Many thanks for your reply and the web sites which were very informative.
The axon damage occurred before he had chemotherapy and was described as chronic illness syndrome (UK). The neurologist said that the tests showed only a shadow where the axons had been. I don't know if this means the nerve cells are all dead. At one time he couldn't speak or swallow, but that has come back now. He says his feet feel cold, but to the touch they are warm. He now has a nasty case of shingles on his head and neck.
As a gardener I pinch out the growing tips of plants to make them bush out. I am hoping the nerves will regrow from the beginning of the damage, and from what you said, it sounds as though that might happen. I know that this can occur with blood vessels that compensate for blockages by putting out capilleries around the blockage.
Again many thanks for your help. Best wishes Sally in UK