Extradural-to-intradural transfer of spinal nerves to sacral roots.24, 27, 30. a | After extradural transection of the L1 nerve in its IVF, the nerve is moved back into the dural sac and sutured to the proximal ends of S3 and S4 dorsal and ventral roots. b | T12 nerves are extradurally transected, moved intradurally and anastomosed end-to-end to S2 and S3 ventral and dorsal roots, using a silicone elastomer filter formed into a tube and secured with silver clips. c | Extradurally neurolysed T11 and T12 nerves are reintroduced into the vertebral canal at the upper sacral level and aligned to S2 and S3 ventral roots, using a polymeric film secured with biological glue. Abbreviations: CG, coccygeal; IVF, intervertebral foramen; L, lumbar; S, sacral; T, thoracic.