Evaluation of Botulinum Toxin Injection Efficacy in the Treatment of Head Essential Tremor by a Multi-center, Randomized, Double-Blind, Parallel-group, Placebo-controlled Study

Essential head tremor (HT) does not usually respond to drug treatment such as propranolol or primidone or to surgical treatment such as deep brain stimulation of the thalamic ventralis intermedius nucleus. Botulinum toxin (Btx) is widely used and efficient in the treatment of blepharospasm and cervical dystonia. Btx prevents the release of acetylcholine in synapses, leading to a reduction of pathological muscle movement. Very little information is available on its efficacy on HT. Two published reports suggested that local Btx A injections could be an effective and safe approach for treating HT. Given the scarcity of published data (small samples, open studies, different doses of Btx used, heterogeneous populations, several muscles injected, etc.), the aim of this study is to demonstrate the efficacy of Btx injections in essential HT by a multi-center, randomized, double-blind, parallel-group, placebo-controlled study. Principal objective: To evaluate the efficacy of botulinum toxin injections in the treatment of head tremor. Secondary objectives: - To evaluate the tolerance of botulinum toxin injections in the treatment of head tremor. - To evaluate the impact of botulinum toxin injections on the patients' quality of life and embarrassment. To evaluate the changes of tremor characteristics induced by a Btx treatment using a 3D accelerometer wireless portable system (Xsens MTw wireless motion tracker system) (tremor frequency, tremor displacement, mean peak amplitude, distance traveled) and a new video system device to analyze head tremor characteristics