Neuroscience letters
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Neuroscience letters · Jul 1998
Increased capsaicin-induced secondary hyperalgesia as a marker of abnormal sensory activity in patients with fibromyalgia.
In this study, capsaicin-induced secondary hyperalgesia was assessed as a marker of abnormal nociceptive processing in patients with fibromyalgia (FM). The area of mechanical secondary hyperalgesia induced by a standard solution of capsaicin placed on the volar forearm was measured in ten patients with FM and the results compared to those obtained in ten patients with rheumatoid arthritis (RA) and ten normal subjects. ⋯ In the FM group the area of hyperalgesia correlated with the overall pain score and with the joint tenderness score. The results suggest that in FM there is enhanced sensitivity of nociceptive neurones at a spinal level, thereby supporting the concept of a generalised disturbance of pain modulation in this disorder.
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Neuroscience letters · Jul 1998
Crossed reduction of human motor cortex excitability by 1-Hz transcranial magnetic stimulation.
Electrophysiological studies have shown that 1-Hz repetitive transcranial magnetic stimulation (rTMS) of the primary motor area (M1) can produce a local decrease in excitability. Functional imaging data suggest that this change may be bilateral. ⋯ The slope of the curve relating MEP amplitude and stimulation intensity was decreased in the unstimulated hemisphere by active but not sham rTMS. This demonstrates that rTMS can condition cortical excitability at a distance of one or more synapses and suggest that decreased excitability to TMS is a correlate of decreased blood flow and metabolism.