The US team showed that regenerating nerve fibres can reform connections after being guided to the right targets.

Back and neck injuries often result in paralysis because, unlike peripheral nerves, the “wires” of the spinal cord do not naturally mend themselves.

Recently scientists have shown that the severed wires, called axons, can be made to regenerate into and beyond injury sites.

But, like the wires in a wall plug, nerve fibres have to be attached to the right places.

A key problem has been how to ensure regenerating fibres join up with their correct cell targets when faced with millions of potential alternatives.

Scientists conducting the new research at the University of California, San Diego, regenerated sensory axons in rats with spinal injuries.

They showed that the nerve fibres could be guided to their correct targets using a biological chemical that promotes growth.

The results of the research were published in the journal Nature Neuroscience.

Professor Mark Tuszynski, director of the university’s Centre for Neural Repair, said: “While our findings are very encouraging in this respect, they also highlight the complexity of restoring function in the injured spinal cord.”