Since the early 2000’s experiments gene therapy experiments have been done on rodents using a non-replicating (Not growing) version of Herpesvirus (cold sore virus). The virus’s genetic machinery has been altered so it makes ingredients for enkephalins (spine cord morphine-like produced agent) or similar. When injected into a painful nerve segment, the virus ascends to the spinal dorsal root ganglion where it alters the cells there to make pro-enkephalins leading to significant relief for 3-7 weeks. Now human trials are scheduled for China
Sheng Li Xue Bao. 2008 Oct 25;60(5):610-6.
HSV gene transfer in the treatment of chronic pain.
Fink DJ, Mata M. abstract
A good review of some of the research is here
They mention some of the results in animals. A nerve would be cut or ligated (string tight around) and the irritability of the limb would be recorded.
You can see the irritability returned after 8 weeks but was helped by a second shot
Comment – I have give Botox shots for irritability in both Trigeminal Neuralgia and shotting pains occipital neuralgia. Multiple intradermal (so superficial the skin blanches as injected) sites are used. It takes over a week to kick in and lasts 7-12 weeks. You have to plan ahead of time for the next shot or there will be an intervening pain period. I would use 100-200 units depending on where. That would come to $400-800 every 6 to 11 weeks. I suspect this virus treatment will be much the same – needing to be repeated every 6-7 weeks and costing a fortune each time. Still, is an advance where there can be little to offer for chronic radiculopathy anyway. discussed here