Pain
-
Randomized Controlled Trial
Treating pain with pain: supraspinal mechanisms of endogenous analgesia elicited by heterotopic noxious conditioning stimulation.
While being exposed to an intensive tonic pain stimulus at one area of the body, another phasic pain stimulus applied to a remote site is perceived as less painful. The neurophysiological basis for this "pain inhibits pain" phenomenon has been presumed to be an activation of the spino-bulbo-spinal mechanism termed "diffuse noxious inhibitory controls." However, several additional mechanisms such as an activation of the descending pain control system may contribute to this observation. Here we investigated the underlying supraspinal mechanisms of "heterotopic noxious conditioning stimulations" (HNCS), representing this specific experimental constellation. ⋯ These effects were in part reversed by naloxone, speaking for the contribution of endogenous opioid neurotransmission to this mechanism. Taken together, these results demonstrate a substantial contribution of higher-order brain regions to the phenomenon of hypoalgesia during HNCS. Functional magnetic resonance imaging shows how the human brain is involved in heterotopic noxious conditioning and reveals active supraspinal pain modulatory mechanisms during dual pain stimulation.
-
Randomized Controlled Trial
Duloxetine in patients with central neuropathic pain caused by spinal cord injury or stroke: a randomized, double-blind, placebo-controlled trial.
The mechanisms underlying central neuropathic pain are poorly understood. Pain inhibitory mechanisms including sertononergic and norepinephrine systems may be dysfunctional. In this randomized, double-blinded, placebo-controlled trial we evaluated the effects of duloxetine on pain relief (spontaneous pain and evoked pain), tolerability, health status, and quality of life in patients with central pain related to cerebrovascular lesions or spinal cord lesions. ⋯ No significant differences were observed in the other domains of the SF36, the Pain Disability Index, and the EQ-5D. While this trial showed no significant effect on pain intensity, duloxetine revealed a biologic effect. It would be worthwhile to suspend our judgement and to perform more studies to evaluate the role of duloxetine in modulation of the symptoms of central neuropathic pain.
-
Comparative Study
TNF-α in CRPS and 'normal' trauma--significant differences between tissue and serum.
Posttraumatic TNF-alpha signaling may be one of the factors responsible for pain and hyperalgesia in complex regional pain syndromes (CRPS). In order to further specify the role of TNF-alpha we investigated tissue (skin) and serum concentrations in three different patient groups: patients with osteoarthritis and planned surgery, with acute traumatic upper limb bone fracture waiting for surgery, and with CRPS I. Thirty patients (10 in each group) were recruited. ⋯ In contrast, serum TNF-alpha values were the same in osteoarthritis and CRPS, and lower in fracture patients (p<0.03). Our results indicate a local but not systemic increase of TNF-alpha in CRPS patients. This increase persists for months after limb trauma and may offer the opportunity for targeted treatment.