwent asuccessful mechanical thrombectomy with a SolitaireStentriever [Figure 3c], and made a good clinicalrecovery (mRS‑1). Two patients in this study grouphad recurrent TIA of the anterior circulation despiteoptimal medical therapy and underwent stenting ofthe stenosed vessel. One had a common carotid arterydisease and other an ICA (C1) segment dissection.All three cases had a favorable outcome with nearcomplete remodeling of the diseased vessel segmenton angiogram.Therewere noprocedural complicationsnoted. Follow‑up in this entire group ranged from 1 to2 years and no mortality was associated with cervicalarterial dissections. Of the 10 patients with completed

Table 1: Clinical features and radiological findings in 14 cases of extra‑cranial cervical dissectionCase number age/sex Presentation Site of lesion Angiographic findings Outcome (mRS)1 35/female Hemiparesis LICA(C1) Fl,RICAocclusion 32 27/male Vertigo,ataxia RVA(V2) S,RVAocclusion 23 53/male Neckpain,H,dysarthria RICA(C1) D,re‑canalized,irregular 14 35/male Hemiparesis,aphasia LICA(C1) P,re‑canalized,irregular 25 43/female Hemiparesis,aphasia LICA(C1) Fl,LICAocclusion 26 44/male Hemiparesis,aphasia LICA(C1) S+D+P,LMCAocclusion 37 35/male Neckpain,H,monoparesis RICA(C1) D+P,normalflow 18 44/male Hemiparesis LICA(C1) D,re‑canalized 19 62/female AphasicTIA LICA(C1) Fl,LICAocclusion 110 47/male AmnesticTIA(TGA) LICA(origin) Fl,LICAocclusion 111 65/male Hemiparesis,aphasia LICA(C1) Fl,LICAocclusion 212 43/male Hemiparesis,H,aphasia LCCA S+DL,80%stenosis 213 50/male RecurrentMCATIA LICA(origin) S+D,90%stenosis 114 49/male HemipareticTIA RICA(origin) S+D,70%stenosis 1H:Headache,Fl:Flame‑shapedtapering,S:Stenosiswithoutdilation,S+D:Stenosiswithdilation,D:Dilated,DL:Doublelumensign,P:Pseudoaneurysm,LICA:Leftinternalcarotidartery,RICA:Rightinternalcarotidartery,CCA:Commoncarotidartery,RVA:Rightvertebralartery,LMCA:Leftmiddlecerebralartery,TIA:Transientischemicattack,LCCA:LeftCCA,TGA:Transientglobalamnesia

Figure 1:Digitalsubtractionangiography leftcommoncarotidarteryinjection:SpontaneousdissectionofLeftcarotidbulbwithafillingdefectanddoublelumensign

Figure 2: Computed tomography angiogrammaximum intensityprojection(a)andvolumerendering(b)showingflameshapedtaperingoftherightinternalcarotidarterydistaltothecarotidbulbwithdistalembolicinfarcts(c)inrightmiddlecerebralarteryterritoryondiffusionmagneticresonanceimaging

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stroke, two had near complete recovery (mRS‑1), andfive had a mild residual neurologic deficit (mRS‑2).Only two patients had a significant deficit impairingactivities of daily living (mRS‑3). Headache atpresentation was noted in only 3/14 cases (21%).Essential hypertension was noted in 4/14 (28.5%),diabetesin3/14(21%),and6/14(42.8%)weresmokersin this studygroup.Optimizationofmedical therapy inthesepatientsneededtightbloodpressureandglycemiccontrol and smoking cessation measures. None of thepatients had a history ofmigraine headaches or use oforalcontraceptives.

DiscussionSpontaneous dissections of the carotid or VA accountfor only about 2% of all ischemic strokes,[6] but theyare an important cause of ischemic stroke in young andmiddle‑aged patients and account for 10%–25% of suchcases.[7]Overall,theextracranialICAisthemostfrequentlyaffected vessel, as was the finding in this study (12/14).In a population‑based study from Rochester, Minnesota,the annual incidence of spontaneous dissections of thecervicalICAforallageswas2.5/100,000.[8]

Themanagementof cervico‑cephalic arterialdissectionsremains a controversial issue. Our patients receiveda standardized treatment, with low‑molecular‑weightheparin in the acute phase and dual antiplatelets for3–6 months. Most, but not all, focal cerebral ischemicsymptoms associated with cervical arterial dissectionsare presumed to be thrombo‑embolic in origin.Therefore,acourseofanticoagulationtherapyisusuallyrecommended in patients with ischemic symptoms inthe absence of intra‑cranial hemorrhage or an alreadycompleted major infarct. In Intra‑cranial arterialdissections, a hemodynamic mechanism due to luminalnarrowingmay be as important as embolic phenomena.Furthermore, some patients with intra‑cranialarterial dissections may develop a SAH. Therefore,

anti‑coagulation therapy for this group of patients maycallforcaution.

Spontaneous cervical arterial dissections are generallyassociated with good clinical recovery. This probablyis due to a higher index of suspicion and improveddiagnostic methods allowing early diagnosis andtreatment. In adults with spontaneous extracranialcervico‑cephalic dissection, the rate of recurrentdissection during the 1st month is 2%, but from thattime on, it is approximately 1% per year and inverselyrelated to age.[3] Surgical intervention and repair orendovascular remodeling of the aneurysm are generallyreserved forpatientswithaSAHdue toan intra‑cranialdissecting aneurysm or for those with an extracranialresidualdissectinganeurysmthatcontains thrombusandcausescerebralembolizationandsymptomsof recurrentischemia.1/14inthisstudyhadanembolicocclusionofMCA in the acute phase of stroke and benefitted froma thrombectomy. 2/14 patients in this study group hadrecurrent TIA/stroke despite optimum medical therapyandunderwent stentingof the stenosedvessel.All threehadafavorableoutcomewithnearcompleteremodelingof the diseased vessel segment on angiogram.Extracranial‑Intra‑cranial arterial bypass operationsmayoccasionally be justified for patientswith hemodynamiccerebral ischemic symptoms caused by proximal vesselstenosisorocclusion,butthisindicationisrare.Thepathogenesisofarterialdissectionsisnotclearinallcases.Mechanicalfactorsandanunderlyingarteriopathyhave been blamed.[9,10] History of a trivial and oftendoubtful trauma is frequent, understandablymore so inchildren than in adults. A predisposing disorder of thearterialwall, although suspected, cannotbedocumentedin most patients. There are reported associations ofspontaneous cervico‑cephalic arterial dissections withfibromuscular dysplasia, cystic medial necrosis,Marfan

Figure 4:Contrastenhanced‑magneticresonanceangiographycoronalimagesshowrightvertebralarterydissection(singlearrow)nearoriginwithdiffusenarrowingandcutoffinV2segment(doublearrow).Normalleftvertebralartery(redarrow)isclearlyseen.AxialT2weightedimageshowingacuterightposteriorinferiorcerebellararteryterritoryinfarctsdue to distal extension of dissection to involve the posterior inferiorcerebellararterybranchfromV4segmentofrightvertebralartery

Figure 3:Digitalsubtractionangiography leftcommoncarotidarteryinjection:(a).Leftinternalcarotidarteryorigindissectionwithdiffusestenosisofinternalcarotidarteryandcompleteexternalcarotidarterycutoffonthesameside(b).DistalembolismtoleftmiddlecerebralarterywithcompleteM1cutoffintheintra‑cranialview(c).Re‑canalizationofleftmiddlecerebralarteryafterthrombectomywithsolitairestentriever

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syndrome, Ehlers–Danlos.[11‑13] In the present study, nosuch risk factors or collagenosis could be identifiedclinicallyorangiographically.

Noninvasive vascular imaging (CT/MRA) ismandatoryintheevaluationofallformsofcranio‑cerberalischemiaandoneor a combinationof bothmodalities suffices inclinching the diagnosis. The characteristic angiographicfinding is a long segment tapering or occlusion ofthe cervical ICA with typical sparing of the carotidbulb (distinguishing feature from an atheroscleroticocclusion).[14] The classic intimal flap is diagnostic,but variably seen. Evaluation of the major collateralsacross the Circle of Willis helps to prognosticate theextent of likely hemodynamic cerebral compromise,and also serves to plan an endovascular interventionif needed. Intramural hematoma is less often seen in aVA dissection and the diagnosis should be suspectedwith observation of an increased vessel diameter andcrescentic mural thickening.[15] High resolution vesselwall MRI can elegantly demonstrate the intra‑muralhematomaanddistinguish it froma lipid‑richplaque, incases where a diagnostic dilemma still exists after CT/MRA.[16]

The reported rate of death from dissections of thecarotid and vertebral arteries is <5%, and aboutthree‑fourths of patients who have had a stroke makea good functional recovery.[17] Headache associatedwith dissection resolves within a week in about 90%of patients, but in a few patients, it can persist formany years.[18] The follow‑up in this study groupranged from 1 to 2 years, and no mortality wasassociated with cervical arterial dissections. Of the10 patients with completed stroke, three had a nearcomplete recovery (mRS‑1) and five had a mildresidualneurologicdeficit (mRS‑2).Thesefindingsareconsistent with the findings from previous studies onthissubject.[17]

Dissection of the carotid and vertebral arteries is adynamic processes. The radiographic findings maychange dramatically within a period of days or evenhours.Althoughtheradiographicappearancemayworsenduring the acute phase of dissection, about 90% ofstenosis eventually resolve.[15] Two‑thirds of occlusionsare recanalized, and one‑third of aneurysms decrease insize over 3–6 months.[19] Follow‑up angiograms wereavailableonly in4/14LICAdissections in this study,atvarying periods of 8–12 months, and showed completere‑canalization in one, partial re‑canalization withirregular lumen in two and a chronic total occlusionwithgoodcollaterals in the remainingone.This reflectsthe dynamic nature of dissections as noted in previousstudies.[20]

ConclusionInthisprospectiveobservationalstudy,spanning4years,the prevalence of extracranial dissections in ischemicstroke subsetwas 3.2% (14/442). 64.2% of these (9/14)were stroke in young (age <45 years), suggestingdissections as an important cause of young strokes,whichrequiresahighindexofsuspicion,andspecialMRsequences/CTA.Therapywith short‑termanticoagulationseems safe and effective with no mortality in thisstudy and good functional outcomes (based on mRS1–2) in 12/14 (86%) cases. DSA and revascularizationprocedures like thrombectomy/stenting were neededonly in a minority of cases 21% (3/14) who either hadwindow period embolic strokes or persistent symptomsdespite optimum medical therapy. Unlike Westernstudies, arteriopathies and collagenosis are rare in anIndian population, and no such cases were identifiedin this study. Most cases of extracranial dissections inour population are probably still related to prematureatherosclerosisortrivialtrauma(oftennotreported).ThisIndian hospital‑based study highlights the importance ofsuspecting dissections in young strokes of unexplainedetiology, and offering optimum therapy in the acutephase,toachievegoodlong‑termfunctionaloutcomes.

Financial support and sponsorshipNil.

Conflicts of interestTherearenoconflictsofinterest.

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