The Clinical journal of pain
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The nociceptive flexion reflex (NFR) is a spinal reflex induced by painful stimuli resulting in a withdrawal response. Research has shown that the NFR is inhibited through endogenous pain inhibitory mechanisms, which can be assessed by conditioned pain modulation (CPM) paradigms. Although accumulating research suggests that the NFR can be affected by CPM, no clear overview of the current evidence exists. Therefore, the present review aimed at providing such a synthesis of the literature. In addition, the influence of personal factors on the CPM of the NFR was investigated. ⋯ The present review demonstrates that certain types of nociceptive conditioning stimuli have the potential to depress, at the spinal level, nociceptive stimuli elicited from distant body regions. Although CPM of the NFR seems to be robust to the influence of several personal factors, it can be affected by cognitive influences.