Epidural SpaceAnesthesia, EpiduralNeedlesInjections, EpiduralDura MaterSpinal CanalLigamentum FlavumAnalgesia, EpiduralLumbosacral RegionEpidural NeoplasmsLipomatosisRadiculopathySpinal Nerve RootsCoccyxLumbar VertebraeAnalgesia, ObstetricalThoracic VertebraeMyelographySpinal DiseasesTissue AdhesionsFiber Optic TechnologyAnesthesia, ObstetricalMathematical ConceptsIntracranial HypotensionLaminectomySpinal CordIntervertebral Disc DisplacementSpinal Cord CompressionFluoroscopyBlood Patch, EpiduralAnesthetics, LocalInjections, SpinalEpidural AbscessSpinal NeoplasmsAnesthesia, CaudalAnatomy, Cross-SectionalCatheterizationFentanylBupivacaineCervical VertebraeTomography, X-Ray ComputedSpinal Cord DiseasesEndoscopySpinal StenosisLow Back PainLidocaineMagnetic Resonance ImagingSteroidsPregnancy Trimester, ThirdNerve Block