Epidural SpaceSteroidsAnesthesia, EpiduralNeedlesInjections, EpiduralDura MaterSpinal CanalLigamentum FlavumAnalgesia, EpiduralLumbosacral RegionEpidural NeoplasmsRadiculopathyLipomatosisSpinal Nerve RootsLumbar VertebraeCoccyxAnalgesia, ObstetricalThoracic VertebraeMyelographySpinal DiseasesTissue AdhesionsFiber Optic TechnologyAnesthesia, ObstetricalMathematical ConceptsIntracranial HypotensionLaminectomySpinal CordIntervertebral Disc DisplacementFluoroscopySpinal Cord CompressionAnesthetics, LocalBlood Patch, EpiduralInjections, SpinalEpidural AbscessSpinal NeoplasmsGonadal Steroid HormonesAnesthesia, CaudalReceptors, SteroidAnatomy, Cross-SectionalCatheterizationFentanylBupivacaineCervical VertebraeTomography, X-Ray ComputedSpinal Cord DiseasesSpinal StenosisEndoscopyLow Back PainLidocaineMagnetic Resonance ImagingPregnancy Trimester, ThirdNerve Block