Since I have heard things similar to this before (opioids helping PN/neuropathic pain), and at least 3 times during the past week here on NT, I did a little poking around.

I googled: peripheral neuropathy treatment opioid. The question of opioid pain medications for PN seems to be somewhat nebulous. Many sites list "painkillers" as treatment options without specifying what types, so that may be open to interpretation. Some links cite studies that support opioid therapy for neuropathic pain, others argue both ways, and some dance around it with statements like:
without coming out and saying that opioids are an effective treatment.

It may be that the doctors are as confused as the rest of us. Science has been known to change its positions before, and maybe there's more that needs to be learned about pain and its treatment.

In the meantime, for those patients whose doctors are changing/cutting their pain meds to their detriment, I would hope it couldn't hurt to search out and glean some of the studies/articles supporting what they already know to be true, and discuss them with their doctors. If the evidence is not persuassive, they may at least get some better answers.

Doc