Analysis of peak magnitude and duration of analgesia produced by local anesthetics injected into sympathetic ganglia of complex regional pain syndrome patients.
OBJECTIVE
Pain-relieving effects of lidocaine/bupivicaine local anesthetic (LA) and saline (S) block of sympathetic ganglia (stellate block, 4 patients; lumbar sympathetic block, 3 patients) were compared in 7 complex regional pain syndrome (CRPS) patients on a double-blind crossover basis to evaluate the diagnostic and therapeutic value of local anesthetic sympathetic blocks.


METHODS
Patients rated their pain on a visual analog scale before and after blocks and were tested for mechanical allodynia one-half hour after blocks. Thereafter, they rated their pain intensity in diaries four times a day for 7 days. Each patient received two blocks, S and LA, and served as his own control.


RESULTS
Both S and LA injections of sympathetic ganglia produced large reductions in pain intensity in 6 of 7 patients 30 minutes after block. These large reductions were accompanied by the reversal of mechanical allodynia in both S and LA. The mean difference between initial peak reduction in pain intensity produced by saline (68.7%) and active local anesthetic (74.4%) did not approach statistical significance. In striking contrast, the mean duration of pain relief was reliably longer in the case of LA (3 days, 18 hours) as compared with S ( 19.9 hours), a difference that occurred in all 7 patients. In a larger sample of 41 CRPS patients, signs of sympathetic efferent blockade, including Homer' s syndrome or skin surface temperature change, were not predictive of initial peak magnitude of pain relief from sympathetic blockade but were predictive of duration of pain reduction.


CONCLUSIONS
The combination of these results provides evidence that duration of pain relief is affected by injection of local anesthetics into sympathetic ganglia. These results indicate that both magnitude and duration of pain reduction should be closely monitored to provide optimal efficacy in procedures that use local anesthetics to treat CRPS.
Department of Oral and Maxillofacial Surgery, University of Florida, Gainesville 32610, USA.
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Price
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Long
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Wilsey
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Rafii
D000328:Adult; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000627:therapeutic use*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D005728:Ganglia, Sympathetic / Q000502:physiology*; D005730:Ganglionic Blockers / Q000008:administration & dosage / Q000627:therapeutic use; D006801:Humans; D007267:Injections; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement / Q000187:drug effects; D012019:Reflex Sympathetic Dystrophy / Q000188:drug therapy*; D013233:Stellate Ganglion / Q000502:physiology; D013577:Syndrome; D013997:Time Factors
D000779:Anesthetics, Local; D005730:Ganglionic Blockers