Liz Buchanan BVSc MRCVS
Possible causes for itchy patches of ulceration on the back of the neck that look like this, include fleas, allergies, flea allergies, mites, eg demodex, trauma, hypersensitivity, autoimmune disease, neurological abnormalities and epilepsy. Usually a vet will rule these out as far as possible before either referring to an expert / dermatologist, or trying to treat the symptoms. I have heard of acupuncture being successful in some cases, but because a variety of causes may be implicated in cases that answer the description, responses can vary. I hope that your vet can work systematically with you and your cat to find a response.