Ultrasonography, Doppler, TranscranialUltrasonography, DopplerBlood Flow VelocityCerebrovascular CirculationUltrasonography, Doppler, ColorUltrasonographyTranscranial Magnetic StimulationEchoencephalographyCerebral ArteriesMiddle Cerebral ArteryIntracranial Embolism and ThrombosisIntracranial PressureUltrasonography, Doppler, PulsedValsalva ManeuverBrain Hemorrhage, TraumaticCerebrovascular DisordersAnemia, Sickle CellHeart Septal Defects, AtrialArterial Occlusive DiseasesIntracranial EmbolismEvoked Potentials, MotorDoppler EffectIschemic Attack, TransientProspective StudiesCerebral AngiographyUltrasonography, PrenatalPulsatile FlowCarbon DioxideStrokeBrain IschemiaSensitivity and SpecificityBrainMotor CortexUltrasonography, Doppler, DuplexBlood PressureRegional Blood FlowEchocardiography, Doppler, PulsedCarotid StenosisReproducibility of ResultsEchocardiography, Doppler, ColorCarotid Artery, InternalPredictive Value of TestsMonitoring, IntraoperativeBasilar ArteryContrast MediaCircle of WillisUmbilical ArteriesEmbolism, AirTomography, X-Ray ComputedVascular ResistanceCarotid Artery DiseasesPregnancyOphthalmic ArteryUltrasonicsMagnetic Resonance ImagingEndarterectomy, CarotidHemodynamicsVertebral ArteryCerebral Arterial DiseasesMonitoring, PhysiologicFunctional LateralityTime FactorsPlacental CirculationVasospasm, IntracranialObserver VariationEmbolism, ParadoxicalScrotumReference ValuesSubclavian Steal SyndromeCollateral CirculationTreatment OutcomeAcetazolamidePortal VeinCarotid ArteriesAngiography, Digital SubtractionFetal DiseasesUltrasonography, InterventionalHypocapniaEndosonographyIntracranial Arterial DiseasesForamen Ovale, PatentTesticular DiseasesConstriction, PathologicPyramidal TractsSubarachnoid HemorrhageLaser-Doppler FlowmetryArteriesElectromyographyMagnetic Resonance AngiographyRetrospective StudiesFollow-Up StudiesIntracranial HypertensionSkullHepatic VeinsPhosphenesUterusElectric StimulationAcute DiseasePortographySeverity of Illness Index