Lidocaine is a sodium channel blocking agent.

It stops nerve impulses and this how it works to numb pain.

I have had huge success with these patches over the years.

What does happen however, is that some insurances will not pay for them, unless you have a prior diagnosis of shingles.

But then if you are denied, your doctor can appeal that with medical need by fax to your carrier. It might work in your favor.

http://www.ncbi.nlm.nih.gov/pubmed/16178759

One needs to be patient with these patches as they don't work instantly...it may be a day 2 or 3 days to show benefit.
Also you have to place them carefully. I find looking at an anatomy book with nerve pathways, helps. Putting them on the endpoints of pain, works less, than on the pathway of the nerve axon.

I place 1/2 patch on the tops of my feet therefore for burning foot pain. 1/2 patch behind the knee sometimes, and when I had the terrible MP neuropathy I used 1/2 patch in 2 areas at the top of the thigh... in 2 weeks the nerve stopped firing, and I was in a remission! (lateral femoral nerve).

I think doctors who deny this potential treatment do so because they don't understand it or how to effect success with it.