Spinal injury 'bypassed' by nerve

Doctors hope to use the body's own nerves to bridge the gap in the spinal cord left by paralysing injuries. Dr John Martin, from Columbia University, New York, took a nerve leaving the spine just above an injury, and reattached it below.

New Scientist magazine reports that rats used in the experiment showed some signs of renewed movement. A UK expert said the injury location could govern whether a suitable nerve was available for surgery.

An injury that breaks or severely damages the spinal cord can cause permanent disability, with the extent set by exactly how far down the spine the damage has happened. Scientists are hunting for ways to repair that damage, including using growth-promoting chemicals to encourage healing across the 'gap', and grafts of nerve fibres from elsewhere in the body.

The New York approach is slightly different - it takes one of the nerves that naturally leaves the spinal column, disconnects it from its destination, then plugs it back into the spinal cord using a protein "glue". In the case of the rats, this was a nerve heading for the abdominal muscles, which was taken just above a break in the spinal cord, and reattached below.

After just two weeks, it became clear that the new arrangement was working, with the nerve growing and starting to form connections with its new neighbour. Sending electrical impulses down the spinal cord caused twitching in the lower limbs, again indicating that connections had been made. There were no ill-effects in the abdominal muscle, as other nerves connected to it compensated for the loss of one connection.

Professor Marie Filbin, from Hunter College, New York, told New Scientist: "It's amazing that the nerve bridge makes functional synapses and regenerates to the state it does." She warned, however, that it might not be possible for the abdominal nerve to upgrade from its more modest job to take on the sophisticated role of the spinal cord.

Professor Giorgio Terenghi, from the University of Manchester, said that the approach was very interesting, and avoided some of the pitfalls of other nerve grafting techniques. "It's a very good idea, but the key thing is how much function they will be able to restore using this technique."

He said that another issue was that while the position of the spinal cord injury in the rats suited the use of the abdominal nerve, if the injury was elsewhere, higher or lower, there might not be a nerve that could be readily "sacrificed" to form the link without creating other problems. "You don't want to rob Peter to pay Paul," he said.