Lack of Effect of Sphenopalatine Ganglion Block With Intranasal Lidocaine on Submaximal Effort Tourniquet Test Pain

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Abstract

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 (SPGBlidocaline) or placebo (SPGBsaline). 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 SPGBsaline, and 11.1 ± 2.5 after SPGBlidocaine. No significant differences were noted between SPGBlidocaineand SPGBsalineat any of the 15 time points (p= NS by repeated measures ANOVA and pairedt-test). However, retrospective grouping of time points noted that scores after SPGBlidocainewere 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.

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