Effects of IV morphine in central pain: a randomized placebo-controlled study.
OBJECTIVE
To investigate the effects of IV morphine on central pain syndromes through quantitative sensory testing and to assess the long-term benefit of oral morphine.


METHODS
After an initial open titration phase aiming to determine the maximal tolerated dosage of IV morphine, the efficacy of morphine infusion (9-30 mg; mean dosage, 16 mg) was assessed in a double-blind, placebo-controlled and crossover fashion in 15 patients with poststroke- (6 patients) or spinal cord injury- (9 patients) related pain. All of the patients subsequently received sustained oral morphine.


RESULTS
Morphine significantly reduced the intensity of brush-induced allodynia but had no effect on other evoked pains (i.e., static mechanical and thermal allodynia/hyperalgesia). The effects of morphine on ongoing pain were not significantly different from those of the placebo, but 7 patients (46%) responded to morphine. There was a correlation between the effects of morphine on spontaneous pain and the decrease of the responses to suprathreshold thermal stimuli on the nonpainful contralateral side, suggesting that these effects were related to the general antinociceptive activity of the drug. The effects of IV morphine were correlated with those of oral morphine at 1 month, but only 3 patients (20%) were still taking morphine after 1 year.


CONCLUSIONS
IV morphine induces analgesic effects on some components of central neuropathic pain syndromes, but only a minority of patients may benefit from long-term opioid treatment.
Attal
N
N
Centre d'Evaluation et de Traitement de la Douleur et Département d'Anesthésiologie, Hôpital Ambroise Paré, Boulogne, France.
Guirimand
F
F
Brasseur
L
L
Gaude
V
V
Chauvin
M
M
Bouhassira
D
D
D000328:Adult; D000368:Aged; D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000009:adverse effects; D000704:Analysis of Variance; D002908:Chronic Disease; D003080:Cold Temperature; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006358:Hot Temperature; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D009020:Morphine / Q000008:administration & dosage* / Q000009:adverse effects; D010146:Pain / Q000188:drug therapy* / Q000209:etiology / Q000523:psychology; D017288:Pain Threshold / Q000187:drug effects; D018709:Statistics, Nonparametric
D000701:Analgesics, Opioid; D009020:Morphine