Could Gabapentin And Oxycodone Helps In Relieving The Pain Due To Neuropathy?

my wife has being diagnosed to have neuropathy( severe pain in her upper jaw).She has had many surgerys on her teeth and her pain tallerance is very low. One of the top surgeons here in XXXX ruled out trgeminal neuralgia.He told her it was neuropathy and her only hope was the pain clinic with drugs to give her relief .Two years ago she had this and the drug gabapentin 600 mg twice daily gave her total relief.She is now on 2400 gm.per day and Oxycodone (5/325mg).They are not getting to the pain now.She has tried Carbamazepine ,Baclofen,Oxcarbazepine,and others with no success.