Figure 1

Pain ratings and treatment effects on pain. A. An example of pain ratings in CBP and OA. CBP patients rated spontaneous fluctuations in their pain intensity in the absence of an overt experimental stimulus (top). OA patients rated the fluctuations in their pain intensity in response to a pressure stimulus (gray) applied on the affected knee. B. CBP patients exhibited a significant decrease in pain after 2 weeks of topical Lidocaine treatment as measured by VAS (p < 0.01) and average pain during the scan (p < 0.05) (right bar graphs). OA patients did not show any decrease in pain after treatment as measured by VAS (p = 0.5), and a borderline decrease in pain in response to pressure stimulation (computed as average pain during scan divided by average pressure in standardized units) (p = 0.06) (left bar graphs). Error bars are standard deviations.