Background and Objectives. The present study examined whether sphenopalatine ganglion block (SPGB) causes a reduction in the response to acute nociceptive input that may account for the SPGB-induced relief reported by many patients with chronic pain.
Methods. In a double-blind, cross-over design, 16 healthy volunteers underwent separate 15-minute submaximal effort tourniquet tests before and after SPGB with 20% lidocaine plus 1:100,000 epinephrine (SPGB lidocaline ) or placebo (SPGB saline ). Responses during each minute of tourniquet inflation were converted to a 1 to 16 scale and classified as nothing (1), mild sensation (2-4), strong sensation (5-7), slightly painful (8-10), definitely painful (11-13), and severely painful (14-16).
Results. Maximum pain scores reached 12.6 ± 2.5 (mean ± SD) pre-SPGB, 10.9 ± 3.5 after SPGB saline , and 11.1 ± 2.5 after SPGB lidocaine . No significant differences were noted between SPGB lidocaine and SPGB saline at any of the 15 time points ( p = NS by repeated measures ANOVA and paired t -test). However, retrospective grouping of time points noted that scores after SPGB lidocaine were lower in the “strong sensation” range.
Conclusion. SPGB does not lessen acute extremity pain to a significant degree and is not in and of itself an effective means of analgesia for acute pain. Its potential impact on nociceptive stimuli that elicit a “strong sensation” (i.e., a score of 5-7 in the present study) should be evaluated in hyperpathic pain states and in states with exaggerated aversive responses.
- nerve block
- sphenopalatine ganglion
- tourniquet test
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Supported by Yale University School of Medicine Office of Student Research and National Institutes of Health Grant NS09871. Performed at The Yale General Clinical Research Center, supported by The Division of Research Resources Grant RR-125.
The authors thank Drs. Milton Reder and Edmund Goodman for their hands-on instruction in the performance of sphenopalatine ganglion block; the nursing staff of the Clinical Research Center at Yale University Medical Center; and Miss Jacki Fitzpatrick for assistance in manuscript preparation.