The acute administration of hydrophilic polymers (polyethylene glycol) can immediately seal nerve membranes, preventing their continuing dissolution and secondary axotomy. Polymer application can even be used to reconnect, or fuse, the proximal and distal segments of severed axons in completely transected adult mammalian spinal cord. The sealing or fusion of damaged nerve membranes leads to a very rapid (minutes or hours) recovery of excitability in severely damaged nerve fibers, observed as a rapid return of nerve impulse conduction in vitro, as well as an in vivo recovery of spinal cord conduction and behavioral loss in spinal cord-injured adult guinea pigs. Surfactant application produces a rapid repair of membrane breaches through mechanisms of interaction between the polymers and the aqueous phase of damaged membranes, and their ability to insert into, or seal, the hydrophobic core of the axolemma exposed by mechanical damage. This new technology applied to severe neurotrauma offers a clinically safe and practical means to rescue significant populations of spinal cord nerve fibers within 8 hours after damage--preventing their continued dissolution and secondary axotomy by secondary injury mechanisms. Application of this novel technology to other injuries to the peripheral and central nervous system is discussed, as well as a general application to soft tissue trauma.