Two Doses Of Botulinum Toxin Type A For The Treatment Of Trigeminal Neuralgia:Observation Of Therapeutic Effect From A Randomized, Double-blind,Placebo-controlled Trial

Objective:In the majority of cases, trigeminal neuralgia (TN) is a unilateral condition with ultra-short stabbing pain located along one or more branches of the trigeminal nerve. The treatment consists primarily of prophylactic pharmacological treatment. In case of insufficient effect or unacceptable side effects, neurosurgical treatment or lesion treatment should be considered. In addition to all these procedures mentioned above, one approach has been based on local intradermal and/or submucosal injections of Botulinum Toxin Type A (BTX-A). BTX-A is one of the serotypes of botulinum neurotoxins derived from Clostridium botulinum and it is reported to be effective in controlling the pain of some diseases. The results of some open-label trials and a randomized, double-blind, placebo-controlled trial have suggested that BTX-A may be effective in the management of trigeminal neuralgia. But there is no dose-ranging studies to date. We conducted a randomized, double-blind, placebo-controlled trial to clarify therapeutic effect of two doses of BTX-A in patients with classical trigeminal neuralgia. Methods:We conducted a randomized, double-blind, placebo-controlled trial since November2011, and adopted local multi-point injection in84cases of classical TN with different doses of BTX-A. Eighty four patientswere randomized into following groups:placebo (n=28); BTX-A25U (n=27); BTX-A75U (n=29). Follow-up visits were conducted every week after the injection, and the overall duration of the study for each patient were8weeks to observe the pain severity, efficacy and adverse reactions at endpoint.Results:The visual analogue scale (VAS) scores of25U and75U groups reduced significantly compared to placebo as early as week1, and sustained until week8throughout the study. There was no significant difference in VAS between25U and75U groups throughout the study. The response rates of25U group (70.4%) and75U group (86.2%) were significantly higher than placebo group (32.1%) at week8, and there was no significant difference between25U and75U groups. Evaluation of the Patient Global Impression of Change (PGIC) demonstrated that66.7%(25U group) and75.9%(75U group) of the patients reported that their pain symptoms were ’much improved’ or ’very much improved’ versus32.1%of the placebo group, and there was also no significant difference between25U and75U groups. All adverse reactions were graded as mild or moderate.Conclusions:BTX-A injection in TN is safe and efficient. It is a useful tool for refractory TN. Lower dose (25U) and high dose (75U) were similar in efficacy in short-term.