Botox for nerve pain

Botox appears to be effective for peripheral nerve pain according to a study by French researchers.  This finding is consistent with my observation that injecting Botox into the skin of the top of the head in patients with headaches relieves pain in that area.  When I started injecting botulinum toxin (Botox) for headaches about 15 years ago the assumption was that Botox works by relieving spasm of muscles in the forehead, temples, back of the head, and neck.  However, some patients would come back and report that their headache was gone in the injected areas, but not on the top of the head.  When gave additional injections the top of the head pain also stopped.  I also see patients who get Botox injections for their headaches from dermatologists or plastic surgeons and do not obtain adequate relief.  This is usually because only the front of the head is injected, rather then all areas of pain.   There have been other reports of Botox relieving pain of diabetic as well as trigeminal neuralgia, however the French group conducted a very rigorous double-blind study which provides scientific proof of pain-relieving properties of Botox.