Pain
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Randomized Controlled Trial Clinical Trial
Activation of the cortical pain network by soft tactile stimulation after injection of sumatriptan.
The anti-migraine drug sumatriptan often induces unpleasant somatosensory side effects, including a dislike of being touched. With a double-blind cross-over design, we studied the effects of sumatriptan and saline on perception (visual analogue scale) and cortical processing (functional magnetic resonance imaging) of tactile stimulation in healthy subjects. Soft brush stroking on the calf (n=6) was less pleasant (p<0.04) and evoked less activation of posterior insular cortex in the sumatriptan compared to the saline condition. ⋯ Another possibility is inhibition of a recently discovered system of low-threshold unmyelinated tactile (CT) afferents that are present in hairy skin only, project to posterior insular cortex, and serve affective aspects of tactile sensation. An inhibition of impulse transmission in the CT system by sumatriptan could disinhibit nociceptive signalling and make light touch less pleasant. This latter alternative is consistent with the observed reduction in posterior insular cortex activation and the selective effects of stimulation on hairy compared to glabrous skin, which are not explained by the nociceptor sensitization account.
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Randomized Controlled Trial Multicenter Study Clinical Trial
Sativex successfully treats neuropathic pain characterised by allodynia: a randomised, double-blind, placebo-controlled clinical trial.
Cannabinoids are known to have analgesic properties. We evaluated the effect of oro-mucosal sativex, (THC: CBD), an endocannabinoid system modulator, on pain and allodynia, in 125 patients with neuropathic pain of peripheral origin in a five-week, randomised, double-blind, placebo-controlled, parallel design trial. Patients remained on their existing stable analgesia. ⋯ Sedative and gastrointestinal side effects were reported more commonly by patients on active medication. Of all participants, 18% on sativex and 3% on placebo withdrew during the study. An open-label extension study showed that the initial pain relief was maintained without dose escalation or toxicity for 52 weeks.