Botulinum toxin type A versus pregabalin in the treatment of refractory trigeminal neuralgia: a multicenter, triple blind, double dummy, randomized controled clinical trial

Bermejo Soler, Isabel
Background: Trigeminal neuralgia is a chronic disease characterised by recurrent attacks of brief episodes of intense electric shock-line pain in the distribution of one or more divisions of the trigeminal nerve. In most cases, these attacks are unleashed by stimulus like talking, brushing teeth or shaving. The pain is usually unilateral and lasts from few seconds to two minutes but patients may have until 50 attacks per day strongly affecting their quality of life. The only drug with strong evidence and with grade of recommendation A is Carbamazepine. However, in some patients this treatment is not useful or has high rate of adverse events. Second line options could be Oxcarbazepine, Lamotrigine or Baclofen. There is no evidence about which treatment should patients receive once these options have failed. Selected patients could undergo different surgical procedures but they are not exempt from risks and adverse effects. Recently, some randomized controlled trials compared the efficacy of Botulinum Toxin type A (BTX-A) versus placebo in refractory patients with good results. Pregabalin has also shown to be an effective option in some studies. However, there are no studies comparing both drugs. Objectives: The main purpose of this study is to compare the efficacy of BTX-A versus Pregabalin in the treatment of patients diagnosed with trigeminal neuralgia that do not respond to, at least, two different pharmacologic treatments. Design: Multicentric, triple blind, double dummy, randomized controlled clinical trial. Methods: Patients enrolled in this study will be randomized in two groups (A and B). The group A (n=50) will receive injections of BTX-A in the affected area and will be provided with placebo pills while the group B (n=50) will receive injections of sterile isotonic saline (placebo) and Pregabalin pills in order to treat their refractory trigeminal neuralgia. Injections will be performed twice during the study, at the beginning and twelve weeks later. The other medication will be taken twice a day during the six month of the trial. We define treatment efficacy when there is a reduction >50% in the mean of the Visual Analogue Scale (VAS) score from baseline to endpoint. The frequency of the attacks, an overall response to treatment and safety of these drugs will be evaluated and recorded. Patients will be followed-up every week during the first month and every two weeks during the next five months. Participants: Adults diagnosed of trigeminal neuralgia with insufficient therapy response with at least 2 treatment attempts (one of them has to be Carbamazepine) or intolerable side effects ​
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