European journal of pain : EJP
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Randomized Controlled Trial Multicenter Study Comparative Study
Sustained-release oral morphine versus transdermal fentanyl and oral methadone in cancer pain management.
The aim of this study was to compare the analgesic and adverse effects, doses, as well as cost of opioid drugs, supportive drug therapy and other analgesic drugs in patients treated with oral sustained-release morphine, transdermal fentanyl, and oral methadone. ⋯ All the three opioids used as first-line therapy were effective, well tolerated, and required similar amounts of symptomatic drugs or co-analgesics. Methadone was significantly less expensive, but required more changes, up and down, of the doses, suggesting that dose titration of this drug requires major clinical expertise.
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The middle cingulate cortex (MCC) has been implicated in pain processing by studies of cingulotomy for chronic pain and imaging studies documenting increased MCC blood flow in response to acute pain. The only previous report of quantitative sensory testing following cingulotomy described increased intensity and unpleasantness ratings of painful hot and cold stimuli in a single patient with psychiatric disease. We now report a case in which perception of pain and temperature was assessed before and after cingulotomy for obsessive-compulsive disorder (OCD). ⋯ Postoperative pain-evoked activation was demonstrated in the right (ipsilateral) parasylvian cortex but not of the MCC/SMA. Prior studies of forebrain lesions, and of cortical synchrony during the application of painful stimuli suggest the presence of functional connectivity between components of the MCC/SMA and the fronto-parietal opercula. Therefore present results suggest that cingulate lesions disinhibit ipsilateral parasylvian cortex and so are independent evidence of functional connectivity between these cortical areas, the defining characteristic of modules in a pain network.
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An appropriate bedside test for small fiber neuropathy does not exist so far. Cold hypaesthesia occurs as an early onset symptom, and the new handheld device NeuroQuick (NQ) was recently claimed to be a valid and reliable screening tool for its quantitative assessment. ⋯ This study demonstrates that the NeuroQuick is not an adequate screening device for cold hypaesthesia in patients with chronic neuropathic pain. It exhibits a high specificity but only low sensitivity in the identification of such small fiber dysfunction; a reliable and valid screening tool should necessarily provide opposite features.
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Carriers of a particular haplotype of the GTP cyclohydrolase gene (GCH1) had less pain after surgery for chronic lumbar radiculopathy and a decreased sensitivity to some experimental mechanical pain stimuli. Ex-vivo, GCH1 upregulation and BH4 production after forskolin stimulation were reduced, while baseline BH4 concentrations were not affected. This suggested that the haplotype may mainly exert its modulating function when the GCH1 system is provoked. The present study aimed at (i) testing this hypothesis and (ii) independently reproducing the pain-decreasing effects of a particular GCH1 haplotype having been previously associated with pain protection. ⋯ This study verifies previous results that decreased GCH1 function or inducibility as a result of genetic polymorphisms protects against pain. This study extents previous results by showing that this pain protection is mainly conferred under conditions of hyperalgesia resulting from sensitization, supporting specific functions of BH4 in relation to particular aspects of pain.
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Antidepressant drugs act mainly by blocking the noradrenaline and/or serotonin uptake sites and require a chronic treatment. Tricyclic antidepressants are among the first line treatments clinically recommended against neuropathic pain. As observed against depression, a chronic treatment is required for a therapeutic effect. ⋯ For comparison, we tested the anticonvulsant gabapentin and showed that it alleviates neuropathic allodynia after 3 days of treatment. Naloxone had no effect on gabapentin therapeutic benefit, showing that antidepressants and anticonvulsants alleviate neuropathic allodynia through independent mechanisms. Our work provides a clinically relevant model to understand the mechanism by which chronic antidepressant treatment can alleviate neuropathic pain.