A revolutionary electrical implant may be able to stimulate the regrowth of nerves severed in devastating spinal injuries.

The first human trials of the US-developed device, called Traxon, are about to begin at a hospital in Dublin.

The neurosurgeon leading the study says that in previous experiments, dogs have some restored movement in their lower bodies and many regain control over their bladders.

An implant stimulates nerve growth

He is hopeful that even if human patients cannot re-achieve full movement and sensation, they could at least gain these benefits.

The implant works on the principle that nerves can be encouraged to grow faster and in a particular direction if an electrical current is passed through them.

When the spinal cord is severed in an accident the nerves do try to re-grow, but often in a haphazard way, in random directions, with the effect that very few new connections are ever made.

The device involves inserting two electrodes near the site of the spinal injury, with wires leading away to a palm-sized battery pack which sits in the soft tissue of the abdomen.

Unknown territory

A very low power electrical field - unfelt by the patient - is generated for up to a year.

Mr Ciaran Bolger, director of neurosurgery at Beaumont Hospital in Dublin, says he is excited about the potential benefits to patients.

He said: "The technology is similar to that used in a cardiac pacemaker, except it produces this very gentle electric field all the time.

"It has been tested on rats, cats and dogs, and there has been recovery of bladder function, and perhaps some sexual function.

Spinal injuries require intense therapy

"Some of the dogs did get some movement of limbs."

He added: "I don't know what's going to happen in humans. Even if they get back some bladder function, that is very important if you are paralysed from the neck down."

Currently there is little that can be done for patients with severe spinal injuries, although approximately one in ten does eventually get some movement back.

Mr Bolger is now awaiting the first suitable patient to arrive at the Beaumont.

"Because this is the first time it has been tried in humans, it can only be used in the most severe cases - those who can't be helped any other way," he said.

The device has been developed in the US by a company called Dynamed Systems.