| Background: Non-antiepileptic drugs have been used in trigeminal neuralgia management since the 1970s. Drugs used include baclofen, pimozide, tizanidine, proparacaine and tocainide. A number of randomized controlled trials of non-antiepileptic drugs for treating trigeminal neuralgia have been published in recent years, but their results were not consistent. There is no known systematic review of non-antiepileptic drugs treatment for trigeminal neuralgia.Objectives:The objective of this review was to examine the efficacy of non-antiepileptic drugs to treat trigeminal neuralgia.Search strategy: According to the collaborative review group search strategy, we searched the Cochrane Neuromuscular Disease Group register for randomized controlled trials published in all languages. We also searched MEDLINE, EMBASE, LILACS, the Chinese Biomedical Retrieval System, the RCT, CCT Database of Chinese EBM/Cochrane Center and conference paper databases. We searched ten journals (including the Chinese Journal of Neurology) by hand.Selection criteria: We searched for all randomized or quasi-randomized controlled trials involving non-antiepileptic drugs in the treatment of trigeminal neuralgia irrespective of any language restrictions. The primary outcome measure was the proportion of patients with a good initial effect evaluated by pain intensity or trigeminal neuralgia score one to eight weeks after treatment, The secondary outcome measures were the number of patients with a good long-term effect evaluated by pain intensity or trigeminal neuralgia score at least twelve weeks after treatment and thenumber of patients reporting adverse effects attributable to non-antiepileptic drugs.Data collection & analysis: Two reviewers decided which trials fit the inclusion criteria and graded their methodological quality independently. Information about included trials was collected from each study. We calculated weighted treatment effect with Review Manager 4.2. Results were expressed as RRs with 95% confidence intervals for dichotomous outcomes and WMD with 95% confidence intervals for continuous outcomes. Main results: We identified 13 reports which might meet the inclusion criteria for our review. Nine trials were eligible for our study. Three studies were excluded. One trial is awaiting further evaluation. Eight trials reported the proportion of patients with a good initial effect one to eight weeks after treatment. Only one trial observed the number of patients with a good long-term effect at 3 months after treatment. Four trials recorded adverse effects of non-antiepileptic drugs, but only two trials compared the adverse effects of the non-antiepileptic drug with that of the control drug. Because the non-antiepileptic drugs tested in the included studies were different, we did not combine the results. And because different control drugs were used in the studies investigating the same non-antiepileptic drugs, we did not undertake subgroup analysis. Instead we calculated the effect size and described the characteristics of each individual trial. We found that baclofen significantly relieved trigeminal neuralgia when compared to placebo. When baclofen was compared with carbamazepine, there was only a tendency to increase the proportion of people with relief of pain compared to those treated with carbamazepine. Although there was no significant difference in the numberof patients with pain relief when treated with L-Baclofen compared with racemic baclofen, L-Baclofen produced a significant decrease in the number of attacks of trigeminal neuralgia. The decrease in the number of attacks was five times that of racemic baclofen. The adverse effects with L-Baclofen were also less than those with racemic baclofen. Tizanidine increased the number of people who improved in pain significantly compared with placebo, but only few people obtained pain free status and the long-term effect was also not good. When compared with carbamazepine, the tendency indicated that the effect of tizanidine was worse than that of carbamazepine. Proparacaine hydrochloride 0.5% instillation into the eyes was simple and safe, but no significant effect was apparent when compared with placebo. Tocainide had a similar effect as carbamazepine, but the serious side effects that maybe life-threatening restricted the clinical use of the drug. Pimozide, a neuroleptic drug, was better in controlling pain especially intractable TN than carbamazepine in one double-blind crossover RCT, but adverse effects were common. Only one trial reported the long-term effect of non-antiepileptic drugs. This trial indicated that clomipramine was more effective than amitriptyline in tendency. No randomized controlled trial was found comparing clomipramine with carbamazepine.Reviewers' conclusions: This review indicates that although there are trials of non-antiepileptic drugs for trigeminal neuralgia, they are limited by poor methodological quality. No sufficient evidence certifies the efficacy and safety of the non-antiepileptic drugs at present. We have no evidence to recommend these non-antiepileptic drugs as routine therapeutics for trigeminal neuralgia. But some non-antiepileptic drugs such as baclofen,pimozide, tocainide, chlorimipramine have potential. It is necessary to carry out high quality and large sample size RCTs to further ascertain the effect of these drugs. Future trials should improve their design. Measurement tools such as VAS, NRS, VRS, which have good reliability and validity, should be used to assess pain. |
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