European journal of pain : EJP
-
Two studies are reported that tested the fear-avoidance (FA) model using path analytic techniques. In study 1, 429 employees with back pain at baseline and back pain at 18 months follow-up completed questionnaires assessing sociodemographic information, pain severity, negative affect, pain-related fear, and disability. Results indicated that pain severity at baseline predicted pain-related fear and disability at follow-up, and that pain-related fear is rather a consequence than an antecedent of pain severity. ⋯ A similar model as in study 1 was tested. Overall, results are in line with those of study 1. Results are discussed in terms of theoretical relevance and clinical implications.
-
Central sensitization is believed to be one of the key mechanisms behind chronic pain conditions, and several models have been developed in order to characterize this phenomenon in humans. One of these models relies on conditioning electrical stimulation to elicit long-lasting effects on the nociceptive system. The aim of this study was to evaluate these effects using an objective electrophysiological measurement, the nociceptive withdrawal reflex (NWR). ⋯ To evaluate the excitability of the nociceptive system, the NWR was elicited within the same innervation area (superficial peroneal nerve) at graded stimulation intensities and recorded in the hamstrings. Following low-frequency stimulation, an intensity-independent long-lasting facilitation of the NWR was observed, with a significant increase in the reflex size (average of 31+/-4%, p<0.001) and in the number of reflexes (average increase of 22+/-10%, p<0.01), accompanied by a significant increase in the blood flow (average increase of 40+/-10%, p<0.001). These findings suggest that activity-dependent central sensitization can be elicited using conditioning electrical stimulation with a stimulation frequency that lies within the physiological firing range of primary afferents, and that it can be objectively assessed in humans using the NWR.