Epidural SpaceAnesthesia, EpiduralNeedlesInjections, EpiduralDura MaterSpinal CanalLow Back PainLigamentum FlavumLumbosacral RegionAnalgesia, EpiduralBack PainEpidural NeoplasmsBackLumbar VertebraeRadiculopathyLipomatosisSpinal Nerve RootsCoccyxAnalgesia, ObstetricalThoracic VertebraeSpinal DiseasesMyelographyTissue AdhesionsAnesthesia, ObstetricalFiber Optic TechnologyLaminectomyMathematical ConceptsIntracranial HypotensionSpinal CordSpinal Cord CompressionFluoroscopyIntervertebral Disc DisplacementAnesthetics, LocalEpidural AbscessInjections, SpinalSpinal NeoplasmsBlood Patch, EpiduralAnesthesia, CaudalAnatomy, Cross-SectionalCatheterizationFentanylCervical VertebraeBupivacaineTomography, X-Ray ComputedMagnetic Resonance ImagingEndoscopySpinal Cord DiseasesSpinal StenosisLidocaineSteroidsBack InjuriesNerve BlockPregnancy Trimester, Third