European journal of pain : EJP
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After intramuscular (m. tibialis anterior) injection of three different algogenic substances, the pain intensity was continuously scored on a visual analogue scale (VAS) in eight volunteers. The subject drew the distribution of the local and referred pain areas on a map. Four times within the first hour after injection, the pressure pain-thresholds (PPTs) and supra pressure-pain thresholds were assessed at the injection point, 2 cm distal from the injection site, at the arm, and at the contralateral leg. ⋯ We conclude that under the present experimental conditions, BKN and 5-HT can produce low levels of muscle pain after intramuscular injection. In the used concentrations, however, BKN, 5-HT, and SP did not generate cutaneous or muscular hyperalgesia. Copyright 1999 European Federation of Chapters of the International Association for the Study of Pain.
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The aim of this investigation was to study the effect of suggestions of hypnotic analgesia on spinal pain transmission and processing. Pain intensity and amplitude of nociceptive withdrawal reflexes to electrical stimuli were measured in 10 high- and 10 low-hypnotizable subjects during two sessions taking place at least 24 h apart under five conditions of: (1) pre-hypnosis; (2) neutral hypnotic relaxation; (3) suggestions of hypnotic analgesia; (4) suggestions of hypnotic analgesia after injections of either naloxone (1 ml, 1 mg/ml) or saline (1 ml) under double-blinded conditions; and (5) post-hypnosis. The conditions of naloxone or saline were allocated at random to either Day 1 or Day 2 in a double-blinded fashion. ⋯ These results suggest that the effect of naloxone was related to the greater stimulus intensities needed to elicit a reflex in the high-hypnotizable group, rather than to hypnosis or hypnotic susceptibility in itself. It is unclear why greater stimulus intensities were needed in high-hypnotizable subjects and further studies are needed. Copyright 1998 European Federation of Chapters of the International Association for the Study of Pain.
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Peripheral nerve injury may lead to neuropathic pain that has been considered unresponsive to opioids. In animal models of neuropathic pain, there are previous data of both increased and decreased effect of opioids, but only limited information of the long-term effects of opioid treatment on the development of the symptoms of neuropathy. The possibility of preventing the development of signs of neuropathy with either a single pre-injury injection or chronic postinjury administration of morphine was studied in rats with unilateral peripheral neuropathy due to tight ligation of the L5 and L6 spinal nerves. ⋯ No autotomy, signs of distress, altered social behaviour or morphine withdrawal was seen in any of the rats. The fact that neuropathic pain-like symptoms were not attenuated by any of the treatments studied could indicate that neither premedication nor postoperative pain management with systemic morphine is effective in preventing postoperative neuropathic pain. Copyright 1998 European Federation of Chapters of the International Association for the Study of Pain.
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There is no reliable method to relieve both 'refractory' pain and spasticity in patients with multiple sclerosis (MS). This paper reports on the long-term use of continuous intrathecal bupivacaine infusion in such a patient. The patient under study was a 56-year-old woman affected for 18 years by MS, unsuccessfully treated with analgesics, baclofen, opioids, peripheral neurolysis (obturator nerves, lumbar plexus) and six intrathecal neurolyses of the L4-S3 nerve roots, each time with 1.5 ml of 50% phenol in glycerol. ⋯ The treatment was given for 712 days, at which point the patient died (unrelated to the treatment). Intrathecal infusion of bupivacaine relieved 'refractory' spasticity and pain in a MS patient in whom administration of intrathecal baclofen was contraindicated and neurodestructive procedures had been inefficient. Copyright 1998 European Federation of Chapters of the International Association for the Study of Pain.
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Projections from the locus coeruleus (LC) to the centrolateral thalamus (Cl) and the medial prefrontal cortex (PfCx) were studied using orthodromic and antidromic stimulation techniques. The LC is a major noradrenergic source in the central nervous system, and its descending projections provide an important source of pain suppression at spinal level. Previously, the author has described a cortico-thalamic loop involved in pain modulation. ⋯ The paper also describes the suppression of spontaneous and nociceptive-evoked activity in the PfCx and Cl following electrical stimulation in LC. It is proposed that the LC innervation could be associated with an ascending noradrenergic system acting upon a Cl-PfCx pain-modulation mechanism. Copyright 1998 European Federation of Chapters of the International Association for the Study of Pain.