Incidence of the reported pain to pinprick stimuli on the back and palmar and dorsal aspects of the hand. Incidence of reported pain is shown as a function of the pinprick stimulus force A. at the back (triangles), B. hand palmar (circles), and C. the dorsum of the hand (circles). Filled symbols: patients with chronic low back pain (CLBP), open symbols: healthy controls (HC). Population threshold (force at which 50% of pinprick stimuli were reported to be painful): dotted line in A, B and D. Asterisks in A, B, C depict significant differences (P < 0.05) between groups in the incidence of reported pain.
Puta et al. BMC Neurology 2012 12:98 doi:10.1186/1471-2377-12-98