InfarctionSpinal CordParaparesisSpinal Cord IschemiaSpinal Cord InjuriesParaplegiaCervical VertebraeMagnetic Resonance ImagingSpinal Cord CompressionSpinal Cord DiseasesQuadriplegiaSpinal Cord NeoplasmsSpinal CanalPhrenic NerveMyelitisForelimbMyocardial InfarctionAnterior Horn CellsMyelographyLaminectomyParalysisRecovery of FunctionMotor NeuronsSpinal InjuriesNeckContusionsCerebral InfarctionRespiratory ParalysisSpondylosisSpinal Nerve RootsPyramidal TractsSpinal Cord StimulationRats, Sprague-DawleyKlippel-Feil SyndromeRed NucleusNeck InjuriesEcho-Planar ImagingTime FactorsNerve TissueAxonsNerve RegenerationElectric Stimulation Therapy