Because the blood flow (and therefore the heat emitted from) the skin is controlled by the nervous system, digital infrared thermal imaging provides an ideal way to find the cause and extent of neurological problems, including pain syndromes and numbness.
Here is a collection of images so you can see samples of what will turn up with digital infrared thermal imaging.

All measurements made show that nerve root problems can be detected thermographically, although some vascular diseases can mask it.

-Thermography In Nerve Root Diseases