Pain
-
Randomized Controlled Trial
A PET activation study of brush-evoked allodynia in patients with nerve injury pain.
Acute experimental brush-evoked allodynia induces a cortical activation pattern that differs from that typically seen during experimental nociceptive pain. In this study, we used positron emission tomography to measure changes in regional cerebral blood flow (rCBF) in patients with clinical allodynia. Nine patients with peripheral nerve injury were scanned during rest, brush-evoked allodynia, and brushing of normal contralateral skin. ⋯ A direct post hoc comparison of brush -and allodynia-induced rCBF changes showed that allodynia was associated with significantly stronger activations in orbitofrontal cortex and ipsilateral insula whereas non-painful brushing more strongly activated SI and BA 5/7. These findings indicate that activity in the cortical network involved in the sensory-discriminative processing of nociceptive pain is downregulated in neuropathic pain. Instead, there is an upregulation of activity in the orbitofrontal and insular cortices, which is probably due to the stronger emotional load of neuropathic pain and higher computational demands of processing a mixed sensation of brush and pain.
-
Randomized Controlled Trial
The effects of noxious heat, auditory stimulation, a cognitive task, and time on task on pain perception and performance accuracy in healthy volunteers: a new experimental model.
The effects of cognitive and competing sensory processing tasks on pain perception and as a function of time are only partially understood. To study these effects, we compared the simultaneous effects of noxious heat stimulation (HS), auditory stimulation (AS) (sinusoidally modulated speech-like signal, SMSLS), and a cognitive task (CT) (rate change detection of the SMSLS) on pain perception and task performance over repeated experimental runs. Sixty healthy paid volunteers were randomly assigned to four groups, one exposed to AS while performing the CT, one to HS (46 degrees C/6 min), one to AS and HS, and one to AS and HS while performing the CT. ⋯ Neither pain rating, nor rate of errors on the CT varied significantly across runs. These findings point to a significant influence of competing passive sensory processing on pain perception, with the cognitive task not necessarily adding to the perception of pain. Advantages and shortcomings of the present experimental model for future pain studies are discussed.
-
Our aim was to asses the efficacy of deep brain stimulation in post-stroke neuropathic pain. Since 2000, 15 patients with post-stroke intractable neuropathic pain were treated with deep brain stimulation of the periventricular gray area (PVG), sensory thalamus (Ventroposterolateral nucleus-VPL) or both. ⋯ However, there is a wide variation between patients. This study demonstrates that it is an effective treatment in 70% of such patients.
-
Controlled Clinical Trial
Neural correlates of individual differences in pain-related fear and anxiety.
Although individual differences in fear and anxiety modulate the pain response and may even cause more suffering than the initiating physical stimulus, little is known about the neural systems mediating this relationship. The present study provided the first examination of the neural correlates of individual differences in the tendency to (1) feel anxious about the potentially negative implications of physical sensations, as measured by the anxiety sensitivity index (ASI), and (2) fear various types of physical pain, as indexed by the fear of pain questionnaire (FPQ). ⋯ These functional relationships cannot be wholly explained by generalized anxiety (indexed by STAI-T scores), which did not significantly correlate with activation of any regions. The present findings may help clarify both the impact of individual differences in emotion on the neural correlates of pain, and the roles in anxiety, fear, and pain processing played by medial and orbitofrontal systems.
-
Clinical Trial
Acute low back pain: pain-related fear and pain catastrophizing influence physical performance and perceived disability.
Pain-related fear and pain catastrophizing are associated with disability and actual performance in chronic pain patients. In acute low back pain (LBP), little is known about the prediction of actual performance or perceived disability by pain-related fear and pain catastrophizing. This experimental, cross-sectional study aimed at examining whether pain-related fear and pain catastrophizing were associated with actual performance and perceived disability. ⋯ Using the Roland Disability Questionnaire as a measure of perceived disability, both pain-related fear and pain catastrophizing, as measured with the Pain Catastrophizing Scale, were significantly predictive of perceived disability and more strongly than pain intensity was. The results of the current study suggest that pain-related fear is an important factor influencing daily activities in individuals suffering an episode of acute LBP. The study results have important clinical implications, especially in the development of preventive strategies for chronic LBP.