Vertebrobasilar InsufficiencyVertebral ArteryBasilar ArteryCerebral AngiographyIntracranial AneurysmSubclavian ArteryVertebral Artery DissectionVertigoSubclavian Steal SyndromeMagnetic Resonance AngiographyAngiography, Digital SubtractionInfarction, Posterior Cerebral ArteryIschemic Attack, TransientIntracranial ArteriosclerosisPetrous BoneTrigeminal NeuralgiaEchoencephalographyAneurysm, DissectingCerebral Hemorrhage, TraumaticArterial Occlusive DiseasesIntracranial Embolism and ThrombosisTrochlear Nerve InjuriesPosterior Cerebral ArteryAngioplasty, BalloonLabyrinthitisTomography, X-Ray ComputedAngiographyCerebrovascular DisordersNerve Compression SyndromesStentsCerebral InfarctionHemifacial SpasmSubarachnoid HemorrhageSubarachnoid Hemorrhage, TraumaticTreatment OutcomeUltrasonography, Doppler, TranscranialConstriction, PathologicComaCerebrovascular CirculationMagnetic Resonance ImagingStrokeHeadacheTrigeminal NerveCerebellar DiseasesCircle of WillisBrain IschemiaOccipital BoneRetrospective StudiesAneurysm, RupturedFollow-Up StudiesBrain InfarctionTemporal BoneBrachiocephalic TrunkBlood Flow VelocityEmbolization, TherapeuticAngioplastyCarotid Artery, InternalDilatation, PathologicProspective StudiesThrombectomyInfusions, Intra-ArterialThrombolytic TherapyCerebellumHematomaCerebral RevascularizationBrain StemRecurrenceCarotid ArteriesCerebral HemorrhageSymptom AssessmentAcute DiseaseCerebral ArteriesDepressionImaging, Three-DimensionalFatal OutcomeCarotid StenosisTime FactorsCarotid Artery DiseasesRisk FactorsVascular Surgical ProceduresBlood Vessel ProsthesisUltrasonographyQuestionnairesFeasibility Studies