Intranasal lidocaine for acute migraine: A meta-analysis of randomized controlled trials

Background
Intranasal lidocaine has been shown to be effective in treating patients with acute migraines; however, its efficacy is still controversial. In this study, we intend to assess the efficacy and safety of intranasal lidocaine compared with a placebo or an active comparator for the treatment of migraines.
Method
PubMed, EMBASE, Cochrane library, and Scopus databases were searched from their inceptions to November 2018. Randomized controlled studies investigating the efficacy of intranasal lidocaine compared with a placebo or an active comparator were selected. Two reviewers independently extracted and synthesized data using a random-effects model. The primary outcome was pain intensity. The secondary outcomes were success rate, the need for rescue medicine, and relapse occurrences. We registered the study at PROSPERO with an ID of CRD42018116226.
Results
Six studies (n = 613) were eligible for the meta-analysis. Overall, the results revealed that the study population who was administered intranasal lidocaine had a lower pain intensity at 5 min (standardized mean difference (SMD) = -0.61; 95% CI = -1.04 to -0.19) and 15 min (SMD = -0.72; 95% CI = -1.14 to -0.19), had a higher success rate (RR = 3.55; 95% CI: 1.89 to 6.64) and a less frequent need for rescue medicine (RR = 0.51; 95% CI = 0.36 to 0.72) than the control group. These beneficial effects were not observed when an antiemetic was administered. Furthermore, intranasal lidocaine use had no significant influence on the relapse rate (RR = 0.89; 95% CI = 0.51–1.56), regardless of the use of antiemetics. Using lidocaine caused local irritation in up to 49.4% of the patients in one report but did not cause major adverse events.
Conclusion
Intranasal lidocaine can be considered a useful option for patients with an acute migraine. It yields a high success rate, a low pain intensity, an infrequent need for rescue medicine, and tolerable adverse events. The administration of antiemetics is an important confounding factor.