Topiramate versus Carbamazepine for the Treatment of Classical Trigeminal Neuralgia A Meta-Analysis

Background: Carbamazepine is currently the drug of first choice in the treatment of trigeminal neuralgia. However, it is reported as efficacious in only 70-80% of patients, and can be associated with adverse effects such as drowsiness, confusion, nausea, ataxia, nystagmus and hypersensitivity, which may necessitate discontinuation of medication. Therefore, alternative drugs such as oxcarbazepine, baclofen and topiramate are also used to treat the disease. Objectives: The aim of this study was to compare the effectiveness and safety of topiramate with carbamazepine in the treatment of classical trigeminal neuralgia. Methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) [Issue 3 of 12, March 2011], MEDLINE, EMBASE, the Chinese Biomedical Database (CBM), the Chinese National Knowledge Infrastructure (CNKI) and the Chinese Science and Technique Journals Database (VIP) for the period January 1998 to March 2011, and we also manually searched all relevant journals. We included all confirmed randomized controlled trials treating trigeminal neuralgia with topiramate and carbamazepine. We evaluated the risk of bias of the included trials according to the Cochrane Handbook for Systematic Reviews of Interventions, Version 5.1. The Cochrane Collaboration's software RevM an 5.1 was used for the meta-analysis. Results: A total of six randomized controlled trials with poor methodological quality were included. All trials were conducted in China. Altogether, they included 354 patients with trigeminal neuralgia. The results of the meta-analysis showed that topiramate was more effective than carbamazepine after a treatment duration of 2 months (relative risk [RR] = 1.20, 95% CI 1.04, 1.39, p = 0.01). However, no difference was found in the effectiveness rate after a treatment duration of 1 month (RR = 1.00, 95% CI 0.87, 1.14, p = 0.94), in the remission rate after a treatment duration of 1 month (RR = 1.06, 95% CI 0.83, 1.36, p = 0.63), in the remission rate after a treatment duration of 2 months (RR = 1.31, 95% CI 0.96, 1.80, p = 0.09) or in adverse events when comparing topiramate with carbamazepine. Conclusions: Present trials comparing topiramate with carbamazepine are all poor in methodological quality. A meta-analysis of these studies showed that the overall effectiveness and tolerability of topiramate did not seem to differ from carbamazepine in the treatment of classical trigeminal neuralgia. However, the meta-analysis yielded a favourable effect of topiramate compared with carbamazepine after a treatment duration of 2 months. Results were limited due to the poor methodological quality and the geographic localization of the randomized controlled trials identified. Therefore, large, international, well conducted, randomized controlled trials are needed to further assess the relative efficacy and tolerability of topiramate and carbamazepine in this indication.